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? 2004 microchip technology inc. ds39609b pic18f6520/8520/6620/8620/6720/8720 data sheet 64/80-pin high-performance, 256 kbit to 1 mbit enhanced flash microcontrollers with a/d
ds39609b-page ii ? 2004 microchip technology inc. information contained in this publication regarding device applications and the like is intended through suggestion only and may be superseded by updates. it is your responsibility to ensure that your application m eets with your specifications. no representation or warranty is given and no liability is assumed by microchip technol ogy incorporated with respect to the accuracy or use of such information, or infringement of patents or other intellectual property rights arising from such use or otherwise. use of mi crochip?s products as critical components in life support syst ems is not authorized except with express written approval by microchip. no licenses are conveyed, implicitly or ot herwise, under any intellectual property rights. trademarks the microchip name and logo, the microchip logo, accuron, dspic, k ee l oq , mplab, pic, picmicro, picstart, pro mate and powersmart are registered trademarks of microchip technology incorporated in the u.s.a. and other countries. amplab, filterlab, micro id , mxdev, mxlab, picmaster, seeval, smartshunt and the embedded control solutions company are registered trademarks of microchip technology incorporated in the u.s.a. application maestro, dspicdem, dspicdem.net, dspicworks, ecan, economonitor, fansense, flexrom, fuzzylab, in-circuit serial programming, icsp, icepic, microport, migratable memory, mpasm, mplib, mplink, mpsim, pickit, picdem, picdem.net, pictail, powercal, powerinfo, powermate, powertool, rflab, rfpic, select mode, smartsensor, smarttel and total endurance are trademarks of microchip technology incorporated in the u.s.a. and other countries. serialized quick turn programming (sqtp) is a service mark of microchip technology incorporated in the u.s.a. all other trademarks mentioned herein are property of their respective companies. ? 2004, microchip technology incorporated, printed in the u.s.a., all rights reserved. printed on recycled paper. note the following details of the code protection feature on microchip devices: microchip products meet the specification cont ained in their particular microchip data sheet. microchip believes that its family of products is one of the mo st secure families of its kind on the market today, when used i n the intended manner and under normal conditions. there are dishonest and possibly illegal methods used to breach the code protection feature. all of these methods, to our knowledge, require using the microchip produc ts in a manner outside the operating specif ications contained in microchip's data sheets. most likely, the person doing so is engaged in theft of intellectual property. microchip is willing to work with the customer who is concerned about the integrity of their code. neither microchip nor any other semicondu ctor manufacturer can guarantee the security of their code. code protection does not mean that we are guaranteeing the product as ?unbreakable.? code protection is constantly evolving. we at microchip are comm itted to continuously improving t he code protection features of our products. attempts to break microchip?s c ode protection feature may be a violation of the digital millennium copyright act. if such acts allow unauthorized access to your software or other copyrighted work, you may have a right to sue for relief under that act. microchip received iso/ts-16949:2002 quality system certification for its worldwide headquarters, design and wafer fabrication facilities in chandler and tempe, arizona and mountain view, california in october 2003. the company?s quality system processes and procedures are for its picmicro ? 8-bit mcus, k ee l oq ? code hopping devices, serial eeproms, microperipherals, nonvolatile memory and analog products. in addition, microchip?s quality system for the design and manufacture of development systems is iso 9001:2000 certified.
? 2004 microchip technology inc. ds39609b-page 1 pic18f6520/8520/6620/ 8620/6720/8720 high-performance risc cpu: c compiler optimized architecture/instruction set: - source code compatible with the pic16 and pic17 instruction sets linear program memory addressing to 128 kbytes linear data memory addressing to 3840 bytes 1 kbyte of data eeprom up to 10 mips operation: - dc ? 40 mhz osc./clock input - 4 mhz ? 10 mhz osc./clock input with pll active 16-bit wide instructions, 8-bit wide data path priority levels for interrupts 31-level, software accessible hardware stack 8 x 8 single cycle hardware multiplier external memory interface (pic18f8x20 devices only): address capability of up to 2 mbytes 16-bit interface peripheral features: high current sink/source 25 ma/25 ma four external interrupt pins timer0 module: 8-bit/16-bit timer/counter timer1 module: 16-bit timer/counter timer2 module: 8-bit timer/counter timer3 module: 16-bit timer/counter timer4 module: 8-bit timer/counter secondary oscillator clock option ? timer1/timer3 five capture/compare/pwm (ccp) modules: - capture is 16-bit, max. resolution 6.25 ns (t cy /16) - compare is 16-bit, max. resolution 100 ns (t cy ) - pwm output: pwm resolution is 1 to 10-bit master synchronous serial port (mssp) module with two modes of operation: - 3-wire spi? (supports all 4 spi modes) -i 2 c? master and slave mode two addressable usart modules: - supports rs-485 and rs-232 parallel slave port (psp) module analog features: 10-bit, up to 16-channel analog-to-digital converter (a/d): - conversion available during sleep programmable 16-level low-voltage detection (lvd) module: - supports interrupt on low-voltage detection programmable brown-out reset (pbor) dual analog comparators: - programmable input/output configuration special microcontroller features: 100,000 erase/write cycle enhanced flash program memory typical 1,000,000 erase/write cycle data eeprom memory typical 1 second programming time flash/data eeprom retention: > 40 years self-reprogrammable under software control power-on reset (por), power-up timer (pwrt) and oscillator start-up timer (ost) watchdog timer (wdt) with its own on-chip rc oscillator for reliable operation programmable code protection power saving sleep mode selectable oscillator options including: - 4x phase lock loop (of primary oscillator) - secondary oscillator (32 khz) clock input in-circuit serial programming? (icsp?) via two pins mplab ? in-circuit debug (icd) via two pins cmos technology: low-power, high-speed flash technology fully static design wide operating voltage range (2.0v to 5.5v) industrial and extended temperature ranges device program memory data memory i/o 10-bit a/d (ch) ccp (pwm) mssp usart timers 8-bit/16-bit ext bus max f osc (mhz) bytes # single-word instructions sram (bytes) eeprom (bytes) spi master i 2 c pic18f6520 32k 16384 2048 1024 52 12 5 y y 2 2/3 n 40 pic18f6620 64k 32768 3840 1024 52 12 5 y y 2 2/3 n 25 pic18f6720 128k 65536 3840 1024 52 12 5 y y 2 2/3 n 25 pic18f8520 32k 16384 2048 1024 68 16 5 y y 2 2/3 y 40 pic18f8620 64k 32768 3840 1024 68 16 5 y y 2 2/3 y 25 pic18f8720 128k 65536 3840 1024 68 16 5 y y 2 2/3 y 25 64/80-pin high-performance, 256 kbit to 1 mbit enhanced flash microcontrollers with a/d
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 2 ? 2004 microchip technology inc. pin diagrams pic18f6620 1 2 3 4 5 6 7 8 9 10 11 12 13 14 38 37 36 35 34 33 50 49 17 18 19 20 21 22 23 24 25 26 re2/cs re3 re4 re5 re6 re7/ccp2 (1) rd0/psp0 v dd v ss rd1/psp1 rd2/psp2 rd3/psp3 rd4/psp4 rd5/psp5 rd6/psp6 rd7/psp7 re1/wr re0/rd rg0/ccp3 rg1/tx2/ck2 rg2/rx2/dt2 rg3/ccp4 mclr /v pp rg4/ccp5 v ss v dd rf7/ss rf6/an11 rf4/an9 rf3/an8 rf2/an7/c1out rb0/int0 rb1/int1 rb2/int2 rb3/int3 rb4/kbi0 rb5/kbi1/pgm rb6/kbi2/pgc v ss osc2/clko/ra6 osc1/clki v dd rb7/kbi3/pgd rc4/sdi/sda rc3/sck/scl rc2/ccp1 rf0/an5 rf1/an6/c2out av dd av ss ra3/an3/v ref + ra2/an2/v ref - ra1/an1 ra0/an0 v ss v dd ra4/t0cki ra5/an4/lvdin rc1/t1osi/ccp2 (1) rc0/t1oso/t13cki rc7/rx1/dt1 rc6/tx1/ck1 rc5/sdo 15 16 31 40 39 27 28 29 30 32 48 47 46 45 44 43 42 41 54 53 52 51 58 57 56 55 60 59 64 63 62 61 pic18f6720 rf5/an10/cv ref 64-pin tqfp pic18f6520 note 1: ccp2 is multiplexed with rc1 when ccp2mx is set.
? 2004 microchip technology inc. ds39609b-page 3 pic18f6520/8520/6620/8620/6720/8720 pin diagrams (continued) pic18f8620 3 4 5 6 7 8 9 10 11 12 13 14 15 16 48 47 46 45 44 43 42 41 40 39 64 63 62 61 21 22 23 24 25 26 27 28 29 30 31 32 re2/cs /ad10 (3) re3/ad11 re4/ad12 re5/ad13 re6/ad14 re7/ccp2/ad15 (2) rd0/psp0/ad0 (3) v dd v ss rd1/psp1/ad1 (3) rd2/psp2/ad2 (3) rd3/psp3/ad3 (3) rd4/psp4/ad4 (3) rd5/psp5/ad5 (3) rd6/psp6/ad6 (3) rd7/psp7/ad7 (3) re1/wr /ad9 (3) re0/rd /ad8 (3) rg0/ccp3 rg1/tx2/ck2 rg2/rx2/dt2 rg3/ccp4 mclr /v pp rg4/ccp5 v ss v dd rf7/ss rf6/an11 rf5/an10/cv ref rf4/an9 rf3/an8 rf2/an7/c1out rb0/int0 rb1/int1 rb2/int2 rb3/int3/ccp2 (1) rb4/kbi0 rb5/kbi1/pgm rb6/kbi2/pgc v ss osc2/clko/ra6 osc1/clki v dd rb7/kbi3/pgd rc4/sdi/sda rc3/sck/scl rc2/ccp1 rf0/an5 rf1/an6/c2out av dd av ss ra3/an3/v ref + ra2/an2/v ref - ra1/an1 ra0/an0 v ss v dd ra4/t0cki ra5/an4/lvdin rc1/t1osi/ccp2 (1) rc7/rx1/dt1 rc6/tx1/ck1 rc5/sdo rj0/ale rj1/oe rh1/a17 rh0/a16 1 2 rh2/a18 rh3/a19 17 18 rh7/an15 rh6/an14 rh5/an13 rh4/an12 rj5/ce rj4/ba0 37 rj7/ub rj6/lb 50 49 rj2/wrl rj3/wrh 19 20 33 34 35 36 38 58 57 56 55 54 53 52 51 60 59 68 67 66 65 72 71 70 69 74 73 78 77 76 75 79 80 80-pin tqfp pic18f8720 rc0/t1oso/t13cki pic18f8520 note 1: ccp2 is multiplexed with rc1 when ccp2mx is set. 2: ccp2 is multiplexed by default with re7 when the device is configured in microcontroller mode. 3: psp is available only in microcontroller mode.
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 4 ? 2004 microchip technology inc. table of contents 1.0 device overview ............................................................................................................. ............................................................. 7 2.0 oscillator configurations ................................................................................................... ......................................................... 21 3.0 reset ....................................................................................................................... ................................................................... 29 4.0 memory organization ......................................................................................................... ........................................................ 39 5.0 flash program memory........................................................................................................ ...................................................... 61 6.0 external memory interface ................................................................................................... ...................................................... 71 7.0 data eeprom memory .......................................................................................................... ................................................... 79 8.0 8 x 8 hardware multiplier ................................................................................................... ........................................................ 85 9.0 interrupts .................................................................................................................. .................................................................. 87 10.0 i/o ports .................................................................................................................. ................................................................. 103 11.0 timer0 module .............................................................................................................. ........................................................... 131 12.0 timer1 module .............................................................................................................. ........................................................... 135 13.0 timer2 module .............................................................................................................. ........................................................... 141 14.0 timer3 module .............................................................................................................. ........................................................... 143 15.0 timer4 module .............................................................................................................. ........................................................... 147 16.0 capture/compare/pwm (ccp) modules .......................................................................................... ....................................... 149 17.0 master synchronous serial port (mssp) module ............................................................................... ..................................... 157 18.0 addressable universal synchronous asynchr onous receiver transmitter (usart)................................................ .............. 197 19.0 10-bit analog-to-digital converter (a/d) module ............................................................................ ......................................... 213 20.0 comparator module.......................................................................................................... ........................................................ 223 21.0 comparator voltage reference module ........................................................................................ ........................................... 229 22.0 low-voltage detect ......................................................................................................... ......................................................... 233 23.0 special features of the cpu ................................................................................................ .................................................... 239 24.0 instruction set summary .................................................................................................... ...................................................... 259 25.0 development support........................................................................................................ ....................................................... 301 26.0 electrical characteristics ................................................................................................. ......................................................... 307 27.0 dc and ac characteristics graphs and tables ................................................................................ ....................................... 343 28.0 packaging information...................................................................................................... ........................................................ 357 appendix a: revision history................................................................................................... .......................................................... 361 appendix b: device differences................................................................................................. ........................................................ 361 appendix c: conversion considerations .......................................................................................... ................................................. 362 appendix d: migration from mid-range to enhanced devices ....................................................................... ................................... 362 appendix e: migration from high-end to enhanced devices........................................................................ ..................................... 363 index .......................................................................................................................... ........................................................................ 365 on-line support................................................................................................................ ................................................................. 375 systems information and upgrade hot line ....................................................................................... ............................................... 375 reader response ................................................................................................................ .............................................................. 376 pic18f6520/8520/6620/8620/6720/8720 product identification system .............................................................. ............................ 377
? 2004 microchip technology inc. ds39609b-page 5 pic18f6520/8520/6620/8620/6720/8720 to our valued customers it is our intention to provide our valued customers with the best documentation possible to ensure successful use of your micro chip products. to this end, we will continue to improve our publications to better suit your needs. our publications will be refined and enhanced as new volumes and updates are introduced. if you have any questions or comments regar ding this publication, please contact the marketing communications department via e-mail at docerrors@mail.microchip.com or fax the reader response form in the back of this data sheet to (480) 792-4150. we welcome your feedback. most current data sheet to obtain the most up-to-date version of this data s heet, please register at our worldwide web site at: http://www.microchip.com you can determine the version of a data sheet by examining its literature number found on the bottom outside corner of any page . the last character of the literature number is the vers ion number, (e.g., ds30000a is version a of document ds30000). errata an errata sheet, describing minor operational differences fr om the data sheet and recommended workarounds, may exist for curren t devices. as device/doc umentation issues become known to us, we will publis h an errata sheet. the errata will specify the revisi on of silicon and revision of document to which it applies. to determine if an errata sheet exists for a particul ar device, please check with one of the following: microchip?s worldwide web site; http://www.microchip.com your local microchip sales office (see last page) the microchip corporate literatu re center; u.s. fax: (480) 792-7277 when contacting a sales office or the literature center, pleas e specify which device, revisi on of silicon and data sheet (inclu de liter- ature number) you are using. customer notification system register on our web site at www.microchip.com/cn to receive the most current information on all of our products.
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 6 ? 2004 microchip technology inc. notes:
? 2004 microchip technology inc. ds39609b-page 7 pic18f6520/8520/6620/8620/6720/8720 1.0 device overview this document contains device specific information for the following devices: this family offers the same advantages of all pic18 microcontrollers ? namely, high computational performance at an economical price ? with the addition of high endurance enhanced flash program memory. the pic18fxx20 family also provides an enhanced range of program memory options and versatile analog features that make it ideal for complex, high-performance applications. 1.1 key features 1.1.1 expanded memory the pic18fxx20 family introduces the widest range of on-chip, enhanced flash program memory available on picmicro ? microcontrollers ? up to 128 kbyte (or 65,536 words), the largest ever offered by microchip. for users with more modest code requirements, the family also includes members with 32 kbyte or 64 kbyte. other memory features are: data ram and data eeprom: the pic18fxx20 family also provides plenty of room for application data. depending on the device, either 2048 or 3840 bytes of data ram are available. all devices have 1024 bytes of data eeprom for long-term retention of nonvolatile data. memory endurance: the enhanced flash cells for both program memory and data eeprom are rated to last for many thousands of erase/write cycles ? up to 100,000 for program memory and 1,000,000 for eeprom. data retention without refresh is conservatively estimated to be greater than 40 years. 1.1.2 external memory interface in the event that 128 kbytes of program memory is inadequate for an application, the pic18f8x20 members of the family also implement an external memory interface. this allows the controller?s internal program counter to address a memory space of up to 2 mbytes, permitting a level of data access that few 8-bit devices can claim. with the addition of new operating modes, the external memory interface offers many new options, including: operating the microcontroller entirely from external memory using combinations of on-chip and external memory, up to the 2-mbyte limit using external flash memory for reprogrammable application code, or large data tables using external ram devices for storing large amounts of variable data 1.1.3 easy migration regardless of the memory size, all devices share the same rich set of peripherals, allowing for a smooth migration path as applications grow and evolve. the consistent pinout scheme used throughout the entire family also aids in migrating to the next larger device. this is true when moving between the 64-pin members, between the 80-pin members, or even jumping from 64-pin to 80-pin devices. 1.1.4 other special features communications: the pic18fxx20 family incorporates a range of serial communications peripherals, including 2 independent usarts and a master ssp module, capable of both spi and i 2 c (master and slave) modes of operation. for pic18f8x20 devices, one of the general purpose i/o ports can be reconfigured as an 8-bit parallel slave port for direct processor-to-processor communications. ccp modules: all devices in the family incorporate five capture/compare/pwm modules to maximize flexibility in control applications. up to four different time bases may be used to perform several different operations at once. analog features: all devices in the family feature 10-bit a/d converters, with up to 16 input channels, as well as the ability to perform conversions during sleep mode. also included are dual analog comparators with programmable input and output configuration, a programmable low-voltage detect module and a programmable brown-out reset module. self-programmability: these devices can write to their own program memory spaces under inter- nal software control. by using a bootloader routine located in the protected boot block at the top of program memory, it becomes possible to create an application that can update itself in the field. pic18f6520 pic18f8520 pic18f6620 pic18f8620 pic18f6720 pic18f8720
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 8 ? 2004 microchip technology inc. 1.2 details on individual family members the pic18fxx20 devices are available in 64-pin and 80-pin packages. they are differentiated from each other in five ways: 1. flash program memory (32 kbytes for pic18fx520 devices, 64 kbytes for pic18fx620 devices and 128 kbytes for pic18fx720 devices) 2. data ram (2048 bytes for pic18fx520 devices, 3840 bytes for pic18fx620 and pic18fx720 devices) 3. a/d channels (12 for pic18f6x20 devices, 16 for pic18f8x20) 4. i/o pins (52 on pic18f6x20 devices, 68 on pic18f8x20) 5. external program memory interface (present only on pic18f8x20 devices) all other features for devices in the pic18fxx20 family are identical. these are summarized in table 1-1. block diagrams of the pic18f6x20 and pic18f8x20 devices are provided in figure 1-1 and figure 1-2, respectively. the pinouts for these device families are listed in table 1-2. table 1-1: pic18fxx20 device features features pic18f6520 pic18f6620 pic18f6720 pic18f8520 pic18f8620 pic18f8720 operating frequency dc ? 40 mhz dc ? 25 mhz dc ? 25 mhz dc ? 40 mhz dc ? 25 mhz dc ? 25 mhz program memory (bytes) 32k 64k 128k 32k 64k 128k program memory (instructions) 16384 32768 65536 16384 32768 65536 data memory (bytes) 2048 3840 3840 2048 3840 3840 data eeprom memory (bytes) 1024 1024 1024 1024 1024 1024 external memory interface no no no yes yes yes interrupt sources 17 17 17 18 18 18 i/o ports ports a, b, c, d, e, f, g ports a, b, c, d, e, f, g ports a, b, c, d, e, f, g ports a, b, c, d, e, f, g, h, j ports a, b, c, d, e, f, g, h, j ports a, b, c, d, e, f, g, h, j timers 5 5 5 5 5 5 capture/compare/ pwm modules 55 5 555 serial communications mssp, addressable usart (2) mssp, addressable usart (2) mssp, addressable usart (2) mssp, addressable usart (2) mssp, addressable usart (2) mssp, addressable usart (2) parallel communications psp psp psp psp psp psp 10-bit analog-to-digital module 12 input channels 12 input channels 12 input channels 16 input channels 16 input channels 16 input channels resets (and delays) por, bor, reset instruction, stack full, stack underflow (pwrt, ost) por, bor, reset instruction, stack full, stack underflow (pwrt, ost) por, bor, reset instruction, stack full, stack underflow (pwrt, ost) por, bor, reset instruction, stack full, stack underflow (pwrt, ost) por, bor, reset instruction, stack full, stack underflow (pwrt, ost) por, bor, reset instruction, stack full, stack underflow (pwrt, ost) programmable low-voltage detect yes yes yes yes yes yes programmable brown-out reset yes yes yes yes yes yes instruction set 77 instructions 77 instructions 77 inst ructions 77 instructions 77 instructions 77 instructions package 64-pin tqfp 64-pin tqfp 64-pin tqfp 80-pin tqfp 80-pin tqfp 80-pin tqfp
? 2004 microchip technology inc. ds39609b-page 9 pic18f6520/8520/6620/8620/6720/8720 figure 1-1: pic18f6x20 block diagram power-up timer oscillator start-up timer power-on reset watchdog timer instruction decode & control osc1/clki osc2/clko mclr / v pp v dd , v ss porta portb portc ra4/t0cki ra5/an4/lvdin rb0/int0 rc0/t1oso/t13cki rc1/t1osi/ccp2 rc2/ccp1 rc3/sck/scl rc4/sdi/sda rc5/sdo rc6/tx1/ck1 rc7/rx1/dt1 brown-out reset usart1 comparator synchronous bor serial port ra3/an3/v ref + ra2/an2/v ref - ra1/an1 ra0/an0 timing generation rb1/int1 data latch data ram address latch address<12> 12 bank0, f bsr fsr0 fsr1 fsr2 inc/dec logic decode 4 12 4 pch pcl pclath 8 31 level stack program counter prodl prodh 8 x 8 multiply wreg 8 bitop 8 8 alu<8> 8 address latch program memory data latch 21 21 16 8 8 8 table pointer<21> inc/dec logic 21 8 data bus<8> table latch 8 ir 12 3 rom latch portd rd7/psp7:rd0/psp0 rb2/int2 rb3/int3 pclatu pcu precision reference band gap porte portf portg rg0/ccp3 rg1/tx2/ck2 rg2/rx2/dt2 rg3/ccp4 rg4/ccp5 rf7/ss re6 re7/ccp2 re5 re4 re3 re2/cs re0/rd re1/wr lvd ra6 timer0 timer1 timer2 timer3 timer4 ccp1 ccp2 ccp3 ccp4 ccp5 usart2 10-bit a/d rf6/an11 rf5/an10/cv ref rf4/an9 rf3/an8 rf2/an7/c1out rf0/an5 rf1/an6/c2out rb4/kbi0 rb5/kbi1/pgm rb6/kbi2/pgc rb7/kbi3/pgd data eeprom
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 10 ? 2004 microchip technology inc. figure 1-2: pic18f8x20 block diagram power-up timer oscillator start-up timer power-on reset watchdog timer instruction decode & control osc1/clki osc2/clko mclr / v pp v dd , v ss porta portb portc ra4/t0cki ra5/an4/lvdin rc0/t1oso/t13cki rc1/t1osi/ccp2 rc2/ccp1 rc3/sck/scl rc4/sdi/sda rc5/sdo rc6/tx1/ck1 rc7/rx1/dt1 brown-out reset usart1 comparator synchronous bor serial port ra3/an3/v ref + ra2/an2/v ref - ra1/an1 ra0/an0 timing generation 10-bit a/d data latch data ram address latch address<12> 12 bank0, f bsr fsr0 fsr1 fsr2 inc/dec logic decode 4 12 4 pch pcl pclath 8 31 level stack program counter prodl prodh 8 x 8 multiply wreg 8 bitop 8 8 alu<8> 8 address latch program memory data latch 21 21 16 8 8 8 table pointer<21> inc/dec logic 21 8 data bus<8> table latch 8 ir 12 3 rom latch portd rd7/psp7/ad7: pclatu pcu precision reference band gap porte portf portg rg0/ccp3 rg1/tx2/ck2 rg2/rx2/dt2 rg3/ccp4 rg4/ccp5 rf7/ss re6/ad14 re7/ccp2/ad15 re5/ad13 re4/ad12 re3/ad11 re2/cs /ad10 re0/rd /ad8 re1/wr /ad9 lvd porth portj rj0/ale rj1/oe rj2/wrl rj3/wrh ra6 timer0 timer1 timer2 timer3 timer4 ccp1 ccp2 ccp3 ccp4 ccp5 usart2 system bus interface ad15:ad0, a19:a16 (1) note 1: external memory interface pins are physically multiplexed with portd (ad7:ad0), porte (ad15:ad8) and porth (a19:a16). rb0/int0 rb1/int1 rb2/int2 rb3/int3/ccp2 rb4/kbi0 rb5/kbi1/pgm rb6/kbi2/pgc rb7/kbi3/pgd rh7/an15:rh4/an12 rh3/ad19:rh0/ad16 rj4/ba0 rj5/ce rj6/lb rj7/ub rf6/an11 rf5/an10/cv ref rf4/an9 rf3/an8 rf2/an7/c1out rf0/an5 rf1/an6/c2out data eeprom rd0/psp0/ad0
? 2004 microchip technology inc. ds39609b-page 11 pic18f6520/8520/6620/8620/6720/8720 table 1-2: pic18fxx20 pinout i/o descriptions pin name pin number pin type buffer type description pic18f6x20 pic18f8x20 mclr /v pp mclr v pp 79 i p st master clear (input) or programming voltage (output). master clear (reset) input. this pin is an active-low reset to the device. programming voltage input. osc1/clki osc1 clki 39 49 i i cmos/st cmos oscillator crystal or external clock input. oscillator crystal input or external clock source input. st buffer when configured in rc mode; otherwise cmos. external clock source input. always associated with pin function osc1 (see osc1/clki, osc2/clko pins). osc2/clko/ra6 osc2 clko ra6 40 50 o o i/o ? ? ttl oscillator crystal or clock output. oscillator crystal output. connects to crystal or resonator in crystal oscillator mode. in rc mode, osc2 pin outputs clko, which has 1/4 the frequency of osc1 and denotes the instruction cycle rate. general purpose i/o pin. legend: ttl = ttl compatible input cmos = cmos compatible input or output st = schmitt trigger input with cmos levels analog = analog input i = input o = output p = power od = open-drain (no p diode to v dd ) note 1: alternate assignment for ccp2 when ccp2mx is not selected (all operating modes except microcontroller). 2: default assignment when ccp2mx is set. 3: external memory interface functions are only available on pic18f8x20 devices. 4: ccp2 is multiplexed with this pin by default when configured in microcontroller mode. otherwise, it is multiplexed with either rb3 or rc1. 5: porth and portj are only available on pic18f8x20 (80-pin) devices. 6: av dd must be connected to a positive supply and av ss must be connected to a ground reference for proper operation of the part in user or icsp modes. see parameter d001a for details.
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 12 ? 2004 microchip technology inc. porta is a bidirectional i/o port. ra0/an0 ra0 an0 24 30 i/o i ttl analog digital i/o. analog input 0. ra1/an1 ra1 an1 23 29 i/o i ttl analog digital i/o. analog input 1. ra2/an2/v ref - ra2 an2 v ref - 22 28 i/o i i ttl analog analog digital i/o. analog input 2. a/d reference voltage (low) input. ra3/an3/v ref + ra3 an3 v ref + 21 27 i/o i i ttl analog analog digital i/o. analog input 3. a/d reference voltage (high) input. ra4/t0cki ra4 t0cki 28 34 i/o i st/od st digital i/o ? open-drain when configured as output. timer0 external clock input. ra5/an4/lvdin ra5 an4 lvdin 27 33 i/o i i ttl analog analog digital i/o. analog input 4. low-voltage detect input. ra6 see the osc2/clko/ra6 pin. table 1-2: pic18fxx20 pinout i/o descriptions (continued) pin name pin number pin type buffer type description pic18f6x20 pic18f8x20 legend: ttl = ttl compatible input cmos = cmos compatible input or output st = schmitt trigger input with cmos levels analog = analog input i = input o = output p = power od = open-drain (no p diode to v dd ) note 1: alternate assignment for ccp2 when ccp2mx is not selected (all operating modes except microcontroller). 2: default assignment when ccp2mx is set. 3: external memory interface functions are only available on pic18f8x20 devices. 4: ccp2 is multiplexed with this pin by default when configured in microcontroller mode. otherwise, it is multiplexed with either rb3 or rc1. 5: porth and portj are only available on pic18f8x20 (80-pin) devices. 6: av dd must be connected to a positive supply and av ss must be connected to a ground reference for proper operation of the part in user or icsp modes. see parameter d001a for details.
? 2004 microchip technology inc. ds39609b-page 13 pic18f6520/8520/6620/8620/6720/8720 portb is a bidirectional i/o port. portb can be software programmed for internal weak pull-ups on all inputs. rb0/int0 rb0 int0 48 58 i/o i ttl st digital i/o. external interrupt 0. rb1/int1 rb1 int1 47 57 i/o i ttl st digital i/o. external interrupt 1. rb2/int2 rb2 int2 46 56 i/o i ttl st digital i/o. external interrupt 2. rb3/int3/ccp2 rb3 int3 ccp2 (1) 45 55 i/o i/o i/o ttl st st digital i/o. external interrupt 3. capture2 input, compare2 output, pwm2 output. rb4/kbi0 rb4 kbi0 44 54 i/o i ttl st digital i/o. interrupt-on-change pin. rb5/kbi1/pgm rb5 kbi1 pgm 43 53 i/o i i/o ttl st st digital i/o. interrupt-on-change pin. low-voltage icsp programming enable pin. rb6/kbi2/pgc rb6 kbi2 pgc 42 52 i/o i i/o ttl st st digital i/o. interrupt-on-change pin. in-circuit debugger and icsp programming clock. rb7/kbi3/pgd rb7 kbi3 pgd 37 47 i/o i/o ttl st digital i/o. interrupt-on-change pin. in-circuit debugger and icsp programming data. table 1-2: pic18fxx20 pinout i/o descriptions (continued) pin name pin number pin type buffer type description pic18f6x20 pic18f8x20 legend: ttl = ttl compatible input cmos = cmos compatible input or output st = schmitt trigger input with cmos levels analog = analog input i = input o = output p = power od = open-drain (no p diode to v dd ) note 1: alternate assignment for ccp2 when ccp2mx is not selected (all operating modes except microcontroller). 2: default assignment when ccp2mx is set. 3: external memory interface functions are only available on pic18f8x20 devices. 4: ccp2 is multiplexed with this pin by default when configured in microcontroller mode. otherwise, it is multiplexed with either rb3 or rc1. 5: porth and portj are only available on pic18f8x20 (80-pin) devices. 6: av dd must be connected to a positive supply and av ss must be connected to a ground reference for proper operation of the part in user or icsp modes. see parameter d001a for details.
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 14 ? 2004 microchip technology inc. portc is a bidirectional i/o port. rc0/t1oso/t13cki rc0 t1oso t13cki 30 36 i/o o i st ? st digital i/o. timer1 oscillator output. timer1/timer3 external clock input. rc1/t1osi/ccp2 rc1 t1osi ccp2 (2) 29 35 i/o i i/o st cmos st digital i/o. timer1 oscillator input. capture2 input/compare2 output/ pwm2 output. rc2/ccp1 rc2 ccp1 33 43 i/o i/o st st digital i/o. capture1 input/compare1 output/ pwm1 output. rc3/sck/scl rc3 sck scl 34 44 i/o i/o i/o st st st digital i/o. synchronous serial clock input/output for spi mode. synchronous serial clock input/output for i 2 c mode. rc4/sdi/sda rc4 sdi sda 35 45 i/o i i/o st st st digital i/o. spi data in. i 2 c data i/o. rc5/sdo rc5 sdo 36 46 i/o o st ? digital i/o. spi data out. rc6/tx1/ck1 rc6 tx1 ck1 31 37 i/o o i/o st ? st digital i/o. usart 1 asynchronous transmit. usart 1 synchronous clock (see rx1/dt1). rc7/rx1/dt1 rc7 rx1 dt1 32 38 i/o i i/o st st st digital i/o. usart 1 asynchronous receive. usart 1 synchronous data (see tx1/ck1). table 1-2: pic18fxx20 pinout i/o descriptions (continued) pin name pin number pin type buffer type description pic18f6x20 pic18f8x20 legend: ttl = ttl compatible input cmos = cmos compatible input or output st = schmitt trigger input with cmos levels analog = analog input i = input o = output p = power od = open-drain (no p diode to v dd ) note 1: alternate assignment for ccp2 when ccp2mx is not selected (all operating modes except microcontroller). 2: default assignment when ccp2mx is set. 3: external memory interface functions are only available on pic18f8x20 devices. 4: ccp2 is multiplexed with this pin by default when configured in microcontroller mode. otherwise, it is multiplexed with either rb3 or rc1. 5: porth and portj are only available on pic18f8x20 (80-pin) devices. 6: av dd must be connected to a positive supply and av ss must be connected to a ground reference for proper operation of the part in user or icsp modes. see parameter d001a for details.
? 2004 microchip technology inc. ds39609b-page 15 pic18f6520/8520/6620/8620/6720/8720 portd is a bidirectional i/o port. these pins have ttl input buffers when external memory is enabled. rd0/psp0/ad0 rd0 psp0 ad0 (3) 58 72 i/o i/o i/o st ttl ttl digital i/o. parallel slave port data. external memory address/data 0. rd1/psp1/ad1 rd1 psp1 ad1 (3) 55 69 i/o i/o i/o st ttl ttl digital i/o. parallel slave port data. external memory address/data 1. rd2/psp2/ad2 rd2 psp2 ad2 (3) 54 68 i/o i/o i/o st ttl ttl digital i/o. parallel slave port data. external memory address/data 2. rd3/psp3/ad3 rd3 psp3 ad3 (3) 53 67 i/o i/o i/o st ttl ttl digital i/o. parallel slave port data. external memory address/data 3. rd4/psp4/ad4 rd4 psp4 ad4 (3) 52 66 i/o i/o i/o st ttl ttl digital i/o. parallel slave port data. external memory address/data 4. rd5/psp5/ad5 rd5 psp5 ad5 (3) 51 65 i/o i/o i/o st ttl ttl digital i/o. parallel slave port data. external memory address/data 5. rd6/psp6/ad6 rd6 psp6 ad6 (3) 50 64 i/o i/o i/o st ttl ttl digital i/o. parallel slave port data. external memory address/data 6. rd7/psp7/ad7 rd7 psp7 ad7 (3) 49 63 i/o i/o i/o st ttl ttl digital i/o. parallel slave port data. external memory address/data 7. table 1-2: pic18fxx20 pinout i/o descriptions (continued) pin name pin number pin type buffer type description pic18f6x20 pic18f8x20 legend: ttl = ttl compatible input cmos = cmos compatible input or output st = schmitt trigger input with cmos levels analog = analog input i = input o = output p = power od = open-drain (no p diode to v dd ) note 1: alternate assignment for ccp2 when ccp2mx is not selected (all operating modes except microcontroller). 2: default assignment when ccp2mx is set. 3: external memory interface functions are only available on pic18f8x20 devices. 4: ccp2 is multiplexed with this pin by default when configured in microcontroller mode. otherwise, it is multiplexed with either rb3 or rc1. 5: porth and portj are only available on pic18f8x20 (80-pin) devices. 6: av dd must be connected to a positive supply and av ss must be connected to a ground reference for proper operation of the part in user or icsp modes. see parameter d001a for details.
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 16 ? 2004 microchip technology inc. porte is a bidirectional i/o port. re0/rd /ad8 re0 rd ad8 (3) 24 i/o i i/o st ttl ttl digital i/o. read control for parallel slave port (see w r and cs pins). external memory address/data 8. re1/wr /ad9 re1 wr ad9 (3) 13 i/o i i/o st ttl ttl digital i/o. write control for parallel slave port (see c s and rd pins). external memory address/data 9. re2/cs /ad10 re2 cs ad10 (3) 64 78 i/o i i/o st ttl ttl digital i/o. chip select control for parallel slave port (see rd and wr ). external memory address/data 10. re3/ad11 re3 ad11 (3) 63 77 i/o i/o st ttl digital i/o. external memory address/data 11. re4/ad12 re4 ad12 62 76 i/o i/o st ttl digital i/o. external memory address/data 12. re5/ad13 re5 ad13 (3) 61 75 i/o i/o st ttl digital i/o. external memory address/data 13. re6/ad14 re6 ad14 (3) 60 74 i/o i/o st ttl digital i/o. external memory address/data 14. re7/ccp2/ad15 re7 ccp2 (1,4) ad15 (3) 59 73 i/o i/o i/o st st ttl digital i/o. capture2 input/compare2 output/ pwm2 output. external memory address/data 15. table 1-2: pic18fxx20 pinout i/o descriptions (continued) pin name pin number pin type buffer type description pic18f6x20 pic18f8x20 legend: ttl = ttl compatible input cmos = cmos compatible input or output st = schmitt trigger input with cmos levels analog = analog input i = input o = output p = power od = open-drain (no p diode to v dd ) note 1: alternate assignment for ccp2 when ccp2mx is not selected (all operating modes except microcontroller). 2: default assignment when ccp2mx is set. 3: external memory interface functions are only available on pic18f8x20 devices. 4: ccp2 is multiplexed with this pin by default when configured in microcontroller mode. otherwise, it is multiplexed with either rb3 or rc1. 5: porth and portj are only available on pic18f8x20 (80-pin) devices. 6: av dd must be connected to a positive supply and av ss must be connected to a ground reference for proper operation of the part in user or icsp modes. see parameter d001a for details.
? 2004 microchip technology inc. ds39609b-page 17 pic18f6520/8520/6620/8620/6720/8720 portf is a bidirectional i/o port. rf0/an5 rf0 an5 18 24 i/o i st analog digital i/o. analog input 5. rf1/an6/c2out rf1 an6 c2out 17 23 i/o i o st analog st digital i/o. analog input 6. comparator 2 output. rf2/an7/c1out rf2 an7 c1out 16 18 i/o i o st analog st digital i/o. analog input 7. comparator 1 output. rf3/an8 rf1 an8 15 17 i/o i st analog digital i/o. analog input 8. rf4/an9 rf1 an9 14 16 i/o i st analog digital i/o. analog input 9. rf5/an10/cv ref rf1 an10 cv ref 13 15 i/o i o st analog analog digital i/o. analog input 10. comparator v ref output. rf6/an11 rf6 an11 12 14 i/o i st analog digital i/o. analog input 11. rf7/ss rf7 ss 11 13 i/o i st ttl digital i/o. spi slave select input. table 1-2: pic18fxx20 pinout i/o descriptions (continued) pin name pin number pin type buffer type description pic18f6x20 pic18f8x20 legend: ttl = ttl compatible input cmos = cmos compatible input or output st = schmitt trigger input with cmos levels analog = analog input i = input o = output p = power od = open-drain (no p diode to v dd ) note 1: alternate assignment for ccp2 when ccp2mx is not selected (all operating modes except microcontroller). 2: default assignment when ccp2mx is set. 3: external memory interface functions are only available on pic18f8x20 devices. 4: ccp2 is multiplexed with this pin by default when configured in microcontroller mode. otherwise, it is multiplexed with either rb3 or rc1. 5: porth and portj are only available on pic18f8x20 (80-pin) devices. 6: av dd must be connected to a positive supply and av ss must be connected to a ground reference for proper operation of the part in user or icsp modes. see parameter d001a for details.
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 18 ? 2004 microchip technology inc. portg is a bidirectional i/o port. rg0/ccp3 rg0 ccp3 35 i/o i/o st st digital i/o. capture3 input/compare3 output/ pwm3 output. rg1/tx2/ck2 rg1 tx2 ck2 46 i/o o i/o st ? st digital i/o. usart 2 asynchronous transmit. usart 2 synchronous clock (see rx2/dt2). rg2/rx2/dt2 rg2 rx2 dt2 57 i/o i i/o st st st digital i/o. usart 2 asynchronous receive. usart 2 synchronous data (see tx2/ck2). rg3/ccp4 rg3 ccp4 68 i/o i/o st st digital i/o. capture4 input/compare4 output/ pwm4 output. rg4/ccp5 rg4 ccp5 810 i/o i/o st st digital i/o. capture5 input/compare5 output/ pwm5 output. table 1-2: pic18fxx20 pinout i/o descriptions (continued) pin name pin number pin type buffer type description pic18f6x20 pic18f8x20 legend: ttl = ttl compatible input cmos = cmos compatible input or output st = schmitt trigger input with cmos levels analog = analog input i = input o = output p = power od = open-drain (no p diode to v dd ) note 1: alternate assignment for ccp2 when ccp2mx is not selected (all operating modes except microcontroller). 2: default assignment when ccp2mx is set. 3: external memory interface functions are only available on pic18f8x20 devices. 4: ccp2 is multiplexed with this pin by default when configured in microcontroller mode. otherwise, it is multiplexed with either rb3 or rc1. 5: porth and portj are only available on pic18f8x20 (80-pin) devices. 6: av dd must be connected to a positive supply and av ss must be connected to a ground reference for proper operation of the part in user or icsp modes. see parameter d001a for details.
? 2004 microchip technology inc. ds39609b-page 19 pic18f6520/8520/6620/8620/6720/8720 porth is a bidirectional i/o port (5) . rh0/a16 rh0 a16 ?79 i/o o st ttl digital i/o. external memory address 16. rh1/a17 rh1 a17 ?80 i/o o st ttl digital i/o. external memory address 17. rh2/a18 rh2 a18 ?1 i/o o st ttl digital i/o. external memory address 18. rh3/a19 rh3 a19 ?2 i/o o st ttl digital i/o. external memory address 19. rh4/an12 rh4 an12 ?22 i/o i st analog digital i/o. analog input 12. rh5/an13 rh5 an13 ?21 i/o i st analog digital i/o. analog input 13. rh6/an14 rh6 an14 ?20 i/o i st analog digital i/o. analog input 14. rh7/an15 rh7 an15 ?19 i/o i st analog digital i/o. analog input 15. table 1-2: pic18fxx20 pinout i/o descriptions (continued) pin name pin number pin type buffer type description pic18f6x20 pic18f8x20 legend: ttl = ttl compatible input cmos = cmos compatible input or output st = schmitt trigger input with cmos levels analog = analog input i = input o = output p = power od = open-drain (no p diode to v dd ) note 1: alternate assignment for ccp2 when ccp2mx is not selected (all operating modes except microcontroller). 2: default assignment when ccp2mx is set. 3: external memory interface functions are only available on pic18f8x20 devices. 4: ccp2 is multiplexed with this pin by default when configured in microcontroller mode. otherwise, it is multiplexed with either rb3 or rc1. 5: porth and portj are only available on pic18f8x20 (80-pin) devices. 6: av dd must be connected to a positive supply and av ss must be connected to a ground reference for proper operation of the part in user or icsp modes. see parameter d001a for details.
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 20 ? 2004 microchip technology inc. portj is a bidirectional i/o port (5) . rj0/ale rj0 ale ?62 i/o o st ttl digital i/o. external memory address latch enable. rj1/oe rj1 oe ?61 i/o o st ttl digital i/o. external memory output enable. rj2/wrl rj2 wrl ?60 i/o o st ttl digital i/o. external memory write low control. rj3/wrh rj3 wrh ?59 i/o o st ttl digital i/o. external memory write high control. rj4/ba0 rj4 ba0 ?39 i/o o st ttl digital i/o. external memory byte address 0 control. rj5/ce rj5 ce ?40 i/o o st ttl digital i/o. external memory chip enable control. rj6/lb rj6 lb ?41 i/o o st ttl digital i/o. external memory low byte select. rj7/ub rj7 ub ?42 i/o o st ttl digital i/o. external memory high byte select. v ss 9, 25, 41, 56 11, 31, 51, 70 p ? ground reference for logic and i/o pins. v dd 10, 26, 38, 57 12, 32, 48, 71 p ? positive supply for logic and i/o pins. av ss (6) 20 26 p ? ground reference for analog modules. av dd (6) 19 25 p ? positive supply for analog modules. table 1-2: pic18fxx20 pinout i/o descriptions (continued) pin name pin number pin type buffer type description pic18f6x20 pic18f8x20 legend: ttl = ttl compatible input cmos = cmos compatible input or output st = schmitt trigger input with cmos levels analog = analog input i = input o = output p = power od = open-drain (no p diode to v dd ) note 1: alternate assignment for ccp2 when ccp2mx is not selected (all operating modes except microcontroller). 2: default assignment when ccp2mx is set. 3: external memory interface functions are only available on pic18f8x20 devices. 4: ccp2 is multiplexed with this pin by default when configured in microcontroller mode. otherwise, it is multiplexed with either rb3 or rc1. 5: porth and portj are only available on pic18f8x20 (80-pin) devices. 6: av dd must be connected to a positive supply and av ss must be connected to a ground reference for proper operation of the part in user or icsp modes. see parameter d001a for details.
? 2004 microchip technology inc. ds39609b-page 21 pic18f6520/8520/6620/8620/6720/8720 2.0 oscillator configurations 2.1 oscillator types the pic18fxx20 devices can be operated in eight different oscillator modes. the user can program three configuration bits (fosc2, fosc1 and fosc0) to select one of these eight modes: 1. lp low-power crystal 2. xt crystal/resonator 3. hs high-speed crystal/resonator 4. hs+pll high-speed crystal/resonator with pll enabled 5. rc external resistor/capacitor 6. rcio external resistor/capacitor with i/o pin enabled 7. ec external clock 8. ecio external clock with i/o pin enabled 2.2 crystal oscillator/ceramic resonators in xt, lp, hs or hs+pll oscillator modes, a crystal or ceramic resonator is connected to the osc1 and osc2 pins to establish oscillation. figure 2-1 shows the pin connections. the pic18fxx20 oscillator design requires the use of a parallel cut crystal. figure 2-1: crystal/ceramic resonator operation (hs, xt or lp configuration) table 2-1: capacitor selection for ceramic resonators note: use of a series cut crystal may give a fre- quency out of the crystal manufacturer?s specifications. note 1: see table 2-1 and table 2-2 for recommended values of c1 and c2. 2: a series resistor (r s ) may be required for at strip cut crystals. 3: r f varies with the oscillator mode chosen. c1 (1) c2 (1) xtal osc2 osc1 r f (3) sleep to logic pic18fxx20 r s (2) internal ranges tested: mode freq c1 c2 xt 455 khz 2.0 mhz 4.0 mhz 68-100 pf 15-68 pf 15-68 pf 68-100 pf 15-68 pf 15-68 pf hs 8.0 mhz 16.0 mhz 10-68 pf 10-22 pf 10-68 pf 10-22 pf these values are for design guidance only. see notes following this table. resonators used: 2.0 mhz murata erie csa2.00mg 0.5% 4.0 mhz murata erie csa4.00mg 0.5% 8.0 mhz murata erie csa8.00mt 0.5% 16.0 mhz murata erie csa16.00mx 0.5% all resonators used did not have built-in capacitors. note 1: higher capacitance increases the stability of the oscillator, but also increases the start-up time. 2: when operating below 3v v dd , or when using certain ceramic resonators at any voltage, it may be necessary to use high gain hs mode, try a lower frequency resonator, or switch to a crystal oscillator. 3: since each resonator/crystal has its own characteristics, the user should consult the resonator/crystal manufacturer for appropriate values of external components, or verify oscillator performance.
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 22 ? 2004 microchip technology inc. table 2-2: capacitor selection for crystal oscillator an external clock source may also be connected to the osc1 pin in the hs, xt and lp modes, as shown in figure 2-2. figure 2-2: external clock input operation (hs, xt or lp osc configuration) 2.3 rc oscillator for timing insensitive applications, the ?rc? and ?rcio? device options offer additional cost savings. the rc oscillator frequency is a function of the supply voltage, the resistor (r ext ) and capacitor (c ext ) val- ues and the operating temperature. in addition to this, the oscillator frequency will vary from unit to unit, due to normal process parameter variation. furthermore, the difference in lead frame capacitance between pack- age types will also affect the oscillation frequency, especially for low c ext values. the user also needs to take into account variation due to tolerance of external r and c components used. figure 2-3 shows how the r/c combination is connected. in the rc oscillator mode, the oscillator frequency divided by 4 is available on the osc2 pin. this signal may be used for test purposes or to synchronize other logic. figure 2-3: rc oscillator mode the rcio oscillator mode functions like the rc mode, except that the osc2 pin becomes an additional general purpose i/o pin. the i/o pin becomes bit 6 of porta (ra6). ranges tested: mode freq c1 c2 lp 32 khz 15-22 pf 15-22 pf 200 khz xt 1 mhz 15-22 pf 15-22 pf 4 mhz hs 4 mhz 15-22 pf 15-22 pf 8 mhz 20 mhz capacitor values are for design guidance only. these capacitors were tested with the above crystal frequencies for basic start-up and operation. these values are not optimized . different capacitor values may be required to produce acceptable oscillator operation. the user should test the performance of the oscillator over the expected v dd and temperature range for the application. see the notes following this table for additional information. note 1: higher capacitance increases the stability of the oscillator, but also increases the start-up time. 2: when operating below 3v v dd , or when using certain ceramic resonators at any voltage, it may be necessary to use the hs mode or switch to a crystal oscillator. 3: since each resonator/crystal has its own characteristics, the user should consult the resonator/crystal manufac- turer for appropriate values of external components, or verify oscillator performance. 4: r s may be required to avoid overdriving crystals with low drive level specification. 5: always verify oscillator performance over the v dd and temperature range that is expected for the application. osc1 osc2 open clock from ext. system pic18fxx20 osc2/clko c ext r ext pic18fxx20 osc1 f osc /4 internal clock v dd v ss recommended values: 3 k ? r ext 100 k ? c ext > 20 pf
? 2004 microchip technology inc. ds39609b-page 23 pic18f6520/8520/6620/8620/6720/8720 2.4 external clock input the ec and ecio oscillator modes require an external clock source to be connected to the osc1 pin. the feedback device between osc1 and osc2 is turned off in these modes to save current. there is a maximum 1.5 s start-up required after a power-on reset, or wake-up from sleep mode. in the ec oscillator mode, the oscillator frequency divided by 4 is available on the osc2 pin. this signal may be used for test purposes or to synchronize other logic. figure 2-4 shows the pin connections for the ec oscillator mode. figure 2-4: external clock input operation (ec configuration) the ecio oscillator mode functions like the ec mode, except that the osc2 pin becomes an additional gen- eral purpose i/o pin. the i/o pin becomes bit 6 of porta (ra6). figure 2-5 shows the pin connections for the ecio oscillator mode. figure 2-5: external clock input operation (ecio configuration) 2.5 hs/pll a phase locked loop circuit (pll) is provided as a programmable option for users that want to multiply the frequency of the incoming crystal oscillator signal by 4. for an input clock frequency of 10 mhz, the internal clock frequency will be multiplied to 40 mhz. this is useful for customers who are concerned with emi due to high-frequency crystals. the pll is one of the modes of the fosc<2:0> config- uration bits. the oscillator mode is specified during device programming. the pll can only be enabled when the oscillator con- figuration bits are programmed for hs mode. if they are programmed for any other mode, the pll is not enabled and the system clock will come directly from osc1. also, pll operation cannot be changed ?on- the-fly?. to enable or disable it, the controller must either cycle through a power-on reset, or switch the clock source from the main oscillator to the timer1 oscillator and back again. see section 2.6 ?oscillator switching feature? for details on oscillator switching. a pll lock timer is used to ensure that the pll has locked before device execution starts. the pll lock timer has a time-out that is called t pll . figure 2-6: pll block diagram osc1 osc2 f osc /4 clock from ext. system pic18fxx20 osc1 i/o (osc2) ra6 clock from ext. system pic18fxx20 mux vco loop filter divide by 4 crystal osc osc2 osc1 pll enable f in f out sysclk phase comparator (from configuration hs osc bit register)
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 24 ? 2004 microchip technology inc. 2.6 oscillator switching feature the pic18fxx20 devices include a feature that allows the system clock source to be switched from the main oscillator to an alternate low-frequency clock source. for the pic18fxx20 devices, this alternate clock source is the timer1 oscillator. if a low-frequency crystal (32 khz, for example) has been attached to the timer1 oscillator pins and the timer1 oscillator has been enabled, the device can switch to a low-power execution mode. figure 2-7 shows a block diagram of the system clock sources. the clock switching feature is enabled by programming the oscillator switching enable (oscsen ) bit in configuration register 1h to a ? 0 ?. clock switching is disabled in an erased device. see section 12.0 ?timer1 module? for further details of the timer1 oscillator. see section 23.0 ?special features of the cpu? for configuration register details. figure 2-7: device clock sources pic18fxx20 t osc 4 x pll t t 1 p t sclk clock source mux t osc /4 timer1 oscillator t1oscen enable oscillator t1oso t1osi clock source option for other modules osc1 osc2 sleep main oscillator
? 2004 microchip technology inc. ds39609b-page 25 pic18f6520/8520/6620/8620/6720/8720 2.6.1 system clock switch bit the system clock source switching is performed under software control. the system clock switch bit, scs (osccon<0>), controls the clock switching. when the scs bit is ? 0 ?, the system clock source comes from the main oscillator that is selected by the fosc configura- tion bits in configuration register 1h. when the scs bit is set, the system clock source will come from the timer1 oscillator. the scs bit is cleared on all forms of reset. register 2-1: osccon register note: the timer1 oscillator must be enabled and operating to switch the system clock source. the timer1 oscillator is enabled by setting the t1oscen bit in the timer1 control register (t1con). if the timer1 oscillator is not enabled, then any write to the scs bit will be ignored (scs bit forced cleared) and the main oscillator will continue to be the system clock source. u-0 u-0 u-0 u-0 u-0 u-0 u-0 r/w-1 ? ? ? ? ? ? ?scs bit 7 bit 0 bit 7-1 unimplemented: read as ? 0 ? bit 0 scs: system clock switch bit when oscsen configuration bit = 0 and t1oscen bit is set : 1 = switch to timer1 oscillator/clock pin 0 = use primary oscillator/clock input pin when oscsen and t1oscen are in other states : bit is forced clear. legend: r = readable bit w = writable bit u = unimplemented bit, read as ?0? - n = value at por ?1? = bit is set ?0? = bit is cleared x = bit is unknown
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 26 ? 2004 microchip technology inc. 2.6.2 oscillator transitions pic18fxx20 devices contain circuitry to prevent ?glitches? when switching between oscillator sources. essentially, the circuitry waits for eight rising edges of the clock source that the processor is switching to. this ensures that the new clock source is stable and that its pulse width will not be less than the shortest pulse width of the two clock sources. a timing diagram indicating the transition from the main oscillator to the timer1 oscillator is shown in figure 2-8. the timer1 oscillator is assumed to be running all the time. after the scs bit is set, the processor is frozen at the next occurring q1 cycle. after eight synchronization cycles are counted from the timer1 oscillator, operation resumes. no additional delays are required after the synchronization cycles. figure 2-8: timing diagram for transiti on from osc1 to timer1 oscillator the sequence of events that takes place when switch- ing from the timer1 oscillator to the main oscillator will depend on the mode of the main oscillator. in addition to eight clock cycles of the main oscillator, additional delays may take place. if the main oscillator is configured for an external crystal (hs, xt, lp), then the transition will take place after an oscillator start-up time (t ost ) has occurred. a timing diagram, indicating the transition from the timer1 oscillator to the main oscillator for hs, xt and lp modes, is shown in figure 2-9. figure 2-9: timing for transition between timer1 and osc1 (hs, xt, lp) q3 q2 q1 q4 q3 q2 osc1 internal scs (osccon<0>) program pc + 2 pc note 1: delay on internal system clock is eight oscillator cycles for synchronization. q1 t1osi q4 q1 pc + 4 q1 t scs clock counter system q2 q3 q4 q1 t dly t t 1 p t osc 2 1 34 5678 q3 q3 q4 q1 q2 q3 q4 q1 q2 osc1 internal scs (osccon<0>) program pc pc + 2 note 1: t ost = 1024 t osc (drawing not to scale). t1osi system clock osc2 t ost q1 pc + 6 t t 1 p t osc t scs 12345678 counter
? 2004 microchip technology inc. ds39609b-page 27 pic18f6520/8520/6620/8620/6720/8720 if the main oscillator is configured for hs-pll mode, an oscillator start-up time (t ost ), plus an additional pll time-out (t pll ), will occur. the pll time-out is typically 2 ms and allows the pll to lock to the main oscillator frequency. a timing diagram, indicating the transition from the timer1 oscillator to the main oscillator for hs-pll mode, is shown in figure 2-10. figure 2-10: timing for transition between timer1 and osc1 (hs with pll) if the main oscillator is configured in the rc, rcio, ec or ecio modes, there is no oscillator start-up time-out. operation will resume after eight cycles of the main oscillator have been counted. a timing diagram, indicating the transition from the timer1 oscillator to the main oscillator for rc, rcio, ec and ecio modes, is shown in figure 2-11. figure 2-11: timing for transition between timer1 and osc1 (rc, ec) q4 q1 q1 q2 q3 q4 q1 q2 osc1 internal system scs (osccon<0>) program counter pc pc + 2 note 1: t ost = 1024 t osc (drawing not to scale). t1osi clock t ost q3 pc + 4 t pll t osc t t 1 p t scs q4 osc2 pll clock input 1 23 4 56 78 q3 q4 q1 q1 q2 q3 q4 q1 q2 q3 osc1 internal system scs (osccon<0>) program pc pc + 2 note 1: rc oscillator mode assumed. pc + 4 t1osi clock osc2 q4 t t 1 p t osc t scs 1 23 45 6 78 counter
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 28 ? 2004 microchip technology inc. 2.7 effects of sleep mode on the on-chip oscillator when the device executes a sleep instruction, the on- chip clocks and oscillator are turned off and the device is held at the beginning of an instruction cycle (q1 state). with the oscillator off, the osc1 and osc2 signals will stop oscillating. since all the transistor switching currents have been removed, sleep mode achieves the lowest current consumption of the device (only leakage currents). enabling any on-chip feature that will operate during sleep will increase the current consumed during sleep. the user can wake from sleep through external reset, watchdog timer reset or through an interrupt. 2.8 power-up delays power up delays are controlled by two timers so that no external reset circuitry is required for most applications. the delays ensure that the device is kept in reset until the device power supply and clock are stable. for additional information on reset operation, see section 3.0 ?reset? . the first timer is the power-up timer (pwrt), which optionally provides a fixed delay of 72 ms (nominal) on power-up only (por and bor). the second timer is the oscillator start-up timer (ost), intended to keep the chip in reset until the crystal oscillator is stable. with the pll enabled (hs/pll oscillator mode), the time-out sequence following a power-on reset is differ- ent from other oscillator modes. the time-out sequence is as follows: first, the pwrt time-out is invoked after a por time delay has expired. then, the oscillator start-up timer (ost) is invoked. however, this is still not a sufficient amount of time to allow the pll to lock at high frequencies. the pwrt timer is used to provide an additional fixed 2 ms (nominal) time-out to allow the pll ample time to lock to the incoming clock frequency. table 2-3: osc1 and osc2 pin states in sleep mode osc mode osc1 pin osc2 pin rc floating, external resistor should pull high at logic low rcio floating, external resistor should pull high configured as porta, bit 6 ecio floating configured as porta, bit 6 ec floating at logic low lp, xt and hs feedback inverter disabled at quiescent voltage level feedback inverter disabled at quiescent voltage level note: see table 3-1 in section 3.0 ?reset? for time-outs due to sleep and mclr reset.
? 2004 microchip technology inc. ds39609b-page 29 pic18f6520/8520/6620/8620/6720/8720 3.0 reset the pic18fxx20 devices differentiate between various kinds of reset: a) power-on reset (por) b) mclr reset during normal operation c) mclr reset during sleep d) watchdog timer (wdt) reset (during normal operation) e) programmable brown-out reset (pbor) f) reset instruction g) stack full reset h) stack underflow reset most registers are unaffected by a reset. their status is unknown on por and unchanged by all other resets. the other registers are forced to a ?reset state? on power-on reset, mclr , wdt reset, brown- out reset, mclr reset during sleep and by the reset instruction. most registers are not affected by a wdt wake-up, since this is viewed as the resumption of normal operation. status bits from the rcon register, ri , to , pd , por and bor , are set or cleared differently in different reset situations, as indicated in table 3-2. these bits are used in software to determine the nature of the reset. see table 3-3 for a full description of the reset states of all registers. a simplified block diagram of the on-chip reset circuit is shown in figure 3-1. the enhanced mcu devices have a mclr noise filter in the mclr reset path. the filter will detect and ignore small pulses. the mclr pin is not driven low by any internal resets, including the wdt. figure 3-1: simplified block diagram of on-chip reset circuit s r q external reset mclr v dd osc1 wdt module v dd rise detect ost/pwrt on-chip rc osc (1) wdt time-out power-on reset ost 10-bit ripple counter pwrt chip_rese t 10-bit ripple counter reset enable ost (2) enable pwrt sleep note 1: this is a separate oscillator from the rc oscillator of the clki pin. 2: see table 3-1 for time-out situations. brown-out reset boren reset instruction stack pointer stack full/underflow reset
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 30 ? 2004 microchip technology inc. 3.1 power-on reset (por) a power-on reset pulse is generated on-chip when v dd rise is detected. to take advantage of the por circuitry, tie the mclr pin through a 1 k ? to 10 k ? resistor to v dd . this will eliminate external rc components usually needed to create a power-on reset delay. a minimum rise rate for v dd is specified (parameter d004). for a slow rise time, see figure 3-2. when the device starts normal operation (i.e., exits the reset condition), device operating parameters (volt- age, frequency, temperature, etc.) must be met to ensure operation. if these conditions are not met, the device must be held in reset until the operating conditions are met. figure 3-2: external power-on reset circuit (for slow v dd power-up) 3.2 power-up timer (pwrt) the power-up timer provides a fixed nominal time-out (parameter #33) only on power-up from the por. the power-up timer operates on an internal rc oscillator. the chip is kept in reset as long as the pwrt is active. the pwrt?s time delay allows v dd to rise to an accept- able level. a configuration bit is provided to enable/ disable the pwrt. the power-up time delay will vary from chip-to-chip due to v dd , temperature and process variation. see dc parameter #33 for details. 3.3 oscillator start-up timer (ost) the oscillator start-up timer (ost) provides 1024 oscillator cycles (from osc1 input) delay after the pwrt delay is over (parameter #32). this ensures that the crystal oscillator or resonator has started and stabilized. the ost time-out is invoked only for xt, lp and hs modes and only on power-on reset, or wake-up from sleep. 3.4 pll lock time-out with the pll enabled, the time-out sequence following a power-on reset is different from other oscillator modes. a portion of the power-up timer is used to provide a fixed time-out that is sufficient for the pll to lock to the main oscillator frequency. this pll lock time-out (t pll ) is typically 2 ms and follows the oscillator start-up time-out. 3.5 brown-out reset (bor) a configuration bit, boren, can disable (if clear/ programmed), or enable (if set) the brown-out reset circuitry. if v dd falls below parameter d005 for greater than parameter #35, the brown-out situation will reset the chip. a reset may not occur if v dd falls below parameter d005 for less than parameter #35. the chip will remain in brown-out reset until v dd rises above bv dd . if the power-up timer is enabled, it will be invoked after v dd rises above bv dd ; it then will keep the chip in reset for an additional time delay (parame- ter #33). if v dd drops below bv dd while the power-up timer is running, the chip will go back into a brown-out reset and the power-up timer will be initialized. once v dd rises above bv dd , the power-up timer will execute the additional time delay. 3.6 time-out sequence on power-up, the time-out sequence is as follows: first, pwrt time-out is invoked after the por time delay has expired. then, ost is activated. the total time-out will vary based on oscillator configuration and the status of the pwrt. for example, in rc mode with the pwrt disabled, there will be no time-out at all. figures 3-3 through 3-7 depict time-out sequences on power-up. since the time-outs occur from the por pulse, the time-outs will expire if mclr is kept low long enough. bringing mclr high will begin execution immediately (figure 3-5). this is useful for testing purposes, or to synchronize more than one pic18fxx20 device operating in parallel. table 3-2 shows the reset conditions for some special function registers, while table 3-3 shows the reset conditions for all of the registers. note 1: external power-on reset circuit is required only if the v dd power-up slope is too slow . the diode d helps discharge the capacitor quickly when v dd powers down. 2: r < 40 k ? is recommended to make sure tha t the voltage drop across r does not violate the device?s electrical specification. 3: r1 = 1 k ? to 10 k ? will limit any current flow- ing into mclr from external capacitor c, in the event of mclr/ v pp pin breakdown due to electrostatic discharge (esd) or electrica l overstress (eos). c r1 r d v dd mclr pic18fxx20
? 2004 microchip technology inc. ds39609b-page 31 pic18f6520/8520/6620/8620/6720/8720 table 3-1: time-out in various situations register 3-1: rcon register bits and positions table 3-2: status bits, their significanc e and the initialization condition for rcon register oscillator configuration power-up (2) brown-out wake-up from sleep or oscillator switch pwrte = 0 pwrte = 1 hs with pll enabled (1) 72 ms + 1024 t osc + 2ms 1024 t osc + 2 ms 72 ms (2) + 1024 t osc + 2 ms 1024 t osc + 2 ms hs, xt, lp 72 ms + 1024 t osc 1024 t osc 72 ms (2) + 1024 t osc 1024 t osc ec 72 ms 1.5 s72 ms (2) 1.5 s (3) external rc 72 ms ? 72 ms (2) ? note 1: 2 ms is the nominal time required for the 4xpll to lock. 2: 72 ms is the nominal power-up timer delay, if implemented. 3: 1.5 s is the recovery time from sleep. there is no recovery time from oscillator switch. r/w-0 u-0 u-0 r/w-1 r/w-1 r/w-1 r/w-1 r/w-1 ipen ? ?ri to pd por bor bit 7 bit 0 note 1: refer to section 4.14 ?rcon register? for bit definitions. condition program counter rcon register ri to pd por bor stkful stkunf power-on reset 0000h 0--1 1100 1 1 1 0 0 u u mclr reset during normal operation 0000h 0--u uuuu u u u u u u u software reset during normal operation 0000h 0--0 uuuu 0 u u u u u u stack full reset during normal operation 0000h 0--u uu11 u u u u u u 1 stack underflow reset during normal operation 0000h 0--u uu11 u u u u u 1 u mclr reset during sleep 0000h 0--u 10uu u 1 0 u u u u wdt reset 0000h 0--u 01uu 1 0 1 u u u u wdt wake-up pc + 2 u--u 00uu u 0 0 u u u u brown-out reset 0000h 0--1 11u0 1 1 1 1 0 u u interrupt wake-up from sleep pc + 2 (1) u--u 00uu u 1 0 u u u u legend: u = unchanged, x = unknown, ? = unimplemented bit, read as ? 0 ? note 1: when the wake-up is due to an interrupt and the gieh or giel bits are set, the pc is loaded with the interrupt vector (0x000008h or 0x000018h).
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 32 ? 2004 microchip technology inc. table 3-3: initialization co nditions for all registers register applicable devices power-on reset, brown-out reset mclr resets wdt reset reset instruction stack resets wake-up via wdt or interrupt tosu pic18f6x20 pic18f8x20 ---0 0000 ---0 0000 ---0 uuuu (3) tosh pic18f6x20 pic18f8x20 0000 0000 0000 0000 uuuu uuuu (3) tosl pic18f6x20 pic18f8x20 0000 0000 0000 0000 uuuu uuuu (3) stkptr pic18f6x20 pic18f8x20 00-0 0000 uu-0 0000 uu-u uuuu (3) pclatu pic18f6x20 pic18f8x20 ---0 0000 ---0 0000 ---u uuuu pclath pic18f6x20 pic18f8x20 0000 0000 0000 0000 uuuu uuuu pcl pic18f6x20 pic18f8x20 0000 0000 0000 0000 pc + 2 (2) tblptru pic18f6x20 pic18f8x20 --00 0000 --00 0000 --uu uuuu tblptrh pic18f6x20 pic18f8x20 0000 0000 0000 0000 uuuu uuuu tblptrl pic18f6x20 pic18f8x20 0000 0000 0000 0000 uuuu uuuu tablat pic18f6x20 pic18f8x20 0000 0000 0000 0000 uuuu uuuu prodh pic18f6x20 pic18f8x20 xxxx xxxx uuuu uuuu uuuu uuuu prodl pic18f6x20 pic18f8x20 xxxx xxxx uuuu uuuu uuuu uuuu intcon pic18f6x20 pic18f8x20 0000 000x 0000 000u uuuu uuuu (1) intcon2 pic18f6x20 pic18f8x20 1111 1111 1111 1111 uuuu uuuu (1) intcon3 pic18f6x20 pic18f8x20 1100 0000 1100 0000 uuuu uuuu (1) indf0 pic18f6x20 pic18f8x20 n/a n/a n/a postinc0 pic18f6x20 pic18f8x20 n/a n/a n/a postdec0 pic18f6x20 pic18f8x20 n/a n/a n/a preinc0 pic18f6x20 pic18f8x20 n/a n/a n/a plusw0 pic18f6x20 pic18f8x20 n/a n/a n/a fsr0h pic18f6x20 pic18f8x20 ---- xxxx ---- uuuu ---- uuuu fsr0l pic18f6x20 pic18f8x20 xxxx xxxx uuuu uuuu uuuu uuuu wreg pic18f6x20 pic18f8x20 xxxx xxxx uuuu uuuu uuuu uuuu indf1 pic18f6x20 pic18f8x20 n/a n/a n/a postinc1 pic18f6x20 pic18f8x20 n/a n/a n/a postdec1 pic18f6x20 pic18f8x20 n/a n/a n/a preinc1 pic18f6x20 pic18f8x20 n/a n/a n/a plusw1 pic18f6x20 pic18f8x20 n/a n/a n/a legend: u = unchanged, x = unknown, - = unimplemented bit, read as ? 0 ?, q = value depends on condition. shaded cells indicate conditions do not apply for the designated device. note 1: one or more bits in the intconx or pirx registers will be affected (to cause wake-up). 2: when the wake-up is due to an interrupt and the giel or gieh bit is set, the pc is loaded with the interrupt vector (0008h or 0018h). 3: when the wake-up is due to an interrupt and the giel or gieh bit is set, the tosu, tosh and tosl are updated with the current value of the pc. the stkptr is modified to point to the next location in the hardware stack. 4: see table 3-2 for reset value for specific condition. 5: bit 6 of porta, lata and trisa are enabled in ecio and rcio oscillator modes only. in all other oscillator modes, they are disabled and read ? 0 ?. 6: bit 6 of porta, lata and trisa are not available on all devices. when unimplemented, they are read ? 0 ?.
? 2004 microchip technology inc. ds39609b-page 33 pic18f6520/8520/6620/8620/6720/8720 fsr1h pic18f6x20 pic18f8x20 ---- xxxx ---- uuuu ---- uuuu fsr1l pic18f6x20 pic18f8x20 xxxx xxxx uuuu uuuu uuuu uuuu bsr pic18f6x20 pic18f8x20 ---- 0000 ---- 0000 ---- uuuu indf2 pic18f6x20 pic18f8x20 n/a n/a n/a postinc2 pic18f6x20 pic18f8x20 n/a n/a n/a postdec2 pic18f6x20 pic18f8x20 n/a n/a n/a preinc2 pic18f6x20 pic18f8x20 n/a n/a n/a plusw2 pic18f6x20 pic18f8x20 n/a n/a n/a fsr2h pic18f6x20 pic18f8x20 ---- xxxx ---- uuuu ---- uuuu fsr2l pic18f6x20 pic18f8x20 xxxx xxxx uuuu uuuu uuuu uuuu status pic18f6x20 pic18f8x20 ---x xxxx ---u uuuu ---u uuuu tmr0h pic18f6x20 pic18f8x20 0000 0000 uuuu uuuu uuuu uuuu tmr0l pic18f6x20 pic18f8x20 xxxx xxxx uuuu uuuu uuuu uuuu t0con pic18f6x20 pic18f8x20 1111 1111 1111 1111 uuuu uuuu osccon pic18f6x20 pic18f8x20 ---- ---0 ---- ---0 ---- ---u lvdcon pic18f6x20 pic18f8x20 --00 0101 --00 0101 --uu uuuu wdtcon pic18f6x20 pic18f8x20 ---- ---0 ---- ---0 ---- ---u rcon (4) pic18f6x20 pic18f8x20 0--q 11qq 0--q qquu u--u qquu tmr1h pic18f6x20 pic18f8x20 xxxx xxxx uuuu uuuu uuuu uuuu tmr1l pic18f6x20 pic18f8x20 xxxx xxxx uuuu uuuu uuuu uuuu t1con pic18f6x20 pic18f8x20 0-00 0000 u-uu uuuu u-uu uuuu tmr2 pic18f6x20 pic18f8x20 0000 0000 0000 0000 uuuu uuuu pr2 pic18f6x20 pic18f8x20 1111 1111 1111 1111 1111 1111 t2con pic18f6x20 pic18f8x20 -000 0000 -000 0000 -uuu uuuu sspbuf pic18f6x20 pic18f8x20 xxxx xxxx uuuu uuuu uuuu uuuu sspadd pic18f6x20 pic18f8x20 0000 0000 0000 0000 uuuu uuuu sspstat pic18f6x20 pic18f8x20 0000 0000 0000 0000 uuuu uuuu sspcon1 pic18f6x20 pic18f8x20 0000 0000 0000 0000 uuuu uuuu sspcon2 pic18f6x20 pic18f8x20 0000 0000 0000 0000 uuuu uuuu table 3-3: initialization conditions for all registers (continued) register applicable devices power-on reset, brown-out reset mclr resets wdt reset reset instruction stack resets wake-up via wdt or interrupt legend: u = unchanged, x = unknown, - = unimplemented bit, read as ? 0 ?, q = value depends on condition. shaded cells indicate conditions do not apply for the designated device. note 1: one or more bits in the intconx or pirx registers will be affected (to cause wake-up). 2: when the wake-up is due to an interrupt and the giel or gieh bit is set, the pc is loaded with the interrupt vector (0008h or 0018h). 3: when the wake-up is due to an interrupt and the giel or gieh bit is set, the tosu, tosh and tosl are updated with the current value of the pc. the stkptr is modified to point to the next location in the hardware stack. 4: see table 3-2 for reset value for specific condition. 5: bit 6 of porta, lata and trisa are enabled in ecio and rcio oscillator modes only. in all other oscillator modes, they are disabled and read ? 0 ?. 6: bit 6 of porta, lata and trisa are not available on all devices. when unimplemented, they are read ? 0 ?.
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 34 ? 2004 microchip technology inc. adresh pic18f6x20 pic18f8x20 xxxx xxxx uuuu uuuu uuuu uuuu adresl pic18f6x20 pic18f8x20 xxxx xxxx uuuu uuuu uuuu uuuu adcon0 pic18f6x20 pic18f8x20 --00 0000 --00 0000 --uu uuuu adcon1 pic18f6x20 pic18f8x20 --00 0000 --00 0000 --uu uuuu adcon2 pic18f6x20 pic18f8x20 0--- -000 0--- -000 u--- -uuu ccpr1h pic18f6x20 pic18f8x20 xxxx xxxx uuuu uuuu uuuu uuuu ccpr1l pic18f6x20 pic18f8x20 xxxx xxxx uuuu uuuu uuuu uuuu ccp1con pic18f6x20 pic18f8x20 --00 0000 --00 0000 --uu uuuu ccpr2h pic18f6x20 pic18f8x20 xxxx xxxx uuuu uuuu uuuu uuuu ccpr2l pic18f6x20 pic18f8x20 xxxx xxxx uuuu uuuu uuuu uuuu ccp2con pic18f6x20 pic18f8x20 --00 0000 --00 0000 --uu uuuu ccpr3h pic18f6x20 pic18f8x20 xxxx xxxx uuuu uuuu uuuu uuuu ccpr3l pic18f6x20 pic18f8x20 xxxx xxxx uuuu uuuu uuuu uuuu ccp3con pic18f6x20 pic18f8x20 0000 0000 0000 0000 uuuu uuuu cvrcon pic18f6x20 pic18f8x20 0000 0000 0000 0000 uuuu uuuu cmcon pic18f6x20 pic18f8x20 0000 0000 0000 0000 uuuu uuuu tmr3h pic18f6x20 pic18f8x20 xxxx xxxx uuuu uuuu uuuu uuuu tmr3l pic18f6x20 pic18f8x20 xxxx xxxx uuuu uuuu uuuu uuuu t3con pic18f6x20 pic18f8x20 0000 0000 uuuu uuuu uuuu uuuu pspcon pic18f6x20 pic18f8x20 0000 ---- 0000 ---- uuuu ---- spbrg1 pic18f6x20 pic18f8x20 0000 0000 0000 0000 uuuu uuuu rcreg1 pic18f6x20 pic18f8x20 0000 0000 0000 0000 uuuu uuuu txreg1 pic18f6x20 pic18f8x20 0000 0000 0000 0000 uuuu uuuu txsta1 pic18f6x20 pic18f8x20 0000 -010 0000 -010 uuuu -uuu rcsta1 pic18f6x20 pic18f8x20 0000 000x 0000 000x uuuu uuuu eeadrh pic18f6x20 pic18f8x20 ---- --00 ---- --00 ---- --uu eeadr pic18f6x20 pic18f8x20 0000 0000 0000 0000 uuuu uuuu eedata pic18f6x20 pic18f8x20 0000 0000 0000 0000 uuuu uuuu eecon2 pic18f6x20 pic18f8x20 ---- ---- ---- ---- ---- ---- eecon1 pic18f6x20 pic18f8x20 xx-0 x000 uu-0 u000 uu-0 u000 table 3-3: initialization conditi ons for all registers (continued) register applicable devices power-on reset, brown-out reset mclr resets wdt reset reset instruction stack resets wake-up via wdt or interrupt legend: u = unchanged, x = unknown, - = unimplemented bit, read as ? 0 ?, q = value depends on condition. shaded cells indicate conditions do not apply for the designated device. note 1: one or more bits in the intconx or pirx registers will be affected (to cause wake-up). 2: when the wake-up is due to an interrupt and the giel or gieh bit is set, the pc is loaded with the interrupt vector (0008h or 0018h). 3: when the wake-up is due to an interrupt and the giel or gieh bit is set, the tosu, tosh and tosl are updated with the current value of the pc. the stkptr is modified to point to the next location in the hardware stack. 4: see table 3-2 for reset value for specific condition. 5: bit 6 of porta, lata and trisa are enabled in ecio and rcio oscillator modes only. in all other oscillator modes, they are disabled and read ? 0 ?. 6: bit 6 of porta, lata and trisa are not available on all devices. when unimplemented, they are read ? 0 ?.
? 2004 microchip technology inc. ds39609b-page 35 pic18f6520/8520/6620/8620/6720/8720 ipr3 pic18f6x20 pic18f8x20 --11 1111 --11 1111 --uu uuuu pir3 pic18f6x20 pic18f8x20 --00 0000 --00 0000 --uu uuuu pie3 pic18f6x20 pic18f8x20 --00 0000 --00 0000 --uu uuuu ipr2 pic18f6x20 pic18f8x20 -1-1 1111 -1-1 1111 -u-u uuuu pir2 pic18f6x20 pic18f8x20 -0-0 0000 -0-0 0000 -u-u uuuu (1) pie2 pic18f6x20 pic18f8x20 -0-0 0000 -0-0 0000 -u-u uuuu ipr1 pic18f6x20 pic18f8x20 0111 1111 0111 1111 uuuu uuuu pir1 pic18f6x20 pic18f8x20 0000 0000 0000 0000 uuuu uuuu (1) pie1 pic18f6x20 pic18f8x20 0000 0000 0000 0000 uuuu uuuu memcon pic18f6x20 pic18f8x20 0-00 --00 0-00 --00 u-uu --uu trisj pic18f6x20 pic18f8x20 1111 1111 1111 1111 uuuu uuuu trish pic18f6x20 pic18f8x20 1111 1111 1111 1111 uuuu uuuu trisg pic18f6x20 pic18f8x20 ---1 1111 ---1 1111 ---u uuuu trisf pic18f6x20 pic18f8x20 1111 1111 1111 1111 uuuu uuuu trise pic18f6x20 pic18f8x20 1111 1111 1111 1111 uuuu uuuu trisd pic18f6x20 pic18f8x20 1111 1111 1111 1111 uuuu uuuu trisc pic18f6x20 pic18f8x20 1111 1111 1111 1111 uuuu uuuu trisb pic18f6x20 pic18f8x20 1111 1111 1111 1111 uuuu uuuu trisa (5,6) pic18f6x20 pic18f8x20 -111 1111 (5) -111 1111 (5) -uuu uuuu (5) latj pic18f6x20 pic18f8x20 xxxx xxxx uuuu uuuu uuuu uuuu lath pic18f6x20 pic18f8x20 xxxx xxxx uuuu uuuu uuuu uuuu latg pic18f6x20 pic18f8x20 ---x xxxx ---u uuuu ---u uuuu latf pic18f6x20 pic18f8x20 xxxx xxxx uuuu uuuu uuuu uuuu late pic18f6x20 pic18f8x20 xxxx xxxx uuuu uuuu uuuu uuuu latd pic18f6x20 pic18f8x20 xxxx xxxx uuuu uuuu uuuu uuuu latc pic18f6x20 pic18f8x20 xxxx xxxx uuuu uuuu uuuu uuuu latb pic18f6x20 pic18f8x20 xxxx xxxx uuuu uuuu uuuu uuuu lata (5,6) pic18f6x20 pic18f8x20 -xxx xxxx (5) -uuu uuuu (5) -uuu uuuu (5) table 3-3: initialization conditions for all registers (continued) register applicable devices power-on reset, brown-out reset mclr resets wdt reset reset instruction stack resets wake-up via wdt or interrupt legend: u = unchanged, x = unknown, - = unimplemented bit, read as ? 0 ?, q = value depends on condition. shaded cells indicate conditions do not apply for the designated device. note 1: one or more bits in the intconx or pirx registers will be affected (to cause wake-up). 2: when the wake-up is due to an interrupt and the giel or gieh bit is set, the pc is loaded with the interrupt vector (0008h or 0018h). 3: when the wake-up is due to an interrupt and the giel or gieh bit is set, the tosu, tosh and tosl are updated with the current value of the pc. the stkptr is modified to point to the next location in the hardware stack. 4: see table 3-2 for reset value for specific condition. 5: bit 6 of porta, lata and trisa are enabled in ecio and rcio oscillator modes only. in all other oscillator modes, they are disabled and read ? 0 ?. 6: bit 6 of porta, lata and trisa are not available on all devices. when unimplemented, they are read ? 0 ?.
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 36 ? 2004 microchip technology inc. portj pic18f6x20 pic18f8x20 xxxx xxxx uuuu uuuu uuuu uuuu porth pic18f6x20 pic18f8x20 0000 xxxx 0000 uuuu uuuu uuuu portg pic18f6x20 pic18f8x20 ---x xxxx uuuu uuuu ---u uuuu portf pic18f6x20 pic18f8x20 x000 0000 u000 0000 u000 0000 porte pic18f6x20 pic18f8x20 xxxx xxxx uuuu uuuu uuuu uuuu portd pic18f6x20 pic18f8x20 xxxx xxxx uuuu uuuu uuuu uuuu portc pic18f6x20 pic18f8x20 xxxx xxxx uuuu uuuu uuuu uuuu portb pic18f6x20 pic18f8x20 xxxx xxxx uuuu uuuu uuuu uuuu porta (5,6) pic18f6x20 pic18f8x20 -x0x 0000 (5) -u0u 0000 (5) -uuu uuuu (5) tmr4 pic18f6x20 pic18f8x20 0000 0000 0000 0000 uuuu uuuu pr4 pic18f6x20 pic18f8x20 1111 1111 1111 1111 uuuu uuuu t4con pic18f6x20 pic18f8x20 -000 0000 -000 0000 -uuu uuuu ccpr4h pic18f6x20 pic18f8x20 xxxx xxxx uuuu uuuu uuuu uuuu ccpr4l pic18f6x20 pic18f8x20 xxxx xxxx uuuu uuuu uuuu uuuu ccp4con pic18f6x20 pic18f8x20 0000 0000 0000 0000 uuuu uuuu ccpr5h pic18f6x20 pic18f8x20 xxxx xxxx uuuu uuuu uuuu uuuu ccpr5l pic18f6x20 pic18f8x20 xxxx xxxx uuuu uuuu uuuu uuuu ccp5con pic18f6x20 pic18f8x20 0000 0000 0000 0000 uuuu uuuu spbrg2 pic18f6x20 pic18f8x20 0000 0000 0000 0000 uuuu uuuu rcreg2 pic18f6x20 pic18f8x20 0000 0000 0000 0000 uuuu uuuu txreg2 pic18f6x20 pic18f8x20 0000 0000 0000 0000 uuuu uuuu txsta2 pic18f6x20 pic18f8x20 0000 -010 0000 -010 uuuu -uuu rcsta2 pic18f6x20 pic18f8x20 0000 000x 0000 000x uuuu uuuu table 3-3: initialization conditi ons for all registers (continued) register applicable devices power-on reset, brown-out reset mclr resets wdt reset reset instruction stack resets wake-up via wdt or interrupt legend: u = unchanged, x = unknown, - = unimplemented bit, read as ? 0 ?, q = value depends on condition. shaded cells indicate conditions do not apply for the designated device. note 1: one or more bits in the intconx or pirx registers will be affected (to cause wake-up). 2: when the wake-up is due to an interrupt and the giel or gieh bit is set, the pc is loaded with the interrupt vector (0008h or 0018h). 3: when the wake-up is due to an interrupt and the giel or gieh bit is set, the tosu, tosh and tosl are updated with the current value of the pc. the stkptr is modified to point to the next location in the hardware stack. 4: see table 3-2 for reset value for specific condition. 5: bit 6 of porta, lata and trisa are enabled in ecio and rcio oscillator modes only. in all other oscillator modes, they are disabled and read ? 0 ?. 6: bit 6 of porta, lata and trisa are not available on all devices. when unimplemented, they are read ? 0 ?.
? 2004 microchip technology inc. ds39609b-page 37 pic18f6520/8520/6620/8620/6720/8720 figure 3-3: time-out sequence on power-up (mclr tied to v dd via 1 k ? resistor) figure 3-4: time-out sequence on power-up (mclr not tied to v dd ): case 1 figure 3-5: time-out sequence on power-up (mclr not tied to v dd ): case 2 t pwrt t ost v dd mclr internal por pwrt time-out ost time-out internal reset t pwrt t ost v dd mclr internal por pwrt time-out ost time-out internal reset v dd mclr internal por pwrt time-out ost time-out internal reset t pwrt t ost
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 38 ? 2004 microchip technology inc. figure 3-6: slow rise time (mclr tied to v dd via 1 k ? resistor) figure 3-7: time-out sequence on por w/pll enabled (mclr tied to v dd via 1 k ? resistor) v dd mclr internal por pwrt time-out ost time-out internal reset 0v 5v t pwrt t ost t pwrt t ost v dd mclr iinternal por pwrt time-out ost time-out internal reset pll time-out t pll note: t ost = 1024 clock cycles. t pll 2 ms max. first three stages of the pwrt timer.
? 2004 microchip technology inc. ds39609b-page 39 pic18f6520/8520/6620/8620/6720/8720 4.0 memory organization there are three memory blocks in pic18fxx20 devices. they are: program memory data ram data eeprom data and program memory use separate busses, which allows for concurrent access of these blocks. additional detailed information for flash program memory and data eeprom is provided in section 5.0 ?flash program memory? and section 7.0 ?data eeprom memory? , respectively. in addition to on-chip flash, the pic18f8x20 devices are also capable of accessing external program mem- ory through an external memory bus. depending on the selected operating mode (discussed in section 4.1.1 ?pic18f8x20 program memory modes? ), the con- trollers may access either internal or external program memory exclusively, or both internal and external mem- ory in selected blocks. additional information on the external memory interface is provided in section 6.0 ?external memory interface? . 4.1 program memory organization a 21-bit program counter is capable of addressing the 2-mbyte program memory space. accessing a location between the physically implemented memory and the 2-mbyte address will cause a read of all ? 0 ?s (a nop instruction). devices in the pic18fxx20 family can be divided into three groups, based on program memory size. the pic18fx520 devices (pic18f6520 and pic18f8520) have 32 kbytes of on-chip flash memory, equivalent to 16,384 single-word instructions. the pic18fx620 devices (pic18f6620 and pic18f8620) have 64 kbytes of on-chip flash memory, equivalent to 32,768 single-word instructions. finally, the pic18fx720 devices (pic18f6720 and pic18f8720) have 128 kbytes of on-chip flash memory, equivalent to 65,536 single-word instructions. for all devices, the reset vector address is at 0000h and the interrupt vector addresses are at 0008h and 0018h. the program memory maps for all of the pic18fxx20 devices are compared in figure 4-1. 4.1.1 pic18f8x20 program memory modes pic18f8x20 devices differ significantly from their pic18 predecessors in their utilization of program memory. in addition to available on-chip flash program memory, these controllers can also address up to 2 mbytes of external program memory through the external memory interface. there are four distinct operating modes available to the controllers: microprocessor (mp) microprocessor with boot block (mpbb) extended microcontroller (emc) microcontroller (mc) the program memory mode is determined by setting the two least significant bits of the config3l config- uration byte, as shown in register 4-1. (see also section 23.1 ?configuration bits? for additional details on the device configuration bits.) the program memory modes operate as follows: the microprocessor mode permits access only to external program memory; the contents of the on-chip flash memory are ignored. the 21-bit program counter permits access to a 2-mbyte linear program memory space. the microprocessor with boot block mode accesses on-chip flash memory from addresses 000000h to 0007ffh for pic18f8520 devices and from 000000h to 0001ffh for pic18f8620 and pic18f8720 devices. above this, external program memory is accessed all the way up to the 2-mbyte limit. program execution automati- cally switches between the two memories, as required. the microcontroller mode accesses only on- chip flash memory. attempts to read above the physical limit of the on-chip flash (7fffh for the pic18f8520, 0ffffh for the pic18f8620, 1ffffh for the pic18f8720) causes a read of all ? 0 ?s (a nop instruction). the microcontroller mode is also the only operating mode available to pic18f6x20 devices. the extended microcontroller mode allows access to both internal and external program memories as a single block. the device can access its entire on-chip flash memory; above this, the device accesses external program memory up to the 2-mbyte program space limit. as with boot block mode, execution automatically switches between the two memories, as required. in all modes, the microcontroller has complete access to data ram and eeprom. figure 4-2 compares the memory maps of the different program memory modes. the differences between on- chip and external memory access limitations are more fully explained in table 4-1.
