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features ? incorporates the arm7tdmi ? arm ? thumb ? processor ? high-performance 32-bit risc architecture ? high-density 16-bit instruction set ? leader in mips/watt embeddedice ? in-circuit emulation, debug communication channel support 256 kbytes of internal hi gh-speed flash, organized in 1024 pages of 256 bytes ? single cycle access at up to 30 mhz in worst case conditions ? prefetch buffer optimizing thumb instruction executi on at maximum speed ? page programming time: 6 ms, including pa ge auto-erase, full erase time: 15 ms ? 10,000 write cycles, 10-year data retent ion capability, sector lock capabilities 32k bytes of internal high-speed sram , single-cycle access at maximum speed memory controller (mc) ? embedded flash controller, abort status and misalignment detection ? memory protection unit reset controller (rstc) ? based on three power-on reset cells ? provides external reset signal shaping and reset sources status clock generator (ckgr) ? low-power rc oscillator, 3 to 20 mhz on-chip oscillator and one pll power management controller (pmc) ? power optimization capabilities, including slow clock mode (down to 500 hz), idle mode, standby mode and backup mode ? four programmable external clock signals advanced interrupt controller (aic) ? individually maskable, eight-level priority, vectored interrupt sources ? four external interrupt sources and one f ast interrupt source, spurious interrupt protected debug unit (dbgu) ? 2-wire uart and support for debug communication channel interrupt periodic interval timer (pit) ? 20-bit programmable counter pl us 12-bit interval counter windowed watchdog (wdt) ? 12-bit key-protected programmable counter ? provides reset or interrupt signal to the system ? counter may be stopped while the processor is in debug mode or in idle state real-time timer (rtt) ? 32-bit free-running counter with alarm ? runs off the internal rc oscillator two parallel input/output controllers (pio) ? sixty-two programmable i/o lines multiplexed with up to two peripheral i/os ? input change interrupt capability on each i/o line ? individually programmable open-drain, pull-up resistor and synchronous output shutdown controller (shdwc) ? programmable shutdown pin and wake-up circuitry two 32-bit battery backup registers for a total of 8 bytes one 8-channel 20-bit pwm controller (pwmc) one usb 2.0 full sp eed (12 mbits per second) device port ? on-chip transceiver, 2376-byte configurable integrated fifos at91 arm thumb-based microcontrollers at91sam7a3 preliminary 6042e?atarm?14-dec-06
2 6042e?atarm?14-dec-06 at91sam7a3 preliminary nineteen peripheral dma controller (pdc) channels two can 2.0b active controllers, supporting 11-b it standard and 29-bit extended identifiers ? 16 fully programmable message object mailboxes, 16-bit time stamp counter two 8-channel 10-bit anal og-to-digital converter three universal synchronous/asynchro nous receiver transmitters (usart) ? individual baud rate generator, irda ? infrared modulation/demodulation ? support for iso7816 t0/t1 smart card, hardware handshaking, rs485 support two master/slave serial peripheral interfaces (spi) ? 8- to 16-bit programmable da ta length, four external peripheral chip selects three 3-channel 16-bit timer/counters (tc) ? three external clock inputs, two multi-purpose i/o pins per channel ? double pwm generation, capture/waveform mode, up/down capability two synchronous serial controllers (ssc) ? independent clock and frame sync sign als for each receiver and transmitter ? i2s analog interface support, time division multiplex support ? high-speed continuous data stream ca pabilities with 32-bit data transfer one two-wire interface (twi) ? master mode support only, all two-wire atmel eeprom?s supported multimedia card interface (mci) ? compliant with multimedia cards and sd cards ? automatic protocol control and fast automatic da ta transfers with pdc, mmc and sdcard compliant ieee ? 1149.1 jtag boundary sc an on all digital pins required power supplies ? embedded 1.8v regulator, drawing up to 130 ma for the core and the external components, enables 3.3v single supply mode ? 3.3v vdd3v3 regulator, i/o lines and flash power supply ? 1.8v vdd1v8 output of the voltage regulator and core power supply ? 3v to 3.6v vddana adc power supply ? 3v to 3.6v vddbu backup power supply 5v-tolerant i/os fully static operation: up to 60 mhz at 1.65v and 85c worst case conditions available in a 100-lead lqfp green package
3 6042e?atarm?14-dec-06 at91sam7a3 preliminary 1. description the at91sam7a3 is a member of a series of 32-bit arm7 ? microcontrollers with an inte- grated can controller. it features a 256-kbyt e high-speed flash and 32-kbyte sram, a large set of peripherals, including two 2.0b full can controllers, and a complete set of system func- tions minimizing the number of external component s. the device is an ideal migration path for 8-bit microcontroller users looking for additional performance and extended memory. the embedded flash memory can be programmed in-system via the jtag-ice interface. built-in lock bits protect the firmware from accidental overwrite. the at91sam7a3 integrates a complete set of features facilitating debug, including a jtag embedded ice interface, misalignment detector, interrupt driven debug communication chan- nel for user configurable trace on a console, and jtag boundary scan for board level debug and test. by combining a high-performance 32-bit risc processor with a high-density 16-bit instruction set, flash and sram memory, a wide range of peripherals including can controllers, 10-bit adc, timers and serial communication channel s, on a monolithic chip, the at91sam7a3 is ideal for many compute-intensive embedded control applications.
4 6042e?atarm?14-dec-06 at91sam7a3 preliminary 2. block diagram figure 2-1. at91sam7a3 block diagram tf0 tk0 td0 rd0 rk0 rf0 tclk0 tclk1 tclk2 tioa0 tiob0 tioa1 tiob1 tioa2 tiob2 canrx0 cantx0 canrx1 cantx1 tf1 tk1 td1 rd1 rk1 rf1 tclk3 tclk4 tclk5 tioa3 tiob3 tioa4 tiob4 tioa5 tiob5 tclk6 tclk7 tclk8 tioa6 tiob6 tioa7 tiob7 tioa8 tiob8 twd twck pwm0 pwm1 pwm2 pwm3 pwm4 pwm5 pwm6 pwm7 ddm ddp tdi tdo tms tck peripheral bridge peripheral data controller 19 channels sram 32k bytes arm7tdmi processor ice jtag scan jtagsel usart0 ssc0 timer counter rxd0 txd0 sck0 rts0 cts0 spi0_npcs0 spi0_npcs1 spi0_npcs2 spi0_npcs3 spi0_miso spi0_mosi spi0_spck flash 256k bytes memory controller memory protection unit abort status address decoder misalignment detection pio pio apb embedded flash controller adc0_ad0 adc0_ad1 adc0_ad2 adc0_ad3 adc0_ad4 adc0_ad5 adc0_ad6 adc0_ad7 can0 adc0_adtrg pdc pdc usart1 rxd1 txd1 sck1 rts1 cts1 pdc pdc pdc pdc spi0 spi1_npcs0 spi1_npcs1 spi1_npcs2 spi1_npcs3 spi1_miso spi1_mosi spi1_spck pdc pdc spi1 pdc adc0 gnd vddana advrefp can1 pdc pdc ssc1 pdc pdc tc0 tc1 tc2 timer counter tc3 tc4 tc5 timer counter tc6 tc7 tc8 twi vdd3v3 gnd vdd1v8 rxd2 txd2 sck2 rts2 cts2 usart2 pdc pdc adc1 pdc adc1_adtrg adc1_ad0 adc1_ad1 adc1_ad2 adc1_ad3 adc1_ad4 adc1_ad5 adc1_ad6 adc1_ad7 pwmc 1.8 v voltage regulator mcck mccda mcda0-mcda3 mci pdc usb device fifo transceiver nrst fiq irq0-irq3 pck0-pck3 pmc aic pll rcosc piob reset controller drxd dtxd por pllrc osc xin xout por vddbu tst dbgu pdc pdc pio pit wdt rtt system controller vdd3v3 pioa vdd1v8 por shutdown controller fwkup wkup0 wkup1 shdw gnd vddbu gpbr pdc
5 6042e?atarm?14-dec-06 at91sam7a3 preliminary 3. signal description table 3-1. signal description signal name function type active level comments power vdd3v3 1.8v voltage regulator, i/o lines and flash power supply power 3.0v to 3.6v vddbu backup i/o lines power supply power 3v to 3.6v vddana analog power supply power 3v to 3.6v vdd1v8 1.8v voltage regulator output and core power supply power 1.85v typical vddpll 1.8v pll power supply power 1.65v to 1.95v gnd ground ground clocks, oscillators and plls xin main oscillator input input xout main oscillator output output pllrc pll filter input pck0 - pck3 programmable clock output output shdw shut-down control output open drain. wkup0 - wkup1 wake-up inputs input accept between 0v and vddbu fwkup force wake up input accept between 0v and vddbu external pull-up resistor needed. ice and jtag tck test clock input no pull-up resistor tdi test data in input no pull-up resistor tdo test data out output tms test mode select input no pull-up resistor jtagsel jtag selection input pull-down resistor reset/test nrst microcontroller reset i/o low tst test mode select input high pull-down resistor debug unit drxd debug receive data input dtxd debug transmit data output
6 6042e?atarm?14-dec-06 at91sam7a3 preliminary aic irq0 - irq3 external interrupt inputs input fiq fast interrupt input input pio pa0 - pa31 parallel io controller a i/o pulled-up input at reset pb0 - pb29 parallel io controller b i/o pulled-up input at reset multimedia card interface mcck multimedia card clock output mccda multimedia card a command i/o mcda0 - mcda3 multimedia card a data i/o usb device port ddm usb device port data - analog ddp usb device port data + analog usart sck0 - sck1 - sck2 serial clock i/o txd0 - txd1 - txd2 transmit data i/o rxd0 - rxd1 - rxd2 receive data input rts0 - rts1 - rts2 request to send output cts0 - cts1 - cts2 clear to send input synchronous serial controller td0 - td1 transmit data output rd0 - rd1 receive data input tk0 - tk1 transmit clock i/o rk0 - rk1 receive clock i/o tf0 - tf1 transmit frame sync i/o rf0 - rf1 receive frame sync i/o timer/counter tclk0 - tclk8 external clock input input tioa0 - tioa8 i/o line a i/o tiob0 - tiob8 i/o line b i/o pwm controller pwm0 - pwm7 pwm channels output table 3-1. signal description (continued) signal name function type active level comments
7 6042e?atarm?14-dec-06 at91sam7a3 preliminary spi spi0_miso spi1_miso master in slave out i/o spi0_mosi spi1_mosi master out slave in i/o spi0_spck spi1_spck spi serial clock i/o spi0_npcs0 spi1_npcs0 spi peripheral chip select 0 i/o low spi0_npcs1 - spi0_npcs3 spi1_npcs1 - spi1_npcs3 spi peripheral chip select output low two-wire interface twd two-wire serial data i/o twck two-wire serial clock i/o analog-to-digit al converter adc0_ad0 - adc0_ad7 adc1_ad0 - adc1_ad7 analog inputs analog digital pulled-up inputs at reset advrefp analog positive reference analog adc0_adtrg adc1_adtrg adc trigger input can controller canrx0-canrx1 can inputs input cantx0-cantx1 can outputs output table 3-1. signal description (continued) signal name function type active level comments
8 6042e?atarm?14-dec-06 at91sam7a3 preliminary 4. package 4.1 100-lead lqfp package outline figure 4-1 shows the orientation of the 100-lead lqfp package. a detailed mechanical description is given in the mechanical ch aracteristics section of the full datasheet. figure 4-1. 100-lead lqfp outline (top view) 125 26 50 51 75 76 100
9 6042e?atarm?14-dec-06 at91sam7a3 preliminary 4.2 pinout table 4-1. pinout in 100-lead lqfp package 1 gnd 26 vddbu 51 pa20 76 pllrc 2 nrst 27 fwkup 52 pa21 77 vddana 3 tst 28 wkup0 53 pa22 78 advrefp 4 pb13 29 wkup1 54 pa23 79 gnd 5 pb12 30 shdw 55 pa24 80 pb14/adc0_ad0 6 pb11 31 gnd 56 pa25 81 pb15/adc0_ad1 7 pb10 32 pa4 57 pa26 82 pb16/adc0_ad2 8 pb9 33 pa5 58 pa27 83 pb17/adc0_ad3 9 pb8 34 pa6 59 vdd1v8 84 pb18/adc0_ad4 10 pb7 35 pa7 60 gnd 85 pb19/adc0_ad5 11 pb6 36 pa8 61 vdd3v3 86 pb20/adc0_ad6 12 pb5 37 pa9 62 pa28 87 pb21/adc0_ad7 13 pb4 38 vdd3v3 63 pa29 88 vdd3v3 14 pb3 39 gnd 64 pa30 89 pb22/adc1_ad0 15 vdd3v3 40 vdd1v8 65 pa31 90 pb23/adc1_ad1 16 gnd 41 pa10 66 jtagsel 91 pb24/adc1_ad2 17 vdd1v8 42 pa11 67 tdi 92 pb25/adc1_ad3 18 pb2 43 pa12 68 tms 93 pb26/adc1_ad4 19 pb1 44 pa13 69 tck 94 pb27/adc1_ad5 20 pb0 45 pa14 70 tdo 95 pb28/adc1_ad6 21 pa0 46 pa15 71 gnd 96 pb29/adc1_ad7 22 pa1 47 pa16 72 vddpll 97 ddm 23 pa2 48 pa17 73 xout 98 ddp 24 pa3 49 pa18 74 xin 99 vdd1v8 25 gnd 50 pa19 75 gnd 100 vdd3v3
10 6042e?atarm?14-dec-06 at91sam7a3 preliminary 5. power considerations 5.1 power supplies the at91sam7a3 has five types of power supply pins: vdd3v3 pins. they power the voltage regulator, the i/o lines, the flash and the usb transceivers; voltage ranges from 3.0v to 3.6v, 3.3v nominal. vdd1v8 pins. they are the outputs of the 1.8v voltage regulator and they power the logic of the device. vddpll pin. it powers the pll; voltage ranges from 1.65v to 1.95v, 1.8v typical. they can be connected to the vdd1v8 pin with decoupling capacitor. vddbu pin. it powers the slow clock oscillato r and the real time clock, as well as a part of the system controller; ranges from 3.0v and 3.6v, 3.3v nominal. vddana pin. it powers the adc; ranges from 3.0v and 3.6v, 3.3v nominal. no separate ground pins are provided for the different power supplies. only gnd pins are pro- vided and should be connected as shortly as possible to the system ground plane. 5.2 voltage regulator the at91sam7a3 embeds a voltage regulator that consumes less than 120 a static current and draws up to 130 ma of output current. adequate output supply decoupling is mandatory for vdd1v8 (pin 99)to reduce ripple and avoid oscillations. the best way to achieve this is to use two capacitors in para llel: one exter- nal 470 pf (or 1 nf) npo capacitor must be connected between vdd1v8 and gnd as close to the chip as possible. one external 3.3 f (or 4.7 f) x7r capacitor must be connected between vdd1v8 and gnd. all other vdd1v8 pins must be externally connected and have a proper decoupling capacitor (at least 100 nf). adequate input supply decoupling is mandatory for vdd3v3 (pin 100) in order to improve star- tup stability and reduce source vo ltage drop. the input decoupling capacitor should be placed close to the chip. for example, two capacitors can be used in parallel: 100 nf npo and 4.7 f x7r. all other vdd3v3 pins must be externally connected and have a proper decoupling capacitor (at least 100 nf).
11 6042e?atarm?14-dec-06 at91sam7a3 preliminary 5.3 typical powe ring schematics 5.3.1 3.3v single supply the at91sam7a3 supports a 3.3v single supply mode. the internal regulator is connected to the 3.3v source and its output feeds vddpll. figure 5-1 shows the power schematics to be used for usb bus-powered systems. figure 5-1. 3.3v system single power supply schematics usb connector up to 5.5v 3.3v vdd3v3 voltage regulator vdd1v8 vddana dc/dc converter vddpll vddbu
12 6042e?atarm?14-dec-06 at91sam7a3 preliminary 6. i/o lines considerations 6.1 jtag port pins tms, tdi and tck are schmitt trigger inputs. tm s and tck are 5v-tolerant, tdi is not. tms, tdi and tck do not integrate any resistors and have to be pulled-up externally. tdo is an output, driven at up to vdd3v3. the jtagsel pin is used to select the jtag boundary scan when asserted at a high level. the jtagsel pin integrates a permanent pull-down resistor so that it can be left unconnected for normal operations. 6.2 test pin the tst pin is used for manufacturing tests and integrates a pull-down resistor so that it can be left unconnected for normal operations. driving this line at a high level leads to unpredict- able results. 6.3 reset pin the nrst pin is bidirectional. it is handled by the on-chip reset controller and can be driven low to provide a reset signal to the external components or asserted low externally to reset the microcontroller. there is no constraint on the length of the reset pulse, and the reset controller can guarantee a minimum pulse length. this allows connection of a simple push-button on the nrst pin as system user reset, and the use of the nrst signal to reset all the components of the system. 6.4 pio controller a and b lines all the i/o lines pa0 to pa31 and pb0 to pb29 are 5v-tolerant and all integrate a programma- ble pull-up resistor. programming of this pull-up resistor is performed independently for each i/o line through the pio controllers. 5v-tolerant means that the i/o lines can drive voltage level according to vdd3v3, but can be driven with a voltage at up to 5.5v. however, driving an i/o line with a voltage over vdd3v3 while the programmable pull-up resistor is enabled creates a current path through the pull-up resistor from the i/o line to vddio. care should be taken, especially at reset, as all the i/o lines default as inputs with pull-up resistor enabled at reset. 6.5 shutdown logic pins the shdw pin is an open drain output. it can be tied to vddbu with an external pull-up resistor. the fwup, wkup0 and wkup1 pins are input-on ly. they can accept voltages only between 0v and vddbu. it is recommended to tie these pi ns either to gnd or to vddbu with an exter- nal resistor. 6.6 i/o line drive levels all the i/o lines can draw up to 2 ma.
13 6042e?atarm?14-dec-06 at91sam7a3 preliminary 7. processor and architecture 7.1 arm7tdmi processor risc processor based on armv4t von neumann architecture ? runs at up to 60 mhz, providing 0.9 mips/mhz two instruction sets ? arm high-performance 32-bit instruction set ? thumb high code density 16-bit instruction set three-stage pipeline architecture ? instruction fetch (f) ? instruction decode (d) ? execute (e) 7.2 debug and test features integrated embeddedice ? (embedded in-circuit emulator) ? two watchpoint units ? test access port accessible through a jtag protocol ? debug communication channel debug unit ?two-pin uart ? debug communication channel interrupt handling ? chip id register ieee1149.1 jtag boundary-scan on all digital pins 7.3 memory controller bus arbiter ? handles requests from the arm7tdmi and the peripheral data controller address decoder provides selection signals for ? three internal 1mbyte memory areas ? one 256 mbyte embedded peripheral area abort status registers ? source, type and all parameters of the access leading to an abort are saved ? facilitates debug by de tection of bad pointers misalignment detector ? alignment checking of all data accesses ? abort generation in case of misalignment remap command ? remaps the internal sram in place of the embedded non-volatile memory ? allows handling of dynamic exception vectors 16-area memory protection unit ? individually programmable size between 1k bytes and 1m bytes
14 6042e?atarm?14-dec-06 at91sam7a3 preliminary ? individually programmable protection against write and/or user access ? peripheral protection against write and/or user access embedded flash controller ? embedded flash interface, up to three programmable wait states ? read-optimized interface, buffering and anticipating the 16-bit requests, reducing the required wait states ? password-protected program, erase and lock/unlock sequencer ? automatic consecutive programming, erasing and locking operations ? interrupt generation in case of forbidden operation 7.4 peripheral dma controller handles data transfer between peripherals and memories nineteen channels ? two for each usart ? two for the debug unit ? two for each serial synchronous controller ? two for each serial peripheral interface ? one for the multimedia card interface ? one for each analog-to-digital converter low bus arbitration overhead ? one master clock cycle needed for a transfer from memory to peripheral ? two master clock cycles needed for a transfer from peripheral to memory next pointer management for reducing interrupt latency requirements
15 6042e?atarm?14-dec-06 at91sam7a3 preliminary 8. memory 8.1 embedded memories 256 kbytes of flash memory ? 1024 pages of 256 bytes. ? fast access time, 30 mhz single cycl e access in worst case conditions. ? page programming time: 6 ms, including page auto-erase ? full erase time: 15 ms ? 10,000 write cycles, 10-yea r data retent ion capability ? 16 lock bits, each protecting 16 pages 32 kbytes of fast sram ? single-cycle access at full speed
16 6042e?atarm?14-dec-06 at91sam7a3 preliminary figure 8-1. at91sam7a3 memory mapping 0x1000 0000 0x0000 0000 0x0fff ffff 0xf000 0000 0xefff ffff 0xffff ffff 256 mbytes 256 mbytes 14 x 256 mbytes 3,584 mbytes 0x000f fff 0x0010 0000 0x001f fff 0x0020 0000 0x002f fff 0x0030 0000 0x0000 0000 1 mbytes 1 mbytes 1 mbytes 252 mbytes 0xfffa 0000 0xfffa 3fff 0xfffa c000 0xf000 0000 0xfffb 8000 0xfffc 0000 0xfffc 3fff 0xfffc 4000 0xfffc 7fff 0xfffd 4000 0xfffd 7fff 0xfffd 3fff 0xfffd ffff 0xfffe 0000 0xfffe 3fff 0xffff efff 0xffff ffff 0xffff f000 0xfffe 4000 0xfffe 8000 0xfffe 7fff 0xfffb 4000 0xfffb 7fff 0xfff7 ffff 0xfff8 8000 0xfff9 ffff 0xfffc ffff 0xfffd 8000 0xfffd bfff 0xfffc bfff 0xfffc c000 0xfffb ffff 0xfffb c000 0xfffb bfff 0xfffa ffff 0xfffb 0000 0xfffb 3fff 0xfffd 0000 0xfffd c000 0xfffc 8000 16 kbytes 16 kbytes 16 kbytes 16 kbytes 16 kbytes 16 kbytes 16 kbytes 0xfffa 4000 0xfffa 7fff 16 kbytes 0xfffa 8000 0xfffa bfff 16 kbytes 16 kbytes 0xfff8 0000 0xfff8 3fff 16 kbytes 0xfff8 4000 0xfff8 7fff 16 kbytes 16 kbytes 16 kbytes 16 kbytes 16 kbytes 16 kbytes 16 kbytes 0x0fff ffff 512 bytes/128 registers 512 bytes/128 registers 256 bytes/64 registers 16 bytes/4 registers 16 bytes/4 registers 16 bytes/4 registers 16 bytes/4 registers 8 bytes/2 registers 256 bytes/64 registers 512 bytes/128 registers 512 bytes/128 registers 0xffff f000 0xffff f200 0xffff f1ff 0xffff f3ff 0xffff fbff 0xffff fcff 0xffff feff 0xffff ffff 0xffff f400 0xffff fc00 0xffff fd0f 0xffff fd1f 0xffff fc2f 0xffff fc3f 0xffff fd4f 0xffff fc58 0xffff f5ff 0xffff f600 0xffff f7ff 0xffff f800 0xffff fd00 0xffff fd10 0xffff ff00 0xffff fd20 0xffff fd30 0xffff fd40 0xffff fd50 0xffff fd59 general purpose backup registers internal memories undefined (abort) flash before remap sram after remap internal flash internal sram reserved address memory space internal memory mapping tc0, tc1, tc2 tc3, tc4, tc5 tc6, tc7, tc8 can0 can1 usart0 usart1 usart2 pwmc mci reserved reserved shdwc reserved ssc0 adc1 reserved reserved twi ssc1 spi0 spi1 udp adc0 aic dbgu pioa reserved pmc mc wdt gpbr pit rtt rstc piob peripheral mapping system controller mapping internal peripherals reserved sysc
17 6042e?atarm?14-dec-06 at91sam7a3 preliminary 8.2 memory mapping 8.2.1 internal sram the at91sam7a3 embeds a high-speed 32-kbyte sram bank. after reset and until the remap command is performed, the sram is only accessible at address 0x0020 0000. after remap, the sram also becomes available at address 0x0. 8.2.2 internal flash the at91sam7a3 features one bank of 256 kbytes of flash. the flash is mapped to address 0x0010 0000. it is also accessible at address 0x0 after the reset and before the remap command. figure 8-2. internal memory mapping 8.3 embedded flash 8.3.1 flash overview the flash block of the at91sam7a3 is organized in 1024 pages of 256 bytes. it reads as 65,536 32-bit words. the flash block contains a 256-byte write bu ffer, accessible through a 32-bit interface. when flash is not used (read or write access), it is automatically put into standby mode. 8.3.2 embedded flash controller the embedded flash controller (efc) manages accesses performed by the masters of the system. it enables reading the flash and writing the write buffer. it also contains a user inter- face mapped within the me mory controller on the apb. th e user interf ace allows: programming of the access parameters of the flash (number of wait states, timings, etc.) starting commands such as full erase, page erase, page program, nvm bit set, nvm bit clear, etc. getting the end status of the last command getting error status programming interrupts on the end of the last commands or on errors 256m bytes flash before remap sram after remap undefined areas (abort) 0x000f ffff 0x001f ffff 0x002f ffff 0x0fff ffff 1m bytes 1m bytes 1m bytes 253m bytes internal flash internal sram 0x0000 0000 0x0010 0000 0x0020 0000 0x0030 0000
18 6042e?atarm?14-dec-06 at91sam7a3 preliminary the embedded flash controller also provides a dual 32-bit prefetch buffer that optimizes 16- bit access to the flash. this is particularly efficient when the proces sor is running in thumb mode. 8.3.3 lock regions the embedded flash controller manages 16 lock bits to protect 16 regions of the flash against inadvertent flash erasing or programming commands. the at91sam7a3 has 16 lock regions. each lock region contains 16 pages of 256 bytes. each lock region has a size of 4 kbytes, thus only the first 64 kbytes can be locked. the 16 nvm bits are software programmable through the efc user interface. the command ?set lock bit? activates the protection. the command ?clear lock bit? unlocks the lock region.
19 6042e?atarm?14-dec-06 at91sam7a3 preliminary 9. system controller the system controller manages all vital blocks of the microcontroller: interrupts, clocks, power, time, debug and reset. the system controller peripherals are all mapped to the highest 4k bytes of address space, between addresses 0xffff f000 and 0xffff ffff. each peripheral has an address space of up to 512 bytes, representing up to 128 registers. figure 9-1 on page 20 shows the system controller block diagram. figure 8-1 on page 16 shows the mapping of the user interface of the system controller peripherals. note that the memory controller configuration user interface is also mapped within this address space.
20 6042e?atarm?14-dec-06 at91sam7a3 preliminary figure 9-1. system controller block diagram 9.1 system controller mapping nrst slck advanced interrupt controller periodic interval timer pa0-pa31 system controller watchdog timer pios controller power management controller pit_irq mck wdt_irq periph_irq{2..3] periph_nreset periph_clk[2..27] pck mck pmc_irq udpck nirq nfiq embedded peripherals periph_clk[2..3] pck[0-3] in out enable arm7tdmi slck fiq irq0-irq1-irq2-irq3 fiq periph_irq[4..26] periph_irq[2..27] int int periph_nreset periph_clk[4..26] ice_nreset proc_nreset periph_nreset dbgu_txd dbgu_rxd pit_irq rtt_irq dbgu_irq pmc_irq wdt_irq rstc_irq boundary scan tap controller jtag_nreset debug pck debug idle debug memory controller mck proc_nreset proc_nreset proc_nreset periph_nreset idle debug unit dbgu_irq mck dbgu_rxd periph_nreset dbgu_txd usb device port embedded flash udpck periph_nreset periph_clk[27] periph_irq[27] wkup1 shdw real-time timer reset controller periph_nreset wdt_fault wdrproc vdd1v8 por proc_nreset rtt_irq slck flash_poe jtag_nreset rstc_irq slck periph_nreset shutdown controller vddbu por rcosc vddbu powered 4 general-purpose backup regs main osc xin xout mainck pll pllrc pllck pb0-pb29 vdd1v8 powered wdt_fault wdrproc irq0-irq1-irq2-irq3 vdd3v3 por wkup0 fwkup ice_nreset
21 6042e?atarm?14-dec-06 at91sam7a3 preliminary 9.2 reset controller the reset controller is based on three power-on reset cells. it gives the status of the last reset, indicating whether it is a general reset, a wake-up reset, a software reset, a user reset or a watchdog reset. in addition, it controls the internal resets and the nrst pin output. it shapes a signal on the nrst line, guaranteeing that the length of the pulse meets any requirement. 9.3 clock generator the clock generator embe ds one low-power rc oscillator, one main oscillator and one pll with the following characteristics: ? rc oscillator ranges betw een 22 khz and 42 khz ? main oscillator frequency ranges between 3 and 20 mhz ? main oscillator can be bypassed ? pll output ranges between 80 and 220 mhz it provides slck, mainck and pllck. figure 9-2. clock generator block diagram 9.4 power management controller the power management controller uses the clock generator outputs to provide: ? the processor clock pck ? the master clock mck ? the usb clock udpck ? all the peripheral clocks, independently controllable ? four programmable clock outputs the master clock (mck) is programmable from a few hundred hz to the maximum operating frequency of the device. the processor clock (pck) switches off when ente ring processor idle mode, thereby reducing power consumption while waiting an interrupt. power management controller xin xout pllrc slow clock slck main clock mainck pll clock pllck control status embedded rc oscillator main oscillator pll and divider clock generator
22 6042e?atarm?14-dec-06 at91sam7a3 preliminary figure 9-3. power management controller block diagram 9.5 advanced interrupt controller controls the interrupt lines (nirq and nfiq) of the arm processor individually maskable and vectored interrupt sources ? source 0 is reserved for the fast interrupt input (fiq) ? source 1 is reserved for system peripherals (st, pmc, dbgu, etc.) ? other sources control the peripheral interrupts or external interrupts ? programmable edge-triggered or level-sensitive internal sources ? programmable positive/negative edge-triggered or high/low level-sensitive external sources (fiq, irq) 8-level priority controller ? drives the normal interrupt nirq of the processor ? handles priority of the interrupt sources ? higher priority interrupts can be served during service of a lower priority interrupt vectoring ? optimizes interrupt service routine branch and execution ? one 32-bit vector register per interrupt source ? interrupt vector register reads the corresponding current interrupt vector protect mode ? easy debugging by preventing automatic operations fast forcing ? permits redirecting any interrupt source on the fast interrupt general interrupt mask ? provides processor synchronization on events without triggering an interrupt mck periph_clk[2..26] int udpck slck mainck pllck prescaler /1,/2,/4,...,/64 pck processor clock controller idle mode master clock controller peripherals clock controller on/off usb clock controller on/off slck mainck pllck prescaler /1,/2,/4,...,/64 programmable clock controller pllck divider /1,/2,/4 pck[0..3]
23 6042e?atarm?14-dec-06 at91sam7a3 preliminary 9.6 debug unit comprises ? one two-pin uart ? one interface for the debug communication channel (dcc) support ? one set of chip id registers ? one interface allowing ice access prevention two-pin uart ? usart-compatible user interface ? programmable baud rate generator ? parity, framing and overrun error ? automatic echo, local loopback and remote loopback channel modes debug communication channel support ? offers visibility of commrx and commt x signals from the arm processor chip id registers ? identification of the device revision, sizes of the embedded memories, set of peripherals ? chip id is 0x260a0941 (version 1) 9.7 period interval timer 20-bit programmable counter plus 12-bit interval counter 9.8 watchdog timer 12-bit key-protected programmable counter running on prescaled slck provides reset or interrupt signals to the system counter may be stopped while the processor is in debug state or in idle mode 9.9 real-time timer 32-bit free-running counter with alarm programmable 16-bit prescaler for sclk accuracy compensation 9.10 shutdown controller software programmable assertion of the shdw open-drain pin de-assertion programmable with the pins wkup0, wkup1 and fwkup 9.11 pio controllers a and b the pio controllers a and b respectively control 32 and 30 programmable i/o lines fully programmable through set/clear registers multiplexing of two peripheral functions per i/o line for each i/o line (whether assigned to a peripheral or used as general purpose i/o) ? input change interrupt ? half a clock period glitch filter ? multi-drive option enables driving in open drain
24 6042e?atarm?14-dec-06 at91sam7a3 preliminary ? programmable pull up on each i/o line ? pin data status register, supplies visib ility of the level on the pin at any time synchronous output, provides set and clear of several i/o lines in a single write
25 6042e?atarm?14-dec-06 at91sam7a3 preliminary 10. peripherals 10.1 peripheral mapping each user peripheral is allocated 16k bytes of address space. figure 10-1. user peripherals mapping 16k bytes peripheral name peripheral address size 16k bytes 16k bytes 16k bytes 0xfffa 0000 0xfffa 3fff tc0, tc1, tc2 timer/counter 0, 1 and 2 16k bytes 16k bytes 16k bytes 16k bytes reserved reserved 0xfffa 4000 0xfffa 7fff tc3, tc4, tc5 timer/counter 3, 4 and 5 0xf000 0000 twi two-wire interface 0xfffb 8000 usart0 universal synchronous asynchronous receiver transmitter 0 0xfffc 0000 0xfffc 3fff usart1 universal synchronous asynchronous receiver transmitter 1 0xfffc 4000 0xfffc 7fff ssc0 serial synchronous controller 0 0xfffd 0000 0xfffd 3fff ssc1 serial synchronous controller 1 0xfffd 4000 0xfffd 7fff 0xfffd ffff spi0 serial peripheral interface 0 0xfffe 0000 0xfffe 3fff reserved 0xfffe ffff 0xfffe 8000 0xfffb 4000 0xfffb 7fff 16k bytes 0xfffa 8000 0xfffa bfff tc6, tc7, tc8 timer/counter 6, 7 and 8 16k bytes 0xfff8 0000 0xfff8 3fff can0 can controller 0 16k bytes 0xfff8 4000 0xfff8 7fff can1 can controller 1 reserved 0xfff8 8000 0xfff9 ffff 16k bytes 0xfffc ffff 16k bytes spi1 serial peripheral interface 1 0xfffe 4000 0xfffe 7fff 0xfff7 ffff 0xfffd 8000 0xfffd bfff adc0 analog-to-digital converter 0 16k bytes usart2 universal synchronous asynchronous receiver transmitter 1 0xfffc 8000 0xfffc bfff 0xfffc c000 0xfffb ffff reserved 0xfffb c000 0xfffb bfff 0xfffd c000 adc1 analog-to-digital converter 1 16k bytes pwmc 16k bytes 0xfffa c000 0xfffa ffff mci multimedia card interface 0xfffb 0000 0xfffb 3fff udp usb device port 16k bytes 16k bytes pwm controller
26 6042e?atarm?14-dec-06 at91sam7a3 preliminary 10.2 peripheral multiplexing on pio lines the at91sam7a3 features two pio controllers, pioa and piob, which multiplex the i/o lines of the peripheral set. pio controllers a and b control respectively 32 and 30 lines. each line can be assigned to one of two peripheral functions, a or b. some of them can also be multiplexed with analog input of both adc controllers. table 10-1 on page 27 and table 10-2 on page 28 define how the i/o lines of the peripherals a, b or analog input are multiplexed on the pio controllers a and b. the two columns ?func- tion? and ?comments? have been inserted for the user?s own comments; they may be used to track how pins are defined in an application. note that some peripheral functions that are output only may be duplicated within both tables. at reset, all i/o lines are automatically c onfigured as input with the programmable pull-up enabled, so that the device is maintained in a static state as soon as a reset occurs.
27 6042e?atarm?14-dec-06 at91sam7a3 preliminary 10.3 pio controller a multiplexing table 10-1. multiplexing on pio controller a pio controller a application usage i/o line peripheral a peripheral b comment function comments pa0 twd adc0_adtrg pa1 twck adc1_adtrg pa 2 r x d 0 pa 3 t x d 0 pa4 sck0 spi1_npsc0 pa5 rts0 spi1_npcs1 pa6 cts0 spi1_npcs2 pa7 rxd1 spi1_npcs3 pa8 txd1 spi1_miso pa9 rxd2 spi1_mosi pa10 txd2 spi1_spck pa11 spi0_npcs0 pa12 spi0_npcs1 mcda1 pa13 spi0_npcs2 mcda2 pa14 spi0_npcs3 mcda3 pa15 spi0_miso mcda0 pa16 spi0_mosi mccda pa17 spi0_spck mcck pa18 pwm0 pck0 pa19 pwm1 pck1 pa20 pwm2 pck2 pa21 pwm3 pck3 pa 2 2 p w m 4 i r q 0 pa 2 3 p w m 5 i r q 1 pa 2 4 p w m 6 t c l k 4 pa 2 5 p w m 7 t c l k 5 pa26 canrx0 pa27 cantx0 pa28 canrx1 tclk3 pa29 cantx1 tclk6 pa30 drxd tclk7 pa 3 1 d t x d t c l k 8
28 6042e?atarm?14-dec-06 at91sam7a3 preliminary 10.4 pio controller b multiplexing table 10-2. multiplexing on pio controller b pio controller b application usage i/o line peripheral a peripheral b comment function comments pb0 irq2 pwm5 pb1 irq3 pwm6 pb2 tf0 pwm7 pb3 tk0 pck0 pb4 td0 pck1 pb5 rd0 pck2 pb6 rk0 pck3 pb7 rf0 cantx1 pb8 fiq tf1 pb9 tclk0 tk1 pb10 tclk1 rk1 pb11 tclk2 rf1 pb12 tioa0 td1 pb13 tiob0 rd1 pb14 tioa1 pwm0 adc0_ad0 pb15 tiob1 pwm1 adc0_ad1 pb16 tioa2 pwm2 adc0_ad2 pb17 tiob2 pwm3 adc0_ad3 pb18 tioa3 pwm4 adc0_ad4 pb19 tiob3 spi1_npcs1 adc0_ad5 pb20 tioa4 spi1_npcs2 adc0_ad6 pb21 tiob4 spi1_npcs3 adc0_ad7 pb22 tioa5 adc1_ad0 pb23 tiob5 adc1_ad1 pb24 tioa6 rts1 adc1_ad2 pb25 tiob6 cts1 adc1_ad3 pb26 tioa7 sck1 adc1_ad4 pb27 tiob7 rts2 adc1_ad5 pb28 tioa8 cts2 adc1_ad6 pb29 tiob8 sck2 adc1_ad7
29 6042e?atarm?14-dec-06 at91sam7a3 preliminary 11. peripheral identifiers the at91sam7a3 embeds a wide range of peripherals. table 11-1 defines the peripheral identifiers of the at91sam7a3. unique peripheral identifiers are defined for both the aic and the pmc. note: 1. setting sysc and adc bits in the clock se t/clear registers of t he pmc has no effect. the system controller and adc are continuously clocked. table 11-1. peripheral identifiers peripheral id peripheral mnemonic peripheral name external interrupt 0 aic advanced interrupt controller fiq 1 sysc (1) 2 pioa parallel i/o controller a 3 piob parallel i/o controller b 4 can0 can controller 0 5 can1 can controller 1 6 us0 usart 0 7 us1 usart 1 8 us2 usart 2 9 mci multimedia card interface 10 twi two-wire interface 11 spi0 serial peripheral interface 0 12 spi1 serial peripheral interface 1 13 ssc0 synchronous serial controller 0 14 ssc1 synchronous serial controller 1 15 tc0 timer/counter 0 16 tc1 timer/counter 1 17 tc2 timer/counter 2 18 tc3 timer/counter 3 19 tc4 timer/counter 4 20 tc5 timer/counter 5 21 tc6 timer/counter 6 22 tc7 timer/counter 7 23 tc8 timer/counter 8 24 adc0 (1) analog-to digital converter 0 25 adc1 (1) analog-to digital converter 1 26 pwmc pwm controller 27 udp usb device port 28 aic advanced interrupt controller irq0 29 aic advanced interrupt controller irq1 30 aic advanced interrupt controller irq2 31 aic advanced interrupt controller irq3
30 6042e?atarm?14-dec-06 at91sam7a3 preliminary 11.1 serial peripheral interface supports communication with external serial devices ? four chip selects with external dec oder allow communication with up to 15 peripherals ? serial memories, such as dataflash ? and 3-wire eeproms ? serial peripherals, such as adcs, dacs, lcd controllers, can controllers and sensors ? external co-processors master or slave serial peripheral bus interface ? 8- to 16-bit programmable data length per chip select ? programmable phase and polarity per chip select ? programmable transfer delays per chip select between consecutive transfers and between clock and data ? programmable delay between consecutive transfers ? selectable mode fault detection ? maximum frequency at up to master clock 11.2 two-wire interface master mode only compatibility with standard two-wire serial memories one, two or three bytes for slave address sequential read/write operations 11.3 usart programmable baud rate generator 5- to 9-bit full-duplex synchronous or asynchronous serial communications ? 1, 1.5 or 2 stop bits in asynchronous mode or 1 or 2 stop bits in synchronous mode ? parity generation and error detection ? framing error detection, overrun error detection ? msb- or lsb-first ? optional break generation and detection ? by 8 or by 16 over-sampling receiver frequency ? hardware handshaking rts-cts ? receiver time-out and transmitter timeguard ? optional multi-drop mode with address generation and detection rs485 with driver control signal iso7816, t = 0 or t = 1 protocols for interfacing with smart cards ? nack handling, error counter with repetition and iteration limit irda modulation and demodulation ? communication at up to 115.2 kbps test modes
31 6042e?atarm?14-dec-06 at91sam7a3 preliminary ? remote loopback, local loopback, automatic echo 11.4 serial synchronous controller provides serial synchronous communication links used in audio and telecom applications contains an independent receiver and transmitter and a common clock divider offers a configurable frame sync and data length receiver and transmitter can be programmed to start automatically or on detection of different event on the frame sync signal receiver and transmitter include a data signal , a clock signal and a frame synchronization signal 11.5 timer counter three 16-bit timer counter channels wide range of functions including: ? frequency measurement ? event counting ? interval measurement ? pulse generation ?delay timing ? pulse width modulation ? up/down capabilities each channel is user-configurable and contains: ? three external clock inputs ? five internal clock inputs as defined in table 11-2 . ? two multi-purpose input/output signals ? two global registers that act on all three tc channels 11.6 pwm controller eight channels, one 20-bit counter per channel common clock generator, providing thirteen different clocks ? a modulo n counter providing eleven clocks ? two independent linear dividers working on modulo n counter outputs independent channel programming table 11-2. timer counter clock assignment tc clock input clock timer_clock1 mck/2 timer_clock2 mck/8 timer_clock3 mck/32 timer_clock4 mck/128 timer_clock5 mck/1024
32 6042e?atarm?14-dec-06 at91sam7a3 preliminary ? independent enable/disable commands ? independent clock selection ? independent period and duty cycle, with double buffering ? programmable selection of the output waveform polarity ? programmable center or left aligned output waveform 11.7 usb device port usb v2.0 full-speed compliant,12 mbits per second. embedded usb v2.0 full-speed transceiver six endpoints ? endpoint 0: 8 bytes ? endpoint 1 and 2: 64 bytes ping-pong ? endpoint 3: 64 bytes ? endpoint 4 and 5: 512 bytes ping-pong embedded 2,376-byte dual-port ram for endpoints ? ping-pong mode (two memory banks) for bulk endpoints suspend/resume logic 11.8 multimedia card interface compatibility with multimedia ca rd specification version 2.2 compatibility with sd memory ca rd specification version 1.0 cards clock rate up to master clock divided by 2 embeds power management to slow down clock rate when not used supports up to sixteen slots (through multiplexing) ? one slot for one multimedia card bus (up to 30 cards) or one sd memory card supports stream, block and multi-block data read and write supports connection to peripheral data controller ? minimizes processor intervention for large buffer transfers 11.9 can controller fully compliant with can 2.0b active controllers bit rates up to 1mbit/s 16 object-oriented mailboxes, each with the following properties: ? can specification 2.0 part a or 2.0 part b programmable for each message ? object-configurable as receive (with overwrite or not) or transmit ? local tag and mask filters up to 29-bit identifier/channel ? 32-bit access to data register s for each mailbox data object ? uses a 16-bit time stamp on receive and transmit messages ? hardware concatenation of id unmasked bit fields to speed up family id processing ? 16-bit internal timer for time stamping and network synchronization
33 6042e?atarm?14-dec-06 at91sam7a3 preliminary ? programmable reception buffer length up to 16 mailbox object ? priority management between transmission mailboxes ? autobaud and listening mode ? low power mode and programmable wake-up on bus activity or by the application ? data, remote, error and overload frame handling 11.10 analog-to-digital converter 8-channel adc 10-bit 384k, or 8-bit 533k, samples/sec successive approximation register adc -3/+3 lsb integral non linearity, -2/+2 lsb differential non linearity integrated 8-to-1 multiplexer, offering eight independent 3.3v analog inputs individual enable and disable of each channel external voltage reference for better accuracy on low-voltage inputs multiple trigger sources ? hardware or software trigger ? external pins: adtrg0 and adtrg1 ? timer counter 0 to 5 outputs: tioa0 to tioa5 sleep mode and conversion sequencer ? automatic wakeup on trigger and back to sleep mode after conversions of all enabled channels all analog inputs are shar ed with digital signals
34 6042e?atarm?14-dec-06 at91sam7a3 preliminary
35 6042e?atarm?14-dec-06 at91sam7a3 preliminary 12. arm7tdmi processor 12.1 overview the arm7tdmi core executes both the 32-bit arm and 16-bit thumb instruction sets, allow- ing the user to trade off between high performance and high code density. the arm7tdmi processor implements von neuman architecture , using a three-stage pipeline consisting of fetch, decode, and execute stages. the main features of the arm7tdmi processor are: arm7tdmi based on armv4t architecture two instruction sets ? arm high-performance 32-bit instruction set ? thumb high code density 16-bit instruction set three-stage pipeline architecture ? instruction fetch (f) ? instruction decode (d) ? execute (e) 12.2 arm7tdmi processor for further details on arm7tdmi, refer to the following arm documents: arm architecture reference manual (ddi 0100e) arm7tdmi technical reference manual (ddi 0210b) 12.2.1 instruction type instructions are either 32 bits long (in arm state) or 16 bits long (in thumb state). 12.2.2 data type arm7tdmi supports byte (8-bit), half-word (16-bit) and word (32-bit) data types. words must be aligned to four-byte boundaries and half words to two-byte boundaries. unaligned data access behavior depends on which instruction is used where. 12.2.3 arm7tdmi operating mode the arm7tdmi, based on arm architecture v4t, supports seven processor modes: user : the normal arm program execution state fiq : designed to support high-speed data transfer or channel process irq : used for general-purpose interrupt handling supervisor : protected mode for the operating system abort mode : implements virtual memory and/or memory protection system : a privileged user mode for the operating system undefined : supports software emulation of hardware coprocessors mode changes may be made under software control, or may be brought about by external interrupts or exception processing. most application programs execute in user mode. the
36 6042e?atarm?14-dec-06 at91sam7a3 preliminary non-user modes, or privileged modes, are entered in order to service interrupts or exceptions, or to access protected resources. 12.2.4 arm7tdmi registers the arm7tdmi processor has a total of 37 registers: 31 general-purpose 32-bit registers 6 status registers these registers are not accessible at the same time. the processor state and operating mode determine which registers are available to the programmer. at any one time 16 registers are visible to the user. the remainder are synonyms used to speed up exception processing. register 15 is the program counter (pc) and can be used in all instructions to reference data relative to the current instruction. r14 holds the return address after a subroutine call. r13 is used (by software convention) as a stack pointer table 12-1. arm7tdmi arm modes and registers layout user and system mode supervisor mode abort mode undefined mode interrupt mode fast interrupt mode r0 r0 r0 r0 r0 r0 r1 r1 r1 r1 r1 r1 r2 r2 r2 r2 r2 r2 r3 r3 r3 r3 r3 r3 r4 r4 r4 r4 r4 r4 r5 r5 r5 r5 r5 r5 r6 r6 r6 r6 r6 r6 r7 r7 r7 r7 r7 r7 r8 r8 r8 r8 r8 r8_fiq r9 r9 r9 r9 r9 r9_fiq r10 r10 r10 r10 r10 r10_fiq r11 r11 r11 r11 r11 r11_fiq r12 r12 r12 r12 r12 r12_fiq r13 r13_svc r13_abort r13_undef r13_irq r13_fiq r14 r14_svc r14_abort r14_undef r14_irq r14_fiq pc pc pc pc pc pc cpsr cpsr cpsr cpsr cpsr cpsr spsr_svc spsr_abort spsr_undef spsr_irq spsr_fiq mode-specific banked registers
37 6042e?atarm?14-dec-06 at91sam7a3 preliminary registers r0 to r7 are unbanked registers. this means that each of them refers to the same 32-bit physical register in all processor modes. they are general-purpose registers, with no special uses managed by the architecture, and can be used wherever an instruction allows a general-purpose register to be specified. registers r8 to r14 are banked registers. this means that each of them depends on the cur- rent mode of the processor. 12.2.4.1 modes and exception handling all exceptions have banked registers for r14 and r13. after an exception, r14 holds the return addr ess for exception processing. this address is used to return after the exception is processed, as well as to address the instruction that caused the exception. r13 is banked across exception modes to provide each exception handler with a private stack pointer. the fast interrupt mode also banks registers 8 to 12 so that interrupt processing can begin without having to save these registers. a seventh processing mode, system mode, does not have any banked registers. it uses the user mode registers. system mode runs tasks that require a privileged processor mode and allows them to invoke all classes of exceptions. 12.2.4.2 status registers all other processor states are held in status re gisters. the current operating processor status is in the current program status register (cpsr). the cpsr holds: four alu flags (negative, zero, carry, and overflow) two interrupt disable bits (one for each type of interrupt) one bit to indicate arm or thumb execution five bits to encode the current processor mode all five exception modes also have a saved prog ram status register (spsr) that holds the cpsr of the task immediately preceding the exception. 12.2.4.3 exception types the arm7tdmi supports five types of exception and a privileged processing mode for each type. the types of exceptions are: fast interrupt (fiq) normal interrupt (irq) memory aborts (used to implement memory protection or virtual memory) attempted execution of an undefined instruction software interrupts (swis) exceptions are generated by internal and external sources. more than one exception can occur in the same time. when an exception occurs, th e banked version of r14 and th e spsr for the exception mode are used to save state.
38 6042e?atarm?14-dec-06 at91sam7a3 preliminary to return after handlin g the exception, the spsr is moved to the cpsr , and r14 is moved to the pc. this can be done in two ways: by using a data-processing instruction with the s-bit set, and the pc as the destination by using the load multiple with restore cpsr instruction (ldm)
39 6042e?atarm?14-dec-06 at91sam7a3 preliminary 12.2.5 arm instruction set overview the arm instruction set is divided into: branch instructions data processing instructions status register transfer instructions load and store instructions coprocessor instructions exception-generating instructions arm instructions can be executed conditionally. every instruction contains a 4-bit condition code field (bit[31:28]). table 12-2 gives the arm instruction mnemonic list. table 12-2. arm instruction mnemonic list mnemonic operation mnemonic operation mov move cdp coprocessor data processing add add mvn move not sub subtract adc add with carry rsb reverse subtract sbc subtract with carry cmp compare rsc reverse subtract with carry tst test cmn compare negated and logical and teq test equivalence eor logical exclusive or bic bit clear mul multiply orr logical (inclusive) or smull sign long multiply mla multiply accumulate smlal signed long multiply accumulate umull unsigned long multiply msr move to status register umla l unsigned long multiply accumulate b branch mrs move from status register bx branch and exchange bl branch and link ldr load word swi software interrupt ldrsh load signed halfword str store word ldrsb load signed byte strh store half word ldrh load half word strb store byte ldrb load byte strbt store register byte with translation ldrbt load register byte with translati on strt store register with translation ldrt load register with translation stm store multiple ldm load multiple swpb swap byte swp swap word mrc move from coprocessor mcr move to coprocessor stc store from coprocessor ldc load to coprocessor
40 6042e?atarm?14-dec-06 at91sam7a3 preliminary 12.2.6 thumb instruction set overview the thumb instruction set is a re-encoded subset of the arm instruction set. the thumb instruction set is divided into: branch instructions data processing instructions load and store instructions load and store multiple instructions exception-generating instruction in thumb mode, eight general-purpose registers, r0 to r7, are available that are the same physical registers as r0 to r7 when executing arm instructions. some thumb instructions also access to the program counter (arm register 15), the link register (arm register 14) and the stack pointer (arm register 13). furthe r instructions allow limited access to the arm registers 8 to 15. table 12-3 gives the thumb instruction mnemonic list. table 12-3. thumb instruction mnemonic list mnemonic operation mnemonic operation mov move mvn move not add add adc add with carry sub subtract sbc subtract with carry cmp compare cmn compare negated tst test neg negate and logical and bic bit clear eor logical exclusive or orr logical (inclusive) or lsl logical shift left lsr logical shift right asr arithmetic shift right ror rotate right mul multiply b branch bl branch and link bx branch and exchange swi software interrupt ldr load word str store word ldrh load half word strh store half word ldrb load byte strb store byte ldrsh load signed halfword ldrsb load signed byte ldmia load multiple stmia store multiple push push register to stack pop pop register from stack
41 6042e?atarm?14-dec-06 at91sam7a3 preliminary 13. at91sam7a3 debug and test features 13.1 overview the at91sam7a3 features a number of complementary debug and test capabilities. a com- mon jtag/ice (embedded ice) port is used for standard debugging functions, such as downloading code and single-stepping through programs. the debug unit provides a two-pin uart that can be used to upload an application into internal sram. it manages the interrupt handling of the internal commtx and commrx signa ls that trace the activity of the debug communication channel. a set of dedicated debug and test input/output pins gives direct access to these capabilities from a pc-based test environment. 13.2 block diagram figure 13-1. debug and test block diagram ice pdc dbgu pio drxd dtxd tst tms tck tdi jtagsel tdo boundary ta p ice/jtag ta p arm7tdmi reset and test por
42 6042e?atarm?14-dec-06 at91sam7a3 preliminary 13.3 application examples 13.3.1 debug environment figure 13-2 on page 42 shows a complete debug environment example. the ice/jtag inter- face is used for standard debugging functions, such as downloading code and single-stepping through the program. figure 13-2. application debug environment example at91sam7a3-based application board ice/jtag interface host debugger ice/jtag connector at91sam7a3 terminal rs232 connector
43 6042e?atarm?14-dec-06 at91sam7a3 preliminary 13.4 test environment figure 13-3 on page 43 shows a test environment example. test vectors are sent and inter- preted by the tester. in this example, the ?board in test? is designed using a number of jtag- compliant devices. these devi ces can be connected to form a single scan chain. figure 13-3. application test environment example 13.5 debug and test pin description tester jtag interface ice/jtag connector at91sam7a3-based application board in test at91sam7a3 test adaptor chip 2 chip n chip 1 table 13-1. debug and test pin list pin name function type active level reset/test nrst microcontroller reset input/output low tst test mode select input high ice and jtag tck test clock input tdi test data in input tdo test data out output tms test mode select input jtagsel jtag selection input debug unit drxd debug receive data input dtxd debug transmit data output
44 6042e?atarm?14-dec-06 at91sam7a3 preliminary 13.6 functional description 13.6.1 test pin one dedicated pin, tst, is used to define the device operating mode. the user must make sure that this pin is tied at low level to ensure normal operating conditions. other values asso- ciated with this pin are reserved for manufacturing test. 13.6.2 embedded ice ? (embedded in-circuit emulator) the arm7tdmi embedded ice is supported via the ice/jtag port. the internal state of the arm7tdmi is examined through an ice/jtag port. the arm7tdmi processor contains hardware ex tensions for advanced debugging features: in halt mode, a store-multiple (stm) can be inserted into the instruction pipeline. this exports the contents of the arm7tdmi registers. this data can be serially shifted out without affecting the rest of the system. in monitor mode, the jtag interface is used to transfer data between the debugger and a simple monitor program running on the arm7tdmi processor. there are three scan chains inside the arm7tdmi processor that support testing, debugging, and programming of the embedded ice. the scan chains are controlled by the ice/jtag port. embedded ice mode is selected when jtagsel is low. it is not possible to switch directly between ice and jtag operations. a chip reset must be performed after jtagsel is changed. for further details on the embedded ice, see the arm7tdmi (rev4) technical reference manual (ddi0210b). 13.6.3 debug unit the debug unit provides a two-pin (dxrd and txrd) usart that can be used for several debug and trace purposes and offers an ideal means for in-situ programming solutions and debug monitor communication. moreover, the association with two peripheral data controller channels permits packet handling of these tasks with processor time reduced to a minimum. the debug unit also manages the interrupt handling of the commtx and commrx signals that come from the ice and that trace the activity of the debug communication channel.the debug unit allows blockage of access to the system through the ice interface. the debug unit can be used to upload an applicati on into the internal sram. it is activated by the boot program when no valid application is detected. the protocol used to load the applica- tion is xmodem. a specific register, the debug unit chip id register, gives information about the product ver- sion and its internal configuration. the at91sam7a3 debug unit chip id value is 0x260a0941 on 32-bit width. for further details on the debug unit, see the debug unit section.