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 40 ? 2004 microchip technology inc. figure 4-1: internal program memory map and stack for pic18fxx20 devices table 4-1: memory access for pic18f 8x20 program memory modes pc<20:0> stack level 1 ? stack level 31 reset vector low priority ? ? call,rcall,return retfie,retlw 21 on-chip flash program memory high priority user memory space 1fffffh 010000h 00ffffh 200000h on-chip flash program memory on-chip flash program memory read ? 0 ? read ? 0 ? read ? 0 ? 008000h 007fffh 020000h 01ffffh 000000h 000018h 000008h 1fffffh 200000h 1fffffh 200000h pic18fx520 pic18fx620 pic18fx720 interrupt vector interrupt vector 000000h 000018h 000008h 000000h 000018h 000008h note: size of memory regions not to scale. (32 kbyte) (64 kbyte) (128 kbyte) operating mode internal program memory external program memory execution from table read from table write to execution from table read from table write to microprocessor no access no access no access yes yes yes microprocessor with boot block ye s yes yes yes yes yes microcontroller yes yes yes no access no access no access extended microcontroller ye s yes yes yes yes yes
? 2004 microchip technology inc. ds39609b-page 41 pic18f6520/8520/6620/8620/6720/8720 register 4-1: config3l configuration byte figure 4-2: memory maps for pic18f8x20 program memory modes r/p-1 u-0 u-0 u-0 u-0 u-0 r/p-1 r/p-1 wait ? ? ? ? ?pm1pm0 bit 7 bit 0 bit 7 wait: external bus data wait enable bit 1 = wait selections unavailable, device will not wait 0 = wait programmed by wait1 and wait0 bits of memcom register (memcom<5:4>) bit 6-2 unimplemented: read as ? 0 ? bit 1-0 pm1:pm0: processor data memory mode select bits 11 = microcontroller mode 10 = microprocessor mode 01 = microcontroller with boot block mode 00 = extended microcontroller mode legend: r = readable bit p = programmable bit u = unimplemented bit, read as ?0? - n = value after erase ?1? = bit is set ?0? = bit is cleared x = bit is unknown microprocessor mode (mp) 000000h 1fffffh external program memory external program memory 1fffffh 000000h on-chip program memory extended microcontroller mode (emc) microcontroller mode (mc) 000000h external on-chip program space execution on-chip program memory 1fffffh reads boot+1 1fffffh boot microprocessor with boot block mode (mpbb) 000000h on-chip program memory external program memory memory flash on-chip program memory (no access) ? 0 ?s external on-chip memory flash on-chip flash external on-chip memory flash boundary values for microprocessor with boot block, microcontroller and extended microcontroller modes (1) note 1: pic18f6x20 devices are included here for completeness, to show the boundaries of their boot blocks and program memory spaces. device boot boot+1 boundary boundary+1 available memory mode(s) pic18f6520 0007ffh 000800h 007fffh 008000h mc pic18f6620 0001ffh 000200h 00ffffh 010000h mc pic18f6720 0001ffh 000200h 01ffffh 020000h mc pic18f8520 0007ffh 000800h 007fffh 008000h mp, mpbb, mc, emc pic18f8620 0001ffh 000200h 00ffffh 010000h mp, mpbb, mc, emc pic18f8720 0001ffh 000200h 01ffffh 020000h mp, mpbb, mc, emc boundary boundary+1 boundary boundary+1
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 42 ? 2004 microchip technology inc. 4.2 return address stack the return address stack allows any combination of up to 31 program calls and interrupts to occur. the pc (program counter) is pushed onto the stack when a call or rcall instruction is executed, or an interrupt is acknowledged. the pc value is pulled off the stack on a return , retlw or a retfie instruction. pclatu and pclath are not affected by any of the return or call instructions. the stack operates as a 31-word by 21-bit ram and a 5-bit stack pointer, with the stack pointer initialized to 00000b after all resets. there is no ram associated with stack pointer 00000b. this is only a reset value. during a call type instruction, causing a push onto the stack, the stack pointer is first incremented and the ram location pointed to by the stack pointer is written with the contents of the pc. during a return type instruction, causing a pop from the stack, the contents of the ram location pointed to by the stkptr are transferred to the pc and then the stack pointer is decremented. the stack space is not part of either program or data space. the stack pointer is readable and writable and the address on the top of the stack is readable and writ- able through sfr registers. data can also be pushed to, or popped from the stack using the top-of-stack sfrs. status bits indicate if the stack pointer is at, or beyond the 31 levels provided. 4.2.1 top-of-stack access the top of the stack is readable and writable. three register locations, tosu, tosh and tosl, hold the contents of the stack location pointed to by the stkptr register. this allows users to implement a software stack if necessary. after a call , rcall or interrupt, the software can read the pushed value by reading the tosu, tosh and tosl registers. these values can be placed on a user defined software stack. at return time, the software can replace the tosu, tosh and tosl and do a return. the user must disable the global interrupt enable bits during this time to prevent inadvertent stack operations. 4.2.2 return stack pointer (stkptr) the stkptr register contains the stack pointer value, the stkful (stack full) status bit and the stkunf (stack underflow) status bits. register 4-2 shows the stkptr register. the value of the stack pointer can be 0 through 31. the stack pointer increments when val- ues are pushed onto the stack and decrements when values are popped off the stack. at reset, the stack pointer value will be ? 0 ?. the user may read and write the stack pointer value. this feature can be used by a real-time operating system for return stack maintenance. after the pc is pushed onto the stack 31 times (without popping any values off the stack), the stkful bit is set. the stkful bit can only be cleared in software or by a por. the action that takes place when the stack becomes full, depends on the state of the stvren (stack over- flow reset enable) configuration bit. refer to section 24.0 ?instruction set summary? for a description of the device configuration bits. if stvren is set (default), the 31st push will push the (pc + 2) value onto the stack, set the stkful bit and reset the device. the stkful bit will remain set and the stack pointer will be set to ? 0 ?. if stvren is cleared, the stkful bit will be set on the 31st push and the stack pointer will increment to 31. any additional pushes will not overwrite the 31st push and stkptr will remain at 31. when the stack has been popped enough times to unload the stack, the next pop will return a value of zero to the pc and sets the stkunf bit, while the stack pointer remains at ? 0 ?. the stkunf bit will remain set until cleared in software or a por occurs. note: returning a value of zero to the pc on an underflow has the effect of vectoring the program to the reset vector, where the stack conditions can be verified and appropriate actions can be taken.
? 2004 microchip technology inc. ds39609b-page 43 pic18f6520/8520/6620/8620/6720/8720 register 4-2: stkptr register figure 4-3: return address stack and associated registers 4.2.3 push and pop instructions since the top-of-stack (tos) is readable and writable, the ability to push values onto the stack and pull values off the stack, without disturbing normal program execution, is a desirable option. to push the current pc value onto the stack, a push instruction can be executed. this will increment the stack pointer and load the current pc value onto the stack. tosu, tosh and tosl can then be modified to place a return address on the stack. the ability to pull the tos value off of the stack and replace it with the value that was previously pushed onto the stack, without disturbing normal execution, is achieved by using the pop instruction. the pop instruction discards the current tos by decrementing the stack pointer. the previous value pushed onto the stack then becomes the tos value. 4.2.4 stack full/underflow resets these resets are enabled by programming the stvren configuration bit. when the stvren bit is disabled, a full or underflow condition will set the appropriate stkful or stkunf bit, but not cause a device reset. when the stvren bit is enabled, a full or underflow condition will set the appropriate stkful or stkunf bit and then cause a device reset. the stkful or stkunf bits are only cleared by the user software or a por reset. r/c-0 r/c-0 u-0 r/w-0 r/w-0 r/w-0 r/w-0 r/w-0 stkful (1) stkunf (1) ? sp4 sp3 sp2 sp1 sp0 bit 7 bit 0 bit 7 stkful: stack full flag bit 1 = stack became full or overflowed 0 = stack has not become full or overflowed bit 6 stkunf: stack underflow flag bit 1 = stack underflow occurred 0 = stack underflow did not occur bit 5 unimplemented: read as ? 0 ? bit 4-0 sp4:sp0: stack pointer location bits note 1: bit 7 and bit 6 can only be cleared in user software or by a por. legend: r = readable bit w = writable bit u = unimplemented bit, read as ?0? - n = value at por ?1? = bit is set ?0? = bit is cleared x = bit is unknown 00011 0x001a34 11111 11110 11101 00010 00001 00000 00010 return address stack top-of-stack 0x000d58 tosl tosh tosu 0x34 0x1a 0x00 stkptr<4:0>
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 44 ? 2004 microchip technology inc. 4.3 fast register stack a ?fast interrupt return? option is available for interrupts. a fast register stack is provided for the status, wreg and bsr registers and is only one in depth. the stack is not readable or writable and is loaded with the current value of the corresponding register when the processor vectors for an interrupt. the values in the registers are then loaded back into the working regis- ters, if the fast return instruction is used to return from the interrupt. a low or high priority interrupt source will push values into the stack registers. if both low and high priority interrupts are enabled, the stack registers cannot be used reliably for low priority interrupts. if a high priority interrupt occurs while servicing a low priority interrupt, the stack register values stored by the low priority interrupt will be overwritten. if high priority interrupts are not disabled during low priority interrupts, users must save the key registers in software during a low priority interrupt. if no interrupts are used, the fast register stack can be used to restore the status, wreg and bsr registers at the end of a subroutine call. to use the fast register stack for a subroutine call, a fast call instruction must be executed. example 4-1 shows a source code example that uses the fast register stack. example 4-1: fast register stack code example 4.4 pcl, pclath and pclatu the program counter (pc) specifies the address of the instruction to fetch for execution. the pc is 21 bits wide. the low byte is called the pcl register; this reg- ister is readable and writable. the high byte is called the pch register. this register contains the pc<15:8> bits and is not directly readable or writable; updates to the pch register may be performed through the pclath register. the upper byte is called pcu. this register contains the pc<20:16> bits and is not directly readable or writable; updates to the pcu register may be performed through the pclatu register. the pc addresses bytes in the program memory. to prevent the pc from becoming misaligned with word instructions, the lsb of the pcl is fixed to a value of ? 0 ?. the pc increments by 2 to address sequential instructions in the program memory. the call , rcall , goto and program branch instructions write to the program counter directly. for these instructions, the contents of pclath and pclatu are not transferred to the program counter. the contents of pclath and pclatu will be trans- ferred to the program counter by an operation that writes pcl. similarly, the upper two bytes of the program counter will be transferred to pclath and pclatu by an operation that reads pcl. this is useful for computed offsets to the pc (see section 4.8.1 ?computed goto? ). 4.5 clocking scheme/instruction cycle the clock input (from osc1) is internally divided by four to generate four non-overlapping quadrature clocks, namely q1, q2, q3 and q4. internally, the program counter (pc) is incremented every q1, the instruction is fetched from the program memory and latched into the instruction register in q4. the instruc- tion is decoded and executed during the following q1 through q4. the clocks and instruction execution flow are shown in figure 4-4. figure 4-4: clock/ instruction cycle call sub1, fast ;status, wreg, bsr ;saved in fast register ;stack ? ? sub1 ? ? ? return fast ;restore values saved ;in fast register stack q1 q2 q3 q4 q1 q2 q3 q4 q1 q2 q3 q4 osc1 q1 q2 q3 q4 pc osc2/clko (rc mode) pc pc+2 pc+4 fetch inst (pc) execute inst (pc-2) fetch inst (pc+2) execute inst (pc) fetch inst (pc+4) execute inst (pc+2) internal phase clock
? 2004 microchip technology inc. ds39609b-page 45 pic18f6520/8520/6620/8620/6720/8720 4.6 instruction flow/pipelining an ?instruction cycle? consists of four q cycles (q1, q2, q3 and q4). the instruction fetch and execute are pipelined, such that fetch takes one instruction cycle, while decode and execute takes another instruction cycle. however, due to the pipelining, each instruction effectively executes in one cycle. if an instruction causes the program counter to change (e.g., goto ), then two cycles are required to complete the instruction (example 4-2). a fetch cycle begins with the program counter (pc) incrementing in q1. in the execution cycle, the fetched instruction is latched into the ?instruction register? (ir) in cycle q1. this instruction is then decoded and executed during the q2, q3 and q4 cycles. data memory is read during q2 (operand read) and written during q4 (destination write). example 4-2: instruction pipeline flow 4.7 instructions in program memory the program memory is addressed in bytes. instruc- tions are stored as two bytes or four bytes in program memory. the least significant byte of an instruction word is always stored in a program memory location with an even address (lsb = 0 ). figure 4-5 shows an example of how instruction words are stored in the pro- gram memory. to maintain alignment with instruction boundaries, the pc increments in steps of 2 and the lsb will always read ? 0 ? (see section 4.4 ?pcl, pclath and pclatu? ). the call and goto instructions have an absolute program memory address embedded into the instruction. since instructions are always stored on word boundaries, the data contained in the instruction is a word address. the word address is written to pc<20:1>, which accesses the desired byte address in program memory. instruction #2 in figure 4-5 shows how the instruction ? goto 000006h ? is encoded in the program memory. program branch instructions, which encode a relative address offset, operate in the same manner. the offset value stored in a branch instruction represents the number of single-word instructions that the pc will be offset by. section 24.0 ?instruction set summary? provides further details of the instruction set. figure 4-5: instructions in program memory all instructions are single cycle, except for any program branches . these take two cycles since the fetch instruction is ?flush ed? from the pipeline, while the new instruction is being fetched and then executed. t cy 0t cy 1t cy 2t cy 3t cy 4t cy 5 1. movlw 55h fetch 1 execute 1 2. movwf portb fetch 2 execute 2 3. bra sub_1 fetch 3 execute 3 4. bsf porta, bit3 (forced nop) fetch 4 flush ( nop ) 5. instruction @ address sub_1 fetch sub_1 execute sub_1 word address lsb = 1 lsb = 0 program memory byte locations 000000h 000002h 000004h 000006h instruction 1: movlw 055h 0fh 55h 000008h instruction 2: goto 000006h efh 03h 00000ah f0h 00h 00000ch instruction 3: movff 123h, 456h c1h 23h 00000eh f4h 56h 000010h 000012h 000014h
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 46 ? 2004 microchip technology inc. 4.7.1 two-word instructions the pic18fxx20 devices have four two-word instruc- tions: movff , call , goto and lfsr . the second word of these instructions has the 4 msbs set to ? 1 ?s and is a special kind of nop instruction. the lower 12 bits of the second word contain data to be used by the instruc- tion. if the first word of the instruction is executed, the data in the second word is accessed. if the second word of the instruction is executed by itself (first word was skipped), it will execute as a nop . this action is necessary when the two-word instruction is preceded by a conditional instruction that changes the pc. a pro- gram example that demonstrates this concept is shown in example 4-3. refer to section 24.0 ?instruction set summary? for further details of the instruction set. example 4-3: two-word instructions 4.8 look-up tables look-up tables are implemented two ways. these are: computed goto table reads 4.8.1 computed goto a computed goto is accomplished by adding an offset to the program counter ( addwf pcl ). a look-up table can be formed with an addwf pcl instruction and a group of retlw 0xnn instructions. wreg is loaded with an offset into the table before executing a call to that table. the first instruction of the called routine is the addwf pcl instruction. the next instruction executed will be one of the retlw 0xnn instructions, that returns the value 0xnn to the calling function. the offset value (value in wreg) specifies the number of bytes that the program counter should advance. in this method, only one data byte may be stored in each instruction location and room on the return address stack is required. 4.8.2 table reads/table writes a better method of storing data in program memory allows 2 bytes of data to be stored in each instruction location. look-up table data may be stored 2 bytes per program word by using table reads and writes. the table pointer (tblptr) specifies the byte address and the table latch (tablat) contains the data that is read from, or written to program memory. data is transferred to/from program memory, one byte at a time. a description of the table read/table write operation is shown in section 5.0 ?flash program memory? . case 1: object code source code 0110 0110 0000 0000 tstfsz reg1 ; is ram location 0? 1100 0001 0010 0011 movff reg1, reg2 ; no, execute 2-word instruction 1111 0100 0101 0110 ; 2nd operand holds address of reg2 0010 0100 0000 0000 addwf reg3 ; continue code case 2: object code source code 0110 0110 0000 0000 tstfsz reg1 ; is ram location 0? 1100 0001 0010 0011 movff reg1, reg2 ; yes 1111 0100 0101 0110 ; 2nd operand becomes nop 0010 0100 0000 0000 addwf reg3 ; continue code
? 2004 microchip technology inc. ds39609b-page 47 pic18f6520/8520/6620/8620/6720/8720 4.9 data memory organization the data memory is implemented as static ram. each register in the data memory has a 12-bit address, allowing up to 4096 bytes of data memory. the data memory map is in turn divided into 16 banks of 256 bytes each. the lower 4 bits of the bank select register (bsr<3:0>) select which bank will be accessed. the upper 4 bits of the bsr are not implemented. the data memory space contains both special func- tion registers (sfr) and general purpose registers (gpr). the sfrs are used for control and status of the controller and peripheral functions, while gprs are used for data storage and scratch pad operations in the user?s application. the sfrs start at the last location of bank 15 (0fffh) and extend downwards. any remain- ing space beyond the sfrs in the bank may be imple- mented as gprs. gprs start at the first location of bank 0 and grow upwards. any read of an unimplemented location will read as ? 0 ?s. pic18fx520 devices have 2048 bytes of data ram, extending from bank 0 to bank 7 (000h through 7ffh). pic18fx620 and pic18fx720 devices have 3840 bytes of data ram, extending from bank 0 to bank 14 (000h through effh). the organization of the data memory space for these devices is shown in figure 4-6 and figure 4-7. the entire data memory may be accessed directly or indirectly. direct addressing may require the use of the bsr register. indirect addressing requires the use of a file select register (fsrn) and a corresponding indi- rect file operand (indfn). each fsr holds a 12-bit address value that can be used to access any location in the data memory map without banking. the instruction set and architecture allow operations across all banks. this may be accomplished by indirect addressing, or by the use of the movff instruction. the movff instruction is a two-word/two-cycle instruction that moves a value from one register to another. to ensure that commonly used registers (sfrs and select gprs) can be accessed in a single cycle, regardless of the current bsr values, an access bank is implemented. a segment of bank 0 and a segment of bank 15 comprise the access ram. section 4.10 ?access bank? provides a detailed description of the access ram. 4.9.1 general purpose register file the register file can be accessed either directly or indi- rectly. indirect addressing operates using a file select register and corresponding indirect file operand. the operation of indirect addressing is shown in section 4.12 ?indirect addressing, indf and fsr registers? . enhanced mcu devices may have banked memory in the gpr area. gprs are not initialized by a power-on reset and are unchanged on all other resets. data ram is available for use as general purpose registers by all instructions. the top section of bank 15 (f60h to fffh) contains sfrs. all other banks of data memory contain gpr registers, starting with bank 0. 4.9.2 special function registers the special function registers (sfrs) are registers used by the cpu and peripheral modules for controlling the desired operation of the device. these registers are implemented as static ram. a list of these registers is given in table 4-2 and table 4-3. the sfrs can be classified into two sets: those asso- ciated with the ?core? function and those related to the peripheral functions. those registers related to the ?core? are described in this section, while those related to the operation of the peripheral features are described in the section of that peripheral feature. the sfrs are typically distributed among the peripherals whose functions they control. the unused sfr locations are unimplemented and read as ? 0 ?s. the addresses for the sfrs are listed in table 4-2.
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 48 ? 2004 microchip technology inc. figure 4-6: data memory map for pic18fx520 devices bank 0 bank 1 bank 6 bank 15 data memory map bsr<3:0> = 0000 = 0001 = 1110 = 1111 060h 05fh f60h fffh 00h 5fh 60h ffh access bank when a = 0 , the bsr is ignored and the access bank is used. the first 96 bytes are general purpose ram (from bank 0). the second 160 bytes are special function registers (from bank 15). when a = 1 , the bsr is used to specify the ram location that the instruction uses. bank 7 bank 2 f5fh f00h effh 7ffh 300h 2ffh 200h 1ffh 100h 0ffh 000h = 0011 = 0010 access ram ffh 00h ffh 00h ffh 00h ffh 00h ffh 00h gprs gprs gprs sfrs unused access ram high access ram low bank 3 to 6ffh 800h 700h = 0110 (sfrs) gprs unused, gprs ffh 00h bank 14 bank 8 to read as ? 0 ? = 0111 = 1000 ? ? ? ? ? ?
? 2004 microchip technology inc. ds39609b-page 49 pic18f6520/8520/6620/8620/6720/8720 figure 4-7: data memory map for pic18f x620 and pic18fx720 devices bank 0 bank 1 bank 13 bank 15 data memory map bsr<3:0> = 0000 = 0001 = 1110 = 1111 060h 05fh f60h fffh 00h 5fh 60h ffh access bank when a = 0 , the bsr is ignored and the access bank is used. the first 96 bytes are general purpose ram (from bank 0). the second 160 bytes are special function registers (from bank 15). when a = 1 , the bsr is used to specify the ram location that the instruction uses. bank 4 bank 3 bank 2 f5fh f00h effh 3ffh 300h 2ffh 200h 1ffh 100h 0ffh 000h = 0011 = 0010 access ram ffh 00h ffh 00h ffh 00h ffh 00h ffh 00h ffh 00h gprs gprs gprs gprs sfrs unused access ram high access ram low bank 14 gprs gprs bank 5 to 4ffh 400h dffh 500h e00h = 0100 (sfrs) gprs = 0101 = 1101 ? ? ?
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 50 ? 2004 microchip technology inc. table 4-2: special function register map address name address name address name address name fffh tosu fdfh indf2 (3) fbfh ccpr1h f9fh ipr1 ffeh tosh fdeh postinc2 (3) fbeh ccpr1l f9eh pir1 ffdh tosl fddh postdec2 (3) fbdh ccp1con f9dh pie1 ffch stkptr fdch preinc2 (3) fbch ccpr2h f9ch memcon (2) ffbh pclatu fdbh plusw2 (3) fbbh ccpr2l f9bh ? (1) ffah pclath fdah fsr2h fbah ccp2con f9ah trisj ff9h pcl fd9h fsr2l fb9h ccpr3h f99h trish ff8h tblptru fd8h status fb8h ccpr3l f98h trisg ff7h tblptrh fd7h tmr0h fb7h ccp3con f97h trisf ff6h tblptrl fd6h tmr0l fb6h ? (1) f96h trise ff5h tablat fd5h t0con fb5h cvrcon f95h trisd ff4h prodh fd4h ? (1) fb4h cmcon f94h trisc ff3h prodl fd3h osccon fb3h tmr3h f93h trisb ff2h intcon fd2h lvdcon fb2h tmr3l f92h trisa ff1h intcon2 fd1h wdtcon fb1h t3con f91h latj ff0h intcon3 fd0h rcon fb0h pspcon f90h lath fefh indf0 (3) fcfh tmr1h fafh spbrg1 f8fh latg feeh postinc0 (3) fceh tmr1l faeh rcreg1 f8eh latf fedh postdec0 (3) fcdh t1con fadh txreg1 f8dh late fech preinc0 (3) fcch tmr2 fach txsta1 f8ch latd febh plusw0 (3) fcbh pr2 fabh rcsta1 f8bh latc feah fsr0h fcah t2con faah eeadrh f8ah latb fe9h fsr0l fc9h sspbuf fa9h eeadr f89h lata fe8h wreg fc8h sspadd fa8h eedata f88h portj fe7h indf1 (3) fc7h sspstat fa7h eecon2 f87h porth fe6h postinc1 (3) fc6h sspcon1 fa6h eecon1 f86h portg fe5h postdec1 (3) fc5h sspcon2 fa5h ipr3 f85h portf fe4h preinc1 (3) fc4h adresh fa4h pir3 f84h porte fe3h plusw1 (3) fc3h adresl fa3h pie3 f83h portd fe2h fsr1h fc2h adcon0 fa2h ipr2 f82h portc fe1h fsr1l fc1h adcon1 fa1h pir2 f81h portb fe0h bsr fc0h adcon2 fa0h pie2 f80h porta note 1: unimplemented registers are read as ? 0 ?. 2: this register is unused on pic18f6x20 devices. always maintain this register clear. 3: this is not a physical register.
? 2004 microchip technology inc. ds39609b-page 51 pic18f6520/8520/6620/8620/6720/8720 address name address name address name address name f7fh ? (1) f5fh ? (1) f3fh ? (1) f1fh ? (1) f7eh ? (1) f5eh ? (1) f3eh ? (1) f1eh ? (1) f7dh ? (1) f5dh ? (1) f3dh ? (1) f1dh ? (1) f7ch ? (1) f5ch ? (1) f3ch ? (1) f1ch ? (1) f7bh ? (1) f5bh ? (1) f3bh ? (1) f1bh ? (1) f7ah ? (1) f5ah ? (1) f3ah ? (1) f1ah ? (1) f79h ? (1) f59h ? (1) f39h ? (1) f19h ? (1) f78h tmr4 f58h ? (1) f38h ? (1) f18h ? (1) f77h pr4 f57h ? (1) f37h ? (1) f17h ? (1) f76h t4con f56h ? (1) f36h ? (1) f16h ? (1) f75h ccpr4h f55h ? (1) f35h ? (1) f15h ? (1) f74h ccpr4l f54h ? (1) f34h ? (1) f14h ? (1) f73h ccp4con f53h ? (1) f33h ? (1) f13h ? (1) f72h ccpr5h f52h ? (1) f32h ? (1) f12h ? (1) f71h ccpr5l f51h ? (1) f31h ? (1) f11h ? (1) f70h ccp5con f50h ? (1) f30h ? (1) f10h ? (1) f6fh spbrg2 f4fh ? (1) f2fh ? (1) f0fh ? (1) f6eh rcreg2 f4eh ? (1) f2eh ? (1) f0eh ? (1) f6dh txreg2 f4dh ? (1) f2dh ? (1) f0dh ? (1) f6ch txsta2 f4ch ? (1) f2ch ? (1) f0ch ? (1) f6bh rcsta2 f4bh ? (1) f2bh ? (1) f0bh ? (1) f6ah ? (1) f4ah ? (1) f2ah ? (1) f0ah ? (1) f69h ? (1) f49h ? (1) f29h ? (1) f09h ? (1) f68h ? (1) f48h ? (1) f28h ? (1) f08h ? (1) f67h ? (1) f47h ? (1) f27h ? (1) f07h ? (1) f66h ? (1) f46h ? (1) f26h ? (1) f06h ? (1) f65h ? (1) f45h ? (1) f25h ? (1) f05h ? (1) f64h ? (1) f44h ? (1) f24h ? (1) f04h ? (1) f63h ? (1) f43h ? (1) f23h ? (1) f03h ? (1) f62h ? (1) f42h ? (1) f22h ? (1) f02h ? (1) f61h ? (1) f41h ? (1) f21h ? (1) f01h ? (1) f60h ? (1) f40h ? (1) f20h ? (1) f00h ? (1) note 1: unimplemented registers are read as ? 0 ?. 2: this register is not available on pic18f6x20 devices. 3: this is not a physical register. table 4-2: special function register map (continued)
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 52 ? 2004 microchip technology inc. table 4-3: register file summary file name bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 value on por, bor details on page: tosu ? ? ? top-of-stack upper byte (tos<20:16>) ---0 0000 32, 42 tosh top-of-stack high byte (tos<15:8>) 0000 0000 32, 42 tosl top-of-stack low byte (tos<7:0>) 0000 0000 32, 42 stkptr stkful stkunf ? return stack pointer 00-0 0000 32, 43 pclatu ? ? bit 21 holding register for pc<20:16> --10 0000 32, 44 pclath holding register for pc<15:8> 0000 0000 32, 44 pcl pc low byte (pc<7:0>) 0000 0000 32, 44 tblptru ? ?bit 21 (2) program memory table pointer upper byte (tblptr<20:16>) --00 0000 32, 64 tblptrh program memory table pointer high byte (tblptr<15:8>) 0000 0000 32, 64 tblptrl program memory table pointer low byte (tblptr<7:0>) 0000 0000 32, 64 tablat program memory table latch 0000 0000 32, 64 prodh product register high byte xxxx xxxx 32, 85 prodl product register low byte xxxx xxxx 32, 85 intcon gie/gieh peie/giel tmr0ie int0ie rbie tmr0if int0if rbif 0000 0000 32, 89 intcon2 rbpu intedg0 intedg1 intedg2 intedg3 tmr0ip int3ip rbip 1111 1111 32, 90 intcon3 int2ip int1ip int3ie int 2ie int1ie int3if int2if int1if 1100 0000 32, 91 indf0 uses contents of fsr0 to address data memory ? value of fsr0 not changed (not a physical register) n/a 57 postinc0 uses contents of fsr0 to address data memory ? value of fsr0 post-incremented (not a physical register) n/a 57 postdec0 uses contents of fsr0 to address data memory ? value of fsr0 post-decremented (not a physical register) n/a 57 preinc0 uses contents of fsr0 to address data memory ? value of fsr0 pre-incremented (not a physical register) n/a 57 plusw0 uses contents of fsr0 to address data memory ? value of fsr0 pre-incremented (not a physical register) ? value of fsr0 offset by value in wreg n/a 57 fsr0h ? ? ? ? indirect data memory address pointer 0 high byte ---- 0000 32, 57 fsr0l indirect data memory address pointer 0 low byte xxxx xxxx 32, 57 wreg working register xxxx xxxx 32 indf1 uses contents of fsr1 to address data memory ? value of fsr1 not changed (not a physical register) n/a 57 postinc1 uses contents of fsr1 to address data memory ? value of fsr1 post-incremented (not a physical register) n/a 57 postdec1 uses contents of fsr1 to address data memory ? value of fsr1 post-decremented (not a physical register) n/a 57 preinc1 uses contents of fsr1 to address data memory ? value of fsr1 pre-incremented (not a physical register) n/a 57 plusw1 uses contents of fsr1 to address data memory ? value of fsr1 pre-incremented (not a physical register) ? value of fsr1 offset by value in wreg n/a 57 fsr1h ? ? ? ? indirect data memory address pointer 1 high byte ---- 0000 33, 57 fsr1l indirect data memory address pointer 1 low byte xxxx xxxx 33, 57 bsr ? ? ? ? bank select register ---- 0000 33, 56 indf2 uses contents of fsr2 to address data memory ? value of fsr2 not changed (not a physical register) n/a 57 postinc2 uses contents of fsr2 to address data memory ? value of fsr2 post-incremented (not a physical register) n/a 57 postdec2 uses contents of fsr2 to address data memory ? value of fsr2 post-decremented (not a physical register) n/a 57 legend: x = unknown, u = unchanged, ? = unimplemented, q = value depends on condition note 1: ra6 and associated bits are configured as port pins in rcio and ecio oscillator modes only and read ? 0 ? in all other oscillator modes. 2: bit 21 of the tblptru allows access to the device configuration bits. 3: these registers are unused on pic18f6x20 devices; always maintain these clear.
? 2004 microchip technology inc. ds39609b-page 53 pic18f6520/8520/6620/8620/6720/8720 preinc2 uses contents of fsr2 to address data memory ? value of fsr2 pre-incremented (not a physical register) n/a 57 plusw2 uses contents of fsr2 to address data memory ? value of fsr2 pre-incremented (not a physical register) ? value of fsr2 offset by value in wreg n/a 57 fsr2h ? ? ? ? indirect data memory address pointer 2 high byte ---- 0000 33, 57 fsr2l indirect data memory address pointer 2 low byte xxxx xxxx 33, 57 status ? ? ?novzdcc ---x xxxx 33, 59 tmr0h timer0 register high byte 0000 0000 33, 133 tmr0l timer0 register low byte xxxx xxxx 33, 133 t0con tmr0on t08bit t0cs t0se psa t0ps2 t0ps1 t0ps0 1111 1111 33, 131 osccon ? ? ? ? ? ? ?scs ---- ---0 25, 33 lvdcon ? ? irvst lvden lvdl3 lvdl2 lvdl1 lvdl0 --00 0101 33, 235 wdtcon ? ? ? ? ? ? ?swdte ---- ---0 33, 250 rcon ipen ? ?ri to pd por bor 0--1 11qq 33, 60, 101 tmr1h timer1 register high byte xxxx xxxx 33, 135 tmr1l timer1 register low byte xxxx xxxx 33, 135 t1con rd16 ? t1ckps1 t1ckps0 t1oscen t1sync tmr1cs tmr1on 0-00 0000 33, 135 tmr2 timer2 register 0000 0000 33, 141 pr2 timer2 period register 1111 1111 33, 142 t2con ? t2outps3 t2outps2 t2outps1 t2outps0 tmr2on t2ckps1 t2ckps0 -000 0000 33, 141 sspbuf ssp receive buffer/transmit register xxxx xxxx 33, 157 sspadd ssp address register in i 2 c slave mode. ssp baud rate reload register in i 2 c master mode. 0000 0000 33, 166 sspstat smp cke d/a psr/w ua bf 0000 0000 33, 158 sspcon1 wcol sspov sspen ckp sspm3 sspm2 sspm1 sspm0 0000 0000 33, 168 sspcon2 gcen ackstat ackdt acken rcen pen rsen sen 0000 0000 33, 169 adresh a/d result register high byte xxxx xxxx 34, 215 adresl a/d result register low byte xxxx xxxx 34, 215 adcon0 ? ? chs3 chs2 chs1 chs0 go/done adon --00 0000 34, 213 adcon1 ? ? vcfg1 vcfg0 pcfg3 pcfg2 pcfg1 pcfg0 --00 0000 34, 214 adcon2 adfm ? ? ? ? adcs2 adcs1 adcs0 0--- -000 34, 215 ccpr1h capture/compare/pwm register 1 high byte xxxx xxxx 34, 151, 152 ccpr1l capture/compare/pwm register 1 low byte xxxx xxxx 34, 151, 152 ccp1con ? ? dc1b1 dc1b0 ccp1m3 ccp1m2 ccp1m1 ccp1m0 --00 0000 34, 149 ccpr2h capture/compare/pwm register 2 high byte xxxx xxxx 34, 151, 152 ccpr2l capture/compare/pwm register 2 low byte xxxx xxxx 34, 151, 152 ccp2con ? ? dc2b1 dc2b0 ccp2m3 ccp2m2 ccp2m1 ccp2m0 --00 0000 34, 149 table 4-3: register file summary (continued) file name bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 value on por, bor details on page: legend: x = unknown, u = unchanged, ? = unimplemented, q = value depends on condition note 1: ra6 and associated bits are configured as port pins in rcio and ecio oscillator modes only and read ? 0 ? in all other oscillator modes. 2: bit 21 of the tblptru allows access to the device configuration bits. 3: these registers are unused on pic18f6x20 devices; always maintain these clear.
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 54 ? 2004 microchip technology inc. ccpr3h capture/compare/pwm register 3 high byte xxxx xxxx 34, 151, 152 ccpr3l capture/compare/pwm register 3 low byte xxxx xxxx 34, 151, 152 ccp3con ? ? dc3b1 dc3b0 ccp3m3 ccp3m2 ccp3m1 ccp3m0 --00 0000 34, 149 cvrcon cvren cvroe cvrr cvrss cvr3 cvr2 cvr1 cvr0 0000 0000 34, 229 cmcon c2out c1out c2inv c1inv cis cm2 cm1 cm0 0000 0000 34, 223 tmr3h timer3 register high byte xxxx xxxx 34, 143 tmr3l timer3 register low byte xxxx xxxx 34, 143 t3con rd16 t3ccp2 t3ckps1 t3ckps0 t3ccp1 t3sync tmr3cs tmr3on 0000 0000 34, 143 pspcon ibf obf ibov pspmode ? ? ? ? 0000 ---- 34, 129 spbrg1 usart1 baud rate generator 0000 0000 34, 205 rcreg1 usart1 receive register 0000 0000 34, 206 txreg1 usart1 transmit register 0000 0000 34, 204 txsta1 csrc tx9 txen sync ?brghtrmttx9d 0000 -010 34, 198 rcsta1 spen rx9 sren cren adden ferr oerr rx9d 0000 000x 34, 199 eeadrh ? ? ? ? ? ? ee adr register high ---- --00 34, 79 eeadr data eeprom address register 0000 0000 34, 79 eedata data eeprom data register 0000 0000 34, 79 eecon2 data eeprom control register 2 (not a physical register) ---- ---- 34, 79 eecon1 eepgd cfgs ? free wrerr wren wr rd xx-0 x000 34, 80 ipr3 ? ? rc2ip tx2ip tmr4ip ccp5ip ccp4ip ccp3ip --11 1111 35, 100 pir3 ? ? rc2if tx2if tmr4if ccp5if ccp4if ccp3if --00 0000 35, 94 pie3 ? ? rc2ie tx2ie tmr4ie ccp5ie ccp4ie ccp3ie --00 0000 35, 97 ipr2 ?cmip ? eeip bclip lvdip tmr3ip ccp2ip -1-1 1111 35, 99 pir2 ?cmif ? eeif bclif lvdif tmr3if ccp2if -0-0 0000 35, 93 pie2 ?cmie ? eeie bclie lvdie tmr3ie ccp2ie -0-0 0000 35, 96 ipr1 pspip adip rcip txip sspip ccp1ip tmr2ip tmr1ip 0111 1111 35, 98 pir1 pspif adif rcif txif sspif ccp1if tmr2if tmr1if 0000 0000 35, 92 pie1 pspie adie rcie txie sspie ccp1ie tmr2ie tmr1ie 0000 0000 35, 95 memcon (3) ebdis ?wait1wait0 ? ?wm1wm0 0-00 --00 35, 71 trisj (3) data direction control register for portj 1111 1111 35, 125 trish (3) data direction control register for porth 1111 1111 35, 122 trisg ? ? ? data direction control register for portg ---1 1111 35, 120 trisf data direction control register for portf 1111 1111 35, 117 trise data direction control register for porte 1111 1111 35, 114 trisd data direction control register for portd 1111 1111 35, 111 trisc data direction control register for portc 1111 1111 35, 109 trisb data direction control register for portb 1111 1111 35, 106 trisa ? trisa6 (1) data direction control register for porta -111 1111 35, 103 table 4-3: register file summary (continued) file name bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 value on por, bor details on page: legend: x = unknown, u = unchanged, ? = unimplemented, q = value depends on condition note 1: ra6 and associated bits are configured as port pins in rcio and ecio oscillator modes only and read ? 0 ? in all other oscillator modes. 2: bit 21 of the tblptru allows access to the device configuration bits. 3: these registers are unused on pic18f6x20 devices; always maintain these clear.
? 2004 microchip technology inc. ds39609b-page 55 pic18f6520/8520/6620/8620/6720/8720 latj (3) read portj data latch, write portj data latch xxxx xxxx 35, 125 lath (3) read porth data latch, write porth data latch xxxx xxxx 35, 122 latg ? ? ? read portg data latch, write portg data latch ---x xxxx 35, 120 latf read portf data latch, write portf data latch xxxx xxxx 35, 117 late read porte data latch, write porte data latch xxxx xxxx 35, 114 latd read portd data latch, write portd data latch xxxx xxxx 35, 111 latc read portc data latch, write portc data latch xxxx xxxx 35, 109 latb read portb data latch, write portb data latch xxxx xxxx 35, 106 lata ?lata6 (1) read porta data latch, write porta data latch (1) -xxx xxxx 35, 103 portj (3) read portj pins, write portj data latch xxxx xxxx 36, 125 porth (3) read porth pins, write porth data latch xxxx xxxx 36, 122 portg ? ? ? read portg pins, write portg data latch ---x xxxx 36, 120 portf read portf pins, write portf data latch xxxx xxxx 36, 117 porte read porte pins, write porte data latch xxxx xxxx 36, 114 portd read portd pins, write portd data latch xxxx xxxx 36, 111 portc read portc pins, write portc data latch xxxx xxxx 36, 109 portb read portb pins, write portb data latch xxxx xxxx 36, 106 porta ?ra6 (1) read porta pins, write porta data latch (1) -x0x 0000 36, 103 tmr4 timer4 register 0000 0000 36, 148 pr4 timer4 period register 1111 1111 36, 148 t4con ? t4outps3 t4outps2 t4outps1 t4outps0 tmr4on t4ckps1 t4ckps0 -000 0000 36, 147 ccpr4h capture/compare/pwm register 4 high byte xxxx xxxx 36, 151, 152 ccpr4l capture/compare/pwm register 4 low byte xxxx xxxx 36, 151, 152 ccp4con ? ? dc4b1 dc4b0 ccp4m3 ccp4m2 ccp4m1 ccp4m0 0000 0000 36, 149 ccpr5h capture/compare/pwm register 5 high byte xxxx xxxx 36, 151, 152 ccpr5l capture/compare/pwm register 5 low byte xxxx xxxx 36, 151, 152 ccp5con ? ? dc5b1 dc5b0 ccp5m3 ccp5m2 ccp5m1 ccp5m0 0000 0000 36, 149 spbrg2 usart2 baud rate generator 0000 0000 36, 205 rcreg2 usart2 receive register 0000 0000 36, 206 txreg2 usart2 transmit register 0000 0000 36, 204 txsta2 csrc tx9 txen sync ?brghtrmttx9d 0000 -010 36, 198 rcsta2 spen rx9 sren cren adden ferr oerr rx9d 0000 000x 36, 199 table 4-3: register file summary (continued) file name bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 value on por, bor details on page: legend: x = unknown, u = unchanged, ? = unimplemented, q = value depends on condition note 1: ra6 and associated bits are configured as port pins in rcio and ecio oscillator modes only and read ? 0 ? in all other oscillator modes. 2: bit 21 of the tblptru allows access to the device configuration bits. 3: these registers are unused on pic18f6x20 devices; always maintain these clear.
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 56 ? 2004 microchip technology inc. 4.10 access bank the access bank is an architectural enhancement, which is very useful for c compiler code optimization. the techniques used by the c compiler may also be useful for programs written in assembly. this data memory region can be used for: intermediate computational values local variables of subroutines faster context saving/switching of variables common variables faster evaluation/control of sfrs (no banking) the access bank is comprised of the upper 160 bytes in bank 15 (sfrs) and the lower 96 bytes in bank 0. these two sections will be referred to as access ram high and access ram low, respectively. figure 4-7 indicates the access ram areas. a bit in the instruction word specifies if the operation is to occur in the bank specified by the bsr register or in the access bank. this bit is denoted by the ?a? bit (for access bit). when forced in the access bank (a = 0 ), the last address in access ram low is followed by the first address in access ram high. access ram high maps the special function registers, so that these registers can be accessed without any software overhead. this is useful for testing status flags and modifying control bits. 4.11 bank select register (bsr) the need for a large general purpose memory space dictates a ram banking scheme. the data memory is partitioned into sixteen banks. when using direct addressing, the bsr should be configured for the desired bank. bsr<3:0> holds the upper 4 bits of the 12-bit ram address. the bsr<7:4> bits will always read ? 0 ?s and writes will have no effect. a movlb instruction has been provided in the instruction set to assist in selecting banks. if the currently selected bank is not implemented, any read will return all ? 0 ?s and all writes are ignored. the status register bits will be set/cleared as appropriate for the instruction performed. each bank extends up to ffh (256 bytes). all data memory is implemented as static ram. a movff instruction ignores the bsr, since the 12-bit addresses are embedded into the instruction word. section 4.12 ?indirect addressing, indf and fsr registers? provides a description of indirect address- ing, which allows linear addressing of the entire ram space. figure 4-8: direct addressing note 1: for register file map detail, see table 4-2. 2: the access bit of the instruction can be used to force an override of the selected bank (bsr<3:0>) to the registers of the access bank. 3: the movff instruction embeds the entire 12-bit address in the instruction. data memory (1) direct addressing bank select (2) location select (3) bsr<3:0> 7 0 from opcode (3) 00h 01h 0eh 0fh bank 0 bank 1 bank 14 bank 15 1ffh 100h 0ffh 000h effh e00h fffh f00h
? 2004 microchip technology inc. ds39609b-page 57 pic18f6520/8520/6620/8620/6720/8720 4.12 indirect addressing, indf and fsr registers indirect addressing is a mode of addressing data mem- ory, where the data memory address in the instruction is not fixed. an fsr register is used as a pointer to the data memory location that is to be read or written. since this pointer is in ram, the contents can be modified by the program. this can be useful for data tables in the data memory and for software stacks. figure 4-9 shows the operation of indirect addressing. this shows the moving of the value to the data memory address, specified by the value of the fsr register. indirect addressing is possible by using one of the indf registers. any instruction using the indf register actually accesses the register pointed to by the file select register, fsr. reading the indf register itself, indirectly (fsr = 0 ), will read 00h. writing to the indf register indirectly, results in a no operation. the fsr register contains a 12-bit address, which is shown in figure 4-10. the indfn register is not a physical register. address- ing indfn actually addresses the register whose address is contained in the fsrn register (fsrn is a pointer). this is indirect addressing. example 4-4 shows a simple use of indirect addressing to clear the ram in bank 1 (locations 100h-1ffh) in a minimum number of instructions. example 4-4: how to clear ram (bank 1) using indirect addressing there are three indirect addressing registers. to address the entire data memory space (4096 bytes), these registers are 12 bits wide. to store the 12 bits of addressing information, two 8-bit registers are required. these indirect addressing registers are: 1. fsr0: composed of fsr0h:fsr0l 2. fsr1: composed of fsr1h:fsr1l 3. fsr2: composed of fsr2h:fsr2l in addition, there are registers indf0, indf1 and indf2, which are not physically implemented. reading or writing to these registers activates indirect address- ing, with the value in the corresponding fsr register being the address of the data. if an instruction writes a value to indf0, the value will be written to the address pointed to by fsr0h:fsr0l. a read from indf1 reads the data from the address pointed to by fsr1h:fsr1l. indfn can be used in code anywhere an operand can be used. if indf0, indf1 or indf2 are read indirectly via an fsr, all ? 0 ?s are read (zero bit is set). similarly, if indf0, indf1 or indf2 are written to indirectly, the operation will be equivalent to a nop instruction and the status bits are not affected. 4.12.1 indirect addressing operation each fsr register has an indf register associated with it, plus four additional register addresses. perform- ing an operation on one of these five registers determines how the fsr will be modified during indirect addressing. when data access is done to one of the five indfn locations, the address selected will configure the fsrn register to: do nothing to fsrn after an indirect access (no change) ? indfn. auto-decrement fsrn after an indirect access (post-decrement) ? postdecn. auto-increment fsrn after an indirect access (post-increment) ? postincn. auto-increment fsrn before an indirect access (pre-increment) ? preincn. use the value in the wreg register as an offset to fsrn. do not modify the value of the wreg or the fsrn register after an indirect access (no change) ? pluswn. when using the auto-increment or auto-decrement features, the effect on the fsr is not reflected in the status register. for example, if the indirect address causes the fsr to equal ? 0 ?, the z bit will not be set. incrementing or decrementing an fsr affects all 12 bits. that is, when fsrnl overflows from an increment, fsrnh will be incremented automatically. adding these features allows the fsrn to be used as a stack pointer, in addition to its uses for table operations in data memory. each fsr has an address associated with it that performs an indexed indirect access. when a data access to this indfn location (pluswn) occurs, the fsrn is configured to add the signed value in the wreg register and the value in fsr to form the address before an indirect access. the fsr value is not changed. if an fsr register contains a value that points to one of the indfn, an indirect read will read 00h (zero bit is set), while an indirect write will be equivalent to a nop (status bits are not affected). if an indirect addressing operation is done where the tar- get address is an fsrnh or fsrnl register, the write operation will dominate over the pre- or post-increment/ decrement functions. lfsr fsr0 ,0x100 ; next clrf postinc0 ; clear indf ; register and ; inc pointer btfss fsr0h, 1 ; all done with ; bank 1? goto next ; no, clear next continue ; yes, continue
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 58 ? 2004 microchip technology inc. figure 4-9: indirect addressing operation figure 4-10: indirect addressing opcode address file address = access of an indirect addressing register fsr instruction executed instruction fetched ram opcode file 12 12 12 bsr<3:0> 8 4 0h fffh note 1: for register file map detail, see table 4-2. data memory (1) indirect addressing fsr register 11 0 0fffh 0000h location select
? 2004 microchip technology inc. ds39609b-page 59 pic18f6520/8520/6620/8620/6720/8720 4.13 status register the status register, shown in register 4-3, contains the arithmetic status of the alu. the status register can be the destination for any instruction, as with any other reg- ister. if the status register is the destination for an instruction that affects the z, dc, c, ov or n bits, then the write to these five bits is disabled. these bits are set or cleared according to the dev ice logic. therefore, the result of an instruction with the status register as destination may be different than intended. for example, clrf status will clear the upper three bits and set the z bit. this leaves the status register as 000u u1uu (where u = unchanged). it is recommended, therefore, that only bcf , bsf , swapf , movff and movwf instructions are used to alter the status register, because these instructions do not affect the z, c, dc, ov or n bits from the status regis- ter. for other instructions not affecting any status bits, see table 24-1. register 4-3: status register note: the c and dc bits operate as a borrow and digit borrow bit respectively, in subtraction. u-0 u-0 u-0 r/w-x r/w-x r/w-x r/w-x r/w-x ? ? ?novzdcc bit 7 bit 0 bit 7-5 unimplemented: read as ? 0 ? bit 4 n: negative bit this bit is used for signed arithmetic (2?s complement). it indicates whether the result was negative (alu msb = 1 ). 1 = result was negative 0 = result was positive bit 3 ov: overflow bit this bit is used for signed arithmetic (2?s complement). it indicates an overflow of the 7-bit magnitude, which causes the sign bit (bit 7) to change state. 1 = overflow occurred for signed arithmetic (in this arithmetic operation) 0 = no overflow occurred bit 2 z: zero bit 1 = the result of an arithmetic or logic operation is zero 0 = the result of an arithmetic or logic operation is not zero bit 1 dc: digit carry/borrow bit for addwf , addlw , sublw and subwf instructions: 1 = a carry-out from the 4th low-order bit of the result occurred 0 = no carry-out from the 4th low-order bit of the result note: for borrow, the polarity is reversed. a subtraction is executed by adding the 2?s complement of the second operand. for rotate ( rrf , rlf ) instructions, this bit is loaded with either bit 4 or bit 3 of the source register. bit 0 c: carry/borrow bit for addwf , addlw , sublw and subwf instructions: 1 = a carry-out from the most significant bit of the result occurred 0 = no carry-out from the most significant bit of the result occurred note: for borrow, the polarity is reversed. a subtraction is executed by adding the 2?s complement of the second operand. for rotate ( rrf , rlf ) instructions, this bit is loaded with either the high or low-order bit of the source register. legend: r = readable bit w = writable bit u = unimplemented bit, read as ?0? - n = value at por ?1? = bit is set ?0? = bit is cleared x = bit is unknown
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 60 ? 2004 microchip technology inc. 4.14 rcon register the reset control (rcon) register contains flag bits that allow differentiation between the sources of a device reset. these flags include the to , pd , por , bor and ri bits. this register is readable and writable. register 4-4: rcon register note 1: if the boren configuration bit is set (brown-out reset enabled), the bor bit is ? 1 ? on a power-on reset. after a brown- out reset has occurred, the bor bit will be cleared and must be set by firmware to indicate the occurrence of the next brown-out reset. 2: it is recommended that the por bit be set after a power-on reset has been detected, so that subsequent power-on resets may be detected. r/w-0 u-0 u-0 r/w-1 r/w-1 r/w-1 r/w-0 r/w-0 ipen ? ?ri to pd por bor bit 7 bit 0 bit 7 ipen: interrupt priority enable bit 1 = enable priority levels on interrupts 0 = disable priority levels on interrupts (pic16cxxx compatibility mode) bit 6-5 unimplemented: read as ? 0 ? bit 4 ri : reset instruction flag bit 1 = the reset instruction was not executed 0 = the reset instruction was executed causing a device reset (must be set in software after a brown-out reset occurs) bit 3 to : watchdog time-out flag bit 1 = after power-up, clrwdt instruction, or sleep instruction 0 = a wdt time-out occurred bit 2 pd : power-down detection flag bit 1 = after power-up or by the clrwdt instruction 0 = by execution of the sleep instruction bit 1 por : power-on reset status bit 1 = a power-on reset has not occurred 0 = a power-on reset occurred (must be set in software after a power-on reset occurs) bit 0 bor : brown-out reset status bit 1 = a brown-out reset has not occurred 0 = a brown-out reset occurred (must be set in software after a brown-out reset occurs) legend: r = readable bit w = writable bit u = unimplemented bit, read as ?0? - n = value at por ?1? = bit is set ?0? = bit is cleared x = bit is unknown
? 2004 microchip technology inc. ds39609b-page 61 pic18f6520/8520/6620/8620/6720/8720 5.0 flash program memory the flash program memory is readable, writable and erasable, during normal operation over the entire v dd range. a read from program memory is executed on one byte at a time. a write to program memory is executed on blocks of 8 bytes at a time. program memory is erased in blocks of 64 bytes at a time. a bulk erase operation may not be issued from user code. writing or erasing program memory will cease instruction fetches until the operation is complete. the program memory cannot be accessed during the write or erase, therefore, code cannot execute. an internal programming timer terminates program memory writes and erases. a value written to program memory does not need to be a valid instruction. executing a program memory location that forms an invalid instruction results in a nop . 5.1 table reads and table writes in order to read and write program memory, there are two operations that allow the processor to move bytes between the program memory space and the data ram: table read ( tblrd ) table write ( tblwt ) the program memory space is 16 bits wide, while the data ram space is 8 bits wide. table reads and table writes move data between these two memory spaces through an 8-bit register (tablat). table read operations retrieve data from program mem- ory and place it into the data ram space. figure 5-1 shows the operation of a table read with program memory and data ram. table write operations store data from the data memory space into holding registers in program memory. the procedure to write the contents of the holding registers into program memory is detailed in section 5.5 ?writing to flash program memory? . figure 5-2 shows the operation of a table write with program memory and data ram. table operations work with byte entities. a table block containing data, rather than program instructions, is not required to be word aligned. therefore, a table block can start and end at any byte address. if a table write is being used to write executable code into program memory, program instructions will need to be word aligned. figure 5-1: table read operation table pointer (1) table latch (8-bit) program memory tblptrh tblptrl tablat tblptru instruction: tblrd * note 1: table pointer points to a byte in program memory. program memory (tblptr)
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 62 ? 2004 microchip technology inc. figure 5-2: table write operation 5.2 control registers several control registers are used in conjunction with the tblrd and tblwt instructions. these include the: eecon1 register eecon2 register tablat register tblptr registers 5.2.1 eecon1 and eecon2 registers eecon1 is the control register for memory accesses. eecon2 is not a physical register. reading eecon2 will read all ? 0 ?s. the eecon2 register is used exclusively in the memory write and erase sequences. control bit eepgd determines if the access will be a program or data eeprom memory access. when clear, any subsequent operations will operate on the data eeprom memory. when set, any subsequent operations will operate on the program memory. control bit cfgs determines if the access will be to the configuration/calibration registers, or to program memory/data eeprom memory. when set, subse- quent operations will operate on configuration regis- ters, regardless of eepgd (see section 23.0 ?special features of the cpu? ). when clear, memory selection access is determined by eepgd. the free bit, when set, will allow a program memory erase operation. when the free bit is set, the erase operation is initiated on the next wr command. when free is clear, only writes are enabled. the wren bit, when set, will allow a write operation. on power-up, the wren bit is clear. the wrerr bit is set when a write operation is interrupted by a mclr reset, or a wdt time-out reset during normal opera- tion. in these situations, the user can check the wrerr bit and rewrite the location. it is necessary to reload the data and address registers (eedata and eeadr), due to reset values of zero. the wr control bit, initiates write operations. the bit cannot be cleared, only set, in software; it is cleared in hardware at the completion of the write operation. the inability to clear the wr bit in software prevents the accidental or premature termination of a write operation. table pointer (1) table latch (8-bit) tblptrh tblptrl tablat program memory (tblptr) tblptru instruction: tblwt * note 1: table pointer actually points to one of eight holding registers, the address of which is determined by tblptrl<2:0>. the process for physically writing dat a to the program memory array is discussed in section 5.5 ?writing to flash program memory? . holding registers program memory note: interrupt flag bit, eeif in the pir2 register, is set when the write is complete. it must be cleared in software.
? 2004 microchip technology inc. ds39609b-page 63 pic18f6520/8520/6620/8620/6720/8720 register 5-1: eecon1 register (address fa6h) r/w-x r/w-x u-0 r/w-0 r/w-x r/w-0 r/s-0 r/s-0 eepgd cfgs ? free wrerr wren wr rd bit 7 bit 0 bit 7 eepgd: flash program or data eeprom memory select bit 1 = access flash program memory 0 = access data eeprom memory bit 6 cfgs: flash program/data eeprom or configuration select bit 1 = access configuration registers 0 = access flash program or data eeprom memory bit 5 unimplemented: read as ? 0 ? bit 4 free: flash row erase enable bit 1 = erase the program memory row addressed by tblptr on the next wr command (cleared by completion of erase operation) 0 = perform write only bit 3 wrerr: flash program/data eeprom error flag bit 1 = a write operation is prematurely terminated (any reset during self-timed programming in normal operation) 0 = the write operation completed note: when a wrerr occurs, the eepgd and cfgs bits are not cleared. this allows tracing of the error condition. bit 2 wren: flash program/data eeprom write enable bit 1 = allows write cycles to flash program/data eeprom 0 = inhibits write cycles to flash program/data eeprom bit 1 wr: write control bit 1 = initiates a data eeprom erase/write cycle or a program memory erase cycle or write cycle. (the operation is self-timed and the bit is cleared by hardware once write is complete. the wr bit can only be set (not cleared) in software.) 0 = write cycle to the eeprom is complete bit 0 rd: read control bit 1 = initiates an eeprom read (read takes one cycle. rd is cleared in hardware. the rd bit can only be set (not cleared) in software. rd bit cannot be set when eepgd = 1 .) 0 = does not initiate an eeprom read legend: r = readable bit w = writable bit u = unimplemented bit, read as ?0? - n = value at por ?1? = bit is set ?0? = bit is cleared x = bit is unknown
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 64 ? 2004 microchip technology inc. 5.2.2 tablat ? table latch register the table latch (tablat) is an 8-bit register mapped into the sfr space. the table latch is used to hold 8-bit data during data transfers between program memory and data ram. 5.2.3 tblptr ? table pointer register the table pointer (tblptr) addresses a byte within the program memory. the tblptr is comprised of three sfr registers: table pointer upper byte, table pointer high byte and table pointer low byte (tblptru:tblptrh:tblptrl). these three regis- ters join to form a 22-bit wide pointer. the low-order 21 bits allow the device to address up to 2 mbytes of program memory space. the 22nd bit allows access to the device id, the user id and the configuration bits. the table pointer, tblptr, is used by the tblrd and tblwt instructions. these instructions can update the tblptr in one of four ways, based on the table oper- ation. these operations are shown in table 5-1. these operations on the tblptr only affect the low-order 21 bits. 5.2.4 table pointer boundaries tblptr is used in reads, writes and erases of the flash program memory. when a tblrd is executed, all 22 bits of the table pointer determine which byte is read from program memory into tablat. when a tblwt is executed, the three lsbs of the table pointer (tblptr<2:0>) determine which of the eight program memory holding registers is written to. when the timed write to program memory (long write) begins, the 19 msbs of the table pointer, tblptr (tblptr<21:3>), will determine which program mem- ory block of 8 bytes is written to. for more detail, see section 5.5 ?writing to flash program memory? . when an erase of program memory is executed, the 16 msbs of the table pointer (tblptr<21:6>) point to the 64-byte block that will be erased. the least significant bits (tblptr<5:0>) are ignored. figure 5-3 describes the relevant boundaries of tblptr based on flash program memory operations. table 5-1: table pointer operations with tblrd and tblwt instructions figure 5-3: table pointer boundaries based on operation example operation on table pointer tblrd* tblwt* tblptr is not modified tblrd*+ tblwt*+ tblptr is incremented after the read/write tblrd*- tblwt*- tblptr is decremented after the read/write tblrd+* tblwt+* tblptr is incremented before the read/write 21 16 15 87 0 erase ? tblptr<20:6> write ? tblptr<21:3> read ? tblptr<21:0> tblptrl tblptrh tblptru
? 2004 microchip technology inc. ds39609b-page 65 pic18f6520/8520/6620/8620/6720/8720 5.3 reading the flash program memory the tblrd instruction is used to retrieve data from program memory and places it into data ram. table reads from program memory are performed one byte at a time. tblptr points to a byte address in program space. executing tblrd places the byte pointed to into tablat. in addition, tblptr can be modified automatically for the next table read operation. the internal program memory is typically organized by words. the least significant bit of the address selects between the high and low bytes of the word. figure 5-4 shows the interface between the internal program memory and the tablat. figure 5-4: reads from flash program memory example 5-1: reading a flash program memory word (even byte address) program memory (odd byte address) tblrd tablat tblptr = xxxxx1 fetch instruction register (ir) read register tblptr = xxxxx0 movlw code_addr_upper ; load tblptr with the base movwf tblptru ; address of the word movlw code_addr_high movwf tblptrh movlw code_addr_low movwf tblptrl read_word tblrd*+ ; read into tablat and increment movf tablat, w ; get data movwf word_even tblrd*+ ; read into tablat and increment movfw tablat, w ; get data movwf word_odd
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 66 ? 2004 microchip technology inc. 5.4 erasing flash program memory the minimum erase block is 32 words or 64 bytes. only through the use of an external programmer, or through icsp control, can larger blocks of program memory be bulk erased. word erase in the flash array is not supported. when initiating an erase sequence from the micro- controller itself, a block of 64 bytes of program memory is erased. the most significant 16 bits of the tblptr<21:6> point to the block being erased. tblptr<5:0> are ignored. the eecon1 register commands the erase operation. the eepgd bit must be set to point to the flash pro- gram memory. the wren bit must be set to enable write operations. the free bit is set to select an erase operation. for protection, the write initiate sequence for eecon2 must be used. a long write is necessary for erasing the internal flash. instruction execution is halted while in a long write cycle. the long write will be terminated by the internal programming timer. 5.4.1 flash program memory erase sequence the sequence of events for erasing a block of internal program memory location is: 1. load table pointer with address of row being erased. 2. set the eecon1 register for the erase operation: set eepgd bit to point to program memory; clear the cfgs bit to access program memory; set wren bit to enable writes; set free bit to enable the erase. 3. disable interrupts. 4. write 55h to eecon2. 5. write aah to eecon2. 6. set the wr bit. this will begin the row erase cycle. 7. the cpu will stall for duration of the erase (about 2 ms using internal timer). 8. execute a nop . 9. re-enable interrupts. example 5-2: erasing a flash program memory row movlw code_addr_upper ; load tblptr with the base movwf tblptru ; address of the memory block movlw code_addr_high movwf tblptrh movlw code_addr_low movwf tblptrl erase_row bsf eecon1, eepgd ; point to flash program memory bcf eecon1, cfgs ; access flash program memory bsf eecon1, wren ; enable write to memory bsf eecon1, free ; enable row erase operation bcf intcon, gie ; disable interrupts movlw 55h movwf eecon2 ; write 55h required movlw aah sequence movwf eecon2 ; write aah bsf eecon1, wr ; start erase (cpu stall) nop bsf intcon, gie ; re-enable interrupts
? 2004 microchip technology inc. ds39609b-page 67 pic18f6520/8520/6620/8620/6720/8720 5.5 writing to flash program memory the minimum programming block is 4 words or 8 bytes. word or byte programming is not supported. table writes are used internally to load the holding reg- isters needed to program the flash memory. there are 8 holding registers used by the table writes for programming. since the table latch (tablat) is only a single byte, the tblwt instruction has to be executed 8 times for each programming operation. all of the table write operations will essentially be short writes, because only the holding registers are written. at the end of updating 8 registers, the eecon1 register must be written to, to start the programming operation with a long write. the long write is necessary for programming the inter- nal flash. instruction execution is halted while in a long write cycle. the long write will be terminated by the internal programming timer. the eeprom on-chip timer controls the write time. the write/erase voltages are generated by an on-chip charge pump, rated to operate over the voltage range of the device for byte or word operations. figure 5-5: table writes to flash program memory 5.5.1 flash program memory write sequence the sequence of events for programming an internal program memory location should be: 1. read 64 bytes into ram. 2. update data values in ram as necessary. 3. load table pointer with address being erased. 4. do the row erase procedure. 5. load table pointer with address of first byte being written. 6. write the first 8 bytes into the holding registers with auto-increment. 7. set the eecon1 register for the write operation: set eepgd bit to point to program memory clear the cfgs bit to access program memory set wren to enable byte writes 8. disable interrupts. 9. write 55h to eecon2. 10. write aah to eecon2. 11. set the wr bit. this will begin the write cycle. 12. the cpu will stall for duration of the write (about 2 ms using internal timer). 13. execute a nop . 14. re-enable interrupts. 15. repeat steps 6-14 seven times, to write 64 bytes. 16. verify the memory (table read). this procedure will require about 18 ms to update one row of 64 bytes of memory. an example of the required code is given in example 5-3. holding register tablat holding register tblptr = xxxxx7 holding register tblptr = xxxxx1 holding register tblptr = xxxxx0 8 8 8 8 write register tblptr = xxxxx2 program memory note: before setting the wr bit, the table pointer address needs to be within the intended address range of the eight bytes in the holding register.
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 68 ? 2004 microchip technology inc. example 5-3: writing to flash program memory movlw d?64 ; number of bytes in erase block movwf counter movlw buffer_addr_high ; point to buffer movwf fsr0h movlw buffer_addr_low movwf fsr0l movlw code_addr_upper ; load tblptr with the base movwf tblptru ; address of the memory block movlw code_addr_high movwf tblptrh movlw code_addr_low movwf tblptrl read_block tblrd*+ ; read into tablat, and inc movf tablat, w ; get data movwf postinc0 ; store data decfsz counter ; done? bra read_block ; repeat modify_word movlw data_addr_high ; point to buffer movwf fsr0h movlw data_addr_low movwf fsr0l movlw new_data_low ; update buffer word movwf postinc0 movlw new_data_high movwf indf0 erase_block movlw code_addr_upper ; load tblptr with the base movwf tblptru ; address of the memory block movlw code_addr_high movwf tblptrh movlw code_addr_low movwf tblptrl bsf eecon1, eepgd ; point to flash program memory bcf eecon1, cfgs ; access flash program memory bsf eecon1, wren ; enable write to memory bsf eecon1, free ; enable row erase operation bcf intcon, gie ; disable interrupts movlw 55h movwf eecon2 ; write 55h required movlw aah sequence movwf eecon2 ; write aah bsf eecon1, wr ; start erase (cpu stall) nop bsf intcon, gie ; re-enable interrupts tblrd*- ; dummy read decrement write_buffer_back movlw 8 ; number of write buffer groups of 8 bytes movwf counter_hi movlw buffer_addr_high ; point to buffer movwf fsr0h movlw buffer_addr_low movwf fsr0l program_loop movlw 8 ; number of bytes in holding register movwf counter write_word_to_hregs movff postinc0, wreg ; get low byte of buffer data ; present data to table latch tblwt+* ; write data, perform a short write ; to internal tblwt holding register. decfsz counter ; loop until buffers are full bra write_word_to_hregs
? 2004 microchip technology inc. ds39609b-page 69 pic18f6520/8520/6620/8620/6720/8720 example 5-3: writing to flash program memory (continued) 5.5.2 write verify depending on the application, good programming practice may dictate that the value written to the mem- ory should be verified against the original value. this should be used in applications where excessive writes can stress bits near the specification limit. 5.5.3 unexpected termination of write operation if a write is terminated by an unplanned event, such as loss of power or an unexpected reset, the memory location just programmed should be verified and repro- grammed if needed. the wrerr bit is set when a write operation is interrupted by a mclr reset, or a wdt time-out reset during normal operation. in these situations, users can check the wrerr bit and rewrite the location. 5.5.4 protection against spurious writes to protect against spurious writes to flash program memory, the write initiate sequence must also be followed. see section 23.0 ?special features of the cpu? for more detail. 5.6 flash program operation during code protection see section 23.0 ?special features of the cpu? for details on code protection of flash program memory. table 5-2: registers associated with program flash memory program_memory bsf eecon1, eepgd ; point to flash program memory bcf eecon1, cfgs ; access flash program memory bsf eecon1, wren ; enable write to memory bcf intcon, gie ; disable interrupts movlw 55h movwf eecon2 ; write 55h required movlw aah sequence movwf eecon2 ; write aah bsf eecon1, wr ; start program (cpu stall) nop bsf intcon, gie ; re-enable interrupts decfsz counter_hi ; loop until done bra program_loop bcf eecon1, wren ; disable write to memory name bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 value on por, bor value on all other resets tblptru ? ? bit 21 program memory table pointer upper byte (tblptr<20:16>) --00 0000 --00 0000 tbpltrh program memory table pointer high byte (tblptr<15:8>) 0000 0000 0000 0000 tblptrl program memory table pointer high byte (tblptr<7:0>) 0000 0000 0000 0000 tablat program memory table latch 0000 0000 0000 0000 intcon gie/gieh peie/giel tmr0ie inte rbie tmr0if intf rbif 0000 0000 0000 0000 eecon2 eeprom control register 2 (not a physical register) ? ? eecon1 eepgd cfgs ? free wrerr wren wr rd xx-0 x000 uu-0 u000 ipr2 ? cmip ?eeip bclip lvdip tmr3ip ccp2ip ---1 1111 ---1 1111 pir2 ? cmif ?eeif bclif lvdif tmr3if ccp2if ---0 0000 ---0 0000 pie2 ? cmie ?eeie bclie lvdie tmr3ie ccp2ie ---0 0000 ---0 0000 legend: x = unknown, u = unchanged, r = reserved, - = unimplemented, read as ? 0 ?. shaded cells are not used during flash/eeprom access.
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 70 ? 2004 microchip technology inc. notes:
? 2004 microchip technology inc. ds39609b-page 71 pic18f6520/8520/6620/8620/6720/8720 6.0 external memory interface the external memory interface is a feature of the pic18f8x20 devices that allows the controller to access external memory devices (such as flash, eprom, sram, etc.) as program or data memory. the physical implementation of the interface uses 27 pins. these pins are reserved for external address/data bus functions; they are multiplexed with i/o port pins on four ports. three i/o ports are multiplexed with the address/data bus, while the fourth port is multiplexed with the bus control signals. the i/o port functions are enabled when the ebdis bit in the memcon register is set (see register 6-1). a list of the multiplexed pins and their functions is provided in table 6-1. as implemented in the pic18f8x20 devices, the interface operates in a similar manner to the external memory interface introduced on pic18c601/801 microcontrollers. the most notable difference is that the interface on pic18f8x20 devices only operates in 16-bit modes. the 8-bit mode is not supported. for a more complete discussion of the operating modes that use the external memory interface, refer to section 4.1.1 ?pic18f8x20 program memory modes? . 6.1 program memory modes and the external memory interface as previously noted, pic18f8x20 controllers are capable of operating in any one of four program memory modes, using combinations of on-chip and external program memory. the functions of the multi- plexed port pins depend on the program memory mode selected, as well as the setting of the ebdis bit. in microprocessor mode , the external bus is always active and the port pins have only the external bus function. in microcontroller mode, the bus is not active and the pins have their port functions only. writes to the memcom register are not permitted. in microprocessor with boot block or extended microcontroller mode, the external program memory bus shares i/o port functions on the pins. when the device is fetching or doing table read/table write operations on the external program memory space, the pins will have the external bus function. if the device is fetching and accessing internal program memory loca- tions only, the ebdis control bit will change the pins from external memory to i/o port functions. when ebdis = 0 , the pins function as the external bus. when ebdis = 1 , the pins function as i/o ports. register 6-1: memcon register note: the external memory interface is not implemented on pic18f6x20 (64-pin) devices. note: maximum f osc for the pic18fx520 is limited to 25 mhz when using the external memory interface. r/w-0 u-0 r/w-0 r/w-0 u-0 u-0 r/w-0 r/w-0 ebdis ?wait1wait0 ? ?wm1wm0 bit7 bit0 bit 7 ebdis: external bus disable bit 1 = external system bus disabled, all external bus drivers are mapped as i/o ports 0 = external system bus enabled and i/o ports are disabled bit 6 unimplemented: read as ? 0 ? bit 5-4 wait<1:0>: table reads and writes bus cycle wait count bits 11 = table reads and writes will wait 0 t cy 10 = table reads and writes will wait 1 t cy 01 = table reads and writes will wait 2 t cy 00 = table reads and writes will wait 3 t cy bit 3-2 unimplemented: read as ? 0 ? bit 1-0 wm<1:0>: tblwrt operation with 16-bit bus bits 1x = word write mode: tablat<0> and tablat<1> word output, wrh active when tablat<1> written 01 = byte select mode: tablat data copied on both msb and lsb, wrh and (ub or lb ) will activate 00 = byte write mode: tablat data copied on both msb and lsb, wrh or wrl will activate legend: r = readable bit w = writable bit u = unimplemented bit, read as ?0? - n = value at por ?1? = bit is set ?0? = bit is cleared x = bit is unknown
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 72 ? 2004 microchip technology inc. if the device fetches or accesses external memory while ebdis = 1 , the pins will switch to external bus. if the ebdis bit is set by a program executing from external memory, the action of setting the bit will be delayed until the program branches into the internal memory. at that time, the pins will change from external bus to i/o ports. when the device is executing out of internal memory (ebdis = 0 ) in microprocessor with boot block mode, or extended microcontroller mode, the control signals will not be active. they will go to a state where the ad<15:0> and a<19:16> are tri-state; the ce , oe , wrh , wrl , ub and lb signals are ? 1 ? and ale and ba0 are ? 0 ?. table 6-1: pic18f8x20 external bus ? i/o port functions name port bit function rd0/ad0 portd bit 0 input/output or system bus address bit 0 or data bit 0. rd1/ad1 portd bit 1 input/output or system bus address bit 1 or data bit 1. rd2/ad2 portd bit 2 input/output or system bus address bit 2 or data bit 2. rd3/ad3 portd bit 3 input/output or system bus address bit 3 or data bit 3. rd4/ad4 portd bit 4 input/output or system bus address bit 4 or data bit 4. rd5/ad5 portd bit 5 input/output or system bus address bit 5 or data bit 5. rd6/ad6 portd bit 6 input/output or system bus address bit 6 or data bit 6. rd7/ad7 portd bit 7 input/output or system bus address bit 7 or data bit 7. re0/ad8 porte bit 0 input/output or system bus address bit 8 or data bit 8. re1/ad9 porte bit 1 input/output or system bus address bit 9 or data bit 9. re2/ad10 porte bit 2 input/output or system bus address bit 10 or data bit 10. re3/ad11 porte bit 3 input/output or system bus address bit 11 or data bit 11. re4/ad12 porte bit 4 input/output or system bus address bit 12 or data bit 12. re5/ad13 porte bit 5 input/output or system bus address bit 13 or data bit 13. re6/ad14 porte bit 6 input/output or system bus address bit 14 or data bit 14. re7/ad15 porte bit 7 input/output or system bus address bit 15 or data bit 15. rh0/a16 porth bit 0 input/output or system bus address bit 16. rh1/a17 porth bit 1 input/output or system bus address bit 17. rh2/a18 porth bit 2 input/output or system bus address bit 18. rh3/a19 porth bit 3 input/output or system bus address bit 19. rj0/ale portj bit 0 input/output or system bus address latch enable (ale) control pin. rj1/oe portj bit 1 input/output or system bus output enable (oe ) control pin. rj2/wrl portj bit 2 input/output or system bus write low (wrl ) control pin. rj3/wrh portj bit 3 input/output or system bus write high (wrh ) control pin. rj4/ba0 portj bit 4 input/output or system bus byte address bit 0. rj5/ce portj bit 5 input/output or system bus chip enable (ce ) control pin. rj6/lb portj bit 6 input/output or system bus lower byte enable (lb ) control pin. rj7/ub portj bit 7 input/output or system bus upper byte enable (ub ) control pin.
? 2004 microchip technology inc. ds39609b-page 73 pic18f6520/8520/6620/8620/6720/8720 6.2 16-bit mode the external memory interface implemented in pic18f8x20 devices operates only in 16-bit mode. the mode selection is not software configurable, but is programmed via the configuration bits. the wm<1:0> bits in the memcon register determine three types of connections in 16-bit mode. they are referred to as: 16-bit byte write 16-bit word write 16-bit byte select these three different configurations allow the designer maximum flexibility in using 8-bit and 16-bit memory devices. for all 16-bit modes, the address latch enable (ale) pin indicates that the address bits a<15:0> are available on the external memory interface bus. following the address latch, the output enable signal (oe ) will enable both bytes of program memory at once to form a 16-bit instruction word. the chip enable signal (ce ) is active at any time that the microcontroller accesses external memory, whether reading or writing; it is inactive (asserted high) whenever the device is in sleep mode. in byte select mode, jedec standard flash memories will require ba0 for the byte address line and one i/o line to select between byte and word mode. the other 16-bit modes do not need ba0. jedec standard static ram memories will use the ub or lb signals for byte selection. 6.2.1 16-bit byte write mode figure 6-1 shows an example of 16-bit byte write mode for pic18f8x20 devices. this mode is used for two separate 8-bit memories connected for 16-bit oper- ation. this generally includes basic eprom and flash devices. it allows table writes to byte-wide external memories. during a tblwt instruction cycle, the tablat data is presented on the upper and lower bytes of the ad15:ad0 bus. the appropriate wrh or wrl control line is strobed on the lsb of the tblptr. figure 6-1: 16-bit byte write mode example ad<7:0> a<19:16> ale d<15:8> 373 a d<7:0> a<19:0> a d<7:0> 373 oe wrh oe oe wr (1) wr (1) ce ce note 1: this signal only applies to table writes. see section 5.1 ?table reads and table writes? . wrl d<7:0> (lsb) (msb) pic18f8x20 d<7:0> ad<15:8> address bus data bus control lines ce
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 74 ? 2004 microchip technology inc. 6.2.2 16-bit word write mode figure 6-2 shows an example of 16-bit word write mode for pic18f8x20 devices. this mode is used for word-wide memories, which includes some of the eprom and flash type memories. this mode allows opcode fetches and table reads from all forms of 16-bit memory and table writes to any type of word-wide external memories. this method makes a distinction between tblwt cycles to even or odd addresses. during a tblwt cycle to an even address (tblptr<0> = 0 ), the tablat data is transferred to a holding latch and the external address data bus is tri-stated for the data portion of the bus cycle. no write signals are activated. during a tblwt cycle to an odd address (tblptr<0> = 1 ), the tablat data is presented on the upper byte of the ad15:ad0 bus. the contents of the holding latch are presented on the lower byte of the ad15:ad0 bus. the wrh signal is strobed for each write cycle; the wrl pin is unused. the signal on the ba0 pin indicates the lsb of tblptr, but it is left unconnected. instead, the ub and lb signals are active to select both bytes. the obvious limitation to this method is that the table write must be done in pairs on a specific word boundary to correctly write a word location. figure 6-2: 16-bit word write mode example ad<7:0> pic18f8x20 ad<15:8> ale 373 a<20:1> 373 oe wrh a<19:16> a d<15:0> oe wr (1) ce d<15:0> jedec word eprom memory address bus data bus control lines note 1: this signal only applies to table writes. see section 5.1 ?table reads and table writes? . ce
? 2004 microchip technology inc. ds39609b-page 75 pic18f6520/8520/6620/8620/6720/8720 6.2.3 16-bit byte select mode figure 6-3 shows an example of 16-bit byte select mode for pic18f8x20 devices. this mode allows table write operations to word-wide external memories with byte selection capability. this generally includes both word-wide flash and sram devices. during a tblwt cycle, the tablat data is presented on the upper and lower byte of the ad15:ad0 bus. the wrh signal is strobed for each write cycle; the wrl pin is not used. the ba0 or ub /lb signals are used to select the byte to be written, based on the least significant bit of the tblptr register. flash and sram devices use different control signal combinations to implement byte select mode. jedec standard flash memories require that a controller i/o port pin be connected to the memory?s byte/word pin to provide the select signal. they also use the ba0 signal from the controller as a byte address. jedec standard static ram memories, on the other hand, use the ub or lb signals to select the byte. figure 6-3: 16-bit byte select mode example ad<7:0> pic18f8x20 ad<15:8> ale 373 a<20:1> 373 oe wrh a<19:16> wrl ba0 jedec word a d<15:0> a<20:1> ce d<15:0> i/o oe wr (1) a0 byte/word flash memory jedec word a d<15:0> ce d<15:0> oe wr (1) lb ub sram memory lb ub 138 address bus data bus control lines note 1: this signal only applies to table writes. see section 5.1 ?table reads and table writes? .
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 76 ? 2004 microchip technology inc. 6.2.4 16-bit mode timing the presentation of control signals on the external memory bus is different for the various operating modes. typical signal timing diagrams are shown in figure 6-4 through figure 6-6. figure 6-4: external me mory bus timing for tblrd (microprocessor mode) figure 6-5: external memory bus timing for tblrd (extended microcontroller mode) q2 q1 q3 q4 q2 q1 q3 q4 q4 q4 q4 q4 ale oe 3aabh wrh wrl ad<15:0> ba0 cf33h 9256h 0e55h ? 1 ? ? 1 ? ? 1 ? ? 1 ? table read of 92h from 199e67h 1 t cy wait q2 q1 q3 q4 q2 q1 q3 q4 q2 q1 q3 q4 apparent q actual q a<19:16> 0ch 00h ce ? 0 ? ? 0 ? memory cycle instruction execution tblrd cycle 1 tblrd cycle 2 opcode fetch movlw 55h from 007556h q2 q1 q3 q4 q2 q1 q3 q4 q2 q1 q3 q4 a<19:16> ale oe ad<15:0> ce opcode fetch opcode fetch opcode fetch tblrd * tblrd cycle 1 addlw 55h from 000100h q2 q1 q3 q4 0ch cf33h tblrd 92h from 199e67h 9256h from 000104h memory cycle instruction execution inst(pc-2) tblrd cycle 2 movlw 55h from 000102h movlw
? 2004 microchip technology inc. ds39609b-page 77 pic18f6520/8520/6620/8620/6720/8720 figure 6-6: external me mory bus timing for sleep (microprocessor mode) q2 q1 q3 q4 q2 q1 q3 q4 a<19:16> ale oe 3aaah ad<15:0> 00h 00h ce opcode fetch opcode fetch sleep sleep from 007554h q1 bus inactive 0003h 3aabh 0e55h memory cycle instruction execution inst(pc-2) sleep mode, movlw 55h from 007556h
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 78 ? 2004 microchip technology inc. notes:
? 2004 microchip technology inc. ds39609b-page 79 pic18f6520/8520/6620/8620/6720/8720 7.0 data eeprom memory the data eeprom is readable and writable during normal operation over the entire v dd range. the data memory is not directly mapped in the register file space. instead, it is indirectly addressed through the special function registers (sfr). there are five sfrs used to read and write the program and data eeprom memory. these registers are: eecon1 eecon2 eedata eeadrh eeadr the eeprom data memory allows byte read and write. when interfacing to the data memory block, eedata holds the 8-bit data for read/write. eeadr and eeadrh hold the address of the eeprom location being accessed. these devices have 1024 bytes of data eeprom with an address range from 00h to 3ffh. the eeprom data memory is rated for high erase/ write cycles. a byte write automatically erases the loca- tion and writes the new data (erase-before-write). the write time is controlled by an on-chip timer. the write time will vary with voltage and temperature, as well as from chip to chip. please refer to parameter d122 (see section 26.0 ?electrical characteristics? ) for exact limits. 7.1 eeadr and eeadrh the address register pair can address up to a maxi- mum of 1024 bytes of data eeprom. the two most significant bits of the address are stored in eeadrh, while the remaining eight least significant bits are stored in eeadr. the six most significant bits of eeadrh are unused and are read as ? 0 ?. 7.2 eecon1 and eecon2 registers eecon1 is the control register for eeprom memory accesses. eecon2 is not a physical register. reading eecon2 will read all ? 0 ?s. the eecon2 register is used exclusively in the eeprom write sequence. control bits, rd and wr, initiate read and write opera- tions, respectively. these bits cannot be cleared, only set, in software. they are cleared in hardware at the completion of the read or write operation. the inability to clear the wr bit in software prevents the accidental or premature termination of a write operation. the wren bit, when set, will allow a write operation. on power-up, the wren bit is clear. the wrerr bit is set when a write operation is interrupted by a mclr reset or a wdt time-out reset during normal opera- tion. in these situations, the user can check the wrerr bit and rewrite the location. it is necessary to reload the data and address registers (eedata and eeadr) due to the reset condition forcing the contents of the registers to zero. note: interrupt flag bit, eeif in the pir2 register, is set when write is complete. it must be cleared in software.