45 6042e?atarm?14-dec-06 at91sam7a3 preliminary 13.6.4 ieee 1149.1 jtag boundary scan ieee 1149.1 jtag boundary scan allows pin-level access independent of the device packag- ing technology. ieee 1149.1 jtag boundary scan is enabled when jtagsel is high. the sample, extest and bypass functions are implement ed. in ice debug mode, the arm processor responds with a non-jtag chip id that identifies the processor to the ice system. this is not ieee 1149.1 jtag-compliant. it is not possible to switch directly between jtag and ice operations. a chip reset must be performed after jtagsel is changed. a boundary-scan descriptor language (bsdl) file is provided to set up test. 13.6.4.1 jtag boundary-scan register the boundary-scan register (bsr) contains 186 bi ts that correspond to active pins and asso- ciated control signals. each at91sam7a3 input/output pin corresponds to a 3-bit register in the bsr. the output bit contains data that can be forced on the pa d. the input bit facilitates the observability of data applied to the pad. the control bit selects the direction of the pad. table 13-2. at91sam7a3 jtag bounda ry scan register bit number pin name pin type associated bsr cells 185 pb13 in/out input 184 output 183 control 182 pb12 in/out input 181 output 180 control 179 pb11 in/out input 178 output 177 control 176 pb10 in/out input 175 output 174 control 173 pb9 in/out input 172 output 171 control 170 pb8 in/out input 169 output 168 control
46 6042e?atarm?14-dec-06 at91sam7a3 preliminary 167 pb7 in/out input 166 output 165 control 164 pb6 in/out input 163 output 162 control 161 pb5 in/out input 160 output 159 control 158 pb4 in/out input 157 output 156 control 155 pb3 in/out input 154 output 153 control 152 pb2 in/out input 151 output 150 control 149 pb1 in/out input 148 output 147 control 146 pb0 in/out input 145 output 144 control 143 pa 0 i n / o u t input 142 output 141 control 140 pa 1 i n / o u t input 139 output 138 control 137 pa 2 i n / o u t input 136 output 135 control table 13-2. at91sam7a3 jtag boundary scan register (continued) bit number pin name pin type associated bsr cells
47 6042e?atarm?14-dec-06 at91sam7a3 preliminary 134 pa 3 i n / o u t input 133 output 132 control 131 pa 4 i n / o u t input 130 output 129 control 128 pa 5 i n / o u t input 127 output 126 control 125 pa 6 i n / o u t input 124 output 123 control 122 pa 7 i n / o u t input 121 output 120 control 119 pa 8 i n / o u t input 118 output 117 control 116 pa 9 i n / o u t input 115 output 114 control 113 pa 1 0 i n / o u t input 112 output 111 control 110 pa 1 1 i n / o u t input 109 output 108 control 107 pa 1 2 i n / o u t input 106 output 105 control 104 pa 1 3 i n / o u t input 103 output 102 control table 13-2. at91sam7a3 jtag boundary scan register (continued) bit number pin name pin type associated bsr cells
48 6042e?atarm?14-dec-06 at91sam7a3 preliminary 101 pa 1 4 i n / o u t input 100 output 99 control 98 pa 1 5 i n / o u t input 97 output 96 control 95 pa 1 6 i n / o u t input 94 output 93 control 92 pa 1 7 i n / o u t input 91 output 90 control 89 pa 1 8 i n / o u t input 88 output 87 control 86 pa 1 9 i n / o u t input 85 output 84 control 83 pa 2 0 i n / o u t input 82 output 81 control 80 pa 2 1 i n / o u t input 79 output 78 control 77 pa 2 2 i n / o u t input 76 output 75 control 74 pa 2 3 i n / o u t input 73 output 72 control 71 pa 2 4 i n / o u t input 70 output 69 control table 13-2. at91sam7a3 jtag boundary scan register (continued) bit number pin name pin type associated bsr cells
49 6042e?atarm?14-dec-06 at91sam7a3 preliminary 68 pa 2 5 i n / o u t input 67 output 66 control 65 pa 2 6 i n / o u t input 64 output 63 control 62 pa 2 7 i n / o u t input 61 output 60 control 59 pa 2 8 i n / o u t input 58 output 57 control 56 pa 2 9 i n / o u t input 55 output 54 control 53 pa 3 0 i n / o u t input 52 output 51 control 50 pa 3 1 i n / o u t input 49 output 48 control 47 pb14 in/out input 46 output 45 control 44 pb15 in/out input 43 output 42 control 41 pb16 in/out input 40 output 39 control 38 pb17 in/out input 37 output 36 control table 13-2. at91sam7a3 jtag boundary scan register (continued) bit number pin name pin type associated bsr cells
50 6042e?atarm?14-dec-06 at91sam7a3 preliminary 35 pb18 in/out input 34 output 33 control 32 pb19 in/out input 31 output 30 control 29 pb20 in/out input 28 output 27 control 26 pb21 in/out input 25 output 24 control 23 pb22 in/out input 22 output 21 control 20 pb23 in/out input 19 output 18 control 17 pb24 in/out input 16 output 15 control 14 pb25 in/out input 13 output 12 control 11 pb26 in/out input 10 output 9 control 8 pb27 in/out input 7 output 6 control 5 pb28 in/out input 4 output 3 control table 13-2. at91sam7a3 jtag boundary scan register (continued) bit number pin name pin type associated bsr cells
51 6042e?atarm?14-dec-06 at91sam7a3 preliminary 2 pb29 in/out input 1 output 0 control table 13-2. at91sam7a3 jtag boundary scan register (continued) bit number pin name pin type associated bsr cells
52 6042e?atarm?14-dec-06 at91sam7a3 preliminary 13.6.5 id code register access: read-only version[31:28]: product version number set to 0x1. part number[27:12]: product part number product part number is 0x5b05 manufacturer identity[11:1] set to 0x01f. bit[0] required by ieee std. 1149.1. set to 0x1. jtag id code value is 0x05b0503f 31 30 29 28 27 26 25 24 version part number 23 22 21 20 19 18 17 16 part number 15 14 13 12 11 10 9 8 part number manufacturer identity 76543210 manufacturer identity 1
53 6042e?atarm?14-dec-06 at91sam7a3 preliminary 14. reset controller (rstc) 14.1 overview the reset controller (rstc), based on power-on reset cells, handles all the resets of the sys- tem without any external components. it reports which reset occurred last. the reset controller also drives independently or simultaneously the external reset and the peripheral and processor resets. 14.2 block diagram figure 14-1. reset controller block diagram 14.3 functional description 14.3.1 reset controller overview the reset controller is made up of an nrst manager, a startup counter and a reset state manager. it runs at slow clock and generates the following reset signals: proc_nreset: processor reset line. it also resets the watchdog timer. backup_nreset: affects all the peripherals powered by vddbu. periph_nreset: affects the whole set of embedded peripherals. nrst_out: drives the nrst pin. these reset signals are asserted by the reset controller, either on external events or on soft- ware action. the reset state manager controls th e generation of reset signals and provides a signal to the nrst manager when an assertion of the nrst pin is required. the nrst manager sha pes the nrst assertion during a pr ogrammable time, thus controlling external device resets. nrst startup counter proc_nreset wd_fault periph_nreset backup_neset slck reset state manager reset controller rstc_irq nrst manager exter_nreset nrst_out main supply por wdrproc user_reset backup supply por
54 6042e?atarm?14-dec-06 at91sam7a3 preliminary the startup counte r waits for the complete crystal oscillato r startup. the wait delay is given by the crystal oscillator startup time maximum value that can be found in the section crystal oscillator characteristics in the electrical characteristics section of the product documentation. the reset controller mode register (rstc_mr), allowing the configuration of the reset con- troller, is powered with vddbu, so that its configuration is saved as long as vddbu is on. 14.3.2 nrst manager the nrst manager samples the nrst input pin and drives this pin low when required by the reset state manager. figure 14-2 shows the block diagram of the nrst manager. figure 14-2. nrst manager 14.3.2.1 nrst signal or interrupt the nrst manager samples the nrst pin at slow clock speed. when the line is detected low, a user reset is reported to the reset state manager. however, the nrst manager can be programmed to not trigger a reset when an assertion of nrst occurs. writing the bit ursten at 0 in rstc_mr disables the user reset trigger. the level of the pin nrst can be read at any time in the bit nrstl (nrst level) in rstc_sr. as soon as the pin nrst is asserted, the bit ursts in rstc_sr is set. this bit clears only when rstc_sr is read. the reset controller can also be programmed to generate an interrupt instead of generating a reset. to do so, the bit urstien in rstc_mr must be written at 1. 14.3.2.2 nrst external reset control the reset state manager asserts the signal ext_nreset to assert the nrst pin. when this occurs, the ?nrst_out? signal is driven low by the nrst manager for a time programmed by the field erstl in rstc_mr. this assertio n duration, named external_reset_length, lasts 2 (erstl+1) slow clock cycles. this gives the approximate duration of an assertion between 60 s and 2 seconds. note that erstl at 0 defines a two-cycle duration for the nrst pulse. external reset timer ursts ursten erstl exter_nreset urstien rstc_mr rstc_mr rstc_mr rstc_sr nrstl nrst_out nrst rstc_irq other interrupt sources user_reset
55 6042e?atarm?14-dec-06 at91sam7a3 preliminary this feature allows the reset controller to shape the nrst pin level, and thus to guarantee that the nrst line is driven low for a time co mpliant with potential external devices connected on the system reset. as the field is within rstc_mr, which is bac ked-up, this field can be used to shape the sys- tem power-up reset for devices r equiring a longer star tup time than the sl ow clock oscillator. 14.3.3 reset states the reset state manager handles the different reset sources and generates the internal reset signals. it reports the reset status in the field rsttyp of the status register (rstc_sr). the update of the field rsttyp is performed when the processor reset is released. 14.3.3.1 general reset a general reset occurs when vd dbu is powered on. the backup supply por cell output rises and is filtered with a startup counter, which o perates at slow clock. the purpose of this counter is to make sure the slow clock oscillator is stable before starting up the device. the length of startup time is hardcoded to comply with the slow clock oscillator startup time. after this time, the processor clock is released at slow clock and all the other signals remains valid for 3 cycles for proper processor and logic reset. then, all the reset signals are released and the field rsttyp in rstc_sr reports a general reset. as the rstc_mr is reset, the nrst line rises 2 cycles after the backup_nreset, as erstl defaults at value 0x0. when vddbu is detected low by the backup supp ly por cell, all resets signals are immedi- ately asserted, even if the main supply por cell does not report a main supply shut down. figure 14-3 shows how the general reset affects the reset signals. figure 14-3. general reset state slck periph_nreset proc_nreset backup supply por output nrst (nrst_out) external reset length = 2 cycles startup time mck processor startup = 3 cycles backup_nreset any freq. rsttyp xxx 0x0 = general reset xxx
56 6042e?atarm?14-dec-06 at91sam7a3 preliminary 14.3.3.2 wake-up reset the wake-up reset occurs when the main supply is down. when the main supply por out- put is active, all the reset signals are assert ed except backup_nreset. when the main supply powers up, the por output is resynchronized on slow clock. the processor clock is then re- enabled during 3 slow clock cycles, dependi ng on the requirements of the arm processor. at the end of this delay, the processor and other reset signals rise. the field rsttyp in rstc_sr is updated to report a wake-up reset. the ?nrst_out? remains asserted for exter nal_reset_length cycles. as rstc_mr is backed-up, the programmed number of cycles is applicable. when the main supply is detected falling, the reset signals are immediately asserted. this transition is synchronous with the output of the main supply por. figure 14-4. wake-up state 14.3.3.3 user reset the user reset is entered when a low level is detected on the nrst pin and the bit ursten in rstc_mr is at 1. the nrst input signal is resynchronized with slck to insure proper behavior of the system. the user reset is entered as soon as a low le vel is detected on nrst. the processor reset and the peripheral reset are asserted. the user reset is left when nrst rises, afte r a two-cycle resynchroniz ation time and a three- cycle processor startup. the processor clock is re-enabled as soon as nrst is confirmed high. when the processor reset signal is released, the rsttyp field of the status register (rstc_sr) is loaded with the value 0x4, indicating a user reset. slck periph_nreset proc_nreset main supply por output nrst (nrst_out) external reset length = 4 cycles (erstl = 1) mck processor startup = 3 cycles backup_nreset any freq. resynch. 2 cycles rsttyp xxx 0x1 = wakeup reset xxx
57 6042e?atarm?14-dec-06 at91sam7a3 preliminary the nrst manager guarantees that the nrst line is asserted for external_reset_length slow clock cycles, as programmed in the field erstl. how- ever, if nrst does not rise after extern al_reset_length because it is driven low externally, the internal reset lines rema in asserted until nrs t actually rises. figure 14-5. user reset state 14.3.3.4 software reset the reset controller offers several commands used to assert the different reset signals. these commands are performed by writing the control register (rst c_cr) with the following bits at 1: procrst: writing procrst at 1 resets the processor and the watchdog timer. perrst: writing perrst at 1 resets all the embedded peripherals, including the memory system, and, in particular, the remap command. the peripheral reset is generally used for debug purposes. extrst: writing extrst at 1 asserts low the nrst pin during a time defined by the field erstl in the mode register (rstc_mr). the software reset is entered if at least one of these bits is set by the software. all these com- mands can be performed independently or simultaneously. the software reset lasts 3 slow clock cycles. the internal reset signals are asserted as soon as the register write is performed. this is detected on the master clock (mck). they are re leased when the software reset is left, i.e.; synchronously to slck. if extrst is set, the nrst_out signal is asserted depending on the programming of the field erstl. however, the result ing falling edge on nrst does not lead to a user reset. slck periph_nreset proc_nreset nrst nrst (nrst_out) >= external reset length mck processor startup = 3 cycles any freq. resynch. 2 cycles rsttyp any xxx resynch. 2 cycles 0x4 = user reset
58 6042e?atarm?14-dec-06 at91sam7a3 preliminary if and only if the procrst bit is set, the reset controller reports the software status in the field rsttyp of the status register (rstc_sr). other software resets are not reported in rsttyp. as soon as a software operation is detected, the bit srcmp (software reset command in progress) is set in the status register (rstc_sr). it is cleared as soon as the software reset is left. no other software reset can be performed while the srcmp bit is set, and writing any value in rstc_cr has no effect. figure 14-6. software reset 14.3.3.5 watchdog reset the watchdog reset is entered when a watchdog fault occurs. this state lasts 3 slow clock cycles. when in watchdog reset, assertion of the reset signals depends on the wdrproc bit in wdt_mr: if wdrproc is 0, the processor reset and the peripheral reset are asserted. the nrst line is also asserted, depending on the programming of the field erstl. however, the resulting low level on nrst does not result in a user reset state. if wdrproc = 1, only the processor reset is asserted. the watchdog timer is reset by the proc_nrese t signal. as the watchdog fault always causes a processor reset if wdrsten is set, the watchdog timer is always reset after a watchdog reset, and the watchdog is enabled by default and with a period set to a maximum. when the wdrsten in wdt_mr bit is reset, t he watchdog fault has no impact on the reset controller. slck periph_nreset if perrst=1 proc_nreset if procrst=1 write rstc_cr nrst (nrst_out) if extrst=1 external reset length 8 cycles (erstl=2) mck processor startup = 3 cycles any freq. rsttyp any xxx 0x3 = software reset resynch. 1 cycle srcmp in rstc_sr
59 6042e?atarm?14-dec-06 at91sam7a3 preliminary figure 14-7. watchdog reset 14.3.4 reset state priorities the reset state manager manages the following priorities between the different reset sources, given in descending order: backup reset wake-up reset watchdog reset software reset user reset particular cases are listed below: when in user reset: ? a watchdog event is impossible because the watchdog timer is being reset by the proc_nreset signal. ? a software reset is impossible, since the processor reset is being activated. when in software reset: ? a watchdog event has priority over the current state. ? the nrst has no effect. when in watchdog reset: ? the processor reset is active and so a software reset cannot be programmed. ? a user reset cannot be entered. only if wdrproc = 0 slck periph_nreset proc_nreset wd_fault nrst (nrst_out) external reset length 8 cycles (erstl=2) mck processor startup = 3 cycles any freq. rsttyp any xxx 0x2 = watchdog reset
60 6042e?atarm?14-dec-06 at91sam7a3 preliminary 14.3.5 reset controller status register the reset controller status register (rstc_sr) provides several status fields: rsttyp field: this field gives the type of the last reset, as explained in previous sections. srcmp bit: this field indicates that a software reset command is in progress and that no further software reset should be performed until the end of the current one. this bit is automatically cleared at the end of the current software reset. nrstl bit: the nrstl bit of the status register gives the level of the nrst pin sampled on each mck rising edge. ursts bit: a high-to-low transition of the nrst pin sets the ursts bit of the rstc_sr register. this transition is also detected on the master clock (mck) rising edge (see figure 14-8 ). if the user reset is disabled (ursten = 0) and if the interruption is enabled by the urstien bit in the rstc_mr register, the ursts bit triggers an interrupt. reading the rstc_sr status register resets the ursts bit and clears the interrupt. figure 14-8. reset controller status and interrupt mck nrst nrstl 2 cycle resynchronization 2 cycle resynchronization ursts read rstc_sr peripheral access rstc_irq if (ursten = 0) and (urstien = 1)
61 6042e?atarm?14-dec-06 at91sam7a3 preliminary 14.4 reset controller (rstc) user interface note: 1. the reset value of rstc_sr either reports a general reset or a wake-up reset depending on last rising power supply. table 14-1. reset controller (rstc) register mapping offset register name access reset value back-up reset value 0x00 control register rstc_cr write-only - 0x04 status register rstc_sr read-only 0x0000_0001 0x0000_0000 0x08 mode register rstc_mr read/write - 0x0000_0000
62 6042e?atarm?14-dec-06 at91sam7a3 preliminary 14.4.1 reset controller control register register name: rstc_cr access type: write-only procrst: processor reset 0 = no effect. 1 = if key is correct, resets the processor. perrst: peripheral reset 0 = no effect. 1 = if key is correct, resets the peripherals. extrst: external reset 0 = no effect. 1 = if key is correct, asserts the nrst pin. key: password should be written at value 0xa5. writing any other value in this field aborts the write operation. 31 30 29 28 27 26 25 24 key 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ?????? ? 76543210 ????extrstperrst?procrst
63 6042e?atarm?14-dec-06 at91sam7a3 preliminary 14.4.2 reset controller status register register name: rstc_sr access type: read-only ursts: user reset status 0 = no high-to-low edge on nrst happened since the last read of rstc_sr. 1 = at least one high-to-low transition of nrst has been detected since the last read of rstc_sr. rsttyp: reset type reports the cause of the last processor reset. r eading this rstc_sr does not reset this field. nrstl: nrst pin level registers the nrst pin level at master clock (mck). srcmp: software reset command in progress 0 = no software command is being performed by the reset controller. the reset controller is ready for a software command. 1 = a software reset command is being performed by the reset controller. the reset controller is busy. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ??????srcmpnrstl 15 14 13 12 11 10 9 8 ????? rsttyp 76543210 ?????? ursts rsttyp reset type comments 0 0 0 general reset both vdd1v8 and vddbu rising 0 0 1 wake up reset vdd1v8 rising 0 1 0 watchdog reset watchdog fault occurred 0 1 1 software reset processor re set required by the software 1 0 0 user reset nrst pin detected low
64 6042e?atarm?14-dec-06 at91sam7a3 preliminary 14.4.3 reset controller mode register register name: rstc_mr access type: read/write ursten: user reset enable 0 = the detection of a low level on the pin nrst does not generate a user reset. 1 = the detection of a low level on the pin nrst triggers a user reset. urstien: user reset interrupt enable 0 = usrts bit in rstc_sr at 1 has no effect on rstc_irq. 1 = usrts bit in rstc_sr at 1 asserts rstc_irq if ursten = 0. erstl: external reset length this field defines the external reset length. the external reset is asserted during a time of 2 (erstl+1) slow clock cycles. this allows assertion duration to be programmed between 60 s and 2 seconds. key: password should be written at value 0xa5. writing any other value in this field aborts the write operation. 31 30 29 28 27 26 25 24 key 23 22 21 20 19 18 17 16 ??????? 15 14 13 12 11 10 9 8 ???? erstl 76543210 ? ? urstien ? ? ? ursten
65 6042e?atarm?14-dec-06 at91sam7a3 preliminary 15. real-time timer (rtt) 15.1 overview the real-time timer is built around a 32-bit coun ter and used to count elapsed seconds. it gen- erates a periodic interrupt or/and triggers an alarm on a programmed value. 15.2 block diagram figure 15-1. real-time timer 15.3 functional description the real-time timer is used to count elapsed seconds. it is built around a 32-bit counter fed by slow clock divided by a programmable 16-bit va lue. the value can be programmed in the field rtpres of the real-time mode register (rtt_mr). programming rtpres at 0x00008000 corresponds to feeding the real-time counter with a 1 hz signal (if the slow clock is 32.768 hz). the 32-bit counter can count up to 2 32 seconds, corre- sponding to more than 136 years, then roll over to 0. the real-time timer can also be used as a free -running timer with a lower time-base. the best accuracy is achieved by writing rtpres to 3. programming rtpres to 1 or 2 is possible, but may result in losing status events because the stat us register is cleared two slow clock cycles after read. thus if the rtt is configured to trigger an interrupt, the interrupt occurs during 2 slow clock cycles after reading rtt_sr. to prevent se veral executions of the interrupt handler, the interrupt must be disabled in the interrupt handl er and re-enabled when the status register is clear. slck rtpres rttinc alms 16-bit divider 32-bit counter almv = crtv rtt_mr rtt_vr rtt_ar rtt_sr rttincien rtt_mr 0 10 almien rtt_int rtt_mr set set rtt_sr read rtt_sr reset reset rtt_mr reload rtt_alarm rttrst rtt_mr rttrst
66 6042e?atarm?14-dec-06 at91sam7a3 preliminary the real-time timer value (crtv) can be read at any time in the register rtt_vr (real-time value register). as this value can be updated asynchronously from the master clock, it is advis- able to read this register twice at the same value to improve accuracy of the returned value. the current value of the counter is compared with the value written in the alarm register rtt_ar (real-time alarm register). if the counter value matches the alarm, the bit alms in rtt_sr is set. the alarm register is set to its maximum value, corresponding to 0xffff_ffff, after a reset. the bit rttinc in rtt_sr is set each time the real-time timer counter is incremented. this bit can be used to start a periodic interrupt, the period being one second when the rtpres is pro- grammed with 0x8000 and slow clock equal to 32.768 hz. reading the rtt_sr status register resets the rttinc and alms fields. writing the bit rttrst in rtt_mr immediately re loads and restarts the clock divider with the new programmed value. this also resets the 32-bit counter. note: because of the asynchronism between the slow clock (sclk) and the system clock (mck): 1) the restart of the counter and the reset of the rtt_vr current value register is effective only 2 slow clock cycles after the write of th e rttrst bit in the rtt_mr register. 2) the status register fl ags reset is taken into account only 2 sl ow clock cycles after the read of the rtt_sr (status register). figure 15-2. rtt counting prescaler almv almv-1 0 almv+1 0 rtpres - 1 rtt apb cycle read rtt_sr alms (rtt_sr) apb interface mck rttinc (rtt_sr) almv+2 almv+3 ... apb cycle
67 6042e?atarm?14-dec-06 at91sam7a3 preliminary 15.4 real-time timer (rtt) user interface table 15-1. real-time timer (rtt) register mapping offset register name access reset value 0x00 mode register rtt_mr read/write 0x0000_8000 0x04 alarm register rtt_ar read/write 0xffff_ffff 0x08 value register rtt_vr read-only 0x0000_0000 0x0c status register rtt_sr read-only 0x0000_0000
68 6042e?atarm?14-dec-06 at91sam7a3 preliminary 15.4.1 real-time timer mode register register name: rtt_mr access type: read/write rtpres: real-time timer prescaler value defines the number of slck periods required to increment the real-time timer. rtpres is defined as follows: rtpres = 0: the prescaler period is equal to 2 16 rtpres 0: the prescaler period is equal to rtpres. almien: alarm interrupt enable 0 = the bit alms in rtt_sr has no effect on interrupt. 1 = the bit alms in rtt_sr asserts interrupt. rttincien: real-time timer increment interrupt enable 0 = the bit rttinc in rtt_sr has no effect on interrupt. 1 = the bit rttinc in r tt_sr asserts interrupt. rttrst: real-time timer restart 1 = reloads and restarts the clock divider with the new programmed value. this also resets the 32-bit counter. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ?????rttrstrttincienalmien 15 14 13 12 11 10 9 8 rtpres 76543210 rtpres
69 6042e?atarm?14-dec-06 at91sam7a3 preliminary 15.4.2 real-time timer alarm register register name: rtt_ar access type: read/write almv: alarm value defines the alarm value (almv+1) compared with the real-time timer. 15.4.3 real-time timer value register register name: rtt_vr access type: read-only crtv: current real-time value returns the current value of the real-time timer. 31 30 29 28 27 26 25 24 almv 23 22 21 20 19 18 17 16 almv 15 14 13 12 11 10 9 8 almv 76543210 almv 31 30 29 28 27 26 25 24 crtv 23 22 21 20 19 18 17 16 crtv 15 14 13 12 11 10 9 8 crtv 76543210 crtv
70 6042e?atarm?14-dec-06 at91sam7a3 preliminary 15.4.4 real-time timer status register register name: rtt_sr access type: read-only alms: real-time alarm status 0 = the real-time alarm has not occurred since the last read of rtt_sr. 1 = the real-time alarm occurred since the last read of rtt_sr. rttinc: real-time timer increment 0 = the real-time timer has not been incremented since the last read of the rtt_sr. 1 = the real-time timer has been incremented since the last read of the rtt_sr. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ???????? 76543210 ??????rttincalms
71 6042e?atarm?14-dec-06 at91sam7a3 preliminary 16. periodic interval timer (pit) 16.1 overview the periodic interval timer (pit) provides the operating system?s scheduler interrupt. it is designed to offer maximum accuracy and efficient management, even for systems with long response time. 16.2 block diagram figure 16-1. periodic interval timer 16.3 functional description the periodic interval timer aims at providing periodic interrupts for use by operating systems. the pit provides a programmable overflow counter and a reset-on-read feature. it is built around two counters: a 20-bit cpiv counter and a 12-bit picnt counter. both counters work at master clock /16. the first 20-bit cpiv counter increments from 0 up to a programmable overflow value set in the field piv of the mode register (pit_mr). when the counter cpiv reaches this value, it resets to 0 and increments the periodic interval counter, picnt. the status bit pits in the status register (pit_sr) rises and triggers an interrupt, provided the interrupt is enabled (pitien in pit_mr). writing a new piv value in pit_mr does not reset/restart the counters. 20-bit counter mck/16 piv pit_mr cpiv pit_pivr picnt 12-bit adder 0 0 read pit_pivr cpiv picnt pit_piir pits pit_sr set reset pitien pit_mr pit_irq 1 0 1 0 mck prescaler = ?
72 6042e?atarm?14-dec-06 at91sam7a3 preliminary when cpiv and picnt values are obtained by r eading the periodic interval value register (pit_pivr), the overflow counter (picnt) is reset and the pits is cleared, thus acknowledg- ing the interrupt. the value of picnt gives the number of periodic intervals elapsed since the last read of pit_pivr. when cpiv and picnt values are obtained by reading the periodic interval image register (pit_piir), there is no effect on the counters cpiv and picnt, nor on the bit pits. for exam- ple, a profiler can read pit_piir without clearing any pending interrupt, whereas a timer interrupt clears the interrupt by reading pit_pivr. the pit may be enabled/disabled using the piten bit in the pit_mr register (disabled on reset). the piten bit only becomes effective when the cpiv value is 0. figure 16-2 illustrates the pit counting. after the pit enable bit is reset (piten= 0), the cpiv goes on counting until the piv value is reached, and is then reset. pit restarts counting, only if the piten is set again. the pit is stopped when the core enters debug state. figure 16-2. enabling/disabling pit with piten mck prescaler piv piv - 1 0 piten 10 0 15 cpiv 1 restarts mck prescaler 0 1 apb cycle read pit_pivr 0 picnt pits (pit_sr) mck apb interface apb cycle
73 6042e?atarm?14-dec-06 at91sam7a3 preliminary 16.4 periodic interval time r (pit) user interface 16.4.1 periodic interval timer mode register register name: pit_mr access type: read/write piv: periodic interval value defines the value compared with the primary 20-bit counter of the periodic interval timer (cpiv). the period is equal to (piv + 1). piten: period interval timer enabled 0 = the periodic interval timer is disabled when the piv value is reached. 1 = the periodic interval timer is enabled. pitien: periodic interval timer interrupt enable 0 = the bit pits in pit_sr has no effect on interrupt. 1 = the bit pits in pit_sr asserts interrupt. table 16-1. periodic interval timer (pit) register mapping offset register name access reset value 0x00 mode register pit_mr read/write 0x000f_ffff 0x04 status register pit_sr read-only 0x0000_0000 0x08 periodic interval value register pit_pivr read-only 0x0000_0000 0x0c periodic interval image register pit_piir read-only 0x0000_0000 31 30 29 28 27 26 25 24 ??????pitienpiten 23 22 21 20 19 18 17 16 ???? piv 15 14 13 12 11 10 9 8 piv 76543210 piv
74 6042e?atarm?14-dec-06 at91sam7a3 preliminary 16.4.2 periodic interval timer status register register name: pit_sr access type: read-only pits: periodic interval timer status 0 = the periodic interval timer has not reached piv since the last read of pit_pivr. 1 = the periodic interval timer has reached piv since the last read of pit_pivr. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ???????? 76543210 ???????pits
75 6042e?atarm?14-dec-06 at91sam7a3 preliminary 16.4.3 periodic interval timer value register register name: pit_pivr access type: read-only reading this register clears pits in pit_sr. cpiv: current periodic interval value returns the current value of the periodic interval timer. picnt: periodic interval counter returns the number of occurrences of periodic intervals since the last read of pit_pivr. 31 30 29 28 27 26 25 24 picnt 23 22 21 20 19 18 17 16 picnt cpiv 15 14 13 12 11 10 9 8 cpiv 76543210 cpiv
76 6042e?atarm?14-dec-06 at91sam7a3 preliminary 16.4.4 periodic interval timer image register register name: pit_piir access type: read-only cpiv: current periodic interval value returns the current value of the periodic interval timer. picnt: periodic interval counter returns the number of occurrences of periodic intervals since the last read of pit_pivr. 31 30 29 28 27 26 25 24 picnt 23 22 21 20 19 18 17 16 picnt cpiv 15 14 13 12 11 10 9 8 cpiv 76543210 cpiv
77 6042e?atarm?14-dec-06 at91sam7a3 preliminary 17. watchdog timer (wdt) 17.1 overview the watchdog timer can be used to prevent system lock-up if the software becomes trapped in a deadlock. it features a 12-bit down counter that allows a watchdog period of up to 16 seconds (slow clock at 32.768 khz). it can generate a general reset or a processor reset only. in addition, it can be stopped while the processor is in debug mode or idle mode. 17.2 block diagram figure 17-1. watchdog timer block diagram = 0 10 set reset read wdt_sr or reset wdt_fault (to reset controller) set reset wdfien wdt_int wdt_mr slck 1/128 12-bit down counter current value wdd wdt_mr <= wdd wdv wdrstt wdt_mr wdt_cr reload wdunf wderr reload write wdt_mr wdt_mr wdrsten
78 6042e?atarm?14-dec-06 at91sam7a3 preliminary 17.3 functional description the watchdog timer can be used to prevent system lock-up if the software becomes trapped in a deadlock. it is supplied with vddcore. it re starts with initial values on processor reset. the watchdog is built around a 12-bit down counter, which is loaded with the value defined in the field wdv of the mode register (wdt_mr). the watchdog timer uses the slow clock divided by 128 to establish the maximum watchdog period to be 16 seconds (with a typical slow clock of 32.768 khz). after a processor reset, the value of wdv is 0xfff, corresponding to the maximum value of the counter with the external reset generation enabled (field wdrsten at 1 after a backup reset). this means that a default watchdog is running at reset, i.e., at power-up. the user must either disable it (by setting the wddis bit in wd t_mr) if he does not expect to use it or must reprogram it to meet the maximum watchdog period the application requires. the watchdog mode register (wdt_mr) can be written only once. only a processor reset resets it. writing the wdt_mr register reloads the timer with the newly programmed mode parameters. in normal operation, the user reloads the watchdog at regular intervals before the timer under- flow occurs, by writing the control register (wdt_cr) with the bit wdrstt to 1. the watchdog counter is then immediately reloaded from wdt_mr and restarted, and the slow clock 128 divider is reset and restarted. the wdt_cr register is write-protected. as a result, writing wdt_cr without the correct hard-coded key has no effect. if an underflow does occur, the ?wdt_fault? signal to the reset controller is asserted if the bit wdrsten is set in the mode register (wdt_mr). moreover, the bit wdunf is set in the watchdog status register (wdt_sr). to prevent a software deadlock that continuously triggers the watchdog, the reload of the watchdog must occur while the watchdog count er is within a window between 0 and wdd, wdd is defined in the watchdog mode register wdt_mr. any attempt to restart the watchdog while the watchdog counter is between wdv and wdd results in a watchdog error, even if the watchdog is disabled. the bit wderr is updated in the wdt_sr and the ?wdt_fault? signal to the reset controller is asserted. note that this feature can be disabled by programming a wdd value greater than or equal to the wdv value. in such a configuration, restarti ng the watchdog timer is permitted in the whole range [0; wdv] and does not generate an error. this is the default configuration on reset (the wdd and wdv values are equal). the status bits wdunf (watchdog underflow ) and wderr (watchdog error) trigger an inter- rupt, provided the bit wdfien is set in the mode register. the signal ?wdt_fault? to the reset controller causes a watchdog reset if the wdrsten bit is set as already explained in the reset controller programmer datasheet. in that case, the processor and the watchdog timer are reset, and the wderr and wdunf flags are reset. if a reset is generated or if wdt_sr is read, the status bits are reset, the interrupt is cleared, and the ?wdt_fault? signal to the reset controller is deasserted. writing the wdt_mr reloads and restarts the down counter. while the processor is in debug state or in idle mode, the counter may be stopped depending on the value programmed for the bits wdidlehlt and wddbghlt in the wdt_mr.
79 6042e?atarm?14-dec-06 at91sam7a3 preliminary figure 17-2. watchdog behavior 0 wdv wdd wdt_cr = wdrstt watchdog fault normal behavior watchdog error watchdog underflow fff if wdrsten is 1 if wdrsten is 0 forbidden window permitted window
80 6042e?atarm?14-dec-06 at91sam7a3 preliminary 17.4 watchdog timer (wdt) user interface 17.4.1 watchdog timer control register register name: wdt_cr access type: write-only wdrstt: watchdog restart 0: no effect. 1: restarts the watchdog. key: password should be written at value 0xa5. writing any other value in this field aborts the write operation. table 17-1. watchdog timer (wdt) register mapping offset register name access reset value 0x00 control register wdt_cr write-only - 0x04 mode register wdt_mr read/write once 0x3fff_2fff 0x08 status register wdt_sr read-only 0x0000_0000 31 30 29 28 27 26 25 24 key 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ???????? 76543210 ???????wdrstt
81 6042e?atarm?14-dec-06 at91sam7a3 preliminary 17.4.2 watchdog timer mode register register name: wdt_mr access type: read/write once wdv: watchdog counter value defines the value loaded in the 12-bit watchdog counter. wdfien: watchdog fault interrupt enable 0: a watchdog fault (underflow or error) has no effect on interrupt. 1: a watchdog fault (underflow or error) asserts interrupt. wdrsten: watchdog reset enable 0: a watchdog fault (underflow or error) has no effect on the resets. 1: a watchdog fault (underflow or error) triggers a watchdog reset. wdrproc: watchdog reset processor 0: if wdrsten is 1, a watchdog fault (underflow or error) activates all resets. 1: if wdrsten is 1, a watchdog fault (underflow or error) activates the processor reset. wdd: watchdog delta value defines the permitted range for reloading the watchdog timer. if the watchdog timer value is less than or equal to w dd, writing wdt_cr with wdrs tt = 1 restarts the timer. if the watchdog timer value is greater than wdd, writing wdt_cr with wdrstt = 1 causes a watchdog error. wddbghlt: watchdog debug halt 0: the watchdog runs when the processor is in debug state. 1: the watchdog stops when the processor is in debug state. wdidlehlt: watchdog idle halt 0: the watchdog runs when the system is in idle mode. 1: the watchdog stops when the system is in idle state. wddis: watchdog disable 0: enables the watchdog timer. 1: disables the watchdog timer. 31 30 29 28 27 26 25 24 ? ? wdidlehlt wddbghlt wdd 23 22 21 20 19 18 17 16 wdd 15 14 13 12 11 10 9 8 wddis wdrproc wdrsten wdfien wdv 76543210 wdv
82 6042e?atarm?14-dec-06 at91sam7a3 preliminary 17.4.3 watchdog timer status register register name: wdt_sr access type: read-only wdunf: watchdog underflow 0: no watchdog underflow occurred since the last read of wdt_sr. 1: at least one watchdog underflow occurred since the last read of wdt_sr. wderr: watchdog error 0: no watchdog error occurred since the last read of wdt_sr. 1: at least one watchdog error occurred since the last read of wdt_sr. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ???????? 76543210 ??????wderrwdunf
83 6042e?atarm?14-dec-06 at91sam7a3 preliminary 18. shutdown controller (shdwc) 18.1 overview the shutdown controller contro ls the power supplies vdd3v3 and vdd1v8 and the wake-up detection on debounced input lines. a dedicated input, force wake up, is also available. 18.2 block diagram figure 18-1. shutdown contro ller block diagram shutdown wake-up shutdown output controller shdw wkup0 event detector shdw wkup1 wkmode1 wkmode0 fwkup shutdown controller rtt alarm rttwken sysc_shmr sysc_shmr sysc_shcr cptwk0 cptwk1 event0 event1 wakeup0 wakeup1 rttwk sysc_shsr sysc_shsr sysc_shsr set set set reset reset reset read sysc_shsr read sysc_shsr read sysc_shsr slck fwkup sysc_shsr set read sysc_shsr reset
84 6042e?atarm?14-dec-06 at91sam7a3 preliminary 18.3 i/o lines description 18.4 product dependencies 18.4.1 power management the shutdown controller is continuously clocked by slow clock. the power management controller has no effect on the behavior of the shutdown controller. 18.5 functional description the shutdown controller manages the main power supply. to do so, it is supplied with vddbu and manages wake-up input pins and one output pin, shdw. a typical application connects th e pin shdw to the shutdown input of the dc/dc converter providing the main power supplies of the system, and especially vdd1v8 and/or vdd3v3. the wake-up inputs (wkup0, wkup1, fwkup) connect to any push-buttons or signal that wake up the system. the software is able to control the pin shdw by writing the shutdown control register (shdw_cr) with the bit shdw at 1. this regi ster is password-protected and so the value written should contain the correct key for the command to be taken into account. as a result, the system should be powered down. a level change on wkup0 or wkup1 is used as wake-up. wake-up is configured in the shut- down mode register (shdw_mr). the transition detector can be programmed to detect either a positive or negative transition or any level change on wkup0 and wkup1. the detection can also be disabled. programming is performed by defining wkmode0 and wkmode1. moreover, a debouncing circuit can be program med for wkup0 or wkup1. the debouncing circuit filters pulses on wkup0 or wkup1 shorter than the programmed number of 16 slck cycles in cptwk0 or cptwk1 of the shdw_mr register. if the programmed level change is detected on a pin, a counter starts. when the counter reaches the value programmed in the corresponding field, cptwk0 or cptwk1, the sh dw pin is released. if a new input change is detected before the counter reaches the corresponding value, the counter is stopped and cleared. wakeup0 and/or wakeup1 of the stat us register (shdw_sr) reports the detec- tion of the programmed events on wkup0 or wkup1, with a reset after the read of shdw_sr. the shutdown controller can be programmed so as to activate the wake-up using the rtt alarm (the detection of the rising edge of the rtt alarm is synchronized with slck). this is done by writing the shdw_mr register usin g the rttwken fields. when enabled, the detec- tion of the rtt alarm is reported in the rttwk bit of the shdw_sr status register. it is reset table 18-1. i/o lines description name description type fwkup force wake up input for the shutdown controller input wkup0 wake-up 0 input input wkup1 wake-up 1input input shdw shutdown output output
85 6042e?atarm?14-dec-06 at91sam7a3 preliminary after the read of shdw_sr. when using the r tt alarm to wake up the system, the user must ensure that the rtt alarm status flag is cleared before shutting down the system. otherwise, no rising edge of the status flag may be detected and the wake-up fails. the pin fwkup is treated differently and a low le vel on this pin forces a de-assertion of the shdw pin, regardless of the presence of the sl ow clock. the bit fwkup in the status register reports a forced wakeup event after internal resynchronization of the event with the slow clock.
86 6042e?atarm?14-dec-06 at91sam7a3 preliminary 18.6 shutdown controller (shdwc) user interface 18.6.1 register mapping 18.6.2 shutdown control register register name: shdw_cr access type: write-only shdw: shut down command 0 = no effect. 1 = if key is correct, asserts the shdw pin. key: password should be written at value 0xa5. writing any other value in this field aborts the write operation. table 18-2. shutdown controller (shdwc) registers offset register name access reset value 0x00 shutdown control register shdw_cr write-only - 0x04 shutdown mode register shdw_mr read-write 0x0000_0303 0x18 shutdown status register shdw_sr read-only 0x0000_0000 31 30 29 28 27 26 25 24 key 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ???????? 76543210 ???????shdw
87 6042e?atarm?14-dec-06 at91sam7a3 preliminary 18.6.3 shutdown mode register register name: shdw_mr access type: read/write wkmode0: wake-up mode 0 wkmode1: wake-up mode 1 cptwk0: counter on wake-up 0 cptwk1: counter on wake-up 1 defines the number of 16 slow clock cycles, the level detection on the corresponding input pin shall last before the wake- up event occurs. because of the internal synchronizati on of wkup0 and wkup1, t he shdw pin is released (cptwk x 16 + 1) slow clock cycles after the event on wkup. rttwken: real-time timer wake-up enable 0 = the rtt alarm signal has no effect on the shutdown controller. 1 = the rtt alarm signal forces the de-assertion of the shdw pin. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????rttwken 15 14 13 12 11 10 9 8 cptwk1 ? ? wkmode1 76543210 cptwk0 ? ? wkmode0 wkmode[1:0] wake-up inpu t transition selection 0 0 none. no detection is performed on the wake-up input 0 1 low to high level 1 0 high to low level 1 1 both levels change
88 6042e?atarm?14-dec-06 at91sam7a3 preliminary 18.6.4 shutdown status register register name: shdw_sr access type: read-only wakeup0: wake-up 0 status wakeup1: wake-up 1 status 0 = no wake-up event occurred on the corresponding wake-up input since the last read of shdw_sr. 1 = at least one wake-up event occurred on the corresponding wake-up input since the last read of shdw_sr. fwkup: force wake up status 0 = no wake-up event occurred on the force wake up input since the last read of shdw_sr. 1 = at least one wake-up event occurred on the force wake up input since the last read of shdw_sr. rttwk: real-time timer wake-up 0 = no wake-up alarm from the rtt occurred since the last read of shdw_sr. 1 = at least one wake-up alarm from the rtt occurred since the last read of shdw_sr. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????rttwk 15 14 13 12 11 10 9 8 ???????? 76543210 ?????fwkupw akeup1 wakeup0
89 6042e?atarm?14-dec-06 at91sam7a3 preliminary 19. memory controller (mc) 19.1 overview the memory controller (mc) manages the asb bus and controls accesses requested by the masters, typically the arm7tdmi processor and the peripheral data controller. it features a simple bus arbiter, an address decoder, an abort status, a misalignment detector and an embedded flash controller. in addition, the mc contains a memory protection unit (mpu) consisting of 16 areas that can be protected ag ainst write and/or user accesses. access to peripherals can be protected in the same way. 19.2 block diagram figure 19-1. memory controller block diagram arm7tdmi processor bus arbiter peripheral data controller memory controller abort asb abort status address decoder user interface peripheral 0 peripheral 1 internal ram apb apb bridge misalignment detector from master to slave peripheral n embedded flash controller internal flash memory protection unit
90 6042e?atarm?14-dec-06 at91sam7a3 preliminary 19.3 functional description the memory controller handles the internal asb bus and arbitrates the accesses of both masters. it is made up of: a bus arbiter an address decoder an abort status a misalignment detector a memory protection unit an embedded flash controller the mc handles only little-endian mode accesses . the masters work in little-endian mode only. 19.3.1 bus arbiter the memory controller has a simple, hard-wired pr iority bus arbiter that gives the control of the bus to one of the two masters. the peripheral data controller has the highest priority; the arm processor has the lowest one. 19.3.2 address decoder the memory controller features an address decoder that first decodes the four highest bits of the 32-bit address bus and defines three separate areas: one 256-mbyte address space for the internal memories one 256-mbyte address space reserved for the embedded peripherals an undefined address space of 3584m bytes representing fourteen 256-mbyte areas that return an abort if accessed figure 19-2 shows the assignment of the 256-mbyte memory areas. figure 19-2. memory areas 0x0000 0000 0x0fff ffff 0x1000 0000 0xefff ffff 0xf000 0000 0xffff ffff 256m bytes 256m bytes 14 x 256mbytes 3,584 mbytes internal memories undefined (abort) peripherals
91 6042e?atarm?14-dec-06 at91sam7a3 preliminary 19.3.2.1 internal memory mapping within the internal memory address space, the address decoder of the memory controller decodes eight more address bits to allocate 1-mbyte address spaces for the embedded memories. the allocated memories are accessed all along the 1-mbyte address space and so are repeated n times within this address space, n equaling 1m bytes divided by the size of the memory. when the address of the access is undefined within the internal memory area, the address decoder returns an abort to the master. figure 19-3. internal memory mapping 19.3.2.2 internal memory area 0 the first 32 bytes of internal memory area 0 contain the arm processor exception vectors, in particular, the reset vector at address 0x0. before execution of the remap command, the on-chip flash is mapped into internal memory area 0, so that the arm7tdmi reaches an executable instruction contained in flash. after the remap command, the internal sram at address 0x0020 0000 is mapped into internal memory area 0. the memory mapped into internal memory area 0 is accessible in both its original location and at address 0x0. 19.3.3 remap command after execution, the remap command causes the internal sram to be accessed through the internal memory area 0. as the arm vectors (reset, abort, data abort, prefetch abort, undefined instruction, inter- rupt, and fast interrupt) are mapped from address 0x0 to address 0x20, the remap command allows the user to redefine dynamically these vectors under software control. the remap command is accessible through the memo ry controller user interface by writing the mc_rcr (remap control re gister) rcb field to one. the remap command can be cancelled by writing the mc_rcr rcb field to one, which acts as a toggling command. this allows easy debug of the user-defined boot sequence by offering a simple way to put the chip in the same configuration as after a reset. 256m bytes internal memory area 0 undefined areas (abort) 0x0000 0000 0x000f ffff 0x0010 0000 0x001f ffff 0x0020 0000 0x002f ffff 0x0fff ffff 1m bytes 1m bytes 1m bytes 253m bytes internal memory area 1 internal flash internal memory area 2 internal sram 0x0030 0000
92 6042e?atarm?14-dec-06 at91sam7a3 preliminary 19.3.4 abort status there are three reasons for an abort to occur: access to an undefined address access to a protected area without the permitted state an access to a misaligned address. when an abort occurs, a signal is sent back to all the masters, regardless of which one has generated the access. however, only the arm7tdmi can take an abort signal into account, and only under the condition that it was generating an access. the peripheral data controller does not handle the abort input signal. note that the connection is not represented in figure 19-1 . to facilitate debug or for fault analysis by an operating system, the memory controller inte- grates an abort status register set. the full 32-bit wide abort address is saved in mc_aasr. parameters of the access are saved in mc_asr and include: the size of the request (field abtsz) the type of the access, whether it is a data read or write, or a code fetch (field abttyp) whether the access is due to accessing an undefined address (bit undadd), a misaligned address (bit misadd) or a protection violation (bit mpu) the source of the access leading to the last abort (bits mst0 and mst1) whether or not an abort occurred for each master since the last read of the register (bit svmst0 and svmst1) unless this information is loaded in mst bits in the case of a data abort from the processor, the address of the data access is stored. this is useful, as searching for which address gener ated the abort would require disassembling the instructions and full knowledge of the processor context. in the case of a prefetch abort, the address may have changed, as the prefetch abort is pipe- lined in the arm processor. the arm processor takes the prefetch abort into account only if the read instruction is executed and it is probable that several aborts have occurred during this time. thus, in this case, it is preferable to use the content of the abort link register of the arm processor. 19.3.5 memory protection unit the memory protection unit allows definition of up to 16 memory spaces within the internal memories. after reset, the memory protection unit is disabl ed. enabling it requires writing the protection unit enable register (mc_puer) with the pueb at 1. programming of the 16 memory spaces is done in the registers mc_puia0 to mc_puia15. the size of each of the memory spaces is programmable by a power of 2 between 1k bytes and 4m bytes. the base address is also programmable on a number of bits according to the size. the memory protection unit also allows the protection of the peripherals by programming the protection unit peripheral register (mc_pup) with the field prot at the appropriate value.
93 6042e?atarm?14-dec-06 at91sam7a3 preliminary the peripheral address space and each internal memory area can be protected against write and non-privileged access of one of the masters. when one of the masters performs a forbid- den access, an abort is generated and the abort status traces what has happened. there is no priority in the protection of the memory spaces. in case of overlap between several memory spaces, the strongest protection is taken into account. if an access is performed to an address which is not contained in any of the 16 memory spaces, the memory protection unit generates an abort. to prevent this, the user can define a memory space of 4m bytes starting at 0 and authorizing any access. 19.3.6 embedded flash controller the embedded flash controller is added to the memory controller and ensures the interface of the flash block with the 32-bit internal bus. it allows an increase of performance in thumb mode for code fetch with its system of 32-bit buffers. it also manages with the programming, erasing, locking and unlocking sequences thanks to a full set of commands. 19.3.7 misalignment detector the memory controller features a misalignment detector that checks the consistency of the accesses. for each access, regardless of the master, the size of the access and the bits 0 and 1 of the address bus are checked. if the type of access is a word (32-bit) and the bits 0 and 1 are not 0, or if the type of the access is a half-word (16-bit) and the bit 0 is not 0, an abort is returned to the master and the access is cancelled. note that the accesses of the arm processor when it is fetching instructions are not checked. the misalignments are generally due to softwa re bugs leading to wrong pointer handling. these bugs are particularly difficu lt to detect in the debug phase. as the requested address is saved in the abort status register and the address of the instruc- tion generating the misalignment is saved in the abort link register of the processor, detection and fix of this kind of software bugs is simplified.
94 6042e?atarm?14-dec-06 at91sam7a3 preliminary 19.4 memory controller (mc) user interface base address : 0xffffff00 table 19-1. memory controller (mc) memory mapping offset register name access reset state 0x00 mc remap control register mc_rcr write-only 0x04 mc abort status register mc_asr read-only 0x0 0x08 mc abort address status register mc_aasr read-only 0x0 0x0c reserved 0x10 mc protection unit area 0 mc_puia0 read/write 0x0 0x14 mc protection unit area 1 mc_puia1 read/write 0x0 0x18 mc protection unit area 2 mc_puia2 read/write 0x0 0x1c mc protection unit area 3 mc_puia3 read/write 0x0 0x20 mc protection unit area 4 mc_puia4 read/write 0x0 0x24 mc protection unit area 5 mc_puia5 read/write 0x0 0x28 mc protection unit area 6 mc_puia6 read/write 0x0 0x2c mc protection unit area 7 mc_puia7 read/write 0x0 0x30 mc protection unit area 8 mc_puia8 read/write 0x0 0x34 mc protection unit area 9 mc_puia9 read/write 0x0 0x38 mc protection unit area 10 mc_puia10 read/write 0x0 0x3c mc protection unit area 11 mc_puia11 read/write 0x0 0x40 mc protection unit area 12 mc_puia12 read/write 0x0 0x44 mc protection unit area 13 mc_puia13 read/write 0x0 0x48 mc protection unit area 14 mc_puia14 read/write 0x0 0x4c mc protection unit area 15 mc_puia15 read/write 0x0 0x50 mc protection unit peripherals mc_pup read/write 0x0 0x54 mc protection unit enable register mc_puer read/write 0x0 0x60 efc configuration registers see efc part
95 6042e?atarm?14-dec-06 at91sam7a3 preliminary 19.4.1 mc remap control register register name :mc_rcr access type : write-only absolute address : 0xffff ff00 rcb: remap command bit 0: no effect. 1: this command bit acts on a toggle basis: writing a 1 altern atively cancels and restores the remapping of the page zero memory devices. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ???????? 76543210 ???????rcb
96 6042e?atarm?14-dec-06 at91sam7a3 preliminary 19.4.2 mc abort status register register name :mc_asr access type : read-only reset value :0x0 absolute address : 0xffff ff04 undadd: undefined address abort status 0: the last abort was not due to the access of an undefined address in the address space. 1: the last abort was due to the access of an undefined address in the address space. misadd: misaligned address abort status 0: the last aborted access was not due to an address misalignment. 1: the last aborted access was due to an address misalignment. mpu: memory protection unit abort status 0: the last aborted access was not due to the memory protection unit. 1: the last aborted access was due to the memory protection unit. abtsz: abort size status abttyp: abort type status mst0: pdc abort source 0: the last aborted access was not due to the pdc. 1: the last aborted access was due to the pdc. 31 30 29 28 27 26 25 24 ??????svmst1svmst0 23 22 21 20 19 18 17 16 ??????mst1mst0 15 14 13 12 11 10 9 8 ? ? ? ? abttyp abtsz 76543210 ?????mpumisaddundadd abtsz abort size 00 byte 0 1 half-word 10 word 11 reserved abttyp abort type 0 0 data read 0 1 data write 1 0 code fetch 11 reserved
97 6042e?atarm?14-dec-06 at91sam7a3 preliminary mst1: arm7tdmi abort source 0: the last aborted access was not due to the arm7tdmi. 1: the last aborted access was due to the arm7tdmi. svmst0: saved pdc abort source 0: no abort due to the pdc occurred. 1: at least one abort due to the pdc occurred. svmst1: saved arm7tdmi abort source 0: no abort due to the arm7tdmi occurred. 1: at least one abort due to the arm7tdmi occurred. 19.4.3 mc abort address status register register name : mc_aasr access type : read-only reset value :0x0 absolute address : 0xffff ff08 abtadd: abort address this field contains the address of the last aborted access. 31 30 29 28 27 26 25 24 abtadd 23 22 21 20 19 18 17 16 abtadd 15 14 13 12 11 10 9 8 abtadd 76543210 abtadd
98 6042e?atarm?14-dec-06 at91sam7a3 preliminary 19.4.4 mc protection unit area 0 to 15 registers register name : mc_puia0 - mc_puia15 access type : read/write reset value :0x0 absolute address : 0xffffff10 - 0xffffff4c prot: protection: size: internal area size ba: internal area base address these bits define the base address of the area. note that only th e most significant bits of ba are significant. the number of significant bits are in respect with the size of the area. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ?? ba 15 14 13 12 11 10 9 8 ba ? ? 76543210 size ? ? prot prot processor mode privilege user 0 0 no access no access 0 1 read/write no access 1 0 read/write read-only 1 1 read/write read/write size area size lsb of ba 0000 1 kb 10 0001 2 kb 11 0010 4 kb 12 0011 8 kb 13 010016 kb 14 010132 kb 15 011064 kb 16 0111128 kb 17 1000256 kb 18 1001512 kb 19 10101 mb 20 10112 mb 21 11014 mb 22
99 6042e?atarm?14-dec-06 at91sam7a3 preliminary 19.4.5 mc protection unit peripheral register name :mc_pup access type : read/write reset value : 0x000000000 absolute address : 0xffffff50 prot: protection 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ???????? 76543210 ?????? prot prot processor mode privilege user 0 0 read/write no access 0 1 read/write no access 1 0 read/write read-only 1 1 read/write read/write
100 6042e?atarm?14-dec-06 at91sam7a3 preliminary 19.4.6 mc protection unit enable register register name :mc_puer access type : read/write reset value : 0x000000000 absolute address : 0xffffff54 pueb: protection unit enable bit 0: the memory controller protection unit is disabled. 1: the memory controller protection unit is enabled. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ???????? 76543210 ???????pueb
101 6042e?atarm?14-dec-06 at91sam7a3 preliminary 20. embedded flash controller (efc) 20.1 overview the embedded flash controller is added to the memory controller and ensures the interface of the flash block with the 32-bit internal bus. it increases performance in thumb mode for code fetch with its system of 32-bit buffers. it also manages the programming, erasing, lock- ing and unlocking sequences using a full set of commands. 20.2 functional description 20.2.1 embedded flash organization the embedded flash interfaces directly to the 32-bit internal bus. it is composed of several interfaces: one memory plane organized in several pages of the same size. two 32-bit read buffers used for code read optimization (see ?read operations? on page 102 ). one write buffer that manages page programming. the write buffer size is equal to the page size. this buffer is write-only and accessible all along the 1 mbyte address space, so that each word can be written to its final address (see ?write operations? on page 104 ). several lock bits used to protect write and erase operations on lock regions. a lock region is composed of several consecutive pages, and each lock region has its associated lock bit. the embedded flash size, the page size and the lo ck region organization are described in the product definition section.
102 6042e?atarm?14-dec-06 at91sam7a3 preliminary figure 20-1. embedded flash memory mapping 20.2.2 read operations an optimized controller manages embedded flash reads. a system of 2 x 32-bit buffers is added in order to start access at following address during the second read, thus increasing performance when the processor is running in thumb mode (16-bit instruction set). see fig- ure 20-2 , figure 20-3 and figure 20-4 . this optimization concerns only code fetch and not data. the read operations can be performed with or without wait state. up to 3 wait states can be programmed in the field fws (flash wait state) in the flash mode register mc_fmr (see ?mc flash mode register? on page 110 ). defining fws to be 0 enables the single-cycle access of the embedded flash. the flash memory is accessible through 8-, 16- and 32-bit reads. as the flash block size is smaller than the address space reserved for the internal memory area, the embedded flash wraps around the address space and appears to be repeated within it. lock region 0 lock region (n-1) locked region area page 0 page (m-1) start address unlockable area 32 bits wide flash memory start address + flash size -1 page ( (n-1)*m ) page (n*m-1) lock bit 0 lock region 1 lock bit 1 lock bit n-1
103 6042e?atarm?14-dec-06 at91sam7a3 preliminary figure 20-2. code read optimization in thumb mode for fws = 0 note: when fws is equal to 0, all accesse s are performed in a single-cycle access . figure 20-3. code read optimization in thumb mode for fws = 1 note: when fws is equal to 1, in case of sequential re ads, all the accesses are performed in a single-cycle access (except for t he first one). flash access buffer (32 bits) master clock arm request (16-bit) code fetch data to arm bytes 0-3 bytes 4-7 bytes 0-3 bytes 0-1 bytes 2-3 bytes 4-5 bytes 6-7 bytes 8-9 bytes 10-11 bytes 12-13 @byte 0 @byte 2 @byte 4 @byte 6 @byte 8 @byte 10 @byte 12 @byte 14 @byte 16 bytes 14-15 bytes 4-7 bytes 8-11 bytes 8-11 bytes 12-15 bytes 16-19 bytes 12-15 flash access buffer (32 bits) master clock arm request (16-bit) code fetch data to arm bytes 0-3 bytes 4-7 bytes 0-3 bytes 2-3 bytes 4-5 bytes 6-7 bytes 8-9 bytes 10-11 @byte 0 @byte 4 @byte 6 @byte 8 @byte 10 @byte 12 @byte 14 bytes 4-7 bytes 8-11 bytes 8-11 bytes 12-15 1 wait state cycle bytes 0-1 1 wait state cycle 1 wait state cycle 1 wait state cycle @byte 2 bytes 12-13
104 6042e?atarm?14-dec-06 at91sam7a3 preliminary figure 20-4. code read optimization in thumb mode for fws = 3 note: when fws is equal to 2 or 3, in case of sequential r eads, the first access takes fws cycles, the second access one cycle, the third access fws cycles, the fourth access one cycle, etc. 20.2.3 write operations the internal memory area reserved for the embedded flash can also be written through a write-only latch buffer. write operations take into account only the 8 lowest address bits and thus wrap around within the internal memory area address space and appear to be repeated 1024 times within it. write operations might be prevented by programming the memory protection unit of the product. writing of 8-bit and 16-bit data is not allowed and may lead to unpredictable data corruption. write operations are performed in the number of wait states equal to the number of wait states for read operations + 1, except for fws = 3 (see ?mc flash mode register? on page 110 ). 20.2.4 flash commands the embedded flash controller offers a command set to manage programming the memory flash, locking and unlocking lock regions, cons ecutive programming and locking, and full flash erasing. in order to perform one of these commands, the flash command register (mc_fcr) has to be written with the correct command using to the field fcmd (see ?mc flash command reg- ister? on page 112 ). flash access master clock data to arm 0-1 @byte 0 @2 bytes 0-3 bytes 4-7 bytes 8-11 bytes 12-15 bytes 0-3 2-3 6-7 @4 8-9 10-11 4-5 @8 @12 bytes 4-7 3 wait state cycles buffer (32 bits) arm request (16-bit) code fetch bytes 8-11 3 wait state cycles 3 wait state cycles 3 wait state cycles @6 @10 12-13 table 20-1. set of commands command value mnemonic write page 0x01 wp set lock bit 0x02 slb write page and lock 0x03 wpl clear lock bit 0x04 clb erase all 0x08 ea
105 6042e?atarm?14-dec-06 at91sam7a3 preliminary all the commands are protected by the same ke yword, which has to be written in the eight highest bits of the mc_fcr register. writing mc_fcr with data that does not contain the correct key and/or with an invalid com- mand has no effect on the memory plane; however, the proge flag is set in the mc_fsr register. this flag is automatically cleared by a read access to the mc_fsr register. when the current command writes or erases a page in a locked region, the command has no effect on the whole memory pl ane; however, the locke flag is set in the mc_fsr register. this flag is automatically cleared by a read access to the mc_fsr register. in order to guarantee valid operations on the flash memory, the field flash microsecond cycle number (fmcn) in the flash mode register mc_fmr must be correctly programmed (see ?mc flash mode register? on page 110 ). 20.2.4.1 programming the programming is done by writing data into the latch buffer and then triggering a program- ming command that corresponds to the write page command (wp) in the flash command register mc_fcr. the sequence is as follows: write the full page, at any page address, within the internal memory area address space using only 32-bit access. if not already done, set the bit eop (end of programming) in the flash mode register, depending on whether an interrupt is required or not at the end of programming. write in the field pagen of the flash command register (mc_fcr) the page number to be programmed. clear the bit nebp (no erase before pr ogramming) in mc_fmr, if an erase before programming is required. start the programming by writing the flash command register with the write page command. the page defined by pagen is first erased if the bit nebp is set to 0 and then programmed with the data written in the buffer. when the programming completes, the bit eop in the flash programming status register raises. if an interrupt has been enabled by setting the bit eop in mc_fmr, the interrupt line of the memory controller is activated. figure 20-5. state of the eop bit in mc_fsr when the software reads the flash status regi ster (mc_fsr), the eop bit is automatically cleared and the interrupt line is deactivated. programming time read the mc_fsr write the mc_fcr with wp or wpl command eop
106 6042e?atarm?14-dec-06 at91sam7a3 preliminary two errors can be detected in the mc_fsr register after a programming sequence: programming error: a bad keyword and/or an invalid command have been written in the mc_fcr register. lock error: the page to be programmed belongs to a locked region. a command must be previously run to unlock the corresponding region. the flash technology requires that an erase must be done before programming. the entire memory plane can be erased at the same time, or a page can be automatically erased by clearing the nebp bit in the mc_fmr register before writing the command in the mc_fcr register. by setting the nebp bit in the mc_fmr register, a p age can be pr ogrammed in several steps if it has been erased before (see figure 20-6 ). figure 20-6. example of partial page programming: 20.2.4.2 lock and unlock operations lock bits are associated with several pages in the embedded flash memory plane. this defines lock regions in the embedded flash memory plane. they prevent writing/erasing pro- tected pages. each lock region has its own lock bit that is readable in the highest bits of the flash status register (mc_fsr). after production, the device may have some embedded flash lock regions locked. these locked regions are reserved for a default application. refer to the product definition section for the default embedded flash mapping. locked lock regions can be unlocked to be erased and then programmed with another application or other data. the lock and unlock commands are performed by defining the pagen field and by writing the appropriate command ( set lock bit command (slb) or clear lock bit command (clb) ) in the flash command register (mc_fcr) . pagen defines one page number of the lock region to be locked or unlocked. writing in all the other bits of pagen has no effect. erase all flash programming of the second part of page 7 programming of the third part of page 7 32 bits wide 32 bits wide 32 bits wide 16 words ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ... ca fe ca fe ca fe ca fe ca fe ca fe ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ca fe ca fe ca fe ca fe ca fe ca fe de ca de ca de ca de ca de ca de ca ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff step 1. step 2. step 3. ... ... ... ... ... ... ... ... ... ... ... (nebp = 1) (nebp = 1) 16 words 16 words 16 words page 7 erased
107 6042e?atarm?14-dec-06 at91sam7a3 preliminary the clear lock bit command programs the lock bit to 1; the corresponding bit locksx in mc_fsr reads 0. the set lock bit command progra ms the lock bit to 0; the corresponding bit locksx in mc_fsr reads 1. when the set lock bit or clear lock bit command is triggered, the programming or erasing operation of the lock bit is performed. when it completes, the bit eol is set. no access to the flash is permitted when a set lock bit or clear lock bit command is performed. a programming error, where a bad keyword and/or an invalid command have been written in the mc_fcr register, may be detected in the mc_fsr register after a programming sequence. figure 20-7. state of the eol bit in mc_fsr 20.2.4.3 lock protection when a programming command is performed with pagen defining a locked lock region, the bit locke in mc_fsr rises. if the bit locke has been written at 1 in mc_fmr, the interrupt line rises. reading mc_fsr automatically clears the bit locke in mc_fsr and thus deacti- vates the interrupt line. 20.2.4.4 write page and lock the user can perform consecutively the programming of the page and the lock of the lock region ( write page and lock command (wpl) in the fcmd field of the flash command register mc_fcr), both defined by pagen. only one or both end of programming or end of lock interrupts may be enabled to trigger an interrupt when the operations completes. 20.2.4.5 erase all flash the entire memory can be erased if the erase all command (ea) in the flash command register mc_fcr is written. erase all operation is allowed only if there are no lock bits set. thus, if at least one lock region is locked, the bit locke in mc_fsr rises and the command is cancelled. if the bit locke has been written at 1 in mc_fmr, the interrupt line rises (see ?lock protection? on page 107 ). if not already done, set the bit eop (end of programming) in the flash mode register, depending on whether an interrupt is required or not at the end of the erase. when the flash erase is complete, the bit eop in the flash programming status register rises. if an interrupt has been enabled by setting the bit eop in mc_fmr, the interrupt line of the memory controller is activated. locking or unlocking time sequence read the mc_fsr write the mc_fcr with slb, clb or wpl command eol
108 6042e?atarm?14-dec-06 at91sam7a3 preliminary when the software reads the flash status regi ster (mc_fsr), the eop bit is automatically cleared and the interrupt line is deactivated. two errors can be detected in the mc_fsr register after a programming sequence: programming error: a bad keyword and/or an invalid command have been written in the mc_fcr register. lock error: at least one lock region to be erased is protected. the erase command has been refused and no page has been erased. a clear lock bit command must be executed previously to unlock the corresponding lock regions.