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 80 ? 2004 microchip technology inc. register 7-1: eecon1 register (address fa6h) r/w-x r/w-x u-0 r/w-0 r/w-x r/w-0 r/s-0 r/s-0 eepgd cfgs ? free wrerr wren wr rd bit 7 bit 0 bit 7 eepgd: flash program/data eeprom memory select bit 1 = access flash program memory 0 = access data eeprom memory bit 6 cfgs: flash program/data eeprom or configuration select bit 1 = access configuration or calibration registers 0 = access flash program or data eeprom memory bit 5 unimplemented: read as ? 0 ? bit 4 free: flash row erase enable bit 1 = erase the program memory row addressed by tblptr on the next wr command (cleared by completion of erase operation) 0 = perform write only bit 3 wrerr: flash program/data eeprom error flag bit 1 = a write operation is prematurely terminated (any mclr or any wdt reset during self-timed programming in normal operation) 0 = the write operation completed note: when a wrerr occurs, the eepgd or free bits are not cleared. this allows tracing of the error condition. bit 2 wren: flash program/data eeprom write enable bit 1 = allows write cycles to flash program/data eeprom 0 = inhibits write cycles to flash program/data eeprom bit 1 wr: write control bit 1 = initiates a data eeprom erase/write cycle, or a program memory erase cycle or write cycle. (the operation is self-timed and the bit is cleared by hardware once write is complete. the wr bit can only be set (not cleared) in software.) 0 = write cycle to the eeprom is complete bit 0 rd: read control bit 1 = initiates an eeprom read. (read takes one cycle. rd is cleared in hardware. the rd bit can only be set (not cleared) in software. rd bit cannot be set when eepgd = 1 .) 0 = does not initiate an eeprom read legend: r = readable bit w = writable bit u = unimplemented bit, read as ?0? - n = value at por ?1? = bit is set ?0? = bit is cleared x = bit is unknown
? 2004 microchip technology inc. ds39609b-page 81 pic18f6520/8520/6620/8620/6720/8720 7.3 reading the data eeprom memory to read a data memory location, the user must write the address to the eeadrh:eeadr register pair, clear the eepgd control bit (eecon1<7>), clear the cfgs control bit (eecon1<6>) and then set the rd control bit (eecon1<0>). the data is available for the very next instruction cycle; therefore, the eedata register can be read by the next instruction. eedata will hold this value until another read operation, or until it is written to by the user (during a write operation). example 7-1: data eeprom read 7.4 writing to the data eeprom memory to write an eeprom data location, the address must first be written to the eeadrh:eeadr register pair and the data written to the eedata register. then the sequence in example 7-2 must be followed to initiate the write cycle. the write will not initiate if the above sequence is not exactly followed (write 55h to eecon2, write aah to eecon2, then set wr bit) for each byte. it is strongly recommended that interrupts be disabled during this code segment. additionally, the wren bit in eecon1 must be set to enable writes. this mechanism prevents accidental writes to data eeprom due to unexpected code execution (i.e., runaway programs). the wren bit should be kept clear at all times, except when updating the eeprom. the wren bit is not cleared by hardware after a write sequence has been initiated, eecon1, eeadrh, eeadr and eedata cannot be modified. the wr bit will be inhibited from being set unless the wren bit is set. both wr and wren cannot be set with the same instruction. at the completion of the write cycle, the wr bit is cleared in hardware and the eeprom write complete interrupt flag bit (eeif) is set. the user may either enable this interrupt, or poll this bit. eeif must be cleared by software. example 7-2: data eeprom write movlw data_ee_addrh ; movwf eeadrh ; upper bits of data memory address to read movlw data_ee_addr ; movwf eeadr ; lower bits of data memory address to read bcf eecon1, eepgd ; point to data memory bcf eecon1, cfgs ; access eeprom bsf eecon1, rd ; eeprom read movf eedata, w ; w = eedata movlw data_ee_addrh ; movwf eeadrh ; upper bits of data memory address to write movlw data_ee_addr ; movwf eeadr ; lower bits of data memory address to write movlw data_ee_data ; movwf eedata ; data memory value to write bcf eecon1, eepgd ; point to data memory bcf eecon1, cfgs ; access eeprom bsf eecon1, wren ; enable writes bcf intcon, gie ; disable interrupts movlw 55h ; required movwf eecon2 ; write 55h sequence movlw aah ; movwf eecon2 ; write aah bsf eecon1, wr ; set wr bit to begin write bsf intcon, gie ; enable interrupts ; user code execution bcf eecon1, wren ; disable writes on write complete (eeif set)
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 82 ? 2004 microchip technology inc. 7.5 write verify depending on the application, good programming practice may dictate that the value written to the mem- ory should be verified against the original value. this should be used in applications where excessive writes can stress bits near the specification limit. 7.6 protection against spurious write there are conditions when the user may not want to write to the data eeprom memory. to protect against spurious eeprom writes, various mechanisms have been built-in. on power-up, the wren bit is cleared. also, the power-up timer (72 ms duration) prevents eeprom write. the write initiate sequence and the wren bit together help prevent an accidental write during brown-out, power glitch, or software malfunction. 7.7 operation during code-protect data eeprom memory has its own code-protect mechanism. external read and write operations are disabled if either of these mechanisms are enabled. the microcontroller itself can both read and write to the internal data eeprom, regardless of the state of the code-protect configuration bit. refer to section 23.0 ?special features of the cpu? for additional information. 7.8 using the data eeprom the data eeprom is a high endurance, byte address- able array that has been optimized for the storage of frequently changing information (e.g., program vari- ables or other data that are updated often). frequently changing values will typically be updated more often than specification d124. if this is not the case, an array refresh must be performed. for this reason, variables that change infrequently (such as constants, ids, calibration, etc.) should be stored in flash program memory. a simple data eeprom refresh routine is shown in example 7-3. example 7-3: data eeprom refresh routine note: if data eeprom is only used to store constants and/or data that changes rarely, an array refresh is likely not required. see specification d124. clrf eeadr ; start at address 0 clrf eeadrh ; bcf eecon1, cfgs ; set for memory bcf eecon1, eepgd ; set for data eeprom bcf intcon, gie ; disable interrupts bsf eecon1, wren ; enable writes loop ; loop to refresh array bsf eecon1, rd ; read current address movlw 55h ; movwf eecon2 ; write 55h movlw aah ; movwf eecon2 ; write aah bsf eecon1, wr ; set wr bit to begin write btfsc eecon1, wr ; wait for write to complete bra $-2 incfsz eeadr, f ; increment address bra loop ; not zero, do it again incfsz eeadrh, f ; increment the high address bra loop ; not zero, do it again bcf eecon1, wren ; disable writes bsf intcon, gie ; enable interrupts
? 2004 microchip technology inc. ds39609b-page 83 pic18f6520/8520/6620/8620/6720/8720 table 7-1: registers associated with data eeprom memory name bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 value on por, bor value on all other resets intcon gie/gieh peie/giel tmr0ie int0ie rbie tmr0if int0if rbif 0000 0000 0000 0000 eeadrh ? ? ? ? ? ? ee addr register high ---- --00 ---- --00 eeadr eeprom address register 0000 0000 0000 0000 eedata eeprom data register 0000 0000 0000 0000 eecon2 eeprom control register 2 (not a physical register) ---- ---- ---- ---- eecon1 eepgd cfgs ? free wrerr wren wr rd xx-0 x000 uu-0 u000 ipr2 ? cmip ?eeip bclip lvdip tmr3ip ccp2ip ---1 1111 ---1 1111 pir2 ? cmif ?eeif bclif lvdif tmr3if ccp2if ---0 0000 ---0 0000 pie2 ? cmie ?eeie bclie lvdie tmr3ie ccp2ie ---0 0000 ---0 0000 legend: x = unknown, u = unchanged, r = reserved, ? = unimplemented, read as ? 0 ?. shaded cells are not used during flash/eeprom access.
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 84 ? 2004 microchip technology inc. notes:
? 2004 microchip technology inc. ds39609b-page 85 pic18f6520/8520/6620/8620/6720/8720 8.0 8 x 8 hardware multiplier 8.1 introduction an 8 x 8 hardware multiplier is included in the alu of the pic18fxx20 devices. by making the multiply a hardware operation, it completes in a single instruction cycle. this is an unsigned multiply that gives a 16-bit result. the result is stored in the 16-bit product register pair (prodh:prodl). the multiplier does not affect any flags in the alusta register. making the 8 x 8 multiplier execute in a single cycle gives the following advantages: higher computational throughput reduces code size requirements for multiply algorithms the performance increase allows the device to be used in applications previously reserved for digital signal processors. table 8-1 shows a performance comparison between enhanced devices using the single-cycle hardware multiply and performing the same function without the hardware multiply. 8.2 operation example 8-1 shows the sequence to do an 8 x 8 unsigned multiply. only one instruction is required when one argument of the multiply is already loaded in the wreg register. example 8-2 shows the sequence to do an 8 x 8 signed multiply. to account for the sign bits of the arguments, each argument?s most significant bit (msb) is tested and the appropriate subtractions are done. example 8-1: 8 x 8 unsigned multiply routine example 8-2: 8 x 8 signed multiply routine table 8-1: performance comparison movf arg1, w ; mulwf arg2 ; arg1 * arg2 -> ; prodh:prodl movf arg1, w ; mulwf arg2 ; arg1 * arg2 -> ; prodh:prodl btfsc arg2, sb ; test sign bit subwf prodh, f ; prodh = prodh ; - arg1 movf arg2, w ; btfsc arg1, sb ; test sign bit subwf prodh, f ; prodh = prodh ; - arg2 routine multiply method program memory (words) cycles (max) time @ 40 mhz @ 10 mhz @ 4 mhz 8 x 8 unsigned without hardware multiply 13 69 6.9 s27.6 s69 s hardware multiply 1 1 100 ns 400 ns 1 s 8 x 8 signed without hardware multiply 33 91 9.1 s36.4 s91 s hardware multiply 6 6 600 ns 2.4 s6 s 16 x 16 unsigned without hardware multiply 21 242 24.2 s96.8 s242 s hardware multiply 28 28 2.8 s 11.2 s28 s 16 x 16 signed without hardware multiply 52 254 25.4 s 102.6 s254 s hardware multiply 35 40 4.0 s16.0 s40 s
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 86 ? 2004 microchip technology inc. example 8-3 shows the sequence to do a 16 x 16 unsigned multiply. equation 8-1 shows the algorithm that is used. the 32-bit result is stored in four registers, res3:res0. equation 8-1: 16 x 16 unsigned multiplication algorithm example 8-3: 16 x 16 unsigned multiply routine example 8-4 shows the sequence to do a 16 x 16 signed multiply. equation 8-2 shows the algorithm used. the 32-bit result is stored in four registers, res3:res0. to account for the sign bits of the argu- ments, each argument pairs? most significant bit (msb) is tested and the appropriate subtractions are done. equation 8-2: 16 x 16 signed multiplication algorithm example 8-4: 16 x 16 signed multiply routine movf arg1l, w mulwf arg2l ; arg1l * arg2l -> ; prodh:prodl movff prodh, res1 ; movff prodl, res0 ; ; movf arg1h, w mulwf arg2h ; arg1h * arg2h -> ; prodh:prodl movff prodh, res3 ; movff prodl, res2 ; ; movf arg1l, w mulwf arg2h ; arg1l * arg2h -> ; prodh:prodl movf prodl, w ; addwf res1, f ; add cross movf prodh, w ; products addwfc res2, f ; clrf wreg ; addwfc res3, f ; ; movf arg1h, w ; mulwf arg2l ; arg1h * arg2l -> ; prodh:prodl movf prodl, w ; addwf res1, f ; add cross movf prodh, w ; products addwfc res2, f ; clrf wreg ; addwfc res3, f ; res3:res0 = arg1h:arg1l ? arg2h:arg2l = (arg1h ? arg2h ? 2 16 ) + (arg1h ? arg2l ? 2 8 ) + (arg1l ? arg2h ? 2 8 ) + (arg1l ? arg2l) movf arg1l, w mulwf arg2l ; arg1l * arg2l -> ; prodh:prodl movff prodh, res1 ; movff prodl, res0 ; ; movf arg1h, w mulwf arg2h ; arg1h * arg2h -> ; prodh:prodl movff prodh, res3 ; movff prodl, res2 ; ; movf arg1l, w mulwf arg2h ; arg1l * arg2h -> ; prodh:prodl movf prodl, w ; addwf res1, f ; add cross movf prodh, w ; products addwfc res2, f ; clrf wreg ; addwfc res3, f ; ; movf arg1h, w ; mulwf arg2l ; arg1h * arg2l -> ; prodh:prodl movf prodl, w ; addwf res1, f ; add cross movf prodh, w ; products addwfc res2, f ; clrf wreg ; addwfc res3, f ; ; btfss arg2h, 7 ; arg2h:arg2l neg? bra sign_arg1 ; no, check arg1 movf arg1l, w ; subwf res2 ; movf arg1h, w ; subwfb res3 ; sign_arg1 btfss arg1h, 7 ; arg1h:arg1l neg? bra cont_code ; no, done movf arg2l, w ; subwf res2 ; movf arg2h, w ; subwfb res3 ; cont_code : res3:res0 = arg1h:arg1l ? arg2h:arg2l = (arg1h ? arg2h ? 2 16 ) + (arg1h ? arg2l ? 2 8 ) + (arg1l ? arg2h ? 2 8 ) + (arg1l ? arg2l) + (-1 ? arg2h<7> ? arg1h:arg1l ? 2 16 ) + (-1 ? arg1h<7> ? arg2h:arg2l ? 2 16 )
? 2004 microchip technology inc. ds39609b-page 87 pic18f6520/8520/6620/8620/6720/8720 9.0 interrupts the pic18fxx20 devices have multiple interrupt sources and an interrupt priority feature that allows each interrupt source to be assigned a high or a low priority level. the high priority interrupt vector is at 000008h, while the low priority interrupt vector is at 000018h. high priority interrupt events will override any low priority interrupts that may be in progress. there are thirteen registers which are used to control interrupt operation. they are: rcon intcon intcon2 intcon3 pir1, pir2, pir3 pie1, pie2, pie3 ipr1, ipr2, ipr3 it is recommended that the microchip header files, supplied with mplab ? ide, be used for the symbolic bit names in these registers. this allows the assembler/ compiler to automatically take care of the placement of these bits within the specified register. each interrupt source has three bits to control its operation. the functions of these bits are: flag bit to indicate that an interrupt event occurred enable bit that allows program execution to branch to the interrupt vector address when the flag bit is set priority bit to select high priority or low priority the interrupt priority feature is enabled by setting the ipen bit (rcon<7>). when interrupt priority is enabled, there are two bits which enable interrupts globally. setting the gieh bit (intcon<7>) enables all interrupts that have the priority bit set. setting the giel bit (intcon<6>) enables all interrupts that have the priority bit cleared. when the interrupt flag, enable bit and appropriate global interrupt enable bit are set, the interrupt will vector immediately to address 000008h or 000018h, depending on the priority level. individual interrupts can be disabled through their corresponding enable bits. when the ipen bit is cleared (default state), the interrupt priority feature is disabled and interrupts are compatible with picmicro ? mid-range devices. in com- patibility mode, the interrupt priority bits for each source have no effect. intcon<6> is the peie bit, which enables/disables all peripheral interrupt sources. intcon<7> is the gie bit, which enables/disables all interrupt sources. all interrupts branch to address 000008h in compatibility mode. when an interrupt is responded to, the global interrupt enable bit is cleared to disable further interrupts. if the ipen bit is cleared, this is the gie bit. if interrupt priority levels are used, this will be either the gieh or giel bit. high priority interrupt sources can interrupt a low priority interrupt. the return address is pushed onto the stack and the pc is loaded with the interrupt vector address (000008h or 000018h). once in the interrupt service routine, the source(s) of the interrupt can be deter- mined by polling the interrupt flag bits. the interrupt flag bits must be cleared in software before re-enabling interrupts to avoid recursive interrupts. the ?return from interrupt? instruction, retfie , exits the interrupt routine and sets the gie bit (gieh or giel if priority levels are used), which re-enables interrupts. for external interrupt events, such as the int pins or the portb input change interrupt, the interrupt latency will be three to four instruction cycles. the exact latency is the same for one or two-cycle instructions. individual interrupt flag bits are set, regardless of the status of their corresponding enable bit or the gie bit.
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 88 ? 2004 microchip technology inc. figure 9-1: interrupt logic tmr0ie gieh/gie giel/peie wake-up if in sleep mode interrupt to cpu vector to location 0008h int2if int2ie int2ip int1if int1ie int1ip tmr0if tmr0ie tmr0ip rbif rbie rbip ipen tmr0if tmr0ip int1if int1ie int1ip int2if int2ie int2ip rbif rbie rbip int0if int0ie giel/peie interrupt to cpu vector to location ipen ipen 0018h peripheral interrupt flag bit peripheral interrupt enable bit peripheral interrupt priority bit peripheral interrupt flag bit peripheral interrupt enable bit peripheral interrupt priority bit tmr1if tmr1ie tmr1ip xxxxif xxxxie xxxxip additional peripheral interrupts tmr1if tmr1ie tmr1ip high priority interrupt generation low priority interrupt generation xxxxif xxxxie xxxxip additional peripheral interrupts gie/geih
? 2004 microchip technology inc. ds39609b-page 89 pic18f6520/8520/6620/8620/6720/8720 9.1 intcon registers the intcon registers are readable and writable registers, which contain various enable, priority and flag bits. register 9-1: intcon register note: interrupt flag bits are set when an interrupt condition occurs, regardless of the state of its corresponding enable bit or the global enable bit. user software should ensure the appropriate interrupt flag bits are clear prior to enabling an interrupt. this feature allows for software polling. r/w-0 r/w-0 r/w-0 r/w-0 r/w-0 r/w-0 r/w-0 r/w-x gie/gieh peie/giel tmr0ie int0ie rbie tmr0if int0if rbif bit 7 bit 0 bit 7 gie/gieh: global interrupt enable bit when ipen (rcon<7>) = 0 : 1 = enables all unmasked interrupts 0 = disables all interrupts when ipen (rcon<7>) = 1 : 1 = enables all high priority interrupts 0 = disables all interrupts bit 6 peie/giel: peripheral interrupt enable bit when ipen (rcon<7>) = 0 : 1 = enables all unmasked peripheral interrupts 0 = disables all peripheral interrupts when ipen (rcon<7>) = 1 : 1 = enables all low priority peripheral interrupts 0 = disables all low priority peripheral interrupts bit 5 tmr0ie: tmr0 overflow interrupt enable bit 1 = enables the tmr0 overflow interrupt 0 = disables the tmr0 overflow interrupt bit 4 int0ie: int0 external interrupt enable bit 1 = enables the int0 external interrupt 0 = disables the int0 external interrupt bit 3 rbie: rb port change interrupt enable bit 1 = enables the rb port change interrupt 0 = disables the rb port change interrupt bit 2 tmr0if: tmr0 overflow interrupt flag bit 1 = tmr0 register has overflowed (must be cleared in software) 0 = tmr0 register did not overflow bit 1 int0if: int0 external interrupt flag bit 1 = the int0 external interrupt occurred (must be cleared in software) 0 = the int0 external interrupt did not occur bit 0 rbif: rb port change interrupt flag bit 1 = at least one of the rb7:rb4 pins changed state (must be cleared in software) 0 = none of the rb7:rb4 pins have changed state note: a mismatch condition will continue to set this bit. reading portb will end the mismatch condition and allow the bit to be cleared. legend: r = readable bit w = writable bit u = unimplemented bit, read as ?0? - n = value at por ?1? = bit is set ?0? = bit is cleared x = bit is unknown
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 90 ? 2004 microchip technology inc. register 9-2: intcon2 register r/w-1 r/w-1 r/w-1 r/w-1 r/w-1 r/w-1 r/w-1 r/w-1 rbpu intedg0 intedg1 intedg2 i ntedg3 tmr0ip int3ip rbip bit 7 bit 0 bit 7 rbpu : portb pull-up enable bit 1 = all portb pull-ups are disabled 0 = portb pull-ups are enabled by individual port latch values bit 6 intedg0: external interrupt 0 edge select bit 1 = interrupt on rising edge 0 = interrupt on falling edge bit 5 intedg1: external interrupt 1 edge select bit 1 = interrupt on rising edge 0 = interrupt on falling edge bit 4 intedg2: external interrupt 2 edge select bit 1 = interrupt on rising edge 0 = interrupt on falling edge bit 3 intedg3: external interrupt 3 edge select bit 1 = interrupt on rising edge 0 = interrupt on falling edge bit 2 tmr0ip: tmr0 overflow interrupt priority bit 1 = high priority 0 = low priority bit 1 int3ip: int3 external interrupt priority bit 1 = high priority 0 = low priority bit 0 rbip: rb port change interrupt priority bit 1 = high priority 0 = low priority legend: r = readable bit w = writable bit u = unimplemented bit, read as ?0? - n = value at por ?1? = bit is set ?0? = bit is cleared x = bit is unknown note: interrupt flag bits are set when an interrupt condition occurs, regardless of the state of its corresponding enable bit or the global enable bit. user software should ensure the appropriate interrupt flag bits are clear prior to enabling an interrupt. this feature allows for software polling.
? 2004 microchip technology inc. ds39609b-page 91 pic18f6520/8520/6620/8620/6720/8720 register 9-3: intcon3 register r/w-1 r/w-1 r/w-0 r/w-0 r/w-0 r/w-0 r/w-0 r/w-0 int2ip int1ip int3ie int2ie int1ie int3if int2if int1if bit 7 bit 0 bit 7 int2ip: int2 external interrupt priority bit 1 = high priority 0 = low priority bit 6 int1ip: int1 external interrupt priority bit 1 = high priority 0 = low priority bit 5 int3ie: int3 external interrupt enable bit 1 = enables the int3 external interrupt 0 = disables the int3 external interrupt bit 4 int2ie: int2 external interrupt enable bit 1 = enables the int2 external interrupt 0 = disables the int2 external interrupt bit 3 int1ie: int1 external interrupt enable bit 1 = enables the int1 external interrupt 0 = disables the int1 external interrupt bit 2 int3if: int3 external interrupt flag bit 1 = the int3 external interrupt occurred (must be cleared in software) 0 = the int3 external interrupt did not occur bit 1 int2if: int2 external interrupt flag bit 1 = the int2 external interrupt occurred (must be cleared in software) 0 = the int2 external interrupt did not occur bit 0 int1if: int1 external interrupt flag bit 1 = the int1 external interrupt occurred (must be cleared in software) 0 = the int1 external interrupt did not occur legend: r = readable bit w = writable bit u = unimplemented bit, read as ?0? - n = value at por ?1? = bit is set ?0? = bit is cleared x = bit is unknown note: interrupt flag bits are set when an interrupt condition occurs, regardless of the state of its corresponding enable bit or the global enable bit. user software should ensure the appropriate interrupt flag bits are clear prior to enabling an interrupt. this feature allows for software polling.
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 92 ? 2004 microchip technology inc. 9.2 pir registers the pir registers contain the individual flag bits for the peripheral interrupts. due to the number of peripheral interrupt sources, there are three peripheral interrupt flag registers (pir1, pir2 and pir3). register 9-4: pir1: peripheral interrupt request (flag) register 1 note 1: interrupt flag bits are set when an interrupt condition occurs, regardless of the state of its corresponding enable bit or the global enable bit, gie (intcon<7>). 2: user software should ensure the appropri- ate interrupt flag bits are cleared prior to enabling an interrupt and after servicing that interrupt. r/w-0 r/w-0 r-0 r-0 r/w-0 r/w-0 r/w-0 r/w-0 pspif (1) adif rc1if tx1if sspif ccp1if tmr2if tmr1if bit 7 bit 0 bit 7 pspif: parallel slave port read/write interrupt flag bit (1) 1 = a read or a write operation has taken place (must be cleared in software) 0 = no read or write has occurred bit 6 adif: a/d converter interrupt flag bit 1 = an a/d conversion completed (must be cleared in software) 0 = the a/d conversion is not complete bit 5 rc1if: usart1 receive interrupt flag bit 1 = the usart1 receive buffer, rcreg, is full (cleared when rcreg is read) 0 = the usart1 receive buffer is empty bit 4 tx1if: usart transmit interrupt flag bit 1 = the usart1 transmit buffer, txreg, is empty (cleared when txreg is written) 0 = the usart1 transmit buffer is full bit 3 sspif: master synchronous serial port interrupt flag bit 1 = the transmission/reception is complete (must be cleared in software) 0 = waiting to transmit/receive bit 2 ccp1if: ccp1 interrupt flag bit capture mode: 1 = a tmr1 register capture occurred (must be cleared in software) 0 = no tmr1 register capture occurred compare mode: 1 = a tmr1 register compare match occurred (must be cleared in software) 0 = no tmr1 register compare match occurred pwm mode: unused in this mode. bit 1 tmr2if: tmr2 to pr2 match interrupt flag bit 1 = tmr2 to pr2 match occurred (must be cleared in software) 0 = no tmr2 to pr2 match occurred bit 0 tmr1if: tmr1 overflow interrupt flag bit 1 = tmr1 register overflowed (must be cleared in software) 0 = tmr1 register did not overflow note 1: enabled only in microcontroller mode for pic18f8x20 devices. legend: r = readable bit w = writable bit u = unimplemented bit, read as ?0? - n = value at por ?1? = bit is set ?0? = bit is cleared x = bit is unknown
? 2004 microchip technology inc. ds39609b-page 93 pic18f6520/8520/6620/8620/6720/8720 register 9-5: pir2: peripheral interrupt request (flag) register 2 u-0 r/w-0 u-0 r/w-0 r/w-0 r/w-0 r/w-0 r/w-0 ?cmif ? eeif bclif lvdif tmr3if ccp2if bit 7 bit 0 bit 7 unimplemented: read as ? 0 ? bit 6 cmif: comparator interrupt flag bit 1 = the comparator input has changed (must be cleared in software) 0 = the comparator input has not changed bit 5 unimplemented: read as ? 0 ? bit 4 eeif: data eeprom/flash write operation interrupt flag bit 1 = the write operation is complete (must be cleared in software) 0 = the write operation is not complete, or has not been started bit 3 bclif: bus collision interrupt flag bit 1 = a bus collision occurred while the ssp module (configured in i 2 c master mode) was transmitting (must be cleared in software) 0 = no bus collision occurred bit 2 lvdif: low-voltage detect interrupt flag bit 1 = a low-voltage condition occurred (must be cleared in software) 0 = the device voltage is above the low-voltage detect trip point bit 1 tmr3if: tmr3 overflow interrupt flag bit 1 = tmr3 register overflowed (must be cleared in software) 0 = tmr3 register did not overflow bit 0 ccp2if: ccp2 interrupt flag bit capture mode: 1 = a tmr1 or tmr3 register capture occurred (must be cleared in software) 0 = no tmr1 or tmr3 register capture occurred compare mode: 1 = a tmr1 or tmr3 register compare match occurred (must be cleared in software) 0 = no tmr1 or tmr3 register compare match occurred pwm mode: unused in this mode. legend: r = readable bit w = writable bit u = unimplemented bit, read as ?0? - n = value at por ?1? = bit is set ?0? = bit is cleared x = bit is unknown
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 94 ? 2004 microchip technology inc. register 9-6: pir3: peripheral interrupt request (flag) register 3 u-0 u-0 r-0 r-0 r/w-0 r/w-0 r/w-0 r/w-0 ? ? rc2if tx2if tmr4if ccp5if ccp4if ccp3if bit 7 bit 0 bit 7- 6 unimplemented: read as ? 0 ? bit 5 rc2if: usart2 receive interrupt flag bit 1 = the usart2 receive buffer, rcreg, is full (cleared when rcreg is read) 0 = the usart2 receive buffer is empty bit 4 tx2if: usart2 transmit interrupt flag bit 1 = the usart2 transmit buffer, txreg, is empty (cleared when txreg is written) 0 = the usart2 transmit buffer is full bit 3 tmr4if: tmr3 overflow interrupt flag bit 1 = tmr4 register overflowed (must be cleared in software) 0 = tmr4 register did not overflow bit 2-0 ccpxif: ccpx interrupt flag bit (ccp modules 3, 4 and 5) capture mode: 1 = a tmr1 or tmr3 register capture occurred (must be cleared in software) 0 = no tmr1 or tmr3 register capture occurred compare mode: 1 = a tmr1 or tmr3 register compare match occurred (must be cleared in software) 0 = no tmr1 or tmr3 register compare match occurred pwm mode: unused in this mode. legend: r = readable bit w = writable bit u = unimplemented bit, read as ?0? - n = value at por ?1? = bit is set ?0? = bit is cleared x = bit is unknown
? 2004 microchip technology inc. ds39609b-page 95 pic18f6520/8520/6620/8620/6720/8720 9.3 pie registers the pie registers contain the individual enable bits for the peripheral interrupts. due to the number of peripheral interrupt sources, there are three peripheral interrupt enable registers (pie1, pie2 and pie3). when the ipen bit (rcon<7>) is ? 0 ?, the peie bit must be set to enable any of these peripheral interrupts. register 9-7: pie1: peripheral interrupt enable register 1 r/w-0 r/w-0 r/w-0 r/w-0 r/w-0 r/w-0 r/w-0 r/w-0 pspie (1) adie rc1ie tx1ie sspie ccp1ie tmr2ie tmr1ie bit 7 bit 0 bit 7 pspie: parallel slave port read/write interrupt enable bit (1) 1 = enables the psp read/write interrupt 0 = disables the psp read/write interrupt bit 6 adie: a/d converter interrupt enable bit 1 = enables the a/d interrupt 0 = disables the a/d interrupt bit 5 rc1ie: usart1 receive interrupt enable bit 1 = enables the usart1 receive interrupt 0 = disables the usart1 receive interrupt bit 4 tx1ie: usart1 transmit interrupt enable bit 1 = enables the usart1 transmit interrupt 0 = disables the usart1 transmit interrupt bit 3 sspie: master synchronous serial port interrupt enable bit 1 = enables the mssp interrupt 0 = disables the mssp interrupt bit 2 ccp1ie: ccp1 interrupt enable bit 1 = enables the ccp1 interrupt 0 = disables the ccp1 interrupt bit 1 tmr2ie: tmr2 to pr2 match interrupt enable bit 1 = enables the tmr2 to pr2 match interrupt 0 = disables the tmr2 to pr2 match interrupt bit 0 tmr1ie: tmr1 overflow interrupt enable bit 1 = enables the tmr1 overflow interrupt 0 = disables the tmr1 overflow interrupt note 1: enabled only in microcontroller mode for pic18f8x20 devices. legend: r = readable bit w = writable bit u = unimplemented bit, read as ?0? - n = value at por ?1? = bit is set ?0? = bit is cleared x = bit is unknown
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 96 ? 2004 microchip technology inc. register 9-8: pie2: peripheral interrupt enable register 2 u-0 r/w-0 u-0 r/w-0 r/w-0 r/w-0 r/w-0 r/w-0 ?cmie ? eeie bclie lvdie tmr3ie ccp2ie bit 7 bit 0 bit 7 unimplemented: read as ? 0 ? bit 6 cmie: comparator interrupt enable bit 1 = enables the comparator interrupt 0 = disables the comparator interrupt bit 5 unimplemented: read as ? 0 ? bit 4 eeie: data eeprom/flash write operation interrupt enable bit 1 = enables the write operation interrupt 0 = disables the write operation interrupt bit 3 bclie: bus collision interrupt enable bit 1 = enables the bus collision interrupt 0 = disables the bus collision interrupt bit 2 lvdie: low-voltage detect interrupt enable bit 1 = enables the low-voltage detect interrupt 0 = disables the low-voltage detect interrupt bit 1 tmr3ie: tmr3 overflow interrupt enable bit 1 = enables the tmr3 overflow interrupt 0 = disables the tmr3 overflow interrupt bit 0 ccp2ie: ccp2 interrupt enable bit 1 = enables the ccp2 interrupt 0 = disables the ccp2 interrupt legend: r = readable bit w = writable bit u = unimplemented bit, read as ?0? - n = value at por ?1? = bit is set ?0? = bit is cleared x = bit is unknown
? 2004 microchip technology inc. ds39609b-page 97 pic18f6520/8520/6620/8620/6720/8720 register 9-9: pie3: peripheral interrupt enable register 3 u-0 u-0 r/w-0 r/w-0 r/w-0 r/w-0 r/w-0 r/w-0 ? ? rc2ie tx2ie tmr4ie ccp5ie ccp4ie ccp3ie bit 7 bit 0 bit 7-6 unimplemented: read as ? 0 ? bit 5 rc2ie: usart2 receive interrupt enable bit 1 = enables the usart2 receive interrupt 0 = disables the usart2 receive interrupt bit 4 tx2ie: usart2 transmit interrupt enable bit 1 = enables the usart2 transmit interrupt 0 = disables the usart2 transmit interrupt bit 3 tmr4ie: tmr4 to pr4 match interrupt enable bit 1 = enables the tmr4 to pr4 match interrupt 0 = disables the tmr4 to pr4 match interrupt bit 2-0 ccpxie: ccpx interrupt enable bit (ccp modules 3, 4 and 5) 1 = enables the ccpx interrupt 0 = disables the ccpx interrupt legend: r = readable bit w = writable bit u = unimplemented bit, read as ?0? - n = value at por ?1? = bit is set ?0? = bit is cleared x = bit is unknown
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 98 ? 2004 microchip technology inc. 9.4 ipr registers the ipr registers contain the individual priority bits for the peripheral interrupts. due to the number of peripheral interrupt sources, there are three peripheral interrupt priority registers (ipr1, ipr2 and ipr3). the operation of the priority bits requires that the interrupt priority enable (ipen) bit be set. register 9-10: ipr1: peripheral interrupt priority register 1 r/w-1 r/w-1 r/w-1 r/w-1 r/w-1 r/w-1 r/w-1 r/w-1 pspip (1) adip rc1ip tx1ip sspip ccp1ip tmr2ip tmr1ip bit 7 bit 0 bit 7 pspip: parallel slave port read/write interrupt priority bit (1) 1 = high priority 0 = low priority bit 6 adip: a/d converter interrupt priority bit 1 = high priority 0 = low priority bit 5 rc1ip: usart1 receive interrupt priority bit 1 = high priority 0 = low priority bit 4 tx1ip: usart1 transmit interrupt priority bit 1 = high priority 0 = low priority bit 3 sspip: master synchronous serial port interrupt priority bit 1 = high priority 0 = low priority bit 2 ccp1ip: ccp1 interrupt priority bit 1 = high priority 0 = low priority bit 1 tmr2ip: tmr2 to pr2 match interrupt priority bit 1 = high priority 0 = low priority bit 0 tmr1ip: tmr1 overflow interrupt priority bit 1 = high priority 0 = low priority note 1: enabled only in microcontroller mode for pic18f8x20 devices. legend: r = readable bit w = writable bit u = unimplemented bit, read as ?0? - n = value at por ?1? = bit is set ?0? = bit is cleared x = bit is unknown
? 2004 microchip technology inc. ds39609b-page 99 pic18f6520/8520/6620/8620/6720/8720 register 9-11: ipr2: peripheral interrupt priority register 2 u-0 r/w-1 u-0 r/w-1 r/w-1 r/w-1 r/w-1 r/w-1 ?cmip ? eeip bclip lvdip tmr3ip ccp2ip bit 7 bit 0 bit 7 unimplemented: read as ? 0 ? bit 6 cmip: comparator interrupt priority bit 1 = high priority 0 = low priority bit 5 unimplemented: read as ? 0 ? bit 4 eeip: data eeprom/flash write operation interrupt priority bit 1 = high priority 0 = low priority bit 3 bclip: bus collision interrupt priority bit 1 = high priority 0 = low priority bit 2 lvdip: low-voltage detect interrupt priority bit 1 = high priority 0 = low priority bit 1 tmr3ip: tmr3 overflow interrupt priority bit 1 = high priority 0 = low priority bit 0 ccp2ip: ccp2 interrupt priority bit 1 = high priority 0 = low priority legend: r = readable bit w = writable bit u = unimplemented bit, read as ?0? - n = value at por ?1? = bit is set ?0? = bit is cleared x = bit is unknown
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 100 ? 2004 microchip technology inc. register 9-12: ipr3: peripheral interrupt priority register 3 u-0 u-0 r/w-1 r/w-1 r/w-1 r/w-1 r/w-1 r/w-1 ? ? rc2ip tx2ip tmr4ip ccp5ip ccp4ip ccp3ip bit 7 bit 0 bit 7-6 unimplemented: read as ? 0 ? bit 5 rc2ip: usart2 receive interrupt priority bit 1 = high priority 0 = low priority bit 4 tx2ip: usart2 transmit interrupt priority bit 1 = high priority 0 = low priority bit 3 tmr4ip: tmr4 to pr4 match interrupt priority bit 1 = high priority 0 = low priority bit 2-0 ccpxip: ccpx interrupt priority bit (ccp modules 3, 4 and 5) 1 = high priority 0 = low priority legend: r = readable bit w = writable bit u = unimplemented bit, read as ?0? - n = value at por ?1? = bit is set ?0? = bit is cleared x = bit is unknown
? 2004 microchip technology inc. ds39609b-page 101 pic18f6520/8520/6620/8620/6720/8720 9.5 rcon register the rcon register contains the ipen bit, which is used to enable prioritized interrupts. the functions of the other bits in this register are discussed in more detail in section 4.14 ?rcon register? . register 9-13: rcon register r/w-0 u-0 u-0 r/w-1 r-1 r-1 r/w-0 r/w-0 ipen ? ?ri to pd por bor bit 7 bit 0 bit 7 ipen: interrupt priority enable bit 1 = enable priority levels on interrupts 0 = disable priority levels on interrupts (pic16 compatibility mode) bit 6-5 unimplemented: read as ? 0 ? bit 4 ri : reset instruction flag bit for details of bit operation, see register 4-4. bit 3 to : watchdog time-out flag bit for details of bit operation, see register 4-4. bit 2 pd : power-down detection flag bit for details of bit operation, see register 4-4. bit 1 por : power-on reset status bit for details of bit operation, see register 4-4. bit 0 bor : brown-out reset status bit for details of bit operation, see register 4-4. legend: r = readable bit w = writable bit u = unimplemented bit, read as ?0? - n = value at por ?1? = bit is set ?0? = bit is cleared x = bit is unknown
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 102 ? 2004 microchip technology inc. 9.6 int0 interrupt external interrupts on the rb0/int0, rb1/int1, rb2/int2 and rb3/int3 pins are edge-triggered: either rising, if the corresponding intedgx bit is set in the intcon2 register, or falling, if the intedgx bit is clear. when a valid edge appears on the rbx/intx pin, the corresponding flag bit, intxf, is set. this interrupt can be disabled by clearing the corresponding enable bit, intxe. flag bit, intxf, must be cleared in software in the interrupt service routine before re-enabling the interrupt. all external interrupts (int0, int1, int2 and int3) can wake-up the processor from sleep if bit intxie was set prior to going into sleep. if the global interrupt enable bit, gie, is set, the processor will branch to the interrupt vector following wake-up. the interrupt priority for int, int2 and int3 is deter- mined by the value contained in the interrupt priority bits: int1ip (intcon3<6>), int2ip (intcon3<7>) and int3ip (intcon2<1>). there is no priority bit associated with int0; it is always a high priority interrupt source. 9.7 tmr0 interrupt in 8-bit mode (which is the default), an overflow in the tmr0 register (ffh 00h) will set flag bit tmr0if. in 16-bit mode, an overflow in the tmr0h:tmr0l regis- ters (ffffh 0000h) will set flag bit tmr0if. the interrupt can be enabled/disabled by setting/clearing enable bit, tmr0ie (intcon<5>). interrupt priority for timer0 is determined by the value contained in the interrupt priority bit, tmr0ip (intcon2<2>). see section 11.0 ?timer0 module? for further details on the timer0 module. 9.8 portb interrupt-on-change an input change on portb<7:4> sets flag bit, rbif (intcon<0>). the interrupt can be enabled/disabled by setting/clearing enable bit, rbie (intcon<3>). interrupt priority for portb interrupt-on-change is determined by the value contained in the interrupt priority bit, rbip (intcon2<0>). 9.9 context saving during interrupts during an interrupt, the return pc value is saved on the stack. additionally, the wreg, status and bsr registers are saved on the fast return stack. if a fast return from interrupt is not used (see section 4.3 ?fast register stack? ), the user may need to save the wreg, status and bsr registers in software. depending on the user?s application, other registers may also need to be saved. example 9-1 saves and restores the wreg, status and bsr registers during an interrupt service routine. example 9-1: saving status, wreg and bsr registers in ram movwf w_temp ; w_temp is in virtual bank movff status, status_temp ; status_temp located anywhere movff bsr, bsr_temp ; bsr located anywhere ; ; user isr code ; movff bsr_temp, bsr ; restore bsr movf w_temp, w ; restore wreg movff status_temp, status ; restore status
? 2004 microchip technology inc. ds39609b-page 103 pic18f6520/8520/6620/8620/6720/8720 10.0 i/o ports depending on the device selected, there are either seven or nine i/o ports available on pic18fxx20 devices. some of their pins are multiplexed with one or more alternate functions from the other peripheral fea- tures on the device. in general, when a peripheral is enabled, that pin may not be used as a general purpose i/o pin. each port has three registers for its operation. these registers are: tris register (data direction register) port register (reads the levels on the pins of the device) lat register (output latch) the data latch (lat register) is useful for read-modify- write operations on the value that the i/o pins are driving. a simplified version of a generic i/o port and its operation is shown in figure 10-1. figure 10-1: simplified block diagram of port/lat/ tris operation 10.1 porta, trisa and lata registers porta is a 7-bit wide, bidirectional port. the corre- sponding data direction register is trisa. setting a trisa bit (= 1 ) will make the corresponding porta pin an input (i.e., put the corresponding output driver in a high-impedance mode). clearing a trisa bit (= 0 ) will make the corresponding porta pin an output (i.e., put the contents of the output latch on the selected pin). reading the porta register reads the status of the pins, whereas writing to it will write to the port latch. the data latch register (lata) is also memory mapped. read-modify-write operations on the lata register, read and write the latched output value for porta. the ra4 pin is multiplexed with the timer0 module clock input to become the ra4/t0cki pin. the ra4/ t0cki pin is a schmitt trigger input and an open-drain output. all other ra port pins have ttl input levels and full cmos output drivers. the ra6 pin is only enabled as a general i/o pin in ecio and rcio oscillator modes. the other porta pins are multiplexed with analog inputs and the analog v ref + and v ref - inputs. the operation of each pin is selected by clearing/setting the control bits in the adcon1 register (a/d control register 1). the trisa register controls the direction of the ra pins, even when they are being used as analog inputs. the user must ensure the bits in the trisa register are maintained set when using them as analog inputs. example 10-1: initializing porta q d ck wr lat + data latch i/o pin rd port wr port tris rd lat data bus note: on a power-on reset, ra5 and ra3:ra0 are configured as analog inputs and read as ? 0 ?. ra6 and ra4 are configured as digital inputs. clrf porta ; initialize porta by ; clearing output ; data latches clrf lata ; alternate method ; to clear output ; data latches movlw 0x0f ; configure a/d movwf adcon1 ; for digital inputs movlw 0xcf ; value used to ; initialize data ; direction movwf trisa ; set ra<3:0> as inputs ; ra<5:4> as outputs
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 104 ? 2004 microchip technology inc. figure 10-2: block diagram of ra3:ra0 and ra5 pins figure 10-3: block diagram of ra4/t0cki pin figure 10-4: block diagram of ra6 pin (when enabled as i/o) data bus q d q ck q d q ck qd en p n wr lata wr trisa data latch tris latch rd trisa rd porta v ss v dd i/o pin (1) note 1: i/o pins have protection diodes to v dd and v ss . analog input mode ttl input buffer to a/d converter and lvd modules rd lata or porta data bus wr trisa rd porta data latch tris latch schmitt trigger input buffer n v ss i/o pin (1) tmr0 clock input q d q ck q d q ck en qd en rd lata wr lata or porta note 1: i/o pins have protection diodes to v dd and v ss . rd trisa data bus q d q ck qd en p n wr lata wr data latch tris latch rd rd porta v ss v dd i/o pin (1) note 1: i/o pins have protection diodes to v dd and v ss . or porta rd lata ecra6 or ttl input buffer ecra6 or rcra6 enable rcra6 enable trisa q d q ck trisa
? 2004 microchip technology inc. ds39609b-page 105 pic18f6520/8520/6620/8620/6720/8720 table 10-1: porta functions table 10-2: summary of registers associated with porta name bit# buffer function ra0/an0 bit 0 ttl input/output or analog input. ra1/an1 bit 1 ttl input/output or analog input. ra2/an2/v ref - bit 2 ttl input/output or analog input or v ref -. ra3/an3/v ref + bit 3 ttl input/output or analog input or v ref +. ra4/t0cki bit 4 st input/output or external clock input for timer0. output is open-drain type. ra5/an4/lvdin bit 5 ttl input/output or slave select input for synchronous serial port or analog input, or low-voltage detect input. osc2/clko/ra6 bit 6 ttl osc2 or clock output, or i/o pin. legend: ttl = ttl input, st = schmitt trigger input name bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 value on por, bor value on all other resets porta ? ra6 ra5 ra4 ra3 ra2 ra1 ra0 -x0x 0000 -u0u 0000 lata ? lata data output register -xxx xxxx -uuu uuuu trisa ? porta data direction register -111 1111 -111 1111 adcon1 ? ? vcfg1 vcfg0 pcfg3 pcfg2 pcfg1 pcfg0 --00 0000 --00 0000 legend: x = unknown, u = unchanged, ? = unimplemented locations read as ? 0 ?. shaded cells are not used by porta.
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 106 ? 2004 microchip technology inc. 10.2 portb, trisb and latb registers portb is an 8-bit wide, bidirectional port. the corre- sponding data direction register is trisb. setting a trisb bit (= 1 ) will make the corresponding portb pin an input (i.e., put the corresponding output driver in a high-impedance mode). clearing a trisb bit (= 0 ) will make the corresponding portb pin an output (i.e., put the contents of the output latch on the selected pin). the data latch register (latb) is also memory mapped. read-modify-write operations on the latb register, read and write the latched output value for portb. example 10-2: initializing portb each of the portb pins has a weak internal pull-up. a single control bit can turn on all the pull-ups. this is performed by clearing bit rbpu (intcon2<7>). the weak pull-up is automatically turned off when the port pin is configured as an output. the pull-ups are disabled on a power-on reset. four of the portb pins (rb3:rb0) are the external interrupt pins, int3 through int0. in order to use these pins as external interrupts, the corresponding trisb bit must be set to ? 1 ?. the other four portb pins (rb7:rb4) have an inter- rupt-on-change feature. only pins configured as inputs can cause this interrupt to occur (i.e., any rb7:rb4 pin configured as an output is excluded from the interrupt- on-change comparison). the input pins (of rb7:rb4) are compared with the old value latched on the last read of portb. the ?mismatch? outputs of rb7:rb4 are or?ed together to generate the rb port change interrupt with flag bit, rbif (intcon<0>). this interrupt can wake the device from sleep. the user, in the interrupt service routine, can clear the interrupt in the following manner: a) any read or write of portb (except with the movff instruction). this will end the mismatch condition. b) clear flag bit rbif. a mismatch condition will continue to set flag bit, rbif. reading portb will end the mismatch condition and allow flag bit rbif to be cleared. the interrupt-on-change feature is recommended for wake-up on key depression operation and operations where portb is only used for the interrupt-on-change feature. polling of portb is not recommended while using the interrupt-on-change feature. rb3 can be configured by the configuration bit ccp2mx, as the alternate peripheral pin for the ccp2 module. this is only available when the device is configured in microprocessor, microprocessor with boot block, or extended microcontroller operating modes. the rb5 pin is used as the lvp programming pin. when the lvp configuration bit is programmed, this pin loses the i/o function and become a programming test function. figure 10-5: block diagram of rb7:rb4 pins note: on a power-on reset, these pins are configured as digital inputs. clrf portb ; initialize portb by ; clearing output ; data latches clrf latb ; alternate method ; to clear output ; data latches movlw 0xcf ; value used to ; initialize data ; direction movwf trisb ; set rb<3:0> as inputs ; rb<5:4> as outputs ; rb<7:6> as inputs note: when lvp is enabled, the weak pull-up on rb5 is disabled. data latch from other rbpu (2) p v dd i/o pin (1) q d ck q d ck qd en qd en data bus wr latb wr trisb set rbif tris latch rd trisb rd portb rb7:rb4 pins weak pull-up rd portb latch ttl input buffer st buffer rb7:rb5 in serial programming mode q3 q1 rd latb or portb note 1: i/o pins have diode protection to v dd and v ss . 2: to enable weak pull-ups, set the appropriate tris bit(s) and clear the rbpu bit (intcon2<7>).
? 2004 microchip technology inc. ds39609b-page 107 pic18f6520/8520/6620/8620/6720/8720 figure 10-6: block diagram of rb2:rb0 pins figure 10-7: block diagram of rb3 pin data latch rbpu (2) p v dd q d ck q d ck qd en data bus wr port wr tris rd tris rd port weak pull-up rd port intx i/o pin (1) ttl input buffer schmitt trigger buffer tris latch note 1: i/o pins have diode protection to v dd and v ss . 2: to enable weak pull-ups, set the appropriate tris bit(s) and clear the rbpu bit (option_reg<7>). data latch p v dd q d ck q d en data bus wr latb or wr trisb rd trisb rd portb weak pull-up ccp2 or int3 ttl input buffer schmitt trigger buffer tris latch rd latb wr portb rbpu (2) ck d enable (3) ccp output rd portb ccp output (3) 1 0 p n v dd v ss i/o pin (1) q ccp2mx ccp2mx = 0 note 1: i/o pin has diode protection to v dd and v ss . 2: to enable weak pull-ups, set the appropriate tris bit(s) and clear the rbpu bit (intcon2<7>). 3: the ccp2 input/output is multiplexed with rb3 if the ccp2mx bit is enabled (= 0 ) in the configuration register and the device is operating in microprocessor, microprocessor with boot block or extended microcontroller mode.
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 108 ? 2004 microchip technology inc. table 10-3: portb functions table 10-4: summary of registers associated with portb name bit# buffer function rb0/int0 bit 0 ttl/st (1) input/output pin or external interrupt input 0. internal software programmable weak pull-up. rb1/int1 bit 1 ttl/st (1) input/output pin or external interrupt input 1. internal software programmable weak pull-up. rb2/int2 bit 2 ttl/st (1) input/output pin or external interrupt input 2. internal software programmable weak pull-up. rb3/int3/ccp2 (3) bit 3 ttl/st (4) input/output pin or external interrupt input 3. capture2 input/compare2 output/pwm output (when ccp2mx configuration bit is enabled, all pic18f8x20 operating modes except microcontroller mode). internal software programmable weak pull-up. rb4/kbi0 bit 4 ttl input/output pin (with interrupt-on-change). internal software programmable weak pull-up. rb5/kbi1/pgm bit 5 ttl/st (2) input/output pin (with interrupt-on-change). internal software programmable weak pull-up. low-voltage icsp enable pin. rb6/kbi2/pgc bit 6 ttl/st (2) input/output pin (with interrupt-on-change). internal software programmable weak pull-up. serial programming clock. rb7/kbi3/pgd bit 7 ttl/st (2) input/output pin (with interrupt-on-change). internal software programmable weak pull-up. serial programming data. legend: ttl = ttl input, st = schmitt trigger input note 1: this buffer is a schmitt trigger input when configured as the external interrupt. 2: this buffer is a schmitt trigger input when used in serial programming mode. 3: rc1 is the alternate assignment for ccp2 when ccp2mx is not set (all operating modes except microcontroller mode). 4: this buffer is a schmitt trigger input when configured as the ccp2 input. name bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 value on por, bor value on all other resets portb rb7 rb6 rb5 rb4 rb3 rb2 rb1 rb0 xxxx xxxx uuuu uuuu latb latb data output register xxxx xxxx uuuu uuuu trisb portb data direction register 1111 1111 1111 1111 intcon gie/ gieh peie/ giel tmr0ie int0ie rbie tmr0if int0if rbif 0000 0000 0000 0000 intcon2 rbpu intedg0 intedg1 intedg2 intedg3 tmr0ip int3ip rbip 1111 1111 1111 1111 intcon3 int2ip int1ip int3ie int2ie int1ie int3if int2if int1if 1100 0000 1100 0000 legend: x = unknown, u = unchanged. shaded cells are not used by portb.
? 2004 microchip technology inc. ds39609b-page 109 pic18f6520/8520/6620/8620/6720/8720 10.3 portc, trisc and latc registers portc is an 8-bit wide, bidirectional port. the corre- sponding data direction register is trisc. setting a trisc bit (= 1 ) will make the corresponding portc pin an input (i.e., put the corresponding output driver in a high-impedance mode). clearing a trisc bit (= 0 ) will make the corresponding portc pin an output (i.e., put the contents of the output latch on the selected pin). the data latch register (latc) is also memory mapped. read-modify-write operations on the latc register, read and write the latched output value for portc. portc is multiplexed with several peripheral functions (table 10-5). portc pins have schmitt trigger input buffers. when enabling peripheral functions, care should be taken in defining tris bits for each portc pin. some peripherals override the tris bit to make a pin an output, while other peripherals override the tris bit to make a pin an input. the user should refer to the corresponding peripheral section for the correct tris bit settings. the pin override value is not loaded into the tris register. this allows read-modify-write of the tris register, without concern due to peripheral overrides. rc1 is normally configured by configuration bit, ccp2mx, as the default peripheral pin of the ccp2 module (default/erased state, ccp2mx = 1 ). example 10-3: initializing portc figure 10-8: portc block diagram (peripheral output override) note: on a power-on reset, these pins are configured as digital inputs. clrf portc ; initialize portc by ; clearing output ; data latches clrf latc ; alternate method ; to clear output ; data latches movlw 0xcf ; value used to ; initialize data ; direction movwf trisc ; set rc<3:0> as inputs ; rc<5:4> as outputs ; rc<7:6> as inputs portc/peripheral out select data bus wr latc wr trisc data latch tris latch rd trisc q d q ck qd en peripheral data out 0 1 q d q ck p n v dd v ss rd portc peripheral data in i/o pin (1) or wr portc rd latc schmitt trigger note 1: i/o pins have diode protection to v dd and v ss . 2: peripheral output enable is only active if peripheral select is active. tris override peripheral output logic tris override pin override peripheral rc0 yes timer1 osc for timer1/timer3 rc1 yes timer1 osc for timer1/timer3, ccp2 i/o rc2 yes ccp1 i/o rc3 yes spi/i 2 c master clock rc4 yes i 2 c data out rc5 yes spi data out rc6 yes usart1 async xmit, sync clock rc7 yes usart1 sync data out enable (2)
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 110 ? 2004 microchip technology inc. table 10-5: portc functions table 10-6: summary of registers associated with portc name bit# buffer type function rc0/t1oso/t13cki bit 0 st input/output port pin, timer1 oscillator output or timer1/timer3 clock input. rc1/t1osi/ccp2 (1) bit 1 st input/output port pin, timer1 oscillator input or capture2 input/ compare2 output/pwm output (when ccp2mx configuration bit is disabled). rc2/ccp1 bit 2 st input/output port pin or capture1 input/compare1 output/ pwm1 output. rc3/sck/scl bit 3 st rc3 can also be the synchronous serial clock for both spi and i 2 c modes. rc4/sdi/sda bit 4 st rc4 can also be the spi data in (spi mode) or data i/o (i 2 c mode). rc5/sdo bit 5 st input/output port pin or synchronous serial port data output. rc6/tx1/ck1 bit 6 st input/output port pin, addressable usart1 asynchronous transmit or addressable usart1 synchronous clock. rc7/rx1/dt1 bit 7 st input/output port pin, addressable usart1 asynchronous receive or addressable usart1 synchronous data. legend: st = schmitt trigger input note 1: rb3 is the alternate assignment for ccp2 when ccp2mx is set. name bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 value on por, bor value on all other resets portc rc7 rc6 rc5 rc4 rc3 rc2 rc1 rc0 xxxx xxxx uuuu uuuu latc latc data output register xxxx xxxx uuuu uuuu trisc portc data direction register 1111 1111 1111 1111 legend: x = unknown, u = unchanged
? 2004 microchip technology inc. ds39609b-page 111 pic18f6520/8520/6620/8620/6720/8720 10.4 portd, trisd and latd registers portd is an 8-bit wide, bidirectional port. the corre- sponding data direction register is trisd. setting a trisd bit (= 1 ) will make the corresponding portd pin an input (i.e., put the corresponding output driver in a high-impedance mode). clearing a trisd bit (= 0 ) will make the corresponding portd pin an output (i.e., put the contents of the output latch on the selected pin). the data latch register (latd) is also memory mapped. read-modify-write operations on the latd register, read and write the latched output value for portd. portd is an 8-bit port with schmitt trigger input buff- ers. each pin is individually configurable as an input or output. portd is multiplexed with the system bus as the external memory interface; i/o port functions are only available when the system bus is disabled, by setting the ebdis bit in the memcom register (memcon<7>). when operating as the external mem- ory interface, portd is the low-order byte of the multiplexed address/data bus (ad7:ad0). portd can also be configured as an 8-bit wide micro- processor port (parallel slave port) by setting control bit pspmode (trise<4>). in this mode, the input buffers are ttl. see section 10.10 ?parallel slave port? for additional information on the parallel slave port (psp). example 10-4: initializing portd figure 10-9: portd block di agram in i/o port mode note: on a power-on reset, these pins are configured as digital inputs. clrf portd ; initialize portd by ; clearing output ; data latches clrf latd ; alternate method ; to clear output ; data latches movlw 0xcf ; value used to ; initialize data ; direction movwf trisd ; set rd<3:0> as inputs ; rd<5:4> as outputs ; rd<7:6> as inputs data bus wr latd wr trisd data latch tris latch rd trisd i/o pin (1) q d ck q d ck en qd en rd latd or portd 0 1 q q 0 1 p n v dd v ss 0 1 rd portd psp read psp write note 1: i/o pins have diode protection to v dd and v ss . ttl buffer schmitt trigger input buffer portd/ccp1 select pspmode
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 112 ? 2004 microchip technology inc. figure 10-10: portd block diagram in system bus mode instruction register bus enable data/tris out drive bus system bus control data bus wr latd wr trisd rd portd data latch tris latch rd trisd ttl input buffer i/o pin (1) q d ck q d ck en qd en rd latd or portd 0 1 port data instruction read note 1: i/o pins have protection diodes to v dd and v ss .
? 2004 microchip technology inc. ds39609b-page 113 pic18f6520/8520/6620/8620/6720/8720 table 10-7: portd functions table 10-8: summary of registers associated with portd name bit# buffer type function rd0/psp0/ad0 bit 0 st/ttl (1) input/output port pin, parallel slave port bit 0 or address/data bus bit 0. rd1/psp1/ad1 bit 1 st/ttl (1) input/output port pin, parallel slave port bit 1 or address/data bus bit 1. rd2/psp2/ad2 bit 2 st/ttl (1) input/output port pin, parallel slave port bit 2 or address/data bus bit 2. rd3/psp3/ad3 bit 3 st/ttl (1) input/output port pin, parallel slave port bit 3 or address/data bus bit 3. rd4/psp4/ad4 bit 4 st/ttl (1) input/output port pin, parallel slave port bit 4 or address/data bus bit 4. rd5/psp5/ad5 bit 5 st/ttl (1) input/output port pin, parallel slave port bit 5 or address/data bus bit 5. rd6/psp6/ad6 bit 6 st/ttl (1) input/output port pin, parallel slave port bit 6 or address/data bus bit 6. rd7/psp7/ad7 bit 7 st/ttl (1) input/output port pin, parallel slave port bit 7 or address/data bus bit 7. legend: st = schmitt trigger input, ttl = ttl input note 1: input buffers are schmitt triggers when in i/o mode and ttl buffers when in system bus or parallel slave port mode. name bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 value on por, bor value on all other resets portd rd7 rd6 rd5 rd4 rd3 rd2 rd1 rd0 xxxx xxxx uuuu uuuu latd latd data output register xxxx xxxx uuuu uuuu trisd portd data direction register 1111 1111 1111 1111 pspcon ibf obf ibov pspmode ? ? ? ? 0000 ---- 0000 ---- memcon ebdis ? wait1 wait0 ? ? wm1 wm0 0-00 --00 0-00 --00 legend: x = unknown, u = unchanged, ? = unimplemented, read as ? 0 ?. shaded cells are not used by portd.
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 114 ? 2004 microchip technology inc. 10.5 porte, trise and late registers porte is an 8-bit wide, bidirectional port. the corre- sponding data direction register is trise. setting a trise bit (= 1 ) will make the corresponding porte pin an input (i.e., put the corresponding output driver in a high-impedance mode). clearing a trise bit (= 0 ) will make the corresponding porte pin an output (i.e., put the contents of the output latch on the selected pin). read-modify-write operations on the late register, read and write the latched output value for porte. porte is an 8-bit port with schmitt trigger input buff- ers. each pin is individually configurable as an input or output. porte is multiplexed with the ccp module (table 10-9). on pic18f8x20 devices, porte is also multiplexed with the system bus as the external memory interface; the i/o bus is available only when the system bus is disabled, by setting the ebdis bit in the memcon register (memcon<7>). if the device is configured in microprocessor or extended microcontroller mode, then the porte<7:0> becomes the high byte of the address/data bus for the external program memory interface. in microcontroller mode, the porte<2:0> pins become the control inputs for the parallel slave port when bit pspmode (pspcon<4>) is set. (refer to section 4.1.1 ?pic18f8x20 program memory modes? for more information on program memory modes.) when the parallel slave port is active, three porte pins (re0/rd /ad8, re1/wr /ad9 and re2/cs /ad10) function as its control inputs. this automatically occurs when the pspmode bit (pspcon<4>) is set. users must also make certain that bits trise<2:0> are set to configure the pins as digital inputs and the adcon1 register is configured for digital i/o. the porte psp control functions are summarized in table 10-9. pin re7 can be configured as the alternate peripheral pin for ccp module 2 when the device is operating in microcontroller mode. this is done by clearing the configuration bit, ccp2mx, in configuration register, config3h (config3h<0>). example 10-5: initializing porte note: for pic18f8x20 (80-pin) devices operat- ing in extended microcontroller mode, porte defaults to the system bus on power-on reset. clrf porte ; initialize porte by ; clearing output ; data latches clrf late ; alternate method ; to clear output ; data latches movlw 0x03 ; value used to ; initialize data ; direction movwf trise ; set re1:re0 as inputs ; re7:re2 as outputs
? 2004 microchip technology inc. ds39609b-page 115 pic18f6520/8520/6620/8620/6720/8720 figure 10-11: porte block diagram in i/o mode figure 10-12: porte block diagram in system bus mode peripheral out select data bus wr late wr trise data latch tris latch rd trise q d q ck qd en peripheral data out 0 1 q d q ck p n v dd v ss rd porte peripheral data in i/o pin (1) or wr porte rd late schmitt trigger note 1: i/o pins have diode protection to v dd and v ss . tris override peripheral enable tris override pin override peripheral re0 yes external bus re1 yes external bus re2 yes external bus re3 yes external bus re4 yes external bus re5 yes external bus re6 yes external bus re7 yes external bus instruction register bus enable data/tris out drive bus system bus control data bus wr late wr trise rd porte data latch tris latch rd trise ttl input buffer i/o pin (1) q d ck q d ck en qd en rd late or porte 0 1 port data instruction read note 1: i/o pins have protection diodes to v dd and v ss .
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 116 ? 2004 microchip technology inc. table 10-9: porte functions table 10-10: summary of registers associated with porte name bit# buffer type function re0/rd /ad8 bit 0 st/ttl (1) input/output port pin, read control for parallel slave port or address/data bit 8 for rd (psp control mode): 1 = not a read operation 0 = read operation, reads portd register (if chip selected) re1/wr /ad9 bit 1 st/ttl (1) input/output port pin, write control for parallel slave port or address/data bit 9 for wr (psp control mode): 1 = not a write operation 0 = write operation, writes portd register (if chip selected) re2/cs /ad10 bit 2 st/ttl (1) input/output port pin, chip select control for parallel slave port or address/data bit 10 for cs (psp control mode): 1 = device is not selected 0 = device is selected re3/ad11 bit 3 st/ttl (1) input/output port pin or address/data bit 11. re4/ad12 bit 4 st/ttl (1) input/output port pin or address/data bit 12. re5/ad13 bit 5 st/ttl (1) input/output port pin or address/data bit 13. re6/ad14 bit 6 st/ttl (1) input/output port pin or address/data bit 14. re7/ccp2/ad15 bit 7 st/ttl (1) input/output port pin, capture2 input/compare2 output/pwm output (pic18f8x20 devices in microcontroller mode only) or address/data bit 15. legend: st = schmitt trigger input, ttl = ttl input note 1: input buffers are schmitt triggers when in i/o or ccp mode and ttl buffers when in system bus or psp control mode. name bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 value on por, bor value on all other resets trise porte data direction control register 1111 1111 1111 1111 porte read porte pin/write porte data latch xxxx xxxx uuuu uuuu late read porte data latch/write porte data latch xxxx xxxx uuuu uuuu memcon ebdis ? wait1 wait0 ? ? wm1 wm0 0-00 --00 0000 --00 pspcon ibf obf ibov pspmode ? ? ? ? 0000 ---- 0000 ---- legend: x = unknown, u = unchanged. shaded cells are not used by porte.
? 2004 microchip technology inc. ds39609b-page 117 pic18f6520/8520/6620/8620/6720/8720 10.6 portf, latf and trisf registers portf is an 8-bit wide, bidirectional port. the corre- sponding data direction register is trisf. setting a trisf bit (= 1 ) will make the corresponding portf pin an input (i.e., put the corresponding output driver in a high-impedance mode). clearing a trisf bit (= 0 ) will make the corresponding portf pin an output (i.e., put the contents of the output latch on the selected pin). read-modify-write operations on the latf register, read and write the latched output value for portf. portf is multiplexed with several analog peripheral functions, including the a/d converter inputs and comparator inputs, outputs and voltage reference. example 10-6: initializing portf figure 10-13: portf rf1/an6/c2out, rf2/an 7/c1out pins block diagram note 1: on a power-on reset, the rf6:rf0 pins are configured as inputs and read as ? 0 ?. 2: to configure portf as digital i/o, turn off comparators and set adcon1 value. clrf portf ; initialize portf by ; clearing output ; data latches clrf latf ; alternate method ; to clear output ; data latches movlw 0x07 ; movwf cmcon ; turn off comparators movlw 0x0f ; movwf adcon1 ; set portf as digital i/o movlw 0xcf ; value used to ; initialize data ; direction movwf trisf ; set rf3:rf0 as inputs ; rf5:rf4 as outputs ; rf7:rf6 as inputs port/comparator select data bus wr latf wr trisf data latch tris latch rd trisf q d q ck qd en comparator data out 0 1 q d q ck p n v dd v ss rd portf i/o pin or wr portf rd latf schmitt trigger note 1: i/o pins have diode protection to v dd and v ss . analog input mode to a/d converter
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 118 ? 2004 microchip technology inc. figure 10-14: rf6:rf3 and rf0 pins block diagram figure 10-15: rf7 pin block diagram data bus q d q ck q d q ck qd en p n wr latf wr trisf data latch tris latch rd trisf rd portf v ss v dd i/o pin analog input mode st input buffer to a/d converter or comparator input rd latf or wr portf note 1: i/o pins have diode protection to v dd and v ss . data bus wr latf wr trisf rd portf data latch tris latch rd trisf schmitt trigger input buffer i/o pin q d ck q d ck en qd en rd latf or wr portf note: i/o pins have diode protection to v dd and v ss . ttl input buffer ss input
? 2004 microchip technology inc. ds39609b-page 119 pic18f6520/8520/6620/8620/6720/8720 table 10-11: portf functions table 10-12: summary of registers associated with portf name bit# buffer type function rf0/an5 bit 0 st input/output port pin or analog input. rf1/an6/c2out bit 1 st input/output port pin, analog input or comparator 2 output. rf2/an7/c1out bit 2 st input/output port pin, analog input or comparator 1 output. rf3/an8 bit 3 st input/output port pin or analog input/comparator input. rf4/an9 bit 4 st input/output port pin or analog input/comparator input. rf5/an10/cv ref bit 5 st input/output port pin, analog input/comparator input or comparator reference output. rf6/an11 bit 6 st input/output port pin or analog input/comparator input. rf7/ss bit 7 st/ttl input/output port pin or slave select pin for synchronous serial port. legend: st = schmitt trigger input, ttl = ttl input name bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 value on por, bor value on all other resets trisf portf data direction control register 1111 1111 1111 1111 portf read portf pin/write portf data latch xxxx xxxx uuuu uuuu latf read portf data latch/write portf data latch 0000 0000 uuuu uuuu adcon1 ? ? vcfg1 vcfg0 pcfg3 pcfg2 pcfg1 pcfg0 --00 0000 --00 0000 cmcon c2out c1out c2inv c1inv cis cm2 cm1 cm0 0000 0000 0000 0000 cvrcon cvren cvroe cvrr cvrss cvr3 cvr2 cvr1 cvr0 0000 0000 0000 0000 legend: x = unknown, u = unchanged. shaded cells are not used by portf.
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 120 ? 2004 microchip technology inc. 10.7 portg, trisg and latg registers portg is a 5-bit wide, bidirectional port. the corre- sponding data direction register is trisg. setting a trisg bit (= 1 ) will make the corresponding portg pin an input (i.e., put the corresponding output driver in a high-impedance mode). clearing a trisg bit (= 0 ) will make the corresponding portc pin an output (i.e., put the contents of the output latch on the selected pin). the data latch register (latg) is also memory mapped. read-modify-write operations on the latg register, read and write the latched output value for portg. portg is multiplexed with both ccp and usart functions (table 10-13). portg pins have schmitt trigger input buffers. when enabling peripheral functions, care should be taken in defining tris bits for each portg pin. some peripherals override the tris bit to make a pin an output, while other peripherals override the tris bit to make a pin an input. the user should refer to the corresponding peripheral section for the correct tris bit settings. the pin override value is not loaded into the tris reg- ister. this allows read-modify-write of the tris register, without concern due to peripheral overrides. example 10-7: initializing portg figure 10-16: portg block diagram (peripheral output override) note: on a power-on reset, these pins are configured as digital inputs. clrf portg ; initialize portg by ; clearing output ; data latches clrf latg ; alternate method ; to clear output ; data latches movlw 0x04 ; value used to ; initialize data ; direction movwf trisg ; set rg1:rg0 as outputs ; rg2 as input ; rg4:rg3 as inputs portg/peripheral out select data bus wr latg wr trisg data latch tris latch rd trisg q d q ck qd en peripheral data out 0 1 q d q ck p n v dd v ss rd portg peripheral data in i/o pin (1) or wr portg rd latg schmitt trigger note 1: i/o pins have diode protection to v dd and v ss . 2: peripheral output enable is only active if peripheral select is active. tris override peripheral output logic tris override pin override peripheral rg0 yes ccp3 i/o rg1 yes usart1 async xmit, sync clock rg2 yes usart1 async rcv, sync data out rg3 yes ccp4 i/o rg4 yes ccp5 i/o enable (2)
? 2004 microchip technology inc. ds39609b-page 121 pic18f6520/8520/6620/8620/6720/8720 table 10-13: portg functions table 10-14: summary of registers associated with portg name bit# buffer type function rg0/ccp3 bit 0 st input/output port pin or capture3 input/compare3 output/pwm3 output. rg1/tx2/ck2 bit 1 st input/output port pin, addressable usart2 asynchronous transmit or addressable usart2 synchronous clock. rg2/rx2/dt2 bit 2 st input/output port pin, addressable usart2 asynchronous receive or addressable usart2 synchronous data. rg3/ccp4 bit 3 st input/output port pin or capture4 input/compare4 output/pwm4 output. rg4/ccp5 bit 4 st input/output port pin or capture5 input/compare5 output/pwm5 output. legend: st = schmitt trigger input name bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 value on por, bor value on all other resets portg ? ? ? read portf pin/write portf data latch ---x xxxx ---u uuuu latg ? ? ? latg data output register ---x xxxx ---u uuuu trisg ? ? ? data direction control register for portg ---1 1111 ---1 1111 legend: x = unknown, u = unchanged
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 122 ? 2004 microchip technology inc. 10.8 porth, lath and trish registers porth is an 8-bit wide, bidirectional i/o port. the cor- responding data direction register is trish. setting a trish bit (= 1 ) will make the corresponding porth pin an input (i.e., put the corresponding output driver in a high-impedance mode). clearing a trish bit (= 0 ) will make the corresponding porth pin an output (i.e., put the contents of the output latch on the selected pin). read-modify-write operations on the lath register, read and write the latched output value for porth. pins rh7:rh4 are multiplexed with analog inputs an15:an12. pins rh3:rh0 are multiplexed with the system bus as the external memory interface; they are the high-order address bits, a19:a16. by default, pins rh7:rh4 are enabled as a/d inputs and pins rh3:rh0 are enabled as the system address bus. register adcon1 configures rh7:rh4 as i/o or a/d inputs. register memcon configures rh3:rh0 as i/o or system bus pins. example 10-8: initializing porth figure 10-17: rh3:rh0 pins block diagram in i/o mode figure 10-18: rh7:rh4 pins block diagram in i/o mode note: porth is available only on pic18f8x20 devices. note 1: on power-on reset, porth pins rh7:rh4 default to a/d inputs and read as ? 0 ?. 2: on power-on reset, porth pins rh3:rh0 default to system bus signals. clrf porth ; initialize porth by ; clearing output ; data latches clrf lath ; alternate method ; to clear output ; data latches movlw 0fh ; movwf adcon1 ; movlw 0cfh ; value used to ; initialize data ; direction movwf trish ; set rh3:rh0 as inputs ; rh5:rh4 as outputs ; rh7:rh6 as inputs data bus wr lath wr trish rd porth data latch tris latch rd trish schmitt trigger input buffer i/o pin (1) q d ck q d ck en qd en rd lath or porth note 1: i/o pins have diode protection to v dd and v ss . data bus wr lath wr trish rd porth data latch tris latch rd trish schmitt trigger input buffer i/o pin (1) q d ck q d ck en qd en rd lath or porth to a/d converter note 1: i/o pins have diode protection to v dd and v ss .
? 2004 microchip technology inc. ds39609b-page 123 pic18f6520/8520/6620/8620/6720/8720 figure 10-19: rh3:rh0 pins bloc k diagram in system bus mode to instruction register external enable address out drive system system bus control data bus wr lath wr trish rd porth data latch tris latch rd trish ttl input buffer i/o pin (1) q d ck q d ck en qd en rd latd or porth 0 1 port data instruction read note 1: i/o pins have diode protection to v dd and v ss .
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 124 ? 2004 microchip technology inc. table 10-15: porth functions table 10-16: summary of registers associated with porth name bit# buffer type function rh0/a16 bit 0 st/ttl (1) input/output port pin or address bit 16 for external memory interface. rh1/a17 bit 1 st/ttl (1) input/output port pin or address bit 17 for external memory interface. rh2/a18 bit 2 st/ttl (1) input/output port pin or address bit 18 for external memory interface. rh3/a19 bit 3 st/ttl (1) input/output port pin or address bit 19 for external memory interface. rh4/an12 bit 4 st input/output port pin or analog input channel 12. rh5/an13 bit 5 st input/output port pin or analog input channel 13. rh6/an14 bit 6 st input/output port pin or analog input channel 14. rh7/an15 bit 7 st input/output port pin or analog input channel 15. legend: st = schmitt trigger input, ttl = ttl input note 1: input buffers are schmitt triggers when in i/o mode and ttl buffers when in system bus or parallel slave port mode. name bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 value on por, bor value on all other resets trish porth data direction control register 1111 1111 1111 1111 porth read porth pin/write porth data latch xxxx xxxx uuuu uuuu lath read porth data latch/write porth data latch xxxx xxxx uuuu uuuu adcon1 ? ? vcfg1 vcfg0 pcfg3 pcfg2 pcfg1 pcfg0 --00 0000 --00 0000 memcon ebdis ? wait1 wait0 ? ? wm1 wm0 0-00 --00 0-00 --00 legend: x = unknown, u = unchanged, ? = unimplemented. shaded cells are not used by porth.
? 2004 microchip technology inc. ds39609b-page 125 pic18f6520/8520/6620/8620/6720/8720 10.9 portj, trisj and latj registers portj is an 8-bit wide, bidirectional port. the corre- sponding data direction register is trisj. setting a trisj bit (= 1 ) will make the corresponding portj pin an input (i.e., put the corresponding output driver in a high-impedance mode). clearing a trisj bit (= 0 ) will make the corresponding portj pin an output (i.e., put the contents of the output latch on the selected pin). the data latch register (latj) is also memory mapped. read-modify-write operations on the latj register, read and write the latched output value for portj. portj is multiplexed with the system bus as the exter- nal memory interface; i/o port functions are only avail- able when the system bus is disabled. when operating as the external memory interface, portj provides the control signal to external memory devices. the rj5 pin is not multiplexed with any system bus functions. when enabling peripheral functions, care should be taken in defining tris bits for each portj pin. some peripherals override the tris bit to make a pin an output, while other peripherals override the tris bit to make a pin an input. the user should refer to the corre- sponding peripheral section for the correct tris bit settings. the pin override value is not loaded into the tris reg- ister. this allows read-modify-write of the tris register, without concern due to peripheral overrides. example 10-9: initializing portj figure 10-20: portj block diagram in i/o mode note: portj is available only on pic18f8x20 devices. note: on a power-on reset, these pins are configured as digital inputs. clrf portj ; initialize portg by ; clearing output ; data latches clrf latj ; alternate method ; to clear output ; data latches movlw 0xcf ; value used to ; initialize data ; direction movwf trisj ; set rj3:rj0 as inputs ; rj5:rj4 as output ; rj7:rj6 as inputs data bus wr latj wr trisj rd portj data latch tris latch rd trisj schmitt trigger input buffer i/o pin (1) q d ck q d ck en qd en rd latj or portj note 1: i/o pins have diode protection to v dd and v ss .
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 126 ? 2004 microchip technology inc. figure 10-21: rj4:rj0 pins bl ock diagram in system bus mode figure 10-22: rj7:rj6 pins blo ck diagram in system bus mode external enable control out drive system system bus control data bus wr latj wr trisj rd portj data latch tris latch rd trisj i/o pin (1) q d ck q d ck en qd en rd latj or portj 0 1 port data note 1: i/o pins have diode protection to v dd and v ss . wm = 01 ub /lb out drive system system bus control data bus wr latj wr trisj rd portj data latch tris latch rd trisj i/o pin (1) q d ck q d ck en qd en rd latj or portj 0 1 port data note 1: i/o pins have diode protection to v dd and v ss .
? 2004 microchip technology inc. ds39609b-page 127 pic18f6520/8520/6620/8620/6720/8720 table 10-17: portj functions table 10-18: summary of registers associated with portj name bit# buffer type function rj0/ale bit 0 st input/output port pin or address latch enable control for external memory interface. rj1/oe bit 1 st input/output port pin or output enable control for external memory interface. rj2/wrl bit 2 st input/output port pin or write low byte control for external memory interface. rj3/wrh bit 3 st input/output port pin or write high byte control for external memory interface. rj4/ba0 bit 4 st input/output port pin or byte address 0 control for external memory interface. rj5/ce bit 5 st input/output port pin or chip enable control for external memory interface. rj6/lb bit 6 st input/output port pin or lower byte select control for external memory interface. rj7/ub bit 7 st input/output port pin or upper byte select control for external memory interface. legend: st = schmitt trigger input name bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 value on por, bor value on all other resets portj read portj pin/write portj data latch xxxx xxxx uuuu uuuu latj latj data output register xxxx xxxx uuuu uuuu trisj data direction control register for portj 1111 1111 1111 1111 legend: x = unknown, u = unchanged
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 128 ? 2004 microchip technology inc. 10.10 parallel slave port portd also operates as an 8-bit wide parallel slave port, or microprocessor port, when control bit pspmode (pspcon<4>) is set. it is asynchronously readable and writable by the external world through the rd control input pin, re0/rd /ad8 and the wr control input pin, re1/wr /ad9. the psp can directly interface to an 8-bit micro- processor data bus. the external microprocessor can read or write the portd latch as an 8-bit latch. setting bit pspmode enables port pin re0/rd /ad8 to be the rd input, re1/wr /ad9 to be the wr input and re2/ cs /ad10 to be the cs (chip select) input. for this functionality, the corresponding data direction bits of the trise register (trise<2:0>) must be configured as inputs (set). the a/d port configuration bits, pcfg2:pcfg0 (adcon1<2:0>), must be set which will configure pins re2:re0 as digital i/o. a write to the psp occurs when both the cs and wr lines are first detected low. a read from the psp occurs when both the cs and rd lines are first detected low. the porte i/o pins become control inputs for the microprocessor port when bit pspmode (pspcon<4>) is set. in this mode, the user must make sure that the trise<2:0> bits are set (pins are config- ured as digital inputs) and the adcon1 is configured for digital i/o. in this mode, the input buffers are ttl. figure 10-23: portd and porte block diagram (parallel slave port) note: for pic18f8x20 devices, the parallel slave port is available only in microcontroller mode. data bus wr latd rdx q d ck en qd en rd portd pin one bit of portd set interrupt flag pspif (pir1<7>) read chip select write rd cs wr note: i/o pin has protection diodes to v dd and v ss . ttl ttl ttl ttl or portd rd latd data latch tris latch
? 2004 microchip technology inc. ds39609b-page 129 pic18f6520/8520/6620/8620/6720/8720 register 10-1: pspcon register figure 10-24: parallel slave port write waveforms r-0 r-0 r/w-0 r/w-0 u-0 u-0 u-0 u-0 ibf obf ibov pspmode ? ? ? ? bit 7 bit 0 bit 7 ibf: input buffer full status bit 1 = a word has been received and is waiting to be read by the cpu 0 = no word has been received bit 6 obf: output buffer full status bit 1 = the output buffer still holds a previously written word 0 = the output buffer has been read bit 5 ibov: input buffer overflow detect bit 1 = a write occurred when a previously input word has not been read (must be cleared in software) 0 = no overflow occurred bit 4 pspmode: parallel slave port mode select bit 1 = parallel slave port mode 0 = general purpose i/o mode bit 3-0 unimplemented: read as ? 0 ? legend: r = readable bit w = writable bit u = unimplemented bit, read as ?0? - n = value at por ?1? = bit is set ?0? = bit is cleared x = bit is unknown q1 q2 q3 q4 cs q1 q2 q3 q4 q1 q2 q3 q4 wr rd ibf obf pspif portd<7:0>
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 130 ? 2004 microchip technology inc. figure 10-25: parallel slave port read waveforms table 10-19: registers associated with parallel slave port q1 q2 q3 q4 cs q1 q2 q3 q4 q1 q2 q3 q4 wr ibf pspif rd obf portd<7:0> name bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 value on por, bor value on all other resets portd port data latch when written; port pins when read xxxx xxxx uuuu uuuu latd latd data output bits xxxx xxxx uuuu uuuu trisd portd data direction bits 1111 1111 1111 1111 porte ? ? ? ? ? read porte pin/ write porte data latch 0000 0000 0000 0000 late ? ? ? ? ? late data output bits xxxx xxxx uuuu uuuu trise ? ? ? ? ? porte data direction bits 1111 1111 1111 1111 pspcon ibf obf ibov pspmode ? ? ? ? 0000 ---- 0000 ---- intcon gie/ gieh peie/ giel tmr0if int0ie rbie tmr0if int0if rbif 0000 0000 0000 0000 pir1 pspif (1) adif rcif txif sspif ccp1if tmr2if tmr1if 0000 0000 0000 0000 pie1 pspie (1) adie rcie txie sspie ccp1ie tmr2ie tmr1ie 0000 0000 0000 0000 ipr1 pspip (1) adip rcip txip sspip ccp1ip tmr2ip tmr1ip 0111 1111 0111 1111 legend: x = unknown, u = unchanged, ? = unimplemented, read as ? 0 ?. shaded cells are not used by the parallel slave port. note 1: enabled only in microcontroller mode for pic18f8x20 devices.
? 2004 microchip technology inc. ds39609b-page 131 pic18f6520/8520/6620/8620/6720/8720 11.0 timer0 module the timer0 module has the following features: software selectable as an 8-bit or 16-bit timer/counter readable and writable dedicated 8-bit software programmable prescaler clock source selectable to be external or internal interrupt-on-overflow from ffh to 00h in 8-bit mode and ffffh to 0000h in 16-bit mode edge select for external clock figure 11-1 shows a simplified block diagram of the timer0 module in 8-bit mode and figure 11-2 shows a simplified block diagram of the timer0 module in 16-bit mode. the t0con register (register 11-1) is a readable and writable register that controls all the aspects of timer0, including the prescale selection. register 11-1: t0con: timer0 control register r/w-1 r/w-1 r/w-1 r/w-1 r/w-1 r/w-1 r/w-1 r/w-1 tmr0on t08bit t0cs t0se psa t0ps2 t0ps1 t0ps0 bit 7 bit 0 bit 7 tmr0on: timer0 on/off control bit 1 = enables timer0 0 = stops timer0 bit 6 t08bit: timer0 8-bit/16-bit control bit 1 = timer0 is configured as an 8-bit timer/counter 0 = timer0 is configured as a 16-bit timer/counter bit 5 t0cs: timer0 clock source select bit 1 = transition on t0cki pin 0 = internal instruction cycle clock (clko) bit 4 t0se: timer0 source edge select bit 1 = increment on high-to-low transition on t0cki pin 0 = increment on low-to-high transition on t0cki pin bit 3 psa: timer0 prescaler assignment bit 1 = timer0 prescaler is not assigned. timer0 clock input bypasses prescaler. 0 = timer0 prescaler is assigned. timer0 clock input comes from prescaler output. bit 2-0 t0ps2:t0ps0: timer0 prescaler select bits 111 = 1:256 prescale value 110 = 1:128 prescale value 101 = 1:64 prescale value 100 = 1:32 prescale value 011 = 1:16 prescale value 010 = 1:8 prescale value 001 = 1:4 prescale value 000 = 1:2 prescale value legend: r = readable bit w = writable bit u = unimplemented bit, read as ?0? - n = value at por ?1? = bit is set ?0? = bit is cleared x = bit is unknown
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 132 ? 2004 microchip technology inc. figure 11-1: timer0 block diagram in 8-bit mode figure 11-2: timer0 block diagram in 16-bit mode note: upon reset, timer0 is enabled in 8-bit mode with clock input from t0cki max. prescale. ra4/t0cki pin t0se 0 1 0 1 t0cs f osc /4 programmable prescaler sync with internal clocks tmr0 (2 t cy delay) data bus 8 psa t0ps2, t0ps1, t0ps0 set interrupt flag bit tmr0if on overflow 3 note: upon reset, timer0 is enabled in 8-bit mode with clock input from t0cki max. prescale. ra4/t0cki t0se 0 1 0 1 t0cs f osc /4 programmable prescaler sync with internal clocks tmr0l (2 t cy delay) data bus<7:0> 8 psa t0ps2, t0ps1, t0ps0 set interrupt flag bit tmr0if on overflow 3 tmr0 tmr0h high byte 8 8 8 read tmr0l write tmr0l pin
? 2004 microchip technology inc. ds39609b-page 133 pic18f6520/8520/6620/8620/6720/8720 11.1 timer0 operation timer0 can operate as a timer or as a counter. timer mode is selected by clearing the t0cs bit. in timer mode, the timer0 module will increment every instruction cycle (without prescaler). if the tmr0 regis- ter is written, the increment is inhibited for the following two instruction cycles. the user can work around this by writing an adjusted value to the tmr0 register. counter mode is selected by setting the t0cs bit. in counter mode, timer0 will increment, either on every rising or falling edge of pin ra4/t0cki. the increment- ing edge is determined by the timer0 source edge select bit (t0se). clearing the t0se bit selects the rising edge. restrictions on the external clock input are discussed below. when an external clock input is used for timer0, it must meet certain requirements. the requirements ensure the external clock can be synchronized with the internal phase clock (t osc ). also, there is a delay in the actual incrementing of timer0 after synchronization. 11.2 prescaler an 8-bit counter is available as a prescaler for the timer0 module. the prescaler is not readable or writable. the psa and t0ps2:t0ps0 bits determine the prescaler assignment and prescale ratio. clearing bit psa will assign the prescaler to the timer0 module. when the prescaler is assigned to the timer0 module, prescale values of 1:2, 1:4, ..., 1:256 are selectable. when assigned to the timer0 module, all instructions writing to the tmr0 register (e.g., clrf tmr0 , movwf tmr0 , bsf tmr0 , x , ..., etc.) will clear the prescaler count. 11.2.1 switching prescaler assignment the prescaler assignment is fully under software control, (i.e., it can be changed ?on-the-fly? during program execution). 11.3 timer0 interrupt the tmr0 interrupt is generated when the tmr0 register overflows from ffh to 00h in 8-bit mode, or ffffh to 0000h in 16-bit mode. this overflow sets the tmr0if bit. the interrupt can be masked by clearing the tmr0ie bit. the tmr0if bit must be cleared in software by the timer0 module interrupt service routine before re-enabling this interrupt. the tmr0 interrupt cannot awaken the processor from sleep, since the timer is shut-off during sleep. 11.4 16-bit mode timer reads and writes tmr0h is not the high byte of the timer/counter in 16-bit mode, but is actually a buffered version of the high byte of timer0 (refer to figure 11-2). the high byte of the timer0 counter/timer is not directly readable nor writable. tmr0h is updated with the contents of the high byte of timer0 during a read of tmr0l. this pro- vides the ability to read all 16 bits of timer0 without having to verify that the read of the high and low byte were valid, due to a rollover between successive reads of the high and low byte. a write to the high byte of timer0 must also take place through the tmr0h buffer register. timer0 high byte is updated with the contents of tmr0h when a write occurs to tmr0l. this allows all 16 bits of timer0 to be updated at once. table 11-1: registers associated with timer0 note: writing to tmr0 when the prescaler is assigned to timer0, will clear the prescaler count, but will not change the prescaler assignment. name bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 value on por, bor value on all other resets tmr0l timer0 module low byte register xxxx xxxx uuuu uuuu tmr0h timer0 module high byte register 0000 0000 0000 0000 intcon gie/gieh peie/giel tmr0ie int0ie rbie tmr0if int0if rbif 0000 0000 0000 0000 t0con tmr0on t08bit t0cs t0se psa t0ps2 t0ps1 t0ps0 1111 1111 1111 1111 trisa ? porta data direction register -111 1111 -111 1111 legend: x = unknown, u = unchanged, ? = unimplemented locations, read as ? 0 ?. shaded cells are not used by timer0.