109 6042e?atarm?14-dec-06 at91sam7a3 preliminary 20.3 embedded flash controll er (efc) user interface the user interface of the embedded flash controller is integrated within the memory controller with base address: 0xffff ff00. table 20-2. embedded flash controller (efc) register mapping offset register name access reset state 0x60 mc flash mode register mc_fmr read/write 0x0 0x64 mc flash command register mc_fcr write-only ? 0x68 mc flash status register mc_fsr read-only ? 0x6c reserved ? ? ?
110 6042e?atarm?14-dec-06 at91sam7a3 preliminary 20.3.1 mc flash mode register register name :mc_fmr access type : read/write offset :0x60 eop: end of programming interrupt enable 0: end of programming (page programming or erase all flash) does not generate an interrupt. 1: end of programming (page programming or erase all flash) generates an interrupt. eol: end of lock/unlock interrupt enable 0: end of lock or end of unlock does not generate an interrupt. 1: end of lock or end of unlock generates an interrupt. locke: lock error interrupt enable 0: lock error does not generate an interrupt. 1: lock error generates an interrupt. proge: programming error interrupt enable 0: programming error does not generate an interrupt. 1: programming error generates an interrupt. nebp: no erase before programming 0: a page erase is performed before programming. 1: no erase is performed before programming. fws: flash wait state this field defines the number of wait states for read and write operations: 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 fmcn 15 14 13 12 11 10 9 8 ?????? fws 76543210 nebp ? ? ? proge locke eol eop fws read operations write operations 0 1 cycle 2 cycles 1 2 cycles 3 cycles 2 3 cycles 4 cycles 3 4 cycles 4 cycles
111 6042e?atarm?14-dec-06 at91sam7a3 preliminary fmcn: flash microsecond cycle number before writing lock bits, this field must be set to the number of master clock cycles in one hundred nanoseconds. when writing the rest of the flash, this field defines the numb er of master clock cycles in 1.5 microseconds. this number must be rounded up. warning : the value 0 is only allowed for a master clock period superior to 30 microseconds. warning: in order to guarantee valid operations on the flash me mory, the field flash microsecond cycle number (fmcn) must be correctly programmed.
112 6042e?atarm?14-dec-06 at91sam7a3 preliminary 20.3.2 mc flash command register register name :mc_fcr access type :write only offset :0x64 fcmd: flash command this field defines the flash commands: 31 30 29 28 27 26 25 24 key 23 22 21 20 19 18 17 16 ?????? pagen 15 14 13 12 11 10 9 8 pag e n 76543210 ???? fcmd fcmd operations 0000 no command. does not raise the programming error status flag in the flash status register mc_fsr. 0001 write page command (wp): starts the programming of the page specified in the pagen field. 0010 set lock bit command (slb): starts a set lock bit sequence of the lo ck region specified in the pagen field. 0011 write page and lock command (wpl): the lock sequence of the lock region associated with the page specified in the field pagen occurs automatically after completion of the programming sequence . 0100 clear lock bit command (clb): starts a clear lock bit sequence of the lock region specified in the pagen field. 1000 erase all command (ea): starts the erase of the entire flash. if at least one page is locked, the command is cancelled. others reserved. raises the programming error status flag in the flash status register mc_fsr.
113 6042e?atarm?14-dec-06 at91sam7a3 preliminary pagen: page number note: depending on the command, all the possible unused bits of pagen are meaningless. key: writing protection key this field should be written with the value 0x5a to enable the command defined by the bits of the register. if the field is wri t- ten with a different value, the write is actually not performed and no action is started. command pagen description write page command pagen defines the page number to be written. write page and lock command pagen defines the page number to be written and its associated lock region. erase all command this field is meaningless set/clear lock bit command pagen defines one page number of the lock region to be locked or unlocked.
114 6042e?atarm?14-dec-06 at91sam7a3 preliminary 20.3.3 mc flash status register register name :mc_fsr access type : read only offset :0x68 eop: end of programming status 0: the programming sequence (page programming or erase all flash) triggered by the last write in mc_fcr is not yet completed, or fmc_fsr has been read. 1: the programming sequence (page programming or erase all flash) triggered by the last write in mc_fcr is completed and mc_fsr has not been read yet. eol: end of lock status 0: the lock or unlock sequence triggered by the last write in mc_fcr is not yet completed, or fmc_fsr has been read. 1: the lock or unlock sequence triggered by the last writ e in mc_fcr is completed and mc_fsr has not been read yet. locke: lock error status 0: no programming of at least one locked lock region has happened since the last read of mc_fsr. 1: programming of at least one locked lock regi on has happened since the last read of mc_fsr. proge: programming error status 0: no invalid commands and no bad key-words were written in the flash command register mc_fcr. 1: an invalid command and/or a bad key-word was/were written in the flash command register mc_fcr. locksx: lock region x lock status 0: the corresponding lock region is not locked. 1: the corresponding lock region is locked. 31 30 29 28 27 26 25 24 locks15 locks14 locks13 locks12 locks11 locks10 locks9 locks8 23 22 21 20 19 18 17 16 locks7 locks6 locks5 locks4 locks3 locks2 locks1 locks0 15 14 13 12 11 10 9 8 ???????? 76543210 ? ? ? ? proge locke eol eop
115 6042e?atarm?14-dec-06 at91sam7a3 preliminary 21. peripheral dma controller (pdc) 21.1 overview the peripheral dma controller (pdc) transfer s data between on-chip serial peripherals such as the uart, usart, ssc, spi, mci and the on- and off-chip memories. using the periph- eral dma controller avoids processor intervention and removes the processor interrupt- handling overhead. this significantly reduces the number of clock cycles required for a data transfer and, as a result, improves the performance of the microcontroller and makes it more power efficient. the pdc channels are implemented in pairs, each pair being dedicated to a particular periph- eral. one channel in the pair is dedicated to the receiving channel and one to the transmitting channel of each uart, usart, ssc and spi. the user interface of a pdc channel is integrat ed in the memory space of each peripheral. it contains: two 32-bit memory pointer registers (send and receive) two 16-bit transfer count registers (send and receive) two 32-bit registers for next memory pointer (send and receive) two 16-bit registers for next transfer count (send and receive) the peripheral triggers pdc transfers usi ng transmit and receive signals. when the pro- grammed data is transferred, an end of transfer interrupt is generated by the corresponding peripheral. 21.2 block diagram figure 21-1. block diagram control pdc channel 0 pdc channel 1 thr rhr control status & control peripheral peripheral dma controller memory controller
116 6042e?atarm?14-dec-06 at91sam7a3 preliminary 21.3 functional description 21.3.1 configuration the pdc channels user interface enables the user to configure and control the data transfers for each channel. the user interface of a pdc c hannel is integrated into the user interface of the peripheral (offset 0x100), which it is related to. per peripheral, it contains four 32-bit pointer registers (rpr, rnpr, tpr, and tnpr) and four 16-bit counter registers (rcr, rncr, tcr, and tncr). the size of the buffer (number of transfers) is configured in an internal 16-bit transfer counter register, and it is possible, at any moment, to read the number of transfers left for each channel. the memory base address is configured in a 32-bit memory pointer by defining the location of the first address to access in the memory. it is possible, at any moment, to read the location in memory of the next transfer and the number of remaining transfers. the pdc has dedicated status registers which indicate if the transfer is enabled or disabled for each channel. the sta- tus for each channel is located in the peripheral status register. transfers can be enabled and/or disabled by setting txten/txtdis and rxten/rxtdis in pdc transfer control register. these control bits enable reading the pointer and counter registers safely without any risk of their changing between both reads. the pdc sends status flags to the peripheral visible in its status-register (endrx, endtx, rxbuff, and txbufe). endrx flag is set when the periph_rcr register reaches zero. rxbuff flag is set when both pe riph_rcr and periph_rncr reach zero. endtx flag is set when the per iph_tcr register reaches zero. txbufe flag is set when both pe riph_tcr and periph_tncr reach zero. these status flags are described in the peripheral status register. 21.3.2 memory pointers each peripheral is connected to the pdc by a receiver data channel and a transmitter data channel. each channel has an internal 32-bit memory pointer. each memory pointer points to a location anywhere in the memory space (on-ch ip memory or external bus interface memory). depending on the type of transfer (byte, half-word or word), the memory pointer is incre- mented by 1, 2 or 4, respectively for peripheral transfers. if a memory pointer is reprogrammed while the pdc is in operation, the transfer address is changed, and the pdc performs transfers using the new address. 21.3.3 transfer counters there is one internal 16-bit transfer counter for each channel used to count the size of the block already transferred by its associated channel. these counters are decremented after each data transfer. when the counter reaches zero, the transfer is complete and the pdc stops transferring data. if the next counter register is equal to zero, the pdc disables the trigger while activating the related peripheral end flag.
117 6042e?atarm?14-dec-06 at91sam7a3 preliminary if the counter is reprogrammed while the pdc is operating, the number of transfers is updated and the pdc counts transfers from the new value. programming the next counter/pointer registers chains the buffers. the counters are decre- mented after each data transfer as stated above, but when the transfer counter reaches zero, the values of the next counter/pointer are loaded into the counter/pointer registers in order to re-enable the triggers. for each channel, two status bits indicate the end of the current buffer (endrx, endtx) and the end of both current and next buffer (rxbuff, txbufe). these bits are directly mapped to the peripheral status register and can trigger an interrupt request to the aic. the peripheral end flag is automatically cleared when one of the counter-registers (counter or next counter regi ster) is written. note: when the next counter register is loaded into the counter register, it is set to zero. 21.3.4 data transfers the peripheral triggers pdc transfers using transmit (txrdy) and receive (rxrdy) signals. when the peripheral receives an external charac ter, it sends a receive ready signal to the pdc which then requests access to the system bus. when access is granted, the pdc starts a read of the peripheral receive holding regi ster (rhr) and then triggers a write in the memory. after each transfer, the relevant pdc memory pointer is incremented and the number of trans- fers left is decremented. when the memory bl ock size is reached, a signal is sent to the peripheral and the transfer stops. the same procedure is followed, in reverse, for transmit transfers. 21.3.5 priority of pdc transfer requests the peripheral dma controller handles transfer requests from the channel according to priori- ties fixed for each product.these prioriti es are defined in the product datasheet. if simultaneous requests of the same type (receiver or transmitter) occur on identical peripher- als, the priority is determined by the numbering of the peripherals. if transfer requests are not simultaneous, they are treated in the order they occurred. requests from the receivers are handled first and then followed by transmitter requests.
118 6042e?atarm?14-dec-06 at91sam7a3 preliminary 21.4 peripheral dma controll er (pdc) user interface note: 1. periph: ten registers are mapped in the peripheral memory space at the same offset. these can be defined by the user according to the function and the peripheral desired (dbgu, usart, ssc, spi, mci etc). table 21-1. register mapping offset register register name read/write reset 0x100 receive pointer register periph (1) _rpr read/write 0x0 0x104 receive counter register periph_rcr read/write 0x0 0x108 transmit pointer register periph_tpr read/write 0x0 0x10c transmit counter register periph_tcr read/write 0x0 0x110 receive next pointer register periph_rnpr read/write 0x0 0x114 receive next counter register periph_rncr read/write 0x0 0x118 transmit next pointer register periph_tnpr read/write 0x0 0x11c transmit next counter register periph_tncr read/write 0x0 0x120 pdc transfer control register periph_ptcr write-only - 0x124 pdc transfer status r egister periph_ptsr read-only 0x0
119 6042e?atarm?14-dec-06 at91sam7a3 preliminary 21.4.1 pdc receive pointer register register name: periph _ rpr access type: read/write rxptr: receive pointer address address of the next receive transfer. 21.4.2 pdc receive counter register register name: periph _ rcr access type: read/write rxctr: receive counter value number of receive transfers to be performed. 31 30 29 28 27 26 25 24 rxptr 23 22 21 20 19 18 17 16 rxptr 15 14 13 12 11 10 9 8 rxptr 76543210 rxptr 31 30 29 28 27 26 25 24 -- 23 22 21 20 19 18 17 16 -- 15 14 13 12 11 10 9 8 rxctr 76543210 rxctr
120 6042e?atarm?14-dec-06 at91sam7a3 preliminary 21.4.3 pdc transmit pointer register register name: periph _ tpr access type: read/write txptr: transmit pointer address address of the transmit buffer. 21.4.4 pdc transmit counter register register name: periph _ tcr access type: read/write txctr: transmit counter value txctr is the size of the transmit transfer to be performed. at zero, the peripheral data transfer is stopped. 31 30 29 28 27 26 25 24 txptr 23 22 21 20 19 18 17 16 txptr 15 14 13 12 11 10 9 8 txptr 76543210 txptr 31 30 29 28 27 26 25 24 -- 23 22 21 20 19 18 17 16 -- 15 14 13 12 11 10 9 8 txctr 76543210 txctr
121 6042e?atarm?14-dec-06 at91sam7a3 preliminary 21.4.5 pdc receive next pointer register register name: periph _ rnpr access type: read/write rxnptr: receive next pointer address rxnptr is the address of the next buffer to fill with received data when th e current buffer is full. 21.4.6 pdc receive next counter register register name: periph _ rncr access type: read/write rxncr: receive next counter value rxncr is the size of the next buffer to receive. 31 30 29 28 27 26 25 24 rxnptr 23 22 21 20 19 18 17 16 rxnptr 15 14 13 12 11 10 9 8 rxnptr 76543210 rxnptr 31 30 29 28 27 26 25 24 -- 23 22 21 20 19 18 17 16 -- 15 14 13 12 11 10 9 8 rxncr 76543210 rxncr
122 6042e?atarm?14-dec-06 at91sam7a3 preliminary 21.4.7 pdc transmit next pointer register register name: periph _ tnpr access type: read/write txnptr: transmit next pointer address txnptr is the address of the next buffer to transmit when the current buffer is empty. 21.4.8 pdc transmit next counter register register name: periph _ tncr access type: read/write txncr: transmit next counter value txncr is the size of the next buffer to transmit. 31 30 29 28 27 26 25 24 txnptr 23 22 21 20 19 18 17 16 txnptr 15 14 13 12 11 10 9 8 txnptr 76543210 txnptr 31 30 29 28 27 26 25 24 -- 23 22 21 20 19 18 17 16 -- 15 14 13 12 11 10 9 8 txncr 76543210 txncr
123 6042e?atarm?14-dec-06 at91sam7a3 preliminary 21.4.9 pdc transfer control register register name: periph_ptcr access type: write - only rxten: receiver transfer enable 0 = no effect. 1 = enables the receiver pdc transfer requests if rxtdis is not set. rxtdis: receiver transfer disable 0 = no effect. 1 = disables the receiver pdc transfer requests. txten: transmitter transfer enable 0 = no effect. 1 = enables the transmitter pdc transfer requests. txtdis: transmitter transfer disable 0 = no effect. 1 = disables the transmitter pdc transfer requests 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ??????txtdistxten 76543210 ??????rxtdisrxten
124 6042e?atarm?14-dec-06 at91sam7a3 preliminary 21.4.10 pdc transfer status register register name: periph _ ptsr access type: read-only rxten: receiver transfer enable 0 = receiver pdc transfer requests are disabled. 1 = receiver pdc transfer requests are enabled. txten: transmitter transfer enable 0 = transmitter pdc transfer requests are disabled. 1 = transmitter pdc transfer requests are enabled. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ???????txten 76543210 ???????rxten
125 6042e?atarm?14-dec-06 at91sam7a3 preliminary 22. advanced interrupt controller (aic) 22.1 overview the advanced interrupt controller (aic) is an 8- level priority, individually maskable, vectored interrupt controller, providing handling of up to thirty-two interrupt sources. it is designed to substantially reduce the software and real-time overhead in handling internal and external interrupts. the aic drives the nfiq (fast interrupt request) and the nirq (standard interrupt request) inputs of an arm processor. inputs of the aic are either internal peripheral interrupts or exter- nal interrupts coming from the product's pins. the 8-level priority controller allows the user to define the priority for each interrupt source, thus permitting higher priority interrupts to be serviced even if a lower priority interrupt is being treated. internal interrupt sources can be programmed to be level sensitive or edge triggered. external interrupt sources can be programmed to be positive-edge or negative-edge triggered or high- level or low-level sensitive. the fast forcing feature redirects any internal or external interrupt source to provide a fast interrupt rather than a normal interrupt. 22.2 block diagram figure 22-1. block diagram aic apb arm processor fiq irq0-irqn embedded peripheralee peripheral embedded peripheral embedded up to thirty-two sources nfiq nirq
126 6042e?atarm?14-dec-06 at91sam7a3 preliminary 22.3 application block diagram figure 22-2. description of the application block 22.4 aic detailed block diagram figure 22-3. aic detailed block diagram 22.5 i/o line description advanced interrupt controller embedded peripherals external peripherals (external interrupts) standalone applications rtos drivers hard real time tasks os-based applications os drivers general os interrupt handler fiq pio controller advanced interrupt controller irq0-irqn pioirq embedded peripherals external source input stage internal source input stage fast forcing interrupt priority controller fast interrupt controller arm processor nfiq nirq power management controller wake up user interface apb processor clock table 22-1. i/o line description pin name pin description type fiq fast interrupt input irq0 - irqn interrupt 0 - interrupt n input
127 6042e?atarm?14-dec-06 at91sam7a3 preliminary 22.6 product dependencies 22.6.1 i/o lines the interrupt signals fiq and irq0 to irqn are normally multiplexed through the pio control- lers. depending on the features of the pio cont roller used in the product, the pins must be programmed in accordance with their assigned inte rrupt function. this is not applicable when the pio controller used in the product is transparent on the input path. 22.6.2 power management the advanced interrupt controller is continuously clocked. the power management controller has no effect on the advanced interrupt controller behavior. the assertion of the advanced interrupt controller outputs, either nirq or nfiq, wakes up the arm processor while it is in idle mode. the general interrupt mask feature enables the aic to wake up the processor without asserting the interrupt line of the processor, thus providing syn- chronization of the processor on an event. 22.6.3 interrupt sources the interrupt source 0 is always located at fiq. if the product does not feature an fiq pin, the interrupt source 0 cannot be used. the interrupt source 1 is always located at syst em interrupt. this is the result of the or-wir- ing of the system peripheral interrupt lines, such as the system timer, the real time clock, the power management controller and the memory controller. when a system interrupt occurs, the service routine must first distinguis h the cause of the interrupt. this is performed by reading successively the status register s of the above mentioned system peripherals. the interrupt sources 2 to 31 can either be connected to the interrupt outputs of an embedded user peripheral or to external interrupt lines. the external interrupt lines can be connected directly, or through the pio controller. the pio controllers are considered as user peripherals in the scope of interrupt handling. accordingly, the pio controller interrupt lines are connected to the interrupt sources 2 to 31. the peripheral identification defined at the pr oduct level corresponds to the interrupt source number (as well as the bit number controlling the clock of the peripheral). consequently, to simplify the description of the functional operations and the user interface, the interrupt sources are named fiq, sys, and pid2 to pid31.
128 6042e?atarm?14-dec-06 at91sam7a3 preliminary 22.7 functional description 22.7.1 interrupt source control 22.7.1.1 interrupt source mode the advanced interrupt controller independently programs each interrupt source. the src- type field of the corresponding aic_smr (source mode register) selects the interrupt condition of each source. the internal interrupt sources wired on the interrupt outputs of the embedded peripherals can be programmed either in level-sensitive mode or in edge-triggered mode. the active level of the internal interrupts is not important for the user. the external interrupt sources can be programmed either in high level-sensitive or low level- sensitive modes, or in positive edge-triggered or negative edge-triggered modes. 22.7.1.2 interrupt source enabling each interrupt source, including the fiq in source 0, can be enabled or disabled by using the command registers; aic_iecr (interrupt enable command register) and aic_idcr (inter- rupt disable command register). this set of registers conducts enabling or disabling in one instruction. the interrupt mask can be read in the aic_imr register. a disabled interrupt does not affect servicing of other interrupts. 22.7.1.3 interrupt clearing and setting all interrupt sources programmed to be edge-triggered (including the fiq in source 0) can be individually set or cleared by writing resp ectively the aic_iscr and aic_iccr registers. clearing or setting interrupt sources programmed in level-sensitive mode has no effect. the clear operation is perfunctory, as the software must perform an action to reinitialize the ?memorization? circuitry activated when the source is programmed in edge-triggered mode. however, the set operation is available for auto-test or software debug purposes. it can also be used to execute an aic-implementation of a software interrupt. the aic features an automatic clear of the current interrupt when the aic_ivr (interrupt vec- tor register) is read. only the interrupt source being detected by the aic as the current interrupt is affected by this operation. ( see ?priority controller? on page 132. ) the automatic clear reduces the operations required by the interrupt service routine entry code to reading the aic_ivr. note that the automatic interrupt clear is disabled if the interrupt source has the fast forcing feature enabled as it is considered un iquely as a fiq source. (for further details, see ?fast forcing? on page 136. ) the automatic clear of the interrupt source 0 is performed when aic_fvr is read. 22.7.1.4 interrupt status for each interrupt, the aic operation originates in aic_ipr (interrupt pending register) and its mask in aic_imr (interrupt mask register). aic_ipr enables the actual activity of the sources, whether masked or not. the aic_isr register reads the number of the current interrupt (see ?priority controller? on page 132 ) and the register aic_cisr gives an image of the signals nirq and nfiq driven on the processor. each status referred to above can be used to optimize the interrupt handling of the systems.
129 6042e?atarm?14-dec-06 at91sam7a3 preliminary 22.7.1.5 internal interrupt source input stage figure 22-4. internal interrupt source input stage 22.7.1.6 external interrupt source input stage figure 22-5. external interrupt source input stage edge detector clear set source i aic_ipr aic_imr aic_iecr aic_idcr aic_iscr aic_iccr fast interrupt controller or priority controller ff level/ edge aic_smri (srctype) edge detector clear set pos./neg. aic_iscr aic_iccr source i ff level/ edge high/low aic_smri srctype aic_ipr aic_imr aic_iecr aic_idcr fast interrupt controlle r or priority controller
130 6042e?atarm?14-dec-06 at91sam7a3 preliminary 22.7.2 interrupt latencies global interrupt latencies depend on several parameters, including: the time the software masks the interrupts. occurrence, either at the processor level or at the aic level. the execution time of the instruction in progress when the interrupt occurs. the treatment of higher priority interrupts and the resynchronization of the hardware signals. this section addresses only the hardware resynchronizations. it gives details of the latency times between the event on an external interrupt leading in a valid interrupt (edge or level) or the assertion of an internal interrupt source and the assertion of the nirq or nfiq line on the processor. the resynchronization time depends on the programming of the interrupt source and on its type (internal or external). for the standard interrupt, resynchronization times are given assuming there is no higher priority in progress. the pio controller multiplexing has no effect on the interrupt latencies of the external interrupt sources. 22.7.2.1 external interrupt edge triggered source figure 22-6. external interrupt edge triggered source maximum fiq latency = 4 cycles maximum irq latency = 4 cycles nfiq nirq mck irq or fiq (positive edge) irq or fiq (negative edge)
131 6042e?atarm?14-dec-06 at91sam7a3 preliminary 22.7.2.2 external interrupt level sensitive source figure 22-7. external interrupt level sensitive source 22.7.2.3 internal interrupt edge triggered source figure 22-8. internal interrupt edge triggered source 22.7.2.4 internal interrupt level sensitive source figure 22-9. internal interrupt level sensitive source maximum irq latency = 3 cycles maximum fiq latency = 3 cycles mck irq or fiq (high level) irq or fiq (low level) nirq nfiq mck nirq peripheral interrupt becomes active maximum irq latency = 4.5 cycles mck nirq maximum irq latency = 3.5 cycles peripheral interrupt becomes active
132 6042e?atarm?14-dec-06 at91sam7a3 preliminary 22.7.3 normal interrupt 22.7.3.1 priority controller an 8-level priority controller drives the nirq line of the processor, depending on the interrupt conditions occurring on the interrupt sources 1 to 31 (except for those programmed in fast forcing). each interrupt source has a programmable priority level of 7 to 0, whic h is user-definable by writing the prior field of the corresponding aic_smr (source mode register). level 7 is the highest priority and level 0 the lowest. as soon as an interrupt cond ition occurs, as defined by th e srctype field of the aic_smr (source mode register), the nirq line is asserted. as a new interrupt condition might have happened on other interrupt sources since the nirq has been asserted, the priority controller determines the current interrupt at the time the aic_ivr (interrupt vector register) is read. the read of aic_ivr is the entry point of the interrupt handling which allows the aic to consider that the interrupt has been taken into account by the software. the current priority level is defined as the priority level of the current interrupt. if several interrupt sources of equal priority are pending and enabled when the aic_ivr is read, the interrupt with the lowest interrupt source number is serviced first. the nirq line can be asserted only if an interrupt condition occurs on an interrupt source with a higher priority. if an interrupt condition happens (or is pending) during the interrupt treatment in progress, it is delayed until the software indicates to the aic the end of the current service by writing the aic_eoicr (end of interrupt command register). the write of aic_eoicr is the exit point of the interrupt handling . 22.7.3.2 interrupt nesting the priority controller utilizes inte rrupt nesting in order for the high priori ty interrupt to be han- dled during the service of lower priority interrupt s. this requires the interrupt service routines of the lower interrupts to re-enable the interrupt at the processor level. when an interrupt of a higher priority happens during an already occurring interrupt service routine, the nirq line is re-asserted. if the interrupt is enabled at the core level, the current execution is interrupted and the new interrupt service routine should read the aic_ivr. at this time, the current interrupt number and its priority level are pushed into an embedded hardware stack, so that they are saved and restored when the higher priority interrupt servicing is fin- ished and the aic_eoicr is written. the aic is equipped with an 8-level wide hardware stack in order to support up to eight inter- rupt nestings pursuant to having eight priority levels. 22.7.3.3 interrupt vectoring the interrupt handler addresses corresponding to each interrupt source can be stored in the registers aic_svr1 to aic_svr31 (source ve ctor register 1 to 31). when the processor reads aic_ivr (interrupt vector register), the value written into aic_svr corresponding to the current interrupt is returned. this feature offers a way to branch in one single instruction to the handler corresponding to the current interrupt, as aic_ivr is mapped at the absolute address 0xffff f100 and thus accessible from the arm interrupt vector at address 0x0000 0018 through the following instruction:
133 6042e?atarm?14-dec-06 at91sam7a3 preliminary ldr pc,[pc,# -&f20] when the processor executes this instruction, it loads the read value in aic_ivr in its program counter, thus branching the execution on the correct interrupt handler. this feature is often not used when the application is based on an operating system (either real time or not). operating systems often have a single entry point for all the interrupts and the first task performed is to discern the source of the interrupt. however, it is strongly recommended to port th e operating system on at91 products by sup- porting the interrupt vectoring. this can be performed by defining all the aic_svr of the interrupt source to be handled by the operating system at the address of its interrupt handler. when doing so, the interrupt vectoring permits a critical interrupt to transfer the execution on a specific very fast handler and not onto the operating system?s general interrupt handler. this facilitates the support of hard real-time tasks (input/outputs of voice/audio buff ers and software peripheral handling) to be handled efficiently and independently of the application running under an operating system. 22.7.3.4 interrupt handlers this section gives an overview of the fast interrupt handling sequence when using the aic. it is assumed that the programmer understands the architecture of the arm processor, and especially the processor interrupt modes and the associated status bits. it is assumed that: 1. the advanced interrupt controller has been programmed, aic_svr registers are loaded with corresponding interrupt service routine addresses and interrupts are enabled. 2. the instruction at the arm interrupt exception vector address is required to work with the vectoring ldr pc, [pc, # -&f20] when nirq is asserted, if the bit ?i? of cpsr is 0, the sequence is as follows: 1. the cpsr is stored in spsr _irq, the curren t value of the program counter is loaded in the interrupt link register (r14_irq) and the program counter (r15) is loaded with 0x18. in the following cycle during fetch at address 0x1c, the arm core adjusts r14_irq, decrementing it by four. 2. the arm core enters interrupt mode, if it has not already done so. 3. when the instruction loaded at address 0x18 is executed, the program counter is loaded with the value read in aic_iv r. reading the aic_ivr has the following effects: ? sets the current interrupt to be the pending and enabled interrupt with the highest priority. the current level is the priority level of the current interrupt. ? de-asserts the nirq line on the processor. even if vectoring is not used, aic_ivr must be read in order to de-assert nirq. ? automatically clears the interrupt, if it has been programmed to be edge-triggered. ? pushes the current level and the current interrupt number on to the stack. ? returns the value written in the aic_svr corresponding to the current interrupt. 4. the previous step has the effect of branc hing to the corresponding interrupt service routine. this should start by saving the link register (r14_irq) and spsr_irq. the link register must be decremented by four when it is saved if it is to be restored
134 6042e?atarm?14-dec-06 at91sam7a3 preliminary directly into the program counter at the end of the interrupt. for example, the instruc- tion sub pc, lr, #4 may be used. 5. further interrupts can then be unmasked by clearing the ?i? bit in cpsr, allowing re- assertion of the nirq to be taken into account by the core. this can happen if an interrupt with a higher priority than the current interrupt occurs. 6. the interrupt handler can th en proceed as required, savi ng the registers that will be used and restoring them at the end. during this phase, an interrupt of higher priority than the current leve l will restart the sequence from step 1. note: if the interrupt is programmed to be level sens itive, the source of the interrupt must be cleared during this phase. 7. the ?i? bit in cpsr must be set in order to mask interrupts before exiting to ensure that the interrupt is completed in an orderly manner. 8. the end of interrupt command register (aic_eoicr) must be written in order to indicate to the aic that the current interrupt is finished. this causes the current level to be popped from the stack, restoring the previous current level if one exists on the stack. if another interrupt is pending, with lower or equal priority than the old current level but with higher priority than the new current level, the nirq line is re-asserted, but the interrupt sequence does not immediately start because the ?i? bit is set in the core. spsr_irq is restored. finally, the save d value of the link r egister is restored directly into the pc. this has the effect of returning from the interrupt to whatever was being executed before, and of loading th e cpsr with the stored spsr, masking or unmasking the interrupts depending on the state saved in spsr_irq. note: the ?i? bit in spsr is significant. if it is set, it indicates that the arm core was on the verge of masking an interrupt when the mask instruct ion was interrupted. h ence, when spsr is restored, the mask instruction is completed (interrupt is masked).
135 6042e?atarm?14-dec-06 at91sam7a3 preliminary 22.7.4 fast interrupt 22.7.4.1 fast interrupt source the interrupt source 0 is the only source which can raise a fast interrupt request to the proces- sor except if fast forcing is used. the interrupt source 0 is generally connected to a fiq pin of the product, either directly or through a pio controller. 22.7.4.2 fast interrupt control the fast interrupt logic of the aic has no priority controller. the mode of interrupt source 0 is programmed with the aic_smr0 and the field prior of this register is not used even if it reads what has been written. the field sr ctype of aic_smr0 enables programming the fast interrupt source to be positive-edge triggered or negative-edge triggered or high-level sen- sitive or low-level sensitive writing 0x1 in the aic_iecr (interrupt enable command register) a nd aic_idcr (interrupt disable command register) respec tively enables and disables the fast interrupt. the bit 0 of aic_imr (interrupt mask register) indicates whet her the fast interrupt is enabled or disabled. 22.7.4.3 fast interrupt vectoring the fast interrupt handler address can be stored in aic_svr0 (source vector register 0). the value written into this register is returned when the processor reads aic_fvr (fast vec- tor register). this offers a way to branch in one single instruction to the interrupt handler, as aic_fvr is mapped at the absolute address 0x ffff f104 and thus accessible from the arm fast interrupt vector at address 0x0000 001c through the following instruction: ldr pc,[pc,# -&f20] when the processor executes th is instruction it loads the va lue read in aic_fvr in its pro- gram counter, thus branching the execution on the fast interrupt handler. it also automatically performs the clear of the fast interrupt source if it is programmed in edge-triggered mode. 22.7.4.4 fast interrupt handlers this section gives an overview of the fast interrupt handling sequence when using the aic. it is assumed that the programmer understands the architecture of the arm processor, and especially the processor interrupt modes and associated status bits. assuming that: 1. the advanced interrupt controller has been programmed, aic_svr0 is loaded with the fast interrupt service routine address, and the interrupt source 0 is enabled. 2. the instruction at address 0x1c (fiq exception vector address) is required to vector the fast interrupt: ldr pc, [pc, # -&f20] 3. the user does not need nested fast interrupts. when nfiq is asserted, if the bit ?f? of cpsr is 0, the sequence is: 1. the cpsr is stored in spsr _fiq, the current va lue of the program counter is loaded in the fiq link register (r14_fiq) and the program counter (r15) is loaded with 0x1c. in the following cycle, during fetch at address 0x20, the arm core adjusts r14_fiq, decrementing it by four. 2. the arm core enters fiq mode. 3. when the instruction loaded at address 0x1c is executed, the program counter is loaded with the value read in aic_fvr. reading the aic_fvr has effect of automat-
136 6042e?atarm?14-dec-06 at91sam7a3 preliminary ically clearing the fast interrupt, if it has been programmed to be edge triggered. in this case only, it de-asserts the nfiq line on the processor. 4. the previous step enables branching to the corresponding interrupt service routine. it is not necessary to save the link register r14_fiq and spsr_fiq if nested fast inter- rupts are not needed. 5. the interrupt handler can then proceed as required. it is not necessary to save regis- ters r8 to r13 because fiq mode has its own dedicated registers and the user r8 to r13 are banked. the other registers, r0 to r7, must be saved before being used, and restored at the end (before the next step). note that if the fast interrupt is pro- grammed to be level sensitive, the source of the interrupt must be cleared during this phase in order to de-assert the interrupt source 0. 6. finally, the link register r14_fiq is restored into the pc after decrementing it by four (with instruction sub pc, lr, #4 for example). this has the effect of returning from the interrupt to whatever was being executed before, loading the cpsr with the spsr and masking or unmasking the fast in terrupt depending on the state saved in the spsr. note: the ?f? bit in spsr is signific ant. if it is set, it indicates t hat the arm core was just about to mask fiq interrupts when the mask instructio n was interrupted. hence when the spsr is restored, the interrupted instructi on is completed (fiq is masked). another way to handle the fast interrupt is to map the interrupt service routine at the address of the arm vector 0x1c. this method does not use the vectoring, so that reading aic_fvr must be performed at the very beginning of the handler operation. however, this method saves the execution of a branch instruction. 22.7.4.5 fast forcing the fast forcing feature of the advanced interrupt controller provides redirection of any nor- mal interrupt source on the fast interrupt controller. fast forcing is enabled or disabled by writ ing to the fast forcing enable register (aic_ffer) and the fast forcing disable regi ster (aic_ffdr). writing to these registers results in an update of the fast forcing status register (aic_ffsr) that controls the feature for each internal or external interrupt source. when fast forcing is disabled, the interrupt sources are handled as described in the previous pages. when fast forcing is enabled, the edge/level programming and, in certain cases, edge detec- tion of the interrupt source is st ill active but the source cannot tr igger a normal in terrupt to the processor and is not seen by the priority handler. if the interrupt source is programmed in level-sensitive mode and an active level is sampled, fast forcing results in the assertion of the nfiq line to the core. if the interrupt source is programmed in edge-triggered mode and an active edge is detected, fast forcing results in the assertion of the nfiq line to the core. the fast forcing feature does not affect the source 0 pending bit in the interrupt pending register (aic_ipr). the fiq vector register (aic_fvr) reads the contents of the source vector register 0 (aic_svr0), whatever the source of the fast interrupt may be. the read of the fvr does not clear the source 0 when the fast forcing feature is used and the interrupt source should be cleared by writin g to the inte rrupt clear command register (aic_iccr).
137 6042e?atarm?14-dec-06 at91sam7a3 preliminary all enabled and pending interrupt sources that have the fast forcing feature enabled and that are programmed in edge-triggered mode must be cleared by writing to the interrupt clear command register. in doing so, they are cleared independently and thus lost interrupts are prevented. the read of aic_ivr does not clear the source that has the fast forcing feature enabled. the source 0, reserved to the fast interrupt, continues operating normally and becomes one of the fast interrupt sources. figure 22-10. fast forcing source 0 _ fiq input stage automatic clear input stage automatic clear source n aic_ipr aic_imr aic_ffsr aic_ipr aic_imr priority manager nfiq nirq read ivr if source n is the current interrupt and if fast forcing is disabled on source n. read fvr if fast forcing is disabled on sources 1 to 31.
138 6042e?atarm?14-dec-06 at91sam7a3 preliminary 22.7.5 protect mode the protect mode permits reading the interrupt vector register without performing the associ- ated automatic operations. this is necessary when working with a debug system. when a debugger, working either with a debug monitor or the arm processor's ice, stops the applica- tions and updates the opened windows, it might re ad the aic user interface and thus the ivr. this has undesirable consequences: if an enabled interrupt with a higher priority than the current one is pending, it is stacked. if there is no enabled pending interrupt, the spurious vector is returned. in either case, an end of interrupt command is necessary to acknowledge and to restore the context of the aic. this operation is generally not performed by the debug system as the debug system would become strongly intrusive and cause the application to enter an undes- ired state. this is avoided by using the protect mode. writing dbgm in aic_dcr (debug control regis- ter) at 0x1 enables the protect mode. when the protect mode is enabled, the aic performs interrupt stacking only when a write access is performed on the aic_ivr. therefore, the interrupt service routines must write (arbitrary data) to the aic_ivr just after reading it. the new context of the aic, including the value of the interrupt status register (aic_isr), is updated with the current interrupt only when aic_ivr is written. an aic_ivr read on its own (e.g., by a debugger), modifies neither the aic context nor the aic_isr. extra aic_ivr reads perform the same operations. however, it is recommended to not stop the processor between the read and the write of aic_ivr of the interrupt service rou- tine to make sure the debugger does not modify the aic context. to summarize, in normal operating mode, the read of aic_ivr performs the following opera- tions within the aic: 1. calculates active interrupt (higher than current or spurious). 2. determines and returns the vector of the active interrupt. 3. memorizes the interrupt. 4. pushes the current priority level onto the internal stack. 5. acknowledges the interrupt. however, while the protect mode is activat ed, only operations 1 to 3 are performed when aic_ivr is read. operations 4 and 5 are only performed by the aic when aic_ivr is written. software that has been written and debugged using the protect mode runs correctly in normal mode without modification. however, in normal mode the aic_ivr write has no effect and can be removed to optimize the code. 22.7.6 spurious interrupt the advanced interrupt controller features prot ection against spurious interrupts. a spurious interrupt is defined as being the assertion of an interrupt source long enough for the aic to assert the nirq, but no longer present when aic_ivr is read. this is most prone to occur when: an external interrupt source is programmed in level-sensitive mode and an active level occurs for only a short time.
139 6042e?atarm?14-dec-06 at91sam7a3 preliminary an internal interrupt source is programmed in level sensitive and the output signal of the corresponding embedded peripheral is activated for a short time. (as in the case for the watchdog.) an interrupt occurs just a few cycles before the software begins to mask it, thus resulting in a pulse on the interrupt source. the aic detects a spurious interrupt at the time the aic_ivr is read while no enabled interrupt source is pending. when this happens, the aic returns the value stored by the programmer in aic_spu (spurious vector register). the programmer must store the address of a spurious interrupt handler in aic_spu as part of the application, to enable an as fast as possible return to the normal execution flow. this handler writes in aic_eoicr and performs a return from interrupt. 22.7.7 general interrupt mask the aic features a general interrupt mask bit to prevent interrupts from reaching the proces- sor. both the nirq and the nfiq lines are driven to their inactive state if the bit gmsk in aic_dcr (debug control register) is set. however, this mask does not prevent waking up the processor if it has entered idle mo de. this function facilitates synchronizing the processor on a next event and, as soon as the event occurs, performs subsequent operations without having to handle an interrupt. it is strongly recommended to use this mask with caution.
140 6042e?atarm?14-dec-06 at91sam7a3 preliminary 22.8 advanced interrupt controll er (aic) user interface 22.8.1 base address the aic is mapped at the address 0xffff f000 . it has a total 4-kbyte addressing space. this permits the vectoring feature, as the pc-relative load/store instructions of the arm processor support only a 4-kbyte offset. 22.8.2 register mapping notes: 1. the reset value of this register depends on the level of the external interrupt source. all other sources are cleared a t reset, thus not pending. 2. pid2...pid31 bit fields refer to the identifiers as defined in the peripheral identifiers se ction of the product datasheet. table 22-2. register mapping offset register name access reset value 0000 source mode register 0 aic_smr0 read/write 0x0 0x04 source mode register 1 aic_smr1 read/write 0x0 --- --- --- --- --- 0x7c source mode register 31 aic_smr31 read/write 0x0 0x80 source vector register 0 aic_svr0 read/write 0x0 0x84 source vector register 1 aic_svr1 read/write 0x0 --- --- --- --- --- 0xfc source vector register 31 aic_svr31 read/write 0x0 0x100 interrupt vector register aic_ivr read-only 0x0 0x104 fiq interrupt vector register aic_fvr read-only 0x0 0x108 interrupt status register aic_isr read-only 0x0 0x10c interrupt pending register (2) aic_ipr read-only 0x0 (1) 0x110 interrupt mask register (2) aic_imr read-only 0x0 0x114 core interrupt status register aic_cisr read-only 0x0 0x118 reserved --- --- --- 0x11c reserved --- --- --- 0x120 interrupt enable command register (2) aic_iecr write-only --- 0x124 interrupt disable command register (2) aic_idcr write-only --- 0x128 interrupt clear command register (2) aic_iccr write-only --- 0x12c interrupt set command register (2) aic_iscr write-only --- 0x130 end of interrupt command register aic_eoicr write-only --- 0x134 spurious interrupt vector register aic_spu read/write 0x0 0x138 debug control register aic_dcr read/write 0x0 0x13c reserved --- --- --- 0x140 fast forcing enable register (2) aic_ffer write-only --- 0x144 fast forcing disable register (2) aic_ffdr write-only --- 0x148 fast forcing status register (2) aic_ffsr read-only 0x0
141 6042e?atarm?14-dec-06 at91sam7a3 preliminary 22.8.3 aic source mode register register name: aic_smr0..aic_smr31 access type: read/write reset value: 0x0 prior: priority level programs the priority level for all sources except fiq source (source 0). the priority level can be between 0 (lowest) and 7 (highest). the priority level is not used for the fi q in the related smr register aic_smrx. srctype: interrupt source type the active level or edge is not programmable for the internal interrupt sources. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ???????? 76543210 ? srctype ? ? prior srctype internal interrupt sources external interrupt sources 0 0 high level sensitive low level sensitive 0 1 positive edge triggered negative edge triggered 1 0 high level sensitive high level sensitive 1 1 positive edge triggered positive edge triggered
142 6042e?atarm?14-dec-06 at91sam7a3 preliminary 22.8.4 aic source vector register register name: aic_svr0..aic_svr31 access type: read/write reset value: 0x0 vector: source vector the user may store in these registers the addresses of the corresponding handler for each interrupt source. 22.8.5 aic interrupt vector register register name: aic_ivr access type: read-only reset value: 0x0 irqv: interrupt vector register the interrupt vector register contains the vector programmed by the user in the source vector register corresponding to the current interrupt. the source vector register is indexed using the current interrupt number when the interrupt vector register is read. when there is no current interrupt, the interrupt vector register reads the value stored in aic_spu. 31 30 29 28 27 26 25 24 vector 23 22 21 20 19 18 17 16 vector 15 14 13 12 11 10 9 8 vector 76543210 vector 31 30 29 28 27 26 25 24 irqv 23 22 21 20 19 18 17 16 irqv 15 14 13 12 11 10 9 8 irqv 76543210 irqv
143 6042e?atarm?14-dec-06 at91sam7a3 preliminary 22.8.6 aic fiq vector register register name: aic_fvr access type: read-only reset value: 0 x0 fiqv: fiq vector register the fiq vector register contains the vector programmed by the user in the source vector register 0. when there is no fast interrupt, the fiq vector register reads the value stored in aic_spu. 22.8.7 aic interrupt status register register name: aic_isr access type: read-only reset value: 0x0 irqid: current interrupt identifier the interrupt status register returns the current interrupt source number. 31 30 29 28 27 26 25 24 fiqv 23 22 21 20 19 18 17 16 fiqv 15 14 13 12 11 10 9 8 fiqv 76543210 fiqv 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ???????? 76543210 ??? irqid
144 6042e?atarm?14-dec-06 at91sam7a3 preliminary 22.8.8 aic interrupt pending register register name: aic_ipr access type: read-only reset value: 0x0 fiq, sys, pid2-pid31: interrupt pending 0 = corresponding interrupt is not pending. 1 = corresponding interrupt is pending. 22.8.9 aic interrupt mask register register name: aic_imr access type: read-only reset value: 0x0 fiq, sys, pid2-pid31: interrupt mask 0 = corresponding interrupt is disabled. 1 = corresponding interrupt is enabled. 31 30 29 28 27 26 25 24 pid31 pid30 pid29 pid28 pid27 pid26 pid25 pid24 23 22 21 20 19 18 17 16 pid23 pid22 pid21 pid20 pid19 pid18 pid17 pid16 15 14 13 12 11 10 9 8 pid15 pid14 pid13 pid12 pid11 pid10 pid9 pid8 76543210 pid7 pid6 pid5 pid4 pid3 pid2 sys fiq 31 30 29 28 27 26 25 24 pid31 pid30 pid29 pid28 pid27 pid26 pid25 pid24 23 22 21 20 19 18 17 16 pid23 pid22 pid21 pid20 pid19 pid18 pid17 pid16 15 14 13 12 11 10 9 8 pid15 pid14 pid13 pid12 pid11 pid10 pid9 pid8 76543210 pid7 pid6 pid5 pid4 pid3 pid2 sys fiq
145 6042e?atarm?14-dec-06 at91sam7a3 preliminary 22.8.10 aic core interrupt status register register name: aic_cisr access type: read-only reset value: 0x0 nfiq: nfiq status 0 = nfiq line is deactivated. 1 = nfiq line is active. nirq: nirq status 0 = nirq line is deactivated. 1 = nirq line is active. 22.8.11 aic interrupt enable command register register name: aic_iecr access type: write-only fiq, sys, pid2-pid3: interrupt enable 0 = no effect. 1 = enables corresponding interrupt. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ???????? 76543210 ??????nirqnifq 31 30 29 28 27 26 25 24 pid31 pid30 pid29 pid28 pid27 pid26 pid25 pid24 23 22 21 20 19 18 17 16 pid23 pid22 pid21 pid20 pid19 pid18 pid17 pid16 15 14 13 12 11 10 9 8 pid15 pid14 pid13 pid12 pid11 pid10 pid9 pid8 76543210 pid7 pid6 pid5 pid4 pid3 pid2 sys fiq
146 6042e?atarm?14-dec-06 at91sam7a3 preliminary 22.8.12 aic interrupt disable command register register name: aic_idcr access type: write-only fiq, sys, pid2-pid31: interrupt disable 0 = no effect. 1 = disables corresponding interrupt. 22.8.13 aic interrupt clear command register register name: aic_iccr access type: write-only fiq, sys, pid2-pid31: interrupt clear 0 = no effect. 1 = clears corresponding interrupt. 31 30 29 28 27 26 25 24 pid31 pid30 pid29 pid28 pid27 pid26 pid25 pid24 23 22 21 20 19 18 17 16 pid23 pid22 pid21 pid20 pid19 pid18 pid17 pid16 15 14 13 12 11 10 9 8 pid15 pid14 pid13 pid12 pid11 pid10 pid9 pid8 76543210 pid7 pid6 pid5 pid4 pid3 pid2 sys fiq 31 30 29 28 27 26 25 24 pid31 pid30 pid29 pid28 pid27 pid26 pid25 pid24 23 22 21 20 19 18 17 16 pid23 pid22 pid21 pid20 pid19 pid18 pid17 pid16 15 14 13 12 11 10 9 8 pid15 pid14 pid13 pid12 pid11 pid10 pid9 pid8 76543210 pid7 pid6 pid5 pid4 pid3 pid2 sys fiq
147 6042e?atarm?14-dec-06 at91sam7a3 preliminary 22.8.14 aic interrupt set command register register name: aic_iscr access type: write-only fiq, sys, pid2-pid31: interrupt set 0 = no effect. 1 = sets corresponding interrupt. 22.8.15 aic end of interrupt command register register name: aic_eoicr access type: write-only the end of interrupt command register is used by the interrupt routine to indicate that the interrupt treatment is complete. any value can be written because it is only necessary to make a write to this register location to signal the end of interrupt treatment. 31 30 29 28 27 26 25 24 pid31 pid30 pid29 pid28 pid27 pid26 pid25 pid24 23 22 21 20 19 18 17 16 pid23 pid22 pid21 pid20 pid19 pid18 pid17 pid16 15 14 13 12 11 10 9 8 pid15 pid14 pid13 pid12 pid11 pid10 pid9 pid8 76543210 pid7 pid6 pid5 pid4 pid3 pid2 sys fiq 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ???????? 76543210 ????????
148 6042e?atarm?14-dec-06 at91sam7a3 preliminary 22.8.16 aic spurious interrupt vector register register name: aic_spu access type: read/write reset value: 0x0 siqv: spurious interrupt vector register the user may store the address of a spurious interrupt handler in this register. the written value is returned in aic_ivr in case of a spurious interrupt and in aic_fvr in case of a spurious fast interrupt. 22.8.17 aic debug control register register name: aic_debug access type: read/write reset value: 0x0 prot: protection mode 0 = the protection mode is disabled. 1 = the protection mode is enabled. gmsk: general mask 0 = the nirq and nfiq lines are normally controlled by the aic. 1 = the nirq and nfiq lines are tied to their inactive state. 31 30 29 28 27 26 25 24 siqv 23 22 21 20 19 18 17 16 siqv 15 14 13 12 11 10 9 8 siqv 76543210 siqv 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ???????? 76543210 ??????gmskprot
149 6042e?atarm?14-dec-06 at91sam7a3 preliminary 22.8.18 aic fast forcing enable register register name: aic_ffer access type: write-only sys, pid2-pid31: fast forcing enable 0 = no effect. 1 = enables the fast forcing feature on the corresponding interrupt. 22.8.19 aic fast forcing disable register register name: aic_ffdr access type: write-only sys, pid2-pid31: fast forcing disable 0 = no effect. 1 = disables the fast forcing feature on the corresponding interrupt. 31 30 29 28 27 26 25 24 pid31 pid30 pid29 pid28 pid27 pid26 pid25 pid24 23 22 21 20 19 18 17 16 pid23 pid22 pid21 pid20 pid19 pid18 pid17 pid16 15 14 13 12 11 10 9 8 pid15 pid14 pid13 pid12 pid11 pid10 pid9 pid8 76543210 pid7 pid6 pid5 pid4 pid3 pid2 sys ? 31 30 29 28 27 26 25 24 pid31 pid30 pid29 pid28 pid27 pid26 pid25 pid24 23 22 21 20 19 18 17 16 pid23 pid22 pid21 pid20 pid19 pid18 pid17 pid16 15 14 13 12 11 10 9 8 pid15 pid14 pid13 pid12 pid11 pid10 pid9 pid8 76543210 pid7 pid6 pid5 pid4 pid3 pid2 sys ?
150 6042e?atarm?14-dec-06 at91sam7a3 preliminary 22.8.20 aic fast forcing status register register name: aic_ffsr access type: read-only sys, pid2-pid31: fast forcing status 0 = the fast forcing feature is disabled on the corresponding interrupt. 1 = the fast forcing feature is enabled on the corresponding interrupt. 31 30 29 28 27 26 25 24 pid31 pid30 pid29 pid28 pid27 pid26 pid25 pid24 23 22 21 20 19 18 17 16 pid23 pid22 pid21 pid20 pid19 pid18 pid17 pid16 15 14 13 12 11 10 9 8 pid15 pid14 pid13 pid12 pid11 pid10 pid9 pid8 76543210 pid7 pid6 pid5 pid4 pid3 pid2 sys ?
151 6042e?atarm?14-dec-06 at91sam7a3 preliminary 23. clock generator 23.1 description the clock generator is made up of 1 pll, a main oscillato r, as well as an rc oscillator . it provides the following clocks: slck, the slow clock, which is the only permanent clock within the system mainck is the output of the main oscillator pllck is the output of the divider and pll block the clock generator user interface is embedded within the power management controller one and is described in section 24.9 . however, the clock generator registers are named ckgr_. 23.2 slow clock rc oscillator the user has to take into accoun t the possible drifts of the rc oscillator. more details are given in the section ?dc characteristics? of the product datasheet. 23.3 main oscillator figure 23-1 shows the main oscillator block diagram. figure 23-1. main oscillator block diagram 23.3.1 main oscillator connections the clock generator integr ates a main oscillator that is desi gned for a 3 to 20 mhz fundamental crystal. the typical crystal connection is illustrated in figure 23-2 . the 1 k ? resistor is only required for crystals with frequencies lower than 8 mhz. for further details on the electrical char- acteristics of the main oscillato r, see the sectio n ?dc characteristics? of the product datasheet. xin xout moscen main oscillator counter oscount moscs mainck main clock main clock frequency counter mainf mainrdy slck slow clock main oscillator
152 6042e?atarm?14-dec-06 at91sam7a3 preliminary figure 23-2. typical crystal connection 23.3.2 main oscillator startup time the startup time of the main oscillator is given in the dc characteristics section of the product datasheet. the startup time depends on the crystal frequency and decreases when the fre- quency rises. 23.3.3 main oscillator control to minimize the power required to start up the sy stem, the main oscillator is disabled after reset and slow clock is selected. the software enable s or disables the main oscillator so as to reduce powe r consumption by clearing the moscen bit in the ma in oscillator regi ster (ckgr_mor). when disabling the main oscillator by clearin g the moscen bit in ckgr_mor, the moscs bit in pmc_sr is automatica lly cleared, indicating the main clock is off. when enabling the main oscillator, the user must initiate the ma in oscillator coun ter with a value corresponding to the startup time of the oscillat or. this startup time depends on the crystal fre- quency connected to the main oscillator. when the moscen bit and the oscount are written in ckgr_mor to enable the main oscil- lator, the moscs bit in pmc_sr (status register) is cleared and the counter starts counting down on the slow clock divided by 8 from the oscount value. since the oscount value is coded with 8 bits, the maximum startup time is about 62 ms. when the counter reaches 0, the moscs bit is set, indicating that the main clock is valid. set- ting the moscs bit in pmc_imr can trigger an interrupt to the processor. 23.3.4 main clock frequency counter the main oscillator feat ures a main clock frequen cy counter that provides the quartz frequency connected to the main oscillator. generally, this value is know n by the system designer; how- ever, it is useful for the boot program to c onfigure the device with the correct clock speed, independently of the application. the main clock frequency counter starts incrementing at the main clock speed after the next ris- ing edge of the slow clock as soon as the main oscillator is stab le, i.e., as soon as the moscs bit is set. then, at th e 16th falling edge of slow clock, the mainrdy bit in ckgr_mcfr (main clock frequency register) is set and the counter stops counting. its value can be read in the mainf field of ckgr_mcfr and gives the number of main clock cycles during 16 periods of slow clock, so that the frequency of the crystal connected on the main oscillator can be determined. 1k xin xout gnd c l2 c l1
153 6042e?atarm?14-dec-06 at91sam7a3 preliminary 23.3.5 main oscillator bypass the user can input a clock on the device instead of connecting a crystal. in this case, the user has to provide the external clock signal on the xi n pin. the input characteristics of the xin pin under these conditions are given in the product el ectrical characteristics section. the program- mer has to be sure to set the oscbypass bit to 1 and the moscen bit to 0 in the main osc register (ckgr_mor) for the external clock to operate properly. 23.4 divider and pll block the pll embeds an input divider to increase the accuracy of the resulting clock signals. how- ever, the user must respect the pll minimum input frequency when programming the divider. figure 23-3 shows the block diagram of the divider and pll block. figure 23-3. divider and pll block diagram 23.4.1 pll filter the pll requires connection to an external sec ond-order filter through the pllrc pin. figure 23-4 shows a schematic of these filters. figure 23-4. pll capacitors and resistors values of r, c1 and c2 to be connected to the pllrc pin must be calculated as a function of the pll input frequency, the pll output frequency and the phase margin. a trade-off has to be found between output signal overshoot and startup time. divider pllrc div pll mul pllcount lock out slck mainck pllck pll counter gnd c1 c2 pll pllrc r
154 6042e?atarm?14-dec-06 at91sam7a3 preliminary 23.4.2 divider and phase lock loop programming the divider can be set between 1 and 255 in steps of 1. when a divider field (div) is set to 0, the output of the corresponding divider and the pll out put is a continuous signal at level 0. on reset, each div field is set to 0, thus the corresponding pll input clock is set to 0. the pll allows multiplication of the divider?s out puts. the pll clock signal has a frequency that depends on the respective source signal frequency and on the parameters div and mul. the factor applied to the source signal frequency is (mul + 1)/div. when mul is written to 0, the corresponding pll is disabled and its power consumption is saved. re-enabling the pll can be performed by writing a value higher than 0 in the mul field. whenever the pll is re-enabled or one of its parameters is changed, the lock bit in pmc_sr is automatically cleared. the va lues written in the pllcount fi eld in ckgr_pllr are loaded in the pll counter. the pll counter then decrements at the speed of the slow clock until it reaches 0. at this time, the lock bit is set in pmc_sr and can trigger an interrupt to the pro- cessor. the user has to load the number of slow clock cycles required to cover the pll transient time into the pllcount field. the transient time depends on the pll filter. the initial state of the pll and its target frequency can be calculated using a specific tool provided by atmel.