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 134 ? 2004 microchip technology inc. notes:
? 2004 microchip technology inc. ds39609b-page 135 pic18f6520/8520/6620/8620/6720/8720 12.0 timer1 module the timer1 module timer/counter has the following features: 16-bit timer/counter (two 8-bit registers: tmr1h and tmr1l) readable and writable (both registers) internal or external clock select interrupt-on-overflow from ffffh to 0000h reset from ccp module special event trigger figure 12-1 is a simplified block diagram of the timer1 module. register 12-1 details the timer1 control register. this register controls the operating mode of the timer1 module and contains the timer1 oscillator enable bit (t1oscen). timer1 can be enabled or disabled by setting or clearing control bit, tmr1on (t1con<0>). timer1 can also be used to provide real-time clock (rtc) functionality to applications, with only a minimal addition of external components and code overhead. register 12-1: t1con: timer1 control register r/w-0 u-0 r/w-0 r/w-0 r/w-0 r/w-0 r/w-0 r/w-0 rd16 ? t1ckps1 t1c kps0 t1oscen t1sync tmr1cs tmr1on bit 7 bit 0 bit 7 rd16: 16-bit read/write mode enable bit 1 = enables register read/write of timer1 in one 16-bit operation 0 = enables register read/write of timer1 in two 8-bit operations bit 6 unimplemented: read as ? 0 ? bit 5-4 t1ckps1:t1ckps0 : timer1 input clock prescale select bits 11 = 1:8 prescale value 10 = 1:4 prescale value 01 = 1:2 prescale value 00 = 1:1 prescale value bit 3 t1oscen: timer1 oscillator enable bit 1 = timer1 oscillator is enabled 0 = timer1 oscillator is shut off the oscillator inverter and feedback resistor are turned off to eliminate power drain. bit 2 t1sync : timer1 external clock input synchronization select bit when tmr1cs = 1 : 1 = do not synchronize external clock input 0 = synchronize external clock input when tmr1cs = 0 : this bit is ignored. timer1 uses the internal clock when tmr1cs = 0 . bit 1 tmr1cs: timer1 clock source select bit 1 = external clock from pin rc0/t1oso/t13cki (on the rising edge) 0 = internal clock (f osc /4) bit 0 tmr1on: timer1 on bit 1 = enables timer1 0 = stops timer1 legend: r = readable bit w = writable bit u = unimplemented bit, read as ?0? - n = value at por ?1? = bit is set ?0? = bit is cleared x = bit is unknown
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 136 ? 2004 microchip technology inc. 12.1 timer1 operation timer1 can operate in one of these modes: as a timer as a synchronous counter as an asynchronous counter the operating mode is determined by the clock select bit, tmr1cs (t1con<1>). when tmr1cs = 0 , timer1 increments every instruc- tion cycle. when tmr1cs = 1 , timer1 increments on every rising edge of the external clock input or the timer1 oscillator, if enabled. when the timer1 oscillator is enabled (t1oscen is set), the rc1/t1osi and rc0/t1oso/t13cki pins become inputs. that is, the trisc<1:0> value is ignored and the pins are read as ? 0 ?. timer1 also has an internal ?reset input?. this reset can be generated by the ccp module (see section 16.0 ?capture/compare/pwm (ccp) modules? ). figure 12-1: timer1 block diagram figure 12-2: timer1 block diag ram: 16-bit read/write mode tmr1h tmr1l t1sync tmr1cs t1ckps1:t1ckps0 sleep input f osc /4 internal clock tmr1on on/off prescaler 1, 2, 4, 8 synchronize det 1 0 0 1 synchronized clock input 2 tmr1if overflow tmr1 clr ccp special event trigger t1oscen enable oscillator (1) t1osc interrupt flag bit note 1: when enable bit t1oscen is cleared, the inverter and feedback re sistor are turned off. this eliminates power drain. t1osi t1oso/t13cki timer 1 tmr1l t1osc t1sync tmr1cs t1ckps1:t1ckps0 sleep input t1oscen enable oscillator (1) tmr1if overflow interrupt f osc /4 internal clock tmr1on on/off prescaler 1, 2, 4, 8 synchronize det 1 0 0 1 synchronized clock input 2 t1oso/t13cki t1osi tmr1 flag bit note 1: when enable bit t1oscen is cleared, the inverter and feedback re sistor are turned off. this eliminates power drain. high byte data bus<7:0> 8 tmr1h 8 8 8 read tmr1l write tmr1l clr ccp special event trigger
? 2004 microchip technology inc. ds39609b-page 137 pic18f6520/8520/6620/8620/6720/8720 12.2 timer1 oscillator a crystal oscillator circuit is built-in between pins t1osi (input) and t1oso (amplifier output). it is enabled by setting control bit, t1oscen (t1con<3>). the oscil- lator is a low-power oscillator, rated up to 200 khz. it will continue to run during sleep. it is primarily intended for a 32 khz crystal. the circuit for a typical lp oscilla- tor is shown in figure 12-3. table 12-1 shows the capacitor selection for the timer1 oscillator. the user must provide a software time delay to ensure proper start-up of the timer1 oscillator figure 12-3: external components for the timer1 lp oscillator 12.2.1 low-power timer1 option (pic18fx520 devices only) the timer1 oscillator for pic18lfx520 devices incor- porates a low-power feature, which allows the oscillator to automatically reduce its power consumption when the microcontroller is in sleep mode. as high noise environments may cause excessive oscillator instability in sleep mode, this option is best suited for low noise applications where power conservation is an important design consideration. due to the low-power nature of the oscillator, it may also be sensitive to rapidly changing signals in close proximity. the oscillator circuit, shown in figure 12-3, should be located as close as possible to the microcontroller. there should be no circuits passing within the oscillator circuit boundaries other than v ss or v dd . if a high-speed circuit must be located near the oscilla- tor (such as the ccp1 pin in output compare or pwm mode, or the primary oscillator using the osc2 pin), a grounded guard ring around the oscillator circuit, as shown in figure 12-4, may be helpful when used on a single-sided pcb or in addition to a ground plane. figure 12-4: oscillator circuit with grounded guard ring table 12-1: capacitor selection for the alternate oscillator osc type freq c1 c2 lp 32 khz tbd (1) tbd (1) crystal to be tested: 32.768 khz epson c-001r32.768k-a 20 ppm note 1: microchip suggests 33 pf as a starting point in validating the oscillator circuit. 2: higher capacitance increases the stability of the oscillator, but also increases the start-up time. 3: since each resonator/crystal has its own characteristics, the user should consult the resonator/crystal manufacturer for appropriate values of external components. 4: capacitor values are for design guidance only. note: see the notes with table 12-1 for additiona l information about capacitor selection. c1 c2 xtal pic18fxx20 t1osi t1oso 32.768 khz 33 pf 33 pf note: pic18fx620/x720 devices have the standard timer1 oscillator permanently selected. pic18lfx620/x720 devices have the low-power timer1 oscillator permanently selected. v dd osc1 v ss osc2 rc0 rc1 rc2 note: not drawn to scale.
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 138 ? 2004 microchip technology inc. 12.3 timer1 interrupt the tmr1 register pair (tmr1h:tmr1l) increments from 0000h to ffffh and rolls over to 0000h. the tmr1 interrupt, if enabled, is generated on overflow, which is latched in interrupt flag bit, tmr1if (pir1<0>). this interrupt can be enabled/disabled by setting/clearing tmr1 interrupt enable bit, tmr1ie (pie1<0>). 12.4 resetting timer1 using a ccp trigger output if the ccp module is configured in compare mode to generate a ?special event trigger? (ccp1m3:ccp1m0 = 1011 ), this signal will reset timer1 and start an a/d conversion (if the a/d module is enabled). timer1 must be configured for either timer or synchro- nized counter mode to take advantage of this feature. if timer1 is running in asynchronous counter mode, this reset operation may not work. in the event that a write to timer1 coincides with a special event trigger from ccp1, the write will take precedence. in this mode of operation, the ccpr1h:ccpr1l register pair effectively becomes the period register for timer1. 12.5 timer1 16-bit read/write mode timer1 can be configured for 16-bit reads and writes (see figure 12-2). when the rd16 control bit (t1con<7>) is set, the address for tmr1h is mapped to a buffer register for the high byte of timer1. a read from tmr1l will load the contents of the high byte of timer1 into the timer1 high byte buffer. this provides the user with the ability to accurately read all 16 bits of timer1 without having to determine whether a read of the high byte, followed by a read of the low byte, is valid, due to a rollover between reads. a write to the high byte of timer1 must also take place through the tmr1h buffer register. timer1 high byte is updated with the contents of tmr1h when a write occurs to tmr1l. this allows a user to write all 16 bits to both the high and low bytes of timer1 at once. the high byte of timer1 is not directly readable or writ- able in this mode. all reads and writes must take place through the timer1 high byte buffer register. writes to tmr1h do not clear the timer1 prescaler. the prescaler is only cleared on writes to tmr1l. 12.6 using timer1 as a real-time clock adding an external lp oscillator to timer1 (such as the one described in section 12.2 ?timer1 oscillator? ) gives users the option to include rtc functionality to their applications. this is accomplished with an inex- pensive watch crystal to provide an accurate time base and several lines of application code to calculate the time. when operating in sleep mode and using a battery or supercapacitor as a power source, it can completely eliminate the need for a separate rtc device and battery backup. the application code routine, rtcisr , shown in example 12-1, demonstrates a simple method to incre- ment a counter at one-second intervals using an interrupt service routine. incrementing the tmr1 register pair to overflow, triggers the interrupt and calls the routine, which increments the seconds counter by one; additional counters for minutes and hours are incremented as the previous counter overflow. since the register pair is 16 bits wide, counting up to overflow the register directly from a 32.768 khz clock would take 2 seconds. to force the overflow at the required one-second intervals, it is necessary to preload it; the simplest method is to set the msb of tmr1h with a bsf instruction. note that the tmr1l register is never preloaded or altered; doing so may introduce cumulative error over many cycles. for this method to be accurate, timer1 must operate in asynchronous mode and the timer1 overflow interrupt must be enabled (pie1<0> = 1 ), as shown in the routine, rtcinit . the timer1 oscillator must also be enabled and running at all times. note: the special event triggers from the ccp1 module will not set interrupt flag bit tmr1if (pir1<0>).
? 2004 microchip technology inc. ds39609b-page 139 pic18f6520/8520/6620/8620/6720/8720 example 12-1: implementing a real-time clock using a timer1 interrupt service table 12-2: registers associated with timer1 as a timer/counter rtcinit movlw 0x80 ; preload tmr1 register pair movwf tmr1h ; for 1 second overflow clrf tmr1l movlw b?00001111? ; configure for external clock, movwf t1osc ; asynchronous operation, external oscillator clrf secs ; initialize timekeeping registers clrf mins ; movlw .12 movwf hours bsf pie1, tmr1ie ; enable timer1 interrupt return rtcisr bsf tmr1h, 7 ; preload for 1 sec overflow bcf pir1, tmr1if ; clear interrupt flag incf secs, f ; increment seconds movlw .59 ; 60 seconds elapsed? cpfsgt secs return ; no, done clrf secs ; clear seconds incf mins, f ; increment minutes movlw .59 ; 60 minutes elapsed? cpfsgt mins return ; no, done clrf mins ; clear minutes incf hours, f ; increment hours movlw .23 ; 24 hours elapsed? cpfsgt hours return ; no, done movlw .01 ; reset hours to 1 movwf hours return ; done name bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 value on por, bor value on all other resets intcon gie/gieh peie/giel tmr0ie int0ie rbie tmr0if int0if rbif 0000 0000 0000 0000 pir1 pspif adif rcif txif sspif ccp1if tmr2if tmr1if 0000 0000 0000 0000 pie1 pspie adie rcie txie sspie ccp1ie tmr2ie tmr1ie 0000 0000 0000 0000 ipr1 pspip adip rcip txip sspip ccp1ip tmr2ip tmr1ip 0111 1111 0111 1111 tmr1l holding register for the least significant byte of the 16-bit tmr1 register xxxx xxxx uuuu uuuu tmr1h holding register for the most significant byte of the 16-bit tmr1 register xxxx xxxx uuuu uuuu t1con rd16 ? t1ckps1 t1ckps0 t1oscen t1sync tmr1cs tmr1on 0-00 0000 u-uu uuuu legend: x = unknown, u = unchanged, ? = unimplemented, read as ? 0 ?. shaded cells are not used by the timer1 module.
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 140 ? 2004 microchip technology inc. notes:
? 2004 microchip technology inc. ds39609b-page 141 pic18f6520/8520/6620/8620/6720/8720 13.0 timer2 module the timer2 module timer has the following features: 8-bit timer (tmr2 register) 8-bit period register (pr2) readable and writable (both registers) software programmable prescaler (1:1, 1:4, 1:16) software programmable postscaler (1:1 to 1:16) interrupt on tmr2 match of pr2 ssp module optional use of tmr2 output to generate clock shift timer2 has a control register shown in register 13-1. timer2 can be shut-off by clearing control bit, tmr2on (t2con<2>), to minimize power consumption. figure 13-1 is a simplified block diagram of the timer2 module. register 13-1 shows the timer2 control regis- ter. the prescaler and postscaler selection of timer2 are controlled by this register. 13.1 timer2 operation timer2 can be used as the pwm time base for the pwm mode of the ccp module. the tmr2 register is readable and writable and is cleared on any device reset. the input clock (f osc /4) has a prescale option of 1:1, 1:4 or 1:16, selected by control bits, t2ckps1:t2ckps0 (t2con<1:0>). the match out- put of tmr2 goes through a 4-bit postscaler (which gives a 1:1 to 1:16 scaling inclusive) to generate a tmr2 interrupt (latched in flag bit, tmr2if (pir1<1>)). the prescaler and postscaler counters are cleared when any of the following occurs: a write to the tmr2 register a write to the t2con register any device reset (power-on reset, mclr reset, watchdog timer reset or brown-out reset) tmr2 is not cleared when t2con is written. register 13-1: t2con: time r2 control register u-0 r/w-0 r/w-0 r/w-0 r/w-0 r/w-0 r/w-0 r/w-0 ? t2outps3 t2outps2 t2outps1 t2outps0 tmr2on t2ckps1 t2ckps0 bit 7 bit 0 bit 7 unimplemented: read as ? 0 ? bit 6-3 t2outps3:t2outps0: timer2 output postscale select bits 0000 = 1:1 postscale 0001 = 1:2 postscale 1111 = 1:16 postscale bit 2 tmr2on: timer2 on bit 1 = timer2 is on 0 = timer2 is off bit 1-0 t2ckps1:t2ckps0: timer2 clock prescale select bits 00 = prescaler is 1 01 = prescaler is 4 1x = prescaler is 16 legend: r = readable bit w = writable bit u = unimplemented bit, read as ?0? - n = value at por ?1? = bit is set ?0? = bit is cleared x = bit is unknown
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 142 ? 2004 microchip technology inc. 13.2 timer2 interrupt the timer2 module has an 8-bit period register, pr2. timer2 increments from 00h until it matches pr2 and then resets to 00h on the next increment cycle. pr2 is a readable and writable register. the pr2 register is initialized to ffh upon reset. 13.3 output of tmr2 the output of tmr2 (before the postscaler) is fed to the synchronous serial port module, which optionally uses it to generate the shift clock. figure 13-1: timer2 block diagram table 13-1: registers associated with timer2 as a timer/counter name bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 value on por, bor value on all other resets intcon gie/gieh peie/giel tmr0ie int0ie rbie tmr0if int0if rbif 0000 0000 0000 0000 pir1 pspif adif rcif txif sspif ccp1if tmr2if tmr1if 0000 0000 0000 0000 pie1 pspie adie rcie txie sspie ccp1ie tmr2ie tmr1ie 0000 0000 0000 0000 ipr1 pspip adip rcip txip sspip ccp1ip tmr2ip tmr1ip 0111 1111 0111 1111 tmr2 timer2 module register 0000 0000 0000 0000 t2con ? t2outps3 t2outps2 t2outps1 t2outps0 tmr2on t2ckps1 t2ckps0 -000 0000 -000 0000 pr2 timer2 period register 1111 1111 1111 1111 legend: x = unknown, u = unchanged, ? = unimplemented, read as ? 0 ?. shaded cells are not used by the timer2 module. comparator tmr2 sets flag tmr2 output (1) reset postscaler prescaler pr2 2 f osc /4 1:1 to 1:16 1:1, 1:4, 1:16 eq 4 bit tmr2if note 1: tmr2 register output can be software se lected by the ssp module as a baud clock. t2outps3:t2outps0 t2ckps1:t2ckps0
? 2004 microchip technology inc. ds39609b-page 143 pic18f6520/8520/6620/8620/6720/8720 14.0 timer3 module the timer3 module timer/counter has the following features: 16-bit timer/counter (two 8-bit registers; tmr3h and tmr3l) readable and writable (both registers) internal or external clock select interrupt-on-overflow from ffffh to 0000h reset from ccp module trigger figure 14-1 is a simplified block diagram of the timer3 module. register 14-1 shows the timer3 control register. this register controls the operating mode of the timer3 module and sets the ccp clock source. register 12-1 shows the timer1 control register. this register controls the operating mode of the timer1 module, as well as contains the timer1 oscillator enable bit (t1oscen), which can be a clock source for timer3. register 14-1: t3con: time r3 control register r/w-0 r/w-0 r/w-0 r/w-0 r/w-0 r/w-0 r/w-0 r/w-0 rd16 t3ccp2 t3ckps1 t3ckps0 t3ccp1 t3sync tmr3cs tmr3on bit 7 bit 0 bit 7 rd16: 16-bit read/write mode enable bit 1 = enables register read/write of timer3 in one 16-bit operation 0 = enables register read/write of timer3 in two 8-bit operations bit 6, 3 t3ccp2:t3ccp1: timer3 and timer1 to ccpx enable bits 11 = timer3 and timer4 are the clock sources for ccp1 through ccp5 10 = timer3 and timer4 are the clock sources for ccp3 through ccp5; timer1 and timer2 are the clock sources for ccp1 and ccp2 01 = timer3 and timer4 are the clock sources for ccp2 through ccp5; timer1 and timer2 are the clock sources for ccp1 00 = timer1 and timer2 are the clock sources for ccp1 through ccp5 bit 5-4 t3ckps1:t3ckps0: timer3 input clock prescale select bits 11 = 1:8 prescale value 10 = 1:4 prescale value 01 = 1:2 prescale value 00 = 1:1 prescale value bit 2 t3sync : timer3 external clock input synchronization control bit (not usable if the system clock comes from timer1/timer3.) when tmr3cs = 1 : 1 = do not synchronize external clock input 0 = synchronize external clock input when tmr3cs = 0 : this bit is ignored. timer3 uses the internal clock when tmr3cs = 0 . bit 1 tmr3cs: timer3 clock source select bit 1 = external clock input from timer1 oscillator or t13cki (on the rising edge after the first falling edge) 0 = internal clock (f osc /4) bit 0 tmr3on: timer3 on bit 1 = enables timer3 0 = stops timer3 legend: r = readable bit w = writable bit u = unimplemented bit, read as ?0? - n = value at por ?1? = bit is set ?0? = bit is cleared x = bit is unknown
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 144 ? 2004 microchip technology inc. 14.1 timer3 operation timer3 can operate in one of these modes: as a timer as a synchronous counter as an asynchronous counter the operating mode is determined by the clock select bit, tmr3cs (t3con<1>). when tmr3cs = 0 , timer3 increments every instruc- tion cycle. when tmr3cs = 1 , timer3 increments on every rising edge of the timer1 external clock input or the timer1 oscillator, if enabled. when the timer1 oscillator is enabled (t1oscen is set), the rc1/t1osi and rc0/t1oso/t13cki pins become inputs. that is, the trisc<1:0> value is ignored and the pins are read as ? 0 ?. timer3 also has an internal ?reset input?. this reset can be generated by the ccp module (see section 14.0 ?timer3 module? ). figure 14-1: timer3 block diagram figure 14-2: timer3 block diagram co nfigured in 16-bit read/write mode tmr3h tmr3l t1osc t3sync tmr3cs t3ckps1:t3ckps0 sleep input t1oscen enable oscillator (1) tmr3if overflow interrupt f osc /4 internal clock tmr3on on/off prescaler 1, 2, 4, 8 synchronize det 1 0 0 1 synchronized clock input 2 t1oso/ t1osi flag bit (3) note 1: when enable bit t1oscen is cleared, the inverter and feedback resistor are turned off. th is eliminates power drain. t13cki clr ccp special trigger t3ccpx timer3 tmr3l t1osc t3sync tmr3cs t3ckps1:t3ckps0 sleep input t1oscen enable oscillator (1) f osc /4 internal clock tmr3on on/off prescaler 1, 2, 4, 8 synchronize det 1 0 0 1 synchronized clock input 2 t1oso/ t1osi tmr3 t13cki clr ccp special trigger t3ccpx to timer1 clock input note 1: when the t1oscen bit is cleared, the inverter and feedback re sistor are turned off. this eliminates power drain. high byte data bus<7:0> 8 tmr3h 8 8 8 read tmr3l write tmr3l set tmr3if flag bit on overflow
? 2004 microchip technology inc. ds39609b-page 145 pic18f6520/8520/6620/8620/6720/8720 14.2 timer1 oscillator the timer1 oscillator may be used as the clock source for timer3. the timer1 oscillator is enabled by setting the t1oscen (t1con<3>) bit. the oscillator is a low- power oscillator rated up to 200 khz. see section 12.0 ?timer1 module? for further details. 14.3 timer3 interrupt the tmr3 register pair (tmr3h:tmr3l) increments from 0000h to ffffh and rolls over to 0000h. the tmr3 interrupt, if enabled, is generated on overflow, which is latched in interrupt flag bit, tmr3if (pir2<1>). this interrupt can be enabled/disabled by setting/clearing tmr3 interrupt enable bit, tmr3ie (pie2<1>). 14.4 resetting timer3 using a ccp trigger output if the ccp module is configured in compare mode to generate a ?special event trigger? (ccp1m3:ccp1m0 = 1011 ), this signal will reset timer3. timer3 must be configured for either timer or synchro- nized counter mode to take advantage of this feature. if timer3 is running in asynchronous counter mode, this reset operation may not work. in the event that a write to timer3 coincides with a special event trigger from ccp1, the write will take precedence. in this mode of operation, the ccpr1h:ccpr1l register pair effectively becomes the period register for timer3. table 14-1: registers associated with timer3 as a timer/counter note: the special event triggers from the ccp module will not set interrupt flag bit, tmr3if (pir1<0>). name bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 value on por, bor value on all other resets intcon gie/gieh peie/giel tmr0ie int0ie rbie tmr0if int0if rbif 0000 0000 0000 0000 pir2 ? ? ? eeif bclif lvdif tmr3if ccp2if ---0 0000 ---0 0000 pie2 ? ? ? eeie bclie lvdie tmr3ie ccp2ie ---0 0000 ---0 0000 ipr2 ? ? ? eeip bclip lvdip tmr3ip ccp2ip ---1 1111 ---1 1111 tmr3l holding register for the least significant byte of the 16-bit tmr3 register xxxx xxxx uuuu uuuu tmr3h holding register for the most significant byte of the 16-bit tmr3 register xxxx xxxx uuuu uuuu t1con rd16 ? t1ckps1 t1ckps0 t1oscen t1sync tmr1cs tmr1on 0-00 0000 u-uu uuuu t3con rd16 t3ccp2 t3ckps1 t3ckps0 t3ccp1 t3sync tmr3cs tmr3on 0000 0000 uuuu uuuu legend: x = unknown, u = unchanged, ? = unimplemented, read as ? 0 ?. shaded cells are not used by the timer3 module.
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 146 ? 2004 microchip technology inc. notes:
? 2004 microchip technology inc. ds39609b-page 147 pic18f6520/8520/6620/8620/6720/8720 15.0 timer4 module the timer4 module timer has the following features: 8-bit timer (tmr4 register) 8-bit period register (pr4) readable and writable (both registers) software programmable prescaler (1:1, 1:4, 1:16) software programmable postscaler (1:1 to 1:16) interrupt on tmr4 match of pr4 timer4 has a control register shown in register 15-1. timer4 can be shut-off by clearing control bit, tmr4on (t4con<2>), to minimize power consumption. the prescaler and postscaler selection of timer4 are also controlled by this register. figure 15-1 is a simplified block diagram of the timer4 module. 15.1 timer4 operation timer4 can be used as the pwm time base for the pwm mode of the ccp module. the tmr4 register is readable and writable and is cleared on any device reset. the input clock (f osc /4) has a prescale option of 1:1, 1:4 or 1:16, selected by control bits t4ckps1:t4ckps0 (t4con<1:0>). the match out- put of tmr4 goes through a 4-bit postscaler (which gives a 1:1 to 1:16 scaling inclusive) to generate a tmr4 interrupt, latched in flag bit, tmr4if (pir3<3>). the prescaler and postscaler counters are cleared when any of the following occurs: a write to the tmr4 register a write to the t4con register any device reset (power-on reset, mclr reset, watchdog timer reset or brown-out reset) tmr4 is not cleared when t4con is written. register 15-1: t4con: time r4 control register u-0 r/w-0 r/w-0 r/w-0 r/w-0 r/w-0 r/w-0 r/w-0 ? t4outps3 t4outps2 t4outps1 t4outps0 tmr4on t4ckps1 t4ckps0 bit 7 bit 0 bit 7 unimplemented: read as ? 0 ? bit 6-3 t4outps3:t4outps0: timer4 output postscale select bits 0000 = 1:1 postscale 0001 = 1:2 postscale 1111 = 1:16 postscale bit 2 tmr4on: timer4 on bit 1 = timer4 is on 0 = timer4 is off bit 1-0 t4ckps1:t4ckps0: timer4 clock prescale select bits 00 = prescaler is 1 01 = prescaler is 4 1x = prescaler is 16 legend: r = readable bit w = writable bit u = unimplemented bit, read as ?0? - n = value at por ?1? = bit is set ?0? = bit is cleared x = bit is unknown
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 148 ? 2004 microchip technology inc. 15.2 timer4 interrupt the timer4 module has an 8-bit period register, pr4, which is both readable and writable. timer4 increments from 00h until it matches pr4 and then resets to 00h on the next increment cycle. the pr4 register is initialized to ffh upon reset. 15.3 output of tmr4 the output of tmr4 (before the postscaler) is used only as a pwm time base for the ccp modules. it is not used as a baud rate clock for the mssp, as is the timer2 output. figure 15-1: timer4 block diagram table 15-1: registers associated with timer4 as a timer/counter name bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 value on por, bor value on all other resets intcon gie/gieh peie/giel tmr0ie int0ie rbie tmr0if int0if rbif 0000 0000 0000 0000 ipr3 ? ? rc2ip tx2ip tmr4ip ccp5ip ccp4ip ccp3ip --11 1111 --00 0000 pir3 ? ? rc2if tx2if tmr4if ccp5if ccp4if ccp3if --00 0000 --00 0000 pie3 ? ? rc2ie tx2ie tmr4ie ccp5ie ccp4ie ccp3ie --00 0000 --00 0000 tmr4 timer4 module register 0000 0000 0000 0000 t4con ? t4outps3 t4outps2 t4outps1 t4outps0 tmr4on t4ckps1 t4ckps0 -000 0000 -000 0000 pr4 timer4 period register 1111 1111 1111 1111 legend: x = unknown, u = unchanged, ? = unimplemented, read as ? 0 ?. shaded cells are not used by the timer4 module. comparator tmr4 sets flag tmr4 output (1) reset postscaler prescaler pr4 2 f osc /4 1:1 to 1:16 1:1, 1:4, 1:16 eq 4 bit tmr4if t4outps3:t4outps0 t4ckps1:t4ckps0
? 2004 microchip technology inc. ds39609b-page 149 pic18f6520/8520/6620/8620/6720/8720 16.0 capture/compare/pwm (ccp) modules the pic18fxx20 devices all have five ccp (capture/ compare/pwm) modules. each module contains a 16-bit register, which can operate as a 16-bit capture register, a 16-bit compare register or a pulse width modulation (pwm) master/slave duty cycle register. table 16-1 shows the timer resources of the ccp module modes. the operation of all ccp modules are identical, with the exception of the special event trigger present on ccp1 and ccp2. for the sake of clarity, ccp module operation in the following sections is described with respect to ccp1. the descriptions can be applied (with the exception of the special event triggers) to any of the modules. register 16-1: ccpxcon register note: throughout this section, references to register and bit names that may be associ- ated with a specific ccp module are referred to generically by the use of ?x? or ?y? in place of the specific module number. thus, ?ccpxcon? might refer to the control register for ccp1, ccp2, ccp3, ccp4 or ccp5. u-0 u-0 r/w-0 r/w-0 r/w-0 r/w-0 r/w-0 r/w-0 ? ? dcxb1 dcxb0 ccpxm3 ccpxm2 ccpxm1 ccpxm0 bit 7 bit 0 bit 7-6 unimplemented: read as ? 0 ? bit 5-4 dcxb1:dcxb0: pwm duty cycle bit 1 and bit 0 for ccp module x capture mode: unused. compare mode: unused. pwm mode: these bits are the two least significant bits (bit 1 and bit 0) of the 10-bit pwm duty cycle. the eight most significant bits (dcx9:dcx2) of the duty cycle are found in ccprxl. bit 3-0 ccpxm3:ccpxm0: ccp module x mode select bits 0000 = capture/compare/pwm disabled (resets ccpx module) 0001 = reserved 0010 = compare mode, toggle output on match (ccpxif bit is set) 0011 = reserved 0100 = capture mode, every falling edge 0101 = capture mode, every rising edge 0110 = capture mode, every 4th rising edge 0111 = capture mode, every 16th rising edge 1000 = compare mode, initialize ccp pin low; on compare match, force ccp pin high (ccpif bit is set) 1001 = compare mode, initialize ccp pin high; on compare match, force ccp pin low (ccpif bit is set) 1010 = compare mode, generate software interrupt on compare match (ccpif bit is set, (ccp pin is unaffected) 1011 = compare mode, trigger special event (ccpif bit is set): for ccp1 and ccp2: timer1 or timer3 is reset on event. for all other modules: ccpx pin is unaffected and is configured as an i/o port (same as ccpxm<3:0> = 1010 , above). 11xx =pwm mode legend: r = readable bit w = writable bit u = unimplemented bit, read as ?0? - n = value at por ?1? = bit is set ?0? = bit is cleared x = bit is unknown
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 150 ? 2004 microchip technology inc. 16.1 ccp module configuration each capture/compare/pwm module is associated with a control register (generically, ccpxcon) and a data register (ccprx). the data register, in turn, is comprised of two 8-bit registers: ccprxl (low byte) and ccprxh (high byte). all registers are both readable and writable. 16.1.1 ccp modules and timer resources the ccp modules utilize timers 1, 2, 3 or 4, depending on the mode selected. timer1 and timer3 are available to modules in capture or compare modes, while timer2 and timer4 are available for modules in pwm mode. table 16-1: ccp mode ? timer resource the assignment of a particular timer to a module is determined by the timer-to-ccp enable bits in the t3con register (register 14-1). depending on the configuration selected, up to four timers may be active at once, with modules in the same configuration (capture/compare or pwm) sharing timer resources. the possible configurations are shown in figure 16-1. figure 16-1: ccp and timer interconnect configurations ccp mode timer resource capture compare pwm timer1 or timer3 timer1 or timer3 timer2 or timer4 tmr1 ccp5 tmr2 tmr3 tmr4 ccp4 ccp3 ccp2 ccp1 tmr1 tmr2 tmr3 ccp5 tmr4 ccp4 ccp3 ccp2 ccp1 tmr1 tmr2 tmr3 ccp5 tmr4 ccp4 ccp3 ccp2 ccp1 tmr1 tmr2 tmr3 ccp5 tmr4 ccp4 ccp3 ccp2 ccp1 t3ccp<2:1> = 00 t3ccp<2:1> = 01 t3ccp<2:1> = 10 t3ccp<2:1> = 11 timer1 is used for all capture and compare operations for all ccp modules. timer2 is used for pwm operations for all ccp modules. modules may share either timer resource as a common time base. timer3 and timer4 are not available. timer1 and timer2 are used for capture and compare or pwm operations for ccp1 only (depending on selected mode). all other modules use either timer3 or timer4. modules may share either timer resource as a common time base, if they are in capture/ compare or pwm modes. timer1 and timer2 are used for capture and compare or pwm operations for ccp1 and ccp2 only (depending on the mode selected for each module). both modules may use a timer as a common time base if they are both in capture/compare or pwm modes. the other modules use either timer3 or timer4. modules may share either timer resource as a common time base if they are in capture/ compare or pwm modes. timer3 is used for all capture and compare operations for all ccp modules. timer4 is used for pwm operations for all ccp modules. modules may share either timer resource as a common time base. timer1 and timer2 are no t available.
? 2004 microchip technology inc. ds39609b-page 151 pic18f6520/8520/6620/8620/6720/8720 16.2 capture mode in capture mode, ccpr1h:ccpr1l captures the 16-bit value of the tmr1 or tmr3 registers when an event occurs on pin rc2/ccp1. an event is defined as one of the following: every falling edge every rising edge every 4th rising edge every 16th rising edge the event is selected by control bits, ccp1m3:ccp1m0 (ccp1con<3:0>). when a capture is made, the inter- rupt request flag bit, ccp1if (pir1<2>), is set; it must be cleared in software. if anot her capture occurs before the value in register ccpr1 is read, the old captured value is overwritten by the new captured value. 16.2.1 ccp pin configuration in capture mode, the rc2/ccp1 pin should be configured as an input by setting the trisc<2> bit. 16.2.2 timer1/timer3 mode selection the timers that are to be used with the capture feature (timer1 and/or timer3) must be running in timer mode, or synchronized counter mode. in asynchronous counter mode, the capture operation may not work. the timer to be used with each ccp module is selected in the t3con register (see section 16.1.1 ?ccp modules and timer resources? ). 16.2.3 software interrupt when the capture mode is changed, a false capture interrupt may be generated. the user should keep bit ccp1ie (pie1<2>) clear to avoid false interrupts and should clear the flag bit, ccp1if, following any such change in operating mode. 16.2.4 ccp prescaler there are four prescaler settings, specified by bits ccp1m3:ccp1m0. whenever the ccp module is turned off or the ccp module is not in capture mode, the prescaler counter is cleared. this means that any reset will clear the prescaler counter. switching from one capture prescaler to another may generate an interrupt. also, the prescaler counter will not be cleared, therefore, the first capture may be from a non-zero prescaler. example 16-1 shows the recommended method for switching between capture prescalers. this example also clears the prescaler counter and will not generate the ?false? interrupt. example 16-1: changing between capture prescalers figure 16-2: capture mode operat ion block diagram note: if the rc2/ccp1 is configured as an out- put, a write to the port can cause a capture condition. clrf ccp1con, f ; turn ccp module off movlw new_capt_ps ; load wreg with the ; new prescaler mode ; value and ccp on movwf ccp1con ; load ccp1con with ; this value ccpr1h ccpr1l tmr1h tmr1l set flag bit ccp1if tmr3 enable q?s ccp1con<3:0> ccp1 pin prescaler 1, 4, 16 and edge detect tmr3h tmr3l tmr1 enable t3ccp2 t3ccp2
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 152 ? 2004 microchip technology inc. 16.3 compare mode in compare mode, the 16-bit ccpr1 register value is constantly compared against either the tmr1 register pair value or the tmr3 register pair value. when a match occurs, the ccp1 pin: is driven high is driven low toggles output (high-to-low or low-to-high) remains unchanged the action on the pin is based on the value of control bits, ccp1m3:ccp1m0. at the same time, interrupt flag bit ccp1if (ccp2if) is set. 16.3.1 ccp pin configuration the user must configure the ccpx pin as an output by clearing the appropriate tris bit. 16.3.2 timer1/timer3 mode selection timer1 and/or timer3 must be running in timer mode, or synchronized counter mode, if the ccp module is using the compare feature. in asynchronous counter mode, the compare operation may not work. 16.3.3 software interrupt mode when generate software interrupt is chosen, the ccp1 pin is not affected. only a ccp interrupt is generated (if enabled). 16.3.4 special event trigger in this mode, an internal hardware trigger is generated, which may be used to initiate an action. the special event trigger output of either ccp1 or ccp2, resets the tmr1 or tmr3 register pair, depend- ing on which timer resource is currently selected. this allows the ccpr1 register to effectively be a 16-bit programmable period register for timer1 or timer3. the ccp2 special event trigger will also start an a/d conversion if the a/d module is enabled. figure 16-3: compare mode operation block diagram note: clearing the ccp1con register will force the rc2/ccp1 compare output latch to the default low level. this is not the portc i/o data latch. note: the special event trigger from the ccp2 module will not set the timer1 or timer3 interrupt flag bits. ccpr1h ccpr1l tmr1h tmr1l comparator qs r output logic special event trigger set flag bit ccp1if match rc2/ccp1 pin trisc<2> ccp1con<3:0> mode select output enable for ccp1 and ccp2 only, the special event trigger will: reset timer1 or timer3, but not set timer1 or timer3 interrupt flag bit and set bit go/done (adcon0<2>), which starts an a/d conversion (ccp2 only) tmr3h tmr3l t3ccp2 1 0
? 2004 microchip technology inc. ds39609b-page 153 pic18f6520/8520/6620/8620/6720/8720 table 16-2: registers associated with capture, compare, timer1 and timer3 name bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 value on por, bor value on all other resets intcon gie/gieh peie/giel tmr0ie int0ie rbie tmr0if int0if rbif 0000 0000 0000 0000 rcon ipen ? ? ri to pd por bor 0--1 11qq 0--q qquu pir1 pspif adif rcif txif sspif ccp1if tmr2if tmr1if 0000 0000 0000 0000 pie1 pspie adie rcie txie sspie ccp1ie tmr2ie tmr1ie 0000 0000 0000 0000 ipr1 pspip adip rcip txip sspip ccp1ip tmr2ip tmr1ip 0111 1111 0111 1111 pir2 ? cmie ? eeie bclif lvdif tmr3if ccp2if -0-0 0000 ---0 0000 pie2 ? cmif ? eeif bclie lvdie tmr3ie ccp2ie -0-0 0000 ---0 0000 ipr2 ? cmip ? eeip bclip lvdip tmr3ip ccp2ip -1-1 1111 ---1 1111 pir3 ? ? rc2if tx2if tmr4if ccp5if ccp4if ccp3if --00 0000 --00 0000 pie3 ? ? rc2ie tx2ie tmr4ie ccp5ie ccp4ie ccp3ie --00 0000 --00 0000 ipr3 ? ? rc2ip tx2ip tmr4ip ccp5ip ccp4ip ccp3ip --11 1111 --11 1111 trisc portc data direction register 1111 1111 1111 1111 tmr1l holding register for the least significant byte of the 16-bit tmr1 register xxxx xxxx uuuu uuuu tmr1h holding register for the most significant byte of the 16-bit tmr1 register xxxx xxxx uuuu uuuu t1con rd16 ? t1ckps1 t1ckps0 t1oscen t1sync tmr1cs tmr1on 0-00 0000 u-uu uuuu tmr3h timer3 register high byte xxxx xxxx uuuu uuuu tmr3l timer3 register low byte xxxx xxxx uuuu uuuu t3con rd16 t3ccp2 t3ckps1 t3ckps0 t3ccp1 t3sync tmr3cs tmr3on 0000 0000 uuuu uuuu ccprxl (1) capture/compare/pwm register x (lsb) xxxx xxxx uuuu uuuu ccprxh (1) capture/compare/pwm register x (msb) xxxx xxxx uuuu uuuu ccpxcon (1) ? ? dcxb1 dcxb0 ccpxm3 ccpxm2 ccpxm1 ccpxm0 --00 0000 --00 0000 legend: x = unknown, u = unchanged, ? = unimplemented, read as ? 0 ? . shaded cells are not used by capture and compare, timer1 or timer3. note 1: generic term for all of the identical registers of this name for all ccp modules, where ?x? identifies the individual module (ccp1 through ccp5). bit assignments and reset values for all registers of the same generic name are identical.
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 154 ? 2004 microchip technology inc. 16.4 pwm mode in pulse width modulation (pwm) mode, the ccp1 pin produces up to a 10-bit resolution pwm output. since the ccp1 pin is multiplexed with the portc data latch, the trisc<2> bit must be cleared to make the ccp1 pin an output. figure 16-4 shows a simplified block diagram of the ccp module in pwm mode. for a step-by-step procedure on how to set up the ccp module for pwm operation, see section 16.4.3 ?setup for pwm operation? . figure 16-4: simplified pwm block diagram a pwm output (figure 16-5) has a time base (period) and a time that the output stays high (duty cycle). the frequency of the pwm is the inverse of the period (1/period). figure 16-5: pwm output 16.4.1 pwm period the pwm period is specified by writing to the pr2 register. the pwm period can be calculated using the following formula: equation 16-1: pwm frequency is defined as 1/[pwm period]. when tmr2 is equal to pr2, the following three events occur on the next increment cycle: tmr2 is cleared the ccp1 pin is set (exception: if pwm duty cycle = 0%, the ccp1 pin will not be set) the pwm duty cycle is latched from ccpr1l into ccpr1h 16.4.2 pwm duty cycle the pwm duty cycle is specified by writing to the ccpr1l register and to the ccp1con<5:4> bits. up to 10-bit resolution is available. the ccpr1l contains the eight msbs and the ccp1con<5:4> contains the two lsbs. this 10-bit value is represented by ccpr1l:ccp1con<5:4>. the following equation is used to calculate the pwm duty cycle in time: equation 16-2: ccpr1l and ccp1con<5:4> can be written to at any time, but the duty cycle value is not latched into ccpr1h until after a match between pr2 and tmr2 occurs (i.e., the period is complete). in pwm mode, ccpr1h is a read-only register. the ccpr1h register and a 2-bit internal latch are used to double-buffer the pwm duty cycle. this doublebuffering is essential for glitchless pwm operation. when the ccpr1h and 2-bit latch match tmr2, con- catenated with an internal 2-bit q clock or 2 bits of the tmr2 prescaler, the ccp1 pin is cleared. note: clearing the ccp1con register will force the ccp1 pwm output latch to the default low level. this is not the portc i/o data latch. ccpr1l ccpr1h (slave) comparator tmr2 comparator pr2 (note 1) r q s duty cycle registers ccp1con<5:4> clear timer, ccp1 pin and latch d.c. trisc<2> rc2/ccp1 note 1: 8-bit timer is concatenated with 2-bit internal q clock or 2 bits of the prescaler to create 10-bit time base. period duty cycle tmr2 = pr2 tmr2 = duty cycle tmr2 = pr2 note: the timer2 and timer4 postscalers (see section 13.0 ?timer2 module? ) are not used in the determination of the pwm frequency. the postscaler could be used to have a servo update rate at a different frequency than the pwm output. pwm period = (pr2) + 1] 4 t osc (tmr2 prescale value) pwm duty cycle = (ccpr1l:ccp1con<5:4>) t osc (tmr2 prescale value)
? 2004 microchip technology inc. ds39609b-page 155 pic18f6520/8520/6620/8620/6720/8720 the maximum pwm resolution (bits) for a given pwm frequency is given by the equation: equation 16-3: 16.4.3 setup for pwm operation the following steps should be taken when configuring the ccp module for pwm operation: 1. set the pwm period by writing to the pr2 register. 2. set the pwm duty cycle by writing to the ccpr1l register and ccp1con<5:4> bits. 3. make the ccp1 pin an output by clearing the trisc<2> bit. 4. set the tmr2 prescale value and enable timer2 by writing to t2con. 5. configure the ccp1 module for pwm operation. table 16-3: example pwm frequencies and resolutions at 40 mhz table 16-4: registers associated with pwm, timer2 and timer4 note: if the pwm duty cycle value is longer than the pwm period, the ccp1 pin will not be cleared. f osc f pwm --------------- ?? ?? log 2 () log ----------------------------- b i t s = pwm resolution (max) pwm frequency 2.44 khz 9.77 khz 39.06 khz 156.25 khz 312.50 khz 416.67 khz timer prescaler (1, 4, 16)1641111 pr2 value ffh ffh ffh 3fh 1fh 17h maximum resolution (bits) 14 10 12 10 10 8 7 6.58 name bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 value on por, bor value on all other resets intcon gie/gieh peie/giel tmr0ie int0ie rbie tmr0if int0if rbif 0000 0000 0000 0000 rcon ipen ? ? ri to pd por bor 0--1 11qq 0--q qquu pir1 pspif adif rcif txif sspif ccp1if tmr2if tmr1if 0000 0000 0000 0000 pie1 pspie adie rcie txie sspie ccp1ie tmr2ie tmr1ie 0000 0000 0000 0000 ipr1 pspip adip rcip txip sspip ccp1ip tmr2ip tmr1ip 0111 1111 0111 1111 pir2 ? cmie ? eeie bclif lvdif tmr3if ccp2if -0-0 0000 ---0 0000 pie2 ? cmif ? eeif bclie lvdie tmr3ie ccp2ie -0-0 0000 ---0 0000 ipr2 ? cmip ? eeip bclip lvdip tmr3ip ccp2ip -1-1 1111 ---1 1111 pir3 ? ? rc2if tx2if tmr4if ccp5if ccp4if ccp3if --00 0000 --00 0000 pie3 ? ? rc2ie tx2ie tmr4ie ccp5ie ccp4ie ccp3ie --00 0000 --00 0000 ipr3 ? ? rc2ip tx2ip tmr4ip ccp5ip ccp4ip ccp3ip --11 1111 --11 1111 tmr2 timer2 module register 0000 0000 0000 0000 pr2 timer2 module period register 1111 1111 1111 1111 t2con ? t2outps3 t2outps2 t2outps1 t2outps0 tmr2on t2ckps1 t2ckps0 -000 0000 -000 0000 t3con rd16 t3ccp2 t3ckps1 t3ckps0 t3ccp1 t3sync tmr3cs tmr3on 0000 0000 uuuu uuuu tmr4 timer4 register 0000 0000 uuuu uuuu pr4 timer4 period register 1111 1111 uuuu uuuu t4con ? t4outps3 t4outps2 t4outps1 t4outps0 tmr4on t4ckps1 t4ckps0 -000 0000 uuuu uuuu ccprxl (1) capture/compare/pwm register x (lsb) xxxx xxxx uuuu uuuu ccprxh (1) capture/compare/pwm register x (msb) xxxx xxxx uuuu uuuu ccpxcon (1) ? ? dcxb1 dcxb0 ccpxm3 ccpxm2 ccpxm1 ccpxm0 --00 0000 --00 0000 legend: x = unknown, u = unchanged, ? = unimplemented, read as ? 0 ? . shaded cells are not used by pwm, timer2, or timer4. note 1: generic term for all of the identical registers of this name for all ccp modules, where ?x? identifies the individual module (ccp1 through ccp5). bit assignments and reset values for all registers of the same generic name are identical.
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 156 ? 2004 microchip technology inc. notes:
? 2004 microchip technology inc. ds39609b-page 157 pic18f6520/8520/6620/8620/6720/8720 17.0 master synchronous serial port (mssp) module 17.1 master ssp (mssp) module overview the master synchronous serial port (mssp) module is a serial interface, useful for communicating with other peripheral or microcontroller devices. these peripheral devices may be serial eeproms, shift registers, dis- play drivers, a/d converters, etc. the mssp module can operate in one of two modes: serial peripheral interface (spi) inter-integrated circuit (i 2 c) - full master mode - slave mode (with general address call) the i 2 c interface supports the following modes in hardware: master mode multi-master mode slave mode 17.2 control registers the mssp module has three associated registers. these include a status register (sspstat) and two control registers (sspcon1 and sspcon2). the use of these registers and their individual configuration bits differ significantly, depending on whether the mssp module is operated in spi or i 2 c mode. additional details are provided under the individual sections. 17.3 spi mode the spi mode allows 8 bits of data to be synchronously transmitted and received simultaneously. all four modes of spi are supported. to accomplish communication, typically three pins are used: serial data out (sdo) ? rc5/sdo serial data in (sdi) ? rc4/sdi/sda serial clock (sck) ? rc3/sck/scl additionally, a fourth pin may be used when in a slave mode of operation: slave select (ss ) ? rf7/ss figure 17-1 shows the block diagram of the mssp module when operating in spi mode. figure 17-1: mssp block diagram (spi mode) ( ) read write internal data bus sspsr reg sspm3:sspm0 bit0 shift clock ss control enable edge select clock select tmr2 output t osc prescaler 4, 16, 64 2 edge select 2 4 data to tx/rx in sspsr tris bit 2 smp:cke rc5/sdo sspbuf reg rc4/sdi/sda rf7/ss rc3/sck/ scl
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 158 ? 2004 microchip technology inc. 17.3.1 registers the mssp module has four registers for spi mode operation. these are: mssp control register 1 (sspcon1) mssp status register (sspstat) serial receive/transmit buffer (sspbuf) mssp shift register (sspsr) ? not directly accessible sspcon1 and sspstat are the control and status registers in spi mode operation. the sspcon1 regis- ter is readable and writable. the lower 6 bits of the sspstat are read-only. the upper two bits of the sspstat are read/write. sspsr is the shift register used for shifting data in or out. sspbuf is the buffer register to which data bytes are written to or read from. in receive operations, sspsr and sspbuf together create a double-buffered receiver. when sspsr receives a complete byte, it is transferred to sspbuf and the sspif interrupt is set. during transmission, the sspbuf is not double- buffered. a write to sspbuf will write to both sspbuf and sspsr. register 17-1: sspstat: mssp status register (spi mode) r/w-0 r/w-0 r-0 r-0 r-0 r-0 r-0 r-0 smp cke d/a psr/w ua bf bit 7 bit 0 bit 7 smp: sample bit spi master mode: 1 = input data sampled at end of data output time 0 = input data sampled at middle of data output time spi slave mode: smp must be cleared when spi is used in slave mode. bit 6 cke: spi clock select bit 1 = transmit occurs on transition from active to idle clock state 0 = transmit occurs on transition from idle to active clock state note: polarity of clock state is set by the ckp bit (sspcon1<4>). bit 5 d/a : data/address bit used in i 2 c mode only. bit 4 p: stop bit used in i 2 c mode only. this bit is cleared when the mssp module is disabled, sspen is cleared. bit 3 s: start bit used in i 2 c mode only. bit 2 r/w : read/write bit information used in i 2 c mode only. bit 1 ua: update address bit used in i 2 c mode only. bit 0 bf: buffer full status bit (receive mode only) 1 = receive complete, sspbuf is full 0 = receive not complete, sspbuf is empty legend: r = readable bit w = writable bit u = unimplemented bit, read as ?0? - n = value at por ?1? = bit is set ?0? = bit is cleared x = bit is unknown
? 2004 microchip technology inc. ds39609b-page 159 pic18f6520/8520/6620/8620/6720/8720 register 17-2: sspcon1: mssp control register1 (spi mode) r/w-0 r/w-0 r/w-0 r/w-0 r/w-0 r/w-0 r/w-0 r/w-0 wcol sspov sspen ckp sspm3 sspm2 sspm1 sspm0 bit 7 bit 0 bit 7 wcol: write collision detect bit (transmit mode only) 1 = the sspbuf register is written while it is still transmitting the previous word (must be cleared in software) 0 = no collision bit 6 sspov: receive overflow indicator bit spi slave mode: 1 = a new byte is received while the sspbuf register is still holding the previous data. in case of overflow, the data in sspsr is lost. overflow can only occur in slave mode. the user must read the sspbuf, even if only transmitting data, to avoid setting overflow (must be cleared in software). 0 = no overflow note: in master mode, the overflow bit is not set, since each new reception (and transmission) is initiated by writing to the sspbuf register. bit 5 sspen: synchronous serial port enable bit 1 = enables serial port and configures sck, sdo, sdi and ss as serial port pins 0 = disables serial port and configures these pins as i/o port pins note: when enabled, these pins must be properly configured as input or output. bit 4 ckp: clock polarity select bit 1 = idle state for clock is a high level 0 = idle state for clock is a low level bit 3-0 sspm3:sspm0: synchronous serial port mode select bits 0101 = spi slave mode, clock = sck pin, ss pin control disabled, ss can be used as i/o pin 0100 = spi slave mode, clock = sck pin, ss pin control enabled 0011 = spi master mode, clock = tmr2 output/2 0010 = spi master mode, clock = f osc /64 0001 = spi master mode, clock = f osc /16 0000 = spi master mode, clock = f osc /4 note: bit combinations not specifically listed here are either reserved, or implemented in i 2 c mode only. legend: r = readable bit w = writable bit u = unimplemented bit, read as ?0? - n = value at por ?1? = bit is set ?0? = bit is cleared x = bit is unknown
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 160 ? 2004 microchip technology inc. 17.3.2 operation when initializing the spi, several options need to be specified. this is done by programming the appropriate control bits (sspcon1<5:0> and sspstat<7:6>). these control bits allow the following to be specified: master mode (sck is the clock output) slave mode (sck is the clock input) clock polarity (idle state of sck) data input sample phase (middle or end of data output time) clock edge (output data on rising/falling edge of sck) clock rate (master mode only) slave select mode (slave mode only) the mssp consists of a transmit/receive shift regis- ter (sspsr) and a buffer register (sspbuf). the sspsr shifts the data in and out of the device, msb first. the sspbuf holds the data that was written to the sspsr until the received data is ready. once the 8 bits of data have been received, that byte is moved to the sspbuf register. then, the buffer full detect bit, bf (sspstat<0>) and the interrupt flag bit, sspif, are set. this double-buffering of the received data (sspbuf) allows the next byte to start reception before reading the data that was just received. any write to the sspbuf register during transmission/reception of data will be ignored and the write collision detect bit, wcol (sspcon1<7>), will be set. user software must clear the wcol bit so that it can be determined if the follow- ing write(s) to the sspbuf register completed successfully. when the application software is expecting to receive valid data, the sspbuf should be read before the next byte of data to transfer is written to the sspbuf. buffer full bit, bf (sspstat<0>), indicates when sspbuf has been loaded with the received data (transmission is complete). when the sspbuf is read, the bf bit is cleared. this data may be irrelevant if the spi is only a transmitter. generally, the mssp interrupt is used to determine when the transmission/reception has com- pleted. the sspbuf must be read and/or written. if the interrupt method is not going to be used, then software polling can be done to ensure that a write collision does not occur. example 17-1 shows the loading of the sspbuf (sspsr) for data transmission. the sspsr is not directly readable or writable and can only be accessed by addressing the sspbuf register. additionally, the mssp status register (sspstat) indicates the various status conditions. equation 17-1: loading the sspbuf (sspsr) register loop btfss sspstat, bf ;has data been received (transmit complete)? bra loop ;no movf sspbuf, w ;wreg reg = contents of sspbuf movwf rxdata ;save in user ram, if data is meaningful movf txdata, w ;w reg = contents of txdata movwf sspbuf ;new data to transmit
? 2004 microchip technology inc. ds39609b-page 161 pic18f6520/8520/6620/8620/6720/8720 17.3.3 enabling spi i/o to enable the serial port, ssp enable bit, sspen (sspcon1<5>), must be set. to reset or reconfigure spi mode, clear the sspen bit, reinitialize the sspcon registers and then set the sspen bit. this configures the sdi, sdo, sck and ss pins as serial port pins. for the pins to behave as the serial port func- tion, some must have their data direction bits (in the tris register) appropriately programmed as follows: sdi is automatically controlled by the spi module sdo must have trisc<5> bit cleared sck (master mode) must have trisc<3> bit cleared sck (slave mode) must have trisc<3> bit set ss must have trisf<7> bit set any serial port function that is not desired may be overridden by programming the corresponding data direction (tris) register to the opposite value. 17.3.4 typical connection figure 17-2 shows a typical connection between two microcontrollers. the master controller (processor 1) initiates the data transfer by sending the sck signal. data is shifted out of both shift registers on their pro- grammed clock edge and latched on the opposite edge of the clock. both processors should be programmed to the same clock polarity (ckp), then both controllers would send and receive data at the same time. whether the data is meaningful (or dummy data) depends on the application software. this leads to three scenarios for data transmission: master sends data ? slave sends dummy data master sends data ? slave sends data master sends dummy data ? slave sends data figure 17-2: spi master/slave connection serial input buffer (sspbuf) shift register (sspsr) msb lsb sdo sdi processor 1 sck spi master sspm3:sspm0 = 00xxb serial input buffer (sspbuf) shift register (sspsr) lsb msb sdi sdo processor 2 sck spi slave sspm3:sspm0 = 010xb serial clock
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 162 ? 2004 microchip technology inc. 17.3.5 master mode the master can initiate the data transfer at any time because it controls the sck. the master determines when the slave (processor 2, figure 17-2) is to broadcast data by the software protocol. in master mode, the data is transmitted/received as soon as the sspbuf register is written to. if the spi is only going to receive, the sdo output could be dis- abled (programmed as an input). the sspsr register will continue to shift in the signal present on the sdi pin at the programmed clock rate. as each byte is received, it will be loaded into the sspbuf register as if a normal received byte (interrupts and status bits appropriately set). this could be useful in receiver applications as a ?line activity monitor? mode. the clock polarity is selected by appropriately program- ming the ckp bit (sspcon1<4>). this then, would give waveforms for spi communication, as shown in figure 17-3, figure 17-5 and figure 17-6, where the msb is transmitted first. in master mode, the spi clock rate (bit rate) is user-programmable to be one of the following: f osc /4 (or t cy ) f osc /16 (or 4 t cy ) f osc /64 (or 16 t cy ) timer2 output/2 this allows a maximum data rate (at 40 mhz) of 10.00 mbps. figure 17-3 shows the waveforms for master mode. when the cke bit is set, the sdo data is valid before there is a clock edge on sck. the change of the input sample is shown based on the state of the smp bit. the time when the sspbuf is loaded with the received data is shown. figure 17-3: spi mode waveform (master mode) sck (ckp = 0 sck (ckp = 1 sck (ckp = 0 sck (ckp = 1 4 clock modes input sample input sample sdi bit 7 bit 0 sdo bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 bit 7 sdi sspif (smp = 1 ) (smp = 0 ) (smp = 1 ) cke = 1 ) cke = 0 ) cke = 1 ) cke = 0 ) (smp = 0 ) write to sspbuf sspsr to sspbuf sdo bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 (cke = 0 ) (cke = 1 ) next q4 cycle after q2 bit 0
? 2004 microchip technology inc. ds39609b-page 163 pic18f6520/8520/6620/8620/6720/8720 17.3.6 slave mode in slave mode, the data is transmitted and received as the external clock pulses appear on sck. when the last bit is latched, the sspif interrupt flag bit is set. while in slave mode, the external clock is supplied by the external clock source on the sck pin. this external clock must meet the minimum high and low times as specified in the electrical specifications. while in sleep mode, the slave can transmit/receive data. when a byte is received, the device will wake-up from sleep. 17.3.7 slave select synchronization the ss pin allows a synchronous slave mode. the spi must be in slave mode with ss pin control enabled (sspcon1<3:0> = 04h). the pin must not be driven low for the ss pin to function as an input. the data latch must be high. when the ss pin is low, transmis- sion and reception are enabled and the sdo pin is driven. when the ss pin goes high, the sdo pin is no longer driven, even if in the middle of a transmitted byte and becomes a floating output. external pull-up/ pull-down resistors may be desirable, depending on the application. when the spi module resets, the bit counter is forced to ? 0 ?. this can be done by either forcing the ss pin to a high level or clearing the sspen bit. to emulate two-wire communication, the sdo pin can be connected to the sdi pin. when the spi needs to operate as a receiver, the sdo pin can be configured as an input. this disables transmissions from the sdo. the sdi can always be left as an input (sdi function), since it cannot create a bus conflict. figure 17-4: slave synchronization waveform note 1: when the spi is in slave mode with ss pin control enabled (sspcon<3:0> = 0100 ), the spi module will reset if the ss pin is set to v dd . 2: if the spi is used in slave mode with cke set, then the ss pin control must be enabled. sck (ckp = 1 sck (ckp = 0 input sample sdi bit 7 sdo bit 7 bit 6 bit 7 sspif interrupt (smp = 0 ) cke = 0 ) cke = 0 ) (smp = 0 ) write to sspbuf sspsr to sspbuf ss flag bit 0 bit 7 bit 0 next q4 cycle after q2
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 164 ? 2004 microchip technology inc. figure 17-5: spi mode waveform (slave mode with cke = 0 ) figure 17-6: spi mode waveform (slave mode with cke = 1 ) sck (ckp = 1 sck (ckp = 0 input sample sdi bit 7 sdo bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 sspif interrupt (smp = 0 ) cke = 0 ) cke = 0 ) (smp = 0 ) write to sspbuf sspsr to sspbuf ss flag optional next q4 cycle after q2 bit 0 sck (ckp = 1 sck (ckp = 0 input sample sdi bit 7 bit 0 sdo bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 sspif interrupt (smp = 0 ) cke = 1 ) cke = 1 ) (smp = 0 ) write to sspbuf sspsr to sspbuf ss flag not optional next q4 cycle after q2
? 2004 microchip technology inc. ds39609b-page 165 pic18f6520/8520/6620/8620/6720/8720 17.3.8 sleep operation in master mode, all module clocks are halted and the transmission/reception will remain in that state until the device wakes from sleep. after the device returns to normal mode, the module will continue to transmit/ receive data. in slave mode, the spi transmit/receive shift register operates asynchronously to the device. this allows the device to be placed in sleep mode and data to be shifted into the spi transmit/receive shift register. when all 8 bits have been received, the mssp interrupt flag bit will be set and if enabled, will wake the device from sleep. 17.3.9 effects of a reset a reset disables the mssp module and terminates the current transfer. 17.3.10 bus mode compatibility table 17-1 shows the compatibility between the standard spi modes and the states of the ckp and cke control bits. table 17-1: spi bus modes there is also an smp bit, which controls when the data is sampled. table 17-2: registers associated with spi operation standard spi mode terminology control bits state ckp cke 0, 0 0 1 0, 1 0 0 1, 0 1 1 1, 1 1 0 name bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 value on por, bor value on all other resets intcon gie/gieh peie/giel tmr0ie int0ie rbie tmr0if int0if rbif 0000 0000 0000 0000 pir1 pspif adif rcif txif sspif ccp1if tmr2if tmr1if 0000 0000 0000 0000 pie1 pspie adie rcie txie sspie ccp1ie tmr2ie tmr1ie 0000 0000 0000 0000 ipr1 pspip adip rcip txip sspip ccp1ip tmr2ip tmr1ip 0111 1111 0111 1111 trisc portc data direction register 1111 1111 1111 1111 trisf trisf7 trisf6 trisf5 trisf4 trisf3 trisf2 trisf1 trisf0 1111 1111 uuuu uuuu sspbuf synchronous serial port receive buffer/transmit register xxxx xxxx uuuu uuuu sspcon wcol sspov sspen ckp sspm3 sspm2 sspm1 sspm0 0000 0000 0000 0000 sspstat smp cke d/a p s r/w ua bf 0000 0000 0000 0000 legend: x = unknown, u = unchanged, ? = unimplemented, read as ? 0 ?. shaded cells are not used by the mssp in spi mode.
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 166 ? 2004 microchip technology inc. 17.4 i 2 c mode the mssp module in i 2 c mode fully implements all master and slave functions (including general call sup- port) and provides interrupts on start and stop bits in hardware to determine a free bus (multi-master function). the mssp module implements the standard mode specifications, as well as 7-bit and 10-bit addressing. two pins are used for data transfer: serial clock (scl) ? rc3/sck/scl serial data (sda) ? rc4/sdi/sda the user must configure these pins as inputs or outputs through the trisc<4:3> bits. figure 17-7: mssp block diagram (i 2 c mode) 17.4.1 registers the mssp module has six registers for i 2 c operation. these are: mssp control register 1 (sspcon1) mssp control register 2 (sspcon2) mssp status register (sspstat) serial receive/transmit buffer (sspbuf) mssp shift register (sspsr) ? not directly accessible mssp address register (sspadd) sspcon, sspcon2 and sspstat are the control and status registers in i 2 c mode operation. the sspcon and sspcon2 registers are readable and writable. the lower six bits of the sspstat are read-only. the upper two bits of the sspstat are read/write. sspsr is the shift register used for shifting data in or out. sspbuf is the buffer register to which data bytes are written to or read from. sspadd register holds the slave device address when the ssp is configured in i 2 c slave mode. when the ssp is configured in master mode, the lower seven bits of sspadd act as the baud rate generator reload value. in receive operations, sspsr and sspbuf together, create a double-buffered receiver. when sspsr receives a complete byte, it is transferred to sspbuf and the sspif interrupt is set. during transmission, the sspbuf is not double- buffered. a write to sspbuf will write to both sspbuf and sspsr. read write sspsr reg match detect sspadd reg start and stop bit detect sspbuf reg internal data bus addr match set, reset s, p bits (sspstat reg) rc3/sck/scl rc4/ shift clock msb sdi/ lsb sda
? 2004 microchip technology inc. ds39609b-page 167 pic18f6520/8520/6620/8620/6720/8720 register 17-3: sspstat: mssp status register (i 2 c mode) r/w-0 r/w-0 r-0 r-0 r-0 r-0 r-0 r-0 smp cke d/a psr/w ua bf bit 7 bit 0 bit 7 smp: slew rate control bit in master or slave mode: 1 = slew rate control disabled for standard speed mode (100 khz and 1 mhz) 0 = slew rate control enabled for high-speed mode (400 khz) bit 6 cke: smbus select bit in master or slave mode: 1 = enable smbus specific inputs 0 = disable smbus specific inputs bit 5 d/a : data/address bit in master mode: reserved. in slave mode: 1 = indicates that the last byte received or transmitted was data 0 = indicates that the last byte received or transmitted was address bit 4 p: stop bit 1 = indicates that a stop bit has been detected last 0 = stop bit was not detected last note: this bit is cleared on reset and when sspen is cleared. bit 3 s: start bit 1 = indicates that a start bit has been detected last 0 = start bit was not detected last note: this bit is cleared on reset and when sspen is cleared. bit 2 r/w : read/write bit information (i 2 c mode only) in slave mode: 1 = read 0 = write note: this bit holds the r/w bit information following the last address match. this bit is only valid from the address match to the next start bit, stop bit, or not ack bit. in master mode: 1 = transmit is in progress 0 = transmit is not in progress note: oring this bit with sen, rsen, pen, rcen or acken will indicate if the mssp is in active mode. bit 1 ua: update address bit (10-bit slave mode only) 1 = indicates that the user needs to update the address in the sspadd register 0 = address does not need to be updated bit 0 bf: buffer full status bit in transmit mode: 1 = sspbuf is full 0 = sspbuf is empty in receive mode: 1 = sspbuf is full (does not include the ack and stop bits) 0 = sspbuf is empty (does not include the ack and stop bits) legend: r = readable bit w = writable bit u = unimplemented bit, read as ?0? - n = value at por ?1? = bit is set ?0? = bit is cleared x = bit is unknown
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 168 ? 2004 microchip technology inc. register 17-4: sspcon1: mssp control register 1 (i 2 c mode) r/w-0 r/w-0 r/w-0 r/w-0 r/w-0 r/w-0 r/w-0 r/w-0 wcol sspov sspen ckp sspm3 sspm2 sspm1 sspm0 bit 7 bit 0 bit 7 wcol: write collision detect bit in master transmit mode: 1 = a write to the sspbuf register was attempted while the i 2 c conditions were not valid for a transmission to be started (must be cleared in software) 0 = no collision in slave transmit mode: 1 = the sspbuf register is written while it is still transmitting the previous word (must be cleared in software) 0 = no collision in receive mode (master or slave modes) : this is a ?don?t care? bit. bit 6 sspov: receive overflow indicator bit in receive mode: 1 = a byte is received while the sspbuf register is still holding the previous byte (must be cleared in software) 0 = no overflow in transmit mode: this is a ?don?t care? bit in transmit mode. bit 5 sspen: synchronous serial port enable bit 1 = enables the serial port and configures the sda and scl pins as the serial port pins 0 = disables serial port and configures these pins as i/o port pins note: when enabled, the sda and scl pins must be properly configured as input or output. bit 4 ckp: sck release control bit in slave mode: 1 = release clock 0 = holds clock low (clock stretch), used to ensure data setup time in master mode: unused in this mode. bit 3-0 sspm3:sspm0: synchronous serial port mode select bits 1111 = i 2 c slave mode, 10-bit address with start and stop bit interrupts enabled 1110 = i 2 c slave mode, 7-bit address with start and stop bit interrupts enabled 1011 = i 2 c firmware controlled master mode (slave idle) 1000 = i 2 c master mode, clock = f osc /(4 * (sspadd + 1)) 0111 = i 2 c slave mode, 10-bit address 0110 = i 2 c slave mode, 7-bit address note: bit combinations not specifically listed here are either reserved or implemented in spi mode only. legend: r = readable bit w = writable bit u = unimplemented bit, read as ?0? - n = value at por ?1? = bit is set ?0? = bit is cleared x = bit is unknown
? 2004 microchip technology inc. ds39609b-page 169 pic18f6520/8520/6620/8620/6720/8720 register 17-5: sspcon2: mssp control register 2 (i 2 c mode) r/w-0 r/w-0 r/w-0 r/w-0 r/w-0 r/w-0 r/w-0 r/w-0 gcen ackstat ackdt acken rcen pen rsen sen bit 7 bit 0 bit 7 gcen: general call enable bit (slave mode only) 1 = enable interrupt when a general call address (0000h) is received in the sspsr 0 = general call address disabled bit 6 ackstat: acknowledge status bit (master transmit mode only) 1 = acknowledge was not received from slave 0 = acknowledge was received from slave bit 5 ackdt: acknowledge data bit (master receive mode only) 1 = not acknowledge 0 = acknowledge note: value that will be transmitted when the user initiates an acknowledge sequence at the end of a receive. bit 4 acken: acknowledge sequence enable bit (master receive mode only) 1 = initiate acknowledge sequence on sda and scl pins and transmit ackdt data bit. automatically cleared by hardware. 0 = acknowledge sequence idle bit 3 rcen: receive enable bit (master mode only) 1 = enables receive mode for i 2 c 0 = receive idle bit 2 pen: stop condition enable bit (master mode only) 1 = initiate stop condition on sda and scl pins. automatically cleared by hardware. 0 = stop condition idle bit 1 rsen: repeated start condition enabled bit (master mode only) 1 = initiate repeated start condition on sda and scl pins. automatically cleared by hardware. 0 = repeated start condition idle bit 0 sen: start condition enabled/stretch enabled bit in master mode: 1 = initiate start condition on sda and scl pins. automatically cleared by hardware. 0 = start condition idle in slave mode: 1 = clock stretching is enabled for both slave transmit and slave receive (stretch enabled) 0 = clock stretching is disabled note: for bits acken, rcen, pen, rsen, sen: if the i 2 c module is not in the idle mode, this bit may not be set (no spooling) and the sspbuf may not be written (or writes to the sspbuf are disabled). legend: r = readable bit w = writable bit u = unimplemented bit, read as ?0? - n = value at por ?1? = bit is set ?0? = bit is cleared x = bit is unknown
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 170 ? 2004 microchip technology inc. 17.4.2 operation the mssp module functions are enabled by setting mssp enable bit, sspen (sspcon<5>). the sspcon1 register allows control of the i 2 c oper- ation. four mode selection bits (sspcon<3:0>) allow one of the following i 2 c modes to be selected: i 2 c master mode, clock = (f osc /4) x (sspadd + 1) i 2 c slave mode (7-bit address) i 2 c slave mode (10-bit address) i 2 c slave mode (7-bit address), with start and stop bit interrupts enabled i 2 c slave mode (10-bit address), with start and stop bit interrupts enabled i 2 c firmware controlled master mode, slave is idle selection of any i 2 c mode, with the sspen bit set, forces the scl and sda pins to be open-drain, pro- vided these pins are programmed to inputs by setting the appropriate trisc bits. to ensure proper operation of the module, pull-up resistors must be provided externally to the scl and sda pins. 17.4.3 slave mode in slave mode, the scl and sda pins must be config- ured as inputs (trisc<4:3> set). the mssp module will override the input state with the output data when required (slave-transmitter). the i 2 c slave mode hardware will always generate an interrupt on an address match. through the mode select bits, the user can also choose to interrupt on start and stop bits when an address is matched or the data transfer after an address match is received, the hardware automati- cally will generate the acknowledge (ack ) pulse and load the sspbuf register with the received value currently in the sspsr register. any combination of the following conditions will cause the mssp module not to give this ack pulse: the buffer full bit bf (sspstat<0>) was set before the transfer was received. the overflow bit sspov (sspcon<6>) was set before the transfer was received. in this case, the sspsr register value is not loaded into the sspbuf, but bit sspif (pir1<3>) is set. the bf bit is cleared by reading the sspbuf register, while bit sspov is cleared through software. the scl clock input must have a minimum high and low for proper operation. the high and low times of the i 2 c specification, as well as the requirement of the mssp module, are shown in timing parameter #100 and parameter #101. 17.4.3.1 addressing once the mssp module has been enabled, it waits for a start condition to occur. following the start condition, the 8 bits are shifted into the sspsr register. all incom- ing bits are sampled with the rising edge of the clock (scl) line. the value of register sspsr<7:1> is compared to the value of the sspadd register. the address is compared on the falling edge of the eighth clock (scl) pulse. if the addresses match and the bf and sspov bits are clear, the following events occur: 1. the sspsr register value is loaded into the sspbuf register. 2. the buffer full bit bf is set. 3. an ack pulse is generated. 4. mssp interrupt flag bit, sspif (pir1<3>), is set (interrupt is generated, if enabled) on the falling edge of the ninth scl pulse. in 10-bit address mode, two address bytes need to be received by the slave. the five most significant bits (msbs) of the first address byte specify if this is a 10-bit address. bit r/w (sspstat<2>) must specify a write so the slave device will receive the second address byte. for a 10-bit address, the first byte would equal ? 11110 a9 a8 0 ?, where ? a9 ? and ? a8 ? are the two msbs of the address. the sequence of events for 10-bit address is as follows, with steps 7 through 9 for the slave-transmitter: 1. receive first (high) byte of address (bits sspif, bf and bit ua (sspstat<1>) are set). 2. update the sspadd register with second (low) byte of address (clears bit ua and releases the scl line). 3. read the sspbuf register (clears bit bf) and clear flag bit sspif. 4. receive second (low) byte of address (bits sspif, bf and ua are set). 5. update the sspadd register with the first (high) byte of address. if match releases scl line, this will clear bit ua. 6. read the sspbuf register (clears bit bf) and clear flag bit sspif. 7. receive repeated start condition. 8. receive first (high) byte of address (bits sspif and bf are set). 9. read the sspbuf register (clears bit bf) and clear flag bit sspif.
? 2004 microchip technology inc. ds39609b-page 171 pic18f6520/8520/6620/8620/6720/8720 17.4.3.2 reception when the r/w bit of the address byte is clear and an address match occurs, the r/w bit of the sspstat register is cleared. the received address is loaded into the sspbuf register and the sda line is held low (ack ). when the address byte overflow condition exists, then the no acknowledge (ack ) pulse is given. an overflow condition is defined as either bit bf (sspstat<0>) is set, or bit sspov (sspcon1<6>) is set. an mssp interrupt is generated for each data transfer byte. flag bit sspif (pir1<3>) must be cleared in soft- ware. the sspstat register is used to determine the status of the byte. if sen is enabled (sspcon1<0> = 1 ), rc3/sck/scl will be held low (clock stretch) following each data transfer. the clock must be released by setting bit ckp (sspcon<4>). see section 17.4.4 ?clock stretching? for more detail. 17.4.3.3 transmission when the r/w bit of the incoming address byte is set and an address match occurs, the r/w bit of the sspstat register is set. the received address is loaded into the sspbuf register. the ack pulse will be sent on the ninth bit and pin rc3/sck/scl is held low, regardless of sen (see section 17.4.4 ?clock stretching? , for more detail). by stretching the clock, the master will be unable to assert another clock pulse until the slave is done preparing the transmit data. the transmit data must be loaded into the sspbuf register, which also loads the sspsr register. then pin rc3/ sck/scl should be enabled by setting bit ckp (sspcon1<4>). the eight data bits are shifted out on the falling edge of the scl input. this ensures that the sda signal is valid during the scl high time (figure 17-9). the ack pulse from the master-receiver is latched on the rising edge of the ninth scl input pulse. if the sda line is high (not ack ), then the data transfer is complete. in this case, when the ack is latched by the slave, the slave logic is reset (resets sspstat regis- ter) and the slave monitors for another occurrence of the start bit. if the sda line was low (ack ), the next transmit data must be loaded into the sspbuf register. again, pin rc3/sck/scl must be enabled by setting bit ckp. an mssp interrupt is generated for each data transfer byte. the sspif bit must be cleared in software and the sspstat register is used to determine the status of the byte. the sspif bit is set on the falling edge of the ninth clock pulse.
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 172 ? 2004 microchip technology inc. figure 17-8: i 2 c slave mode timing with sen = 0 (reception, 7-bit address) sda scl sspif bf (sspstat<0>) sspov (sspcon<6>) s 1 2 34 56 7 8 91 234 5 67 89 1 23 45 7 89 p a7 a6 a5 a4 a3 a2 a1 d7 d6 d5 d4 d3 d2 d1 d0 d7 d6 d5 d4 d3 d1 d0 ack receiving data ack receiving data r/w = 0 ack receiving address cleared in software sspbuf is read bus master terminates transfer sspov is set because sspbuf is still full. ack is not sent. d2 6 (pir1<3>) ckp (ckp does not reset to ? 0 ? when sen = 0 )
? 2004 microchip technology inc. ds39609b-page 173 pic18f6520/8520/6620/8620/6720/8720 figure 17-9: i 2 c slave mode timing (transmission, 7-bit address) sda scl sspif (pir1<3>) bf (sspstat<0>) a6 a5 a4 a3 a2 a1 d6 d5 d4 d3 d2 d1 d0 1 2 3 4 5 6 7 8 2 3 4 5 6 7 8 9 sspbuf is written in software cleared in software scl held low while cpu responds to sspif from sspif isr data in sampled s ack transmitting data r/w = 1 ack receiving address a7 d7 9 1 d6 d5 d4 d3 d2 d1 d0 2 3 4 5 6 7 8 9 sspbuf is written in software cleared in software from sspif isr transmitting data d7 1 ckp p ack ckp is set in software ckp is set in software
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 174 ? 2004 microchip technology inc. figure 17-10: i 2 c slave mode timing with sen = 0 (reception, 10-bit address) sda scl sspif bf (sspstat<0>) s 123456789 123456789 12345 789 p 1 1 1 1 0 a9a8 a7 a6a5a4a3a2a1 a0 d7 d6d5d4d3 d1d0 receive data byte ack r/w = 0 ack receive first byte of address cleared in software d2 6 (pir1<3>) cleared in software receive second byte of address cleared by hardware when sspadd is updated with low byte of address ua (sspstat<1>) clock is held low until update of sspadd has taken place ua is set indicating that the sspadd needs to be updated ua is set indicating that sspadd needs to be updated cleared by hardware when sspadd is updated with high byte of address sspbuf is written with contents of sspsr dummy read of sspbuf to clear bf flag ack ckp 12345 789 d7 d6 d5 d4 d3 d1 d0 receive data byte bus master terminates transfer d2 6 ack cleared in software cleared in software sspov (sspcon<6>) sspov is set because sspbuf is still full. ack is not sent. (ckp does not reset to ? 0 ? when sen = 0 ) clock is held low until update of sspadd has taken place
? 2004 microchip technology inc. ds39609b-page 175 pic18f6520/8520/6620/8620/6720/8720 figure 17-11: i 2 c slave mode timing (transmission, 10-bit address) sda scl sspif bf (sspstat<0>) s 1234 5 6789 1 2345 678 9 12 345 78 9 p 1 1 1 1 0 a9a8 a7 a6a5a4a3a2a1 a0 1 1 1 1 0 a8 r/w = 1 ack ack r/w = 0 ack receive first byte of address cleared in software bus master terminates transfer a9 6 (pir1<3>) receive second byte of address cleared by hardware when sspadd is updated with low byte of address ua (sspstat<1>) clock is held low until update of sspadd has taken place ua is set indicating that the sspadd needs to be updated ua is set indicating that sspadd needs to be updated cleared by hardware when sspadd is updated with high byte of address sspbuf is written with contents of sspsr dummy read of sspbuf to clear bf flag receive first byte of address 12345 789 d7 d6 d5 d4 d3 d1 ack d2 6 transmitting data byte d0 dummy read of sspbuf to clear bf flag sr cleared in software write of sspbuf initiates transmit cleared in software completion of clears bf flag ckp (sspcon<4>) ckp is set in software ckp is automatically cleared in hardware, holding scl low clock is held low until update of sspadd has taken place data transmission clock is held low until ckp is set to ? 1 ? bf flag is clear third address sequence at the end of the
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 176 ? 2004 microchip technology inc. 17.4.4 clock stretching both 7- and 10-bit slave modes implement automatic clock stretching during a transmit sequence. the sen bit (sspcon2<0>) allows clock stretching to be enabled during receives. setting sen will cause the scl pin to be held low at the end of each data receive sequence. 17.4.4.1 clock stretching for 7-bit slave receive mode (sen = 1 ) in 7-bit slave receive mode, on the falling edge of the ninth clock at the end of the ack sequence, if the bf bit is set, the ckp bit in the sspcon1 register is automatically cleared, forcing the scl output to be held low. the ckp being cleared to ? 0 ? will assert the scl line low. the ckp bit must be set in the user?s isr before reception is allowed to continue. by holding the scl line low, the user has time to service the isr and read the contents of the sspbuf before the master device can initiate another receive sequence. this will prevent buffer overruns from occurring (see figure 17-13). 17.4.4.2 clock stretching for 10-bit slave receive mode (sen = 1 ) in 10-bit slave receive mode, during the address sequence, clock stretching automatically takes place but ckp is not cleared. during this time, if the ua bit is set after the ninth clock, clock stretching is initiated. the ua bit is set after receiving the upper byte of the 10-bit address and following the receive of the second byte of the 10-bit address with the r/w bit cleared to ? 0 ?. the release of the clock line occurs upon updating sspadd. clock stretching will occur on each data receive sequence, as described in 7-bit mode. 17.4.4.3 clock stretching for 7-bit slave transmit mode 7-bit slave transmit mode implements clock stretching by clearing the ckp bit after the falling edge of the ninth clock, if the bf bit is clear. this occurs, regardless of the state of the sen bit. the user?s isr must set the ckp bit before transmis- sion is allowed to continue. by holding the scl line low, the user has time to service the isr and load the contents of the sspbuf before the master device can initiate another transmit sequence (see figure 17-9). 17.4.4.4 clock stretching for 10-bit slave transmit mode in 10-bit slave transmit mode, clock stretching is con- trolled during the first two address sequences by the state of the ua bit, just as it is in 10-bit slave receive mode. the first two addresses are followed by a third address sequence, which contains the high-order bits of the 10-bit address and the r/w bit set to ? 1 ?. after the third address sequence is performed, the ua bit is not set, the module is now configured in transmit mode and clock stretching is controlled as in 7-bit slave transmit mode (see figure 17-11). note 1: if the user reads the contents of the sspbuf before the falling edge of the ninth clock, thus clearing the bf bit, the ckp bit will not be cleared and clock stretching will not occur. 2: the ckp bit can be set in software, regardless of the state of the bf bit. the user should be careful to clear the bf bit in the isr before the next receive sequence, in order to prevent an overflow condition. note: if the user polls the ua bit and clears it by updating the sspadd register before the falling edge of the ninth clock occurs and if the user hasn?t cleared the bf bit by read- ing the sspbuf register before that time, then the ckp bit will still not be asserted low. clock stretching on the basis of the state of the bf bit only occurs during a data sequence, not an address sequence. note 1: if the user loads the contents of sspbuf, setting the bf bit before the falling edge of the ninth clock, the ckp bit will not be cleared and clock stretching will not occur. 2: the ckp bit can be set in software, regardless of the state of the bf bit.
? 2004 microchip technology inc. ds39609b-page 177 pic18f6520/8520/6620/8620/6720/8720 17.4.4.5 clock synchronization and the ckp bit when the ckp bit is cleared, the scl output is forced to ? 0 ?. however, clearing the ckp bit will not assert the scl output low until the scl output is already sam- pled low. therefore, the ckp bit will not assert the scl line until an external i 2 c master device has already asserted the scl line. the scl output will remain low until the ckp bit is set and all other devices on the i 2 c bus have deasserted scl. this ensures that a write to the ckp bit will not violate the minimum high time requirement for scl (see figure 17-12). figure 17-12: clock synchronization timing sda scl dx-1 dx wr q1 q2 q3 q4 q1 q2 q3 q4 q1 q2 q3 q4 q1 q2 q3 q4 q1 q2 q3 q4 q1 q2 q3 q4 q1 q2 q3 q4 sspcon ckp master device deasserts clock master device asserts clock
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 178 ? 2004 microchip technology inc. figure 17-13: i 2 c slave mode timing with sen = 1 (reception, 7-bit address) sda scl sspif bf (sspstat<0>) sspov (sspcon<6>) s 1 2345 67 89 1 2345 67 89 1 23 45 7 89 p a7 a6 a5 a4 a3 a2 a1 d7 d6 d5 d4 d3 d2 d1 d0 d7 d6 d5 d4 d3 d1 d0 ack receiving data ack receiving data r/w = 0 ack receiving address cleared in software sspbuf is read bus master terminates transfer sspov is set because sspbuf is still full. ack is not sent. d2 6 (pir1<3>) ckp ckp written to ? 1 ? in if bf is cleared prior to the falling edge of the 9th clock, ckp will not be reset to ? 0 ? and no clock stretching will occur software clock is held low until ckp is set to ? 1 ? clock is not held low because buffer full bit is clear prior to falling edge of 9th clock clock is not held low because ack = 1 bf is set after falling edge of the 9th clock, ckp is reset to ? 0 ? and clock stretching occurs
? 2004 microchip technology inc. ds39609b-page 179 pic18f6520/8520/6620/8620/6720/8720 figure 17-14: i 2 c slave mode timing sen = 1 (reception, 10-bit address) sda scl sspif bf (sspstat<0>) s 123456789 123456789 12345 789 p 1 1 1 1 0 a9a8 a7 a6 a5a4a3a2a1 a0 d7d6d5d4d3 d1 d0 receive data byte ack r/w = 0 ack receive first byte of address cleared in software d2 6 (pir1<3>) cleared in software receive second byte of address cleared by hardware when sspadd is updated with low byte of address after falling edge ua (sspstat<1>) clock is held low until update of sspadd has taken place ua is set indicating that the sspadd needs to be updated ua is set indicating that sspadd needs to be updated cleared by hardware when sspadd is updated with high byte of address after falling edge sspbuf is written with contents of sspsr dummy read of sspbuf to clear bf flag ack ckp 12345 789 d7 d6 d5 d4 d3 d1 d0 receive data byte bus master terminates transfer d2 6 ack cleared in software cleared in software sspov (sspcon<6>) ckp written to ? 1 ? note: an update of the sspadd register before the falling edge of the ninth clock will have no effect on ua and ua will remain set note: an update of the sspadd register before the falling edge of the ninth clock will have no effect on ua and ua will remain set in software clock is held low until update of sspadd has taken place of ninth clock of ninth clock sspov is set because sspbuf is still full. ack is not sent. dummy read of sspbuf to clear bf flag clock is held low until ckp is set to ? 1 ? clock is not held low because ack = 1
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 180 ? 2004 microchip technology inc. 17.4.5 general call address support the addressing procedure for the i 2 c bus is such that the first byte after the start condition usually deter- mines which device will be the slave addressed by the master. the exception is the general call address, which can address all devices. when this address is used, all devices should, in theory, respond with an acknowledge. the general call address is one of eight addresses reserved for specific purposes by the i 2 c protocol. it consists of all ? 0 ?s with r/w = 0 . the general call address is recognized when the gen- eral call enable bit (gcen) is enabled (sspcon2<7> set). following a start bit detect, 8 bits are shifted into the sspsr and the address is compared against the sspadd. it is also compared to the general call address and fixed in hardware. if the general call address matches, the sspsr is transferred to the sspbuf, the bf flag bit is set (eighth bit) and on the falling edge of the ninth bit (ack bit), the sspif interrupt flag bit is set. when the interrupt is serviced, the source for the inter- rupt can be checked by reading the contents of the sspbuf. the value can be used to determine if the address was device specific or a general call address. in 10-bit mode, the sspadd is required to be updated for the second half of the address to match and the ua bit is set (sspstat<1>). if the general call address is sampled when the gcen bit is set, while the slave is configured in 10-bit address mode, then the second half of the address is not necessary, the ua bit will not be set and the slave will begin receiving data after the acknowledge (figure 17-15). figure 17-15: slave mode general call address sequence (7 or 10-bit address mode) sda scl s sspif bf (sspstat<0>) sspov (sspcon1<6>) cleared in software sspbuf is read r/w = 0 ack general call address address is compared to general call address gcen (sspcon2<7>) receiving data ack 123456789123456789 d7 d6 d5 d4 d3 d2 d1 d0 after ack , set interrupt ? 0 ? ? 1 ?
? 2004 microchip technology inc. ds39609b-page 181 pic18f6520/8520/6620/8620/6720/8720 17.4.6 master mode master mode is enabled by setting and clearing the appropriate sspm bits in sspcon1 and by setting the sspen bit. in master mode, the scl and sda lines are manipulated by the mssp hardware. master mode of operation is supported by interrupt generation on the detection of the start and stop conditions. the stop (p) and start (s) bits are cleared from a reset, or when the mssp module is disabled. control of the i 2 c bus may be taken when the p bit is set or the bus is idle, with both the s and p bits clear. in firmware controlled master mode, user code conducts all i 2 c bus operations based on start and stop bit conditions. once master mode is enabled, the user has six options. 1. assert a start condition on sda and scl. 2. assert a repeated start condition on sda and scl. 3. write to the sspbuf register initiating transmission of data/address. 4. configure the i 2 c port to receive data. 5. generate an acknowledge condition at the end of a received byte of data. 6. generate a stop condition on sda and scl. the following events will cause ssp interrupt flag bit, sspif, to be set (ssp interrupt if enabled): start condition stop condition data transfer byte transmitted/received acknowledge transmit repeated start figure 17-16: mssp block diagram (i 2 c master mode) note: the mssp module, when configured in i 2 c master mode, does not allow queueing of events. for instance, the user is not allowed to initiate a start condition and immediately write the sspbuf register to initiate transmission before the start condi- tion is complete. in this case, the sspbuf will not be written to and the wcol bit will be set, indicating that a write to the sspbuf did not occur. read write sspsr start bit, stop bit, start bit detect sspbuf internal data bus set/reset, s, p, wcol (sspstat) shift clock msb lsb sda acknowledge generate stop bit detect write collision detect clock arbitration state counter for end of xmit/rcv scl scl in bus collision sda in receive enable clock cntl clock arbitrate/wcol detect (hold off clock source) sspadd<6:0> baud set sspif, bclif reset ackstat, pen (sspcon2) rate generator sspm3:sspm0
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 182 ? 2004 microchip technology inc. 17.4.6.1 i 2 c master mode operation the master device generates all of the serial clock pulses and the start and stop conditions. a transfer is ended with a stop condition or with a repeated start condition. since the repeated start condition is also the beginning of the next serial transfer, the i 2 c bus will not be released. in master transmitter mode, serial data is output through sda, while scl outputs the serial clock. the first byte transmitted contains the slave address of the receiving device (7 bits) and the read/write (r/w ) bit. in this case, the r/w bit will be logic ? 0 ?. serial data is transmitted 8 bits at a time. after each byte is transmit- ted, an acknowledge bit is received. start and stop conditions are output to indicate the beginning and the end of a serial transfer. in master receive mode, the first byte transmitted con- tains the slave address of the transmitting device (7 bits) and the r/w bit. in this case, the r/w bit will be logic ? 1 ?. thus, the first byte transmitted is a 7-bit slave address followed by a ? 1 ? to indicate receive bit. serial data is received via sda, while scl outputs the serial clock. serial data is received 8 bits at a time. after each byte is received, an acknowledge bit is transmitted. start and stop conditions indicate the beginning and end of transmission. the baud rate generator used for the spi mode operation is used to set the scl clock frequency for either 100 khz, 400 khz or 1 mhz i 2 c operation. see section 17.4.7 ?baud rate generator? , for more information. a typical transmit sequence would go as follows: 1. the user generates a start condition by setting the start enable bit, sen (sspcon2<0>). 2. sspif is set. the mssp module will wait the required start time before any other operation takes place. 3. the user loads the sspbuf with the slave address to transmit. 4. address is shifted out the sda pin until all 8 bits are transmitted. 5. the mssp module shifts in the ack bit from the slave device and writes its value into the sspcon2 register (sspcon2<6>). 6. the mssp module generates an interrupt at the end of the ninth clock cycle by setting the sspif bit. 7. the user loads the sspbuf with eight bits of data. 8. data is shifted out the sda pin until all 8 bits are transmitted. 9. the mssp module shifts in the ack bit from the slave device and writes its value into the sspcon2 register (sspcon2<6>). 10. the mssp module generates an interrupt at the end of the ninth clock cycle by setting the sspif bit. 11. the user generates a stop condition by setting the stop enable bit pen (sspcon2<2>). 12. interrupt is generated once the stop condition is complete.