155 6042e?atarm?14-dec-06 at91sam7a3 preliminary 24. power management controller (pmc) 24.1 description the power management controller (pmc) optimizes power consumption by controlling all sys- tem and user peripheral clocks. the pmc enables/disables the clock inputs to many of the peripherals and the arm processor. the power management controller provides the following clocks: mck, the master clock, programmable from a few hundred hz to the maximum operating frequency of the device. it is available to the modules running permanently, such as the aic and the memory controller. processor clock (pck), switched off wh en entering processor in idle mode. peripheral clocks, typically mck, provided to the embedded peripherals (usart, ssc, spi, twi, tc, mci, etc.) and independently controllable. in order to reduce the number of clock names in a product, the peripheral clocks are named mck in the product datasheet. udp clock (udpck), required by usb device port operations. programmable clock outputs can be selected from the clocks provided by the clock generator and driven on the pckx pins. 24.2 master clock controller the master clock controller provides selection and division of the master clock (mck). mck is the clock provided to all the peripherals and the memory controller. the master clock is selected from one of the clocks provided by the clock generator. selecting the slow clock provides a slow clock signal to the whole device. selecting the main clock saves power consumption of the pll. the master clock controller is made up of a clock selector and a prescaler. the master clock selection is made by writing the css field (clock source selection) in pmc_mckr (master clock register). the prescaler supports the division by a power of 2 of the selected clock between 1 and 64. the pres field in pmc_mckr programs the prescaler. each time pmc_mckr is written to define a ne w master clock, the mckr dy bit is cleared in pmc_sr. it reads 0 until the master clock is es tablished. then, the mckrdy bit is set and can trigger an interrupt to the processor. this feature is useful when switching from a high-speed clock to a lower one to inform the software when the change is actually done. figure 24-1. master clock controller slck master clock prescaler mck pres css mainck pllck to the processor clock controller (pck) pmc_mckr pmc_mckr
156 6042e?atarm?14-dec-06 at91sam7a3 preliminary 24.3 processor clock controller the pmc features a processor clock controller (pck) that implements the processor idle mode. the processor clock can be enabled and disabled by writing the system clock enable (pmc_scer) and system clock di sable registers (pmc _scdr). the status of this clock (at least for debug purpose) can be read in the system clock status register (pmc_scsr). the processor clock pck is enabled after a reset and is automatically re-enabled by any enabled interrupt. the processor idle mode is ac hieved by disabling the processor clock, which is automatically re-enabled by any enabled fast or normal interrupt, or by the reset of the product. when the processor clock is disabled, the current instruction is finished before the clock is stopped, but this does not prevent data transfers from other masters of the system bus. 24.4 usb clock controller the usb source clock is the pll output. if using the usb, the user must program the pll to generate a 48 mhz, a 96 mhz or a 192 mhz signal with an accuracy of 0.25% depending on the usbdiv bit in ckgr_pllr. when the pll output is stable, i.e., the lock bit is set: the usb device clock can be enabled by setting the udp bit in pmc_scer. to save power on this peripheral when it is not used, the user can set the udp bit in pmc_scdr. the udp bit in pmc_scsr gives the activity of this clock. the usb device port require both the 48 mhz signal and the master clock. the master clock may be controlled via the peripheral clock controller. figure 24-2. usb clock controller 24.5 peripheral clock controller the power management controller controls the clocks of each embedded peripheral by the way of the peripheral clock controller. the user can individually enable and disable the master clock on the peripherals by writing into the peripheral clock enable (pmc_pcer) and periph- eral clock disable (pmc_pcdr) registers. the status of the peripheral clock activity can be read in the peripheral clock status register (pmc_pcsr). when a peripheral clock is disabled, the clock is immediately stopped. the peripheral clocks are automatically disabled after a reset. in order to stop a peri pheral, it is recommended that the syst em software wait until the peripheral has executed its last programmed operation before disabling the clock. this is to avoid data cor- ruption or erroneous behavior of the system. usb source clock udp clock (udpck) udp usbdiv divider /1,/2,/4
157 6042e?atarm?14-dec-06 at91sam7a3 preliminary the bit number within the peripheral clock control registers (pmc_pcer, pmc_pcdr, and pmc_pcsr) is the peripheral identifier defined at the product level. generally, the bit number corresponds to the interrupt source number assigned to the peripheral. 24.6 programmable clock output controller the pmc controls 4 signals to be output on ex ternal pins pckx. ea ch signal can be indepen- dently programmed via the pmc_pckx registers. pckx can be independently selected between the slow clock, the pll output and the main clock by writing the css field in pmc_pckx. each output signal can also be divided by a power of 2 between 1 and 64 by writing the pres (prescaler) field in pmc_pckx. each output signal can be enabled and disabled by writing 1 in the corresponding bit, pckx of pmc_scer and pmc_scdr, respectively. status of the active programmable output clocks are given in the pckx bits of pmc_scsr (system clock status register). moreover, like the pck, a status bitin pmc_sr indicates that the programmable clock is actu- ally what has been programmed in the programmable clock registers. as the programmable clock controller does not manage with glitch prevention when switching clocks, it is strongly recommended to disable the programmable clock before any configuration change and to re-enable it after the change is actually performed. 24.7 programming sequence 1. enabling the main oscillator: the main oscillator is enabled by setting the moscen field in the ckgr_mor register. in some cases it may be advantageous to define a start-up time. this can be achieved by writ- ing a value in the oscount field in the ckgr_mor register. once this register has been correctly configured, the user must wait for moscs field in the pmc_sr register to be set. this can be done either by polling th e status register or by wait- ing the interrupt line to be raised if the associated interrupt to moscs has been enabled in the pmc_ier register. code example: write_register(ckgr_mor,0x00000701) start up time = 8 * oscount / slck = 56 slow clock cycles. so, the main oscillator will be enabled (moscs bit set) after 56 slow clock cycles. 2. checking the main oscilla tor frequency (optional): in some situations the user may need an accurate measure of the main oscillator frequency. this measure can be accomplished via the ckgr_mcfr register. once the mainrdy field is set in ckgr_mcfr register, the user may read the mainf field in ckgr_mcfr register. this provides the numb er of main clock cycles within sixteen slow clock cycles. 3. setting pll and divider:
158 6042e?atarm?14-dec-06 at91sam7a3 preliminary all parameters needed to configure pll and the divider are located in the ckgr_pllr register. the div field is used to control divider itself. a value between 0 and 255 can be programmed. divider output is divider input divided by div pa rameter. by default div parameter is set to 0 which means that divider is turned off. the out field is used to select the pll b output frequency range. the mul field is the pll multiplier factor . this parameter can be programmed between 0 and 2047. if mul is set to 0, pll will be turned off, otherwise the p ll output frequency is pll input frequency mult iplied by (mul + 1). the pllcount field specifies the number of slow clock cycles before lock bit is set in the pmc_sr register after ckgr_pllr register has been written. once the pmc_pll register has been written, the user must wait for the lock bit to be set in the pmc_sr register. this can be done either by polling the status register or by waiting the interrupt line to be raised if the associated interrupt to lock has been enabled in the pmc_ier register. all parameters in ckgr_pllr can be programmed in a single write operation. if at some stage one of the following parameters, mul, div is modified, lock bit will go low to indicate that pll is not ready yet. when pll is locked, lock will be set again. the user is constrained to wait for lock bi t to be set before using the pll output clock. the usbdiv field is used to control the additional divider by 1, 2 or 4, which generates the usb clock(s). code example: write_register(ckgr_pllr,0x00040805) if pll and divider are enabled, the pll input cloc k is the main clock. pll output clock is pll input clock multiplied by 5. once ckgr_pllr has been written, lock bit will be set after eight slow clock cycles. 4. selection of master clock and processor clock the master clock and the processor clock are configurable via the pmc_mckr register. the css field is used to select the master clock divider source. by default, the selected clock source is slow clock. the pres field is used to control the master clo ck prescaler. the user can choose between different values (1, 2, 4, 8, 16, 32, 64). mast er clock output is prescaler input divided by pres parameter. by default, pres parameter is set to 1 which means that master clock is equal to slow clock. once the pmc_mckr register has been written, the user must wait for the mckrdy bit to be set in the pmc_sr register. this can be done either by polling the status register or by waiting for the interrupt line to be raised if the associated interrupt to mckrdy has been enabled in the pmc_ier register. the pmc_mckr register must not be programmed in a single write operation. the preferred programming sequence for the pmc_mckr register is as follows:
159 6042e?atarm?14-dec-06 at91sam7a3 preliminary if a new value for css field corresponds to pll clock, ? program the pres field in the pmc_mckr register. ? wait for the mckrdy bit to be set in the pmc_sr register. ? program the css field in the pmc_mckr register. ? wait for the mckrdy bit to be set in the pmc_sr register. if a new value for css field corresponds to main clock or slow clock, ? program the css field in the pmc_mckr register. ? wait for the mckrdy bit to be set in the pmc_sr register. ? program the pres field in the pmc_mckr register. ? wait for the mckrdy bit to be set in the pmc_sr register. if at some stage one of the following parameters, css or pres, is modified, the mckrdy bit will go low to indicate that the master clock and the processor clock are not ready yet. the user must wait for mckrdy bit to be set again before using the master and processor clocks. note: if pllx clock was selected as the master clock and the user decides to modify it by writing in ckgr_pllr, the mckrdy flag will go low while pll is unlocked. once pll is locked again, lock goes high and mckrdy is set. while pll is unlocked, the master clock selection is automatically changed to main clock. for fur- ther information, see section 24.8.2 . ?clock switching waveforms? on page 161 . code example: write_register(pmc_mckr,0x00000001) wait (mckrdy=1) write_register(pmc_mckr,0x00000011) wait (mckrdy=1) the master clock is main clock divided by 16. the processor clock is the master clock. 5. selection of programmable clocks programmable clocks are controlled vi a registers; pmc_scer, pmc_scdr and pmc_scsr. programmable clocks can be enabled and/or disabled via the pmc_scer and pmc_scdr registers. depending on the system used, 4 programmable clocks can be enabled or dis- abled. the pmc_scsr provides a clear indication as to which programmable clock is enabled. by default all programmable clocks are disabled. pmc_pckx registers are used to configure programmable clocks. the css field is used to select the programma ble clock divider source. four clock options are available: main clock, slow clock, pllck. by default, the clock source selected is slow clock. the pres field is used to control the programmable clock prescaler. it is possible to choose between different values (1, 2, 4, 8, 16, 32, 64). programmable clock output is prescaler input divided by pres parameter. by default, the pres parameter is set to 1 which means that master clock is equal to slow clock.
160 6042e?atarm?14-dec-06 at91sam7a3 preliminary once the pmc_pckx register has been programmed, the corresponding programmable clock must be enabled and the user is constrained to wait for the pckrdyx bit to be set in the pmc_sr register. this can be done either by polling the stat us register or by waiting the interrupt line to be raised if the associated interrupt to pckrdyx has been enabled in the pmc_ier register. all parameters in pmc_pckx can be programmed in a single write operation. if the css and pres parameters are to be modified, the corresponding programmable clock must be disabled first. the parameters can then be modified. once this has been done, the user must re-enable the programmable clock and wait for the pckrdyx bit to be set. code example: write_register(pmc_pck0,0x00000015) programmable clock 0 is main clock divided by 32. 6. enabling peripheral clocks once all of the previous steps have been completed, the peripheral clocks can be enabled and/or disabled via registers pmc_pcer and pmc_pcdr. depending on the system used, 26 peripheral clocks can be enabled or disabled. the pmc_pcsr provides a clear view as to which peripheral clock is enabled. note: each enabled peripheral clock corresponds to master clock. code examples: write_register(pmc_pcer,0x00000110) peripheral clocks 4 and 8 are enabled. write_register(pmc_pcdr,0x00000010) peripheral clock 4 is disabled.
161 6042e?atarm?14-dec-06 at91sam7a3 preliminary 24.8 clock switching details 24.8.1 master clock switching timings table 24-1 gives the worst case timings required fo r the master clock to switch from one selected clock to another one. this is in the event that the prescaler is de-activated. when the prescaler is activated, an additional time of 64 cl ock cycles of the new selected clock has to be added. 24.8.2 clock switching waveforms figure 24-3. switch master clock from slow clock to pll clock table 24-1. clock switching timings (worst case) from main clock slck pll clock to main clock ? 4 x slck + 2.5 x main clock 3 x pll clock + 4 x slck + 1 x main clock slck 0.5 x main clock + 4.5 x slck ? 3 x pll clock + 5 x slck pll clock 0.5 x main clock + 4 x slck + pllcount x slck + 2.5 x pllx clock 2.5 x pll clock + 5 x slck + pllcount x slck 2.5 x pll clock + 4 x slck + pllcount x slck slow clock lock mckrdy master clock write pmc_mckr pll clock
162 6042e?atarm?14-dec-06 at91sam7a3 preliminary figure 24-4. switch master clock from main clock to slow clock figure 24-5. change pll programming slow clock main clock mckrdy master clock write pmc_mckr main clock main clock pll clock lock mckrdy master clock write ckgr_pllr
163 6042e?atarm?14-dec-06 at91sam7a3 preliminary figure 24-6. programmable clock output programming pll clock pckrdy pckx output write pmc_pckx write pmc_scer write pmc_scdr pckx is disabled pckx is enabled pll clock is selected
164 6042e?atarm?14-dec-06 at91sam7a3 preliminary 24.9 power management contro ller (pmc) user interface table 24-2. register mapping offset register name access reset value 0x0000 system clock enable register pmc_scer write-only ? 0x0004 system clock disable register pmc_scdr write-only ? 0x0008 system clock status register pmc _scsr read-only 0x01 0x000c reserved ? ? ? 0x0010 peripheral clock enable register pmc _pcer write-only ? 0x0014 peripheral clock disable register pmc_pcdr write-only ? 0x0018 peripheral clock status register pmc_pcsr read-only 0x0 0x0020 main oscillator register ckgr_mor read/write 0x0 0x0024 main clock frequency register ckgr_mcfr read-only 0x0 0x0028 reserved ? ? ? 0x002c pll register ckgr_pllr read/write 0x3f00 0x0030 master clock register pmc_mckr read/write 0x0 0x0038 reserved ? ? ? 0x003c reserved ? ? ? 0x0040 programmable clock 0 register pmc_pck0 read/write 0x0 0x0044 programmable clock 1 register pmc_pck1 read/write 0x0 ... ... ... ... ... 0x0060 interrupt enable register pmc_ier write-only -- 0x0064 interrupt disable register pmc_idr write-only -- 0x0068 status register pmc_sr read-only 0x08 0x006c interrupt mask register pmc_imr read-only 0x0 0x0070 - 0x007c reserved ? ? ?
165 6042e?atarm?14-dec-06 at91sam7a3 preliminary 24.9.1 pmc system clock enable register register name: pmc_scer access type: write-only pck: processor clock enable 0 = no effect. 1 = enables the processor clock. udp: usb device port clock enable 0 = no effect. 1 = enables the 48 mhz clock of the usb device port. pckx: programmable clock x output enable 0 = no effect. 1 = enables the corresponding programmable clock output. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ????pck3pck2pck1pck0 76543210 udp??????pck
166 6042e?atarm?14-dec-06 at91sam7a3 preliminary 24.9.2 pmc system clock disable register register name: pmc_scdr access type: write-only pck: processor clock disable 0 = no effect. 1 = disables the processor clock. this is used to enter the processor in idle mode. udp: usb device port clock disable 0 = no effect. 1 = disables the 48 mhz clock of the usb device port. pckx: programmable clock x output disable 0 = no effect. 1 = disables the corresponding programmable clock output. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ????pck3pck2pck1pck0 76543210 udp??????pck
167 6042e?atarm?14-dec-06 at91sam7a3 preliminary 24.9.3 pmc system clock status register register name: pmc_scsr access type: read-only pck: processor clock status 0 = the processor clock is disabled. 1 = the processor clock is enabled. udp: usb device port clock status 0 = the 48 mhz clock (udpck) of th e usb device port is disabled. 1 = the 48 mhz clock (udpck) of the usb device port is enabled. pckx: programmable clock x output status 0 = the corresponding programmable clock output is disabled. 1 = the corresponding programmable clock output is enabled. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ????pck3pck2pck1pck0 76543210 udp??????pck
168 6042e?atarm?14-dec-06 at91sam7a3 preliminary 24.9.4 pmc peripheral clock enable register register name: pmc_pcer access type: write-only pidx: peripheral clock x enable 0 = no effect. 1 = enables the corresponding peripheral clock. note: pid2 to pid31 refer to identifiers as defined in the section ?peripheral identifiers ? in the product datasheet. note: programming the control bits of the peripheral id that ar e not implemented has no effect on the behavior of the pmc. 31 30 29 28 27 26 25 24 pid31 pid30 pid29 pid28 pid27 pid26 pid25 pid24 23 22 21 20 19 18 17 16 pid23 pid22 pid21 pid20 pid19 pid18 pid17 pid16 15 14 13 12 11 10 9 8 pid15 pid14 pid13 pid12 pid11 pid10 pid9 pid8 76543210 pid7 pid6 pid5 pid4 pid3 pid2 - -
169 6042e?atarm?14-dec-06 at91sam7a3 preliminary 24.9.5 pmc peripheral clock disable register register name: pmc_pcdr access type: write-only pidx: peripheral clock x disable 0 = no effect. 1 = disables the corresponding peripheral clock. note: pid2 to pid31 refer to identifiers as defined in the section ?peripheral identifiers ? in the product datasheet. 31 30 29 28 27 26 25 24 pid31 pid30 pid29 pid28 pid27 pid26 pid25 pid24 23 22 21 20 19 18 17 16 pid23 pid22 pid21 pid20 pid19 pid18 pid17 pid16 15 14 13 12 11 10 9 8 pid15 pid14 pid13 pid12 pid11 pid10 pid9 pid8 76543210 pid7 pid6 pid5 pid4 pid3 pid2 - -
170 6042e?atarm?14-dec-06 at91sam7a3 preliminary 24.9.6 pmc peripheral clock status register register name: pmc_pcsr access type: read-only pidx: peripheral clock x status 0 = the corresponding peripheral clock is disabled. 1 = the corresponding peripheral clock is enabled. note: pid2 to pid31 refer to identifiers as defined in the section ?peripheral identifiers ? in the product datasheet. 31 30 29 28 27 26 25 24 pid31 pid30 pid29 pid28 pid27 pid26 pid25 pid24 23 22 21 20 19 18 17 16 pid23 pid22 pid21 pid20 pid19 pid18 pid17 pid16 15 14 13 12 11 10 9 8 pid15 pid14 pid13 pid12 pid11 pid10 pid9 pid8 76543210 pid7 pid6 pid5 pid4 pid3 pid2 ? ?
171 6042e?atarm?14-dec-06 at91sam7a3 preliminary 24.9.7 pmc clock generator main oscillator register register name: ckgr_mor access type: read/write moscen: main oscillator enable a crystal must be connected between xin and xout. 0 = the main oscillator is disabled. 1 = the main oscillator is enabl ed. oscbypass must be set to 0. when moscen is set, the moscs flag is set once the main oscillator startup time is achieved. oscbypass: oscillator bypass 0 = no effect. 1 = the main oscillator is bypassed. moscen must be set to 0. an exter nal clock must be connected on xin. when oscbypass is set, th e moscs flag in pmc_sr is automatically set. clearing moscen and oscbypass bits allows resetting the moscs flag. oscount: main oscillator start-up time specifies the number of slow clock cycles multip lied by 8 for the main o scillator start-up time. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 oscount 76543210 ??????oscbypassmoscen
172 6042e?atarm?14-dec-06 at91sam7a3 preliminary 24.9.8 pmc clock generator main clock frequency register register name: ckgr_mcfr access type: read-only mainf: main clock frequency gives the number of main clock cycles within 16 slow clock periods. mainrdy: main clock ready 0 = mainf value is not valid or the main oscillator is disabled. 1 = the main oscillator has been enabled pr eviously and mainf value is available. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????mainrdy 15 14 13 12 11 10 9 8 mainf 76543210 mainf
173 6042e?atarm?14-dec-06 at91sam7a3 preliminary 24.9.9 pmc clock generator pll register register name: ckgr_pllr access type: read/write possible limitations on pll input frequencies and multiplier factors should be checked before using the pmc. div: divider pllcount: pll counter specifies the number of slow clock cycles before the lo ck bit is set in pmc_sr after ckgr_pllr is written. out: pll clock frequency range to optimize clock performance, this field must be programmed as specified in ?pll characteristics? in the electrical char- acteristics section of the product datasheet. mul: pll multiplier 0 = the pll is deactivated. 1 up to 2047 = the pll clock frequency is the pll input frequency multiplied by mul+ 1. usbdiv: divider for usb clock 31 30 29 28 27 26 25 24 ? ? usbdiv ? mul 23 22 21 20 19 18 17 16 mul 15 14 13 12 11 10 9 8 out pllcount 76543210 div div divider selected 0 divider output is 0 1 divider is bypassed 2 - 255 divider output is the selected clock divided by div. usbdiv divider for usb clock(s) 0 0 divider output is pll clock output. 0 1 divider output is pll clock output divided by 2. 1 0 divider output is pll clock output divided by 4. 1 1 reserved.
174 6042e?atarm?14-dec-06 at91sam7a3 preliminary 24.9.10 pmc master clock register register name: pmc_mckr access type: read/write css: master clock selection pres: processor clock prescaler 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ????? ? 15 14 13 12 11 10 9 8 ?????? ? 76543210 ? ? ? pres css css clock source selection 0 0 slow clock is selected 0 1 main clock is selected 10reserved 1 1 pll clock is selected. pres processor clock 0 0 0 selected clock 0 0 1 selected clock divided by 2 0 1 0 selected clock divided by 4 0 1 1 selected clock divided by 8 1 0 0 selected clock divided by 16 1 0 1 selected clock divided by 32 1 1 0 selected clock divided by 64 111reserved
175 6042e?atarm?14-dec-06 at91sam7a3 preliminary 24.9.11 pmc programmable clock register register name: pmc_pckx access type: read/write css: master clock selection pres: programmable clock prescaler 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ????? ? 15 14 13 12 11 10 9 8 ???????? 76543210 ? ? ? pres css css clock source selection 0 0 slow clock is selected 0 1 main clock is selected 10reserved 1 1 pll clock is selected pres programmable clock 0 0 0 selected clock 0 0 1 selected clock divided by 2 0 1 0 selected clock divided by 4 0 1 1 selected clock divided by 8 1 0 0 selected clock divided by 16 1 0 1 selected clock divided by 32 1 1 0 selected clock divided by 64 111reserved
176 6042e?atarm?14-dec-06 at91sam7a3 preliminary 24.9.12 pmc interrupt enable register register name: pmc_ier access type: write-only moscs: main oscillator status interrupt enable lock: pll lock interrupt enable mckrdy: master clock ready interrupt enable pckrdyx: programmable clock ready x interrupt enable 0 = no effect. 1 = enables the corresponding interrupt. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ?????pckrdy2pckrdy1pckrdy0 76543210 ? ?? ? mckrdy lock ? moscs
177 6042e?atarm?14-dec-06 at91sam7a3 preliminary 24.9.13 pmc interrupt disable register register name: pmc_idr access type: write-only moscs: main oscillator status interrupt disable lock: pll lock interrupt disable mckrdy: master clock ready interrupt disable pckrdyx: programmable clock ready x interrupt disable 0 = no effect. 1 = disables the corresponding interrupt. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ?????pckrdy2pckrdy1pckrdy0 76543210 ? ???mckrdy lock ? moscs
178 6042e?atarm?14-dec-06 at91sam7a3 preliminary 24.9.14 pmc status register register name: pmc_sr access type: read-only moscs: moscs flag status 0 = main oscillator is not stabilized. 1 = main oscillator is stabilized. lock: pll lock status 0 = pll is not locked 1 = pll is locked. mckrdy: master clock status 0 = master clock is not ready. 1 = master clock is ready. pckrdyx: programmable clock ready status 0 = programmable clock x is not ready. 1 = programmable clock x is ready. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ?????pckrdy2pckrdy1pckrdy0 76543210 ????mckrdy lock ? moscs
179 6042e?atarm?14-dec-06 at91sam7a3 preliminary 24.9.15 pmc interrupt mask register register name: pmc_imr access type: read-only moscs: main oscillator status interrupt mask lock: pll lock interrupt mask mckrdy: master clock ready interrupt mask pckrdyx: programmable clock ready x interrupt mask 0 = the corresponding interrupt is enabled. 1 = the corresponding interrupt is disabled. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ?????pckrdy2pckrdy1pckrdy0 76543210 ? ???mckrdy lock ? moscs
180 6042e?atarm?14-dec-06 at91sam7a3 preliminary
181 6042e?atarm?14-dec-06 at91sam7a3 preliminary 25. debug unit (dbgu 25.1 overview the debug unit provides a single entry point fr om the processor for access to all the debug capabilities of atmel?s arm-based systems. the debug unit features a two-pin uart that can be used for several debug and trace pur- poses and offers an ideal medium for in-situ programming solutions and debug monitor communications. moreover, the association with two peripheral data controller channels per- mits packet handling for these tasks with processor time reduced to a minimum. the debug unit also makes the debug comm unication channel (dcc) signals provided by the in-circuit emulator of the arm processor visi ble to the software. these signals indicate the status of the dcc read and write registers and generate an interrupt to the arm processor, making possible the handling of the dcc under interrupt control. chip identifier registers permit recognition of the device and its revision. these registers inform as to the sizes and types of the on-chip memories, as well as the set of embedded peripherals.