? 2004 microchip technology inc. ds39609b-page 183 pic18f6520/8520/6620/8620/6720/8720 17.4.7 baud rate generator in i 2 c master mode, the baud rate generator (brg) reload value is placed in the lower 7 bits of the sspadd register (figure 17-17). when a write occurs to sspbuf, the baud rate generator will automatically begin counting. the brg counts down to ? 0 ? and stops until another reload has taken place. the brg count is decremented twice per instruction cycle (t cy ) on the q2 and q4 clocks. in i 2 c master mode, the brg is reloaded automatically. once the given operation is complete (i.e., transmis- sion of the last data bit is followed by ack ), the internal clock will automatically stop counting and the scl pin will remain in its last state. table 15-3 demonstrates clock rates based on instruction cycles and the brg value loaded into sspadd. figure 17-17: baud rate generator block diagram table 17-3: i 2 c clock rate w/brg sspm3:sspm0 brg down counter clko f osc /4 sspadd<6:0> sspm3:sspm0 scl reload control reload f cy f cy *2 brg value f scl (2 rollovers of brg) 10 mhz 20 mhz 19h 400 khz (1) 10 mhz 20 mhz 20h 312.5 khz 10 mhz 20 mhz 3fh 100 khz 4 mhz 8 mhz 0ah 400 khz (1) 4 mhz 8 mhz 0dh 308 khz 4 mhz 8 mhz 28h 100 khz 1 mhz 2 mhz 03h 333 khz (1) 1 mhz 2 mhz 0ah 100 khz 1 mhz 2 mhz 00h 1 mhz (1) note 1: the i 2 c interface does not conform to the 400 khz i 2 c specification (which applies to rates greater than 100 khz) in all details, but may be used with care where higher rates are required by the application.
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 184 ? 2004 microchip technology inc. 17.4.7.1 clock arbitration clock arbitration occurs when the master, during any receive, transmit or repeated start/stop condition, deasserts the scl pin (scl allowed to float high). when the scl pin is allowed to float high, the baud rate generator (brg) is suspended from counting until the scl pin is actually sampled high. when the scl pin is sampled high, the baud rate generator is reloaded with the contents of sspadd<6:0> and begins counting. this ensures that the scl high time will always be at least one brg rollover count, in the event that the clock is held low by an external device (figure 15-18). figure 17-18: baud rate generator timing with clock arbitration sda scl scl deasserted but slave holds dx-1 dx brg scl is sampled high, reload takes place and brg starts its count 03h 02h 01h 00h (hold off) 03h 02h reload brg value scl low (clock arbitration) scl allowed to transition high brg decrements on q2 and q4 cycles
? 2004 microchip technology inc. ds39609b-page 185 pic18f6520/8520/6620/8620/6720/8720 17.4.8 i 2 c master mode start condition timing to initiate a start condition, the user sets the start con- dition enable bit, sen (sspcon2<0>). if the sda and scl pins are sampled high, the baud rate generator is reloaded with the contents of sspadd<6:0> and starts its count. if scl and sda are both sampled high when the baud rate generator times out (t brg ), the sda pin is driven low. the action of the sda being driven low, while scl is high, is the start condition and causes the s bit (sspstat<3>) to be set. following this, the baud rate generator is reloaded with the con- tents of sspadd<6:0> and resumes its count. when the baud rate generator times out (t brg ), the sen bit (sspcon2<0>) will be automatically cleared by hardware, the baud rate generator is suspended, leaving the sda line held low and the start condition is complete. 17.4.8.1 wcol status flag if the user writes the sspbuf when a start sequence is in progress, the wcol is set and the contents of the buffer are unchanged (the write doesn?t occur). figure 17-19: first start bit timing note: if at the beginning of the start condition, the sda and scl pins are already sam- pled low, or if during the start condition the scl line is sampled low before the sda line is driven low, a bus collision occurs, the bus collision interrupt flag, bclif, is set, the start condition is aborted and the i 2 c module is reset into its idle state. note: because queueing of events is not allowed, writing to the lower 5 bits of sspcon2 is disabled until the start condition is complete. sda scl s t brg 1st bit 2nd bit t brg sda = 1 , at completion of start bit, scl = 1 write to sspbuf occurs here t brg hardware clears sen bit t brg write to sen bit occurs here set s bit (sspstat<3>) and sets sspif bit
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 186 ? 2004 microchip technology inc. 17.4.9 i 2 c master mode repeated start condition timing a repeated start condition occurs when the rsen bit (sspcon2<1>) is programmed high and the i 2 c logic module is in the idle state. when the rsen bit is set, the scl pin is asserted low. when the scl pin is sam- pled low, the baud rate generator is loaded with the contents of sspadd<5:0> and begins counting. the sda pin is released (brought high) for one baud rate generator count (t brg ). when the baud rate genera- tor times out, if sda is sampled high, the scl pin will be deasserted (brought high). when scl is sampled high, the baud rate generator is reloaded with the contents of sspadd<6:0> and begins counting. sda and scl must be sampled high for one t brg . this action is then followed by assertion of the sda pin (sda = 0 ) for one t brg , while scl is high. following this, the rsen bit (sspcon2<1>) will be automatically cleared and the baud rate generator will not be reloaded, leaving the sda pin held low. as soon as a start condition is detected on the sda and scl pins, the s bit (sspstat<3>) will be set. the sspif bit will not be set until the baud rate generator has timed out. immediately following the setting of the sspif bit, the user may write the sspbuf with the 7-bit address in 7-bit mode, or the default first address in 10-bit mode. after the first eight bits are transmitted and an ack is received, the user may then transmit an additional eight bits of address (10-bit mode) or eight bits of data (7-bit mode). 17.4.9.1 wcol status flag if the user writes the sspbuf when a repeated start sequence is in progress, the wcol is set and the contents of the buffer are unchanged (the write does not occur). figure 17-20: repeat start condition waveform note 1: if rsen is programmed while any other event is in progress, it will not take effect. 2: a bus collision during the repeated start condition occurs if: sda is sampled low when scl goes from low-to-high. scl goes low before sda is asserted low. this may indicate that another master is attempting to transmit a data ? 1 ?. note: because queueing of events is not allowed, writing of the lower 5 bits of sspcon2 is disabled until the repeated start condition is complete. sda scl sr = repeated start write to sspcon2 write to sspbuf occurs here falling edge of ninth clock end of xmit at completion of start bit, hardware clears rsen bit 1st bit s bit set by hardware (sspstat<3>) t brg t brg sda = 1 , sda = 1 , scl (no change). scl = 1 occurs here. t brg t brg t brg and sets sspif rsen bit set
? 2004 microchip technology inc. ds39609b-page 187 pic18f6520/8520/6620/8620/6720/8720 17.4.10 i 2 c master mode transmission transmission of a data byte, a 7-bit address, or the other half of a 10-bit address is accomplished by simply writing a value to the sspbuf register. this action will set the buffer full flag bit, bf and allow the baud rate generator to begin counting and start the next trans- mission. each bit of address/data will be shifted out onto the sda pin after the falling edge of scl is asserted (see data hold time specification parameter #106). scl is held low for one baud rate generator rollover count (t brg ). data should be valid before scl is released high (see data setup time specification parameter #107). when the scl pin is released high, it is held that way for t brg . the data on the sda pin must remain stable for that duration and some hold time, after the next falling edge of scl. after the eighth bit is shifted out (the falling edge of the eighth clock), the bf flag is cleared and the master releases sda. this allows the slave device being addressed to respond with an ack bit during the ninth bit time if an address match occurred, or if data was received prop- erly. the status of ack is written into the ackdt bit on the falling edge of the ninth clock. if the master receives an acknowledge, the acknowledge status bit, ackstat, is cleared. if not, the bit is set. after the ninth clock, the sspif bit is set and the master clock (baud rate generator) is suspended until the next data byte is loaded into the sspbuf, leaving scl low and sda unchanged (figure 17-21). after the write to the sspbuf, each address bit will be shifted out on the falling edge of scl, until all seven address bits and the r/w bit are completed. on the fall- ing edge of the eighth clock, the master will deassert the sda pin, allowing the slave to respond with an acknowledge. on the falling edge of the ninth clock, the master will sample the sda pin to see if the address was recognized by a slave. the status of the ack bit is loaded into the ackstat status bit (sspcon2<6>). following the falling edge of the ninth clock transmis- sion of the address, the sspif is set, the bf flag is cleared and the baud rate generator is turned off until another write to the sspbuf takes place, holding scl low and allowing sda to float. 17.4.10.1 bf status flag in transmit mode, the bf bit (sspstat<0>) is set when the cpu writes to sspbuf and is cleared when all 8 bits are shifted out. 17.4.10.2 wcol status flag if the user writes the sspbuf when a transmit is already in progress (i.e., sspsr is still shifting out a data byte), the wcol is set and the contents of the buffer are unchanged (the write doesn?t occur). wcol must be cleared in software. 17.4.10.3 ackstat status flag in transmit mode, the ackstat bit (sspcon2<6>) is cleared when the slave has sent an acknowledge (ack = 0 ) and is set when the slave does not acknowl- edge (ack = 1 ). a slave sends an acknowledge when it has recognized its address (including a general call), or when the slave has properly received its data. 17.4.11 i 2 c master mode reception master mode reception is enabled by programming the receive enable bit, rcen (sspcon2<3>). the baud rate generator begins counting and on each rollover, the state of the scl pin changes (high-to-low/ low-to-high) and data is shifted into the sspsr. after the falling edge of the eighth clock, the receive enable flag is automatically cleared, the contents of the sspsr are loaded into the sspbuf, the bf flag bit is set, the sspif flag bit is set and the baud rate gener- ator is suspended from counting, holding scl low. the mssp is now in idle state, awaiting the next command. when the buffer is read by the cpu, the bf flag bit is automatically cleared. the user can then send an acknowledge bit at the end of reception by setting the acknowledge sequence enable bit, acken (sspcon2<4>). 17.4.11.1 bf status flag in receive operation, the bf bit is set when an address or data byte is loaded into sspbuf from sspsr. it is cleared when the sspbuf register is read. 17.4.11.2 sspov status flag in receive operation, the sspov bit is set when 8 bits are received into the sspsr and the bf flag bit is already set from a previous reception. 17.4.11.3 wcol status flag if the user writes the sspbuf when a receive is already in progress (i.e., sspsr is still shifting in a data byte), the wcol bit is set and the contents of the buffer are unchanged (the write doesn?t occur). note: the mssp module must be in an idle state before the rcen bit is set, or the rcen bit will be disregarded.
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 188 ? 2004 microchip technology inc. figure 17-21: i 2 c master mode waveform (transmission, 7 or 10-bit address) sda scl sspif bf (sspstat<0>) sen a7 a6 a5 a4 a3 a2 a1 ack = 0 d7 d6 d5 d4 d3 d2 d1 d0 ack transmitting data or second half r/w = 0 transmit address to slave 123456789 123456789 p cleared in software service routine sspbuf is written in software from ssp interrupt after start condition, sen cleared by hardware s sspbuf written with 7-bit address and r/w , start transmit scl held low while cpu responds to sspif sen = 0 of 10-bit address write sspcon2<0> sen = 1 , start condition begins from slave, clear ackstat bit sspcon2<6> ackstat in sspcon2 = 1 cleared in software sspbuf written pen cleared in software r/w
? 2004 microchip technology inc. ds39609b-page 189 pic18f6520/8520/6620/8620/6720/8720 figure 17-22: i 2 c master mode waveform (reception, 7-bit address) p 9 8 7 6 5 d0 d1 d2 d3 d4 d5 d6 d7 s a7 a6 a5 a4 a3 a2 a1 sda scl 12 3 4 5 6 7 8 9 12 3 4 5 678 9 1234 bus master terminates transfer ack receiving data from slave receiving data from slave d0 d1 d2 d3 d4 d5 d6 d7 ack r/w = 1 transmit address to slave sspif bf ack is not sent write to sspcon2<0> (sen = 1 ), write to sspbuf occurs here ack from slave master configured as a receiver by programming sspcon2<3> (rcen = 1 ) pen bit = 1 written here data shifted in on falling edge of clk cleared in software start xmit sen = 0 sspov sda = 0 , scl = 1 while cpu (sspstat<0>) ack last bit is shifted into sspsr and contents are unloaded into sspbuf cleared in software cleared in software set sspif interrupt at end of receive set p bit (sspstat<4>) and sspif cleared in software ack from master set sspif at end set sspif interrupt at end of acknowledge sequence set sspif interrupt at end of acknow- ledge sequence of receive set acken, start acknowledge sequence sspov is set because sspbuf is still full sda = ackdt = 1 rcen cleared automatically rcen = 1 start next receive write to sspcon2<4> to start acknowledge sequence sda = ackdt (sspcon2<5>) = 0 rcen cleared automatically responds to sspif acken begin start condition cleared in software sda = ackdt = 0
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 190 ? 2004 microchip technology inc. 17.4.12 acknowledge sequence timing an acknowledge sequence is enabled by setting the acknowledge sequence enable bit, acken (sspcon2<4>). when this bit is set, the scl pin is pulled low and the contents of the acknowledge data bit are presented on the sda pin. if the user wishes to gen- erate an acknowledge, then the ackdt bit should be cleared. if not, the user should set the ackdt bit before starting an acknowledge sequence. the baud rate generator then counts for one rollover period (t brg ) and the scl pin is deasserted (pulled high). when the scl pin is sampled high (clock arbitration), the baud rate generator counts for t brg . the scl pin is then pulled low. following this, the acken bit is automatically cleared, the baud rate generator is turned off and the mssp module then goes into idle mode (figure 17-23). 17.4.12.1 wcol status flag if the user writes the sspbuf when an acknowledge sequence is in progress, then wcol is set and the contents of the buffer are unchanged (the write doesn?t occur). 17.4.13 stop condition timing a stop bit is asserted on the sda pin at the end of a receive/transmit by setting the stop sequence enable bit, pen (sspcon2<2>). at the end of a receive/ transmit, the scl line is held low after the falling edge of the ninth clock. when the pen bit is set, the master will assert the sda line low. when the sda line is sam- pled low, the baud rate generator is reloaded and counts down to ? 0 ?. when the baud rate generator times out, the scl pin will be brought high and one t brg (baud rate generator rollover count) later, the sda pin will be deasserted. when the sda pin is sam- pled high while scl is high, the p bit (sspstat<4>) is set. a t brg later, the pen bit is cleared and the sspif bit is set (figure 17-24). 17.4.13.1 wcol status flag if the user writes the sspbuf when a stop sequence is in progress, then the wcol bit is set and the contents of the buffer are unchanged (the write doesn?t occur). figure 17-23: acknowledge sequence waveform figure 17-24: stop cond ition receive or transmit mode sda scl sspif set at the end acknowledge sequence starts here, write to sspcon2 acken automatically cleared cleared in t brg t brg of receive 8 acken = 1 , ackdt = 0 d0 9 sspif software sspif set at the end of acknowledge sequence cleared in software note: t brg = one baud rate generator period. ack scl sda sda asserted low before rising edge of clock write to sspcon2 set pen falling edge of scl = 1 for t brg , followed by sda = 1 for t brg 9th clock scl brought high after t brg note: t brg = one baud rate generator period. t brg t brg after sda sampled high. p bit (sspstat<4>) is set. t brg to setup stop condition ack p t brg pen bit (sspcon2<2>) is cleared by hardware and the sspif bit is set
? 2004 microchip technology inc. ds39609b-page 191 pic18f6520/8520/6620/8620/6720/8720 17.4.14 sleep operation while in sleep mode, the i 2 c module can receive addresses or data and when an address match or complete byte transfer occurs, wake the processor from sleep (if the mssp interrupt is enabled). 17.4.15 effect of a reset a reset disables the mssp module and terminates the current transfer. 17.4.16 multi-master mode in multi-master mode, the interrupt generation on the detection of the start and stop conditions allows the determination of when the bus is free. the stop (p) and start (s) bits are cleared from a reset or when the mssp module is disabled. control of the i 2 c bus may be taken when the p bit (sspstat<4>) is set, or the bus is idle with both the s and p bits clear. when the bus is busy, enabling the ssp interrupt will generate the interrupt when the stop condition occurs. in multi-master operation, the sda line must be moni- tored for arbitration, to see if the signal level is the expected output level. this check is performed in hardware, with the result placed in the bclif bit. the states where arbitration can be lost are: address transfer data transfer a start condition a repeated start condition an acknowledge condition 17.4.17 multi -master communication, bus collision and bus arbitration multi-master mode support is achieved by bus arbitra- tion. when the master outputs address/data bits onto the sda pin, arbitration takes place when the master outputs a ? 1 ? on sda, by letting sda float high and another master asserts a ? 0 ?. when the scl pin floats high, data should be stable. if the expected data on sda is a ? 1 ? and the data sampled on the sda pin = 0 , then a bus collision has taken place. the master will set the bus collision interrupt flag, bclif and reset the i 2 c port to its idle state (figure 17-25). if a transmit was in progress when the bus collision occurred, the transmission is halted, the bf flag is cleared, the sda and scl lines are deasserted and the sspbuf can be written to. when the user services the bus collision interrupt service routine and if the i 2 c bus is free, the user can resume communication by asserting a start condition. if a start, repeated start, stop, or acknowledge condi- tion was in progress when the bus collision occurred, the condition is aborted, the sda and scl lines are deasserted and the respective control bits in the sspcon2 register are cleared. when the user ser- vices the bus collision interrupt service routine and if the i 2 c bus is free, the user can resume communication by asserting a start condition. the master will continue to monitor the sda and scl pins. if a stop condition occurs, the sspif bit will be set. a write to the sspbuf will start the transmission of data at the first data bit, regardless of where the transmitter left off when the bus collision occurred. in multi-master mode, the interrupt generation on the detection of start and stop conditions allows the determi- nation of when the bus is free. control of the i 2 c bus can be taken when the p bit is set in the sspstat register, or the bus is idle and the s and p bits are cleared. figure 17-25: bus collision timing for transmit and acknowledge sda scl bclif sda released sda line pulled low by another source sample sda. while scl is high, data doesn?t match what is driven bus collision has occurred. set bus collision interrupt (bclif) by the master. by master data changes while scl = 0
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 192 ? 2004 microchip technology inc. 17.4.17.1 bus collision during a start condition during a start condition, a bus collision occurs if: a) sda or scl are sampled low at the beginning of the start condition (figure 17-26). b) scl is sampled low before sda is asserted low (figure 17-27). during a start condition, both the sda and the scl pins are monitored. if the sda pin is already low, or the scl pin is already low, then all of the following occur: the start condition is aborted, the bclif flag is set and the mssp module is reset to its idle state (figure 17-26). the start condition begins with the sda and scl pins deasserted. when the sda pin is sampled high, the baud rate generator is loaded from sspadd<6:0> and counts down to ? 0 ?. if the scl pin is sampled low while sda is high, a bus collision occurs, because it is assumed that another master is attempting to drive a data ? 1 ? during the start condition. if the sda pin is sampled low during this count, the brg is reset and the sda line is asserted early (figure 17-28). if, however, a ? 1 ? is sampled on the sda pin, the sda pin is asserted low at the end of the brg count. the baud rate generator is then reloaded and counts down to ? 0 ? and during this time, if the scl pin is sampled as ? 0 ?, a bus collision does not occur. at the end of the brg count, the scl pin is asserted low. figure 17-26: bus collision during start condition (sda only) note: the reason that bus collision is not a factor during a start condition is that no two bus masters can assert a start condition at the exact same time. therefore, one master will always assert sda before the other. this condition does not cause a bus colli- sion because the two masters must be allowed to arbitrate the first address fol- lowing the start condition. if the address is the same, arbitration must be allowed to continue into the data portion, repeated start or stop conditions. sda scl sen sda sampled low before sda goes low before the sen bit is set. s bit and sspif set because ssp module reset into idle state. sen cleared automatically because of bus collision. s bit and sspif set because set sen, enable start condition if sda = 1 , scl = 1 sda = 0 , scl = 1 . bclif s sspif sda = 0 , scl = 1 . sspif and bclif are cleared in software sspif and bclif are cleared in software set bclif, start condition. set bclif.
? 2004 microchip technology inc. ds39609b-page 193 pic18f6520/8520/6620/8620/6720/8720 figure 17-27: bus collision d uring start condition (scl = 0 ) figure 17-28: brg reset due to sda arbitrat ion during start condition sda scl sen bus collision occurs. set bclif. scl = 0 before sda = 0 , set sen, enable start sequence if sda = 1 , scl = 1 t brg t brg sda = 0 , scl = 1 bclif s sspif interrupt cleared in software bus collision occurs. set bclif. scl = 0 before brg time-out, ? 0 ?? 0 ? ? 0 ? ? 0 ? sda scl sen set s set sen, enable start sequence if sda = 1 , scl = 1 less than t brg t brg sda = 0 , scl = 1 bclif s sspif s interrupts cleared in software set sspif sda = 0 , scl = 1 scl pulled low after brg time-out set sspif ? 0 ? sda pulled low by other master. reset brg and assert sda.
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 194 ? 2004 microchip technology inc. 17.4.17.2 bus collision during a repeated start condition during a repeated start condition, a bus collision occurs if: a) a low level is sampled on sda when scl goes from low level to high level. b) scl goes low before sda is asserted low, indicating that another master is attempting to transmit a data ? 1 ?. when the user deasserts sda and the pin is allowed to float high, the brg is loaded with sspadd<6:0> and counts down to ? 0 ?. the scl pin is then deasserted and when sampled high, the sda pin is sampled. if sda is low, a bus collision has occurred (i.e., another master is attempting to transmit a data ? 0 ?, figure 17-29). if sda is sampled high, the brg is reloaded and begins counting. if sda goes from high-to-low before the brg times out, no bus collision occurs because no two masters can assert sda at exactly the same time. if scl goes from high-to-low before the brg times out and sda has not already been asserted, a bus collision occurs. in this case, another master is attempting to transmit a data ? 1 ? during the repeated start condition, figure 17-30. if, at the end of the brg time-out, both scl and sda are still high, the sda pin is driven low and the brg is reloaded and begins counting. at the end of the count, regardless of the status of the scl pin, the scl pin is driven low and the repeated start condition is complete. figure 17-29: bus collision during a repeat ed start condition (case 1) figure 17-30: bus collision during repeat ed start condition (case 2) sda scl rsen bclif s sspif sample sda when scl goes high. if sda = 0 , set bclif and release sda and scl. cleared in software ? 0 ? ? 0 ? sda scl bclif rsen s sspif interrupt cleared in software scl goes low before sda, set bclif. release sda and scl. t brg t brg ? 0 ?
? 2004 microchip technology inc. ds39609b-page 195 pic18f6520/8520/6620/8620/6720/8720 17.4.17.3 bus collision during a stop condition bus collision occurs during a stop condition if: a) after the sda pin has been deasserted and allowed to float high, sda is sampled low after the brg has timed out. b) after the scl pin is deasserted, scl is sampled low before sda goes high. the stop condition begins with sda asserted low. when sda is sampled low, the scl pin is allowed to float. when the pin is sampled high (clock arbitration), the baud rate generator is loaded with sspadd<6:0> and counts down to ? 0 ?. after the brg times out, sda is sampled. if sda is sampled low, a bus collision has occurred. this is due to another master attempting to drive a data ? 0 ? (figure 17-31). if the scl pin is sampled low before sda is allowed to float high, a bus collision occurs. this is another case of another master attempting to drive a data ? 0 ? (figure 17-32). figure 17-31: bus collision during a stop condition (case 1) figure 17-32: bus collision during a stop condition (case 2) sda scl bclif pen p sspif t brg t brg t brg sda asserted low sda sampled low after t brg , set bclif ? 0 ? ? 0 ? sda scl bclif pen p sspif t brg t brg t brg assert sda scl goes low before sda goes high, set bclif ? 0 ? ? 0 ?
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 196 ? 2004 microchip technology inc. notes:
? 2004 microchip technology inc. ds39609b-page 197 pic18f6520/8520/6620/8620/6720/8720 18.0 addressable universal synchronous asynchronous receiver transmitter (usart) the universal synchronous asynchronous receiver transmitter (usart) module (also known as a serial communications interface or sci) is one of the two types of serial i/o modules available on pic18fxx20 devices. each device has two usarts, which can be configured independently of each other. each can be configured as a full-duplex asynchronous system that can communicate with peripheral devices, such as crt terminals and personal computers, or as a half- duplex synchronous system that can communicate with peripheral devices, such as a/d or d/a integrated circuits, serial eeproms, etc. the usart can be configured in the following modes: asynchronous (full-duplex) synchronous ? master (half-duplex) synchronous ? slave (half-duplex) the pins of usart1 and usart2 are multiplexed with the functions of portc (rc6/tx1/ck1 and rc7/rx1/ dt1) and portg (rg1/tx2/ck2 and rg2/rx2/dt2), respectively. in order to configure these pins as a usart: for usart1: - bit spen (rcsta1<7>) must be set (= 1 ) - bit trisc<7> must be set (= 1 ) - bit trisc<6> must be cleared (= 0 ) for asynchronous and synchronous master modes - bit trisc<6> must be set (= 1 ) for synchronous slave mode for usart2: - bit spen (rcsta2<7>) must be set (= 1 ) - bit trisg<2> must be set (= 1 ) - bit trisg<1> must be cleared (= 0 ) for asynchronous and synchronous master modes - bit trisc<6> must be set (= 1 ) for synchronous slave mode register 18-1 shows the layout of the transmit status and control registers (txstax) and register 18-2 shows the layout of the receive status and control registers (rcstax). usart1 and usart2 each have their own independent and distinct pairs of transmit and receive control registers, which are identical to each other apart from their names. similarly, each usart has its own distinct set of transmit, receive and baud rate registers. note: throughout this section, references to register and bit names that may be associ- ated with a specific usart module are referred to generically by the use of ?x? in place of the specific module number. thus, ?rcstax? might refer to the receive status register for either usart1 or usart2.
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 198 ? 2004 microchip technology inc. register 18-1: txstax: transmit status and control register r/w-0 r/w-0 r/w-0 r/w-0 u-0 r/w-0 r-1 r/w-0 csrc tx9 txen sync ?brghtrmttx9d bit 7 bit 0 bit 7 csrc: clock source select bit asynchronous mode: don?t care. synchronous mode: 1 = master mode (clock generated internally from brg) 0 = slave mode (clock from external source) bit 6 tx9 : 9-bit transmit enable bit 1 = selects 9-bit transmission 0 = selects 8-bit transmission bit 5 txen : transmit enable bit 1 = transmit enabled 0 = transmit disabled note: sren/cren overrides txen in sync mode. bit 4 sync : usart mode select bit 1 = synchronous mode 0 = asynchronous mode bit 3 unimplemented: read as ? 0 ? bit 2 brgh : high baud rate select bit asynchronous mode: 1 = high speed 0 = low speed synchronous mode: unused in this mode. bit 1 trmt : transmit shift register status bit 1 = tsr empty 0 = tsr full bit 0 tx9d: 9th bit of transmit data can be address/data bit or a parity bit. legend: r = readable bit w = writable bit u = unimplemented bit, read as ?0? - n = value at por ?1? = bit is set ?0? = bit is cleared x = bit is unknown
? 2004 microchip technology inc. ds39609b-page 199 pic18f6520/8520/6620/8620/6720/8720 register 18-2: rcstax: receive status and control register r/w-0 r/w-0 r/w-0 r/w-0 r/w-0 r-0 r-0 r-x spen rx9 sren cren adden ferr oerr rx9d bit 7 bit 0 bit 7 spen: serial port enable bit 1 = serial port enabled (configures rx/dt and tx/ck pins as serial port pins) 0 = serial port disabled bit 6 rx9 : 9-bit receive enable bit 1 = selects 9-bit reception 0 = selects 8-bit reception bit 5 sren : single receive enable bit asynchronous mode : don?t care. synchronous mode ? m aster: 1 = enables single receive 0 = disables single receive this bit is cleared after reception is complete. synchronous mode ? slave: don?t care. bit 4 cren : continuous receive enable bit asynchronous mode: 1 = enables receiver 0 = disables receiver synchronous mode: 1 = enables continuous receive until enable bit cren is cleared (cren overrides sren) 0 = disables continuous receive bit 3 adden : address detect enable bit asynchronous mode 9-bit (rx9 = 1 ): 1 = enables address detection, enables interrupt and load of the receive buffer when rsr<8> is set 0 = disables address detection, all bytes are received and ninth bit can be used as parity bit bit 2 ferr : framing error bit 1 = framing error (can be updated by reading rcreg register and receive next valid byte) 0 = no framing error bit 1 oerr : overrun error bit 1 = overrun error (can be cleared by clearing bit cren) 0 = no overrun error bit 0 rx9d: 9th bit of received data this can be address/data bit or a parity bit and must be calculated by user firmware. legend: r = readable bit w = writable bit u = unimplemented bit, read as ?0? - n = value at por ?1? = bit is set ?0? = bit is cleared x = bit is unknown
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 200 ? 2004 microchip technology inc. 18.1 usart baud rate generator (brg) the brg supports both the asynchronous and synchronous modes of the usarts. it is a dedicated 8-bit baud rate generator. the spbrg register controls the period of a free running 8-bit timer. in asyn- chronous mode, bit brgh (txstax<2>) also controls the baud rate. in synchronous mode, bit brgh is ignored. table 18-1 shows the formula for computation of the baud rate for different usart modes, which only apply in master mode (internal clock). given the desired baud rate and f osc , the nearest integer value for the spbrgx register can be calcu- lated using the formula in table 18-1. from this, the error in baud rate can be determined. example 18-1 shows the calculation of the baud rate error for the following conditions: f osc = 16 mhz desired baud rate = 9600 brgh = 0 sync = 0 it may be advantageous to use the high baud rate (brgh = 1 ) even for slower baud clocks. this is because the equation in example 18-1 can reduce the baud rate error in some cases. writing a new value to the spbrgx register causes the brg timer to be reset (or cleared). this ensures the brg does not wait for a timer overflow before outputting the new baud rate. 18.1.1 sampling the data on the rxx pin (either rc7/rx1/dt1 or rg2/ rx2/dt2) is sampled three times by a majority detect circuit to determine if a high or a low level is present at the pin. example 18-1: calculating baud rate error table 18-1: baud rate formula table 18-2: registers associated with baud rate generator sync brgh = 0 (low speed) brgh = 1 (high speed) 0 1 (asynchronous) baud rate = f osc /(64(x + 1)) (synchronous) baud rate = f osc /(4(x + 1)) baud rate = f osc /(16(x + 1)) n/a legend: x = value in spbrgx (0 to 255) name bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 value on por, bor value on all other resets txstax csrc tx9 txen sync ?brgh trmt tx9d 0000 -010 0000 -010 rcstax spen rx9 sren cren adden ferr oerr rx9d 0000 000x 0000 000x spbrgx baud rate generator register 0000 0000 0000 0000 legend: x = unknown, ? = unimplemented, read as ? 0 ?. shaded cells are not used by the brg. note 1: register names generically refer to both of the identically named registers for the two usart modules, where ?x? indicates the particular module. bit names and reset values are identical between modules. desired baud rate = f osc /(64 (x + 1)) solving for x: x = ((f osc /desired baud rate)/64 ) ? 1 x = ((16000000/9600)/64) ? 1 x = [25.042] = 25 calculated baud rate = 16000000/(64 (25 + 1)) = 9615 error = (calculated baud rate ? desired baud rate) desired baud rate = (9615 ? 9600)/9600 = 0.16%
? 2004 microchip technology inc. ds39609b-page 201 pic18f6520/8520/6620/8620/6720/8720 table 18-3: baud rates for synchronous mode baud rate (kbps) f osc = 40 mhz 33 mhz 25 mhz 20 mhz kbaud % error spbrg value (decimal) kbaud % error spbrg value (decimal) kbaud % error spbrg value (decimal) kbaud % error spbrg value (decimal) 0.3 na - - na - - na - - na - - 1.2 na - - na - - na - - na - - 2.4 na - - na - - na - - na - - 9.6 na - - na - - na - - na - - 19.2 na - - na - - na - - na - - 76.8 76.92 +0.16 129 77.10 +0.39 106 77.16 +0.47 80 76.92 +0.16 64 96 96.15 +0.16 103 95.93 -0.07 85 96.15 +0.16 64 96.15 +0.16 51 300 303.03 +1.01 32 294.64 -1.79 27 297.62 -0.79 20 294.12 -1.96 16 500 500 0 19 485.30 -2.94 16 480.77 -3.85 12 500 0 9 high 10000 - 0 8250 - 0 6250 - 0 5000 - 0 low 39.06 - 255 32.23 - 255 24.41 - 255 19.53 - 255 baud rate (kbps) f osc = 16 mhz 10 mhz 7.15909 mhz 5.0688 mhz kbaud % error spbrg value (decimal) kbaud % error spbrg value (decimal) kbaud % error spbrg value (decimal) kbaud % error spbrg value (decimal) 0.3na- - na- - na - - na- - 1.2na- - na- - na - - na- - 2.4na- - na- - na - - na- - 9.6 na - - na - - 9.62 +0.23 185 9.60 0 131 19.2 19.23 +0.16 207 19.23 +0.16 129 19.24 +0.23 92 19.20 0 65 76.8 76.92 +0.16 51 75.76 -1.36 32 77.82 +1.32 22 74.54 -2.94 16 96 95.24 -0.79 41 96.15 +0.16 25 94.20 -1.88 18 97.48 +1.54 12 300 307.70 +2.56 12 312.50 +4.17 7 298.35 -0.57 5 316.80 +5.60 3 500 500 0 7 500 0 4 447.44 -10.51 3 422.40 -15.52 2 high 4000 - 0 2500 - 0 1789.80 - 0 1267.20 - 0 low 15.63 - 255 9.77 - 255 6.99 - 255 4.95 - 255 baud rate (kbps) f osc = 4 mhz 3.579545 mhz 1 mhz 32.768 khz kbaud % error spbrg value (decimal) kbaud % error spbrg value (decimal) kbaud % error spbrg value (decimal) kbaud % error spbrg value (decimal) 0.3 na - - na - - na - - 0.30 +1.14 26 1.2 na - - na - - 1.20 +0.16 207 1.17 -2.48 6 2.4 na - - na - - 2.40 +0.16 103 2.73 +13.78 2 9.6 9.62 +0.16 103 9.62 +0.23 92 9.62 +0.16 25 8.20 -14.67 0 19.2 19.23 +0.16 51 19.04 -0.83 46 19.23 +0.16 12 na - - 76.8 76.92 +0.16 12 74.57 -2.90 11 83.33 +8.51 2 na - - 96 1000 +4.17 9 99.43 +3.57 8 83.33 -13.19 2 na - - 300 333.33 +11.11 2 298.30 -0.57 2 250 -16.67 0 na - - 500 500 0 1 447.44 -10.51 1 na - - na - - high 1000 - 0 894.89 - 0 250 - 0 8.20 - 0 low 3.91 - 255 3.50 - 255 0.98 - 255 0.03 - 255
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 202 ? 2004 microchip technology inc. table 18-4: baud rates for asynchronous mode (brgh = 0 ) baud rate (kbps) f osc = 40 mhz 33 mhz 25 mhz 20 mhz kbaud % error spbrg value (decimal) kbaud % error spbrg value (decimal) kbaud % error spbrg value (decimal) kbaud % error spbrg value (decimal) 0.3 na - - na - - na - - na - - 1.2 na - - na - - na - - na - - 2.4 na - - 2.40 -0.07 214 2.40 -0.15 162 2.40 +0.16 129 9.6 9.62 +0.16 64 9.55 -0.54 53 9.53 -0.76 40 9.47 -1.36 32 19.2 18.94 -1.36 32 19.10 -0.54 26 19.53 +1.73 19 19.53 +1.73 15 76.8 78.13 +1.73 7 73.66 -4.09 6 78.13 +1.73 4 78.13 +1.73 3 96 89.29 -6.99 6 103.13 +7.42 4 97.66 +1.73 3 104.17 +8.51 2 300 312.50 +4.17 1 257.81 -14.06 1 na - - 312.50 +4.17 0 500 625 +25.00 0 na - - na - - na - - high 625 - 0 515.63 - 0 390.63 - 0 312.50 - 0 low 2.44 - 255 2.01 - 255 1.53 - 255 1.22 - 255 baud rate (kbps) f osc = 16 mhz 10 mhz 7.15909 mhz 5.0688 mhz kbaud % error spbrg value (decimal) kbaud % error spbrg value (decimal) kbaud % error spbrg value (decimal) kbaud % error spbrg value (decimal) 0.3 na - - na - - na - - na - - 1.2 1.20 +0.16 207 1.20 +0.16 129 1.20 +0.23 92 1.20 0 65 2.4 2.40 +0.16 103 2.40 +0.16 64 2.38 -0.83 46 2.40 0 32 9.6 9.62 +0.16 25 9.77 +1.73 15 9.32 -2.90 11 9.90 +3.13 7 19.2 19.23 +0.16 12 19.53 +1.73 7 18.64 -2.90 5 19.80 +3.13 3 76.8 83.33 +8.51 2 78.13 +1.73 1 111.86 +45.65 0 79.20 +3.13 0 96 83.33 -13.19 2 78.13 -18.62 1 na - - na - - 300 250 -16.67 0 156.25 -47.92 0 na - - na - - 500 na - - na - - na - - na - - high 250 - 0 156.25 - 0 111.86 - 0 79.20 - 0 low 0.98 - 255 0.61 - 255 0.44 - 255 0.31 - 255 baud rate (kbps) f osc = 4 mhz 3.579545 mhz 1 mhz 32.768 khz kbaud % error spbrg value (decimal) kbaud % error spbrg value (decimal) kbaud % error spbrg value (decimal) kbaud % error spbrg value (decimal) 0.3 0.30 -0.16 207 0.30 +0.23 185 0.30 +0.16 51 0.26 -14.67 1 1.2 1.20 +1.67 51 1.19 -0.83 46 1.20 +0.16 12 na - - 2.4 2.40 +1.67 25 2.43 +1.32 22 2.23 -6.99 6 na - - 9.6 8.93 -6.99 6 9.32 -2.90 5 7.81 -18.62 1 na - - 19.2 20.83 +8.51 2 18.64 -2.90 2 15.63 -18.62 0 na - - 76.8 62.50 -18.62 0 55.93 -27.17 0 na - - na - - 96 na - - na - - na - - na - - 300 na - - na - - na - - na - - 500 na - - na - - na - - na - - high 62.50 - 0 55.93 - 0 15.63 - 0 0.51 - 0 low 0.24 - 255 0.22 - 255 0.06 - 255 0.002 - 255
? 2004 microchip technology inc. ds39609b-page 203 pic18f6520/8520/6620/8620/6720/8720 table 18-5: baud rates for asynchronous mode (brgh = 1 ) baud rate (kbps) f osc = 40 mhz 33 mhz 25 mhz 20 mhz kbaud % error spbrg value (decimal) kbaud % error spbrg value (decimal) kbaud % error spbrg value (decimal) kbaud % error spbrg value (decimal) 0.3na- -na- -na- -na- - 1.2na- -na- -na- -na- - 2.4na- -na- -na- -na- - 9.6 na - - 9.60 -0.07 214 9.59 -0.15 162 9.62 +0.16 129 19.2 19.23 +0.16 129 19.28 +0.39 106 19.30 +0.47 80 19.23 +0.16 64 76.8 75.76 -1.36 32 76.39 -0.54 26 78.13 +1.73 19 78.13 +1.73 15 96 96.15 +0.16 25 98.21 +2.31 20 97.66 +1.73 15 96.15 +0.16 12 300 312.50 +4.17 7 294.64 -1.79 6 312.50 +4.17 4 312.50 +4.17 3 500 500 0 4 515.63 +3.13 3 520.83 +4.17 2 416.67 -16.67 2 high 2500 - 0 2062.50 - 0 1562.50 - 0 1250 - 0 low 9.77 - 255 8,06 - 255 6.10 - 255 4.88 - 255 baud rate (kbps) f osc = 16 mhz 10 mhz 7.15909 mhz 5.0688 mhz kbaud % error spbrg value (decimal) kbaud % error spbrg value (decimal) kbaud % error spbrg value (decimal) kbaud % error spbrg value (decimal) 0.3na- - na- - na- - na- - 1.2na- - na- - na- - na- - 2.4 na - - na - - 2.41 +0.23 185 2.40 0 131 9.6 9.62 +0.16 103 9.62 +0.16 64 9.52 -0.83 46 9.60 0 32 19.2 19.23 +0.16 51 18.94 -1.36 32 19.45 +1.32 22 18.64 -2.94 16 76.8 76.92 +0.16 12 78.13 +1.73 7 74.57 -2.90 5 79.20 +3.13 3 96 100 +4.17 9 89.29 -6.99 6 89.49 -6.78 4 105.60 +10.00 2 300 333.33 +11.11 2 312.50 +4.17 1 447.44 +49.15 0 316.80 +5.60 0 500 500 0 1 625 +25.00 0 447.44 -10.51 0 na - - high 1000 - 0 625 - 0 447.44 - 0 316.80 - 0 low 3.91 - 255 2.44 - 255 1.75 - 255 1.24 - 255 baud rate (kbps) f osc = 4 mhz 3.579545 mhz 1 mhz 32.768 khz kbaud % error spbrg value (decimal) kbaud % error spbrg value (decimal) kbaud % error spbrg value (decimal) kbaud % error spbrg value (decimal) 0.3 na - - na - - 0.30 +0.16 207 0.29 -2.48 6 1.2 1.20 +0.16 207 1.20 +0.23 185 1.20 +0.16 51 1.02 -14.67 1 2.4 2.40 +0.16 103 2.41 +0.23 92 2.40 +0.16 25 2.05 -14.67 0 9.6 9.62 +0.16 25 9.73 +1.32 22 8.93 -6.99 6 na - - 19.2 19.23 +0.16 12 18.64 -2.90 11 20.83 +8.51 2 na - - 76.8 na - - 74.57 -2.90 2 62.50 -18.62 0 na - - 96 na - - 111.86 +16.52 1 na - - na - - 300 na - - 223.72 -25.43 0 na - - na - - 500na- - na- - na- - na- - high 250 - 0 55.93 - 0 62.50 - 0 2.05 - 0 low 0.98 - 255 0.22 - 255 0.24 - 255 0.008 - 255
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 204 ? 2004 microchip technology inc. 18.2 usart asynchronous mode in this mode, the usarts use standard non-return-to- zero (nrz) format (one start bit, eight or nine data bits and one stop bit). the most common data format is 8 bits. an on-chip dedicated 8-bit baud rate generator can be used to derive standard baud rate frequencies from the oscillator. the usart transmits and receives the lsb first. the usart?s transmitter and receiver are functionally independent, but use the same data format and baud rate. the baud rate generator produces a clock, either 16 or 64 times the bit shift rate, depending on bit brgh (txstax<2>). parity is not supported by the hardware, but can be implemented in software (and stored as the ninth data bit). asynchronous mode is stopped during sleep. asynchronous mode is selected by clearing bit sync (txstax<4>). the usart asynchronous module consists of the following important elements: baud rate generator sampling circuit asynchronous transmitter asynchronous receiver 18.2.1 usart asynchronous transmitter the usart transmitter block diagram is shown in figure 18-1. the heart of the transmitter is the transmit (serial) shift register (tsr). the shift register obtains its data from the read/write transmit buffer register, txregx. the txregx register is loaded with data in software. the tsr register is not loaded until the stop bit has been transmitted from the previous load. as soon as the stop bit is transmitted, the tsr is loaded with new data from the txregx register (if available). once the txregx register transfers the data to the tsr register (occurs in one t cy ), the txregx register is empty and flag bit, txx1if (pir1<4> for usart1, pir3<4> for usart2), is set. this interrupt can be enabled/disabled by setting/clearing enable bit, txxie (pie1<4> for usart1, pie<4> for usart2). flag bit txxif will be set, regardless of the state of enable bit txxie and cannot be cleared in software. it will reset only when new data is loaded into the txregx register. while flag bit txif indicates the status of the txregx register, another bit, trmt (txstax<1>), shows the status of the tsr register. status bit trmt is a read-only bit, which is set when the tsr register is empty. no interrupt logic is tied to this bit, so the user has to poll this bit in order to determine if the tsr register is empty. to set up an asynchronous transmission: 1. initialize the spbrgx register for the appropri- ate baud rate. if a high-speed baud rate is desired, set bit brgh ( section 18.1 ?usart baud rate generator (brg)? ). 2. enable the asynchronous serial port by clearing bit sync and setting bit spen. 3. if interrupts are desired, set enable bit txxie in the appropriate pie register. 4. if 9-bit transmission is desired, set transmit bit tx9. can be used as address/data bit. 5. enable the transmission by setting bit txen, which will also set bit txxif. 6. if 9-bit transmission is selected, the ninth bit should be loaded in bit tx9d. 7. load data to the txregx register (starts transmission). figure 18-1: usart transmit block diagram note 1: the tsr register is not mapped in data memory, so it is not available to the user. 2: flag bit txif is set when enable bit txen is set. note: txif is not cleared immediately upon loading data into the transmit buffer txreg. the flag bit becomes valid in the second instruction cycle following the load instruction. txif txie interrupt txen baud rate clk spbrg baud rate generator tx9d msb lsb data bus txreg register tsr register (8) 0 tx9 trmt spen tx pin pin buffer and control 8 ? ? ?
? 2004 microchip technology inc. ds39609b-page 205 pic18f6520/8520/6620/8620/6720/8720 figure 18-2: asynchronous transmission figure 18-3: asynchronous transmiss ion (back to back) table 18-6: registers associated with asynchronous transmission word 1 stop bit word 1 transmit shift reg start bit bit 0 bit 1 bit 7/8 write to txreg word 1 brg output (shift clock) rc6/tx1/ck1 (pin) txif bit (transmit buffer reg. empty flag) trmt bit (transmit shift reg. empty flag) transmit shift reg. write to txreg brg output (shift clock) rc6/tx1/ck1 (pin) txif bit (interrupt reg. flag) trmt bit (transmit shift reg. empty flag) word 1 word 2 word 1 word 2 start bit stop bit start bit transmit shift reg. word 1 word 2 bit 0 bit 1 bit 7/8 bit 0 note: this timing diagram shows two consecutive transmissions. name bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 value on por, bor value on all other resets intcon gie/gieh peie/giel tmr0ie int0ie rbie tmr0if int0if rbif 0000 0000 0000 0000 pir1 pspif adif rc1if tx1if sspif ccp1if tmr2if tmr1if 0000 0000 0000 0000 pie1 pspie adie rc1ie tx1ie sspie ccp1ie tmr2ie tmr1ie 0000 0000 0000 0000 ipr1 pspip adip rc1ip tx1ip sspip ccp1ip tmr2ip tmr1ip 0111 1111 0111 1111 pir3 ? ? rc2if tx2if tmr4if ccp5if ccp4if ccp3if --00 0000 --00 0000 pie3 ? ? rc2ie tx2ie tmr4ie ccp5ie ccp4ie ccp3ie --00 0000 --00 0000 ipr3 ? ? rc2ip tx2ip tmr4ip ccp5ip ccp4ip ccp3ip --11 1111 --11 1111 rcstax (1) spen rx9 sren cren adden ferr oerr rx9d 0000 000x 0000 000x txregx (1) usart transmit register 0000 0000 0000 0000 txstax (1) csrc tx9 txen sync ? brgh trmt tx9d 0000 -010 0000 -010 spbrgx (1) baud rate generator register 0000 0000 0000 0000 legend: x = unknown, ? = unimplemented locations read as ? 0 ?. shaded cells are not used for asynchronous transmission. note 1: register names generically refer to both of the identica lly named registers for the tw o usart modules, where ?x? indicates the particular module. bit names and reset values are identical between modules.
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 206 ? 2004 microchip technology inc. 18.2.2 usart asynchronous receiver the usart receiver block diagram is shown in figure 18-4. the data is received on the pin (rc7/rx1/ dt1 or rg2/rx2/dt2) and drives the data recovery block. the data recovery block is actually a high-speed shifter operating at 16 times the baud rate, whereas the main receive serial shifter operates at the bit rate or at f osc . this mode would typically be used in rs-232 systems. to set up an asynchronous reception: 1. initialize the spbrg register for the appropriate baud rate. if a high-speed baud rate is desired, set bit brgh ( section 18.1 ?usart baud rate generator (brg)? ). 2. enable the asynchronous serial port by clearing bit sync and setting bit spen. 3. if interrupts are desired, set enable bit rcxie. 4. if 9-bit reception is desired, set bit rx9. 5. enable the reception by setting bit cren. 6. flag bit rcxif will be set when reception is com- plete and an interrupt will be generated if enable bit rcxie was set. 7. read the rcstax register to get the ninth bit (if enabled) and determine if any error occurred during reception. 8. read the 8-bit received data by reading the rcreg register. 9. if any error occurred, clear the error by clearing enable bit cren. 10. if using interrupts, ensure that the gie and peie bits in the intcon register (intcon<7:6>) are set. 18.2.3 setting up 9-bit mode with address detect this mode would typically be used in rs-485 systems. to set up an asynchronous reception with address detect enable: 1. initialize the spbrgx register for the appropri- ate baud rate. if a high-speed baud rate is required, set the brgh bit. 2. enable the asynchronous serial port by clearing the sync bit and setting the spen bit. 3. if interrupts are required, set the rcen bit and select the desired priority level with the rcip bit. 4. set the rx9 bit to enable 9-bit reception. 5. set the adden bit to enable address detect. 6. enable reception by setting the cren bit. 7. the rcxif bit will be set when reception is complete. the interrupt will be acknowledged if the rcxie and gie bits are set. 8. read the rcstax register to determine if any error occurred during reception, as well as read bit 9 of data (if applicable). 9. read rcregx to determine if the device is being addressed. 10. if any error occurred, clear the cren bit. 11. if the device has been addressed, clear the adden bit to allow all received data into the receive buffer and interrupt the cpu. figure 18-4: usart receive block diagram x64 baud rate clk spbrg baud rate generator rx pin pin buffer and control spen data recovery cren oerr ferr rsr register msb lsb rx9d rcreg register fifo interrupt rcif rcie data bus 8 64 16 or stop start (8) 7 1 0 rx9 ? ? ?
? 2004 microchip technology inc. ds39609b-page 207 pic18f6520/8520/6620/8620/6720/8720 figure 18-5: asynchronous reception table 18-7: registers associated with asynchronous reception start bit bit 7/8 bit 1 bit 0 bit 7/8 bit 0 stop bit start bit start bit bit 7/8 stop bit rx (pin) reg rcv buffer reg rcv shift read rcv buffer reg rcreg rcif (interrupt flag) oerr bit cren word 1 rcreg word 2 rcreg stop bit note: this timing diagram shows three words appearing on the rx input. the rcreg (receive buffer) is read after the third word, causing the oerr (overrun) bit to be set. name bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 value on por, bor value on all other resets intcon gie/ gieh peie/ giel tmr0ie int0ie rbie tmr0if int0if rbif 0000 0000 0000 0000 pir1 pspif adif rc1if txif sspif ccp1if tmr2if tmr1if 0000 0000 0000 0000 pie1 pspie adie rc1ie txie sspie ccp1ie tmr2ie tmr1ie 0000 0000 0000 0000 ipr1 pspip adip rc1ip txip sspip ccp1ip tmr2ip tmr1ip 0111 1111 0111 1111 pir3 ? ? rc2if tx2if tmr4if ccp5if ccp4if ccp3if --00 0000 --00 0000 pie3 ? ? rc2ie tx2ie tmr4ie ccp5ie ccp4ie ccp3ie --00 0000 --00 0000 ipr3 ? ? rc2ip tx2ip tmr4ip ccp5ip ccp4ip ccp3ip --11 1111 --11 1111 rcstax (1) spen rx9 sren cren adden ferr oerr rx9d 0000 000x 0000 000x rcregx (1) usart receive register 0000 0000 0000 0000 txstax (1) csrc tx9 txen sync ?brgh trmt tx9d 0000 -010 0000 -010 spbrgx (1) baud rate generator register 0000 0000 0000 0000 legend: x = unknown, ? = unimplemented locations read as ? 0 ?. shaded cells are not used for asynchronous reception. note 1: register names generically refer to both of the identica lly named registers for the tw o usart modules, where ?x? indicates the particular module. bit names and reset values are identical between modules.
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 208 ? 2004 microchip technology inc. 18.3 usart synchronous master mode in synchronous master mode, the data is transmitted in a half-duplex manner (i.e., transmission and reception do not occur at the same time). when transmitting data, the reception is inhibited and vice versa. synchronous mode is entered by setting bit sync (txstax<4>). in addition, enable bit spen (rcstax<7>) is set in order to configure the appropriate i/o pins to ck (clock) and dt (data) lines, respectively. the master mode indi- cates that the processor transmits the master clock on the ck line. the master mode is entered by setting bit csrc (txstax<7>). 18.3.1 usart synchronous master transmission the usart transmitter block diagram is shown in figure 18-1. the heart of the transmitter is the transmit (serial) shift register (tsr). the shift register obtains its data from the read/write transmit buffer register, txreg. the txregx register is loaded with data in software. the tsr register is not loaded until the last bit has been transmitted from the previous load. as soon as the last bit is transmitted, the tsr is loaded with new data from the txregx (if available). once the txregx register transfers the data to the tsr register (occurs in one t cycle ), the txregx is empty and interrupt bit txxif (pir1<4> for usart1, pir3<4> for usart2) is set. the interrupt can be enabled/disabled by setting/clearing enable bit txxie (pie1<4> for usart1, pie3<4> for usart2). flag bit txxif will be set, regardless of the state of enable bit txxie and can- not be cleared in software. it will reset only when new data is loaded into the txregx register. while flag bit txxif indicates the status of the txregx register, another bit trmt (txstax<1>) shows the status of the tsr register. trmt is a read-only bit, which is set when the tsr is empty. no interrupt logic is tied to this bit, so the user has to poll this bit in order to determine if the tsr register is empty. the tsr is not mapped in data memory, so it is not available to the user. to set up a synchronous master transmission: 1. initialize the spbrg register for the appropriate baud rate ( section 18.1 ?usart baud rate generator (brg)? ). 2. enable the synchronous master serial port by setting bits sync, spen and csrc. 3. if interrupts are desired, set enable bit txxie in the appropriate pie register. 4. if 9-bit transmission is desired, set bit tx9. 5. enable the transmission by setting bit txen. 6. if 9-bit transmission is selected, the ninth bit should be loaded in bit tx9d. 7. start transmission by loading data to the txregx register. table 18-8: registers associated with synchronous master transmission note: txif is not cleared immediately upon loading data into the transmit buffer txreg. the flag bit becomes valid in the second instruction cycle following the load instruction. name bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 value on por, bor value on all other resets intcon gie/ gieh peie/ giel tmr0ie int0ie rbie tmr0if int0if rbif 0000 0000 0000 0000 pir1 pspif adif rcif txif sspif ccp1if tmr2if tmr1if 0000 0000 0000 0000 pie1 pspie adie rcie txie sspie ccp1ie tmr2ie tmr1ie 0000 0000 0000 0000 ipr1 pspip adip rcip txip sspip ccp1ip tmr2ip tmr1ip 0111 1111 0111 1111 pir3 ? ? rc2if tx2if tmr4if ccp5if ccp4if ccp3if --00 0000 --00 0000 pie3 ? ? rc2ie tx2ie tmr4ie ccp5ie ccp4ie ccp3ie --00 0000 --00 0000 ipr3 ? ? rc2ip tx2ip tmr4ip ccp5ip ccp4ip ccp3ip --11 1111 --11 1111 rcstax (1) spen rx9 sren cren adden ferr oerr rx9d 0000 000x 0000 000x txregx (1) usart transmit register 0000 0000 0000 0000 txstax (1) csrc tx9 txen sync ? brgh trmt tx9d 0000 -010 0000 -010 spbrgx (1) baud rate generator register 0000 0000 0000 0000 legend: x = unknown, ? = unimplemented, read as ? 0 ?. shaded cells are not used for synchronous master transmission. note 1: register names generically refer to both of the identica lly named registers for the tw o usart modules, where ?x? indicates the particular module. bit names and reset values are identical between modules.
? 2004 microchip technology inc. ds39609b-page 209 pic18f6520/8520/6620/8620/6720/8720 figure 18-6: synchronous transmission figure 18-7: synchronous transmissi on (through txen) bit 0 bit 1 bit 7 word 1 q1 q2 q3q4 q1 q2 q3 q4 q1 q2q3 q4 q1 q2 q3 q4 q1 q2 q3 q4 q3q4 q1 q2 q3q4 q1 q2 q3 q4 q1q2 q3 q4 q1 q2 q3 q4 q1 q2 q3 q4 q1 q2q3 q4 bit 2 bit 0 bit 1 bit 7 rc7/rx1/dt1 rc6/tx1/ck1 write to txreg reg txif bit (interrupt flag) trmt txen bit ? 1 ? ? 1 ? word 2 trmt bit write word 1 write word 2 note: sync master mode; spbrg = 0 . continuous transmission of two 8-bit words. pin pin rc7/rx1/dt1 pin rc6/tx1/ck1 pin write to txreg reg txif bit trmt bit bit 0 bit 1 bit 2 bit 6 bit 7 txen bit
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 210 ? 2004 microchip technology inc. 18.3.2 usart synchronous master reception once synchronous mode is selected, reception is enabled by setting either enable bit sren (rcstax<5>) or enable bit cren (rcstax<4>). data is sampled on the rxx pin (rc7/rx1/dt1 or rg2/rx2/ dt2) on the falling edge of the clock. if enable bit sren is set, only a single word is received. if enable bit cren is set, the reception is continuous until cren is cleared. if both bits are set, then cren takes precedence. to set up a synchronous master reception: 1. initialize the spbrgx register for the appropri- ate baud rate ( section 18.1 ?usart baud rate generator (brg)? ). 2. enable the synchronous master serial port by setting bits sync, spen and csrc. 3. ensure bits cren and sren are clear. 4. if interrupts are desired, set enable bit rcxie in the appropriate pie register. 5. if 9-bit reception is desired, set bit rx9. 6. if a single reception is required, set bit sren. for continuous reception, set bit cren. 7. interrupt flag bit rcxif will be set when reception is complete and an interrupt will be generated if the enable bit rcxie was set. 8. read the rcstax register to get the ninth bit (if enabled) and determine if any error occurred during reception. 9. read the 8-bit received data by reading the rcregx register. 10. if any error occurred, clear the error by clearing bit cren. 11. if using interrupts, ensure that the gie and peie bits in the intcon register (intcon<7:6>) are set. table 18-9: registers associated with synchronous master reception figure 18-8: synchronous reception (master mode, sren) name bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 value on por, bor value on all other resets intcon gie/gieh peie/giel tmr0ie int0ie rbie tmr0if int0if rbif 0000 0000 0000 0000 pir1 pspif adif rc1if tx1if sspif ccp1if tmr2if tmr1if 0000 0000 0000 0000 pie1 pspie adie rc1ie tx1ie sspie ccp1ie tmr2ie tmr1ie 0000 0000 0000 0000 ipr1 pspip adip rc1ip tx1ip sspip ccp1ip tmr2ip tmr1ip 0111 1111 0111 1111 pir3 ? ? rc2if tx2if tmr4if ccp5if ccp4if ccp3if --00 0000 --00 0000 pie3 ? ?rc2ie tx2ie tmr4ie ccp5ie ccp4ie ccp3ie --00 0000 --00 0000 ipr3 ? ?rc2ip tx2ip tmr4ip ccp5ip ccp4ip ccp3ip --11 1111 --11 1111 rcstax (1) spen rx9 sren cren adden ferr oerr rx9d 0000 000x 0000 000x rcregx (1) usart receive register 0000 0000 0000 0000 txstax (1) csrc tx9 txen sync ? brgh trmt tx9d 0000 -010 0000 -010 spbrgx (1) baud rate generator register 0000 0000 0000 0000 legend: x = unknown, ? = unimplemented, read as ? 0 ?. shaded cells are not used for synchronous master reception. note 1: register names generically refer to both of the identica lly named registers for the tw o usart modules, where ?x? indicates the particular module. bit names and reset values are identical between modules. cren bit rc7/rx1/dt1 pin rc6/tx1/ck1 pin write to bit sren sren bit rcif bit (interrupt) read rxreg q3 q4 q1 q2 q3 q4 q1 q2 q3 q4 q2 q1 q2 q3 q4 q1 q2 q3 q4 q1 q2 q3 q4 q1 q2 q3 q4 q1 q2 q3 q4 q1 q2 q3 q4 q1 q2 q3 q4 ? 0 ? bit 0 bit 1 bit 2 bit 3 bit 4 bit 5 bit 6 bit 7 ? 0 ? q1 q2 q3 q4 note: timing diagram demonstrates sync master mode with bit sren = 1 and bit brgh = 0 .
? 2004 microchip technology inc. ds39609b-page 211 pic18f6520/8520/6620/8620/6720/8720 18.4 usart synchronous slave mode synchronous slave mode differs from the master mode in the fact that the shift clock is supplied externally at the txx pin (rc6/tx1/ck1 or rg1/tx2/ck2), instead of being supplied internally in master mode. trisc<6> must be set for this mode. this allows the device to transfer or receive data while in sleep mode. slave mode is entered by clearing bit csrc (txstax<7>). 18.4.1 usart synchronous slave transmit the operation of the synchronous master and slave modes are identical, except in the case of the sleep mode. if two words are written to the txreg and then the sleep instruction is executed, the following will occur: a) the first word will immediately transfer to the tsr register and transmit. b) the second word will remain in txreg register. c) flag bit txxif will not be set. d) when the first word has been shifted out of tsr, the txregx register will transfer the second word to the tsr and flag bit txxif will now be set. e) if enable bit txxie is set, the interrupt will wake the chip from sleep. if the global interrupt is enabled, the program will branch to the interrupt vector. to set up a synchronous slave transmission: 1. enable the synchronous slave serial port by setting bits sync and spen and clearing bit csrc. 2. clear bits cren and sren. 3. if interrupts are desired, set enable bit txxie. 4. if 9-bit transmission is desired, set bit tx9. 5. enable the transmission by setting enable bit txen. 6. if 9-bit transmission is selected, the ninth bit should be loaded in bit tx9d. 7. start transmission by loading data to the txregx register. 8. if using interrupts, ensure that the gie and peie bits in the intcon register (intcon<7:6>) are set. table 18-10: registers associated with synchronous slave transmission name bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 value on por, bor value on all other resets intcon gie/ gieh peie/ giel tmr0ie int0ie rbie tmr0if int0if rbif 0000 0000 0000 0000 pir1 pspif adif rc1if tx1if sspif ccp1if tmr2if tmr1if 0000 0000 0000 0000 pie1 pspie adie rc1ie tx1ie sspie ccp1ie tmr2ie tmr1ie 0000 0000 0000 0000 ipr1 pspip adip rc1ip tx1ip sspip ccp1ip tmr2ip tmr1ip 0111 1111 0111 1111 pir3 ? ? rc2if tx2if tmr4if ccp5if ccp4if ccp3if --00 0000 --00 0000 pie3 ? ? rc2ie tx2ie tmr4ie ccp5ie ccp4ie ccp3ie --00 0000 --00 0000 ipr3 ? ? rc2ip tx2ip tmr4ip ccp5ip ccp4ip ccp3ip --11 1111 --11 1111 rcstax (1) spen rx9 sren cren adden ferr oerr rx9d 0000 000x 0000 000x txregx (1) usart transmit register 0000 0000 0000 0000 txstax (1) csrc tx9 txen sync ? brgh trmt tx9d 0000 -010 0000 -010 spbrgx (1) baud rate generator register 0000 0000 0000 0000 legend: x = unknown, ? = unimplemented, read as ? 0 ?. shaded cells are not used for synchronous slave transmission. note 1: register names generically refer to both of the identica lly named registers for the tw o usart modules, where ?x? indicates the particular module. bit names and reset values are identical between modules.
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 212 ? 2004 microchip technology inc. 18.4.2 usart synchronous slave reception the operation of the synchronous master and slave modes is identical, except in the case of the sleep mode and bit sren, which is a ?don?t care? in slave mode. if receive is enabled by setting bit cren prior to the sleep instruction, then a word may be received during sleep. on completely receiving the word, the rsr reg- ister will transfer the data to the rcreg register and if enable bit rcxie bit is set, the interrupt generated will wake the chip from sleep. if the global interrupt is enabled, the program will branch to the interrupt vector. to set up a synchronous slave reception: 1. enable the synchronous master serial port by setting bits sync and spen and clearing bit csrc. 2. if interrupts are desired, set enable bit rcxie. 3. if 9-bit reception is desired, set bit rx9. 4. to enable reception, set enable bit cren. 5. flag bit rcxif will be set when reception is complete. an interrupt will be generated if enable bit rcxie was set. 6. read the rcstax register to get the ninth bit (if enabled) and determine if any error occurred during reception. 7. read the 8-bit received data by reading the rcregx register. 8. if any error occurred, clear the error by clearing bit cren. 9. if using interrupts, ensure that the gie and peie bits in the intcon register (intcon<7:6>) are set. table 18-11: registers associated with synchronous slave reception name bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 value on por, bor value on all other resets intcon gie/ gieh peie/ giel tmr0ie int0ie rbie tmr0if int0if rbif 0000 0000 0000 0000 pir1 pspif adif rc1if tx1if sspif ccp1if tmr2if tmr1if 0000 0000 0000 0000 pie1 pspie adie rc1ie tx1ie sspie ccp1ie tmr2ie tmr1ie 0000 0000 0000 0000 ipr1 pspip adip rc1ip tx1ip sspip ccp1ip tmr2ip tmr1ip 0111 1111 0111 1111 pir3 ? ? rc2if tx2if tmr4if ccp5if ccp4if ccp3if --00 0000 --00 0000 pie3 ? ? rc2ie tx2ie tmr4ie ccp5ie ccp4ie ccp3ie --00 0000 --00 0000 ipr3 ? ? rc2ip tx2ip tmr4ip ccp5ip ccp4ip ccp3ip --11 1111 --11 1111 rcstax (1) spen rx9 sren cren adden ferr oerr rx9d 0000 000x 0000 000x rcregx (1) usart receive register 0000 0000 0000 0000 txstax (1) csrc tx9 txen sync ? brgh trmt tx9d 0000 -010 0000 -010 spbrgx (1) baud rate generator register 0000 0000 0000 0000 legend: x = unknown, ? = unimplemented, read as ? 0 ?. shaded cells are not used for synchronous slave reception. note 1: register names generically refer to both of the identica lly named registers for the tw o usart modules, where ?x? indicates the particular module. bit names and reset values are identical between modules.
? 2004 microchip technology inc. ds39609b-page 213 pic18f6520/8520/6620/8620/6720/8720 19.0 10-bit analog-to-digital converter (a/d) module the analog-to-digital (a/d) converter module has 12 inputs for the pic18f6x20 devices and 16 for the pic18f8x20 devices. this module allows conversion of an analog input signal to a corresponding 10-bit digital number. the module has five registers: a/d result high register (adresh) a/d result low register (adresl) a/d control register 0 (adcon0) a/d control register 1 (adcon1) a/d control register 2 (adcon2) the adcon0 register, shown in register 19-1, con- trols the operation of the a/d module. the adcon1 register, shown in register 19-2, configures the func- tions of the port pins. the adcon2 register, shown in register 19-3, configures the a/d clock source and justification. register 19-1: adcon0 register u-0 u-0 r/w-0 r/w-0 r/w-0 r/w-0 r/w-0 r/w-0 ? ? chs3 chs2 chs1 chs0 go/done adon bit 7 bit 0 bit 7-6 unimplemented: read as ? 0 ? bit 5-2 chs3:chs0: analog channel select bits 0000 = channel 0 (an0) 0001 = channel 1 (an1) 0010 = channel 2 (an2) 0011 = channel 3 (an3) 0100 = channel 4 (an4) 0101 = channel 5 (an5) 0110 = channel 6 (an6) 0111 = channel 7 (an7) 1000 = channel 8 (an8) 1001 = channel 9 (an9) 1010 = channel 10 (an10) 1011 = channel 11 (an11) 1100 = channel 12 (an12) (1) 1101 = channel 13 (an13) (1) 1110 = channel 14 (an14) (1) 1111 = channel 15 (an15) (1) note 1: these channels are not available on the pic18f6x20 (64-pin) devices. bit 1 go/done : a/d conversion status bit when adon = 1 : 1 = a/d conversion in progress (setting this bit starts the a/d conversion, which is automatically cleared by hardware when the a/d conversion is complete) 0 = a/d conversion not in progress bit 0 adon: a/d on bit 1 = a/d converter module is enabled 0 = a/d converter module is disabled legend: r = readable bit w = writable bit u = unimplemented bit, read as ?0? - n = value at por ?1? = bit is set ?0? = bit is cleared x = bit is unknown
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 214 ? 2004 microchip technology inc. register 19-2: adcon1 register u-0 u-0 r/w-0 r/w-0 r/w-0 r/w-0 r/w-0 r/w-0 ? ? vcfg1 vcfg0 pcfg3 pcfg2 pcfg1 pcfg0 bit 7 bit 0 bit 7-6 unimplemented: read as ? 0 ? bit 5-4 vcfg1:vcfg0: voltage reference configuration bits: bit 3-0 pcfg3:pcfg0: a/d port configuration control bits: legend: r = readable bit w = writable bit u = unimplemented bit, read as ?0? - n = value at por ?1? = bit is set ?0? = bit is cleared x = bit is unknown vcfg1 vcfg0 a/d v ref + a/d v ref - 00 av dd av ss 01 external v ref +av ss 10 av dd external v ref - 11 external v ref +external v ref - a = analog input d = digital i/o note: shaded cells indicate a/d channels available only on pic18f8x20 devices. pcfg3 pcfg0 an15 an14 an13 an12 an11 an10 an9 an8 an7 an6 an5 an4 an3 an2 an1 an0 0000 a a a aaaaaaaaaaaaa 0001 d d a aaaaaaaaaaaaa 0010 d d d aaaaaaaaaaaaa 0011 d d d daaaaaaaaaaaa 0100 d d d ddaaaaaaaaaaa 0101 d d d dddaaaaaaaaaa 0110 d d d ddddaaaaaaaaa 0111 d d d ddddda a a aaaaa 1000 d d d ddddddaaaaaaa 1001 d d d dddddddaaaaaa 1010 d d d ddddddddaaaaa 1011 d d d dddddddddaaaa 1100 d d d ddddddddddaaa 1101 d d d dddddddddddaa 1110 d d d dddddddddddda 1111 d d d ddddddddddddd
? 2004 microchip technology inc. ds39609b-page 215 pic18f6520/8520/6620/8620/6720/8720 register 19-3: adcon2 register the analog reference voltage is software selectable to either the device?s positive and negative supply voltage (v dd and v ss ), or the voltage level on the ra3/an3/ v ref + pin and ra2/an2/v ref - pin. the a/d converter has a unique feature of being able to operate while the device is in sleep mode. to oper- ate in sleep, the a/d conversion clock must be derived from the a/d?s internal rc oscillator. the output of the sample and hold is the input into the converter, which generates the result via successive approximation. a device reset forces all registers to their reset state. this forces the a/d module to be turned off and any conversion is aborted. each port pin associated with the a/d converter can be configured as an analog input (ra3 can also be a voltage reference), or as a digital i/o. the adresh and adresl registers contain the result of the a/d conversion. when the a/d conversion is complete, the result is loaded into the adresh/adresl registers, the go/done bit (adcon0 register) is cleared and a/d interrupt flag bit, adif, is set. the block diagram of the a/d module is shown in figure 19-1. r/w-0 u-0 u-0 u-0 u-0 r/w-0 r/w-0 r/w-0 adfm ? ? ? ? adcs2 adcs1 adcs0 bit 7 bit 0 bit 7 adfm: a/d result format select bit 1 = right justified 0 = left justified bit 6-3 unimplemented: read as ? 0 ? bit 2-0 adcs1:adcs0: a/d conversion clock select bits 000 = f osc /2 001 = f osc /8 010 = f osc /32 011 = f rc (clock derived from an rc oscillator = 1 mhz max) 100 = f osc /4 101 = f osc /16 110 = f osc /64 111 = f rc (clock derived from an rc oscillator = 1 mhz max) legend: r = readable bit w = writable bit u = unimplemented bit, read as ?0? - n = value at por ?1? = bit is set ?0? = bit is cleared x = bit is unknown
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 216 ? 2004 microchip technology inc. figure 19-1: a/d block diagram (input voltage) v ain v ref + reference voltage v dd vcfg1:vcfg0 chs3:chs0 an7 an6 an5 an4 an3 an2 an1 an0 0111 0110 0101 0100 0011 0010 0001 0000 10-bit converter v ref - v ss a/d an15 (1) an14 (1) an13 (1) an12 (1) an11 an10 an9 an8 1111 1110 1101 1100 1011 1010 1001 1000 note 1: channels an15 through an12 are not available on pic18f6x20 devices. 2: i/o pins have diode protection to v dd and v ss .
? 2004 microchip technology inc. ds39609b-page 217 pic18f6520/8520/6620/8620/6720/8720 the value in the adresh/adresl registers is not modified for a power-on reset. the adresh/ adresl registers will contain unknown data after a power-on reset. after the a/d module has been configured as desired, the selected channel must be acquired before the con- version is started. the analog input channels must have their corresponding tris bits selected as an input. to determine acquisition time, see section 19.1 ?a/d acquisition requirements? . after this acquisi- tion time has elapsed, the a/d conversion can be started. the following steps should be followed to do an a/d conversion: 1. configure the a/d module: configure analog pins, voltage reference and digital i/o (adcon1) select a/d input channel (adcon0) select a/d conversion clock (adcon2) turn on a/d module (adcon0) 2. configure a/d interrupt (if desired): clear adif bit set adie bit set gie bit 3. wait the required acquisition time. 4. start conversion: set go/done bit (adcon0 register) 5. wait for a/d conversion to complete, by either: polling for the go/done bit to be cleared or waiting for the a/d interrupt 6. read a/d result registers (adresh:adresl); clear bit adif, if required. 7. for the next conversion, go to step 1 or step 2, as required. the a/d conversion time per bit is defined as t ad . a minimum wait of 2 t ad is required before the next acquisition starts. figure 19-2: analog input model v ain c pin rs anx 5 pf v dd v t = 0.6v v t = 0.6v i leakage r ic 1k sampling switch ss r ss c hold = 120 pf v ss 6v sampling switch 5v 4v 3v 2v 567891011 (k ? ) v dd 500 na legend: c pin v t i leakage r ic ss c hold = input capacitance = threshold voltage = leakage current at the pin due to = interconnect resistance = sampling switch = sample/hold capacitance (from dac) various junctions = sampling switch resistance r ss
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 218 ? 2004 microchip technology inc. 19.1 a/d acquisition requirements for the a/d converter to meet its specified accuracy, the charge holding capacitor (c hold ) must be allowed to fully charge to the input channel voltage level. the analog input model is shown in figure 19-2. the source impedance (r s ) and the internal sampling switch (r ss ) impedance directly affect the time required to charge the capacitor c hold . the sampling switch (r ss ) impedance varies over the device voltage (v dd ). the source impedance affects the offset voltage at the analog input (due to pin leakage current). the maximum recommended impedance for analog sources is 2.5 k ? . after the analog input channel is selected (changed), this acquisition must be done before the conversion can be started. to calculate the minimum acquisition time, equation 19-1 may be used. this equation assumes that 1/2 lsb error is used (1024 steps for the a/d). the 1/2 lsb error is the maximum error allowed for the a/d to meet its specified resolution. example 19-1 shows the calculation of the minimum required acquisition time, t acq . this calculation is based on the following application system assumptions: c hold = 120 pf rs = 2.5 k ? conversion error 1/2 lsb v dd =5v rss = 7 k ? temperature = 50 c (system max.) v hold = 0v @ time = 0 equation 19-1: acquisition time equation 19-2: a/d minimum charging time example 19-1: calculating the minimum required acquisition time note: when the conversion is started, the holding capacitor is disconnected from the input pin. note: when using external voltage references with the a/d converter, the source impedance of the external voltage references must be less than 20 ? to obtain the a/d performance specified in parameters a01-a06. higher reference source impedances will increase both offset and gain errors. resistive voltage dividers will not provide a sufficiently low source impedance. to maintain the best possible performance in a/d conversions, external v ref inputs should be buffered with an operational amplifier or other low output impedance circuit. if deviating from the operating conditions specified for parameters a03-a06, the effect of parameter a50 (v ref input current) must be considered. t acq = amplifier settling time + holding capacitor charging time + temperature coefficient =t amp + t c + t coff v hold = (v ref ? (v ref /2048)) (1 ? e (-tc/c hold (r ic + r ss + r s )) ) or t c = -(120 pf)(1 k ? + r ss + r s ) ln(1/2047) t acq =t amp + t c + t coff temperature coefficient is only required for temperatures > 25 c. t acq =2 s + t c + [(temp ? 25 c)(0.05 s/ c)] t c =-c hold (r ic + r ss + r s ) ln(1/2047) -120 pf (1 k ? + 7 k ? + 2.5 k ? ) ln(0.0004885) -120 pf (10.5 k ? ) ln(0.0004885) -1.26 s (-7.6241) 9.61 s t acq =2 s + 9.61 s + [(50 c ? 25 c)(0.05 s/ c)] 11.61 s + 1.25 s 12.86 s
? 2004 microchip technology inc. ds39609b-page 219 pic18f6520/8520/6620/8620/6720/8720 19.2 selecting the a/d conversion clock the a/d conversion time per bit is defined as t ad . the a/d conversion requires 12 t ad per 10-bit conversion. the source of the a/d conversion clock is software selectable. there are seven possible options for t ad : 2 t osc 4 t osc 8 t osc 16 t osc 32 t osc 64 t osc internal rc oscillator for correct a/d conversions, the a/d conversion clock (t ad ) must be selected to ensure a minimum t ad time of 1.6 s. table 19-1 shows the resultant t ad times derived from the device operating frequencies and the a/d clock source selected. 19.3 configuring analog port pins the adcon1, trisa, trisf and trish registers control the operation of the a/d port pins. the port pins needed as analog inputs must have their correspond- ing tris bits set (input). if the tris bit is cleared (output), the digital output level (v oh or v ol ) will be converted. the a/d operation is independent of the state of the chs3:chs0 bits and the tris bits. table 19-1: t ad vs. device operating frequencies note 1: when reading the port register, all pins configured as analog input channels will read as cleared (a low level). pins config- ured as digital inputs will convert as an analog input. analog levels on a digitally configured input will not affect the conversion accuracy. 2: analog levels on any pin defined as a dig- ital input may cause the input buffer to consume current out of the device?s specification limits. ad clock source (t ad ) maximum device frequency operation adcs2:adcs0 pic18fxx20 pic18lfxx20 2 t osc 000 1.25 mhz 666 khz 4 t osc 100 2.50 mhz 1.33 mhz 8 t osc 001 5.00 mhz 2.67 mhz 16 t osc 101 10.0 mhz 5.33 mhz 32 t osc 010 20.0 mhz 10.67 mhz 64 t osc 110 40.0 mhz 21.33 mhz rc x11 ??
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 220 ? 2004 microchip technology inc. 19.4 a/d conversions figure 19-3 shows the operation of the a/d converter after the go bit has been set. clearing the go/done bit during a conversion will abort the current conver- sion. the a/d result register pair will not be updated with the partially completed a/d conversion sample. that is, the adresh:adresl registers will continue to contain the value of the last completed conversion (or the last value written to the adresh:adresl reg- isters). after the a/d conversion is aborted, a 2 t ad wait is required before the next acquisition is started. after this 2 t ad wait, acquisition on the selected channel is automatically started. 19.5 use of the ccp2 trigger an a/d conversion can be started by the ?special event trigger? of the ccp2 module. this requires that the ccp2m3:ccp2m0 bits (ccp2con<3:0>) be pro- grammed as ? 1011 ? and that the a/d module is enabled (adon bit is set). when the trigger occurs, the go/ done bit will be set, starting the a/d conversion and the timer1 (or timer3) counter will be reset to zero. timer1 (or timer3) is reset to automatically repeat the a/d acquisition period with minimal software overhead (moving adresh/adresl to the desired location). the appropriate analog input channel must be selected and the minimum acquisition done before the ?special event trigger? sets the go/done bit (starts a conversion). if the a/d module is not enabled (adon is cleared), the ?special event trigger? will be ignored by the a/d module, but will still reset the timer1 (or timer3) counter. figure 19-3: a/d conversion t ad cycles note: the go/done bit should not be set in the same instruction that turns on the a/d. t ad 1 t ad 2 t ad 3 t ad 4 t ad 5 t ad 6 t ad 7 t ad 8 t ad 11 set go bit holding capacitor is disconnected from analog input (typically 100 ns) b9 b8 b7 b6 b5 b4 b3 b2 t ad 9 t ad 10 b1 b0 t cy - t ad next q4: adresh/adresl is loaded, go bit is cleared, adif bit is set, holding capacitor is connected to analog input. conversion starts b0
? 2004 microchip technology inc. ds39609b-page 221 pic18f6520/8520/6620/8620/6720/8720 table 19-2: summary of a/d registers name bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 value on por, bor value on all other resets intcon gie/ gieh peie/ giel tmr0ie int0ie rbie tmr0if int0if rbif 0000 0000 0000 0000 pir1 pspif adif rcif txif sspif ccp1if tmr2if tmr1if 0000 0000 0000 0000 pie1 pspie adie rcie txie sspie ccp1ie tmr2ie tmr1ie 0000 0000 0000 0000 ipr1 pspip adip rcip txip sspip ccp1ip tmr2ip tmr1ip 0111 1111 0111 1111 pir2 ? cmif ? ? bclif lvdif tmr3if ccp2if -0-- 0000 -0-- 0000 pie2 ? cmie ? ? bclie lvdie tmr3ie ccp2ie -0-- 0000 -0-- 0000 ipr2 ? cmip ? ? bclip lvdip tmr3ip ccp2ip -0-- 0000 -0-- 0000 adresh a/d result register high byte xxxx xxxx uuuu uuuu adresl a/d result register low byte xxxx xxxx uuuu uuuu adcon0 ? ? chs3 chs3 chs1 chs0 go/done adon --00 0000 --00 0000 adcon1 ? ? vcfg1 vcfg0 pcfg3 pcfg2 pcfg1 pcfg0 --00 0000 --00 0000 adcon2 adfm ? ? ? ? adcs2 adcs1 adcs0 0--- -000 0--- -000 porta ? ra6 ra5 ra4 ra3 ra2 ra1 ra0 --0x 0000 --0u 0000 trisa ? porta data direction register --11 1111 --11 1111 portf rf7 rf6 rf5 rf4 rf3 rf2 rf1 rf0 x000 0000 u000 0000 latf latf7 latf6 latf5 latf4 latf3 latf2 latf1 latf0 xxxx xxxx uuuu uuuu trisf portf data direction control register 1111 1111 1111 1111 porth (1) rh7 rh6 rh5 rh4 rh3 rh2 rh1 rh0 0000 xxxx 0000 xxxx lath (1) lath7 lath6 lath5 lath4 lath3 lath2 lath1 lath0 xxxx xxxx uuuu uuuu trish (1) porth data direction control register 1111 1111 1111 1111 legend: x = unknown, u = unchanged, ? = unimplemented, read as ? 0 ?. shaded cells are not used for a/d conversion. note 1: only available on pic18f8x20 devices.
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 222 ? 2004 microchip technology inc. notes:
? 2004 microchip technology inc. ds39609b-page 223 pic18f6520/8520/6620/8620/6720/8720 20.0 comparator module the comparator module contains two analog compara- tors. the inputs to the comparators are multiplexed with the rf1 through rf6 pins. the on-chip voltage ref- erence ( section 21.0 ?comparator voltage reference module? ) can also be an input to the comparators. the cmcon register, shown as register 20-1, con- trols the comparator input and output multiplexers. a block diagram of the various comparator configurations is shown in figure 20-1. register 20-1: cmcon register r-0 r-0 r/w-0 r/w-0 r/w-0 r/w-0 r/w-0 r/w-0 c2out c1out c2inv c1inv cis cm2 cm1 cm0 bit 7 bit 0 bit 7 c2out : comparator 2 output bit when c2inv = 0 : 1 = c2 v in + > c2 v in - 0 = c2 v in + < c2 v in - when c2inv = 1 : 1 = c2 v in + < c2 v in - 0 = c2 v in + > c2 v in - bit 6 c1out : comparator 1 output bit when c1inv = 0 : 1 = c1 v in + > c1 v in - 0 = c1 v in + < c1 v in - when c1inv = 1 : 1 = c1 v in + < c1 v in - 0 = c1 v in + > c1 v in - bit 5 c2inv : comparator 2 output inversion bit 1 = c2 output inverted 0 = c2 output not inverted bit 4 c1inv : comparator 1 output inversion bit 1 = c1 output inverted 0 = c1 output not inverted bit 3 cis : comparator input switch bit when cm2:cm0 = 110 : 1 =c1 v in - connects to rf5/an10 c2 v in - connects to rf3/an8 0 =c1 v in - connects to rf6/an11 c2 v in - connects to rf4/an9 bit 2-0 cm2:cm0 : comparator mode bits figure 20-1 shows the comparator modes and the cm2:cm0 bit settings. legend: r = readable bit w = writable bit u = unimplemented bit, read as ?0? - n = value at por ?1? = bit is set ?0? = bit is cleared x = bit is unknown
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 224 ? 2004 microchip technology inc. 20.1 comparator configuration there are eight modes of operation for the compara- tors. the cmcon register is used to select these modes. figure 20-1 shows the eight possible modes. the trisf register controls the data direction of the comparator pins for each mode. if the comparator mode is changed, the comparator output level may not be valid for the specified mode change delay shown in the electrical specifications ( section 26.0 ?electrical characteristics? ). figure 20-1: comparator i/o operating modes note: comparator interrupts should be disabled during a comparator mode change. otherwise, a false interrupt may occur. c1 rf6/an11 v in - v in + rf5/an10 off (read as ? 0 ? ) comparators reset (por default value) a a cm2:cm0 = 000 c2 rf4/an9 v in - v in + rf3/an8 off (read as ? 0 ? ) a a c1 rf6/an11 v in - v in + rf5/an10 c1out two independent comparators a a cm2:cm0 = 010 c2 rf4/an9 v in - v in + rf3/an8 c2out a a c1 rf6/an11 v in - v in + rf5/an10 c1out two common reference comparators a a cm2:cm0 = 100 c2 rf4/an9 v in - v in + rf3/an8 c2out a d c2 rf4/an9 v in - v in + rf3/an8 off (read as ? 0 ? ) one independent comparator with output d d cm2:cm0 = 001 c1 rf6/an11 v in - v in + rf5/an10 c1out a a c1 rf6/an11 v in - v in + rf5/an10 off (read as ? 0 ? ) comparators off d d cm2:cm0 = 111 c2 rf4/an9 v in - v in + rf3/an8 off (read as ? 0 ? ) d d c1 rf6/an11 v in - v in + rf5/an10 c1out four inputs multiplexed to two comparators a a cm2:cm0 = 110 c2 rf4/an9 v in - v in + rf3/an8 c2out a a from v ref module cis = 0 cis = 1 cis = 0 cis = 1 c1 rf6/an11 v in - v in + rf5/an10 c1out two common reference comparators with outputs a a cm2:cm0 = 101 c2 rf4/an9 v in - v in + rf3/an8 c2out a d a = analog input, port reads zeros always d = digital i nput cis (cmcon<3>) is the comparator input switch cv ref c1 rf6/an11 v in - v in + rf5/an10 c1out two independent comparators with outputs a a cm2:cm0 = 011 c2 rf4/an9 v in - v in + rf3/an8 c2out a a rf2/an7/c1out rf1/an6/c2out rf2/an7/c1out rf1/an6/c2out rf2/an7/c1out
? 2004 microchip technology inc. ds39609b-page 225 pic18f6520/8520/6620/8620/6720/8720 20.2 comparator operation a single comparator is shown in figure 20-2, along with the relationship between the analog input levels and the digital output. when the analog input at v in + is less than the analog input v in -, the output of the comparator is a digital low level. when the analog input at v in + is greater than the analog input v in -, the output of the comparator is a digital high level. the shaded areas of the output of the comparator in figure 20-2 represent the uncertainty, due to input offsets and response time. 20.3 comparator reference an external or internal reference signal may be used, depending on the comparator operating mode. the analog signal present at v in - is compared to the signal at v in + and the digital output of the comparator is adjusted accordingly (figure 20-2). figure 20-2: single comparator 20.3.1 external reference signal when external voltage references are used, the comparator module can be configured to have the com- parators operate from the same, or different reference sources. however, threshold detector applications may require the same reference. the reference signal must be between v ss and v dd and can be applied to either pin of the comparator(s). 20.3.2 internal reference signal the comparator module also allows the selection of an internally generated voltage reference for the compara- tors. section 21.0 ?comparator voltage reference module? contains a detailed description of the compar- ator voltage reference module that provides this signal. the internal reference signal is used when comparators are in mode cm<2:0> = 110 (figure 20-1). in this mode, the internal voltage reference is applied to the v in + pin of both comparators. 20.4 comparator response time response time is the minimum time, after selecting a new reference voltage or input source, before the com- parator output has a valid level. if the internal reference is changed, the maximum delay of the internal voltage reference must be considered when using the compar- ator outputs. otherwise, the maximum delay of the comparators should be used ( section 26.0 ?electrical characteristics? ). 20.5 comparator outputs the comparator outputs are read through the cmcon register. these bits are read-only. the comparator outputs may also be directly output to the rf1 and rf2 i/o pins. when enabled, multiplexors in the output path of the rf1 and rf2 pins will switch and the output of each pin will be the unsynchronized output of the com- parator. the uncertainty of each of the comparators is related to the input offset voltage and the response time given in the specifications. figure 20-3 shows the comparator output block diagram. the trisf bits will still function as an output enable/ disable for the rf1 and rf2 pins while in this mode. the polarity of the comparator outputs can be changed using the c2inv and c1inv bits (cmcon<4:5>). ? + v in + v in - output v in? v in+ o utput output v in + v in - note 1: when reading the port register, all pins configured as analog inputs will read as a ? 0 ?. pins configured as digital inputs will convert an analog input, according to the schmitt trigger input specification. 2: analog levels on any pin defined as a dig- ital input may cause the input buffer to consume more current than is specified.
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 226 ? 2004 microchip technology inc. figure 20-3: comparator output block diagram 20.6 comparator interrupts the comparator interrupt flag is set whenever there is a change in the output value of either comparator. software will need to maintain information about the status of the output bits, as read from cmcon<7:6>, to determine the actual change that occurred. the cmif bit (pir registers) is the comparator interrupt flag. the cmif bit must be reset by clearing ? 0 ?. since it is also possible to write a ? 1 ? to this register, a simulated interrupt may be initiated. the cmie bit (pie registers) and the peie bit (intcon register) must be set to enable the interrupt. in addition, the gie bit must also be set. if any of these bits are clear, the interrupt is not enabled, though the cmif bit will still be set if an interrupt condition occurs. the user, in the interrupt service routine, can clear the interrupt in the following manner: a) any read or write of cmcon will end the mismatch condition. b) clear flag bit cmif. a mismatch condition will continue to set flag bit cmif. reading cmcon will end the mismatch condition and allow flag bit cmif to be cleared. d q en to rf1 or rf2 pin bus data read cmcon set multiplex cmif bit - + d q en cl port pins read cmcon reset from other comparator cxinv note: if a change in the cmcon register (c1out or c2out) should occur when a read operation is being executed (start of the q2 cycle), then the cmif (pir registers) interrupt flag may not get set.
? 2004 microchip technology inc. ds39609b-page 227 pic18f6520/8520/6620/8620/6720/8720 20.7 comparator operation during sleep when a comparator is active and the device is placed in sleep mode, the comparator remains active and the interrupt is functional, if enabled. this interrupt will wake-up the device from sleep mode, when enabled. while the comparator is powered up, higher sleep currents than shown in the power-down current specification will occur. each operational comparator will consume additional current, as shown in the com- parator specifications. to minimize power consumption while in sleep mode, turn off the comparators (cm<2:0> = 111 ) before entering sleep. if the device wakes up from sleep, the contents of the cmcon register are not affected. 20.8 effects of a reset a device reset forces the cmcon register to its reset state, causing the comparator module to be in the com- parator reset mode, cm<2:0> = 000 . this ensures that all potential inputs are analog inputs. device cur- rent is minimized when analog inputs are present at reset time. the comparators will be powered down during the reset interval. 20.9 analog input connection considerations a simplified circuit for an analog input is shown in figure 20-4. since the analog pins are connected to a digital output, they have reverse biased diodes to v dd and v ss . the analog input, therefore, must be between v ss and v dd . if the input voltage deviates from this range by more than 0.6v in either direction, one of the diodes is forward biased and a latch-up condition may occur. a maximum source impedance of 10 k ? is recommended for the analog sources. any external component connected to an analog input pin, such as a capacitor or a zener diode, should have very little leakage current. figure 20-4: comparator analog input model va r s < 10k a in c pin 5 pf v dd v t = 0.6v v t = 0.6v r ic i leakage 500 na v ss legend: c pin = input capacitance v t = threshold voltage i leakage = leakage current at the pin due to various junctions r ic = interconnect resistance r s = source impedance va = analog voltage comparator input
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 228 ? 2004 microchip technology inc. table 20-1: registers associated with comparator module name bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 value on por value on all other resets cmcon c2out c1out c2inv c1inv cis cm2 cm1 cm0 0000 0000 0000 0000 cvrcon cvren cvroe cvrr cvrss cvr3 cvr2 cvr1 cvr0 0000 0000 0000 0000 intcon gie/ gieh peie/ giel tmr0ie int0ie rbie tmr0if int0if rbif 0000 0000 0000 0000 pir2 ?cmif ? ? bclif lvdif tmr3if ccp2if -0-- 0000 -0-- 0000 pie2 ?cmie ? ? bclie lvdie tmr3ie ccp2ie -0-- 0000 -0-- 0000 ipr2 ?cmip ? ? bclip lvdip tmr3ip ccp2ip -1-- 1111 -1-- 1111 portf rf7 rf6 rf5 rf4 rf3 rf2 rf1 rf0 x000 0000 u000 0000 latf latf7 latf6 latf5 latf4 latf3 latf2 latf1 latf0 xxxx xxxx uuuu uuuu trisf trisf7 trisf6 trisf5 tris f4 trisf3 trisf2 trisf1 trisf0 1111 1111 1111 1111 legend: x = unknown, u = unchanged, ? = unimplemented, read as ? 0 ?. shaded cells are unused by the comparator module.
? 2004 microchip technology inc. ds39609b-page 229 pic18f6520/8520/6620/8620/6720/8720 21.0 comparator voltage reference module the comparator voltage reference is a 16-tap resistor ladder network that provides a selectable voltage refer- ence. the resistor ladder is segmented to provide two ranges of cv ref values and has a power-down function to conserve power when the reference is not being used. the cvrcon register controls the operation of the reference as shown in register 21-1. the block diagram is given in figure 21-1. the comparator reference supply voltage can come from either v dd or v ss , or the external v ref + and v ref - that are multiplexed with ra3 and ra2. the comparator reference supply voltage is controlled by the cvrss bit. 21.1 configuring the comparator voltage reference the comparator voltage reference can output 16 distinct voltage levels for each range. the equations used to calculate the output of the comparator voltage reference are as follows: if cvrr = 1 : cv ref = (cvr<3:0>/24) x cv rsrc if cvrr = 0 : cv ref =(cv rsrc x1/4)+(cvr<3:0>/32)xcv rsrc the settling time of the comparator voltage reference must be considered when changing the cv ref output ( section 26.0 ?electrical characteristics? ). register 21-1: cvrcon register note: in order to select external v ref + and v ref - supply voltages, the voltage reference con- figuration bits (vcfg1:vcfg0) of the adcon1 register must be set appropriately. r/w-0 r/w-0 r/w-0 r/w-0 r/w-0 r/w-0 r/w-0 r/w-0 cvren cvroe cvrr cvrss cvr3 cvr2 cvr1 cvr0 bit 7 bit 0 bit 7 cvren : comparator voltage reference enable bit 1 =cv ref circuit powered on 0 =cv ref circuit powered down bit 6 cvroe : comparator v ref output enable bit (1) 1 =cv ref voltage level is also output on the rf5/an10/cv ref pin 0 =cv ref voltage is disconnected from the rf5/an10/cv ref pin bit 5 cvrr : comparator v ref range selection bit 1 = 0.00 cv rsrc to 0.667 cv rsrc , with cv rsrc /24 step size (low range) 0 = 0.25 cv rsrc to 0.75 cv rsrc , with cv rsrc /32 step size (high range) bit 4 cvrss : comparator v ref source selection bit (2) 1 = comparator reference source cv rsrc = v ref + ? v ref - 0 = comparator reference source cv rsrc = v dd ? v ss bit 3-0 cvr3:cvr0: comparator v ref value selection bits (0 vr3:vr0 15) when cvrr = 1 : cv ref = (cvr<3:0>/24) ? (cv rsrc ) when cvrr = 0 : cv ref = 1/4 ? (cv rsrc ) + (cvr3:cvr0/32) ? (cv rsrc ) note 1: if enabled for output, rf5 must also be configured as an input by setting trisf<5> to ? 1 ?. 2: in order to select external v ref + and v ref - supply voltages, the voltage reference configuration bits (vcfg1:vcfg0) of the adcon1 register must be set appropriately. legend: r = readable bit w = writable bit u = unimplemented bit, read as ?0? - n = value at por ?1? = bit is set ?0? = bit is cleared x = bit is unknown
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 230 ? 2004 microchip technology inc. figure 21-1: voltage reference block diagram 21.2 voltage reference accuracy/error the full range of voltage reference cannot be realized due to the construction of the module. the transistors on the top and bottom of the resistor ladder network (figure 21-1) keep cv ref from approaching the refer- ence source rails. the voltage reference is derived from the reference source; therefore, the cv ref output changes with fluctuations in that source. the tested absolute accuracy of the voltage reference can be found in section 26.0 ?electrical characteristics? . 21.3 operation during sleep when the device wakes up from sleep through an interrupt or a watchdog timer time-out, the contents of the cvrcon register are not affected. to minimize current consumption in sleep mode, the voltage reference should be disabled. 21.4 effects of a reset a device reset disables the voltage reference by clearing bit cvren (cvrcon<7>). this reset also disconnects the reference from the ra2 pin by clearing bit cvroe (cvrcon<6>) and selects the high- voltage range by clearing bit cvrr (cvrcon<5>). the vrss value select bits, cvrcon<3:0>, are also cleared. 21.5 connection considerations the voltage reference module operates independently of the comparator module. the output of the reference generator may be connected to the rf5 pin if the trisf<5> bit is set and the cvroe bit is set. enabling the voltage reference output onto the rf5 pin, configured as a digital input, will increase current consumption. connecting rf5 as a digital output with vrss enabled will also increase current consumption. the rf5 pin can be used as a simple d/a output with limited drive capability. due to the limited current drive capability, a buffer must be used on the voltage refer- ence output for external connections to v ref . figure 21-2 shows an example buffering technique. note: r is defined in section 26.0 ?electrical characteristics? . cvrr 8r cvr3 cvr0 (from cvrcon<3:0>) 16-1 analog mux 8r r r r r cvren cv ref 16 stages cvrss = 0 v dd v ref + cvrss = 0 cvrss = 1 v ref - cvrss = 1
? 2004 microchip technology inc. ds39609b-page 231 pic18f6520/8520/6620/8620/6720/8720 figure 21-2: voltage reference output buffer example table 21-1: registers associated with comparator voltage reference cv ref output + ? cv ref module voltage reference output impedance r (1) rf5 note 1: r is dependent upon the comparator voltage referenc e configuration bits cvrcon<3:0> and cvrcon<5>. name bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 value on por value on all other resets cvrcon cvren cvroe cvrr cvrss cvr3 cvr2 cvr1 cvr0 0000 0000 0000 0000 cmcon c2out c1out c2inv c1inv cis cm2 cm1 cm0 0000 0000 0000 0000 trisf trisf7 trisf6 trisf5 trisf4 trisf3 trisf2 trisf1 trisf0 1111 1111 1111 1111 legend: x = unknown, u = unchanged, ? = unimplemented, read as ? 0 ?. shaded cells are not used with the comparator voltage reference.
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 232 ? 2004 microchip technology inc. notes:
? 2004 microchip technology inc. ds39609b-page 233 pic18f6520/8520/6620/8620/6720/8720 22.0 low-voltage detect in many applications, the ability to determine if the device voltage (v dd ) is below a specified voltage level is a desirable feature. a window of operation for the application can be created, where the application soft- ware can do ?housekeeping tasks? before the device voltage exits the valid operating range. this can be done using the low-voltage detect module. this module is a software programmable circuitry, where a device voltage trip point can be specified. when the voltage of the device becomes lower then the specified point, an interrupt flag is set. if the interrupt is enabled, the program execution will branch to the inter- rupt vector address and the software can then respond to that interrupt source. the low-voltage detect circuitry is completely under software control. this allows the circuitry to be ?turned off? by the software, which minimizes the current consumption for the device. figure 22-1 shows a possible application voltage curve (typically for batteries). over time, the device voltage decreases. when the device voltage equals voltage v a , the lvd logic generates an interrupt. this occurs at time t a . the application software then has the time, until the device voltage is no longer in valid operating range, to shut down the system. voltage point v b is the minimum valid operating voltage specification. this occurs at time t b . the difference t b ? t a is the total time for shutdown. figure 22-1: typical low-voltage detect application the block diagram for the lvd module is shown in figure 22-2. a comparator uses an internally gener- ated reference voltage as the set point. when the selected tap output of the device voltage crosses the set point (is lower than), the lvdif bit is set. each node in the resistor divider represents a ?trip point? voltage. the ?trip point? voltage is the minimum supply voltage level at which the device can operate before the lvd module asserts an interrupt. when the supply voltage is equal to the trip point, the voltage tapped off of the resistor array is equal to the 1.2v internal reference voltage generated by the voltage ref- erence module. the comparator then generates an interrupt signal, setting the lvdif bit. this voltage is software programmable to any one of 16 values (see figure 22-2). the trip point is selected by programming the lvdl3:lvdl0 bits (lvdcon<3:0>). time voltage v a v b t a t b v a = lvd trip point v b = minimum valid device operating voltage legend:
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 234 ? 2004 microchip technology inc. figure 22-2: low-voltage detect (lvd) block diagram the lvd module has an additional feature that allows the user to supply the trip voltage to the module from an external source. this mode is enabled when bits lvdl3:lvdl0 are set to ? 1111 ?. in this state, the com- parator input is multiplexed from the external input pin, lvdin (figure 22-3). this gives users flexibility because it allows them to configure the low-voltage detect interrupt to occur at any voltage in the valid operating range. figure 22-3: low-voltage detect (lvd) with external input block diagram lvdif v dd 16 to 1 mux lvden lvdcon internally generated reference voltage lvdin (parameter #d423) lvd3:lvd0 register lvd en 16 to 1 mux bgap boden lvden vxen lvdin v dd v dd externally generated trip point lvd3:lvd0 lvdcon register
? 2004 microchip technology inc. ds39609b-page 235 pic18f6520/8520/6620/8620/6720/8720 22.1 control register the low-voltage detect control register controls the operation of the low-voltage detect circuitry. register 22-1: lvdcon register u-0 u-0 r-0 r/w-0 r/w-0 r/w-1 r/w-0 r/w-1 ? ? irvst lvden lvdl3 lvdl2 lvdl1 lvdl0 bit 7 bit 0 bit 7-6 unimplemented: read as ? 0 ? bit 5 irvst: internal reference voltage stable flag bit 1 = indicates that the low-voltage detect logic will generate the interrupt flag at the specified voltage range 0 = indicates that the low-voltage detect logic will not generate the interrupt flag at the specified voltage range and the lvd interrupt should not be enabled bit 4 lvden: low-voltage detect power enable bit 1 = enables lvd, powers up lvd circuit 0 = disables lvd, powers down lvd circuit bit 3-0 lvdl3:lvdl0: low-voltage detection limit bits (2) 1111 = external analog input is used (input comes from the lvdin pin) 1110 = 4.64v 1101 = 4.33v 1100 = 4.13v 1011 = 3.92v 1010 = 3.72v 1001 = 3.61v 1000 = 3.41v 0111 = 3.1v 0110 = 2.89v 0101 = 2.78v 0100 = 2.58v 0011 = 2.47v 0010 = 2.27v 0001 = 2.06v 0000 = reserved note 1: lvdl3:lvdl0 modes which result in a trip point below the valid operating voltage of the device are not tested. 2: typical values shown, see parameter d420 in table 26-3 for more information. legend: r = readable bit w = writable bit u = unimplemented bit, read as ?0? - n = value at por ?1? = bit is set ?0? = bit is cleared x = bit is unknown
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 236 ? 2004 microchip technology inc. 22.2 operation depending on the power source for the device voltage, the voltage normally decreases relatively slowly. this means that the lvd module does not need to be con- stantly operating. to decrease the current require- ments, the lvd circuitry only needs to be enabled for short periods, where the voltage is checked. after doing the check, the lvd module may be disabled. each time that the lvd module is enabled, the circuitry requires some time to stabilize. after the circuitry has stabilized, all status flags may be cleared. the module will then indicate the proper state of the system. the following steps are needed to set up the lvd module: 1. write the value to the lvdl3:lvdl0 bits (lvdcon register), which selects the desired lvd trip point. 2. ensure that lvd interrupts are disabled (the lvdie bit is cleared or the gie bit is cleared). 3. enable the lvd module (set the lvden bit in the lvdcon register). 4. wait for the lvd module to stabilize (the irvst bit to become set). 5. clear the lvd interrupt flag, which may have falsely become set, until the lvd module has stabilized (clear the lvdif bit). 6. enable the lvd interrupt (set the lvdie and the gie bits). figure 22-4 shows typical waveforms that the lvd module may be used to detect. figure 22-4: low-voltage detect waveforms v lvd v dd lvdif v lvd v dd enable lvd internally generated t ivrst lvdif may not be set enable lvd lvdif lvdif cleared in software lvdif cleared in software lvdif cleared in software, case 1: case 2: lvdif remains set since lvd condition still exists reference stable internally generated reference stable t ivrst
? 2004 microchip technology inc. ds39609b-page 237 pic18f6520/8520/6620/8620/6720/8720 22.2.1 reference voltage set point the internal reference voltage of the lvd module, specified in electrical specification parameter #d423, may be used by other internal circuitry (the programmable brown-out reset). if these circuits are disabled (lower current consumption), the reference voltage circuit requires a time to become stable before a low-voltage condition can be reliably detected. this time is invariant of system clock speed. this start-up time is specified in electrical specification parameter #36. the low-voltage interrupt flag will not be enabled until a stable reference voltage is reached. refer to the waveform in figure 22-4. 22.2.2 current consumption when the module is enabled, the lvd comparator and voltage divider are enabled and will consume static cur- rent. the voltage divider can be tapped from multiple places in the resistor array. total current consumption, when enabled, is specified in electrical specification parameter #d022b. 22.3 operation during sleep when enabled, the lvd circuitry continues to operate during sleep. if the device voltage crosses the trip point, the lvdif bit will be set and the device will wake- up from sleep. device execution will continue from the interrupt vector address if interrupts have been globally enabled. 22.4 effects of a reset a device reset forces all registers to their reset state. this forces the lvd module to be turned off.
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 238 ? 2004 microchip technology inc. notes:
? 2004 microchip technology inc. ds39609b-page 239 pic18f6520/8520/6620/8620/6720/8720 23.0 special features of the cpu there are several features intended to maximize sys- tem reliability, minimize cost through elimination of external components, provide power saving operating modes and offer code protection. these are: oscillator selection reset - power-on reset (por) - power-up timer (pwrt) - oscillator start-up timer (ost) - brown-out reset (bor) interrupts watchdog timer (wdt) sleep code protection id locations in-circuit serial programming all pic18fxx20 devices have a watchdog timer, which is permanently enabled via the configuration bits, or software controlled. it runs off its own rc oscillator for added reliability. there are two timers that offer necessary delays on power-up. one is the oscillator start-up timer (ost), intended to keep the chip in reset until the crystal oscillator is stable. the other is the power-up timer (pwrt), which provides a fixed delay on power-up only, designed to keep the part in reset while the power supply stabilizes. with these two timers on-chip, most applications need no external reset circuitry. sleep mode is designed to offer a very low current power-down mode. the user can wake-up from sleep through external reset, watchdog timer wake-up or through an interrupt. several oscillator options are also made available to allow the part to fit the application. the rc oscillator option saves system cost, while the lp crystal option saves power. a set of configuration bits is used to select various options. 23.1 configuration bits the configuration bits can be programmed (read as ? 0 ?), or left unprogrammed (read as ? 1 ?), to select vari- ous device configurations. these bits are mapped, starting at program memory location 300000h. the user will note that address 300000h is beyond the user program memory space. in fact, it belongs to the configuration memory space (300000h through 3fffffh), which can only be accessed using table reads and table writes. programming the configuration registers is done in a manner similar to programming the flash memory. the eecon1 register wr bit starts a self-timed write to the configuration register. in normal operation mode, a tblwt instruction with the tblptr pointed to the configuration register sets up the address and the data for the configuration register write. setting the wr bit starts a long write to the configuration register. the configuration registers are written a byte at a time. to write or erase a configuration cell, a tblwt instruction can write a ? 1 ? or a ? 0 ? into the cell.
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 240 ? 2004 microchip technology inc. table 23-1: configuration bits and device ids register 23-1: config1h: configuration register 1 high (byte address 300001h) file name bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 default/ unprogrammed value 300001h config1h ? ?oscsen ? ? fosc2 fosc1 fosc0 --1- -111 300002h config2l ? ? ? ? borv1 borv0 boden pwrten ---- 1111 300003h config2h ? ? ? ? wdtps2 wdtps1 wdtps0 wdten ---- 1111 300004h (1) config3l wait ? ? ? ? ?pm1pm0 1--- --11 300005h config3h ? ? ? ? ? ?r (3) ccp2mx ---- --11 300006h config4l debug ? ? ? ?lvp ?stvren 1--- -1-1 300008h config5l cp7 (2) cp6 (2) cp5 (2) cp4 (2) cp3 cp2 cp1 cp0 1111 1111 300009h config5h cpd cpb ? ? ? ? ? ? 11-- ---- 30000ah config6l wrt7 (2) wrt6 (2) wrt5 (2) wrt4 (2) wrt3 wrt2 wrt1 wrt0 1111 1111 30000bh config6h wrtd wrtb wrtc ? ? ? ? ? 111- ---- 30000ch config7l ebtr7 (2) ebtr6 (2) ebtr5 (2) ebtr4 (2) ebtr3 ebtr2 ebtr1 ebtr0 1111 1111 30000dh config7h ?ebtrb ? ? ? ? ? ? -1-- ---- 3ffffeh devid1 dev2 dev1 dev0 rev4 rev3 rev2 rev1 rev0 (4) 3fffffh devid2 dev10 dev9 dev8 dev7 dev6 dev5 dev4 dev3 0000 0110 legend: x = unknown, u = unchanged, ? = unimplemented, q = value depends on condition, r = reserved. shaded cells are unimplemented, read as ? 0 ?. note 1: unimplemented in pic18f6x20 devices; maintain this bit set. 2: unimplemented in pic18fx520 and pic18fx 620 devices; maintain this bit set. 3: unimplemented in pic18fx620 and pic18fx 720 devices; maintain this bit set. 4: see register 23-13 for devid1 values. u-0 u-0 r/p-1 u-0 u-0 r/p-1 r/p-1 r/p-1 ? ? oscsen ? ? fosc2 fosc1 fosc0 bit 7 bit 0 bit 7-6 unimplemented: read as ? 0 ? bit 5 oscsen : oscillator system clock switch enable bit 1 = oscillator system clock switch option is disabled (main oscillator is source) 0 = timer1 oscillator system clock switch option is enabled (oscillator switching is enabled) bit 4-3 unimplemented: read as ? 0 ? bit 2-0 fosc2:fosc0 : oscillator selection bits 111 = rc oscillator w/ osc2 configured as ra6 110 = hs oscillator with pll enabled; clock frequency = (4 x f osc ) 101 = ec oscillator w/ osc2 configured as ra6 100 = ec oscillator w/ osc2 configured as divide-by-4 clock output 011 = rc oscillator w/ osc2 configured as divide-by-4 clock output 010 = hs oscillator 001 = xt oscillator 000 = lp oscillator legend: r = readable bit p = programmable bit u = unimplemented bit, read as ?0? - n = value when device is unprogrammed u = unchanged from programmed state
? 2004 microchip technology inc. ds39609b-page 241 pic18f6520/8520/6620/8620/6720/8720 register 23-2: config2l: configuration register 2 low (byte address 300002h) register 23-3: config2h: configuration register 2 high (byte address 300003h) u-0 u-0 u-0 u-0 r/p-1 r/p-1 r/p-1 r/p-1 ? ? ? ? borv1 borv0 boren pwrten bit 7 bit 0 bit 7-4 unimplemented: read as ? 0 ? bit 3-2 borv1:borv0: brown-out reset voltage bits 11 = v bor set to 2.5v 10 = v bor set to 2.7v 01 = v bor set to 4.2v 00 = v bor set to 4.5v bit 1 boren: brown-out reset enable bit 1 = brown-out reset enabled 0 = brown-out reset disabled bit 0 pwrten : power-up timer enable bit 1 = pwrt disabled 0 = pwrt enabled legend: r = readable bit p = programmable bit u = unimplemented bit, read as ?0? - n = value when device is unprogrammed u = unchanged from programmed state u-0 u-0 u-0 u-0 r/p-1 r/p-1 r/p-1 r/p-1 ? ? ? ? wdtps2 wdtps1 wdtps0 wdten bit 7 bit 0 bit 7-4 unimplemented: read as ? 0 ? bit 3-1 wdtps2:wdtps0: watchdog timer postscale select bits 111 = 1:128 110 = 1:64 101 = 1:32 100 = 1:16 011 = 1:8 010 = 1:4 001 = 1:2 000 = 1:1 bit 0 wdten: watchdog timer enable bit 1 = wdt enabled 0 = wdt disabled (control is placed on the swdten bit) legend: r = readable bit p = programmable bit u = unimplemented bit, read as ?0? - n = value when device is unprogrammed u = unchanged from programmed state
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 242 ? 2004 microchip technology inc. register 23-4: config3l: configuration register 3 low (byte address 300004h) (1) register 23-5: config3h: configuration register 3 high (byte address 300005h) r/p-1 u-0 u-0 u-0 u-0 u-0 r/p-1 r/p-1 wait ? ? ? ? ?pm1pm0 bit 7 bit 0 bit 7 wait: external bus data wait enable bit 1 = wait selections unavailable for table reads and table writes 0 = wait selections for table reads and table writes are determined by the wait1:wait0 bits (memcom<5:4>) bit 6-2 unimplemented: read as ? 0 ? bit 1-0 pm1:pm0: processor mode select bits 11 = microcontroller mode 10 = microprocessor mode 01 = microprocessor with boot block mode 00 = extended microcontroller mode note 1: this register is unimplemented in pic18f6x20 devices; maintain these bits set. legend: r = readable bit p = programmable bit u = unimplemented bit, read as ?0? - n = value when device is unprogrammed u = unchanged from programmed state u-0 u-0 u-0 u-0 u-0 u-0 r/p-1 r/p-1 ? ? ? ? ? ?r (1) ccp2mx bit 7 bit 0 bit 7-2 unimplemented: read as ? 0 ? bit 1 reserved: read as unknown (1) bit 0 ccp2mx: ccp2 mux bit in microcontroller mode: 1 = ccp2 input/output is multiplexed with rc1 0 = ccp2 input/output is multiplexed with re7 in microprocessor, microprocessor with boot block and extended microcontroller modes (pic18f8x20 devices only): 1 = ccp2 input/output is multiplexed with rc1 0 = ccp2 input/output is multiplexed with rb3 note 1: unimplemented in pic18fx620 and pic18fx720 devices; read as ? 0 ?. legend: r = readable bit p = programmable bit u = unimplemented bit, read as ?0? - n = value when device is unprogrammed u = unchanged from programmed state
? 2004 microchip technology inc. ds39609b-page 243 pic18f6520/8520/6620/8620/6720/8720 register 23-6: config4l: configuration register 4 low (byte address 300006h) r/p-1 u-0 u-0 u-0 u-0 r/p-1 u-0 r/p-1 debug ? ? ? ?lvp ?stvren bit 7 bit 0 bit 7 debug : background debugger enable bit 1 = background debugger disabled. rb6 and rb7 configured as general purpose i/o pins. 0 = background debugger enabled. rb6 and rb7 are dedicated to in-circuit debug. bit 6-3 unimplemented: read as ? 0 ? bit 2 lvp: low-voltage icsp enable bit 1 = low-voltage icsp enabled 0 = low-voltage icsp disabled bit 1 unimplemented: read as ? 0 ? bit 0 stvren: stack full/underflow reset enable bit 1 = stack full/underflow will cause reset 0 = stack full/underflow will not cause reset legend: r = readable bit p = programmable bit u = unimplemented bit, read as ?0? - n = value when device is unprogrammed u = unchanged from programmed state
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 244 ? 2004 microchip technology inc. register 23-7: config5l: configuration register 5 low (byte address 300008h) r/p-1 r/p-1 r/p-1 r/p-1 r/p-1 r/p-1 r/p-1 r/p-1 cp7 (1) cp6 (1) cp5 (1) cp4 (1) cp3cp2cp1cp0 bit 7 bit 0 bit 7 cp7: code protection bit (1) 1 = block 7 (01c000-01ffffh) not code-protected 0 = block 7 (01c000-01ffffh) code-protected bit 6 cp6: code protection bit (1) 1 = block 6 (018000-01bfffh) not code-protected 0 = block 6 (018000-01bfffh) code-protected bit 5 cp5: code protection bit (1) 1 = block 5 (014000-017fffh) not code-protected 0 = block 5 (014000-017fffh) code-protected bit 4 cp4: code protection bit (1) 1 = block 4 (010000-013fffh) not code-protected 0 = block 4 (010000-013fffh) code-protected bit 3 cp3: code protection bit for pic18fx520 devices: 1 = block 3 (006000-007fffh) not code-protected 0 = block 3 (006000-007fffh) code-protected for pic18fx620 and pic18fx720 devices: 1 = block 3 (00c000-00ffffh) not code-protected 0 = block 3 (00c000-00ffffh) code-protected bit 2 cp2: code protection bit for pic18fx520 devices: 1 = block 2 (004000-005fffh) not code-protected 0 = block 2 (004000-005fffh) code-protected for pic18fx620 and pic18fx720 devices: 1 = block 2 (008000-00bfffh) not code-protected 0 = block 2 (008000-00bfffh) code-protected bit 1 cp1: code protection bit for pic18fx520 devices: 1 = block 1 (002000-003fffh) not code-protected 0 = block 1 (002000-003fffh) code-protected for pic18fx620 and pic18fx720 devices: 1 = block 1 (004000-007fffh) not code-protected 0 = block 1 (004000-007fffh) code-protected bit 0 cp0: code protection bit for pic18fx520 devices: 1 = block 0 (000800-001fffh) not code-protected 0 = block 0 (000800-001fffh) code-protected for pic18fx620 and pic18fx720 devices: 1 = block 0 (000200-003fffh) not code-protected 0 = block 0 (000200-003fffh) code-protected note 1: unimplemented in pic18fx520 and pic18fx620 devices; maintain this bit set. legend: r = readable bit p = programmable bit u = unimplemented bit, read as ?0? - n = value when device is unprogrammed u = unchanged from programmed state
? 2004 microchip technology inc. ds39609b-page 245 pic18f6520/8520/6620/8620/6720/8720 register 23-8: config5h: configuration register 5 high (byte address 300009h) r/c-1 r/c-1 u-0 u-0 u-0 u-0 u-0 u-0 cpd cpb ? ? ? ? ? ? bit 7 bit 0 bit 7 cpd: data eeprom code protection bit 1 = data eeprom not code-protected 0 = data eeprom code-protected bit 6 cpb: boot block code protection bit for pic18fx520 devices: 1 = boot block (000000-0007ffh) not code-protected 0 = boot block (000000-0007ffh) code-protected for pic18fx620 and pic18fx720 devices: 1 = boot block (000000-0001ffh) not code-protected 0 = boot block (000000-0001ffh) code-protected bit 5-0 unimplemented: read as ? 0 ? legend: r = readable bit c = clearable bit u = unimplemented bit, read as ?0? - n = value when device is unprogrammed u = unchanged from programmed state
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 246 ? 2004 microchip technology inc. register 23-9: config6l: configuration register 6 low (byte address 30000ah) r/p-1 r/p-1 r/p-1 r/p-1 r/p-1 r/p-1 r/p-1 r/p-1 wrt7 (1) wrt6 (1) wrt5 (1) wrt4 (1) wrt3 wrt2 wrt1 wrt0 bit 7 bit 0 bit 7 wr7: write protection bit (1) 1 = block 7 (01c000-01ffffh) not write-protected 0 = block 7 (01c000-01ffffh) write-protected bit 6 wr6: write protection bit (1) 1 = block 6 (018000-01bfffh) not write-protected 0 = block 6 (018000-01bfffh) write-protected bit 5 wr5: write protection bit (1) 1 = block 5 (014000-017fffh) not write-protected 0 = block 5 (014000-017fffh) write-protected bit 4 wr4: write protection bit (1) 1 = block 4 (010000-013fffh) not write-protected 0 = block 4 (010000-013fffh) write-protected bit 3 wr3: write protection bit for pic18fx520 devices: 1 = block 3 (006000-007fffh) not write-protected 0 = block 3 (006000-007fffh) write-protected for pic18fx620 and pic18fx720 devices: 1 = block 3 (00c000-00ffffh) not write-protected 0 = block 3 (00c000-00ffffh) write-protected bit 2 wr2: write protection bit for pic18fx520 devices: 1 = block 2 (004000-005fffh) not write-protected 0 = block 2 (004000-005fffh) write-protected for pic18fx620 and pic18fx720 devices: 1 = block 2 (008000-00bfffh) not write-protected 0 = block 2 (008000-00bfffh) write-protected bit 1 wr1: write protection bit for pic18fx520 devices: 1 = block 1 (002000-003fffh) not write-protected 0 = block 1 (002000-003fffh) write-protected for pic18fx620 and pic18fx720 devices: 1 = block 1 (004000-007fffh) not write-protected 0 = block 1 (004000-007fffh) write-protected bit 0 wr0: write protection bit for pic18fx520 devices: 1 = block 0 (000800-001fffh) not write-protected 0 = block 0 (000800-001fffh) write-protected for pic18fx620 and pic18fx720 devices: 1 = block 0 (000200-003fffh) not write-protected 0 = block 0 (000200-003fffh) write-protected note 1: unimplemented in pic18fx520 and pic18fx620 devices; maintain this bit set. legend: r = readable bit p = programmable bit u = unimplemented bit, read as ?0? - n = value when device is unprogrammed u = unchanged from programmed state
? 2004 microchip technology inc. ds39609b-page 247 pic18f6520/8520/6620/8620/6720/8720 register 23-10: config6h: configuration register 6 high (byte address 30000bh) r/p-1 r/p-1 r-1 u-0 u-0 u-0 u-0 u-0 wrtd wrtb wrtc (1) ? ? ? ? ? bit 7 bit 0 bit 7 wrtd: data eeprom write protection bit 1 = data eeprom not write-protected 0 = data eeprom write-protected bit 6 wrtb: boot block write protection bit for pic18fx520 devices: 1 = boot block (000000-0007ffh) not write-protected 0 = boot block (000000-0007ffh) write-protected for pic18fx620 and pic18fx720 devices: 1 = boot block (000000-0001ffh) not write-protected 0 = boot block (000000-0001ffh) write-protected bit 5 wrtc: configuration register write protection bit (1) 1 = configuration registers (300000-3000ffh) not write-protected 0 = configuration registers (300000-3000ffh) write-protected note 1: this bit is read-only and cannot be changed in user mode. bit 4-0 unimplemented: read as ? 0 ? legend: r = readable bit p = programmable bit u = unimplemented bit, read as ?0? - n = value when device is unprogrammed u = unchanged from programmed state
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 248 ? 2004 microchip technology inc. register 23-11: config7l: configuration register 7 low (byte address 30000ch) r/p-1 r/p-1 r/p-1 r/p-1 r/p-1 r/p-1 r/p-1 r/p-1 ebtr7 (1) ebtr6 (1) ebtr5 (1) ebtr4 (1 ) ebtr3 ebtr2 ebtr1 ebtr0 bit 7 bit 0 bit 7 ebtr7: table read protection bit (1) 1 = block 3 (01c000-01ffffh) not protected from table reads executed in other blocks 0 = block 3 (01c000-01ffffh) protected from table reads executed in other blocks bit 6 ebtr6: table read protection bit (1) 1 = block 2 (018000-01bfffh) not protected from table reads executed in other blocks 0 = block 2 (018000-01bfffh) protected from table reads executed in other blocks bit 5 ebtr5: table read protection bit (1) 1 = block 1 (014000-017fffh) not protected from table reads executed in other blocks 0 = block 1 (014000-017fffh) protected from table reads executed in other blocks bit 4 ebtr4: table read protection bit (1) 1 = block 0 (010000-013fffh) not protected from table reads executed in other blocks 0 = block 0 (010000-013fffh) protected from table reads executed in other blocks bit 3 ebtr3: table read protection bit for pic18fx520 devices: 1 = block 3 (006000-007fffh) not protected from table reads executed in other blocks 0 = block 3 (006000-007fffh) protected from table reads executed in other blocks for pic18fx620 and pic18fx720 devices: 1 = block 3 (00c000-00ffffh) not protected from table reads executed in other blocks 0 = block 3 (00c000-00ffffh) protected from table reads executed in other blocks bit 2 ebtr2: table read protection bit for pic18fx520 devices: 1 = block 2 (004000-005fffh) not protected from table reads executed in other blocks 0 = block 2 (004000-005fffh) protected from table reads executed in other blocks for pic18fx620 and pic18fx720 devices: 1 = block 2 (008000-00bfffh) not protected from table reads executed in other blocks 0 = block 2 (008000-00bfffh) protected from table reads executed in other blocks bit 1 ebtr1: table read protection bit for pic18fx520 devices: 1 = block 1 (002000-003fffh) not protected from table reads executed in other blocks 0 = block 1 (002000-003fffh) protected from table reads executed in other blocks for pic18fx620 and pic18fx720 devices: 1 = block 1 (004000-007fffh) not protected from table reads executed in other blocks 0 = block 1 (004000-007fffh) protected from table reads executed in other blocks bit 0 ebtr0: table read protection bit for pic18fx520 devices: 1 = block 0 (000800-001fffh) not protected from table reads executed in other blocks 0 = block 0 (000800-001fffh) protected from table reads executed in other blocks for pic18fx620 and pic18fx720 devices: 1 = block 0 (000200-003fffh) not protected from table reads executed in other blocks 0 = block 0 (000200-003fffh) protected from table reads executed in other blocks note 1: unimplemented in pic18fx520 and pic18fx620 devices; maintain this bit set. legend: r = readable bit p = programmable bit u = unimplemented bit, read as ?0? - n = value when device is unprogrammed u = unchanged from programmed state
? 2004 microchip technology inc. ds39609b-page 249 pic18f6520/8520/6620/8620/6720/8720 register 23-12: config7h: configuration register 7 high (byte address 30000dh) register 23-13: device id register 1 for pic18fxx20 devices (address 3ffffeh) register 23-14: device id register 2 for pic18fxx20 devices (address 3fffffh) u-0 r/p-1 u-0 u-0 u-0 u-0 u-0 u-0 ? ebtrb ? ? ? ? ? ? bit 7 bit 0 bit 7 unimplemented: read as ? 0 ? bit 6 ebtrb: boot block table read protection bit for pic18fx520 devices: 1 = boot block (000000-0007ffh) not protected from table reads executed in other blocks 0 = boot block (000000-0007ffh) protected from table reads executed in other blocks for pic18fx620 and pic18fx720 devices: 1 = boot block (000000-0001ffh) not protected from table reads executed in other blocks 0 = boot block (000000-0001ffh) protected from table reads executed in other blocks bit 5-0 unimplemented: read as ? 0 ? legend: r = readable bit p = programmable bit u = unimplemented bit, read as ?0? - n = value when device is unprogrammed u = unchanged from programmed state rrrrrrrr dev2 dev1 dev0 rev4 rev3 rev2 rev1 rev0 bit 7 bit 0 bit 7-5 dev2:dev0: device id bits 000 = pic18f8720 001 = pic18f6720 010 = pic18f8620 011 = pic18f6620 bit 4-0 rev4:rev0: revision id bits these bits are used to indicate the device revision. legend: r = readable bit p = programmable bit u = unimplemented bit, read as ?0? - n = value when device is unprogrammed u = unchanged from programmed state rrrrrrrr dev10 dev9 dev8 dev7 dev6 dev5 dev4 dev3 bit 7 bit 0 bit 7-0 dev10:dev3: device id bits these bits are used with the dev2:dev0 bits in the device id register 1 to identify the part number. legend: r = readable bit p = programmable bit u = unimplemented bit, read as ?0? - n = value when device is unprogrammed u = unchanged from programmed state
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 250 ? 2004 microchip technology inc. 23.2 watchdog timer (wdt) the watchdog timer is a free running, on-chip rc oscillator, which does not require any external com- ponents. this rc oscillator is separate from the rc oscillator of the osc1/clki pin. that means that the wdt will run, even if the clock on the osc1/clki and osc2/clko/ra6 pins of the device has been stopped, for example, by execution of a sleep instruction. during normal operation, a wdt time-out generates a device reset (watchdog timer reset). if the device is in sleep mode, a wdt time-out causes the device to wake-up and continue with normal operation (watch- dog timer wake-up). the to bit in the rcon register will be cleared upon a wdt time-out. the watchdog timer is enabled/disabled by a device configuration bit. if the wdt is enabled, software exe- cution may not disable this function. when the wdten configuration bit is cleared, the swdten bit enables/ disables the operation of the wdt. the wdt time-out period values may be found in the electrical specifications section under parameter #31. values for the wdt postscaler may be assigned using the configuration bits. 23.2.1 control register register 23-15 shows the wdtcon register. this is a readable and writable register, which contains a control bit that allows software to override the wdt enable configuration bit, only when the configuration bit has disabled the wdt. register 23-15: wdtcon register note 1: the clrwdt and sleep instructions clear the wdt and the postscaler, if assigned to the wdt and prevent it from timing out and generating a device reset condition. 2: when a clrwdt instruction is executed and the postscaler is assigned to the wdt, the postscaler count will be cleared, but the postscaler assignment is not changed. u-0 u-0 u-0 u-0 u-0 u-0 u-0 r/w-0 ? ? ? ? ? ? ?swdten bit 7 bit 0 bit 7-1 unimplemented : read as ? 0 ? bit 0 swdten: software controlled watchdog timer enable bit 1 = watchdog timer is on 0 = watchdog timer is turned off if the wdten conf iguration bit in the configuration register = 0 legend: r = readable bit w = writable bit u = unimplemented bit, read as ?0? - n = value at por ?1? = bit is set ?0? = bit is cleared x = bit is unknown
? 2004 microchip technology inc. ds39609b-page 251 pic18f6520/8520/6620/8620/6720/8720 23.2.2 wdt postscaler the wdt has a postscaler that can extend the wdt reset period. the postscaler is selected at the time of the device programming by the value written to the config2h configuration register. figure 23-1: watchdog timer block diagram table 23-2: summary of watchdog timer registers postscaler wdt timer wdten 8-to-1 mux wdtps2:wdtps0 wdt time-out 8 swdten bit configuration bit note: wdps2:wdps0 are bits in register config2h. name bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 config2h ? ? ? ? wdtps2 wdtps2 wdtps0 wdten rcon ipen ? ? ri to pd por bor wdtcon ? ? ? ? ? ? ?swdten legend: shaded cells are not used by the watchdog timer.
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 252 ? 2004 microchip technology inc. 23.3 power-down mode (sleep) power-down mode is entered by executing a sleep instruction. if enabled, the watchdog timer will be cleared, but keeps running, the pd bit (rcon<3>) is cleared, the to (rcon<4>) bit is set and the oscillator driver is turned off. the i/o ports maintain the status they had before the sleep instruction was executed (driving high, low or high-impedance). for lowest current consumption in this mode, place all i/o pins at either v dd or v ss , ensure no external cir- cuitry is drawing current from the i/o pin, power-down the a/d and disable external clocks. pull all i/o pins that are high-impedance inputs, high or low externally, to avoid switching currents caused by floating inputs. the t0cki input should also be at v dd or v ss for low- est current consumption. the contribution from on-chip pull-ups on portb should be considered. the mclr pin must be at a logic high level (v ihmc ). 23.3.1 wake-up from sleep the device can wake-up from sleep through one of the following events: 1. external reset input on mclr pin. 2. watchdog timer wake-up (if wdt was enabled). 3. interrupt from int pin, rb port change or a peripheral interrupt. the following peripheral interrupts can wake the device from sleep: 1. psp read or write. 2. tmr1 interrupt. timer1 must be operating as an asynchronous counter. 3. tmr3 interrupt. timer3 must be operating as an asynchronous counter. 4. ccp capture mode interrupt. 5. special event trigger (timer1 in asynchronous mode using an external clock). 6. mssp (start/stop) bit detect interrupt. 7. mssp transmit or receive in slave mode (spi/i 2 c). 8. usart rx or tx (synchronous slave mode). 9. a/d conversion (when a/d clock source is rc). 10. eeprom write operation complete. 11. lvd interrupt. other peripherals cannot generate interrupts, since during sleep, no on-chip clocks are present. external mclr reset will cause a device reset. all other events are considered a continuation of program execution and will cause a ?wake-up?. the to and pd bits in the rcon register can be used to determine the cause of the device reset. the pd bit, which is set on power-up, is cleared when sleep is invoked. the to bit is cleared if a wdt time-out occurred (and caused wake-up). when the sleep instruction is being executed, the next instruction (pc + 2) is prefetched. for the device to wake-up through an interrupt event, the corresponding interrupt enable bit must be set (enabled). wake-up is regardless of the state of the gie bit. if the gie bit is clear (disabled), the device continues execution at the instruction after the sleep instruction. if the gie bit is set (enabled), the device executes the instruction after the sleep instruction and then branches to the inter- rupt address. in cases where the execution of the instruction following sleep is not desirable, the user should have a nop after the sleep instruction. 23.3.2 wake-up using interrupts when global interrupts are disabled (gie cleared) and any interrupt source has both its interrupt enable bit and interrupt flag bit set, one of the following will occur: if an interrupt condition (interrupt flag bit and interrupt enable bits are set) occurs before the execution of a sleep instruction, the sleep instruction will complete as a nop . therefore, the wdt and wdt postscaler will not be cleared, the to bit will not be set and pd bits will not be cleared. if the interrupt condition occurs during or after the execution of a sleep instruction, the device will immediately wake-up from sleep. the sleep instruction will be completely executed before the wake-up. therefore, the wdt and wdt postscaler will be cleared, the to bit will be set and the pd bit will be cleared. even if the flag bits were checked before executing a sleep instruction, it may be possible for flag bits to become set before the sleep instruction completes. to determine whether a sleep instruction executed, test the pd bit. if the pd bit is set, the sleep instruction was executed as a nop . to ensure that the wdt is cleared, a clrwdt instruction should be executed before a sleep instruction.
? 2004 microchip technology inc. ds39609b-page 253 pic18f6520/8520/6620/8620/6720/8720 figure 23-2: wake-up from sleep through interrupt (1,2) 23.4 program verification and code protection the overall structure of the code protection on the pic18 flash devices differs significantly from other picmicro ? devices. the user program memory is divided on binary boundaries into individual blocks, each of which has three separate code protection bits associated with it: code-protect bit (cpn) write-protect bit (wrtn) external block table read bit (ebtrn) the code protection bits are located in configuration registers 5l through 7h. their locations within the registers are summarized in table 23-3. in the pic18fxx20 family, the block size varies with the size of the user program memory. for pic18fx520 devices, program memory is divided into four blocks of 8 kbytes each. the first block is further divided into a boot block of 2 kbytes and a second block (block 0) of 6 kbytes, for a total of five blocks. the organization of the blocks and their associated code protection bits are shown in figure 23-3. for pic18fx620 and pic18fx720 devices, program memory is divided into blocks of 16 kbytes. the first block is further divided into a boot block of 512 bytes and a second block (block 0) of 15.5 kbytes, for a total of nine blocks. this produces five blocks for 64-kbyte devices and nine for 128-kbyte devices. the organiza- tion of the blocks and their associated code protection bits are shown in figure 23-4. table 23-3: summary of code protection registers q1 q2 q3 q4 q1 q2 q3 q4 q1 q1 q2 q3 q4 q1 q2 q3 q4 q1 q2 q3 q4 q1 q2 q3 q4 osc1 clko (4) int pin intf flag (intcon<1>) gieh bit (intcon<7>) instruction flow pc instruction fetched instruction executed pc pc+2 pc+4 inst(pc) = sleep inst(pc - 1) inst(pc + 2) sleep processor in sleep interrupt latency (3) inst(pc + 4) inst(pc + 2) inst(0008h) inst(000ah) inst(0008h) dummy cycle pc + 4 0008h 000ah dummy cycle t ost (2) pc+4 note 1: xt, hs or lp oscillator mode assumed. 2: gie = 1 assumed. in this case, after wake-up, the processor jumps to the interrupt routine. if gie = 0 , execution will continue in-line. 3: t ost = 1024 t osc (drawing not to scale). this delay will not occur for rc and ec oscillator modes. 4: clko is not available in these oscillator modes, but shown here for timing reference. file name bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 300008h config5l cp7 (1) cp6 (1) cp5 (1) cp4 (1) cp3 cp2 cp1 cp0 300009h config5h cpd cpb ? ? ? ? ? ? 30000ah config6l wrt7 (1) wrt6 (1) wrt5 (1) wrt4 (1) wrt3 wrt2 wrt1 wrt0 30000bh config6h wrtd wrtb wrtc ? ? ? ? ? 30000ch config7l ebtr7 (1) ebtr6 (1) ebtr5 (1) ebtr4 (1) ebtr3 ebtr2 ebtr1 ebtr0 30000dh config7h ? ebtrb ? ? ? ? ? ? legend: shaded cells are unimplemented. note 1: unimplemented in pic18fx520 and pic18fx620 devices.
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 254 ? 2004 microchip technology inc. figure 23-3: code-protected progra m memory for pic18fx520 devices figure 23-4: code-protected program memory for pic18fx620/x720 devices 32 kbytes address range block code protection controlled by: boot block 000000h 0007ffh cpb, wrtb, ebtrb block 0 000800h 001fffh cp0, wrt0, ebtr0 block 1 002000h 003fffh cp1, wrt1, ebtr1 block 2 004000h 005fffh cp2, wrt2, ebtr2 block 3 006000h 007fffh cp3, wrt3, ebtr3 unimplemented read ? 0 ?s 008000h 1fffffh memory size/device block code protection controlled by: 64 kbytes (pic18fx620) 128 kbytes (pic18fx720) address range boot block boot block 000000h 0001ffh cpb, wrtb, ebtrb block 0 block 0 000200h 003fffh cp0, wrt0, ebtr0 block 1 block 1 004000h 007fffh cp1, wrt1, ebtr1 block 2 block 2 008000h 00bfffh cp2, wrt2, ebtr2 block 3 block 3 00c000h 00ffffh cp3, wrt3, ebtr3 unimplemented read ? 0 ?s block 4 010000h 013fffh cp4, wrt4, ebtr4 block 5 014000h 017fffh cp5, wrt5, ebtr5 block 6 018000h 01bfffh cp6, wrt6, ebtr6 block 7 01c000h 01ffffh cp7, wrt7, ebtr7
? 2004 microchip technology inc. ds39609b-page 255 pic18f6520/8520/6620/8620/6720/8720 23.4.1 program memory code protection the user memory may be read to, or written from, any location using the table read and table write instruc- tions. the device id may be read with table reads. the configuration registers may be read and written with the table read and table write instructions. in user mode, the cpn bits have no direct effect. cpn bits inhibit external reads and writes. a block of user memory may be protected from table writes if the wrtn configuration bit is ? 0 ?. the ebtrn bits control table reads. for a block of user memory with the ebtrn bit set to ? 0 ?, a table read instruction that executes from within that block is allowed to read. a table read instruction that executes from a location out- side of that block is not allowed to read and will result in reading ? 0 ?s. figures 23-5 through 23-7 illustrate table write and table read protection using devices with a 16-kbyte block size as the models. the principles illustrated are identical for devices with an 8-kbyte block size. figure 23-5: table write (wrtn) disallowed note: code protection bits may only be written to a ? 0 ? from a ? 1 ? state. it is not possible to write a ? 1 ? to a bit in the ? 0 ? state. code pro- tection bits are only set to ? 1 ? by a full chip erase or block erase function. the full chip erase and block erase functions can only be initiated via icsp or an external programmer. 000000h 0001ffh 000200h 003fffh 004000h 007fffh 008000h 00bfffh 00c000h 00ffffh wrtb, ebtrb = 11 wrt0, ebtr0 = 01 wrt1, ebtr1 = 11 wrt2, ebtr2 = 11 wrt3, ebtr3 = 11 tblwt * tblptr = 000fffh pc = 003ffeh tblwt * pc = 008ffeh register values program memory configuration bit settings results: all table writes disabled to block n whenever wrtn = 0 .
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 256 ? 2004 microchip technology inc. figure 23-6: external block t able read (ebtrn) disallowed figure 23-7: external block table read (ebtrn) allowed wrtb, ebtrb = 11 wrt0, ebtr0 = 10 wrt1, ebtr1 = 11 wrt2, ebtr2 = 11 wrt3, ebtr3 = 11 tblrd * tblptr = 000fffh pc = 004ffeh results: all table reads from external blocks to block n are disabled whenever ebtrn = 0 . tablat register returns a value of ? 0 ?. register values program memory configuration bit settings 0001ffh 000200h 003fffh 004000h 007fffh 008000h 00bfffh 00c000h 00ffffh 000000h wrtb, ebtrb = 11 wrt0, ebtr0 = 10 wrt1, ebtr1 = 11 wrt2, ebtr2 = 11 wrt3, ebtr3 = 11 tblrd * tblptr = 000fffh pc = 003ffeh register values program memory configuration bit settings results: table reads permitted within block n, even when ebtrbn = 0 . tablat register returns the value of the data at the location tblptr. 0001ffh 000200h 003fffh 004000h 007fffh 008000h 00bfffh 00c000h 00ffffh 000000h
? 2004 microchip technology inc. ds39609b-page 257 pic18f6520/8520/6620/8620/6720/8720 23.4.2 data eeprom code protection the entire data eeprom is protected from external reads and writes by two bits: cpd and wrtd. cpd inhibits external reads and writes of data eeprom. wrtd inhibits external writes to data eeprom. the cpu can continue to read and write data eeprom, regardless of the protection bit settings. 23.4.3 configuration register protection the configuration registers can be write-protected. the wrtc bit controls protection of the configuration regis- ters. in user mode, the wrtc bit is readable only. wrtc can only be written via icsp or an external programmer. 23.5 id locations eight memory locations (200000h-200007h) are designated as id locations, where the user can store checksum or other code identification numbers. these locations are accessible during normal execution through the tblrd and tblwt instructions or during program/verify. the id locations can be read when the device is code-protected. 23.6 in-circuit serial programming pic18fx520/x620/x720 microcontrollers can be seri- ally programmed while in the end application circuit. this is simply done with two lines for clock and data and three other lines for power, ground and the programming voltage. this allows customers to manu- facture boards with unprogrammed devices and then program the microcontroller just before shipping the product. this also allows the most recent firmware or a custom firmware to be programmed. 23.7 in-circuit debugger when the debug bit in the config4l configuration register is programmed to a ? 0 ?, the in-circuit debugger functionality is enabled. this function allows simple debugging functions when used with mplab ? ide. when the microcontroller has this feature enabled, some of the resources are not available for general use. table 23-4 shows which features are consumed by the background debugger. table 23-4: debugger resources to use the in-circuit debugger function of the micro- controller, the design must implement in-circuit serial programming connections to mclr /v pp , v dd , gnd, rb7 and rb6. this will interface to the in-circuit debugger module available from microchip or one of the third party development tool companies. 23.8 low-voltage icsp programming the lvp bit in the config4l configuration register enables low-voltage icsp programming. this mode allows the microcontroller to be programmed via icsp using a v dd source in the operating voltage range. this only means that v pp does not have to be brought to v ihh , but can instead be left at the normal operating voltage. in this mode, the rb5/pgm pin is dedicated to the programming function and ceases to be a general purpose i/o pin. during programming, v dd is applied to the mclr /v pp pin. to enter programming mode, v dd must be applied to the rb5/pgm pin, provided the lvp bit is set. the lvp bit defaults to a ? 1 ? from the factory. if low-voltage programming mode is not used, the lvp bit can be programmed to a ? 0 ? and rb5/pgm becomes a digital i/o pin. however, the lvp bit may only be programmed when programming is entered with v ihh on mclr /v pp . it should be noted that once the lvp bit is programmed to ? 0 ?, only the high-voltage programming mode is available and only high-voltage programming mode can be used to program the device. when using low-voltage icsp programming, the part must be supplied 4.5v to 5.5v if a bulk erase will be executed. this includes reprogramming of the code- protect bits from an on state to an off state. for all other cases of low-voltage icsp, the part may be programmed at the normal operating voltage. this means unique user ids or user code can be reprogrammed or added. note: when performing in-circuit serial programming, verify that power is con- nected to all v dd and av dd pins of the microcontroller and that all v ss and av ss pins are grounded. i/o pins rb6, rb7 stack 2 levels program memory last 576 bytes data memory last 10 bytes note 1: the high-voltage programming mode is always available, regardless of the state of the lvp bit, by applying v ihh to the mclr pin. 2: while in low-voltage icsp mode, the rb5 pin can no longer be used as a general purpose i/o pin and should be held low during normal operation. 3: when using low-voltage icsp program- ming (lvp) and the pull-ups on portb are enabled, bit 5 in the trisb register must be cleared to disable the pull-up on rb5 and ensure the proper operation of the device.
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 258 ? 2004 microchip technology inc. notes:
? 2004 microchip technology inc. ds39609b-page 259 pic18f6520/8520/6620/8620/6720/8720 24.0 instruction set summary the pic18 instruction set adds many enhancements to the previous picmicro instruction sets, while maintain- ing an easy migration from these picmicro instruction sets. most instructions are a single program memory word (16 bits), but there are three instructions that require two program memory locations. each single-word instruction is a 16-bit word divided into an opcode, which specifies the instruction type and one or more operands, which further specify the operation of the instruction. the instruction set is highly orthogonal and is grouped into four basic categories: byte-oriented operations bit-oriented operations literal operations control operations the pic18 instruction set summary in table 24-1 lists byte-oriented , bit-oriented , literal and control operations. table 24-1 shows the opcode field descriptions. most byte-oriented instructions have three operands: 1. the file register (specified by ?f?) 2. the destination of the result (specified by ?d?) 3. the accessed memory (specified by ?a?) the file register designator ?f? specifies which file register is to be used by the instruction. the destination designator ?d? specifies where the result of the operation is to be placed. if ?d? is zero, the result is placed in the wreg register. if ?d? is one, the result is placed in the file register specified in the instruction. all bit-oriented instructions have three operands: 1. the file register (specified by ?f?) 2. the bit in the file register (specified by ?b?) 3. the accessed memory (specified by ?a?) the bit field designator ?b? selects the number of the bit affected by the operation, while the file register desig- nator ?f? represents the number of the file in which the bit is located. the literal instructions may use some of the following operands: a literal value to be loaded into a file register (specified by ?k?) the desired fsr register to load the literal value into (specified by ?f?) no operand required (specified by ???) the control instructions may use some of the following operands: a program memory address (specified by ?n?) the mode of the call or return instructions (specified by ?s?) the mode of the table read and table write instructions (specified by ?m?) no operand required (specified by ???) all instructions are a single word, except for three double-word instructions. these three instructions were made double-word instructions so that all the required information is available in these 32 bits. in the second word, the 4 msbs are ? 1 ?s. if this second word is executed as an instruction (by itself), it will execute as a nop . all single-word instructions are executed in a single instruction cycle, unless a conditional test is true or the program counter is changed as a result of the instruc- tion. in these cases, the execution takes two instruction cycles, with the additional instruction cycle(s) executed as a nop . the double-word instructions execute in two instruction cycles. one instruction cycle consists of four oscillator periods. thus, for an oscillator frequency of 4 mhz, the normal instruction execution time is 1 s. if a conditional test is true, or the program counter is changed as a result of an instruction, the instruction execution time is 2 s. two-word branch instructions (if true) would take 3 s. figure 24-1 shows the general formats that the instructions can have. all examples use the format ? nnh ? to represent a hexa- decimal number, where ? h ? signifies a hexadecimal digit. the instruction set summary, shown in table 24-1, lists the instructions recognized by the microchip assembler (mpasm tm ). section 24.1 ?instruction set? provides a description of each instruction.
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 260 ? 2004 microchip technology inc. table 24-1: opcode field descriptions field description a ram access bit a = 0 : ram location in access ram (bsr register is ignored) a = 1 : ram bank is specified by bsr register bbb bit address within an 8-bit file register (0 to 7). bsr bank select register. used to select the current ram bank. d destination select bit d = 0 : store result in wreg d = 1 : store result in file register f dest destination either the wreg register or the specified register file location. f 8-bit register file address (0x00 to 0xff). fs 12-bit register file address (0x000 to 0xfff). this is the source address. fd 12-bit register file address (0x000 to 0xfff). this is the destination address. k literal field, constant data or label (may be either an 8-bit, 12-bit or a 20-bit value). label label name. mm the mode of the tblptr register for the table read and table write instructions. only used with table read and table write instructions: * no change to register (such as tblptr with table reads and writes) *+ post-increment register (such as tblptr with table reads and writes) *- post-decrement register (such as tblptr with table reads and writes) +* pre-increment register (such as tb lptr with table reads and writes) n the relative address (2?s complement number) for relative branch instructions, or the direct address for call/ branch and return instructions. prodh product of multiply high byte. prodl product of multiply low byte. s fast call/return mode select bit s = 0 : do not update into/from shadow registers s = 1 : certain registers loaded into/from shadow registers (fast mode) u unused or unchanged. wreg working register (accumulator). x don?t care (? 0 ? or ? 1 ?). the assembler will generate code with x = 0 . it is the recommended form of use for compatibility with all microchip software tools. tblptr 21-bit table pointer (points to a program memory location). tablat 8-bit table latch. tos top-of-stack. pc program counter. pcl program counter low byte. pch program counter high byte. pclath program counter high byte latch. pclatu program counter upper byte latch. gie global interrupt enable bit. wdt watchdog timer. to time-out bit. pd power-down bit. c, dc, z, ov, n alu status bits: carry, digit carry, zero, overflow, negative. [ ] optional. ( ) contents. assigned to. < > register bit field. in the set of. italics user defined term (font is courier).
? 2004 microchip technology inc. ds39609b-page 261 pic18f6520/8520/6620/8620/6720/8720 figure 24-1: general format for instructions byte-oriented file register operations 15 10 9 8 7 0 d = 0 for result destination to be wreg register opcode d a f (file #) d = 1 for result destination to be file register (f) a = 0 to force access bank bit-oriented file register operations 15 12 11 9 8 7 0 opcode b (bit #) a f (file #) b = 3-bit position of bit in file register (f) literal operations 15 8 7 0 opcode k (literal) k = 8-bit immediate value byte to byte move operations (2-word) 15 12 11 0 opcode f (source file #) call , goto and branch operations 15 8 7 0 opcode n<7:0> (literal) n = 20-bit immediate value a = 1 for bsr to select bank f = 8-bit file register address a = 0 to force access bank a = 1 for bsr to select bank f = 8-bit file register address 15 12 11 0 1111 n<19:8> (literal) 15 12 11 0 1111 f (destination file #) f = 12-bit file register address control operations example instruction addwf myreg, w, b movff myreg1, myreg2 bsf myreg, bit, b movlw 0x7f goto label 15 8 7 0 opcode n<7:0> (literal) 15 12 11 0 n<19:8> (literal) call myfunc 15 11 10 0 opcode n<10:0> (literal) s = fast bit bra myfunc 15 8 7 0 opcode n<7:0> (literal) bc myfunc s
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 262 ? 2004 microchip technology inc. table 24-1: pic18fxxxx instruction set mnemonic, operands description cycles 16-bit instruction word status affected notes msb lsb byte-oriented file register operations addwf addwfc andwf clrf comf cpfseq cpfsgt cpfslt decf decfsz dcfsnz incf incfsz infsnz iorwf movf movff movwf mulwf negf rlcf rlncf rrcf rrncf setf subfwb subwf subwfb swapf tstfsz xorwf f, d, a f, d, a f, d, a f, a f, d, a f, a f, a f, a f, d, a f, d, a f, d, a f, d, a f, d, a f, d, a f, d, a f, d, a f s , f d f, a f, a f, a f, d, a f, d, a f, d, a f, d, a f, a f, d, a f, d, a f, d, a f, d, a f, a f, d, a add wreg and f add wreg and carry bit to f and wreg with f clear f complement f compare f with wreg, skip = compare f with wreg, skip > compare f with wreg, skip < decrement f decrement f, skip if 0 decrement f, skip if not 0 increment f increment f, skip if 0 increment f, skip if not 0 inclusive or wreg with f move f move f s (source) to 1st word f d (destination) 2nd word move wreg to f multiply wreg with f negate f rotate left f through carry rotate left f (no carry) rotate right f through carry rotate right f (no carry) set f subtract f from wreg with borrow subtract wreg from f subtract wreg from f with borrow swap nibbles in f test f, skip if 0 exclusive or wreg with f 1 1 1 1 1 1 (2 or 3) 1 (2 or 3) 1 (2 or 3) 1 1 (2 or 3) 1 (2 or 3) 1 1 (2 or 3) 1 (2 or 3) 1 1 2 1 1 1 1 1 1 1 1 1 1 1 1 1 (2 or 3) 1 0010 0010 0001 0110 0001 0110 0110 0110 0000 0010 0100 0010 0011 0100 0001 0101 1100 1111 0110 0000 0110 0011 0100 0011 0100 0110 0101 0101 0101 0011 0110 0001 01da 00da 01da 101a 11da 001a 010a 000a 01da 11da 11da 10da 11da 10da 00da 00da ffff ffff 111a 001a 110a 01da 01da 00da 00da 100a 01da 11da 10da 10da 011a 10da ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff c, dc, z, ov, n c, dc, z, ov, n z, n z z, n none none none c, dc, z, ov, n none none c, dc, z, ov, n none none z, n z, n none none none c, dc, z, ov, n c, z, n z, n c, z, n z, n none c, dc, z, ov, n c, dc, z, ov, n c, dc, z, ov, n none none z, n 1, 2 1, 2 1,2 2 1, 2 4 4 1, 2 1, 2, 3, 4 1, 2, 3, 4 1, 2 1, 2, 3, 4 4 1, 2 1, 2 1 1, 2 1, 2 1, 2 1, 2 4 1, 2 bit-oriented file register operations bcf bsf btfsc btfss btg f, b, a f, b, a f, b, a f, b, a f, d, a bit clear f bit set f bit test f, skip if clear bit test f, skip if set bit toggle f 1 1 1 (2 or 3) 1 (2 or 3) 1 1001 1000 1011 1010 0111 bbba bbba bbba bbba bbba ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff none none none none none 1, 2 1, 2 3, 4 3, 4 1, 2 note 1: when a port register is modified as a function of itself (e.g., movf portb, 1, 0 ), the value used will be that value present on the pins themselves. for example, if the data latch is ? 1 ? for a pin configured as input and is driven low by an external device, the data will be written back with a ? 0 ?. 2: if this instruction is executed on the tmr0 register (and where applicable, d = 1 ), the prescaler will be cleared if assigned. 3: if program counter (pc) is m odified or a conditional test is true, the instruction requires two cycles. the second cycle is executed as a nop . 4: some instructions are 2-word instructions. the second word of these instructions will be executed as a nop unless the first word of the instruction retrieves the information embe dded in these 16 bits. this ensur es that all program memory locations have a valid instruction. 5: if the table write starts the write cycle to internal memory, the write will continue until terminated.
? 2004 microchip technology inc. ds39609b-page 263 pic18f6520/8520/6620/8620/6720/8720 control operations bc bn bnc bnn bnov bnz bov bra bz call clrwdt daw goto nop nop pop push rcall reset retfie retlw return sleep n n n n n n n n n n, s ? ? n ? ? ? ? n s k s ? branch if carry branch if negative branch if not carry branch if not negative branch if not overflow branch if not zero branch if overflow branch unconditionally branch if zero call subroutine 1st word 2nd word clear watchdog timer decimal adjust wreg go to address 1st word 2nd word no operation no operation pop top of return stack (tos) push top of return stack (tos) relative call software device reset return from interrupt enable return with literal in wreg return from subroutine go into standby mode 1 (2) 1 (2) 1 (2) 1 (2) 1 (2) 1 (2) 1 (2) 2 1 (2) 2 1 1 2 1 1 1 1 2 1 2 2 2 1 1110 1110 1110 1110 1110 1110 1110 1101 1110 1110 1111 0000 0000 1110 1111 0000 1111 0000 0000 1101 0000 0000 0000 0000 0000 0010 0110 0011 0111 0101 0001 0100 0nnn 0000 110s kkkk 0000 0000 1111 kkkk 0000 xxxx 0000 0000 1nnn 0000 0000 1100 0000 0000 nnnn nnnn nnnn nnnn nnnn nnnn nnnn nnnn nnnn kkkk kkkk 0000 0000 kkkk kkkk 0000 xxxx 0000 0000 nnnn 1111 0001 kkkk 0001 0000 nnnn nnnn nnnn nnnn nnnn nnnn nnnn nnnn nnnn kkkk kkkk 0100 0111 kkkk kkkk 0000 xxxx 0110 0101 nnnn 1111 000s kkkk 001s 0011 none none none none none none none none none none to , pd c none none none none none none all gie/gieh, peie/giel none none to , pd 4 table 24-1: pic18fxxxx instruction set (continued) mnemonic, operands description cycles 16-bit instruction word status affected notes msb lsb note 1: when a port register is modified as a function of itself (e.g., movf portb, 1, 0 ), the value used will be that value present on the pins themselves. for example, if the data latch is ? 1 ? for a pin configured as input and is driven low by an external device, the data will be written back with a ? 0 ?. 2: if this instruction is executed on the tmr0 register (and where applicable, d = 1 ), the prescaler will be cleared if assigned. 3: if program counter (pc) is modi fied or a conditional test is true, the instruction requires two cycles. the second cycle is executed as a nop . 4: some instructions are 2-word instructions. the second word of these instructions will be executed as a nop unless the first word of the instruction retrieves the information embe dded in these 16 bits. this ensur es that all program memory locations have a valid instruction. 5: if the table write starts the write cycle to internal memory, the write will continue until terminated.
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 264 ? 2004 microchip technology inc. literal operations addlw andlw iorlw lfsr movlb movlw mullw retlw sublw xorlw k k k f, k k k k k k k add literal and wreg and literal with wreg inclusive or literal with wreg move literal (12-bit) 2nd word to fsrx 1st word move literal to bsr<3:0> move literal to wreg multiply literal with wreg return with literal in wreg subtract wreg from literal exclusive or literal with wreg 1 1 1 2 1 1 1 2 1 1 0000 0000 0000 1110 1111 0000 0000 0000 0000 0000 0000 1111 1011 1001 1110 0000 0001 1110 1101 1100 1000 1010 kkkk kkkk kkkk 00ff kkkk 0000 kkkk kkkk kkkk kkkk kkkk kkkk kkkk kkkk kkkk kkkk kkkk kkkk kkkk kkkk kkkk kkkk c, dc, z, ov, n z, n z, n none none none none none c, dc, z, ov, n z, n data memory ? program memory operations tblrd* tblrd*+ tblrd*- tblrd+* tblwt* tblwt*+ tblwt*- tblwt+* table read table read with post-increment table read with post-decrement table read with pre-increment table write table write with post-increment table write with post-decrement table write with pre-increment 2 2 (5) 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 1000 1001 1010 1011 1100 1101 1110 1111 none none none none none none none none table 24-1: pic18fxxxx instruction set (continued) mnemonic, operands description cycles 16-bit instruction word status affected notes msb lsb note 1: when a port register is modified as a function of itself (e.g., movf portb, 1, 0 ), the value used will be that value present on the pins themselves. for example, if the data latch is ? 1 ? for a pin configured as input and is driven low by an external device, the data will be written back with a ? 0 ?. 2: if this instruction is executed on the tmr0 register (and where applicable, d = 1 ), the prescaler will be cleared if assigned. 3: if program counter (pc) is m odified or a conditional test is true, the instruction requires two cycles. the second cycle is executed as a nop . 4: some instructions are 2-word instructions. the second word of these instructions will be executed as a nop unless the first word of the instruction retrieves the information embe dded in these 16 bits. this ensur es that all program memory locations have a valid instruction. 5: if the table write starts the write cycle to internal memory, the write will continue until terminated.
? 2004 microchip technology inc. ds39609b-page 265 pic18f6520/8520/6620/8620/6720/8720 24.1 instruction set addlw add literal to w syntax: [ label ] addlw k operands: 0 k 255 operation: (w) + k w status affected: n, ov, c, dc, z encoding: 0000 1111 kkkk kkkk description: the contents of w are added to the 8-bit literal ?k? and the result is placed in w. words: 1 cycles: 1 q cycle activity: q1 q2 q3 q4 decode read literal ?k? process data write to w example : addlw 0x15 before instruction w = 0x10 after instruction w = 0x25 addwf add w to f syntax: [ label ] addwf f [,d [,a] f [,d [,a] operands: 0 f 255 d [0,1] a [0,1] operation: (w) + (f) dest status affected: n, ov, c, dc, z encoding: 0010 01da ffff ffff description: add w to register ?f?. if ?d? is ? 0 ?, the result is stored in w. if ?d? is ? 1 ?, the result is stored back in register ?f? (default). if ?a? is ? 0 ?, the access bank will be selected. if ?a? is ? 1 ?, the bsr is used. words: 1 cycles: 1 q cycle activity: q1 q2 q3 q4 decode read register ?f? process data write to destination example : addwf reg, 0, 0 before instruction w = 0x17 reg = 0xc2 after instruction w=0xd9 reg = 0xc2
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 266 ? 2004 microchip technology inc. addwfc add w and carry bit to f syntax: [ label ] addwfc f [,d [,a] operands: 0 f 255 d [0,1] a [0,1] operation: (w) + (f) + (c) dest status affected: n, ov, c, dc, z encoding: 0010 00da ffff ffff description: add w, the carry flag and data memory location ?f?. if ?d? is ? 0 ?, the result is placed in w. if ?d? is ? 1 ?, the result is placed in data memory location ?f?. if ?a? is ? 0 ?, the access bank will be selected. if ?a? is ? 1 ?, the bsr will not be overridden. words: 1 cycles: 1 q cycle activity: q1 q2 q3 q4 decode read register ?f? process data write to destination example : addwfc reg, 0, 1 before instruction carry bit = 1 reg = 0x02 w = 0x4d after instruction carry bit = 0 reg = 0x02 w = 0x50 andlw and literal with w syntax: [ label ] andlw k operands: 0 k 255 operation: (w) .and. k w status affected: n, z encoding: 0000 1011 kkkk kkkk description: the contents of w are and?ed with the 8-bit literal ?k?. the result is placed in w. words: 1 cycles: 1 q cycle activity: q1 q2 q3 q4 decode read literal ?k? process data write to w example : andlw 0x5f before instruction w=0xa3 after instruction w = 0x03
? 2004 microchip technology inc. ds39609b-page 267 pic18f6520/8520/6620/8620/6720/8720 andwf and w with f syntax: [ label ] andwf f [,d [,a] operands: 0 f 255 d [0,1] a [0,1] operation: (w) .and. (f) dest status affected: n, z encoding: 0001 01da ffff ffff description: the contents of w are and?ed with register ?f?. if ?d? is ? 0 ?, the result is stored in w. if ?d? is ? 1 ?, the result is stored back in register ?f? (default). if ?a? is ? 0 ?, the access bank will be selected. if ?a? is ? 1 ?, the bsr will not be overridden (default). words: 1 cycles: 1 q cycle activity: q1 q2 q3 q4 decode read register ?f? process data write to destination example : andwf reg, 0, 0 before instruction w = 0x17 reg = 0xc2 after instruction w = 0x02 reg = 0xc2 bc branch if carry syntax: [ label ] bc n operands: -128 n 127 operation: if carry bit is ? 1 ? (pc) + 2 + 2n pc status affected: none encoding: 1110 0010 nnnn nnnn description: if the carry bit is ? 1 ?, then the program will branch. the 2?s complement number ?2n? is added to the pc. since the pc will have incremented to fetch the next instruction, the new address will be pc+2+2n. this instruction is then a two-cycle instruction. words: 1 cycles: 1(2) q cycle activity: if jump: q1 q2 q3 q4 decode read literal ?n? process data write to pc no operation no operation no operation no operation if no jump: q1 q2 q3 q4 decode read literal ?n? process data no operation example : here bc 5 before instruction pc = address (here) after instruction if carry = 1; pc = address (here+12) if carry = 0; pc = address (here+2)
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 268 ? 2004 microchip technology inc. bcf bit clear f syntax: [ label ] bcf f,b[,a] operands: 0 f 255 0 b 7 a [0,1] operation: 0 f status affected: none encoding: 1001 bbba ffff ffff description: bit ?b? in register ?f? is cleared. if ?a? is ? 0 ?, the access bank will be selected, overriding the bsr value. if ?a? = 1 , then the bank will be selected as per the bsr value (default). words: 1 cycles: 1 q cycle activity: q1 q2 q3 q4 decode read register ?f? process data write register ?f? example : bcf flag_reg, 7, 0 before instruction flag_reg = 0xc7 after instruction flag_reg = 0x47 bn branch if negative syntax: [ label ] bn n operands: -128 n 127 operation: if negative bit is ? 1 ? (pc) + 2 + 2n pc status affected: none encoding: 1110 0110 nnnn nnnn description: if the negative bit is ? 1 ?, then the program will branch. the 2?s complement number ?2n? is added to the pc. since the pc will have incremented to fetch the next instruction, the new address will be pc+2+2n. this instruction is then a two-cycle instruction. words: 1 cycles: 1(2) q cycle activity: if jump: q1 q2 q3 q4 decode read literal ?n? process data write to pc no operation no operation no operation no operation if no jump: q1 q2 q3 q4 decode read literal ?n? process data no operation example : here bn jump before instruction pc = address (here) after instruction if negative = 1; pc = address (jump) if negative = 0; pc = address (here+2)
? 2004 microchip technology inc. ds39609b-page 269 pic18f6520/8520/6620/8620/6720/8720 bnc branch if not carry syntax: [ label ] bnc n operands: -128 n 127 operation: if carry bit is ? 0 ? (pc) + 2 + 2n pc status affected: none encoding: 1110 0011 nnnn nnnn description: if the carry bit is ? 0 ?, then the program will branch. the 2?s complement number ?2n? is added to the pc. since the pc will have incremented to fetch the next instruction, the new address will be pc+2+2n. this instruction is then a two-cycle instruction. words: 1 cycles: 1(2) q cycle activity: if jump: q1 q2 q3 q4 decode read literal ?n? process data write to pc no operation no operation no operation no operation if no jump: q1 q2 q3 q4 decode read literal ?n? process data no operation example : here bnc jump before instruction pc = address (here) after instruction if carry = 0; pc = address (jump) if carry = 1; pc = address (here+2) bnn branch if not negative syntax: [ label ] bnn n operands: -128 n 127 operation: if negative bit is ? 0 ? (pc) + 2 + 2n pc status affected: none encoding: 1110 0111 nnnn nnnn description: if the negative bit is ? 0 ?, then the program will branch. the 2?s complement number ?2n? is added to the pc. since the pc will have incremented to fetch the next instruction, the new address will be pc+2+2n. this instruction is then a two-cycle instruction. words: 1 cycles: 1(2) q cycle activity: if jump: q1 q2 q3 q4 decode read literal ?n? process data write to pc no operation no operation no operation no operation if no jump: q1 q2 q3 q4 decode read literal ?n? process data no operation example : here bnn jump before instruction pc = address (here) after instruction if negative = 0; pc = address (jump) if negative = 1; pc = address (here+2)
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 270 ? 2004 microchip technology inc. bnov branch if not overflow syntax: [ label ] bnov n operands: -128 n 127 operation: if overflow bit is ? 0 ? (pc) + 2 + 2n pc status affected: none encoding: 1110 0101 nnnn nnnn description: if the overflow bit is ? 0 ?, then the program will branch. the 2?s complement number ?2n? is added to the pc. since the pc will have incremented to fetch the next instruction, the new address will be pc+2+2n. this instruction is then a two-cycle instruction. words: 1 cycles: 1(2) q cycle activity: if jump: q1 q2 q3 q4 decode read literal ?n? process data write to pc no operation no operation no operation no operation if no jump: q1 q2 q3 q4 decode read literal ?n? process data no operation example : here bnov jump before instruction pc = address (here) after instruction if overflow = 0; pc = address (jump) if overflow = 1; pc = address (here+2) bnz branch if not zero syntax: [ label ] bnz n operands: -128 n 127 operation: if zero bit is ? 0 ? (pc) + 2 + 2n pc status affected: none encoding: 1110 0001 nnnn nnnn description: if the zero bit is ? 0 ?, then the program will branch. the 2?s complement number ?2n? is added to the pc. since the pc will have incremented to fetch the next instruction, the new address will be pc+2+2n. this instruction is then a two-cycle instruction. words: 1 cycles: 1(2) q cycle activity: if jump: q1 q2 q3 q4 decode read literal ?n? process data write to pc no operation no operation no operation no operation if no jump: q1 q2 q3 q4 decode read literal ?n? process data no operation example : here bnz jump before instruction pc = address (here) after instruction if zero = 0; pc = address (jump) if zero = 1; pc = address (here+2)
? 2004 microchip technology inc. ds39609b-page 271 pic18f6520/8520/6620/8620/6720/8720 bra unconditional branch syntax: [ label ] bra n operands: -1024 n 1023 operation: (pc) + 2 + 2n pc status affected: none encoding: 1101 0nnn nnnn nnnn description: add the 2?s complement number ?2n? to the pc. since the pc will have incremented to fetch the next instruction, the new address will be pc+2+2n. this instruction is a two-cycle instruction. words: 1 cycles: 2 q cycle activity: q1 q2 q3 q4 decode read literal ?n? process data write to pc no operation no operation no operation no operation example : here bra jump before instruction pc = address (here) after instruction pc = address (jump) bsf bit set f syntax: [ label ] bsf f,b[,a] operands: 0 f 255 0 b 7 a [0,1] operation: 1 f status affected: none encoding: 1000 bbba ffff ffff description: bit ?b? in register ?f? is set. if ?a? is ? 0 ?, access bank will be selected, overriding the bsr value. if ?a? = 1 , then the bank will be selected as per the bsr value. words: 1 cycles: 1 q cycle activity: q1 q2 q3 q4 decode read register ?f? process data write register ?f? example : bsf flag_reg, 7, 1 before instruction flag_reg = 0x0a after instruction flag_reg = 0x8a
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 272 ? 2004 microchip technology inc. btfsc bit test file, skip if clear syntax: [ label ] btfsc f,b[,a] operands: 0 f 255 0 b 7 a [0,1] operation: skip if (f) = 0 status affected: none encoding: 1011 bbba ffff ffff description: if bit ?b? in register ?f? is ? 0 ?, then the next instruction is skipped. if bit ?b? is ? 0 ?, then the next instruction fetched during the current instruction execution is discarded and a nop is executed instead, making this a two-cycle instruction. if ?a? is ? 0 ?, the access bank will be selected, overriding the bsr value. if ?a? = 1 , then the bank will be selected as per the bsr value (default). words: 1 cycles: 1(2) note: 3 cycles if skip and followed by a 2-word instruction. q cycle activity: q1 q2 q3 q4 decode read register ?f? process data no operation if skip: q1 q2 q3 q4 no operation no operation no operation no operation if skip and followed by 2-word instruction: q1 q2 q3 q4 no operation no operation no operation no operation no operation no operation no operation no operation example : here false true btfsc : : flag, 1, 0 before instruction pc = address (here) after instruction if flag<1> = 0; pc = address (true) if flag<1> = 1; pc = address (false) btfss bit test file, skip if set syntax: [ label ] btfss f,b[,a] operands: 0 f 255 0 b < 7 a [0,1] operation: skip if (f) = 1 status affected: none encoding: 1010 bbba ffff ffff description: if bit ?b? in register ?f? is ? 1 ?, then the next instruction is skipped. if bit ?b? is ? 1 ?, then the next instruction fetched during the current instruction execution is discarded and a nop is executed instead, making this a two-cycle instruction. if ?a? is ? 0 ?, the access bank will be selected, overriding the bsr value. if ?a? = 1 , then the bank will be selected as per the bsr value (default). words: 1 cycles: 1(2) note: 3 cycles if skip and followed by a 2-word instruction. q cycle activity: q1 q2 q3 q4 decode read register ?f? process data no operation if skip: q1 q2 q3 q4 no operation no operation no operation no operation if skip and followed by 2-word instruction: q1 q2 q3 q4 no operation no operation no operation no operation no operation no operation no operation no operation example : here false true btfss : : flag, 1, 0 before instruction pc = address (here) after instruction if flag<1> = 0; pc = address (false) if flag<1> = 1; pc = address (true)
? 2004 microchip technology inc. ds39609b-page 273 pic18f6520/8520/6620/8620/6720/8720 btg bit toggle f syntax: [ label ] btg f,b[,a] operands: 0 f 255 0 b < 7 a [0,1] operation: (f ) f status affected: none encoding: 0111 bbba ffff ffff description: bit ?b? in data memory location ?f? is inverted. if ?a? is ? 0 ?, the access bank will be selected, overriding the bsr value. if ?a? = 1 , then the bank will be selected as per the bsr value (default). words: 1 cycles: 1 q cycle activity: q1 q2 q3 q4 decode read register ?f? process data write register ?f? example : btg portc, 4, 0 before instruction: portc = 0111 0101 [0x75] after instruction: portc = 0110 0101 [0x65] bov branch if overflow syntax: [ label ] bov n operands: -128 n 127 operation: if overflow bit is ? 1 ? (pc) + 2 + 2n pc status affected: none encoding: 1110 0100 nnnn nnnn description: if the overflow bit is ? 1 ?, then the program will branch. the 2?s complement number ?2n? is added to the pc. since the pc will have incremented to fetch the next instruction, the new address will be pc+2+2n. this instruction is then a two-cycle instruction. words: 1 cycles: 1(2) q cycle activity: if jump: q1 q2 q3 q4 decode read literal ?n? process data write to pc no operation no operation no operation no operation if no jump: q1 q2 q3 q4 decode read literal ?n? process data no operation example : here bov jump before instruction pc = address (here) after instruction if overflow = 1; pc = address (jump) if overflow = 0; pc = address (here+2)
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 274 ? 2004 microchip technology inc. bz branch if zero syntax: [ label ] bz n operands: -128 n 127 operation: if zero bit is ? 1 ? (pc) + 2 + 2n pc status affected: none encoding: 1110 0000 nnnn nnnn description: if the zero bit is ? 1 ?, then the program will branch. the 2?s complement number ?2n? is added to the pc. since the pc will have incremented to fetch the next instruction, the new address will be pc+2+2n. this instruction is then a two-cycle instruction. words: 1 cycles: 1(2) q cycle activity: if jump: q1 q2 q3 q4 decode read literal ?n? process data write to pc no operation no operation no operation no operation if no jump: q1 q2 q3 q4 decode read literal ?n? process data no operation example : here bz jump before instruction pc = address (here) after instruction if zero = 1; pc = address (jump) if zero = 0; pc = address (here+2) call subroutine call syntax: [ label ] call k [,s] operands: 0 k 1048575 s [0,1] operation: (pc) + 4 tos, k pc<20:1>, if s = 1 (w) ws, (status) statuss, (bsr) bsrs status affected: none encoding: 1st word (k<7:0>) 2nd word(k<19:8>) 1110 1111 110s k 19 kkk k 7 kkk kkkk kkkk 0 kkkk 8 description: subroutine call of entire 2-mbyte memory range. first, return address (pc+ 4) is pushed onto the return stack. if ?s? = 1 , the w, status and bsr registers are also pushed into their respective shadow registers, ws, statuss and bsrs. if ?s? = 0 , no update occurs (default). then, the 20-bit value ?k? is loaded into pc<20:1>. call is a two-cycle instruction. words: 2 cycles: 2 q cycle activity: q1 q2 q3 q4 decode read literal ?k?<7:0> push pc to stack read literal ?k?<19:8>, write to pc no operation no operation no operation no operation example : here call there,1 before instruction pc = address (here) after instruction pc = address (there) tos = address (here + 4) ws = w bsrs = bsr statuss = status
? 2004 microchip technology inc. ds39609b-page 275 pic18f6520/8520/6620/8620/6720/8720 clrf clear f syntax: [ label ] clrf f [,a] operands: 0 f 255 a [0,1] operation: 000h f 1 z status affected: z encoding: 0110 101a ffff ffff description: clears the contents of the specified register. if ?a? is ? 0 ?, the access bank will be selected, overriding the bsr value. if ?a? = 1 , then the bank will be selected as per the bsr value (default). words: 1 cycles: 1 q cycle activity: q1 q2 q3 q4 decode read register ?f? process data write register ?f? example : clrf flag_reg,1 before instruction flag_reg = 0x5a after instruction flag_reg = 0x00 clrwdt clear watchdog timer syntax: [ label ] clrwdt operands: none operation: 000h wdt, 000h wdt postscaler, 1 to, 1 pd status affected: to , pd encoding: 0000 0000 0000 0100 description: clrwdt instruction resets the watchdog timer. it also resets the postscaler of the wdt. status bits to and pd are set. words: 1 cycles: 1 q cycle activity: q1 q2 q3 q4 decode no operation process data no operation example : clrwdt before instruction wdt counter = ? after instruction wdt counter = 0x00 wdt postscaler = 0 to =1 pd =1
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 276 ? 2004 microchip technology inc. comf complement f syntax: [ label ] comf f [,d [,a] operands: 0 f 255 d [0,1] a [0,1] operation: dest status affected: n, z encoding: 0001 11da ffff ffff description: the contents of register ?f? are com- plemented. if ?d? is ? 0 ?, the result is stored in w. if ?d? is ? 1 ?, the result is stored back in register ?f? (default). if ?a? is ? 0 ?, the access bank will be selected, overriding the bsr value. if ?a? = 1 , then the bank will be selected as per the bsr value (default). words: 1 cycles: 1 q cycle activity: q1 q2 q3 q4 decode read register ?f? process data write to destination example : comf reg, 0, 0 before instruction reg = 0x13 after instruction reg = 0x13 w=0xec (f ) cpfseq compare f with w, skip if f = w syntax: [ label ] cpfseq f [,a] operands: 0 f 255 a [0,1] operation: (f) ? (w), skip if (f) = (w) (unsigned comparison) status affected: none encoding: 0110 001a ffff ffff description: compares the contents of data memory location ?f? to the contents of w by performing an unsigned subtraction. if ?f? = w , then the fetched instruction is discarded and a nop is executed instead, making this a two-cycle instruction. if ?a? is ? 0 ?, the access bank will be selected, overriding the bsr value. if ?a? = 1 , then the bank will be selected as per the bsr value (default). words: 1 cycles: 1(2) note: 3 cycles if skip and followed by a 2-word instruction. q cycle activity: q1 q2 q3 q4 decode read register ?f? process data no operation if skip: q1 q2 q3 q4 no operation no operation no operation no operation if skip and followed by 2-word instruction: q1 q2 q3 q4 no operation no operation no operation no operation no operation no operation no operation no operation example : here cpfseq reg, 0 nequal : equal : before instruction pc address = here w=? reg = ? after instruction if reg = w; pc = address (equal) if reg w; pc = address (nequal)
? 2004 microchip technology inc. ds39609b-page 277 pic18f6520/8520/6620/8620/6720/8720 cpfsgt compare f with w, skip if f > w syntax: [ label ] cpfsgt f [,a] operands: 0 f 255 a [0,1] operation: (f) ? ( w), skip if (f) > (w) (unsigned comparison) status affected: none encoding: 0110 010a ffff ffff description: compares the contents of data memory location ?f? to the contents of w by performing an unsigned subtraction. if the contents of ?f? are greater than the contents of wreg , then the fetched instruction is discarded and a nop is executed instead, making this a two-cycle instruction. if ?a? is ? 0 ?, the access bank will be selected, overriding the bsr value. if ?a? = 1 , then the bank will be selected as per the bsr value (default). words: 1 cycles: 1(2) note: 3 cycles if skip and followed by a 2-word instruction. q cycle activity: q1 q2 q3 q4 decode read register ?f? process data no operation if skip: q1 q2 q3 q4 no operation no operation no operation no operation if skip and followed by 2-word instruction: q1 q2 q3 q4 no operation no operation no operation no operation no operation no operation no operation no operation example : here cpfsgt reg, 0 ngreater : greater : before instruction pc = address (here) w= ? after instruction if reg > w; pc = address (greater) if reg w; pc = address (ngreater) cpfslt compare f with w, skip if f < w syntax: [ label ] cpfslt f [,a] operands: 0 f 255 a [0,1] operation: (f) ? ( w), skip if (f) < (w) (unsigned comparison) status affected: none encoding: 0110 000a ffff ffff description: compares the contents of data memory location ?f? to the contents of w by performing an unsigned subtraction. if the contents of ?f? are less than the contents of w, then the fetched instruction is discarded and a nop is executed instead, making this a two-cycle instruction. if ?a? is ? 0 ?, the access bank will be selected. if ?a? is ? 1 ?, the bsr will not be overridden (default). words: 1 cycles: 1(2) note: 3 cycles if skip and followed by a 2-word instruction. q cycle activity: q1 q2 q3 q4 decode read register ?f? process data no operation if skip: q1 q2 q3 q4 no operation no operation no operation no operation if skip and followed by 2-word instruction: q1 q2 q3 q4 no operation no operation no operation no operation no operation no operation no operation no operation example : here cpfslt reg, 1 nless : less : before instruction pc = address (here) w= ? after instruction if reg < w; pc = address (less) if reg w; pc = address (nless)
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 278 ? 2004 microchip technology inc. daw decimal adjust w register syntax: [ label ] daw operands: none operation: if [w<3:0> >9] or [dc = 1] then (w<3:0>) + 6 w<3:0>; else ( w<3:0>) w<3:0>; if [w<7:4> >9] or [c = 1] then ( w<7:4>) + 6 w<7:4>; else (w<7:4>) w<7:4>; status affected: c encoding: 0000 0000 0000 0111 description: daw adjusts the eight-bit value in w, resulting from the earlier addition of two variables (each in packed bcd format) and produces a correct packed bcd result. words: 1 cycles: 1 q cycle activity: q1 q2 q3 q4 decode read register w process data write w example1 : daw before instruction w=0xa5 c=0 dc = 0 after instruction w = 0x05 c=1 dc = 0 example 2 : before instruction w=0xce c=0 dc = 0 after instruction w = 0x34 c=1 dc = 0 decf decrement f syntax: [ label ] decf f [,d [,a] operands: 0 f 255 d [0,1] a [0,1] operation: (f) ? 1 dest status affected: c, dc, n, ov, z encoding: 0000 01da ffff ffff description: decrement register ?f?. if ?d? is ? 0 ?, the result is stored in w. if ?d? is ? 1 ?, the result is stored back in register ?f? (default). if ?a? is ? 0 ?, the access bank will be selected, overriding the bsr value. if ?a? = 1 , then the bank will be selected as per the bsr value (default). words: 1 cycles: 1 q cycle activity: q1 q2 q3 q4 decode read register ?f? process data write to destination example : decf cnt, 1, 0 before instruction cnt = 0x01 z=0 after instruction cnt = 0x00 z=1
? 2004 microchip technology inc. ds39609b-page 279 pic18f6520/8520/6620/8620/6720/8720 decfsz decrement f, skip if 0 syntax: [ label ] decfsz f [,d [,a]] operands: 0 f 255 d [0,1] a [0,1] operation: (f) ? 1 dest, skip if result = 0 status affected: none encoding: 0010 11da ffff ffff description: the contents of register ?f? are decremented. if ?d? is ? 0 ?, the result is placed in w. if ?d? is ? 1 ?, the result is placed back in register ?f? (default). if the result is ? 0 ?, the next instruction which is already fetched is discarded and a nop is executed instead, making it a two-cycle instruction. if ?a? is ? 0 ?, the access bank will be selected, overriding the bsr value. if ?a? = 1 , then the bank will be selected as per the bsr value (default). words: 1 cycles: 1(2) note: 3 cycles if skip and followed by a 2-word instruction. q cycle activity: q1 q2 q3 q4 decode read register ?f? process data write to destination if skip: q1 q2 q3 q4 no operation no operation no operation no operation if skip and followed by 2-word instruction: q1 q2 q3 q4 no operation no operation no operation no operation no operation no operation no operation no operation example : here decfsz cnt, 1, 1 goto loop continue before instruction pc = address (here) after instruction cnt = cnt - 1 if cnt = 0; pc = address (continue) if cnt 0; pc = address (here+2) dcfsnz decrement f, skip if not 0 syntax: [ label ] dcfsnz f [,d [,a] operands: 0 f 255 d [0,1] a [0,1] operation: (f) ? 1 dest, skip if result 0 status affected: none encoding: 0100 11da ffff ffff description: the contents of register ?f? are decremented. if ?d? is ? 0 ?, the result is placed in w. if ?d? is ? 1 ?, the result is placed back in register ?f? (default). if the result is not ? 0 ?, the next instruction which is already fetched is discarded and a nop is executed instead, making it a two-cycle instruction. if ?a? is ? 0 ?, the access bank will be selected, overriding the bsr value. if ?a? = 1 , then the bank will be selected as per the bsr value (default). words: 1 cycles: 1(2) note: 3 cycles if skip and followed by a 2-word instruction. q cycle activity: q1 q2 q3 q4 decode read register ?f? process data write to destination if skip: q1 q2 q3 q4 no operation no operation no operation no operation if skip and followed by 2-word instruction: q1 q2 q3 q4 no operation no operation no operation no operation no operation no operation no operation no operation example : here dcfsnz temp, 1, 0 zero : nzero : before instruction temp = ? after instruction temp = temp - 1, if temp = 0; pc = address (zero) if temp 0; pc = address (nzero)
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 280 ? 2004 microchip technology inc. goto unconditional branch syntax: [ label ] goto k operands: 0 k 1048575 operation: k pc<20:1> status affected: none encoding: 1st word (k<7:0>) 2nd word(k<19:8>) 1110 1111 1111 k 19 kkk k 7 kkk kkkk kkkk 0 kkkk 8 description: goto allows an unconditional branch anywhere within the entire 2-mbyte memory range. the 20-bit value ?k? is loaded into pc<20:1>. goto is always a two-cycle instruction. words: 2 cycles: 2 q cycle activity: q1 q2 q3 q4 decode read literal ?k?<7:0> no operation read literal ?k?<19:8>, write to pc no operation no operation no operation no operation example : goto there after instruction pc = address (there) incf increment f syntax: [ label ] incf f [,d [,a] operands: 0 f 255 d [0,1] a [0,1] operation: (f) + 1 dest status affected: c, dc, n, ov, z encoding: 0010 10da ffff ffff description: the contents of register ?f? are incremented. if ?d? is ? 0 ?, the result is placed in w. if ?d? is ? 1 ?, the result is placed back in register ?f? (default). if ?a? is ? 0 ?, the access bank will be selected, overriding the bsr value. if ?a? = 1 , then the bank will be selected as per the bsr value (default). words: 1 cycles: 1 q cycle activity: q1 q2 q3 q4 decode read register ?f? process data write to destination example : incf cnt, 1, 0 before instruction cnt = 0xff z=0 c=? dc = ? after instruction cnt = 0x00 z=1 c=1 dc = 1
? 2004 microchip technology inc. ds39609b-page 281 pic18f6520/8520/6620/8620/6720/8720 incfsz increment f, skip if 0 syntax: [ label ] incfsz f [,d [,a] operands: 0 f 255 d [0,1] a [0,1] operation: (f) + 1 dest, skip if result = 0 status affected: none encoding: 0011 11da ffff ffff description: the contents of register ?f? are incremented. if ?d? is ? 0 ?, the result is placed in w. if ?d? is ? 1 ?, the result is placed back in register ?f? (default). if the result is ? 0 ?, the next instruction which is already fetched is discarded and a nop is executed instead, making it a two-cycle instruction. if ?a? is ? 0 ?, the access bank will be selected, overriding the bsr value. if ?a? = 1 , then the bank will be selected as per the bsr value (default). words: 1 cycles: 1(2) note: 3 cycles if skip and followed by a 2-word instruction. q cycle activity: q1 q2 q3 q4 decode read register ?f? process data write to destination if skip: q1 q2 q3 q4 no operation no operation no operation no operation if skip and followed by 2-word instruction: q1 q2 q3 q4 no operation no operation no operation no operation no operation no operation no operation no operation example : here incfsz cnt, 1, 0 nzero : zero : before instruction pc = address (here) after instruction cnt = cnt + 1 if cnt = 0; pc = address (zero) if cnt 0; pc = address (nzero) infsnz increment f, skip if not 0 syntax: [ label ] infsnz f [,d [,a] operands: 0 f 255 d [0,1] a [0,1] operation: (f) + 1 dest, skip if result 0 status affected: none encoding: 0100 10da ffff ffff description: the contents of register ?f? are incremented. if ?d? is ? 0 ?, the result is placed in w. if ?d? is ? 1 ?, the result is placed back in register ?f? (default). if the result is not ? 0 ?, the next instruction which is already fetched is discarded and a nop is executed instead, making it a two-cycle instruction. if ?a? is ? 0 ?, the access bank will be selected, overriding the bsr value. if ?a? = 1 , then the bank will be selected as per the bsr value (default). words: 1 cycles: 1(2) note: 3 cycles if skip and followed by a 2-word instruction. q cycle activity: q1 q2 q3 q4 decode read register ?f? process data write to destination if skip: q1 q2 q3 q4 no operation no operation no operation no operation if skip and followed by 2-word instruction: q1 q2 q3 q4 no operation no operation no operation no operation no operation no operation no operation no operation example : here infsnz reg, 1, 0 zero nzero before instruction pc = address (here) after instruction reg = reg + 1 if reg 0; pc = address (nzero) if reg = 0; pc = address (zero)
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 282 ? 2004 microchip technology inc. iorlw inclusive or literal with w syntax: [ label ] iorlw k operands: 0 k 255 operation: (w) .or. k w status affected: n, z encoding: 0000 1001 kkkk kkkk description: the contents of w are or?ed with the eight-bit literal ?k?. the result is placed in w. words: 1 cycles: 1 q cycle activity: q1 q2 q3 q4 decode read literal ?k? process data write to w example : iorlw 0x35 before instruction w = 0x9a after instruction w=0xbf iorwf inclusive or w with f syntax: [ label ] iorwf f [,d [,a] operands: 0 f 255 d [0,1] a [0,1] operation: (w) .or. (f) dest status affected: n, z encoding: 0001 00da ffff ffff description: inclusive or w with register ?f?. if ?d? is ? 0 ?, the result is placed in w. if ?d? is ? 1 ?, the result is placed back in register ?f? (default). if ?a? is ? 0 ?, the access bank will be selected, over- riding the bsr value. if ?a? = 1 , then the bank will be selected as per the bsr value (default). words: 1 cycles: 1 q cycle activity: q1 q2 q3 q4 decode read register ?f? process data write to destination example : iorwf result, 0, 1 before instruction result = 0x13 w = 0x91 after instruction result = 0x13 w = 0x93
? 2004 microchip technology inc. ds39609b-page 283 pic18f6520/8520/6620/8620/6720/8720 lfsr load fsr syntax: [ label ] lfsr f,k operands: 0 f 2 0 k 4095 operation: k fsrf status affected: none encoding: 1110 1111 1110 0000 00ff k 7 kkk k 11 kkk kkkk description: the 12-bit literal ?k? is loaded into the file select register pointed to by ?f?. words: 2 cycles: 2 q cycle activity: q1 q2 q3 q4 decode read literal ?k? msb process data write literal ?k? msb to fsrfh decode read literal ?k? lsb process data write literal ?k? to fsrfl example : lfsr 2, 0x3ab after instruction fsr2h = 0x03 fsr2l = 0xab movf move f syntax: [ label ] movf f [,d [,a] operands: 0 f 255 d [0,1] a [0,1] operation: f dest status affected: n, z encoding: 0101 00da ffff ffff description: the contents of register ?f? are moved to a destination dependent upon the status of ?d?. if ?d? is ? 0 ?, the result is placed in w. if ?d? is ? 1 ?, the result is placed back in register ?f? (default). location ?f? can be anywhere in the 256-byte bank. if ?a? is ? 0 ?, the access bank will be selected, overriding the bsr value. if ?a? = 1 , then the bank will be selected as per the bsr value (default). words: 1 cycles: 1 q cycle activity: q1 q2 q3 q4 decode read register ?f? process data write w example : movf reg, 0, 0 before instruction reg = 0x22 w=0xff after instruction reg = 0x22 w = 0x22
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 284 ? 2004 microchip technology inc. movff move f to f syntax: [ label ] movff f s ,f d operands: 0 f s 4095 0 f d 4095 operation: (f s ) f d status affected: none encoding: 1st word (source) 2nd word (destin.) 1100 1111 ffff ffff ffff ffff fff f s fff f d description: the contents of source register ?f s ? are moved to destination register ?f d ?. location of source ?f s ? can be anywhere in the 4096-byte data space (000h to fffh) and location of destination ?f d ? can also be anywhere from 000h to fffh. either source or destination can be w (a useful special situation). movff is particularly useful for transferring a data memory location to a peripheral register (such as the transmit buffer or an i/o port). the movff instruction cannot use the pcl, tosu, tosh or tosl as the destination register. words: 2 cycles: 2 (3) q cycle activity: q1 q2 q3 q4 decode read register ?f? (src) process data no operation decode no operation, no dummy read no operation write register ?f? (dest) example : movff reg1, reg2 before instruction reg1 = 0x33 reg2 = 0x11 after instruction reg1 = 0x33, reg2 = 0x33 movlb move literal to low nibble in bsr syntax: [ label ] movlb k operands: 0 k 255 operation: k bsr status affected: none encoding: 0000 0001 kkkk kkkk description: the 8-bit literal ?k? is loaded into the bank select register (bsr). words: 1 cycles: 1 q cycle activity: q1 q2 q3 q4 decode read literal ?k? process data write literal ?k? to bsr example : movlb 5 before instruction bsr register = 0x02 after instruction bsr register = 0x05
? 2004 microchip technology inc. ds39609b-page 285 pic18f6520/8520/6620/8620/6720/8720 movlw move literal to w syntax: [ label ] movlw k operands: 0 k 255 operation: k w status affected: none encoding: 0000 1110 kkkk kkkk description: the eight-bit literal ?k? is loaded into w. words: 1 cycles: 1 q cycle activity: q1 q2 q3 q4 decode read literal ?k? process data write to w example : movlw 0x5a after instruction w = 0x5a movwf move w to f syntax: [ label ] movwf f [,a] operands: 0 f 255 a [0,1] operation: (w) f status affected: none encoding: 0110 111a ffff ffff description: move data from w to register ?f?. location ?f? can be anywhere in the 256-byte bank. if ?a? is ? 0 ?, the access bank will be selected, overriding the bsr value. if ?a? = 1 , then the bank will be selected as per the bsr value (default). words: 1 cycles: 1 q cycle activity: q1 q2 q3 q4 decode read register ?f? process data write register ?f? example : movwf reg, 0 before instruction w = 0x4f reg = 0xff after instruction w = 0x4f reg = 0x4f
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 286 ? 2004 microchip technology inc. mullw multiply literal with w syntax: [ label ] mullw k operands: 0 k 255 operation: (w) x k prodh:prodl status affected: none encoding: 0000 1101 kkkk kkkk description: an unsigned multiplication is carried out between the contents of w and the 8-bit literal ?k?. the 16-bit result is placed in prodh:prodl register pair. prodh contains the high byte. w is unchanged. none of the status flags are affected. note that neither overflow nor carry is possible in this operation. a zero result is possible but not detected. words: 1 cycles: 1 q cycle activity: q1 q2 q3 q4 decode read literal ?k? process data write registers prodh: prodl example : mullw 0xc4 before instruction w=0xe2 prodh = ? prodl = ? after instruction w=0xe2 prodh = 0xad prodl = 0x08 mulwf multiply w with f syntax: [ label ] mulwf f [,a] operands: 0 f 255 a [0,1] operation: (w) x (f) prodh:prodl status affected: none encoding: 0000 001a ffff ffff description an unsigned multiplication is carried out between the contents of w and the register file location ?f?. the 16-bit result is stored in the prodh:prodl register pair. prodh contains the high byte. both w and ?f? are unchanged. none of the status flags are affected. note that neither overflow nor carry is possible in this operation. a zero result is possible but not detected. if ?a? is ? 0 ?, the access bank will be selected, overriding the bsr value. if ?a?= 1 , then the bank will be selected as per the bsr value (default). words: 1 cycles: 1 q cycle activity: q1 q2 q3 q4 decode read register ?f? process data write registers prodh: prodl example : mulwf reg, 1 before instruction w=0xc4 reg = 0xb5 prodh = ? prodl = ? after instruction w=0xc4 reg = 0xb5 prodh = 0x8a prodl = 0x94
? 2004 microchip technology inc. ds39609b-page 287 pic18f6520/8520/6620/8620/6720/8720 negf negate f syntax: [ label ] negf f [,a] operands: 0 f 255 a [0,1] operation: ( f ) + 1 f status affected: n, ov, c, dc, z encoding: 0110 110a ffff ffff description: location ?f? is negated using two?s complement. the result is placed in the data memory location ?f?. if ?a? is ? 0 ?, the access bank will be selected, overriding the bsr value. if ?a? = 1 , then the bank will be selected as per the bsr value. words: 1 cycles: 1 q cycle activity: q1 q2 q3 q4 decode read register ?f? process data write register ?f? example : negf reg, 1 before instruction reg = 0011 1010 [0x3a] after instruction reg = 1100 0110 [0xc6] nop no operation syntax: [ label ] nop operands: none operation: no operation status affected: none encoding: 0000 1111 0000 xxxx 0000 xxxx 0000 xxxx description: no operation. words: 1 cycles: 1 q cycle activity: q1 q2 q3 q4 decode no operation no operation no operation example : none.
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 288 ? 2004 microchip technology inc. pop pop top of return stack syntax: [ label ] pop operands: none operation: (tos) bit bucket status affected: none encoding: 0000 0000 0000 0110 description: the tos value is pulled off the return stack and is discarded. the tos value then becomes the previous value that was pushed onto the return stack. this instruction is provided to enable the user to properly manage the return stack to incorporate a software stack. words: 1 cycles: 1 q cycle activity: q1 q2 q3 q4 decode no operation pop tos value no operation example : pop goto new before instruction tos = 0031a2h stack (1 level down) = 014332h after instruction tos = 014332h pc = new push push top of return stack syntax: [ label ] push operands: none operation: (pc+2) tos status affected: none encoding: 0000 0000 0000 0101 description: the pc+2 is pushed onto the top of the return stack. the previous tos value is pushed down on the stack. this instruction allows implementing a software stack by modifying tos and then pushing it onto the return stack. words: 1 cycles: 1 q cycle activity: q1 q2 q3 q4 decode push pc+2 onto return stack no operation no operation example : push before instruction tos = 00345ah pc = 000124h after instruction pc = 000126h tos = 000126h stack (1 level down) = 00345ah
? 2004 microchip technology inc. ds39609b-page 289 pic18f6520/8520/6620/8620/6720/8720 rcall relative call syntax: [ label ] rcall n operands: -1024 n 1023 operation: (pc) + 2 tos, (pc) + 2 + 2n pc status affected: none encoding: 1101 1nnn nnnn nnnn description: subroutine call with a jump up to 1k from the current location. first, return address (pc+2) is pushed onto the stack. then, add the 2?s complement number ?2n? to the pc. since the pc will have incremented to fetch the next instruction, the new address will be pc+2+2n. this instruction is a two-cycle instruction. words: 1 cycles: 2 q cycle activity: q1 q2 q3 q4 decode read literal ?n? push pc to stack process data write to pc no operation no operation no operation no operation example : here rcall jump before instruction pc = address (here) after instruction pc = address (jump) tos = address (here+2) reset reset syntax: [ label ] reset operands: none operation: reset all registers and flags that are affected by a mclr reset. status affected: all encoding: 0000 0000 1111 1111 description: this instruction provides a way to execute a mclr reset in software. words: 1 cycles: 1 q cycle activity: q1 q2 q3 q4 decode start reset no operation no operation example : reset after instruction registers = reset value flags* = reset value
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 290 ? 2004 microchip technology inc. retfie return from interrupt syntax: [ label ] retfie [s] operands: s [0,1] operation: (tos) pc, 1 gie/gieh or peie/giel, if s = 1 (ws) w, (statuss) status, (bsrs) bsr, pclatu, pclath are unchanged status affected: gie/gieh, peie/giel. encoding: 0000 0000 0001 000s description: return from interrupt. stack is popped and top-of-stack (tos) is loaded into the pc. interrupts are enabled by setting either the high or low priority global interrupt enable bit. if ?s? = 1 , the contents of the shadow registers, ws, statuss and bsrs, are loaded into their corresponding registers, w, status and bsr. if ?s? = 0 , no update of these registers occurs (default). words: 1 cycles: 2 q cycle activity: q1 q2 q3 q4 decode no operation no operation pop pc from stack set gieh or giel no operation no operation no operation no operation example : retfie 1 after interrupt pc = tos w=ws bsr = bsrs status = statuss gie/gieh, peie/giel = 1 retlw return literal to w syntax: [ label ] retlw k operands: 0 k 255 operation: k w, (tos) pc, pclatu, pclath are unchanged status affected: none encoding: 0000 1100 kkkk kkkk description: w is loaded with the eight-bit literal ?k?. the program counter is loaded from the top of the stack (the return address). the high address latch (pclath) remains unchanged. words: 1 cycles: 2 q cycle activity: q1 q2 q3 q4 decode read literal ?k? process data pop pc from stack, write to w no operation no operation no operation no operation example : call table ; w contains table ; offset value ; w now has ; table value : table addwf pcl ; w = offset retlw k0 ; begin table retlw k1 ; : : retlw kn ; end of table before instruction w = 0x07 after instruction w = value of kn
? 2004 microchip technology inc. ds39609b-page 291 pic18f6520/8520/6620/8620/6720/8720 return return from subroutine syntax: [ label ] return [s] operands: s [0,1] operation: (tos) pc, if s = 1 (ws) w, (statuss) status, (bsrs) bsr, pclatu, pclath are unchanged status affected: none encoding: 0000 0000 0001 001s description: return from subroutine. the stack is popped and the top of the stack (tos) is loaded into the program counter. if ?s? = 1 , the contents of the shadow registers, ws, statuss and bsrs, are loaded into their corresponding registers, w, status and bsr. if ?s? = 0 , no update of these registers occurs (default). words: 1 cycles: 2 q cycle activity: q1 q2 q3 q4 decode no operation process data pop pc from stack no operation no operation no operation no operation example : return after interrupt pc = tos rlcf rotate left f through carry syntax: [ label ] rlcf f [,d [,a] operands: 0 f 255 d [0,1] a [0,1] operation: (f) dest, (f<7>) c, (c) dest<0> status affected: c, n, z encoding: 0011 01da ffff ffff description: the contents of register ?f? are rotated one bit to the left through the carry flag. if ?d? is ? 0 ?, the result is placed in w. if ?d? is ? 1 ?, the result is stored back in register ?f? (default). if ?a? is ? 0 ?, the access bank will be selected, overriding the bsr value. if ?a? = 1 , then the bank will be selected as per the bsr value (default). words: 1 cycles: 1 q cycle activity: q1 q2 q3 q4 decode read register ?f? process data write to destination example : rlcf reg, 0, 0 before instruction reg = 1110 0110 c= 0 after instruction reg = 1110 0110 w= 1100 1100 c= 1 c register f
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 292 ? 2004 microchip technology inc. rlncf rotate left f (no carry) syntax: [ label ] rlncf f [,d [,a] operands: 0 f 255 d [0,1] a [0,1] operation: (f) dest, (f<7>) dest<0> status affected: n, z encoding: 0100 01da ffff ffff description: the contents of register ?f? are rotated one bit to the left. if ?d? is ? 0 ?, the result is placed in w. if ?d? is ? 1 ?, the result is stored back in register ?f? (default). if ?a? is ? 0 ?, the access bank will be selected, overriding the bsr value. if ?a? is ? 1 ?, then the bank will be selected as per the bsr value (default). words: 1 cycles: 1 q cycle activity: q1 q2 q3 q4 decode read register ?f? process data write to destination example : rlncf reg, 1, 0 before instruction reg = 1010 1011 after instruction reg = 0101 0111 register f rrcf rotate right f through carry syntax: [ label ] rrcf f [,d [,a] operands: 0 f 255 d [0,1] a [0,1] operation: (f) dest, (f<0>) c, (c) dest<7> status affected: c, n, z encoding: 0011 00da ffff ffff description: the contents of register ?f? are rotated one bit to the right through the carry flag. if ?d? is ? 0 ?, the result is placed in w. if ?d? is ? 1 ?, the result is placed back in register ?f? (default). if ?a? is ? 0 ?, the access bank will be selected, overriding the bsr value. if ?a? is ? 1 ?, then the bank will be selected as per the bsr value (default). words: 1 cycles: 1 q cycle activity: q1 q2 q3 q4 decode read register ?f? process data write to destination example : rrcf reg, 0, 0 before instruction reg = 1110 0110 c= 0 after instruction reg = 1110 0110 w= 0111 0011 c= 0 c register f
? 2004 microchip technology inc. ds39609b-page 293 pic18f6520/8520/6620/8620/6720/8720 rrncf rotate right f (no carry) syntax: [ label ] rrncf f [,d [,a] operands: 0 f 255 d [0,1] a [0,1] operation: (f) dest, (f<0>) dest<7> status affected: n, z encoding: 0100 00da ffff ffff description: the contents of register ?f? are rotated one bit to the right. if ?d? is ? 0 ?, the result is placed in w. if ?d? is ? 1 ?, the result is placed back in register ?f? (default). if ?a? is ? 0 ?, the access bank will be selected, overriding the bsr value. if ?a? is ? 1 ?, then the bank will be selected as per the bsr value (default). words: 1 cycles: 1 q cycle activity: q1 q2 q3 q4 decode read register ?f? process data write to destination example 1 : rrncf reg, 1, 0 before instruction reg = 1101 0111 after instruction reg = 1110 1011 example 2 : rrncf reg, 0, 0 before instruction w=? reg = 1101 0111 after instruction w= 1110 1011 reg = 1101 0111 register f setf set f syntax: [ label ] setf f [,a] operands: 0 f 255 a [0,1] operation: ffh f status affected: none encoding: 0110 100a ffff ffff description: the contents of the specified register are set to ffh. if ?a? is ? 0 ?, the access bank will be selected, overriding the bsr value. if ?a? is ? 1 ?, then the bank will be selected as per the bsr value (default). words: 1 cycles: 1 q cycle activity: q1 q2 q3 q4 decode read register ?f? process data write register ?f? example : setf reg,1 before instruction reg = 0x5a after instruction reg = 0xff
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 294 ? 2004 microchip technology inc. sleep enter sleep mode syntax: [ label ] sleep operands: none operation: 00h wdt, 0 wdt postscaler, 1 to , 0 pd status affected: to , pd encoding: 0000 0000 0000 0011 description: the power-down status bit (pd ) is cleared. the time-out status bit (to ) is set. watchdog timer and its postscaler are cleared. the processor is put into sleep mode with the oscillator stopped. words: 1 cycles: 1 q cycle activity: q1 q2 q3 q4 decode no operation process data go to sleep example : sleep before instruction to =? pd =? after instruction to =1 ? pd =0 ? if wdt causes wake-up, this bit is cleared. subfwb subtract f from w with borrow syntax: [ label ] subfwb f [,d [,a] operands: 0 f 255 d [0,1] a [0,1] operation: (w) ? (f) ? (c ) dest status affected: n, ov, c, dc, z encoding: 0101 01da ffff ffff description: subtract register ?f? and carry flag (borrow) from w (2?s complement method). if ?d? is ? 0 ?, the result is stored in w. if ?d? is ? 1 ?, the result is stored in register ?f? (default). if ?a? is ? 0 ?, the access bank will be selected, overriding the bsr value. if ?a? is ? 1 ?, then the bank will be selected as per the bsr value (default). words: 1 cycles: 1 q cycle activity: q1 q2 q3 q4 decode read register ?f? process data write to destination example 1 : subfwb reg, 1, 0 before instruction reg = 3 w=2 c=1 after instruction reg = ff w=2 c=0 z=0 n = 1 ; result is negative example 2 : subfwb reg, 0, 0 before instruction reg = 2 w=5 c=1 after instruction reg = 2 w=3 c=1 z=0 n = 0 ; result is positive example 3 : subfwb reg, 1, 0 before instruction reg = 1 w=2 c=0 after instruction reg = 0 w=2 c=1 z = 1 ; result is zero n=0
? 2004 microchip technology inc. ds39609b-page 295 pic18f6520/8520/6620/8620/6720/8720 sublw subtract w from literal syntax: [ label ]sublw k operands: 0 k 255 operation: k ? (w) w status affected: n, ov, c, dc, z encoding: 0000 1000 kkkk kkkk description: w is subtracted from the eight-bit literal ?k?. the result is placed in w. words: 1 cycles: 1 q cycle activity: q1 q2 q3 q4 decode read literal ?k? process data write to w example 1: sublw 0x02 before instruction w=1 c=? after instruction w=1 c = 1 ; result is positive z=0 n=0 example 2 : sublw 0x02 before instruction w=2 c=? after instruction w=0 c = 1 ; result is zero z=1 n=0 example 3 : sublw 0x02 before instruction w=3 c=? after instruction w = ff ; (2?s complement) c = 0 ; result is negative z=0 n=1 subwf subtract w from f syntax: [ label ] subwf f [,d [,a] operands: 0 f 255 d [0,1] a [0,1] operation: (f) ? (w) dest status affected: n, ov, c, dc, z encoding: 0101 11da ffff ffff description: subtract w from register ?f? (2?s complement method). if ?d? is ? 0 ?, the result is stored in w. if ?d? is ? 1 ?, the result is stored back in register ?f? (default). if ?a? is ? 0 ?, the access bank will be selected, overriding the bsr value. if ?a? is ? 1 ?, then the bank will be selected as per the bsr value (default). words: 1 cycles: 1 q cycle activity: q1 q2 q3 q4 decode read register ?f? process data write to destination example 1 : subwf reg, 1, 0 before instruction reg = 3 w=2 c=? after instruction reg = 1 w=2 c = 1 ; result is positive z=0 n=0 example 2 : subwf reg, 0, 0 before instruction reg = 2 w=2 c=? after instruction reg = 2 w=0 c=1; result is zero z=1 n=0 example 3 : subwf reg, 1, 0 before instruction reg = 1 w=2 c=? after instruction reg = ffh ;(2?s complement) w=2 c = 0 ; result is negative z=0 n=1
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 296 ? 2004 microchip technology inc. subwfb subtract w from f with borrow syntax: [ label ] subwfb f [,d [,a] operands: 0 f 255 d [0,1] a [0,1] operation: (f) ? (w) ? (c ) dest status affected: n, ov, c, dc, z encoding: 0101 10da ffff ffff description: subtract w and the carry flag (borrow) from register ?f? (2?s com- plement method). if ?d? is ? 0 ?, the result is stored in w. if ?d? is ? 1 ?, the result is stored back in register ?f? (default). if ?a? is ? 0 ?, the access bank will be selected, overriding the bsr value. if ?a? is ? 1 ?, then the bank will be selected as per the bsr value (default). words: 1 cycles: 1 q cycle activity: q1 q2 q3 q4 decode read register ?f? process data write to destination example 1 : subwfb reg, 1, 0 before instruction reg = 0x19 (0001 1001) w = 0x0d (0000 1101) c=1 after instruction reg = 0x0c (0000 1011) w = 0x0d (0000 1101) c=1 z=0 n = 0 ; result is positive example 2 : subwfb reg, 0, 0 before instruction reg = 0x1b (0001 1011) w = 0x1a (0001 1010) c=0 after instruction reg = 0x1b (0001 1011) w = 0x00 c=1 z = 1 ; result is zero n=0 example 3: subwfb reg, 1, 0 before instruction reg = 0x03 (0000 0011) w = 0x0e (0000 1101) c=1 after instruction reg = 0xf5 (1111 0100) ; [2?s comp] w = 0x0e (0000 1101) c=0 z=0 n = 1 ; result is negative swapf swap f syntax: [ label ] swapf f [,d [,a] operands: 0 f 255 d [0,1] a [0,1] operation: (f<3:0>) dest<7:4>, (f<7:4>) dest<3:0> status affected: none encoding: 0011 10da ffff ffff description: the upper and lower nibbles of register ?f? are exchanged. if ?d? is ? 0 ?, the result is placed in w. if ?d? is ? 1 ?, the result is placed in register ?f? (default). if ?a? is ? 0 ?, the access bank will be selected, overriding the bsr value. if ?a? is ? 1 ?, then the bank will be selected as per the bsr value (default). words: 1 cycles: 1 q cycle activity: q1 q2 q3 q4 decode read register ?f? process data write to destination example : swapf reg, 1, 0 before instruction reg = 0x53 after instruction reg = 0x35
? 2004 microchip technology inc. ds39609b-page 297 pic18f6520/8520/6620/8620/6720/8720 tblrd table read syntax: [ label ] tblrd ( *; *+; *-; +*) operands: none operation: if tblrd *, (prog mem (tblptr)) tablat; tblptr ? no change; if tblrd *+, (prog mem (tblptr)) tablat; (tblptr) + 1 tblptr; if tblrd *-, (prog mem (tblptr)) tablat; (tblptr) ? 1 tblptr; if tblrd +*, (tblptr) + 1 tblptr; (prog mem (tblptr)) tablat; status affected:none encoding: 0000 0000 0000 10nn nn=0 * =1 *+ =2 *- =3 +* description: this instruction is used to read the contents of program memory (p.m.). to address the program memory, a pointer called table pointer (tblptr) is used. the tblptr (a 21-bit pointer) points to each byte in the program memory. tblptr has a 2-mbyte address range. tblptr[0] = 0 : least significant byte of program memory word tblptr[0] = 1 : most significant byte of program memory word the tblrd instruction can modify the value of tblptr as follows: no change post-increment post-decrement pre-increment words: 1 cycles: 2 q cycle activity: q1 q2 q3 q4 decode no operation no operation no operation no operation no operation (read program memory) no operation no operation (write tablat) tblrd table read (continued) example 1 : tblrd *+ ; before instruction tablat = 0x55 tblptr = 0x00a356 memory(0x00a356) = 0x34 after instruction tablat = 0x34 tblptr = 0x00a357 example 2 : tblrd +* ; before instruction tablat = 0xaa tblptr = 0x01a357 memory(0x01a357) = 0x12 memory(0x01a358) = 0x34 after instruction tablat = 0x34 tblptr = 0x01a358
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 298 ? 2004 microchip technology inc. tblwt table write syntax: [ label ] tblwt ( *; *+; *-; +*) operands: none operation: if tblwt*, (tablat) holding register; tblptr ? no change; if tblwt*+, (tablat) holding register; (tblptr) + 1 tblptr; if tblwt*-, (tablat) holding register; (tblptr) ? 1 tblptr; if tblwt+*, (tblptr) + 1 tblptr; (tablat) holding register; status affected: none encoding: 0000 0000 0000 11nn nn=0 * =1 *+ =2 *- =3 +* description: this instruction uses the 3 lsbs of tblptr to determine which of the 8 holding registers the tablat is written to. the holding registers are used to program the contents of program memory (p.m.). (refer to section 5.0 ?flash program memory? for additional details on programming flash memory.) the tblptr (a 21-bit pointer) points to each byte in the program memory. tblptr has a 2-mbyte address range. the lsb of the tblptr selects which byte of the program memory location to access. tblptr[0] = 0 : least significant byte of program memory word tblptr[0] = 1 : most significant byte of program memory word the tblwt instruction can modify the value of tblptr as follows: no change post-increment post-decrement pre-increment tblwt table write (continued) words: 1 cycles: 2 q cycle activity: q1 q2 q3 q4 decode no operation no operation no operation no operation no operation (read tablat) no operation no operation (write to holding register ) example 1 : tblwt *+; before instruction tablat = 0x55 tblptr = 0x00a356 holding register (0x00a356) = 0xff after instructions (table write completion) tablat = 0x55 tblptr = 0x00a357 holding register (0x00a356) = 0x55 example 2 : tblwt +*; before instruction tablat = 0x34 tblptr = 0x01389a holding register (0x01389a) = 0xff holding register (0x01389b) = 0xff after instruction (table write completion) tablat = 0x34 tblptr = 0x01389b holding register (0x01389a) = 0xff holding register (0x01389b) = 0x34
? 2004 microchip technology inc. ds39609b-page 299 pic18f6520/8520/6620/8620/6720/8720 tstfsz test f, skip if 0 syntax: [ label ] tstfsz f [,a] operands: 0 f 255 a [0,1] operation: skip if f = 0 status affected: none encoding: 0110 011a ffff ffff description: if ?f? = 0 , the next instruction, fetched during the current instruction execution is discarded and a nop is executed, making this a two-cycle instruction. if ?a? is ? 0 ?, the access bank will be selected, overriding the bsr value. if ?a? is ? 1 ?, then the bank will be selected as per the bsr value (default). words: 1 cycles: 1(2) note: 3 cycles if skip and followed by a 2-word instruction. q cycle activity: q1 q2 q3 q4 decode read register ?f? process data no operation if skip: q1 q2 q3 q4 no operation no operation no operation no operation if skip and followed by 2-word instruction: q1 q2 q3 q4 no operation no operation no operation no operation no operation no operation no operation no operation example : here tstfsz cnt, 1 nzero : zero : before instruction pc = address (here) after instruction if cnt = 0x00, pc = address (zero) if cnt 0x00, pc = address (nzero) xorlw exclusive or literal with w syntax: [ label ] xorlw k operands: 0 k 255 operation: (w) .xor. k w status affected: n, z encoding: 0000 1010 kkkk kkkk description: the contents of w are xor?ed with the 8-bit literal ?k?. the result is placed in w. words: 1 cycles: 1 q cycle activity: q1 q2 q3 q4 decode read literal ?k? process data write to w example : xorlw 0xaf before instruction w=0xb5 after instruction w = 0x1a
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 300 ? 2004 microchip technology inc. xorwf exclusive or w with f syntax: [ label ] xorwf f [,d [,a] operands: 0 f 255 d [0,1] a [0,1] operation: (w) .xor. (f) dest status affected: n, z encoding: 0001 10da ffff ffff description: exclusive or the contents of w with register ?f?. if ?d? is ? 0 ?, the result is stored in w. if ?d? is ? 1 ?, the result is stored back in register ?f? (default). if ?a? is ? 0 ?, the access bank will be selected, overriding the bsr value. if ?a? is ? 1 ?, then the bank will be selected as per the bsr value (default). words: 1 cycles: 1 q cycle activity: q1 q2 q3 q4 decode read register ?f? process data write to destination example : xorwf reg, 1, 0 before instruction reg = 0xaf w=0xb5 after instruction reg = 0x1a w=0xb5
? 2004 microchip technology inc. ds39609b-page 301 pic18f6520/8520/6620/8620/6720/8720 25.0 development support the picmicro ? microcontrollers are supported with a full range of hardware and software development tools: integrated development environment - mplab ? ide software assemblers/compilers/linkers - mpasm tm assembler - mplab c17 and mplab c18 c compilers -mplink tm object linker/ mplib tm object librarian - mplab c30 c compiler - mplab asm30 assembler/linker/library simulators - mplab sim software simulator - mplab dspic30 software simulator emulators - mplab ice 2000 in-circuit emulator - mplab ice 4000 in-circuit emulator in-circuit debugger - mplab icd 2 device programmers -pro mate ? ii universal device programmer - picstart ? plus development programmer - mplab pm3 device programmer low-cost demonstration boards - picdem tm 1 demonstration board - picdem.net tm demonstration board - picdem 2 plus demonstration board - picdem 3 demonstration board - picdem 4 demonstration board - picdem 17 demonstration board - picdem 18r demonstration board - picdem lin demonstration board - picdem usb demonstration board evaluation kits -k ee l oq ? - picdem msc -microid ? -can - powersmart ? -analog 25.1 mplab integrated development environment software the mplab ide software brings an ease of software development previously unseen in the 8/16-bit micro- controller market. the mplab ide is a windows ? based application that contains: an interface to debugging tools - simulator - programmer (sold separately) - emulator (sold separately) - in-circuit debugger (sold separately) a full-featured editor with color coded context a multiple project manager customizable data windows with direct edit of contents high-level source code debugging mouse over variable inspection extensive on-line help the mplab ide allows you to: edit your source files (either assembly or c) one touch assemble (or compile) and download to picmicro emulator and simulator tools (automatically updates all project information) debug using: - source files (assembly or c) - mixed assembly and c - machine code mplab ide supports multiple debugging tools in a single development paradigm, from the cost effective simulators, through low-cost in-circuit debuggers, to full-featured emulators. this eliminates the learning curve when upgrading to tools with increasing flexibility and power. 25.2 mpasm assembler the mpasm assembler is a full-featured, universal macro assembler for all picmicro mcus. the mpasm assembler generates relocatable object files for the mplink object linker, intel ? standard hex files, map files to detail memory usage and symbol ref- erence, absolute lst files that contain source lines and generated machine code and coff files for debugging. the mpasm assembler features include: integration into mplab ide projects user defined macros to streamline assembly code conditional assembly for multi-purpose source files directives that allow complete control over the assembly process
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 302 ? 2004 microchip technology inc. 25.3 mplab c17 and mplab c18 c compilers the mplab c17 and mplab c18 code development systems are complete ansi c compilers for microchip?s pic17cxxx and pic18cxxx family of microcontrollers. these compilers provide powerful integration capabilities, superior code optimization and ease of use not found with other compilers. for easy source level debugging, the compilers provide symbol information that is optimized to the mplab ide debugger. 25.4 mplink object linker/ mplib object librarian the mplink object linker combines relocatable objects created by the mpasm assembler and the mplab c17 and mplab c18 c compilers. it can link relocatable objects from precompiled libraries, using directives from a linker script. the mplib object librarian manages the creation and modification of library files of precompiled code. when a routine from a library is called from a source file, only the modules that contain that routine will be linked in with the application. this allows large libraries to be used efficiently in many different applications. the object linker/library features include: efficient linking of single libraries instead of many smaller files enhanced code maintainability by grouping related modules together flexible creation of libraries with easy module listing, replacement, deletion and extraction 25.5 mplab c30 c compiler the mplab c30 c compiler is a full-featured, ansi compliant, optimizing compiler that translates standard ansi c programs into dspic30f assembly language source. the compiler also supports many command line options and language extensions to take full advantage of the dspic30f device hardware capabili- ties and afford fine control of the compiler code generator. mplab c30 is distributed with a complete ansi c standard library. all library functions have been vali- dated and conform to the ansi c library standard. the library includes functions for string manipulation, dynamic memory allocation, data conversion, time- keeping and math functions (trigonometric, exponential and hyperbolic). the compiler provides symbolic information for high-level source debugging with the mplab ide. 25.6 mplab asm30 assembler, linker and librarian mplab asm30 assembler produces relocatable machine code from symbolic assembly language for dspic30f devices. mplab c30 compiler uses the assembler to produce it?s object file. the assembler generates relocatable object files that can then be archived or linked with other relocatable object files and archives to create an executable file. notable features of the assembler include: support for the entire dspic30f instruction set support for fixed-point and floating-point data command line interface rich directive set flexible macro language mplab ide compatibility 25.7 mplab sim software simulator the mplab sim software simulator allows code devel- opment in a pc hosted environment by simulating the picmicro series microcontrollers on an instruction level. on any given instruction, the data areas can be examined or modified and stimuli can be applied from a file, or user defined key press, to any pin. the execu- tion can be performed in single-step, execute until break or trace mode. the mplab sim simulator fully supports symbolic debugging using the mplab c17 and mplab c18 c compilers, as well as the mpasm assembler. the software simulator offers the flexibility to develop and debug code outside of the laboratory environment, making it an excellent, economical software development tool. 25.8 mplab sim30 software simulator the mplab sim30 software simulator allows code development in a pc hosted environment by simulating the dspic30f series microcontrollers on an instruction level. on any given instruction, the data areas can be examined or modified and stimuli can be applied from a file, or user defined key press, to any of the pins. the mplab sim30 simulator fully supports symbolic debugging using the mplab c30 c compiler and mplab asm30 assembler. the simulator runs in either a command line mode for automated tasks, or from mplab ide. this high-speed simulator is designed to debug, analyze and optimize time intensive dsp routines.
? 2004 microchip technology inc. ds39609b-page 303 pic18f6520/8520/6620/8620/6720/8720 25.9 mplab ice 2000 high-performance universal in-circuit emulator the mplab ice 2000 universal in-circuit emulator is intended to provide the product development engineer with a complete microcontroller design tool set for picmicro microcontrollers. software control of the mplab ice 2000 in-circuit emulator is advanced by the mplab integrated development environment, which allows editing, building, downloading and source debugging from a single environment. the mplab ice 2000 is a full-featured emulator sys- tem with enhanced trace, trigger and data monitoring features. interchangeable processor modules allow the system to be easily reconfigured for emulation of differ- ent processors. the universal architecture of the mplab ice in-circuit emulator allows expansion to support new picmicro microcontrollers. the mplab ice 2000 in-circuit emulator system has been designed as a real-time emulation system with advanced features that are typically found on more expensive development tools. the pc platform and microsoft ? windows 32-bit operating system were chosen to best make these features available in a simple, unified application. 25.10 mplab ice 4000 high-performance universal in-circuit emulator the mplab ice 4000 universal in-circuit emulator is intended to provide the product development engineer with a complete microcontroller design tool set for high- end picmicro microcontrollers. software control of the mplab ice in-circuit emulator is provided by the mplab integrated development environment, which allows editing, building, downloading and source debugging from a single environment. the mplab icd 4000 is a premium emulator system, providing the features of mplab ice 2000, but with increased emulation memory and high-speed perfor- mance for dspic30f and pic18xxxx devices. its advanced emulator features include complex triggering and timing, up to 2 mb of emulation memory and the ability to view variables in real-time. the mplab ice 4000 in-circuit emulator system has been designed as a real-time emulation system with advanced features that are typically found on more expensive development tools. the pc platform and microsoft windows 32-bit operating system were chosen to best make these features available in a simple, unified application. 25.11 mplab icd 2 in-circuit debugger microchip?s in-circuit debugger, mplab icd 2, is a powerful, low-cost, run-time development tool, connecting to the host pc via an rs-232 or high-speed usb interface. this tool is based on the flash picmicro mcus and can be used to develop for these and other picmicro microcontrollers. the mplab icd 2 utilizes the in-circuit debugging capability built into the flash devices. this feature, along with microchip?s in-circuit serial programming tm (icsp tm ) protocol, offers cost effective in-circuit flash debugging from the graphical user interface of the mplab integrated development environment. this enables a designer to develop and debug source code by setting breakpoints, single-stepping and watching variables, cpu status and peripheral registers. running at full speed enables testing hardware and applications in real-time. mplab icd 2 also serves as a development programmer for selected picmicro devices. 25.12 pro mate ii universal device programmer the pro mate ii is a universal, ce compliant device programmer with programmable voltage verification at v ddmin and v ddmax for maximum reliability. it features an lcd display for instructions and error messages and a modular detachable socket assembly to support various package types. in stand-alone mode, the pro mate ii device programmer can read, verify and program picmicro devices without a pc connection. it can also set code protection in this mode. 25.13 mplab pm3 device programmer the mplab pm3 is a universal, ce compliant device programmer with programmable voltage verification at v ddmin and v ddmax for maximum reliability. it features a large lcd display (128 x 64) for menus and error messages and a modular detachable socket assembly to support various package types. the icsp? cable assembly is included as a standard item. in stand- alone mode, the mplab pm3 device programmer can read, verify and program picmicro devices without a pc connection. it can also set code protection in this mode. mplab pm3 connects to the host pc via an rs-232 or usb cable. mplab pm3 has high-speed communications and optimized algorithms for quick programming of large memory devices and incorpo- rates an sd/mmc card for file storage and secure data applications.
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 304 ? 2004 microchip technology inc. 25.14 picstart plus development programmer the picstart plus development programmer is an easy-to-use, low-cost, prototype programmer. it con- nects to the pc via a com (rs-232) port. mplab integrated development environment software makes using the programmer simple and efficient. the picstart plus development programmer supports most picmicro devices up to 40 pins. larger pin count devices, such as the pic16c92x and pic17c76x, may be supported with an adapter socket. the picstart plus development programmer is ce compliant. 25.15 picdem 1 picmicro demonstration board the picdem 1 demonstration board demonstrates the capabilities of the pic16c5x (pic16c54 to pic16c58a), pic16c61, pic16c62x, pic16c71, pic16c8x, pic17c42, pic17c43 and pic17c44. all necessary hardware and software is included to run basic demo programs. the sample microcontrollers provided with the picdem 1 demonstration board can be programmed with a pro mate ii device program- mer or a picstart plus development programmer. the picdem 1 demonstration board can be connected to the mplab ice in-circuit emulator for testing. a prototype area extends the circuitry for additional appli- cation components. features include an rs-232 interface, a potentiometer for simulated analog input, push button switches and eight leds. 25.16 picdem.net internet/ethernet demonstration board the picdem.net demonstration board is an internet/ ethernet demonstration board using the pic18f452 microcontroller and tcp/ip firmware. the board supports any 40-pin dip device that conforms to the standard pinout used by the pic16f877 or pic18c452. this kit features a user friendly tcp/ip stack, web server with html, a 24l256 serial eeprom for xmodem download to web pages into serial eeprom, icsp/mplab icd 2 interface con- nector, an ethernet interface, rs-232 interface and a 16 x 2 lcd display. also included is the book and cd-rom ?tcp/ip lean, web servers for embedded systems,? by jeremy bentham 25.17 picdem 2 plus demonstration board the picdem 2 plus demonstration board supports many 18, 28 and 40-pin microcontrollers, including pic16f87x and pic18fxx2 devices. all the neces- sary hardware and software is included to run the dem- onstration programs. the sample microcontrollers provided with the picdem 2 demonstration board can be programmed with a pro mate ii device program- mer, picstart plus development programmer, or mplab icd 2 with a universal programmer adapter. the mplab icd 2 and mplab ice in-circuit emulators may also be used with the picdem 2 demonstration board to test firmware. a prototype area extends the circuitry for additional application components. some of the features include an rs-232 interface, a 2 x 16 lcd display, a piezo speaker, an on-board temperature sensor, four leds and sample pic18f452 and pic16f877 flash microcontrollers. 25.18 picdem 3 pic16c92x demonstration board the picdem 3 demonstration board supports the pic16c923 and pic16c924 in the plcc package. all the necessary hardware and software is included to run the demonstration programs. 25.19 picdem 4 8/14/18-pin demonstration board the picdem 4 can be used to demonstrate the capa- bilities of the 8, 14 and 18-pin pic16xxxx and pic18xxxx mcus, including the pic16f818/819, pic16f87/88, pic16f62xa and the pic18f1320 family of microcontrollers. picdem 4 is intended to showcase the many features of these low pin count parts, including lin and motor control using eccp. special provisions are made for low-power operation with the supercapacitor circuit and jumpers allow on- board hardware to be disabled to eliminate current draw in this mode. included on the demo board are pro- visions for crystal, rc or canned oscillator modes, a five volt regulator for use with a nine volt wall adapter or battery, db-9 rs-232 interface, icd connector for programming via icsp and development with mplab icd 2, 2 x 16 liquid crystal display, pcb footprints for h-bridge motor driver, lin transceiver and eeprom. also included are: header for expansion, eight leds, four potentiometers, three push buttons and a proto- typing area. included with the kit is a pic16f627a and a pic18f1320. tutorial firmware is included along with the user?s guide.
? 2004 microchip technology inc. ds39609b-page 305 pic18f6520/8520/6620/8620/6720/8720 25.20 picdem 17 demonstration board the picdem 17 demonstration board is an evaluation board that demonstrates the capabilities of several microchip microcontrollers, including pic17c752, pic17c756a, pic17c762 and pic17c766. a pro- grammed sample is included. the pro mate ii device programmer, or the picstart plus development pro- grammer, can be used to reprogram the device for user tailored application development. the picdem 17 demonstration board supports program download and execution from external on-board flash memory. a generous prototype area is available for user hardware expansion. 25.21 picdem 18r pic18c601/801 demonstration board the picdem 18r demonstration board serves to assist development of the pic18c601/801 family of microchip microcontrollers. it provides hardware implementation of both 8-bit multiplexed/demultiplexed and 16-bit memory modes. the board includes 2 mb external flash memory and 128 kb sram memory, as well as serial eeprom, allowing access to the wide range of memory types supported by the pic18c601/801. 25.22 picdem lin pic16c43x demonstration board the powerful lin hardware and software kit includes a series of boards and three picmicro microcontrollers. the small footprint pic16c432 and pic16c433 are used as slaves in the lin communication and feature on-board lin transceivers. a pic16f874 flash microcontroller serves as the master. all three micro- controllers are programmed with firmware to provide lin bus communication. 25.23 pickit tm 1 flash starter kit a complete ?development system in a box?, the pickit flash starter kit includes a convenient multi-section board for programming, evaluation and development of 8/14-pin flash pic ? microcontrollers. powered via usb, the board operates under a simple windows gui. the pickit 1 starter kit includes the user?s guide (on cd rom), pickit 1 tutorial software and code for various applications. also included are mplab ? ide (integrated development environment) software, software and hardware ?tips 'n tricks for 8-pin flash pic ? microcontrollers? handbook and a usb interface cable. supports all current 8/14-pin flash pic microcontrollers, as well as many future planned devices. 25.24 picdem usb pic16c7x5 demonstration board the picdem usb demonstration board shows off the capabilities of the pic16c745 and pic16c765 usb microcontrollers. this board provides the basis for future usb products. 25.25 evaluation and programming tools in addition to the picdem series of circuits, microchip has a line of evaluation kits and demonstration software for these products. k ee l oq evaluation and programming tools for microchip?s hcs secure data products can developers kit for automotive network applications analog design boards and filter design software powersmart battery charging evaluation/ calibration kits irda ? development kit microid development and rflab tm development software seeval ? designer kit for memory evaluation and endurance calculations picdem msc demo boards for switching mode power supply, high-power ir driver, delta sigma adc and flow rate sensor check the microchip web page and the latest product selector guide for the complete list of demonstration and evaluation kits.
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 306 ? 2004 microchip technology inc. notes:
? 2004 microchip technology inc. ds39609b-page 307 pic18f6520/8520/6620/8620/6720/8720 26.0 electrical characteristics absolute maximum ratings (?) ambient temperature under bias................................................................................................. ............-55c to +125c storage temperature ............................................................................................................ .................. -65c to +150c voltage on any pin with respect to v ss (except v dd , mclr and ra4) .......................................... -0.3v to (v dd + 0.3v) voltage on v dd with respect to v ss ......................................................................................................... -0.3v to +5.5v voltage on mclr with respect to v ss (note 2) ......................................................................................... 0v to +13.25v voltage on ra4 with respect to vss ............................................................................................. .................. 0v to +8.5v total power dissipation (note 1) ............................................................................................................................... 1.0w maximum current out of v ss pin ........................................................................................................................... 300 ma maximum current into v dd pin ........................................................................................................................... ...250 ma input clamp current, i ik (v i < 0 or v i > v dd ) ...................................................................................................................... 20 ma output clamp current, i ok (v o < 0 or v o > v dd ) .............................................................................................................. 20 ma maximum output current sunk by any i/o pin..................................................................................... .....................25 ma maximum output current sourced by any i/o pin .................................................................................. ..................25 ma maximum current sunk by all ports ...................................................................................................................... .200 ma maximum current sourced by all ports ........................................................................................... .......................200 ma note 1: power dissipation is calculated as follows: pdis = v dd x {i dd ? i oh } + {(v dd ? v oh ) x i oh } + (v ol x i ol ) 2: voltage spikes below v ss at the mclr /v pp pin, inducing currents greater than 80 ma, may cause latch-up. thus, a series resistor of 50-100 ? should be used when applying a ?low? level to the mclr /v pp pin, rather than pulling this pin directly to v ss . ? notice: stresses above those listed under ?absolute maximum ratings? may cause permanent damage to the device. this is a stress rating only and functional operation of the device at those or any other conditions above those indicated in the operation listings of this specification is not implied. exposure to maximum rating conditions for extended periods may affect device reliability.
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 308 ? 2004 microchip technology inc. figure 26-1: pic18f6520/8520 voltage-frequency graph (industrial, extended) figure 26-2: pic18lf6520/8520 voltage-frequency graph (industrial) frequency voltage 6.0v 5.5v 4.5v 4.0v 2.0v f max 5.0v 3.5v 3.0v 2.5v 4.2v f max (extended) pic18fx520 f max = 40 mhz for pic18f6520/8520 in microcontroller mode. f max (extended) = 25 mhz for pic18f6520/8520 in modes other than microcontroller mode. frequency voltage 6.0v 5.5v 4.5v 4.0v 2.0v f max 5.0v 3.5v 3.0v 2.5v pic18lfx520 for pic18f6520/8520 in microcontroller mode: 4 mhz 4.2v f max = (16.36 mhz/v) (v ddappmin ? 2.0v) + 4 mhz, if v ddappmin 4.2v; f max = 40 mhz, if v ddappmin > 4.2v. for pic18f8x8x in modes other than microcontroller mode: f max = (9.55 mhz/v) (v ddappmin ? 2.0v) + 4 mhz, if v ddappmin 4.2v; f max = 25 mhz, if v ddappmin > 4.2v. note: v ddappmin is the minimum voltage of the picmicro ? device in the application.
? 2004 microchip technology inc. ds39609b-page 309 pic18f6520/8520/6620/8620/6720/8720 figure 26-3: pic18f6620/6720/8620/8720 voltage-frequency graph (industrial, extended) figure 26-4: pic18lf6620/6720/8620/8720 voltage-frequency graph (industrial) frequency voltage 6.0v 5.5v 4.5v 4.0v 2.0v f max 5.0v 3.5v 3.0v 2.5v pic18fx620/x720 4.2v f max (extended) f max = 25 mhz in microcontroller mode. f max (extended) = 16 mhz for pic18f6520/8520 in modes other than microcontroller mode. frequency voltage 6.0v 5.5v 4.5v 4.0v 2.0v f max 5.0v 3.5v 3.0v 2.5v pic18lfx620/x720 4 mhz 4.2v in microcontroller mode: f max = (9.55 mhz/v) (v ddappmin ? 2.0v) + 4 mhz, if v ddappmin 4.2v; f max = 25 mhz, if v ddappmin > 4.2v. in modes other than microcontroller mode: f max = (5.45 mhz/v) (v ddappmin ? 2.0v) + 4 mhz, if v ddappmin 4.2v; f max = 16 mhz, if v ddappmin > 4.2v. note: v ddappmin is the minimum voltage of the picmicro ? device in the application.
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 310 ? 2004 microchip technology inc. 26.1 dc characteristics: supply voltage pic18f6520/8520/6620/8620/6720/8720 (industrial, extended) pic18lf6520/8520/6620/8620/6720/8720 (industrial) pic18lf6520/8520/6620/8620/6720/8720 (industrial) standard operating conditions (unless otherwise stated) operating temperature -40c t a +85c for industrial pic18f6520/8520/6620/8620/6720/8720 (industrial, extended) standard operating conditions (unless otherwise stated) operating temperature -40c t a +85c for industrial -40c t a +125c for extended param no. symbol characteristic min typ max units conditions d001 v dd supply voltage pic18lfxx20 2.0 ? 5.5 v hs, xt, rc and lp oscillator mode pic18fxx20 4.2 ? 5.5 v d001a av dd analog supply voltage v dd ? 0.3 ? v dd + 0.3 v d002 v dr ram data retention voltage (1) 1.5 ? ? v d003 v por v dd start voltage to ensure internal power-on reset signal ? ? 0.7 v see section on power-on reset for details d004 s vdd v dd rise rate to ensure internal power-on reset signal 0.05 ? ? v/ms see section on power-on reset for details d005 v bor brown-out reset voltage borv1:borv0 = 11 n/a ? n/a v reserved borv1:borv0 = 10 2.64 ? 2.92 v borv1:borv0 = 01 4.11 ? 4.55 v borv1:borv0 = 00 4.41 ? 4.87 v legend: shading of rows is to assist in readability of the table. note 1: this is the limit to which v dd can be lowered in sleep mode, or duri ng a device reset, without losing ram data.
? 2004 microchip technology inc. ds39609b-page 311 pic18f6520/8520/6620/8620/6720/8720 26.2 dc characteristics: power-down and supply current pic18f6520/8520/6620/8620/6720/8720 (industrial, extended) pic18lf6520/8520/6620/8620/6720/8720 (industrial) pic18lf6520/8520/6620/8620/6720/8720 (industrial) standard operating conditions (unless otherwise stated) operating temperature -40c t a +85c for industrial pic18f6520/8520/6620/8620/6720/8720 (industrial, extended) standard operating conditions (unless otherwise stated) operating temperature -40c t a +85c for industrial -40c t a +125c for extended param no. device typ max units conditions power-down current (i pd ) (1) pic18lfxx20 0.2 1 a -40c v dd = 2.0v, (sleep mode) 0.2 1 a +25c 1.2 5 a +85c pic18lfxx20 0.4 1 a -40c v dd = 3.0v, (sleep mode) 0.4 1 a +25c 1.8 8 a +85c all devices 0.7 2 a -40c v dd = 5.0v, (sleep mode) 0.7 2 a +25c 3.0 15 a +85c legend: shading of rows is to assist in readability of the table. note 1: the power-down current in sleep mode does not depend on the oscillator type. power-down current is measured with the part in sleep mode, with all i/o pins in high-impedance state and tied to v dd or v ss and all features that add delta current disabled (such as wdt, timer1 oscillator, bor, etc.). 2: the supply current is mainly a function of operating voltage, frequency and mode. other factors, such as i/o pin loading and switching rate, oscillator type and circuit, internal code execution pattern and temperature, also have an impact on the current consumption. the test conditions for all i dd measurements in active operation mode are: osc1 = external square wave, from rail-to-ra il; all i/o pins tri-stated, pulled to v dd ; mclr = v dd ; wdt enabled/disabled as specified. 3: for rc oscillator configurations, current through r ext is not included. the current through the resistor can be estimated by the formula ir = v dd /2r ext (ma) with r ext in k ? .
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 312 ? 2004 microchip technology inc. supply current (i dd ) (2,3) pic18lfxx20 165 350 a -40c v dd = 2.0v f osc = 1 mh z , ec oscillator 165 350 a +25c 170 350 a +85c pic18lfxx20 360 750 a -40c v dd = 3.0v 340 750 a +25c 300 750 a +85c all devices 800 1700 a -40c v dd = 5.0v 730 1700 a +25c 700 1700 a +85c pic18lfxx20 600 1200 a -40c v dd = 2.0v f osc = 4 mhz, ec oscillator 600 1200 a +25c 640 1300 a +85c pic18lfxx20 1000 2500 a -40c v dd = 3.0v 1000 2500 a +25c 1000 2500 a +85c all devices 2.2 5.0 ma -40c v dd = 5.0v 2.1 5.0 ma +25c 2.0 5.0 ma +85c 26.2 dc characteristics: power-down and supply current pic18f6520/8520/6620/8620/6720/8720 (industrial, extended) pic18lf6520/8520/6620/8620/6720/8720 (industrial) (continued) pic18lf6520/8520/6620/8620/6720/8720 (industrial) standard operating conditions (unless otherwise stated) operating temperature -40c t a +85c for industrial pic18f6520/8520/6620/8620/6720/8720 (industrial, extended) standard operating conditions (unless otherwise stated) operating temperature -40c t a +85c for industrial -40c t a +125c for extended param no. device typ max units conditions legend: shading of rows is to assist in readability of the table. note 1: the power-down current in sleep mode does not depend on the oscillator type. power-down current is measured with the part in sleep mode, with all i/o pins in high-impedance state and tied to v dd or v ss and all features that add delta current disabled (such as wdt, timer1 oscillator, bor, etc.). 2: the supply current is mainly a function of operating voltage, frequency and mode. other factors, such as i/o pin loading and switching rate, oscillator type and circuit, internal code execution pattern and temperature, also have an impact on the current consumption. the test conditions for all i dd measurements in active operation mode are: osc1 = external square wave, from rail-to-ra il; all i/o pins tri-stated, pulled to v dd ; mclr = v dd ; wdt enabled/disabled as specified. 3: for rc oscillator configurations, current through r ext is not included. the current through the resistor can be estimated by the formula ir = v dd /2r ext (ma) with r ext in k ? .
? 2004 microchip technology inc. ds39609b-page 313 pic18f6520/8520/6620/8620/6720/8720 supply current (i dd ) (2,3) pic18fx620, pic18fx720 9.3 15 ma -40c v dd = 4.2v f osc = 25 mh z , ec oscillator 9.5 15 ma +25c 10 15 ma +85c pic18fx620, pic18fx720 11.8 20 ma -40c v dd = 5.0v 12 20 ma +25c 12 20 ma +85c pic18fx520 16 20 ma -40c v dd = 4.2v f osc = 40 mh z , ec oscillator 16 20 ma +25c 16 20 ma +85c pic18fx520 19 25 ma -40c v dd = 5.0v 19 25 ma +25c 19 25 ma +85c d014 pic18fx620/x720 15 55 a -40c to +85c v dd = 2.0v f osc = 32 khz, timer1 as clock pic18lf8520 13 18 a -40c to +85c v dd = 2.0v f osc = 32 khz, timer1 as clock 20 35 a -40c to +85c v dd = 3.0v 50 85 a -40c to +85c v dd = 5.0v pic18fxx20 ? 200 a -40c to +85c v dd = 4.2v f osc = 32 khz, timer1 as clock ? 250 a -40c to +125c v dd = 4.2v 26.2 dc characteristics: power-down and supply current pic18f6520/8520/6620/8620/6720/8720 (industrial, extended) pic18lf6520/8520/6620/8620/6720/8720 (industrial) (continued) pic18lf6520/8520/6620/8620/6720/8720 (industrial) standard operating conditions (unless otherwise stated) operating temperature -40c t a +85c for industrial pic18f6520/8520/6620/8620/6720/8720 (industrial, extended) standard operating conditions (unless otherwise stated) operating temperature -40c t a +85c for industrial -40c t a +125c for extended param no. device typ max units conditions legend: shading of rows is to assist in readability of the table. note 1: the power-down current in sleep mode does not depend on the oscillator type. power-down current is measured with the part in sleep mode, with all i/o pins in high-impedance state and tied to v dd or v ss and all features that add delta current disabled (such as wdt, timer1 oscillator, bor, etc.). 2: the supply current is mainly a function of operating voltage, frequency and mode. other factors, such as i/o pin loading and switching rate, oscillator type and circuit, internal code execution pattern and temperature, also have an impact on the current consumption. the test conditions for all i dd measurements in active operation mode are: osc1 = external square wave, from rail-to-ra il; all i/o pins tri-stated, pulled to v dd ; mclr = v dd ; wdt enabled/disabled as specified. 3: for rc oscillator configurations, current through r ext is not included. the current through the resistor can be estimated by the formula ir = v dd /2r ext (ma) with r ext in k ? .
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 314 ? 2004 microchip technology inc. module differential currents ( ? i wdt , ? i bor , ? i lvd , ? i oscb , ? i ad ) d022 ( ? i wdt ) watchdog timer <1 2.0 a-40 c v dd = 2.0v <1 1.5 a+25 c <1 3 a+85 c 310 a-40 c v dd = 3.0v 2.5 6 a+25 c 315 a+85 c 15 25 a-40 c v dd = 5.0v 12 20 a+25 c 12 40 a+85 c d022a ( ? i bor ) brown-out reset 35 50 a-40 c to +85 cv dd = 3.0v 45 65 a-40 c to +85 cv dd = 5.0v d022b ( ? i lvd ) low-voltage detect 33 45 a-40 c to +85 cv dd = 2.0v 35 50 a-40 c to +85 cv dd = 3.0v 45 65 a-40 c to +85 cv dd = 5.0v d025 ( ? i oscb ) timer1 oscillator 5.2 30 a+25 cv dd = 2.0v 32 khz on timer1 pic18lf8720/8620 5.2 40 a-40 c to +85 cv dd = 2.0v 6.5 50 a-40 c to +125 cv dd = 4.2v pic18f8520/8620/8720 6.5 40 a +25 c v dd = 4.2v 32 khz on timer1 6.5 50 a -40 c to +85 c 6.5 65 a -40 c to +125 c pic18lf8520 1.8 2.2 a+25 cv dd = 2.0v 32 khz on timer1 2.9 3.8 a-40 c to +85 cv dd = 3.0v 3.4 7.0 a-40 c to +125 cv dd = 5.0v d026 ( ? i ad ) a/d converter <1 2 a +25 cv dd = 2.0v a/d on, not converting. device is in sleep. <1 2 a +25 cv dd = 3.0v <1 2 a +25 cv dd = 5.0v 26.2 dc characteristics: power-down and supply current pic18f6520/8520/6620/8620/6720/8720 (industrial, extended) pic18lf6520/8520/6620/8620/6720/8720 (industrial) (continued) pic18lf6520/8520/6620/8620/6720/8720 (industrial) standard operating conditions (unless otherwise stated) operating temperature -40c t a +85c for industrial pic18f6520/8520/6620/8620/6720/8720 (industrial, extended) standard operating conditions (unless otherwise stated) operating temperature -40c t a +85c for industrial -40c t a +125c for extended param no. device typ max units conditions legend: shading of rows is to assist in readability of the table. note 1: the power-down current in sleep mode does not depend on the oscillator type. power-down current is measured with the part in sleep mode, with all i/o pins in high-impedance state and tied to v dd or v ss and all features that add delta current disabled (such as wdt, timer1 oscillator, bor, etc.). 2: the supply current is mainly a function of operating voltage, frequency and mode. other factors, such as i/o pin loading and switching rate, oscillator type and circuit, internal code execution pattern and temperature, also have an impact on the current consumption. the test conditions for all i dd measurements in active operation mode are: osc1 = external square wave, from rail-to-ra il; all i/o pins tri-stated, pulled to v dd ; mclr = v dd ; wdt enabled/disabled as specified. 3: for rc oscillator configurations, current through r ext is not included. the current through the resistor can be estimated by the formula ir = v dd /2r ext (ma) with r ext in k ? .
? 2004 microchip technology inc. ds39609b-page 315 pic18f6520/8520/6620/8620/6720/8720 26.3 dc characteristics: pic18f6520/8520/6620/8620/6720/8720 (industrial, extended) pic18lf6520/8520/6620/8620/6720/8720 (industrial) dc characteristics standard operating conditions (unless otherwise stated) operating temperature -40c t a +85c for industrial -40c t a +125c for extended param no. sym characteristic min max units conditions v il input low voltage i/o ports: d030 with ttl buffer v ss 0.15 v dd vv dd < 4.5v d030a ? 0.8 v 4.5v v dd 5.5v d031 with schmitt trigger buffer rc3 and rc4 v ss v ss 0.2 v dd 0.3 v dd v v d032 mclr v ss 0.2 v dd v d032a osc1 (in xt, hs and lp modes) and t1osi v ss 0.2 v dd v d033 osc1 (in rc and ec mode) (1) v ss 0.2 v dd v v ih input high voltage i/o ports: d040 with ttl buffer 0.25 v dd + 0.8v v dd vv dd < 4.5v d040a 2.0 v dd v4.5v v dd 5.5v d041 with schmitt trigger buffer rc3 and rc4 0.8 v dd 0.7 v dd v dd v dd v v d042 mclr , osc1 (ec mode) 0.8 v dd v dd v d042a osc1 and t1osi 1.6 v dd v lp, xt, hs, hspll modes (1) d043 osc1 (rc mode) (1) 0.9 v dd v dd v i il input leakage current (2,3) d060 i/o ports ? 1 av ss v pin v dd , pin at high-impedance d061 mclr ? 5 av ss v pin v dd d063 osc1 ? 5 av ss v pin v dd i pu weak pull-up current d070 i purb portb weak pull-up current 50 400 av dd = 5v, v pin = v ss note 1: in rc oscillator configuration, the osc1/clki pin is a schmitt trigger input. it is not recommended that the picmicro device be driven with an external clock while in rc mode. 2: the leakage current on the mclr pin is strongly dependent on the applied voltage level. the specified levels represent normal operating conditions. higher leakage current may be measured at different input voltages. 3: negative current is defined as current sourced by the pin. 4: parameter is characterized but not tested.
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 316 ? 2004 microchip technology inc. v ol output low voltage d080 i/o ports ? 0.6 v i ol = 8.5 ma, v dd = 4.5v, -40 c to +85 c d080a ? 0.6 v i ol = 7.0 ma, v dd = 4.5v, -40 c to +125 c d083 osc2/clko (rc mode) ?0.6vi ol = 1.6 ma, v dd = 4.5v, -40 c to +85 c d083a ? 0.6 v i ol = 1.2 ma, v dd = 4.5v, -40 c to +125 c v oh output high voltage (3) d090 i/o ports v dd ? 0.7 ? v i oh = -3.0 ma, v dd = 4.5v, -40 c to +85 c d090a v dd ? 0.7 ? v i oh = -2.5 ma, v dd = 4.5v, -40 c to +125 c d092 osc2/clko (rc mode) v dd ? 0.7 ? v i oh = -1.3 ma, v dd = 4.5v, -40 c to +85 c d092a v dd ? 0.7 ? v i oh = -1.0 ma, v dd = 4.5v, -40 c to +125 c d150 v od open-drain high voltage ? 8.5 v ra4 pin capacitive loading specs on output pins d100 (4) c osc2 osc2 pin ? 15 pf in xt, hs and lp modes when external clock is used to drive osc1 d101 c io all i/o pins and osc2 (in rc mode) ? 50 pf to meet the ac timing specifications d102 c b scl, sda ? 400 pf in i 2 c mode 26.3 dc characteristics: pic18f6520/8520/6620/8620/6720/8720 (industrial, extended) pic18lf6520/8520/6620/8620/6720/8720 (industrial) (continued) dc characteristics standard operating conditions (unless otherwise stated) operating temperature -40c t a +85c for industrial -40c t a +125c for extended param no. sym characteristic min max units conditions note 1: in rc oscillator configuration, the osc1/clki pin is a schmitt trigger input. it is not recommended that the picmicro device be driven with an external clock while in rc mode. 2: the leakage current on the mclr pin is strongly dependent on the applied voltage level. the specified levels represent normal operating conditions. higher leakage current may be measured at different input voltages. 3: negative current is defined as current sourced by the pin. 4: parameter is characterized but not tested.
? 2004 microchip technology inc. ds39609b-page 317 pic18f6520/8520/6620/8620/6720/8720 table 26-1: comparator specifications table 26-2: voltage reference specifications operating conditions: 3.0v < v dd < 5.5v, -40c < t a < +125c (unless otherwise stated). param no. sym characteristics min typ max units comments d300 v ioff input offset voltage ? 5.0 10 mv d301 v icm input common mode voltage 0 ? v dd ? 1.5 v d302 cmrr common mode rejection ratio 55 ? ? db 300 300a t resp response time (1) ? 150 400 600 ns ns pic18fxx20 pic18lfxx20 301 t mc 2 ov comparator mode change to output valid ?? 10 s note 1: response time measured with one comparator input at (v dd ? 1.5)/2, while the other input transitions from v ss to v dd . operating conditions: 3.0v < v dd < 5.5v, -40c < t a < +125c (unless otherwise stated). param no. sym characteristics min typ max units comments d310 v res resolution v dd /24 ? v dd /32 lsb d311 v raa absolute accuracy ? ? ? ? 1/4 1/2 lsb lsb low range (vrr = 1 ) high range (vrr = 0 ) d312 v rur unit resistor value (r) ? 2k ? ? 310 t set settling time (1) ? ? 10 s note 1: settling time measured while vrr = 1 and vr<3:0> transitions from ? 0000 ? to ? 1111 ?.
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 318 ? 2004 microchip technology inc. figure 26-5: low-voltage detect characteristics table 26-3: low-voltage detect characteristics v lvd lvdif v dd (lvdif set by hardware) (lvdif can be cleared in software) standard operating conditions (unless otherwise stated) operating temperature -40c t a +85c for industrial -40c t a +125c for extended param no. symbol characteristic min typ? max units conditions d420 lvd voltage on v dd transition high-to-low lvv = 0001 1.96 2.06 2.16 v lvv = 0010 2.16 2.27 2.38 v lvv = 0011 2.35 2.47 2.59 v lvv = 0100 2.45 2.58 2.71 v lvv = 0101 2.64 2.78 2.92 v lvv = 0110 2.75 2.89 3.03 v lvv = 0111 2.95 3.1 3.26 v lvv = 1000 3.24 3.41 3.58 v lvv = 1001 3.43 3.61 3.79 v lvv = 1010 3.53 3.72 3.91 v lvv = 1011 3.72 3.92 4.12 v lvv = 1100 3.92 4.13 4.34 v lvv = 1101 4.11 4.33 4.55 v lvv = 1110 4.41 4.64 4.87 v d423 v bg band gap reference voltage value ? 1.22 ? v ? production tested at t amb = 25c. specifications over temperature limits ensured by characterization.
? 2004 microchip technology inc. ds39609b-page 319 pic18f6520/8520/6620/8620/6720/8720 table 26-4: memory programming requirements dc characteristics standard operating conditions (unless otherwise stated) operating temperature -40c t a +85c for industrial -40c t a +125c for extended param no. sym characteristic min typ? max units conditions internal program memory programming specifications (note 1) d110 v pp voltage on mclr /v pp pin 9.00 ? 13.25 v (note 2) d112 i pp current into mclr /v pp pin ? ? 5 a d113 i ddp supply current during programming ??10ma data eeprom memory d120 e d cell endurance 100k 1m ? e/w -40 c to +85 c d120a e d cell endurance 10k 100k ? e/w +85 c to +125 c d121 v drw v dd for read/write v min ? 5.5 v using eecon to read/write v min = minimum operating voltage d122 t dew erase/write cycle time ? 4 ? ms d123 t retd characteristic retention 40 ? ? year -40 c to +85 c (note 3) d123a t retd characteristic retention 100 ? ? year 25 c (note 3) program flash memory d130 e p cell endurance 10k 100k ? e/w -40 c to +85 c d130a e p cell endurance 1000 10k ? e/w +85 c to +125 c d131 v pr v dd for read v min ?5.5vv min = minimum operating voltage d132 v ie v dd for block erase 4.5 ? 5.5 v using icsp port d132a v iw v dd for externally timed erase or write 4.5 ? 5.5 v using icsp port d132b v pew v dd for self-timed write v min ?5.5vv min = minimum operating voltage d133 t ie icsp block erase cycle time ? 5 ? ms v dd > 4.5v d133a t iw icsp erase or write cycle time (externally timed) 1??msv dd > 4.5v d133a t iw self-timed write cycle time ? 2.5 ? ms d134 t retd characteristic retention 40 ? ? year -40 c to +85 c (note 3) d134a t retd characteristic retention 100 ? ? year 25 c (note 3) ? data in ?typ? column is at 5.0v, 25c unless otherwise stated. these parameters are for design guidance only and are not tested. note 1: these specifications are for programming the on-chip program memory through the use of table write instructions. 2: the pin may be kept in this range at times other than programming, but it is not recommended. 3: retention time is valid, provided no other specifications are violated.
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 320 ? 2004 microchip technology inc. 26.4 ac (timing) characteristics 26.4.1 timing parameter symbology the timing parameter symbols have been created using one of the following formats: 1. tpps2pps 3. t cc : st (i 2 c specifications only) 2. tpps 4. ts (i 2 c specifications only) t f frequency t time lowercase letters (pp) and their meanings: pp cc ccp1 osc osc1 ck clko rd rd cs cs rw rd or wr di sdi sc sck do sdo ss ss dt data in t0 t0cki io i/o port t1 t1cki mc mclr wr wr uppercase letters and their meanings: s f fall p period hhigh rrise i invalid (high-impedance) v valid l low z high-impedance i 2 c only aa output access high high buf bus free low low t cc : st (i 2 c specifications only) cc hd hold su setup st dat data input hold sto stop condition sta start condition
? 2004 microchip technology inc. ds39609b-page 321 pic18f6520/8520/6620/8620/6720/8720 26.4.2 timing conditions the temperature and voltages specified in table 26-5 apply to all timing specifications unless otherwise noted. figure 26-6 specifies the load conditions for the timing specifications. table 26-5: temperature and voltage specifications ? ac figure 26-6: load conditions for devi ce timing specifications ac characteristics standard operating conditions (unless otherwise stated) operating temperature -40c t a +85c for industrial -40c t a +125c for extended operating voltage v dd range as described in dc spec section 26.1 and section 26.3 . lc parts operate for industrial temperatures only. v dd /2 c l r l pin pin v ss v ss c l r l = 464 ? c l = 50 pf for all pins except osc2/clko and including d and e outputs as ports load condition 1 load condition 2
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 322 ?
? 2004 microchip technology inc. ds39609b-page 323 pic18f6520/8520/6620/8620/6720/8720 table 26-7: pll clock timing specifications (v dd = 4.2v to 5.5v) figure 26-8: clko and i/o timing param no. sym characteristic min typ? max units conditions ?f osc oscillator frequency range 4 ? 10 mhz hs mode ?f sys on-chip vco system frequency 16 ? 40 mhz hs mode ?t rc pll start-up time (lock time) ? ? 2 ms ? ? clk clko stability (jitter) -2 ? +2 % ? data in ?typ? column is at 5v, 25 c, unless otherwise stated. these parameters are for design guidance only and are not tested. note: refer to figure 26-6 for load conditions. osc1 clko i/o pin (input) i/o pin (output) q4 q1 q2 q3 10 13 14 17 20, 21 19 18 15 11 12 16 old value new value
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 324 ? 2004 microchip technology inc. table 26-8: clko and i/o timing requirements figure 26-9: program memo ry read timing diagram param no. symbol characteristic min typ max units conditions 10 t os h2 ck losc1 to clko ? 75 200 ns (note 1) 11 t os h2 ck hosc1 to clko ? 75 200 ns (note 1) 12 t ck r clko rise time ? 35 100 ns (note 1) 13 t ck f clko fall time ? 35 100 ns (note 1) 14 t ck l2 io vclko to port out valid ? ? 0.5 t cy + 20 ns (note 1) 15 t io v2 ck h port in valid before clko 0.25 t cy + 25 ? ? ns (note 1) 16 t ck h2 io i port in hold after clko 0??ns (note 1) 17 t os h2 io vosc1 (q1 cycle) to port out valid ? 50 150 ns 18 t os h2 io iosc1 (q2 cycle) to port input invalid (i/o in hold time) pic18fxx20 100 ? ? ns 18a pic18lfxx20 200 ? ? ns v dd = 2.0v 19 t io v2 os h port input valid to osc1 (i/o in setup time) 0 ? ? ns 20 t io r port output rise time pic18fxx20 ? 10 25 ns 20a pic18lfxx20 ? ? 60 ns v dd = 2.0v 21 t io f port output fall time pic18fxx20 ? 10 25 ns 21a pic18lfxx20 ? ? 60 ns v dd = 2.0v 22? t inp int pin high or low time t cy ??ns 23? t rbp rb7:rb4 change int high or low time t cy ??ns 24? t rcp rc7:rc4 change int high or low time 20 ? ? ns ? these parameters are asynchronous events not related to any internal clock edges. note 1: measurements are taken in rc mode, where clko output is 4 x t osc . q1 q2 q3 q4 q1 q2 osc1 (1) ale oe address data from external 166 160 165 161 151 162 163 ad<15:0> 167 168 155 address address 150 a<19:16> address 169 ba0 ce 171 171a 164 operating conditions: 2.0v < v cc < 5.5v, -40c < t a < +125c unless otherwise stated. note 1: maximum speed of f osc is 25 mhz for external program memory read.
? 2004 microchip technology inc. ds39609b-page 325 pic18f6520/8520/6620/8620/6720/8720 table 26-9: clko and i/o timing requirements figure 26-10: program memo ry write timing diagram param no. symbol characteristics min typ max units 150 t ad v2 al l address out valid to ale (address setup time) 0.25 t cy ? 10 ? ? ns 151 t al l2 adl ale to address out invalid (address hold time) 5 ? ? ns 155 t al l2 oe lale to oe 10 0.125 t cy ?ns 160 t ad z2 oe l ad high-z to oe (bus release to oe )0??ns 161 t oe h2 ad doe to ad driven 0.125 t cy ? 5 ? ? ns 162 t ad v2 oe h ls data valid before oe (data setup time) 20 ? ? ns 163 t oe h2 adl oe to data in invalid (data hold time) 0 ? ? ns 164 t al h2 al l ale pulse width ? 0.25 t cy ?ns 165 t oe l2 oe hoe pulse width 0.5 t cy ? 5 0.5 t cy ?ns 166 t al h2 al hale to ale (cycle time) ? t cy ?ns 167 t acc address valid to data valid 0.75 t cy ? 25 ? ? ns 168 t oe oe to data valid ? 0.5 t cy ? 25 ns 169 t al l2 oe hale to oe 0.625 t cy ? 10 ? 0.625 t cy + 10 ns 171 t al h2 cs l chip enable active to ale ? ? 10 ns 171a t ub l2 oe h ad valid to chip enable active 0.25 t cy ? 20 ? ? ns q1 q2 q3 q4 q1 q2 osc1 (1) ale address data 156 150 151 153 ad<15:0> address wrh or wrl ub or lb 157 154 157a address a<19:16> address ba0 166 ce 171 171a operating conditions: 2.0v < v cc < 5.5v, -40c < t a < +125c unless otherwise stated. note 1: maximum speed of f osc is 25 mhz for external program memory read.
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 326 ? 2004 microchip technology inc. table 26-10: program memory write timing requirements figure 26-11: reset, watchdog timer, oscillator start-up timer and power-up timer timing param no. symbol characteristics min typ max units 150 t ad v2 al l address out valid to ale (address setup time) 0.25 t cy ? 10 ? ? ns 151 t al l2 adl ale to address out invalid (address hold time) 5 ? ? ns 153 t wr h2 adl wrn to data out invalid (data hold time) 5 ? ? ns 154 t wr l wrn pulse width 0.5 t cy ? 5 0.5 t cy ?ns 156 t ad v2 wr h data valid before wrn (data setup time) 0.5 t cy ? 10 ? ? ns 157 t bs v2 wr l byte select valid before wrn (byte select setup time) 0.25 t cy ??ns 157a t wr h2 bs iwrn to byte select invalid (byte select hold time) 0.125 t cy ? 5 ? ? ns 166 t al h2 al hale to ale (cycle time) ? t cy ?ns 171 t al h2 cs l chip enable active to ale ??10ns 171a t ub l2 oe h ad valid to chip enable active 0.25 t cy ? 20 ? ? ns v dd mclr internal por pwrt time-out osc time-out internal reset watchdog timer reset 33 32 30 31 34 i/o pins 34 note: refer to figure 26-6 for load conditions.
? 2004 microchip technology inc. ds39609b-page 327 pic18f6520/8520/6620/8620/6720/8720 figure 26-12: brown-out reset timing table 26-11: reset, watchdog timer, oscillator start-up timer, power-up timer and brown-out reset requirements figure 26-13: timer0 and timer1 external clock timings v dd bv dd 35 v bgap = 1.2v v irvst enable internal internal reference 36 reference voltage voltage stable param no. symbol characteristic min typ max units conditions 30 t mc lmclr pulse width (low) 2 ? ? s 31 t wdt watchdog timer time-out period (no postscaler) 71833ms 32 t ost oscillation start-up timer period 1024 t osc ? 1024 t osc ?t osc = osc1 period 33 t pwrt power-up timer period 28 72 132 ms 34 t ioz i/o high-impedance from mclr low or watchdog timer reset ?2? s 35 t bor brown-out reset pulse width 200 ? ? sv dd b vdd (see d005) 36 t ivrst time for internal reference voltage to become stable ?2050 s 37 t lvd low-voltage detect pulse width 200 ? ? sv dd v lvd note: refer to figure 26-6 for load conditions. 46 47 45 48 41 42 40 t0cki t1oso/t13cki tmr0 or tmr1
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 328 ? 2004 microchip technology inc. table 26-12: timer0 and timer1 external clock requirements figure 26-14: capture/compare/pwm timings (all ccp modules) param no. symbol characteristic min max units conditions 40 t t 0h t0cki high pulse width no prescaler 0.5 t cy + 20 ? ns with prescaler 10 ? ns 41 t t 0l t0cki low pulse width no prescaler 0.5 t cy + 20 ? ns with prescaler 10 ? ns 42 t t 0p t0cki period no prescaler t cy + 10 ? ns with prescaler greater of: 20 ns or t cy + 40 n ? ns n = prescale value (1, 2, 4,..., 256) 45 t t 1h t13cki high time synchronous, no prescaler 0.5 t cy + 20 ? ns synchronous, with prescaler pic18fxx20 10 ? ns pic18lfxx20 25 ? ns asynchronous pic18fxx20 30 ? ns pic18lfxx20 50 ? ns 46 t t 1l t13cki low time synchronous, no prescaler 0.5 t cy + 5 ? ns synchronous, with prescaler pic18fxx20 10 ? ns pic18lfxx20 25 ? ns asynchronous pic18fxx20 30 ? ns pic18lfxx20 tbd tbd ns 47 t t 1p t13cki input period synchronous greater of: 20 ns or t cy + 40 n ? ns n = prescale value (1, 2, 4, 8) asynchronous 60 ? ns f t 1 t13cki oscillator input frequency range dc 50 khz 48 t cke 2 tmr i delay from external t13cki clock edge to timer increment 2 t osc 7 t osc ? note: refer to figure 26-6 for load conditions. ccpx (capture mode) 50 51 52 ccpx 53 54 (compare or pwm mode)
? 2004 microchip technology inc. ds39609b-page 329 pic18f6520/8520/6620/8620/6720/8720 table 26-13: capture/compare/pwm requirements (all ccp modules) figure 26-15: parallel slave port timing (pic18f8x20) param no. symbol characteristic min max units conditions 50 t cc l ccpx input low time no prescaler 0.5 t cy + 20 ? ns with prescaler pic18fxx20 10 ? ns pic18lfxx20 20 ? ns 51 t cc h ccpx input high time no prescaler 0.5 t cy + 20 ? ns with prescaler pic18fxx20 10 ? ns pic18lfxx20 20 ? ns 52 t cc p ccpx input period 3 t cy + 40 n ? ns n = prescale value (1, 4 or 16) 53 t cc r ccpx output rise time pic18fxx20 ? 25 ns pic18lfxx20 ? 45 ns v dd = 2.0v 54 t cc f ccpx output fall time pic18fxx20 ? 25 ns pic18lfxx20 ? 45 ns v dd = 2.0v note: refer to figure 26-6 for load conditions. re2/cs re0/rd re1/wr rd7:rd0 62 63 64 65
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 330 ? 2004 microchip technology inc. table 26-14: parallel slave port requirements (pic18f8x20) figure 26-16: example spi ma ster mode timing (cke = 0 ) param no. symbol characteristic min max units conditions 62 t dt v2 wr h data in valid before wr or cs (setup time) 20 25 ? ? ns ns extended temp. range 63 t wr h2 dt iwr or cs to data?in invalid (hold time) pic18fxx20 20 ? ns pic18lfxx20 35 ? ns v dd = 2.0v 64 t rd l2 dt vrd and cs to data?out valid ? ? 80 90 ns ns extended temp. range 65 t rd h2 dt ird or cs to data?out invalid 10 30 ns 66 t ibf inh inhibit of the ibf flag bit being cleared from wr or cs ?3 t cy ss sck (ckp = 0 ) sck (ckp = 1 ) sdo sdi 70 71 72 73 74 75, 76 78 79 80 79 78 msb lsb bit 6 - - - - - -1 msb in lsb in bit 6 - - - -1 note: refer to figure 26-6 for load conditions.
? 2004 microchip technology inc. ds39609b-page 331 pic18f6520/8520/6620/8620/6720/8720 table 26-15: example spi mode requirements (master mode, cke = 0 ) figure 26-17: example spi ma ster mode timing (cke = 1 ) param no. symbol characteristic min max units conditions 70 t ss l2 sc h, t ss l2 sc l ss to sck or sck input t cy ?ns 71 t sc h sck input high time (slave mode) continuous 1.25 t cy + 30 ? ns 71a single byte 40 ? ns (note 1) 72 t sc l sck input low time (slave mode) continuous 1.25 t cy + 30 ? ns 72a single byte 40 ? ns (note 1) 73 t di v2 sc h, t di v2 sc l setup time of sdi data input to sck edge 100 ? ns 73a t b 2 b last clock edge of byte 1 to the 1st clock edge of byte 2 1.5 t cy + 40 ? ns (note 2) 74 t sc h2 di l, t sc l2 di l hold time of sdi data input to sck edge 100 ? ns 75 t do r sdo data output rise time pic18fxx20 ? 25 ns pic18lfxx20 ? 45 ns v dd = 2.0v 76 t do f sdo data output fall time ? 25 ns 78 t sc r sck output rise time (master mode) pic18fxx20 ? 25 ns pic18lfxx20 ? 45 ns v dd = 2.0v 79 t sc f sck output fall time (master mode) ? 25 ns 80 t sc h2 do v, t sc l2 do v sdo data output valid after sck edge pic18fxx20 ? 50 ns pic18lfxx20 ? 100 ns v dd = 2.0v note 1: requires the use of parameter #73a. 2: only if parameter #71a and #72a are used. ss sck (ckp = 0 ) sck (ckp = 1 ) sdo sdi 81 71 72 74 75, 76 78 80 msb 79 73 msb in bit 6 - - - - - -1 lsb in bit 6 - - - -1 lsb note: refer to figure 26-6 for load conditions.
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 332 ? 2004 microchip technology inc. table 26-16: example spi mode requirements (master mode, cke = 1 ) figure 26-18: example spi slave mode timing (cke = 0 ) param no. symbol characteristic min max units conditions 71 t sc h sck input high time (slave mode) continuous 1.25 t cy + 30 ? ns 71a single byte 40 ? ns (note 1) 72 t sc l sck input low time (slave mode) continuous 1.25 t cy + 30 ? ns 72a single byte 40 ? ns (note 1) 73 t di v2 sc h, t di v2 sc l setup time of sdi data input to sck edge 100 ? ns 73a t b 2 b last clock edge of byte 1 to the 1st clock edge of byte 2 1.5 t cy + 40 ? ns (note 2) 74 t sc h2 di l, t sc l2 di l hold time of sdi data input to sck edge 100 ? ns 75 t do r sdo data output rise time pic18fxx20 ? 25 ns pic18lfxx20 ? 45 ns v dd = 2.0v 76 t do f sdo data output fall time ? 25 ns 78 t sc r sck output rise time (master mode) pic18fxx20 ? 25 ns pic18lfxx20 ? 45 ns v dd = 2.0v 79 t sc f sck output fall time (master mode) ? 25 ns 80 t sc h2 do v, t sc l2 do v sdo data output valid after sck edge pic18fxx20 ? 50 ns pic18lfxx20 ? 100 ns v dd = 2.0v 81 t do v2 sc h, t do v2 sc l sdo data output setup to sck edge t cy ?ns note 1: requires the use of parameter #73a. 2: only if parameter #71a and #72a are used. ss sck (ckp = 0 ) sck (ckp = 1 ) sdo sdi 70 71 72 73 74 75, 76 77 78 79 80 79 78 sdi msb lsb bit 6 - - - - - -1 msb in bit 6 - - - -1 lsb in 83 note: refer to figure 26-6 for load conditions.
? 2004 microchip technology inc. ds39609b-page 333 pic18f6520/8520/6620/8620/6720/8720 table 26-17: example spi mode requirements (slave mode timing, cke = 0 ) figure 26-19: example spi slave mode timing (cke = 1 ) param no. symbol characteristic min max units conditions 70 t ss l2 sc h, t ss l2 sc l ss to sck or sck input t cy ?ns 71 t sc h sck input high time (slave mode) continuous 1.25 t cy + 30 ? ns 71a single byte 40 ? ns (note 1) 72 t sc l sck input low time (slave mode) continuous 1.25 t cy + 30 ? ns 72a single byte 40 ? ns (note 1) 73 t di v2 sc h, t di v2 sc l setup time of sdi data input to sck edge 100 ? ns 73a t b 2 b last clock edge of byte 1 to the first clock edge of byte 2 1.5 t cy + 40 ? ns (note 2) 74 t sc h2 di l, t sc l2 di l hold time of sdi data input to sck edge 100 ? ns 75 t do r sdo data output rise time pic18fxx20 ? 25 ns pic18lfxx20 ? 45 ns v dd = 2.0v 76 t do f sdo data output fall time ? 25 ns 77 t ss h2 do zss to sdo output high-impedance 10 50 ns 78 t sc r sck output rise time (master mode) pic18fxx20 ? 25 ns pic18lfxx20 ? 45 ns v dd = 2.0v 79 t sc f sck output fall time (master mode) ? 25 ns 80 t sc h2 do v, t sc l2 do v sdo data output valid after sck edge pic18fxx20 ? 50 ns pic18lfxx20 ? 100 ns v dd = 2.0v 83 t sc h2 ss h, t sc l2 ss h ss after sck edge 1.5 t cy + 40 ? ns note 1: requires the use of parameter #73a. 2: only if parameter #71a and #72a are used. ss sck (ckp = 0 ) sck (ckp = 1 ) sdo sdi 70 71 72 82 sdi 74 75, 76 msb bit 6 - - - - - -1 lsb 77 msb in bit 6 - - - -1 lsb in 80 83 note: refer to figure 26-6 for load conditions.
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 334 ? 2004 microchip technology inc. table 26-18: example spi slave mode requirements (cke = 1 ) figure 26-20: i 2 c bus start/stop bits timing param no. symbol characteristic min max units conditions 70 t ss l2 sc h, t ss l2 sc l ss to sck or sck input t cy ?ns 71 t sc h sck input high time (slave mode) continuous 1.25 t cy + 30 ? ns 71a single byte 40 ? ns (note 1) 72 t sc l sck input low time (slave mode) continuous 1.25 t cy + 30 ? ns 72a single byte 40 ? ns (note 1) 73a t b 2 b last clock edge of byte 1 to the first clock edge of byte 2 1.5 t cy + 40 ? ns (note 2) 74 t sc h2 di l, t sc l2 di l hold time of sdi data input to sck edge 100 ? ns 75 t do r sdo data output rise time pic18fxx20 ? 25 ns pic18lfxx20 ? 45 ns v dd = 2.0v 76 t do f sdo data output fall time ? 25 ns 77 t ss h2 do zss to sdo output high-impedance 10 50 ns 78 t sc r sck output rise time (master mode) pic18fxx20 ? 25 ns pic18lfxx20 ? 45 ns v dd = 2.0v 79 t sc f sck output fall time (master mode) ? 25 ns 80 t sc h2 do v, t sc l2 do v sdo data output valid after sck edge pic18fxx20 ? 50 ns pic18lfxx20 ? 100 ns v dd = 2.0v 82 t ss l2 do v sdo data output valid after ss edge pic18fxx20 ? 50 ns pic18lfxx20 ? 100 ns v dd = 2.0v 83 t sc h2 ss h, t sc l2 ss h ss after sck edge 1.5 t cy + 40 ? ns note 1: requires the use of parameter #73a. 2: only if parameter #71a and #72a are used. note: refer to figure 26-6 for load conditions. 91 92 93 scl sda start condition stop condition 90
? 2004 microchip technology inc. ds39609b-page 335 pic18f6520/8520/6620/8620/6720/8720 table 26-19: i 2 c bus start/stop bits requirements (slave mode) figure 26-21: i 2 c bus data timing param no. symbol characteristic min max units conditions 90 t su : sta start condition 100 khz mode 4700 ? ns only relevant for repeated start condition setup time 400 khz mode 600 ? 91 t hd : sta start condition 100 khz mode 4000 ? ns after this period, the first clock pulse is generated hold time 400 khz mode 600 ? 92 t su : sto stop condition 100 khz mode 4700 ? ns setup time 400 khz mode 600 ? 93 t hd : sto stop condition 100 khz mode 4000 ? ns hold time 400 khz mode 600 ? note: refer to figure 26-6 for load conditions. 90 91 92 100 101 103 106 107 109 109 110 102 scl sda in sda out
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 336 ? 2004 microchip technology inc. table 26-20: i 2 c bus data requirements (slave mode) param no. symbol characteristic min max units conditions 100 t high clock high time 100 khz mode 4.0 ? s 400 khz mode 0.6 ? s ssp module 1.5 t cy ? 101 t low clock low time 100 khz mode 4.7 ? s pic18fxx20 must operate at a minimum of 1.5 mhz 400 khz mode 1.3 ? s pic18fxx20 must operate at a minimum of 10 mhz ssp module 1.5 t cy ? 102 t r sda and scl rise time 100 khz mode ? 1000 ns 400 khz mode 20 + 0.1 c b 300 ns c b is specified to be from 10 to 400 pf 103 t f sda and scl fall time 100 khz mode ? 300 ns 400 khz mode 20 + 0.1 c b 300 ns c b is specified to be from 10 to 400 pf 90 t su : sta start condition setup time 100 khz mode 4.7 ? s only relevant for repeated start condition 400 khz mode 0.6 ? s 91 t hd : sta start condition hold time 100 khz mode 4.0 ? s after this period, the first clock pulse is generated 400 khz mode 0.6 ? s 106 t hd : dat data input hold time 100 khz mode 0 ? ns 400 khz mode 0 0.9 s 107 t su : dat data input setup time 100 khz mode 250 ? ns (note 2) 400 khz mode 100 ? ns 92 t su : sto stop condition setup time 100 khz mode 4.7 ? s 400 khz mode 0.6 ? s 109 t aa output valid from clock 100 khz mode ? 3500 ns (note 1) 400 khz mode ? ? ns 110 t buf bus free time 100 khz mode 4.7 ? s time the bus must be free before a new transmission can start 400 khz mode 1.3 ? s d102 c b bus capacitive loading ? 400 pf note 1: as a transmitter, the device must provide this internal minimum delay time to bridge the undefined region (min. 300 ns) of the falling edge of scl to avoid unintended generation of start or stop conditions. 2: a fast mode i 2 c bus device can be used in a standard mode i 2 c bus system but the requirement, t su : dat 250 ns, must then be met. this will automatically be the case if the device does not stretch the low period of the scl signal. if such a device does stretch the low period of the scl signal, it must output the next data bit to the sda line, t r max. + t su : dat = 1000 + 250 = 1250 ns (according to the standard mode i 2 c bus specification), before the scl line is released.
? 2004 microchip technology inc. ds39609b-page 337 pic18f6520/8520/6620/8620/6720/8720 figure 26-22: master ssp i 2 c bus start/stop bits timing waveforms table 26-21: master ssp i 2 c bus start/stop bits requirements figure 26-23: master ssp i 2 c bus data timing note: refer to figure 26-6 for load conditions. 91 93 scl sda start condition stop condition 90 92 param no. symbol characteristic min max units conditions 90 t su : sta start condition setup time 100 khz mode 2(t osc )(brg + 1) ? ns only relevant for repeated start condition 400 khz mode 2(t osc )(brg + 1) ? 1 mhz mode (1) 2(t osc )(brg + 1) ? 91 t hd : sta start condition hold time 100 khz mode 2(t osc )(brg + 1) ? ns after this period, the first clock pulse is generated 400 khz mode 2(t osc )(brg + 1) ? 1 mhz mode (1) 2(t osc )(brg + 1) ? 92 t su : sto stop condition setup time 100 khz mode 2(t osc )(brg + 1) ? ns 400 khz mode 2(t osc )(brg + 1) ? 1 mhz mode (1) 2(t osc )(brg + 1) ? 93 t hd : sto stop condition hold time 100 khz mode 2(t osc )(brg + 1) ? ns 400 khz mode 2(t osc )(brg + 1) ? 1 mhz mode (1) 2(t osc )(brg + 1) ? note 1: maximum pin capacitance = 10 pf for all i 2 c pins. note: refer to figure 26-6 for load conditions. 90 91 92 100 101 103 106 107 109 109 110 102 scl sda in sda out
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 338 ? 2004 microchip technology inc. table 26-22: master ssp i 2 c bus data requirements param no. symbol characteristic min max units conditions 100 t high clock high time 100 khz mode 2(t osc )(brg + 1) ? ms 400 khz mode 2(t osc )(brg + 1) ? ms 1 mhz mode (1) 2(t osc )(brg + 1) ? ms 101 t low clock low time 100 khz mode 2(t osc )(brg + 1) ? ms 400 khz mode 2(t osc )(brg + 1) ? ms 1 mhz mode (1) 2(t osc )(brg + 1) ? ms 102 t r sda and scl rise time 100 khz mode ? 1000 ns c b is specified to be from 10 to 400 pf 400 khz mode 20 + 0.1 c b 300 ns 1 mhz mode (1) ? 300 ns 103 t f sda and scl fall time 100 khz mode ? 300 ns c b is specified to be from 10 to 400 pf 400 khz mode 20 + 0.1 c b 300 ns 1 mhz mode (1) ? 100 ns 90 t su : sta start condition setup time 100 khz mode 2(t osc )(brg + 1) ? ms only relevant for repeated start condition 400 khz mode 2(t osc )(brg + 1) ? ms 1 mhz mode (1) 2(t osc )(brg + 1) ? ms 91 t hd : sta start condition hold time 100 khz mode 2(t osc )(brg + 1) ? ms after this period, the first clock pulse is generated 400 khz mode 2(t osc )(brg + 1) ? ms 1 mhz mode (1) 2(t osc )(brg + 1) ? ms 106 t hd : dat data input hold time 100 khz mode 0 ? ns 400 khz mode 0 0.9 ms 1 mhz mode (1) tbd ? ns 107 t su : dat data input setup time 100 khz mode 250 ? ns (note 2) 400 khz mode 100 ? ns 1 mhz mode (1) tbd ? ns 92 t su : sto stop condition setup time 100 khz mode 2(t osc )(brg + 1) ? ms 400 khz mode 2(t osc )(brg + 1) ? ms 1 mhz mode (1) 2(t osc )(brg + 1) ? ms 109 t aa output valid from clock 100 khz mode ? 3500 ns 400 khz mode ? 1000 ns 1 mhz mode (1) ??ns 110 t buf bus free time 100 khz mode 4.7 ? ms time the bus must be free before a new transmission can start 400 khz mode 1.3 ? ms 1 mhz mode (1) tbd ? ms d102 c b bus capacitive loading ? 400 pf note 1: maximum pin capacitance = 10 pf for all i 2 c pins. 2: a fast mode i 2 c bus device can be used in a standard mode i 2 c bus system, but parameter #107 250 ns, must then be met. this will automatically be the case if the device does not stretch the low period of the scl signal. if such a device does stretch the low period of the scl signal, it must output the next data bit to the sda line, parameter #102 + parameter #107 = 1000 + 250 = 1250 ns (for 100 khz mode), before the scl line is released.
? 2004 microchip technology inc. ds39609b-page 339 pic18f6520/8520/6620/8620/6720/8720 figure 26-24: usart synchronous transmission (master/slave) timing table 26-23: usart synchronous transmission requirements figure 26-25: usart synchronous receive (master/slave) timing table 26-24: usart synchronous receive requirements 121 121 120 122 rc6/tx1/ck1 rc7/rx1/dt1 pin pin note: refer to figure 26-6 for load conditions. param no. symbol characteristic min max units conditions 120 t ck h2 dt v sync xmit (master & slave) clock high to data out valid pic18fxx20 ? 40 ns pic18lfxx20 ? 100 ns v dd = 2.0v 121 t ckrf clock out rise time and fall time (master mode) pic18fxx20 ? 20 ns pic18lfxx20 ? 50 ns v dd = 2.0v 122 t dtrf data out rise time and fall time pic18fxx20 ? 20 ns pic18lfxx20 ? 50 ns v dd = 2.0v 125 126 rc6/tx1/ck1 rc7/rx1/dt1 pin pin note: refer to figure 26-6 for load conditions. param no. symbol characteristic min max units conditions 125 t dt v2 ckl sync rcv (master & slave) data hold before ck (dt hold time) 10 ? ns 126 t ck l2 dtl data hold after ck (dt hold time) 15 ? ns
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 340 ? 2004 microchip technology inc. table 26-25: a/d converter characteristics: pic18fxx20 (industrial, extended) pic18lfxx20 (industrial) figure 26-26: a/d conversion timing param no. symbol characteristic min typ max units conditions a01 n r resolution ? ? 10 bit a03 e il integral linearity error ? ? <1 lsb v ref = v dd = 5.0v a04 e dl differential linearity error ? ? <1 lsb v ref = v dd = 5.0v a05 e g gain error ? ? <1 lsb v ref = v dd = 5.0v a06 e off offset error ? ? <1.5 lsb v ref = v dd = 5.0v a10 ? monotonicity guaranteed (2) ?v ss v ain v ref a20 a20a v ref reference voltage (v refh ? v refl ) 1.8v 3v ? ? ? ? v v v dd < 3.0v v dd 3.0v a21 v refh reference voltage high av ss ?av dd + 0.3v v a22 v refl reference voltage low av ss ? 0.3v (5) ?v refh v a25 v ain analog input voltage av ss ? 0.3v (5) ?av dd + 0.3v (5) vv dd 2.5v (note 3) a30 z ain recommended impedance of analog voltage source ??2.5k ? (note 4) a50 i ref v ref input current (note 1) ? ? ? ? 5 150 a a during v ain acquisition. during a/d conversion cycle. note 1: vss v ain v ref 2: the a/d conversion result never decreases with an increase in the input voltage and has no missing codes. 3: for v dd < 2.5v, v ain should be limited to <.5 v dd . 4: maximum allowed impedance for analog voltage source is 10 k ? . this requires higher acquisition times. 5: iv dd ? av dd i must be <3.0v and iav ss ? v ss i must be <0.3v. 131 130 132 bsf adcon0, go q4 a/d clk a/d data adres adif go sample old_data sampling stopped done new_data (note 2) 987 21 0 note 1: if the a/d clock source is selected as rc, a time of t cy is added before the a/d clock starts. this allows the sleep instruction to be executed. 2: this is a minimal rc delay (typically 100 ns), which also disconnects the holding capacitor from the analog input. . . . . . . t cy
? 2004 microchip technology inc. ds39609b-page 341 pic18f6520/8520/6620/8620/6720/8720 table 26-26: a/d conversion requirements param no. symbol characteristic min max units conditions 130 t ad a/d clock period pic18fxx20 1.6 20 (5) st osc based, v ref 3.0v pic18lfxx20 3.0 20 (5) st osc based, v ref full range pic18fxx20 2.0 6.0 s a/d rc mode pic18lfxx20 3.0 9.0 s a/d rc mode 131 t cnv conversion time (not including acquisition time) (note 1) 11 12 t ad 132 t acq acquisition time (note 3) 15 10 ? ? s s -40 c te mp +125 c 0 c te m p +125 c 135 t swc switching time from convert sample ? (note 4) 136 t amp amplifier settling time (note 2) 1? s this may be used if the ?new? input voltage has not changed by more than 1 lsb (i.e., 5 mv @ 5.12v) from the last sampled voltage (as stated on c hold ). note 1: adres register may be read on the following t cy cycle. 2: see section 19.0 ?10-bit analog-to-digital converter (a/d) module? for minimum conditions when input voltage has changed more than 1 lsb. 3: the time for the holding capacitor to acquire the ?new? input voltage when the voltage changes full scale after the conversion (av dd to av ss , or av ss to av dd ). the source impedance ( r s ) on the input channels is 50 ? . 4: on the next q4 cycle of the device clock. 5: the time of the a/d clock period is dependent on the device frequency and the t ad clock divider.
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 342 ? 2004 microchip technology inc. notes:
? 2004 microchip technology inc. ds39609b-page 343 pic18f6520/8520/6620/8620/6720/8720 27.0 dc and ac characteristics graphs and tables ?typical? represents the mean of the distribution at 25 c. ?maximum? or ?minimum? represents (mean + 3 ) or (mean ?? 3 ) respectively, where is a standard deviation, over the whole temperature range. figure 27-1: typical i dd vs. f osc over v dd (hs mode) figure 27-2: maximum i dd vs. f osc over v dd (hs mode) industrial note: the graphs and tables provided following this note are a statistical summary based on a limited number of samples and are provided for informational purposes only. the performance characteristics listed herein are not tested or guaranteed. in some graphs or tables, the data presented may be outside the specified operating range (e.g., outside specified power supply range) and therefore, outside the warranted range. 0 2 4 6 8 10 12 14 16 18 20 4 6 8 101214161820222426 f osc (mhz) i dd (ma) 2.0v 2.5v 3.0v 3.5v 4.0v 4.5v 5.0v 5.5v typical: statistical mean @ 25c maximum: mean + 3 (-40c to +125c) minimum: mean ? 3 (-40c to +125c) 0 2 4 6 8 10 12 14 16 18 20 4 6 8 101214161820222426 f osc (mhz) i dd (ma) 2.0v 2.5v 3.0v 3.5v 4.0v 4.5v 5.0v 5.5v typical: statistical mean @ 25c maximum: mean + 3 (-40c to +85c) minimum: mean ? 3 (-40c to +85c)
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 344 ? 2004 microchip technology inc. figure 27-3: maximum i dd vs. f osc over v dd (hs mode) extended figure 27-4: typical i dd vs. f osc over v dd (hs/pll mode) 0 2 4 6 8 10 12 14 16 18 20 4 6 8 10 12 14 16 18 20 22 24 26 f osc (m hz ) i dd (ma) 2.0v 2.5v 3.0v 3.5v 4.0v 4.5v 5.0v 5.5v typical: statistical mean @ 25c maximum: mean + 3 (-40c to +125c) minimum: mean ? 3 (-40c to +125c) 0 2 4 6 8 10 12 14 16 18 20 4 6 8 101214161820222426 f osc (mhz) i dd (ma) 2.0v 2.5v 3.0v 3.5v 4.0v 4.5v 5.0v 5.5v typical: statistical mean @ 25c maximum: mean + 3 (-40c to +125c) minimum: mean ? 3 (-40c to +125c)
? 2004 microchip technology inc. ds39609b-page 345 pic18f6520/8520/6620/8620/6720/8720 figure 27-5: maximum i dd vs. f osc over v dd (hs/pll mode) industrial figure 27-6: maximum i dd vs. f osc over v dd (hs/pll mode) extended 0 2 4 6 8 10 12 14 16 18 20 4 6 8 101214161820222426 f osc (mhz) i dd (ma) 2.0v 2.5v 3.0v 3.5v 4.0v 4.5v 5.0v 5.5v typical: statistical mean @ 25c maximum: mean + 3 (-40c to +85c) minimum: mean ? 3 (-40c to +85c) 0 2 4 6 8 10 12 14 16 18 20 4.0 6.0 8.0 10.0 12.0 14.0 16.0 18.0 20.0 22.0 24.0 26.0 f osc (mhz) i dd (ma) 2.0v 2.5v 3.0v 3.5v 4.0v 4.5v 5.0v 5.5v typical: statistical mean @ 25c maximum: mean + 3 (-40c to +125c) minimum: mean ? 3 (-40c to +125c)
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 346 ? 2004 microchip technology inc. figure 27-7: typical i dd vs. f osc over v dd (xt mode) figure 27-8: maximum i dd vs. f osc over v dd (xt mode) industrial 0.0 0.5 1.0 1.5 2.0 2.5 3.0 0.00.51.01.52.02.53.03.54.0 f osc (mhz) i dd (ua) 4.0v 4.5v 3.0v 3.5v 2.0v 2.5v 5.0v 5.5v typical: statistical mean @ 25c maximum: mean + 3 (-40c to +125c) minimum: mean ? 3 (-40c to +125c) 0.0 0.5 1.0 1.5 2.0 2.5 3.0 0.00.51.01.52.02.53.03.54.0 f osc (mhz) i dd (ua) 4.0v 4.5v 3.0v 3.5v 2.0v 2.5v 5.0v 5.5v typical: statistical mean @ 25c maximum: mean + 3 (-40c to +85c) minimum: mean ? 3 (-40c to +85c)
? 2004 microchip technology inc. ds39609b-page 347 pic18f6520/8520/6620/8620/6720/8720 figure 27-9: typical i dd vs. f osc over v dd (lp mode) figure 27-10: maximum i dd vs. f osc over v dd (lp mode) industrial 0 10 20 30 40 50 60 70 80 90 100 0 102030405060708090100 f osc (khz) i dd (ua) 2.0v 2.5v 3.0v 3.5v 4.0v 4.5v 5.0v 5.5v typical: statistical mean @ 25c maximum: mean + 3 (-40c to +125c) minimum: mean ? 3 (-40c to +125c) 0 20 40 60 80 100 120 0 102030405060708090100 f osc (khz) i dd (ua) 2.0v 2.5v 3.0v 3.5v 4.0v 4.5v 5.0v 5.5v typical: statistical mean @ 25c maximum: mean + 3 (-40c to +85c) minimum: mean ? 3 (-40c to +85c)
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 348 ? 2004 microchip technology inc. figure 27-11: maximum i dd vs. f osc over v dd (lp mode) extended figure 27-12: typical i dd vs. f osc over v dd (ec mode) 0 50 100 150 200 250 300 0 102030405060708090100 f osc (khz) i dd (ua) 2.0v 2.5v 3.0v 3.5v 4.0v 4.5v 5.0v 5.5v typical: statistical mean @ 25c maximum: mean + 3 (-40c to +125c) minimum: mean ? 3 (-40c to +125c) 0 2 4 6 8 10 12 14 16 18 4 6 8 101214161820222426 f osc (mhz) i dd (ma) 4.0v 4.5v 3.0v 3.5v 2.0v 2.5v 5.0v 5.5v typical: statistical mean @ 25c maximum: mean + 3 (-40c to +125c) minimum: mean ? 3 (-40c to +125c)
? 2004 microchip technology inc. ds39609b-page 349 pic18f6520/8520/6620/8620/6720/8720 figure 27-13: maximum i dd vs. f osc over v dd (ec mode) figure 27-14: maximum i pd vs. v dd over temperature 0 2 4 6 8 10 12 14 16 18 4 6 8 101214161820222426 f osc (mhz) i dd (ma) 5.0v 5.5v 4.0v 4.5v 3.0v 3.5v 2.0v 2.5v typical: statistical mean @ 25c maximum: mean + 3 (-40c to +125c) minimum: mean ? 3 (-40c to +125c) 0.01 0.1 1 10 100 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 v dd (v) i pd (ua) typ (25c) max (-40c:+85c) max (-40c:+125c) typical: statistical mean @ 25c maximum: mean + 3 (-40c to +125c) minimum: mean ? 3 (-40c to +125c)
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 350 ? 2004 microchip technology inc. figure 27-15: typical and maximum i pd vs. v dd over temperature (timer1 as main oscillator, 32.768 khz, c1 and c2 = 47 pf) figure 27-16: typical and maximum ? i wdt vs. v dd over temperature (wdt enabled) 1 10 100 1000 2.02.53.03.54.04.55.05.5 v dd (v) i pd (ua) typ (25c) max (-40c:+85c) max (-40c:+125c) typical: statistical mean @ 25c maximum: mean + 3 (-40c to +125c) minimum: mean ? 3 (-40c to +125c) 0.1 1 10 100 1000 2.02.53.03.54.04.55.05.5 v dd (v) i pd (ua) typ (25c) max (-40c:+85c) max (-40c:+125c) typical: statistical mean @ 25c maximum: mean + 3 (-40c to +125c) minimum: mean ? 3 (-40c to +125c)
? 2004 microchip technology inc. ds39609b-page 351 pic18f6520/8520/6620/8620/6720/8720 figure 27-17: typical i dd vs. f osc over v dd (ec mode) figure 27-18: maximum i dd vs. f osc over v dd (ec mode) 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 0.55 0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 0.18 0.20 f osc (mhz) i dd (ma) 4.0v 4.5v 3.0v 3.5v 2.0v 2.5v 5.0v 5.5v typical: statistical mean @ 25c maximum: mean + 3 (-40c to +125c) minimum: mean ? 3 (-40c to +125c) 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 0.55 0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 0.18 0.20 f osc (mhz) i dd (ma) 4.0v 4.5v 3.0v 3.5v 2.0v 2.5v 5.0v 5.5v typical: statistical mean @ 25c maximum: mean + 3 (-40c to +125c) minimum: mean ? 3 (-40c to +125c)
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 352 ? 2004 microchip technology inc. figure 27-19: typical i dd vs. f osc over v dd (ec mode) (pic18f8520 devices only) figure 27-20: maximum i dd vs. f osc over v dd (ec mode) industrial (pic18f8520 devices only) 0 5 10 15 20 25 30 4 8 12 16 20 24 28 32 36 40 f osc (mhz) i dd (ma) 4.0v 4.5v 3.0v 3.5v 2.0v 2.5v 5.0v 5.5v 4.2v typical: statistical mean @ 25c maximum: mean + 3 (-40c to +125c) minimum: mean ? 3 (-40c to +125c) 0 5 10 15 20 25 30 4 8 12 16 20 24 28 32 36 40 f osc (mhz) i dd (ma) 5.0v 5.5v 4.2v 4.5v 3.0v 3.5v 2.0v 2.5v 4.0v typical: statistical mean @ 25c maximum: mean + 3 (-40c to +85c) minimum: mean ? 3 (-40c to +85c)
? 2004 microchip technology inc. ds39609b-page 353 pic18f6520/8520/6620/8620/6720/8720 figure 27-21: maximum i dd vs. f osc over v dd (ec mode) extended (pic18f8520 devices only) figure 27-22: typical i dd vs. f osc over v dd (hs/pll mode) (pic18f8520 devices only) 0 2 4 6 8 10 12 14 16 18 20 4 6 8 101214161820222426 f osc (mhz) i dd (ma) 5.0v 5.5v 4.2v 4.5v 3.0v 3.5v 2.0v 2.5v 4.0v typical: statistical mean @ 25c maximum: mean + 3 (-40c to +125c) minimum: mean ? 3 (-40c to +125c) 0 3 6 9 12 15 18 21 24 27 30 4 8 12 16 20 24 28 32 36 40 f osc (mhz) i dd (ma) 2.0v 2.5v 3.0v 3.5v 4.0v 4.5v 5.0v 5.5v 4.2v typical: statistical mean @ 25c maximum: mean + 3 (-40c to +125c) minimum: mean ? 3 (-40c to +125c)
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 354 ? 2004 microchip technology inc. figure 27-23: maximum i dd vs. f osc over v dd (hs/pll mode) industrial (pic18f8520 devices only) figure 27-24: maximum i dd vs. f osc over v dd (hs/pll mode) extended (pic18f8520 devices only) 0 3 6 9 12 15 18 21 24 27 30 4 8 12 16 20 24 28 32 36 40 f osc (mhz) i dd (ma) 2.0v 2.5v 3.0v 3.5v 4.0v 4.5v 5.0v 5.5v 4.2v typical: statistical mean @ 25c maximum: mean + 3 (-40c to +85c) minimum: mean ? 3 (-40c to +85c) 0 2 4 6 8 10 12 14 16 18 20 4 6 8 101214161820222426 f osc (mhz) i dd (ma) 2.0v 2.5v 3.0v 3.5v 4.0v 4.5v 5.0v 5.5v 4.2v typical: statistical mean @ 25c maximum: mean + 3 (-40c to +125c) minimum: mean ? 3 (-40c to +125c)
? 2004 microchip technology inc. ds39609b-page 355 pic18f6520/8520/6620/8620/6720/8720 figure 27-25: a/d nonlinearity vs. v refh (v dd = v refh , -40 c to +125 c) figure 27-26: a/d nonlinearity vs. v refh (v dd = 5v, -40 c to +125 c) 0 0.5 1 1.5 2 2.5 3 3.5 4 22.533.544.555.5 v dd and v refh (v) differential or integral nonlinearity (lsb) -40c 25c 85c 125c -40c +25c +85c +125c 0 0.5 1 1.5 2 2.5 3 22.533.544.555.5 v refh (v) differential or integral nonlinearilty (lsb) max (-40c to 125c) typ (25c) typ (+25c) max (-40c to +125c)
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 356 ? 2004 microchip technology inc. notes:
? 2004 microchip technology inc. ds39609b-page 357 pic18f6520/8520/6620/8620/6720/8720 28.0 packaging information 28.1 package marking information 64-lead tqfp xxxxxxxxxx xxxxxxxxxx xxxxxxxxxx yywwnnn example pic18f6620 -i/pt 0410017 80-lead tqfp xxxxxxxxxxxx xxxxxxxxxxxx yywwnnn example pic18f8720 -e/pt 0410017 legend: xx...x customer specific information* y year code (last digit of calendar year) yy year code (last 2 digits of calendar year) ww week code (week of january 1 is week ?01?) nnn alphanumeric traceability code note : in the event the full microchip part number cannot be marked on one line, it will be carried over to the next line thus limiting the number of available characters for customer specific information. * standard picmicro device marking consists of microchip part number, year code, week code, and traceability code. for picmicro device marking beyond this, certain price adders apply. please check with your microchip sales office. for qtp devices, any special marking adders are included in qtp price.
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 358 ? 2004 microchip technology inc. 28.2 package details the following sections give the technical details of the packages. 64-lead plastic thin quad flatpack (pt) 10x10x1 mm body, 1.0/0.10 mm lead form (tqfp) * controlling parameter notes: dimensions d1 and e1 do not include mold flash or protrusions. mold flash or protrusions shall not exceed .010? (0.254mm) per side. jedec equivalent: ms-026 drawing no. c04-085 15 10 5 15 10 5 mold draft angle bottom 15 10 5 15 10 5 mold draft angle top 0.27 0.22 0.17 .011 .009 .007 b lead width 0.23 0.18 0.13 .009 .007 .005 c lead thickness 16 16 n1 pins per side 10.10 10.00 9.90 .398 .394 .390 d1 molded package length 10.10 10.00 9.90 .398 .394 .390 e1 molded package width 12.25 12.00 11.75 .482 .472 .463 d overall length 12.25 12.00 11.75 .482 .472 .463 e overall width 7 3.5 0 7 3.5 0 foot angle 0.75 0.60 0.45 .030 .024 .018 l foot length 0.25 0.15 0.05 .010 .006 .002 a1 standoff 1.05 1.00 0.95 .041 .039 .037 a2 molded package thickness 1.20 1.10 1.00 .047 .043 .039 a overall height 0.50 .020 p pitch 64 64 n number of pins max nom min max nom min dimension limits millimeters* inches units c 2 1 n d d1 b p #leads=n1 e1 e a2 a1 a l ch x 45 (f) footprint (reference) (f) .039 1.00 pin 1 corner chamfer ch .025 .035 .045 0.64 0.89 1.14 significant characteristic
? 2004 microchip technology inc. ds39609b-page 359 pic18f6520/8520/6620/8620/6720/8720 80-lead plastic thin quad flatpack (pt) 12x12x1 mm body, 1.0/0.10 mm lead form (tqfp) * controlling parameter notes: dimensions d1 and e1 do not include mold flash or protrusions. mold flash or protrusions shall not exceed .010? (0.254mm) per side. jedec equivalent: ms-026 drawing no. c04-092 1.10 1.00 .043 .039 1.14 0.89 0.64 .045 .035 .025 ch pin 1 corner chamfer 1.00 .039 (f) footprint (reference) (f) e e1 #leads=n1 p b d1 d n 1 2 c l a a1 a2 units inches millimeters* dimension limits min nom max min nom max number of pins n 80 80 pitch p .020 0.50 overall height a .047 1.20 molded package thickness a2 .037 .039 .041 0.95 1.00 1.05 standoff a1 .002 .004 .006 0.05 0.10 0.15 foot length l .018 .024 .030 0.45 0.60 0.75 foot angle 03.5 7 03.5 7 overall width e .541 .551 .561 13.75 14.00 14.25 overall length d .541 .551 .561 13.75 14.00 14.25 molded package width e1 .463 .472 .482 11.75 12.00 12.25 molded package length d1 .463 .472 .482 11.75 12.00 12.25 pins per side n1 20 20 lead thickness c .004 .006 .008 0.09 0.15 0.20 lead width b .007 .009 .011 0.17 0.22 0.27 mold draft angle top 5 10 15 5 10 15 mold draft angle bottom 5 10 15 5 10 15 ch x 45 significant characteristic
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 360 ? 2004 microchip technology inc. notes:
? 2004 microchip technology inc. ds39609b-page 361 pic18f6520/8520/6620/8620/6720/8720 appendix a: revision history revision a (january 2003) original data sheet for the pic18fxx20 family which includes pic18f6520, pic18f6620, pic18f6720, pic18f8520, pic18f8620 and pic18f8720 devices. this data sheet is based on the previous pic18fxx20 data sheet (ds39580). revision b (january 2004) this revision includes the dc and ac characteristics graphs and tables. the electrical specifications in section 26.0 ?electrical characteristics? have been updated and there have been minor corrections to the data sheet text. appendix b: device differences the differences between the devices listed in this data sheet are shown in table b-1. table b-1: device differences feature pic18f6520 pic18f6620 pic18f6720 pic18f8520 pic18f8620 pic18f8720 on-chip program memory (kbytes) 32 64 128 32 64 128 data memory (bytes) 2048 3840 3840 2048 3840 3840 boot block (bytes) 2048 512 512 2048 512 512 timer1 low-power option yes no no yes no no i/o ports ports a, b, c, d, e, f, g ports a, b, c, d, e, f, g ports a, b, c, d, e, f, g ports a, b, c, d, e, f, g, h, j ports a, b, c, d, e, f, g, h, j ports a, b, c, d, e, f, g, h, j a/d channels 12 12 12 16 16 16 external memory interface no no no yes yes yes maximum operating frequency (mhz) 40 25 25 40 25 25 package types 64-pin tqfp 64-pin tqfp 64-pin tqfp 80-pin tqfp 80-pin tqfp 80-pin tqfp
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 362 ? 2004 microchip technology inc. appendix c: conversion considerations this appendix discusses the considerations for converting from previous versions of a device to the ones listed in this data sheet. typically, these changes are due to the differences in the process technology used. an example of this type of conversion is from a pic17c756 to a pic18f8720. not currently available appendix d: migration from mid-range to enhanced devices a detailed discussion of the differences between the mid-range mcu devices (i.e., pic16cxxx) and the enhanced devices (i.e., pic18fxxx) is provided in an716, ?migrating designs from pic16c74a/74b to pic18c442? . the changes discussed, while device specific, are generally applicable to all mid-range to enhanced device migrations. this application note is available as literature number ds00716.
? 2004 microchip technology inc. ds39609b-page 363 pic18f6520/8520/6620/8620/6720/8720 appendix e: migration from high-end to enhanced devices a detailed discussion of the migration pathway and dif- ferences between the high-end mcu devices (i.e., pic17cxxx) and the enhanced devices (i.e., pic18fxxxx) is provided in an726, ?pic17cxxx to pic18cxxx migration ?. this application note is available as literature number ds00726.
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 364 ? 2004 microchip technology inc. notes:
? 2004 microchip technology inc. ds39609b-page 365 pic18f6520/8520/6620/8620/6720/8720 index a a/d ................................................................................... 213 a/d converter interrupt, configuring ....................... 217 acquisition requirements ........................................ 218 acquisition time ....................................................... 218 adcon0 register .................................................... 213 adcon1 register .................................................... 213 adcon2 register .................................................... 213 adresh register ............................................ 213, 215 adresl register ............................................ 213, 215 analog port pins ...................................................... 128 analog port pins, configuring .................................. 219 associated register summary ................................. 221 calculating minimum required acquisition time (example) ............................. 218 ccp2 trigger ........................................................... 220 configuring the module ............................................ 217 conversion clock (t ad ) ........................................... 219 conversion requirements ....................................... 341 conversion status (go/done bit) .......................... 215 conversion t ad cycles ............................................ 220 conversions ............................................................. 220 converter characteristics ........................................ 340 equations ................................................................. 218 minimum charging time .......................................... 218 special event trigger (ccp) .................................... 152 special event trigger (ccp2) .................................. 220 t ad vs. device operating frequencies (table) ....... 219 absolute maximum ratings ............................................. 307 ac (timing) characteristics ............................................. 320 load conditions for device timing specifications ....................................... 321 parameter symbology ............................................. 320 temperature and voltage specific ations ................. 321 timing conditions .................................................... 321 ackstat status flag ..................................................... 187 adcon0 register ............................................................ 213 go/done bit ........................................................... 215 adcon1 register ............................................................ 213 adcon2 register ............................................................ 213 addlw ............................................................................ 265 addressable universal synchronous asynchronous receiver transmitter (usart) ................................ 197 addwf ............................................................................ 265 addwfc ......................................................................... 266 adresh register .................................................... 213, 215 adresl register .................................................... 213, 215 analog-to-digital converter. see a/d. andlw ............................................................................ 266 andwf ............................................................................ 267 assembler mpasm assembler .................................................. 301 b baud rate generator ....................................................... 183 bc .................................................................................... 267 bcf .................................................................................. 268 bf status flag ................................................................. 187 block diagrams 16-bit byte select mode ............................................. 75 16-bit byte write mode .............................................. 73 16-bit word write mode ............................................. 74 a/d ........................................................................... 216 analog input model .................................................. 217 baud rate generator .............................................. 183 capture mode operation ......................................... 151 comparator analog input model .............................. 227 comparator i/o operating modes (diagram) .......... 224 comparator output .................................................. 226 comparator voltage reference ............................... 230 compare mode operation ....................................... 152 low-voltage detect (lvd) ....................................... 234 low-voltage detect (lvd) with external input ........ 234 mssp (i 2 c master mode) ........................................ 181 mssp (i 2 c mode) .................................................... 166 mssp (spi mode) ................................................... 157 on-chip reset circuit ................................................ 29 pic18f6x20 architecture ............................................ 9 pic18f8x20 architecture .......................................... 10 pll ............................................................................ 23 port/lat/tris operation ..................................... 103 porta ra3:ra0 and ra5 pins ................................... 104 ra4/t0cki pin ................................................ 104 ra6 pin (as i/o) .............................................. 104 portb rb2:rb0 pins .................................................. 107 rb3 pin ........................................................... 107 rb7:rb4 pins .................................................. 106 portc (peripheral output override) ...................... 109 portd and porte parallel slave port ........................................... 128 portd in i/o port mode ......................................... 111 portd in system bus mode .................................. 112 porte in i/o mode ................................................. 115 porte in system bus mode .................................. 115 portf rf1/an6/c2out and rf2/an5/c1out pins ............................ 117 rf6/rf3 and rf0 pins ................................... 118 rf7 pin ........................................................... 118 portg (peripheral output override) ..................... 120 porth rh3:rh0 pins in system bus mode ....... 123 rh3:rh0 pins in i/o mode .............................. 122 rh7:rh4 pins in i/o mode .............................. 122 portj rj4:rj0 pins in system bus mode ................. 126 rj7:rj6 pins in system bus mode ................. 126 portj in i/o mode ................................................. 125 pwm operation (simplified) .................................... 154 reads from flash program memory ......................... 65 single comparator ................................................... 225 table read operation ............................................... 61 table write operation ............................................... 62 table writes to flash program memory .................... 67 timer0 in 16-bit mode .............................................. 132 timer0 in 8-bit mode ................................................ 132 timer1 ..................................................................... 136 timer1 (16-bit r/w mode) ....................................... 136 timer2 ..................................................................... 142 timer3 ..................................................................... 144 timer3 in 16-bit r/w mode ...................................... 144 timer4 ..................................................................... 148 usart receive ...................................................... 206
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 366 ? 2004 microchip technology inc. usart transmit ...................................................... 204 voltage reference output buffer example .............. 231 watchdog timer ....................................................... 251 bn .................................................................................... 268 bnc .................................................................................. 269 bnn .................................................................................. 269 bnov ............................................................................... 270 bnz .................................................................................. 270 bor. see brown-out reset. bov .................................................................................. 273 bra .................................................................................. 271 brg. see baud rate generator. brown-out reset (bor) ..................................................... 30 bsf .................................................................................. 271 btfsc ............................................................................. 272 btfss .............................................................................. 272 btg .................................................................................. 273 bz ..................................................................................... 274 c c compilers mplab c17 ............................................................. 302 mplab c18 ............................................................. 302 mplab c30 ............................................................. 302 call ................................................................................ 274 capture (ccp module) ..................................................... 151 associated registers ............................................... 153 ccp pin configuration ............................................. 151 ccpr1h:ccpr1l registers ................................... 151 software interrupt .................................................... 151 timer1/timer3 mode selection ................................ 151 capture/compare/pwm (ccp) ........................................ 149 capture mode. see capture. ccp mode and timer resources ............................ 150 ccprxh register .................................................... 150 ccprxl register ..................................................... 150 compare mode. see compare. interconnect configurations ..................................... 150 module configuration ............................................... 150 pwm mode. see pwm. capture/compare/pwm requirements (all ccp modules) ................................................... 329 clko and i/o timing requirements ....................... 324, 325 clocking scheme/instruction cycle .................................... 44 clrf ................................................................................ 275 clrwdt .......................................................................... 275 code examples 16 x 16 signed multiply routine ................................ 86 16 x 16 unsigned multiply routine ............................ 86 8 x 8 signed multiply routine .................................... 85 8 x 8 unsigned multiply routine ................................ 85 changing between capture prescalers ................... 151 data eeprom read ................................................. 81 data eeprom refresh routine ................................ 82 data eeprom write ................................................. 81 erasing a flash program memory row ..................... 66 fast register stack .................................................... 44 how to clear ram (bank 1) using indirect addressing .................................. 57 implementing a real-time clock using a timer1 interrupt service .................................. 139 initializing porta .................................................... 103 initializing portb .................................................... 106 initializing portc .................................................... 109 initializing portd .................................................... 111 initializing porte .................................................... 114 initializing portf .................................................... 117 initializing portg ................................................... 120 initializing porth ................................................... 122 initializing portj .................................................... 125 loading the sspbuf (sspsr) register ................. 160 reading a flash program memory word .................. 65 saving status, wreg and bsr registers in ram ............................................................. 102 writing to flash program memory ....................... 68?69 code protection ............................................................... 239 comf .............................................................................. 276 comparator ...................................................................... 223 analog input connection considerations ................ 227 associated registers ............................................... 228 configuration ........................................................... 224 effects of a reset .................................................... 227 interrupts ................................................................. 226 operation ................................................................. 225 operation during sleep ........................................... 227 outputs .................................................................... 225 reference ................................................................ 225 external signal ................................................ 225 internal signal .................................................. 225 response time ........................................................ 225 comparator specifications ............................................... 317 comparator voltage reference ....................................... 229 accuracy and error .................................................. 230 associated registers ............................................... 231 configuring .............................................................. 229 connection considerations ...................................... 230 effects of a reset .................................................... 230 operation during sleep ........................................... 230 compare (ccp module) .................................................. 152 associated registers ............................................... 153 ccp pin configuration ............................................. 152 ccpr1 register ...................................................... 152 software interrupt .................................................... 152 special event trigger .............................. 138, 145, 152 timer1/timer3 mode selection ................................ 152 compare (ccp2 module) special event trigger .............................................. 220 configuration bits ............................................................ 239 context saving during interrupts ..................................... 102 control registers eecon1 and eecon2 ............................................. 62 tablat (table latch) register ................................. 64 tblptr (table pointer) register .............................. 64 conversion considerations .............................................. 362 cpfseq .......................................................................... 276 cpfsgt .......................................................................... 277 cpfslt ........................................................................... 277 d data eeprom memory associated registers ................................................. 83 eeadr register ........................................................ 79 eeadrh register ..................................................... 79 eecon1 register ...................................................... 79 eecon2 register ...................................................... 79 operation during code-protect ................................. 82 protection against spurious write ............................. 82 reading ..................................................................... 81 using ......................................................................... 82 write verify ................................................................ 82 writing ....................................................................... 81
? 2004 microchip technology inc. ds39609b-page 367 pic18f6520/8520/6620/8620/6720/8720 data memory ..................................................................... 47 general purpose registers ........................................ 47 map for pic18fx520 devices ................................... 48 map for pic18fx620/x720 devices .......................... 49 special function registers ........................................ 47 daw ................................................................................. 278 dc and ac characteristics graphs and tables .................................................. 343 dc characteristics pic18fxx20 (industrial and extended), pic18lfxx20 (industrial) ................................ 315 power-down and supply current ............................ 311 supply voltage ......................................................... 310 dcfsnz .......................................................................... 279 decf ............................................................................... 278 decfsz ........................................................................... 279 demonstration boards picdem 1 ................................................................ 304 picdem 17 .............................................................. 304 picdem 18r ........................................................... 305 picdem 2 plus ........................................................ 304 picdem 3 ................................................................ 304 picdem 4 ................................................................ 304 picdem lin ............................................................ 305 picdem usb ........................................................... 305 picdem.net internet/ethernet ................................. 304 development support ...................................................... 301 device differences ........................................................... 361 direct addressing ............................................................... 58 direct addressing ....................................................... 56 e electrical characteristics .................................................. 307 errata ................................................................................... 5 evaluation and programming tools ................................. 305 example spi mode requirements (master mode, cke = 0) .......................................... 331 example spi mode requirements (master mode, cke = 1) .......................................... 332 example spi mode requirements (slave mode, cke = 0) ............................................ 333 example spi slave mode requirements (cke = 1) ........ 334 extended microcontroller mode ......................................... 71 external clock timing requirements ............................... 322 external memory interface ................................................. 71 16-bit byte select mode ............................................. 75 16-bit byte write mode .............................................. 73 16-bit mode ................................................................ 73 16-bit mode timing .................................................... 76 16-bit word write mode ............................................. 74 pic18f8x20 external bus - i/o port functions ......... 72 program memory modes and external memory interface ................................. 71 f firmware instructions ....................................................... 259 flash program memory ..................................................... 61 associated registers ................................................. 69 control registers ....................................................... 62 erase sequence ........................................................ 66 erasing ....................................................................... 66 operation during code-protect ................................. 69 reading ...................................................................... 65 table pointer boundaries based on operation ........................ 64 table pointer boundaries .......................................... 64 table reads and table writes .................................. 61 write sequence ......................................................... 67 writing to .................................................................. 67 protection against spurious writes ................... 69 unexpected termination ................................... 69 write verify ........................................................ 69 g general call address support ......................................... 180 goto .............................................................................. 280 h hardware multiplier ............................................................ 85 introduction ................................................................ 85 operation ................................................................... 85 performance comparison .......................................... 85 hs/pll .............................................................................. 23 i i/o ports .......................................................................... 103 i 2 c bus data requirements (slave mode) ...................... 336 i 2 c bus start/stop bits requirements (slave mode) ....... 335 i 2 c mode general call address support ................................. 180 master mode operation ......................................................... 182 read/write bit information (r/w bit) ............... 170, 171 serial clock (rc3/sck/scl) .................................. 171 id locations ............................................................. 239, 257 incf ................................................................................ 280 incfsz ............................................................................ 281 in-circuit debugger .......................................................... 257 resources (table) ................................................... 257 in-circuit serial programming (icsp) ...................... 239, 257 indirect addressing ............................................................ 58 indf and fsr registers ........................................... 57 operation ................................................................... 57 indirect addressing operation ........................................... 58 indirect file operand ......................................................... 47 infsnz ............................................................................ 281 instruction cycle ................................................................ 44 instruction flow/pipelining ................................................. 45 instruction format ............................................................ 261 instruction set .................................................................. 259 addlw .................................................................... 265 addwf ................................................................... 265 addwfc ................................................................. 266 andlw .................................................................... 266 andwf ................................................................... 267 bc ............................................................................ 267 bcf ......................................................................... 268 bn ............................................................................ 268 bnc ......................................................................... 269 bnn ......................................................................... 269 bnov ...................................................................... 270 bnz ......................................................................... 270 bov ......................................................................... 273 bra ......................................................................... 271 bsf .......................................................................... 271 btfsc ..................................................................... 272 btfss ..................................................................... 272 btg ......................................................................... 273 bz ............................................................................ 274 call ........................................................................ 274 clrf ....................................................................... 275 clrwdt ................................................................. 275
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 368 ? 2004 microchip technology inc. comf ...................................................................... 276 cpfseq .................................................................. 276 cpfsgt .................................................................. 277 cpfslt ................................................................... 277 daw ......................................................................... 278 dcfsnz .................................................................. 279 decf ....................................................................... 278 decfsz ................................................................... 279 goto ...................................................................... 280 incf ......................................................................... 280 incfsz .................................................................... 281 infsnz .................................................................... 281 iorlw ..................................................................... 282 iorwf ..................................................................... 282 lfsr ........................................................................ 283 movf ....................................................................... 283 movff .................................................................... 284 movlb .................................................................... 284 movlw ................................................................... 285 movwf ................................................................... 285 mullw .................................................................... 286 mulwf .................................................................... 286 negf ....................................................................... 287 nop ......................................................................... 287 pop ......................................................................... 288 push ....................................................................... 288 rcall ..................................................................... 289 reset ..................................................................... 289 retfie .................................................................... 290 retlw .................................................................... 290 return .................................................................. 291 rlcf ........................................................................ 291 rlncf ..................................................................... 292 rrcf ....................................................................... 292 rrncf ..................... ............................................... 293 setf ........................................................................ 293 sleep ..................................................................... 294 subfwb .................................................................. 294 sublw .................................................................... 295 subwf .................................................................... 295 subwfb .................................................................. 296 swapf .................................................................... 296 tblrd ..................................................................... 297 tblwt ..................................................................... 298 tstfsz ................................................................... 299 xorlw .................................................................... 299 xorwf .................................................................... 300 summary table ........................................................ 262 int interrupt (rb0/int). see interrupt sources. intcon registers ............................................................. 89 inter-integrated circuit. see i 2 c. interrupt sources .............................................................. 239 a/d conversion complete ....................................... 217 capture complete (ccp) ......................................... 151 compare complete (ccp) ....................................... 152 int0 ......................................................................... 102 interrupt-on-change (rb7:rb4) .............................. 106 portb, interrupt-on-change .................................. 102 rb0/int pin, external .............................................. 102 tmr0 ....................................................................... 102 tmr0 overflow ........................................................ 133 tmr1 overflow ................................................ 135, 138 tmr2 to pr2 match ................................................ 142 tmr2 to pr2 match (pwm) ............................ 141, 154 tmr3 overflow ................................................ 143, 145 tmr4 to pr4 match ................................................ 148 tmr4 to pr4 match (pwm) .................................... 147 interrupts ............................................................................ 87 control registers ....................................................... 89 enable registers ....................................................... 95 flag registers ............................................................ 92 logic .......................................................................... 88 priority registers ....................................................... 98 reset control registers ........................................... 101 iorlw ............................................................................. 282 iorwf ............................................................................. 282 ipr registers ..................................................................... 98 k key features easy migration ............................................................. 7 expanded memory ....................................................... 7 external memory interface ........................................... 7 other special features ................................................ 7 l lfsr ................................................................................ 283 low-voltage detect ......................................................... 233 characteristics ......................................................... 318 converter characteristics ........................................ 318 effects of a reset .................................................... 237 operation ................................................................. 236 current consumption ...................................... 237 during sleep .................................................... 237 reference voltage set point ........................... 237 typical application ................................................... 233 low-voltage icsp programming ..................................... 257 lvd. see low-voltage detect. m master ssp (mssp) module overview .................................................................. 157 master ssp i 2 c bus data requirements ........................ 338 master ssp i 2 c bus start/stop bits requirements ......... 337 master synchronous serial port (mssp). see mssp. memory organization data memory ............................................................. 47 memory programming requirements .............................. 319 microcontroller mode ......................................................... 71 microprocessor mode ........................................................ 71 microprocessor with boot block mode ............................... 71 migration from high-end to enhanced devices ............... 363 migration from mid-range to enhanced devices ............ 362 movf .............................................................................. 283 movff ............................................................................ 284 movlb ............................................................................ 284 movlw ........................................................................... 285 movwf ........................................................................... 285 mplab asm30 assembler, linker, librarian .................. 302 mplab icd 2 in-circuit debugger .................................. 303 mplab ice 2000 high-performance universal in-circuit emulator ................................... 303 mplab ice 4000 high-performance universal in-circuit emulator ................................... 303 mplab integrated development environment software ............................................. 301 mplink object linker/mplib object librarian ............... 302 mssp ............................................................................... 157 ack pulse ....................................................... 170, 171 clock stretching ....................................................... 176 10-bit slave receive mode (sen = 1) ............. 176 10-bit slave transmit mode ............................. 176 7-bit slave receive mode (sen = 1) ............... 176 7-bit slave transmit mode ............................... 176
? 2004 microchip technology inc. ds39609b-page 369 pic18f6520/8520/6620/8620/6720/8720 clock synchronization and the ckp bit ................... 177 control registers (general) ...................................... 157 enabling spi i/o ...................................................... 161 i 2 c mode .................................................................. 166 acknowledge sequence timing ...................... 190 baud rate generator ....................................... 183 bus collision during a repeated start condition .......... 194 bus collision during a start condition ............. 192 bus collision during a stop condition ............. 195 clock arbitration .............................................. 184 effect of a reset .............................................. 191 i 2 c clock rate w/brg ..................................... 183 master mode .................................................... 181 reception ................................................. 187 repeated start timing ............................. 186 master mode start condition ........................... 185 master mode transmission ............................. 187 multi-master communication, bus collision and arbitration ......................................... 191 multi-master mode ........................................... 191 registers .......................................................... 166 sleep operation ............................................... 191 stop condition timing ..................................... 190 i 2 c mode. see i 2 c. module operation .................................................... 170 operation ................................................................. 160 slave mode .............................................................. 170 addressing ....................................................... 170 reception ......................................................... 171 transmission ................................................... 171 spi master mode .................................................... 162 spi clock ......................................................... 162 spi master mode ..................................................... 162 spi mode ................................................................. 157 spi mode. see spi. spi slave mode ....................................................... 163 select synchronization .................................... 163 sspbuf register .................................................... 162 sspsr register ...................................................... 162 typical connection .................................................. 161 mssp module spi master/slave connection .................................. 161 mullw ............................................................................ 286 mulwf ............................................................................ 286 n negf ............................................................................... 287 nop ................................................................................. 287 o opcode field descriptions ............................................... 260 option_reg register psa bit ..................................................................... 133 t0cs bit ................................................................... 133 t0ps2:t0ps0 bits ................................................... 133 t0se bit ................................................................... 133 oscillator configuration ...................................................... 21 ec .............................................................................. 21 ecio .......................................................................... 21 hs .............................................................................. 21 hs + pll ................................................................... 21 lp ............................................................................... 21 rc .............................................................................. 21 rcio .......................................................................... 21 xt .............................................................................. 21 oscillator selection .......................................................... 239 oscillator switching feature .............................................. 24 oscillator transitions ................................................. 26 system clock switch bit ............................................ 25 oscillator, timer1 ............................................. 135, 137, 145 oscillator, timer3 ............................................................. 143 oscillator, wdt ................................................................ 250 p packaging information ..................................................... 357 details ...................................................................... 358 marking .................................................................... 357 parallel slave port (psp) ......................................... 111, 128 associated registers ............................................... 130 re0/rd /an5 pin ..................................................... 128 re1/wr /an6 pin .................................................... 128 re2/cs /an7 pin ..................................................... 128 read waveforms ..................................................... 130 select (pspmode bit) .................................... 111, 128 write waveforms ..................................................... 129 parallel slave port requirements (pic18f8x20) ............ 330 pickit 1 flash starter kit ................................................. 305 picstart plus development programmer .................... 303 pie registers ..................................................................... 95 pin functions av dd .......................................................................... 20 av ss .......................................................................... 20 mclr /v pp ................................................................. 11 osc1/clki ................................................................ 11 osc2/clko/ra6 ...................................................... 11 ra0/an0 .................................................................... 12 ra1/an1 .................................................................... 12 ra2/an2/v ref - ......................................................... 12 ra3/an3/v ref + ........................................................ 12 ra4/t0cki ................................................................ 12 ra5/an4/lvdin ........................................................ 12 ra6 ............................................................................ 12 rb0/int0 ................................................................... 13 rb1/int1 ................................................................... 13 rb2/int2 ................................................................... 13 rb3/int3/ccp2 ........................................................ 13 rb4/kbi0 ................................................................... 13 rb5/kbi1/pgm .......................................................... 13 rb6/kbi2/pgc .......................................................... 13 rb7/kbi3/pgd .......................................................... 13 rc0/t1oso/t13cki ................................................. 14 rc1/t1osi/ccp2 ..................................................... 14 rc2/ccp1 ................................................................. 14 rc3/sck/scl ........................................................... 14 rc4/sdi/sda ............................................................ 14 rc5/sdo ................................................................... 14 rc6/tx1/ck1 ............................................................ 14 rc7/rx1/dt1 ............................................................ 14 rd0/psp0/ad0 ......................................................... 15 rd1/psp1/ad1 ......................................................... 15 rd2/psp2/ad2 ......................................................... 15 rd3/psp3/ad3 ......................................................... 15 rd4/psp4/ad4 ......................................................... 15 rd5/psp5/ad5 ......................................................... 15 rd6/psp6/ad6 ......................................................... 15 rd7/psp7/ad7 ......................................................... 15 re0/rd /ad8 ............................................................. 16 re1/wr /ad9 ............................................................. 16 re2/cs /ad10 ............................................................ 16 re3/ad11 .................................................................. 16
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 370 ? 2004 microchip technology inc. re4/ad12 .................................................................. 16 re5/ad13 .................................................................. 16 re6/ad14 .................................................................. 16 re7/ccp2/ad15 ....................................................... 16 rf0/an5 .................................................................... 17 rf1/an6/c2out ....................................................... 17 rf2/an7/c1out ....................................................... 17 rf3/an8 .................................................................... 17 rf4/an9 .................................................................... 17 rf5/an10/cv ref ....................................................... 17 rf6/an11 .................................................................. 17 rf7/ss ...................................................................... 17 rg0/ccp3 ................................................................. 18 rg1/tx2/ck2 ............................................................ 18 rg2/rx2/dt2 ............................................................ 18 rg3/ccp4 ................................................................. 18 rg4/ccp5 ................................................................. 18 rh0/a16 .................................................................... 19 rh1/a17 .................................................................... 19 rh2/a18 .................................................................... 19 rh3/a19 .................................................................... 19 rh4/an12 .................................................................. 19 rh5/an13 .................................................................. 19 rh6/an14 .................................................................. 19 rh7/an15 .................................................................. 19 rj0/ale ..................................................................... 20 rj1/oe ...................................................................... 20 rj2/wrl .................................................................... 20 rj3/wrh ................................................................... 20 rj4/ba0 ..................................................................... 20 rj5/ce ....................................................................... 20 rj6/lb ....................................................................... 20 rj7/ub ....................................................................... 20 v dd ............................................................................. 20 v ss ............................................................................. 20 pir registers ..................................................................... 92 pll clock timing specifications ...................................... 323 pll lock time-out ............................................................. 30 pointer, fsr ....................................................................... 57 pop .................................................................................. 288 por. see power-on reset. porta associated registers ............................................... 105 functions ................................................................. 105 lata register .......................................................... 103 porta register ...................................................... 103 trisa register ........................................................ 103 portb associated registers ............................................... 108 functions ................................................................. 108 latb register .......................................................... 106 portb register ...................................................... 106 rb0/int pin, external .............................................. 102 trisb register ........................................................ 106 portc associated registers ............................................... 110 functions ................................................................. 110 latc register ......................................................... 109 portc register ...................................................... 109 rc3/sck/scl pin ................................................... 171 trisc register ................................................ 109, 197 portd ............................................................................ 128 associated registers ............................................... 113 functions ................................................................. 113 latd register ......................................................... 111 parallel slave port (psp) function .......................... 111 portd register ...................................................... 111 trisd register ........................................................ 111 porte analog port pins ...................................................... 128 associated registers ............................................... 116 functions ................................................................. 116 late register ......................................................... 114 porte register ...................................................... 114 psp mode select (pspmode bit) .................. 111, 128 re0/rd /an5 pin ..................................................... 128 re1/wr /an6 pin ..................................................... 128 re2/cs /an7 pin ...................................................... 128 trise register ........................................................ 114 portf associated registers ............................................... 119 functions ................................................................. 119 latf register .......................................................... 117 portf register ...................................................... 117 trisf register ........................................................ 117 portg associated registers ............................................... 121 functions ................................................................. 121 latg register ......................................................... 120 portg register ...................................................... 120 trisg register ............................................... 120, 197 porth associated registers ............................................... 124 functions ................................................................. 124 lath register ......................................................... 122 porth register ...................................................... 122 trish register ........................................................ 122 portj associated registers ............................................... 127 functions ................................................................. 127 latj register .......................................................... 125 portj register ....................................................... 125 trisj register ........................................................ 125 postscaler, wdt assignment (psa bit) .............................................. 133 rate select (t0ps2:t0ps0 bits) ............................. 133 switching between timer0 and wdt ...................... 133 power-down mode. see sleep. power-on reset (por) ...................................................... 30 oscillator start-up timer (ost) ................................. 30 power-up timer (pwrt) ........................................... 30 time-out sequence ................................................... 30 prescaler, capture ........................................................... 151 prescaler, timer0 ............................................................ 133 assignment (psa bit) .............................................. 133 rate select (t0ps2:t0ps0 bits) ............................. 133 switching between timer0 and wdt ...................... 133 prescaler, timer2 ............................................................ 154 pro mate ii universal device programmer .................. 303 product identification system .......................................... 377 program counter pcl, pclath and pclatu registers ..................... 44
? 2004 microchip technology inc. ds39609b-page 371 pic18f6520/8520/6620/8620/6720/8720 program memory ............................................................... 39 access for pic18f8x20 program memory modes .................................................. 40 instructions ................................................................. 45 interrupt vector .......................................................... 39 map and stack for pic18fxx20 ................................ 40 maps for pic18f8x20 program memory modes ....... 41 pic18f8x20 modes ................................................... 39 reset vector .............................................................. 39 program memory write timing requirements ................. 326 program verification and code protection ....................... 253 associated registers ............................................... 253 configuration register protection ............................ 257 data eeprom code protection .............................. 257 memory code protection ......................................... 255 programming, device instructions ................................... 259 psp. see parallel slave port. pulse width modulation. see pwm (ccp module). push ............................................................................... 288 pwm (ccp module) ........................................................ 154 associated registers ............................................... 155 ccpr1h:ccpr1l registers ................................... 154 duty cycle ................................................................ 154 example frequencies/resolutions .......................... 155 period ....................................................................... 154 setup for pwm operation ........................................ 155 tmr2 to pr2 match ........................................ 141, 154 tmr4 to pr4 match ................................................ 147 q q clock ............................................................................ 154 r ram. see data memory. rc oscillator ...................................................................... 22 rcall ............................................................................. 289 rcon registers .............................................................. 101 rcsta register spen bit .................................................................. 197 register file ....................................................................... 47 registers adcon0 (a/d control 0) ......................................... 213 adcon1 (a/d control 1) ......................................... 214 adcon2 (a/d control 2) ......................................... 215 ccpxcon (capture/compare/pwm control) ......... 149 cmcon (comparator control) ................................ 223 config1h (configuration 1 high) .......................... 240 config2h (configuration 2 high) .......................... 241 config2l (configuration 2 low) ............................ 241 config3h (configuration 3 high) .......................... 242 config3l (configuration 3 low) ............................ 242 config3l (configuration byte) ................................ 41 config4l (configuration 4 low) ............................ 243 config5h (configuration 5 high) .......................... 245 config5l (configuration 5 low) ............................ 244 config6h (configuration 6 high) .......................... 247 config6l (configuration 6 low) ............................ 246 config7h (configuration 7 high) .......................... 249 config7l (configuration 7 low) ............................ 248 cvrcon (comparator voltage reference control) .......................................... 229 device id 1 .............................................................. 249 device id 2 .............................................................. 249 eecon1 (data eeprom control 1) ................... 63, 80 intcon (interrupt control) ........................................ 89 intcon2 (interrupt control 2) ................................... 90 intcon3 (interrupt control 3) ................................... 91 ipr1 (peripheral interrupt priority 1) ......................... 98 ipr2 (peripheral interrupt priority 2) ......................... 99 ipr3 (peripheral interrupt priority 3) ....................... 100 lvdcon (low-voltage detect control) .................. 235 memcon (memory control) ..................................... 71 osccon ................................................................... 25 pie1 (peripheral interrupt enable 1) ......................... 95 pie2 (peripheral interrupt enable 2) ......................... 96 pie3 (peripheral interrupt enable 3) ......................... 97 pir1 (peripheral interrupt request 1) ....................... 92 pir2 (peripheral interrupt request 2) ....................... 93 pir3 (peripheral interrupt request 3) ....................... 94 pspcon (parallel slave port control) register ........................................................... 129 rcon ........................................................................ 31 rcon (reset control) ....................................... 60, 101 rcstax (receive status and control) ................... 199 sspcon2 (mssp control 2, i 2 c mode) ................. 169 sspstat (mssp status, i 2 c mode) ...................... 167 sspstat (mssp status, spi mode) ...................... 158 status ........................................................................ 59 stkptr (stack pointer) ............................................ 43 summary ............................................................. 52?55 t1con (timer 1 control) ........................................ 135 t3con (timer3 control) ......................................... 143 txstax (transmit status and control) ................... 198 wdtcon (watchdog timer control) ...................... 250 reset ................................................................. 29, 239, 289 brown-out reset (bor) ........................................... 239 mclr reset .............................................................. 29 mclr reset during sleep ......................................... 29 oscillator start-up timer (ost) ............................... 239 power-on reset (por) ...................................... 29, 239 power-up timer (pwrt) ......................................... 239 programmable brown-out reset (pbor) .................. 29 reset instruction ........................................................ 29 stack full reset ........................................................ 29 stack underflow reset .............................................. 29 watchdog timer (wdt) reset .................................. 29 reset, watchdog timer, oscillator start-up timer, power-up timer and brown-out reset requirements .......................................................... 327 retfie ............................................................................ 290 retlw ............................................................................ 290 return .......................................................................... 291 return address stack and associated registers .......................................... 43 revision history ............................................................... 361 rlcf ............................................................................... 291 rlncf ............................................................................. 292 rrcf ............................................................................... 292 rrncf ..................................... ....................................... 293 s sci. see usart. sck ................................................................................. 157 sdi ................................................................................... 157 sdo ................................................................................. 157 serial clock, sck ............................................................ 157 serial communication interface. see usart. serial data in, sdi ........................................................... 157 serial data out, sdo ...................................................... 157 serial peripheral interface. see spi. setf ............................................................................... 293 slave select, ss .............................................................. 157 sleep ............................................................................. 294 sleep ....................................................................... 239, 252
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 372 ? 2004 microchip technology inc. software simulator (mplab sim) .................................... 302 software simulator (mplab sim30) ................................ 302 special event trigger. see compare special features of the cpu ............................................ 239 configuration registers ................................... 240?249 special function registers ................................................ 47 map ............................................................................ 50 spi serial clock .............................................................. 157 serial data in ........................................................... 157 serial data out ........................................................ 157 slave select ............................................................. 157 spi mode ................................................................. 157 spi master/slave connection .......................................... 161 spi module associated registers ............................................... 165 bus mode compatibility ........................................... 165 effects of a reset ..................................................... 165 master/slave connection ......................................... 161 slave mode .............................................................. 163 sleep operation ....................................................... 165 ss .................................................................................... 157 ssp tmr2 output for clock shift ............................ 141, 142 tmr4 output for clock shift .................................... 148 sspov status flag .......................................................... 187 sspstat register r/w bit ............................................................. 170, 171 status bits significance and initialization condition for rcon register ............................................. 31 subfwb .......................................................................... 294 sublw ............................................................................ 295 subwf ............................................................................ 295 subwfb .......................................................................... 296 swapf ............................................................................ 296 t table pointer operations (table) ........................................ 64 tblrd ............................................................................. 297 tblwt ............................................................................. 298 time-out in various situations ........................................... 31 timer0 .............................................................................. 131 16-bit mode timer reads and writes ...................... 133 associated registers ............................................... 133 clock source edge select (t0se bit) ...................... 133 clock source select (t0cs bit) ............................... 133 operation ................................................................. 133 overflow interrupt .................................................... 133 prescaler. see prescaler, timer0. timer0 and timer1 external clock requirements ........................................................... 328 timer1 .............................................................................. 135 16-bit read/write mode ........................................... 138 associated registers ............................................... 139 operation ................................................................. 136 oscillator .......................................................... 135, 137 overflow interrupt ............................................ 135, 138 special event trigger (ccp) ............................ 138, 152 tmr1h register ...................................................... 135 tmr1l register ....................................................... 135 use as a real-time clock ....................................... 138 timer2 .............................................................................. 141 associated registers ............................................... 142 operation ................................................................. 141 postscaler. see postscaler, timer2. pr2 register ................................................... 141, 154 prescaler. see prescaler, timer2. ssp clock shift ............................................... 141, 142 tmr2 register ......................................................... 141 tmr2 to pr2 match interrupt .................. 141, 142, 154 timer3 .............................................................................. 143 associated registers ............................................... 145 operation ................................................................. 144 oscillator .......................................................... 143, 145 overflow interrupt ............................................ 143, 145 special event trigger (ccp) ................................... 145 tmr3h register ...................................................... 143 tmr3l register ....................................................... 143 timer4 .............................................................................. 147 associated registers ............................................... 148 operation ................................................................. 147 postscaler. see postscaler, timer4. pr4 register ........................................................... 147 prescaler. see prescaler, timer4. ssp clock shift ....................................................... 148 tmr4 register ......................................................... 147 tmr4 to pr4 match interrupt .......................... 147, 148 timing diagrams a/d conversion ........................................................ 340 acknowledge sequence .......................................... 190 baud rate generator with clock arbitration ............ 184 brg reset due to sda arbitration during start condition ..................................... 193 brown-out reset (bor) ........................................... 327 bus collision during a repeated start condition (case 1) .................................. 194 bus collision during a repeated start condition (case 2) .................................. 194 bus collision during a stop condition (case 1) ........................................................... 195 bus collision during a stop condition (case 2) ........................................................... 195 bus collision during start condition (scl = 0) ......................................................... 193 bus collision during start condition (sda only) ....................................................... 192 bus collision for transmit and acknowledge .......... 191 capture/compare/pwm (all ccp modules) ............ 328 clko and i/o .......................................................... 323 clock synchronization ............................................. 177 clock/instruction cycle .............................................. 44 example spi master mode (cke = 0) ..................... 330 example spi master mode (cke = 1) ..................... 331 example spi slave mode (cke = 0) ....................... 332 example spi slave mode (cke = 1) ....................... 333 external clock (all modes except pll) ................... 322 external memory bus for sleep (microprocessor mode) ...................................... 77 external memory bus for tblrd (extended microcontroller mode) ...................... 76 external memory bus for tblrd (microprocessor mode) ...................................... 76 i 2 c bus data ............................................................ 335 i 2 c bus start/stop bits ............................................ 334 i 2 c master mode (7 or 10-bit transmission) ............ 188 i 2 c master mode (7-bit reception) .......................... 189
? 2004 microchip technology inc. ds39609b-page 373 pic18f6520/8520/6620/8620/6720/8720 i 2 c master mode first start bit timing .................... 185 i 2 c slave mode (10-bit reception, sen = 0) ........... 174 i 2 c slave mode (10-bit reception, sen = 1) ........... 179 i 2 c slave mode (10-bit transmission) ..................... 175 i 2 c slave mode (7-bit reception, sen = 0) ............. 172 i 2 c slave mode (7-bit reception, sen = 1) ............. 178 i 2 c slave mode (7-bit transmission) ....................... 173 low-voltage detect .................................................. 236 master ssp i 2 c bus data ........................................ 337 master ssp i 2 c bus start/stop bits ........................ 337 parallel slave port (pic18f8x20) ........................... 329 program memory read ............................................ 324 program memory write ............................................ 325 pwm output ............................................................ 154 repeat start condition ............................................. 186 reset, watchdog timer (wdt), oscillator start-up timer (ost) and power-up timer (pwrt) ................................. 326 slave mode general call address sequence (7 or 10-bit address mode) .............................. 180 slave synchronization ............................................. 163 slow rise time (mclr tied to v dd via 1 kohm resistor) ......................................... 38 spi mode (master mode) ......................................... 162 spi mode (slave mode with cke = 0) ..................... 164 spi mode (slave mode with cke = 1) ..................... 164 stop condition receive or transmit mode .............. 190 synchronous reception (master mode, sren) ..................................... 210 synchronous transmission ...................................... 209 synchronous transmission (through txen) .......... 209 time-out sequence on por w/pll enabled (mclr tied to v dd via 1 kohm resistor) ......... 38 time-out sequence on power-up (mclr not tied to v dd ) case 1 ............................................................... 37 case 2 ............................................................... 37 time-out sequence on power-up (mclr tied to v dd via 1 kohm resistor) .............................. 37 timer0 and timer1 external clock .......................... 327 timing for transition between timer1 and osc1 (hs with pll) .......................................... 27 transition between timer1 and osc1 (hs, xt, lp) ...................................................... 26 transition between timer1 and osc1 (rc, ec) ....... 27 transition from osc1 to timer1 oscillator ................ 26 usart asynchronous reception ............................ 207 usart asynchronous transmission ....................... 205 usart asynchronous transmission (back to back) ................................................. 205 usart synchronous receive ( master/slave) ....... 339 usart synchronous transmission (master/slave) ................................................. 339 wake-up from sleep via interrupt ............................ 253 trise register pspmode bit .................................................. 111, 128 tstfsz ........................................................................... 299 two-word instructions example cases .......................................................... 46 txsta register brgh bit ................................................................. 200 u universal synchronous asynchronous receiver transmitter. see usart. usart asynchronous mode ................................................ 204 associated registers, receive ........................ 207 associated registers, transmit ....................... 205 receiver .......................................................... 206 setting up 9-bit mode with address detect ..... 206 transmitter ...................................................... 204 baud rate generator (brg) ................................... 200 associated registers ....................................... 200 baud rate error, calculating ........................... 200 baud rate formula ......................................... 200 baud rates for asynchronous mode (brgh = 0) .............................................. 202 baud rates for asynchronous mode (brgh = 1) .............................................. 203 baud rates for synchronous mode ................. 201 high baud rate select (brgh bit) ................. 200 sampling ......................................................... 200 serial port enable (spen bit) ................................. 197 synchronous master mode ...................................... 208 associated registers, reception ..................... 210 associated registers, transmit ....................... 208 reception ........................................................ 210 transmission ................................................... 208 synchronous slave mode ........................................ 211 associated registers, receive ........................ 212 associated registers, transmit ....................... 211 reception ........................................................ 212 transmission ................................................... 211 usart synchronous receive requirements ................. 339 usart synchronous transmission requirements ......... 339 v voltage reference specifications .................................... 317 w wake-up from sleep ................................................ 239, 252 using interrupts ....................................................... 252 watchdog timer (wdt) ........................................... 239, 250 associated registers ............................................... 251 control register ....................................................... 250 postscaler ................................................................ 251 programming considerations .................................. 250 rc oscillator ........................................................... 250 time-out period ....................................................... 250 wcol .............................................................................. 185 wcol status flag ................................... 185, 186, 187, 190 wdt postscaler ............................................................... 250 www, on-line support ................... ................................... 5 x xorlw ........................................................................... 299 xorwf ........................................................................... 300
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 374 ? 2004 microchip technology inc. notes:
? 2004 microchip technology inc. ds39609b-page 375 pic18f6520/8520/6620/8620/6720/8720 on-line support microchip provides on-line support on the microchip world wide web site. the web site is used by microchip as a means to make files and information easily available to customers. to view the site, the user must have access to the internet and a web browser, such as netscape ? or microsoft ? internet explorer. files are also available for ftp download from our ftp site. connecting to the microchip internet web site the microchip web site is available at the following url: www.microchip.com the file transfer site is available by using an ftp service to connect to: ftp://ftp.microchip.com the web site and file transfer site provide a variety of services. users may download files for the latest development tools, data sheets, application notes, user?s guides, articles and sample programs. a variety of microchip specific business information is also available, including listings of microchip sales offices, distributors and factory representatives. other data available for consideration is: latest microchip press releases technical support section with frequently asked questions design tips device errata job postings microchip consultant program member listing links to other useful web sites related to microchip products conferences for products, development systems, technical information and more listing of seminars and events systems information and upgrade hot line the systems information and upgrade line provides system users a listing of the latest versions of all of microchip?s development systems software products. plus, this line provides information on how customers can receive the most current upgrade kits. the hot line numbers are: 1-800-755-2345 for u.s. and most of canada, and 1-480-792-7302 for the rest of the world. 042003
pic18f6520/8520/6620/8620/6720/8720 ds39609b-page 376 ? 2004 microchip technology inc. reader response it is our intention to provide you with the best documentation possible to ensure successful use of your microchip prod- uct. if you wish to provide your comments on organization, clarity, subject matter, and ways in which our documentation can better serve you, please fax your comments to the technical publications manager at (480) 792-4150. please list the following information, and use this outline to provide us with your comments about this document. to : technical publications manager re: reader response total pages sent ________ from: name company address city / state / zip / country telephone: (_______) _________ - _________ application (optional): would you like a reply? y n device: literature number: questions: fax: (______) _________ - _________ ds39609b pic18f6520/8520/6620/8620/6720/8720 1. what are the best features of this document? 2. how does this document meet your hardware and software development needs? 3. do you find the organization of this document easy to follow? if not, why? 4. what additions to the document do you think would enhance the structure and subject? 5. what deletions from the document could be made without affecting the overall usefulness? 6. is there any incorrect or misleading information (what and where)? 7. how would you improve this document?
? 2004 microchip technology inc. ds39609b-page 377 pic18f6520/8520/6620/8620/6720/8720 pic18f6520/8520/6620/8620/6720/872 0 product identification system to order or obtain information, e.g., on pricing or delivery, refer to the factory or the listed sales office. part no. ? x /xx xxx pattern package temperature range device device pic18f6520/8520/6620/8620/6720/8720 (1) , pic18f6520/8520/6620/8620/6720/8720t (2) ; v dd range 4.2v to 5.5v pic18lf6520/8520/6620/8620/6720/8720 (1) , pic18lf6520/8520/6620/8620/6720/8720t (2) ; v dd range 2.0v to 5.5v temperature range i= -40 c to +85 c (industrial) e= -40 c to +125 c (extended) package pt = tqfp (thin quad flatpack) pattern qtp, sqtp, code or special requirements (blank otherwise) examples: a) pic18lf6620-i/pt 301 = industrial temp., tqfp package, extended v dd limits, qtp pattern #301. b) pic18f8720-i/pt = industrial temp., tqfp package, normal v dd limits. c) pic18f8620-e/pt = extended temp., tqfp package, standard v dd limits. note 1: f = standard voltage range lf = extended voltage range 2: t = in tape and reel
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