182 6042e?atarm?14-dec-06 at91sam7a3 preliminary 25.2 block diagram figure 25-1. debug unit functional block diagram figure 25-2. debug unit application example peripheral dma controller baud rate generator dcc handler transmit receive chip id interrupt control peripheral bridge parallel input/ output dtxd drxd power management controller arm processor commrx commtx mck ntrst dbgu_irq apb debug unit power-on reset table 25-1. debug unit pin description pin name description type drxd debug receive data input dtxd debug transmit data output debug unit rs232 drivers programming tool trace console debug console boot program debug monitor trace manager
183 6042e?atarm?14-dec-06 at91sam7a3 preliminary 25.3 product dependencies 25.3.1 i/o lines depending on product integration, the debug unit pins may be multiplexed with pio lines. in this case, the programmer must first configure the corresponding pio controller to enable i/o lines operations of the debug unit. 25.3.2 power management depending on product integration, the debug unit clock may be controllable through the power management controller. in this case, the programmer must first configure the pmc to enable the debug unit clock. usually, the perip heral identifier used for this purpose is 1. 25.3.3 interrupt source depending on product integration, the debug unit interrupt line is connected to one of the interrupt sources of the advanced interrupt controller. interrupt handling requires program- ming of the aic before configuring the deb ug unit. usually, the debug unit interrupt line connects to the interrupt source 1 of the aic, which may be shared with the real-time clock, the system timer interrupt lines and other system peripheral interrupts, as shown in figure 25- 1 . this sharing requires the programmer to determine the source of the interrupt when the source 1 is triggered. 25.4 uart operations the debug unit operates as a uart, (asynchronous mode only) and supports only 8-bit char- acter handling (with parity). it has no clock pin. the debug unit's uart is made up of a receiver and a transmitter that operate independently, and a common baud rate generator. receiver timeout and transmitter time guard are not implemented. however, all the implemented features are compatible with those of a standard usart. 25.4.1 baud rate generator the baud rate generator provides the bit period clock named baud rate clock to both the receiver and the transmitter. the baud rate clock is the master clock divided by 16 times the value (cd) written in dbgu_brgr (baud rate generator register). if dbgu_brgr is set to 0, the baud rate clock is disabled and the debug unit's uart remains inactive. the maximum allowable baud rate is master clock divided by 16. the minimu m allowable baud rate is master clock divided by (16 x 65536). baud rate mck 16 cd --------------------- =
184 6042e?atarm?14-dec-06 at91sam7a3 preliminary figure 25-3. baud rate generator 25.4.2 receiver 25.4.2.1 receiver rese t, enable and disable after device reset, the debug unit receiv er is disabled and must be enabled before being used. the receiver can be enabled by writing th e control register dbgu_cr with the bit rxen at 1. at this command, the receiver starts looking for a start bit. the programmer can disable the receiver by writ ing dbgu_cr with the bit rxdis at 1. if the receiver is waiting for a start bit, it is immediately stopped. however, if the receiver has already detected a start bit and is receiving the data, it waits for the stop bit before actually stopping its operation. the programmer can also put the receiver in its reset state by writing dbgu_cr with the bit rstrx at 1. in doing so, the receiver immediately stops its current operations and is disabled, whatever its current state. if rstrx is applied when data is being processed, this data is lost. 25.4.2.2 start detection and data sampling the debug unit only supports asynchronous operations, and this affects only its receiver. the debug unit receiver detects the start of a received character by sampling the drxd signal until it detects a valid start bit. a low level (space) on drxd is in terpreted as a valid start bit if it is detected for more than 7 cycles of the sampling clock, which is 16 times the baud rate. hence, a space that is longer than 7/16 of the bi t period is detected as a valid start bit. a space which is 7/16 of a bit period or shorter is ignored and the receiver continues to wait for a valid start bit. when a valid start bit has been detected, the receiver samples the drxd at the theoretical midpoint of each bit. it is assumed that each bit lasts 16 cycles of the sampling clock (1-bit period) so the bit sampling point is eight cycles (0 .5-bit period) after the start of the bit. the first sampling point is therefore 24 cycles (1.5-bit periods) after the falling edge of the start bit was detected. each subsequent bit is sampled 16 cycles (1-bit period) after the previous one. mck 16-bit counter 0 baud rate clock cd cd out divide by 16 0 1 >1 receiver sampling clock
185 6042e?atarm?14-dec-06 at91sam7a3 preliminary figure 25-4. start bit detection figure 25-5. character reception 25.4.2.3 receiver ready when a complete character is received, it is transferred to the dbgu_rhr and the rxrdy status bit in dbgu_sr (status register) is set. the bit rxrdy is automatically cleared when the receive holding register dbgu_rhr is read. figure 25-6. receiver ready 25.4.2.4 receiver overrun if dbgu_rhr has not been read by the software (or the peripheral data controller) since the last transfer, the rxrdy bit is still set and a new character is received, th e ovre status bit in dbgu_sr is set. ovre is cleared when the soft ware writes the control register dbgu_cr with the bit rststa (reset status) at 1. figure 25-7. receiver overrun 25.4.2.5 parity error each time a character is received, the receiver calculates the parity of the received data bits, in accordance with the field par in dbgu_mr. it then compares the result with the received sampling clock drxd true start detection d0 baud rate clock d0 d1 d2 d3 d4 d5 d6 d7 drxd true start detection sampling parity bit stop bit example: 8-bit, parity enabled 1 stop 1 bit period 0.5 bit period d0 d1 d2 d3 d4 d5 d6 d7 p s s d0 d1 d2 d3 d4 d5 d6 d7 p drxd read dbgu_rhr rxrdy d0 d1 d2 d3 d4 d5 d6 d7 p s s d0 d1 d2 d3 d4 d5 d6 d7 p drxd rststa rxrdy ovre stop stop
186 6042e?atarm?14-dec-06 at91sam7a3 preliminary parity bit. if different, the parity error bit pare in dbgu_sr is set at the same time the rxrdy is set. the parity bit is cleared when the control register dbgu_ cr is written with the bit rststa (reset status) at 1. if a new char acter is received before the reset status com- mand is written, the pare bit remains at 1. figure 25-8. parity error 25.4.2.6 receiver framing error when a start bit is detected, it generates a c haracter reception when all the data bits have been sampled. the stop bit is also sampled and when it is detected at 0, the frame (framing error) bit in dbgu_sr is set at the same ti me the rxrdy bit is set. the bit frame remains high until the control register dbgu_cr is written with the bit rststa at 1. figure 25-9. receiver framing error 25.4.3 transmitter 25.4.3.1 transmitter reset, enable and disable after device reset, the debug unit transmitter is disabled and it must be enabled before being used. the transmitter is enabled by writing the control register dbgu_cr with the bit txen at 1. from this command, the transmitter waits for a character to be written in the transmit hold- ing register dbgu_thr before actually starting the transmission. the programmer can disable the transmitter by writing dbgu_cr with the bit txdis at 1. if the transmitter is not operating, it is immediately stopped. however, if a character is being pro- cessed into the shift register and/or a character has been written in the transmit holding register, the characters are completed before the transmitter is actually stopped. the programmer can also put the transmitter in its reset state by writing the dbgu_cr with the bit rsttx at 1. this immediately stops the transmitter, whether or not it is processing characters. 25.4.3.2 transmit format the debug unit transmitter drives the pin dtxd at the baud rate clock speed. the line is driven depending on the format defined in the mode register and the data stored in the shift register. one start bit at level 0, then the 8 data bits, from the lowest to the highest bit, one optional parity bit and one stop bit at 1 are consecutively shifted out as shown on the following stop d0 d1 d2 d3 d4 d5 d6 d7 p s drxd rststa rxrdy pare wrong parity bit d0 d1 d2 d3 d4 d5 d6 d7 p s drxd rststa rxrdy frame stop bit detected at 0 stop
187 6042e?atarm?14-dec-06 at91sam7a3 preliminary figure. the field pare in the mode register db gu_mr defines whether or not a parity bit is shifted out. when a parity bit is enabled, it can be selected between an odd parity, an even parity, or a fixed space or mark bit. figure 25-10. character transmission 25.4.3.3 transmitter control when the transmitter is enabled, the bit txrdy (transmitter ready) is set in the status regis- ter dbgu_sr. the transmission starts when the programmer writes in the transmit holding register dbgu_thr, and after the written character is transferred from dbgu_thr to the shift register. the bit txrdy re mains high until a second character is written in dbgu_thr. as soon as the first character is completed, th e last character written in dbgu_thr is trans- ferred into the shift register and txrdy rises again, showing that the holding register is empty. when both the shift register and the dbgu_thr are empty, i.e., all the characters written in dbgu_thr have been processed, the bit txempty rises after the last stop bit has been completed. figure 25-11. transmitter control 25.4.4 peripheral data controller both the receiver and the transmitter of the debug unit's uart are generally connected to a peripheral data controller (pdc) channel. the peripheral data controller channels are programmed via registers that are mapped within the debug unit user interface from the offset 0x100. the status bits are reported in the debug unit status register dbgu_sr and can generate an interrupt. d0 d1 d2 d3 d4 d5 d6 d7 dtxd start bit parity bit stop bit example: parity enabled baud rate clock dbgu_thr shift register dtxd txrdy txempty data 0 data 1 data 0 data 0 data 1 data 1 s s p p write data 0 in dbgu_thr write data 1 in dbgu_thr stop stop
188 6042e?atarm?14-dec-06 at91sam7a3 preliminary the rxrdy bit triggers the pdc channel data transfer of the receiver. this results in a read of the data in dbgu_rhr. the txrdy bit trigger s the pdc channel data transfer of the trans- mitter. this results in a write of a data in dbgu_thr. 25.4.5 test modes the debug unit supports three tests modes. these modes of operation are programmed by using the field chmode (channel mode) in the mode register dbgu_mr. the automatic echo mode allows bit-by-bit retransmission. when a bit is received on the drxd line, it is sent to the dtxd line. the transmitter operates normally, but has no effect on the dtxd line. the local loopback mode allows the transmitt ed characters to be received. dtxd and drxd pins are not used and the output of the transmitter is internally connected to the input of the receiver. the drxd pin level has no effect and th e dtxd line is held high , as in idle state. the remote loopback mode directly connects th e drxd pin to the dtxd line. the transmit- ter and the receiver are disabled and have no effect. this mode allows a bit-by-bit retransmission. figure 25-12. test modes 25.4.6 debug communication channel support the debug unit handles the signals commrx and commtx that come from the debug communication channel of the arm processor and are driven by the in-circuit emulator. receiver transmitter disabled rxd txd receiver transmitter disabled rxd txd v dd disabled receiver transmitter disabled rxd txd disabled automatic echo local loopback remote loopback v dd
189 6042e?atarm?14-dec-06 at91sam7a3 preliminary the debug communication channel contains two registers that are accessible through the ice breaker on the jtag side and through the coprocessor 0 on the arm processor side. as a reminder, the following instructions are used to read and write the debug communication channel: mrc p14, 0, rd, c1, c0, 0 returns the debug communication data read register into rd mcr p14, 0, rd, c1, c0, 0 writes the value in rd to the debug communication data write register. the bits commrx and commtx, which indicate, respectively, that the read register has been written by the debugger but not yet read by the processor, and that the write register has been written by the processor and not yet read by the debugger, are wired on the two highest bits of the status register dbgu_sr. these bits can generate an interrupt. this feature per- mits handling under interrupt a debug link between a debug monitor running on the target system and a debugger. 25.4.7 chip identifier the debug unit features two chip identifier registers, dbgu_cidr (chip id register) and dbgu_exid (extension id). both registers contain a hard-wired value that is read-only. the first register contains the following fields: ext - shows the use of the extension identifier register nvptyp and nvpsiz - identifies the type of embedded non-volatile memory and its size arch - identifies the set of embedded peripheral sramsiz - indicates the size of the embedded sram eproc - indicates the embedded arm processor version - gives the revision of the silicon the second register is device-dependent and reads 0 if the bit ext is 0.
190 6042e?atarm?14-dec-06 at91sam7a3 preliminary 25.5 debug unit user interface table 25-2. debug unit memory map offset register name access reset value 0x0000 control register dbgu_cr write-only ? 0x0004 mode register dbgu_mr read/write 0x0 0x0008 interrupt enable register dbgu_ier write-only ? 0x000c interrupt disable register dbgu_idr write-only ? 0x0010 interrupt mask register dbgu_imr read-only 0x0 0x0014 status register dbgu_sr read-only ? 0x0018 receive holding register dbgu_rhr read-only 0x0 0x001c transmit holding register dbgu_thr write-only ? 0x0020 baud rate generator register dbgu_brgr read/write 0x0 0x0024 - 0x003c reserved ? ? ? 0x0040 chip id register dbgu_cidr read-only ? 0x0044 chip id extension register dbgu_exid read-only ? 0x0048 reserved ? ? ? 0x004c - 0x00fc reserved ? ? ? 0x0100 - 0x0124 pdc area ? ? ?
191 6042e?atarm?14-dec-06 at91sam7a3 preliminary 25.5.1 debug unit control register name: dbgu_cr access type: write-only rstrx: reset receiver 0 = no effect. 1 = the receiver logic is reset and disabled. if a ch aracter is being received, the reception is aborted. rsttx: reset transmitter 0 = no effect. 1 = the transmitter logic is reset and disabled. if a character is being transmitted, the transmission is aborted. rxen: receiver enable 0 = no effect. 1 = the receiver is enabled if rxdis is 0. rxdis: receiver disable 0 = no effect. 1 = the receiver is disabled. if a character is being processe d and rstrx is not set, the character is completed before the receiver is stopped. txen: transmitter enable 0 = no effect. 1 = the transmitter is ena bled if txdis is 0. txdis: transmitter disable 0 = no effect. 1 = the transmitter is disabled. if a character is being processed and a charac ter has been written the dbgu_thr and rsttx is not set, both characters are completed before the transmitter is stopped. rststa: reset status bits 0 = no effect. 1 = resets the status bits pare, frame and ovre in the dbgu_sr. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ??????? rststa 76543210 txdis txen rxdis rxen rsttx rstrx ??
192 6042e?atarm?14-dec-06 at91sam7a3 preliminary 25.5.2 debug unit mode register name: dbgu_mr access type: read/write par: parity type chmode: channel mode 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 chmode ?? pa r ? 76543210 ???????? par parity type 0 0 0 even parity 001odd parity 0 1 0 space: parity forced to 0 0 1 1 mark: parity forced to 1 1 x x no parity chmode mode description 00normal mode 0 1 automatic echo 1 0 local loopback 1 1 remote loopback
193 6042e?atarm?14-dec-06 at91sam7a3 preliminary 25.5.3 debug unit interrupt enable register name: dbgu_ier access type: write-only rxrdy: enable rxrdy interrupt txrdy: enable txrdy interrupt endrx: enable end of receive transfer interrupt endtx: enable end of transmit interrupt ovre: enable overrun error interrupt frame: enable framing error interrupt pare: enable parity error interrupt txempty: enable txempty interrupt txbufe: enable buffer empty interrupt rxbuff: enable buffer full interrupt commtx: enable commtx (from arm) interrupt commrx: enable commrx (from arm) interrupt 0 = no effect. 1 = enables the corresponding interrupt. 31 30 29 28 27 26 25 24 commrx commtx ?????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ??? rxbuff txbufe ? txempty ? 76543210 pare frame ovre endtx endrx ? txrdy rxrdy
194 6042e?atarm?14-dec-06 at91sam7a3 preliminary 25.5.4 debug unit interrupt disable register name: dbgu_idr access type: write-only rxrdy: disable rxrdy interrupt txrdy: disable txrdy interrupt endrx: disable end of receive transfer interrupt endtx: disable end of transmit interrupt ovre: disable overrun error interrupt frame: disable framing error interrupt pare: disable parity error interrupt txempty: disable txempty interrupt txbufe: disable buffer empty interrupt rxbuff: disable buffer full interrupt commtx: disable commtx (from arm) interrupt commrx: disable commrx (from arm) interrupt 0 = no effect. 1 = disables the corresponding interrupt. 31 30 29 28 27 26 25 24 commrx commtx ?????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ??? rxbuff txbufe ? txempty ? 76543210 pare frame ovre endtx endrx ? txrdy rxrdy
195 6042e?atarm?14-dec-06 at91sam7a3 preliminary 25.5.5 debug unit interrupt mask register name: dbgu_imr access type: read-only rxrdy: mask rxrdy interrupt txrdy: disable txrdy interrupt endrx: mask end of receive transfer interrupt endtx: mask end of transmit interrupt ovre: mask overrun error interrupt frame: mask framing error interrupt pare: mask parity error interrupt txempty: mask txempty interrupt txbufe: mask txbufe interrupt rxbuff: mask rxbuff interrupt commtx: mask commtx interrupt commrx: mask commrx interrupt 0 = the corresponding interrupt is disabled. 1 = the corresponding interrupt is enabled. 31 30 29 28 27 26 25 24 commrx commtx ?????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ??? rxbuff txbufe ? txempty ? 76543210 pare frame ovre endtx endrx ? txrdy rxrdy
196 6042e?atarm?14-dec-06 at91sam7a3 preliminary 25.5.6 debug unit status register name: dbgu_sr access type: read-only rxrdy: receiver ready 0 = no character has been received since the last re ad of the dbgu_rhr or the receiver is disabled. 1 = at least one complete character has been received, transferred to dbgu_rhr and not yet read. txrdy: transmitter ready 0 = a character has been written to dbgu_thr and not yet transferred to the shift register, or the transmitter is disabled. 1 = there is no character written to dbgu_thr not yet transferred to the shift register. endrx: end of receiver transfer 0 = the end of transfer signal from the receiver peripheral data controller channel is inactive. 1 = the end of transfer signal from the receiver peripheral data controller channel is active. endtx: end of transmitter transfer 0 = the end of transfer signal from the transmitter peripheral data controller channel is inactive. 1 = the end of transfer signal from the transmitter peripheral data controller channel is active. ovre: overrun error 0 = no overrun error has occurred since the last rststa. 1 = at least one overrun error has occurred since the last rststa. frame: framing error 0 = no framing error has occurred since the last rststa. 1 = at least one framing error has occurred since the last rststa. pare: parity error 0 = no parity error has occurred since the last rststa. 1 = at least one parity error has occurred since the last rststa. txempty: transmitter empty 0 = there are characters in dbgu_thr, or characters being processed by the transmitter, or the transmitter is disabled. 1 = there are no characters in dbgu_thr and there ar e no characters being processed by the transmitter. txbufe: transmission buffer empty 0 = the buffer empty signal from the transmitter pdc channel is inactive. 1 = the buffer empty signal from the transmitter pdc channel is active. rxbuff: receive buffer full 0 = the buffer full signal from the receiver pdc channel is inactive. 1 = the buffer full signal from the receiver pdc channel is active. 31 30 29 28 27 26 25 24 commrx commtx ?????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ??? rxbuff txbufe ? txempty ? 76543210 pare frame ovre endtx endrx ? txrdy rxrdy
197 6042e?atarm?14-dec-06 at91sam7a3 preliminary commtx: debug communication channel write status 0 = commtx from the arm processor is inactive. 1 = commtx from the arm processor is active. commrx: debug communication channel read status 0 = commrx from the arm processor is inactive. 1 = commrx from the arm processor is active.
198 6042e?atarm?14-dec-06 at91sam7a3 preliminary 25.5.7 debug unit receiver holding register name: dbgu_rhr access type: read-only rxchr: received character last received character if rxrdy is set. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ???????? 76543210 rxchr
199 6042e?atarm?14-dec-06 at91sam7a3 preliminary 25.5.8 debug unit transmit holding register name: dbgu_thr access type: write-only txchr: character to be transmitted next character to be transmitted after the current character if txrdy is not set. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ???????? 76543210 txchr
200 6042e?atarm?14-dec-06 at91sam7a3 preliminary 25.5.9 debug unit baud ra te generator register name: dbgu_brgr access type: read/write cd: clock divisor 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 cd 76543210 cd cd baud rate clock 0 disabled 1mck 2 to 65535 mck / (cd x 16)
201 6042e?atarm?14-dec-06 at91sam7a3 preliminary 25.5.10 debug unit chip id register name: dbgu_cidr access type: read-only version: version of the device eproc: embedded processor nvpsiz: nonvolatile program memory size 31 30 29 28 27 26 25 24 ext nvptyp arch 23 22 21 20 19 18 17 16 arch sramsiz 15 14 13 12 11 10 9 8 nvpsiz2 nvpsiz 76543210 eproc version eproc processor 0 0 1 arm946es ? 0 1 0 arm7tdmi ? 100arm920t ? 1 0 1 arm926ejs ? nvpsiz size 0000none 00018k bytes 001016k bytes 001132k bytes 0100reserved 010164k bytes 0110reserved 0111128k bytes 1000reserved 1001256k bytes 1010512k bytes 1011reserved 11001024k bytes 1101reserved 11102048k bytes 1111reserved
202 6042e?atarm?14-dec-06 at91sam7a3 preliminary nvpsiz2 second nonvolatile program memory size sramsiz: internal sram size nvpsiz2 size 0000none 00018k bytes 001016k bytes 001132k bytes 0100reserved 010164k bytes 0110reserved 0111128k bytes 1000reserved 1001256k bytes 1010512k bytes 1011reserved 11001024k bytes 1101reserved 11102048k bytes 1111reserved sramsiz size 0000reserved 00011k bytes 00102k bytes 0011reserved 0100112k bytes 01014k bytes 011080k bytes 0111160k bytes 10008k bytes 100116k bytes 101032k bytes 101164k bytes 1100128k bytes 1101256k bytes 111096k bytes 1111512k bytes
203 6042e?atarm?14-dec-06 at91sam7a3 preliminary arch: architecture identifier nvptyp: nonvolatile program memory type ext: extension flag 0 = chip id has a single register definition without extension 1 = an extended chip id exists. arch architecture hex bin 0x19 0001 1001 at91sam9xx series 0x29 0010 1001 at91sam9xexx series 0x34 0011 0100 at91x34 series 0x39 0011 1001 cap9 series 0x40 0100 0000 at91x40 series 0x42 0100 0010 at91x42 series 0x55 0101 0101 at91x55 series 0x60 0101 0000 at91sam7axx series 0x63 0110 0011 at91x63 series 0x70 0111 0000 at91sam7sxx series 0x71 0111 0001 at91sam7xcxx series 0x72 0111 0010 at91sam7sexx series 0x73 0111 0011 at91sam7lxx series 0x75 0111 0101 at91sam7xxx series 0x92 1001 0010 at91x92 series 0xf0 1111 0001 at75cxx series nvptyp memory 000rom 0 0 1 romless or on-chip flash 1 0 0 sram emulating rom 0 1 0 embedded flash memory 011 rom and embedded flash memory nvpsiz is rom size nvpsiz2 is flash size
204 6042e?atarm?14-dec-06 at91sam7a3 preliminary 25.5.11 debug unit chip id extension register name: dbgu_exid access type: read-only exid: chip id extension reads 0 if the bit ext in dbgu_cidr is 0. 31 30 29 28 27 26 25 24 exid 23 22 21 20 19 18 17 16 exid 15 14 13 12 11 10 9 8 exid 76543210 exid
205 6042e?atarm?14-dec-06 at91sam7a3 preliminary 26. parallel input outp ut controller (pio) 26.1 overview the parallel input/output controller (pio) manages up to 32 fully programmable input/output lines. each i/o line may be dedicated as a general-purpose i/o or be assigned to a function of an embedded peripheral. this assures effective optimization of the pins of a product. each i/o line is associated with a bit number in all of the 32-bit registers of the 32-bit wide user interface. each i/o line of the pio controller features: an input change interrupt enabling level change detection on any i/o line. a glitch filter providing rejection of pulses lower than one-half of clock cycle. multi-drive capability similar to an open drain i/o line. control of the pull-up of the i/o line. input visibility and output control. the pio controller also features a synchronous output providing up to 32 bits of data output in a single write operation.
206 6042e?atarm?14-dec-06 at91sam7a3 preliminary 26.2 block diagram figure 26-1. block diagram figure 26-2. application block diagram embedded peripheral embedded peripheral pio interrupt pio controller up to 32 pins pmc up to 32 peripheral ios up to 32 peripheral ios pio clock apb aic data, enable pin 31 pin 1 pin 0 data, enable on-chip peripherals pio controller on-chip peripheral drivers control & command driver keyboard driver keyboard driver general purpose i/os external devices
207 6042e?atarm?14-dec-06 at91sam7a3 preliminary 26.3 product dependencies 26.3.1 pin multiplexing each pin is configurable, according to product definition as either a general-purpose i/o line only, or as an i/o line multiplexed with one or two peripheral i/os. as the multiplexing is hard- ware-defined and thus product-dependent, the hardware designer and programmer must carefully determine the configuration of the pio controllers required by their application. when an i/o line is general-purpose only, i.e. not multiplexed with any peripheral i/o, programming of the pio controller regarding the assignment to a peripheral has no effect and only the pio con- troller can control how the pin is driven by the product. 26.3.2 external interrupt lines the interrupt signals fiq and irq0 to irqn are most generally multiplexed through the pio controllers. however, it is not necessary to assign the i/o line to the interrupt function as the pio controller has no effect on inputs and the interrupt lines (fiq or irqs) are used only as inputs. 26.3.3 power management the power management controller controls the pio controller clock in order to save power. writing any of the registers of the user interface does not require the pio controller clock to be enabled. this means that the configuration of the i/o lines does not require the pio controller clock to be enabled. however, when the clock is disabled, not all of t he features of the pio controller are available. note that the input change interrupt and the read of the pin level require the clock to be validated. after a hardware reset, the pio clock is disabled by default. the user must configure the power management controller before any access to the input line information. 26.3.4 interrupt generation for interrupt handling, the pio controllers are considered as user peripherals. this means that the pio controller interrupt lines are connected among the interrupt sources 2 to 31. refer to the pio controller peripheral identifier in the produc t description to identify the interrupt sources dedicated to the pio controllers. the pio controller interrupt can be generated only if the pio controller clock is enabled.
208 6042e?atarm?14-dec-06 at91sam7a3 preliminary 26.4 functional description the pio controller features up to 32 fully-programmable i/o lines. most of the control logic asso- ciated to each i/o is represented in figure 26-3 . in this description each signal shown represents but one of up to 32 possible indexes. figure 26-3. i/o line control logic 1 0 1 0 1 0 glitch filter peripheral b input peripheral a input 1 0 pio_ifdr[0] pio_ifsr[0] pio_ifer[0] edge detector pio_pdsr[0] pio_isr[0] pio_idr[0] pio_imr[0] pio_ier[0] pio interrupt (up to 32 possible inputs) pio_isr[31] pio_idr[31] pio_imr[31] pio_ier[31] pad 1 0 pio_pudr[0] pio_pusr[0] pio_puer[0] pio_mddr[0] pio_mdsr[0] pio_mder[0] pio_codr[0] pio_odsr[0] pio_sodr[0] pio_pdr[0] pio_psr[0] pio_per[0] 1 0 1 0 pio_bsr[0] pio_absr[0] pio_asr[0] peripheral b output enable peripheral a output enable peripheral b output peripheral a output pio_odr[0] pio_osr[0] pio_oer[0]
209 6042e?atarm?14-dec-06 at91sam7a3 preliminary 26.4.1 pull-up resistor control each i/o line is designed with an embedded pull-up resistor. the pull-up resistor can be enabled or disabled by writing respectively pio_puer (pull-up enable register) and pio_pudr (pull- up disable resistor). writing in these registers re sults in setting or clearing the corresponding bit in pio_pusr (pull-up status register). readi ng a 1 in pio_pusr means the pull-up is dis- abled and reading a 0 means the pull-up is enabled. control of the pull-up resistor is possible regardless of the configuration of the i/o line. after reset, all of the pull-ups are enabled, i.e. pio_pusr resets at the value 0x0. 26.4.2 i/o line or peripheral function selection when a pin is multiplexed with one or two periph eral functions, the selection is controlled with the registers pio_per (pio enable register) and pio_pdr (pio disable register). the regis- ter pio_psr (pio status register) is the resu lt of the set and clear registers and indicates whether the pin is controlled by the corresponding peripheral or by the pio controller. a value of 0 indicates that the pin is controlled by the co rresponding on-chip peripheral selected in the pio_absr (ab select status regist er). a value of 1 indicates the pin is controlled by the pio controller. if a pin is used as a general purpose i/o line (not multiplexed with an on-chip peripheral), pio_per and pio_pdr have no effect and pio_psr returns 1 for the corresponding bit. after reset, most generally, the i/o lines are controlled by the pio controller, i.e. pio_psr resets at 1. however, in some events, it is important that pio lines are controlled by the periph- eral (as in the case of memory chip select lines that must be driven inactive after reset or for address lines that must be driven low for booting out of an external memory). thus, the reset value of pio_psr is defined at the product level, depending on the multiplexing of the device. 26.4.3 peripheral a or b selection the pio controller provides multiplexing of up to two peripheral functions on a single pin. the selection is performed by writing pio_asr (a select register) and pio_bsr (select b regis- ter). pio_absr (ab select status register) indicates which peripheral line is currently selected. for each pin, the corresponding bit at level 0 means peripheral a is selected whereas the corre- sponding bit at level 1 indicates that peripheral b is selected. note that multiplexing of peripheral lines a and b only affects the output line. the peripheral input lines are always connected to the pin input. after reset, pio_absr is 0, thus indicating that all the pio lines are configur ed on peripheral a. however, peripheral a generally does not drive the pin as the pio controller resets in i/o line mode. writing in pio_asr an d pio_bsr manages pio_absr regardless of th e configuration of the pin. however, assignment of a pin to a peripheral function requires a write in the corresponding peripheral selection register (pio_asr or pio_bsr) in addition to a write in pio_pdr. 26.4.4 output control when the i/0 line is assigned to a peripheral functi on, i.e. the corresponding bit in pio_psr is at 0, the drive of the i/o line is controlled by the peripheral. peripheral a or b, depending on the value in pio_absr, determines whet her the pin is driven or not.
210 6042e?atarm?14-dec-06 at91sam7a3 preliminary when the i/o line is controlled by the pio controller, the pin can be configured to be driven. this is done by writing pio_oer (output enable register) and pio_odr (output disable register). the results of these write operations are detected in pio_osr (output status register). when a bit in this register is at 0, the corresponding i/o line is used as an input only. when the bit is at 1, the corresponding i/o line is driven by the pio controller. the level driven on an i/o line can be determined by writing in pio_sodr (set output data register) and pio_codr (cle ar output data register). these write operations respectively set and clear pio_odsr (output data status register ), which represents the data driven on the i/o lines. writing in pio_oer and pio_odr manages pio_osr whether the pin is configured to be controlled by the pio controller or assigned to a peripheral function. this enables configura- tion of the i/o line prior to setting it to be managed by the pio controller. similarly, writing in pio_sodr and pio_codr effects pio_odsr. this is important as it defines the first level driven on the i/o line. 26.4.5 synchronous data output controlling all paralle l busses using several pios requires two successive write operations in the pio_sodr and pio_codr registers. this may lead to unexpected transient values. the pio controller offers a direct control of pio outputs by single write access to pio_odsr (output data status register). only bits unmasked by pio_oswsr (output write status register) are written. the mask bits in the pio_owsr are se t by writing to pio_ower (output write enable register) and cleared by writing to pio_owdr (output write disable register). after reset, the synchronous data output is disabled on all the i/o lines as pio_owsr resets at 0x0. 26.4.6 multi drive control (open drain) each i/o can be independently programmed in open drain by using the multi drive feature. this feature permits several drivers to be connected on the i/o line which is driven low only by each device. an external pull-up resistor (or enabling of the internal one) is generally required to guar- antee a high level on the line. the multi drive feature is controlled by pio_mder (multi-driver enable register) and pio_mddr (multi-driver disable register). the multi drive can be selected whether the i/o line is controlled by the pio controller or assigned to a peripheral function. pio_mdsr (multi-driver status register) indicates the pins that are configured to support external drivers. after reset, the multi drive feature is disabled on all pins, i.e. pio_mdsr resets at value 0x0. 26.4.7 output line timings figure 26-4 shows how the outputs are driven either by writing pio_sodr or pio_codr, or by directly writing pio_odsr. this last case is valid only if the corresponding bit in pio_owsr is set. figure 26-4 also shows when the feedback in pio_pdsr is available.
211 6042e?atarm?14-dec-06 at91sam7a3 preliminary figure 26-4. output line timings 26.4.8 inputs the level on each i/o line can be read through pio_pdsr (pin data status register). this reg- ister indicates the level of the i/o lines regardless of their configuration, whether uniquely as an input or driven by the pio controller or driven by a peripheral. reading the i/o line levels requires the clock of the pio controller to be enabled, otherwise pio_pdsr reads the levels present on the i/o line at the time the clock was disabled. 26.4.9 input glitch filtering optional input glitch filters are independently programmable on each i/o line. when the glitch fil- ter is enabled, a glitch with a duration of less than 1/2 master clock (mck) cycle is automatically rejected, while a pulse with a duration of 1 mast er clock cycle or more is accepted. for pulse durations between 1/2 master clock cycle and 1 master clock cycle the pulse may or may not be taken into account, depending on the precise timing of its occurrence. thus for a pulse to be visible it must exceed 1 master clock cycle, whereas for a glitch to be reliably filtered out, its duration must not exceed 1/2 master clock cycle. the filter introduces one master clock cycle latency if the pin level change occurs before a rising edge. however, this latency does not appear if the pin level chan ge occurs before a falling ed ge. this is illustrated in figure 26-5 . the glitch filters are controlled by the register set; pio_ifer (input filter enable register), pio_ifdr (input filter disable register) and pio_if sr (input filter status register). writing pio_ifer and pio_ifdr respectively sets and cl ears bits in pio_ifsr. this last register enables the glitch filt er on the i/o lines. when the glitch filter is enabled, it does not modify the behavior of the inputs on the peripherals. it acts only on the value read in pio_pdsr and on the input change interrupt detection. the glitch filters require that the pio controller clock is enabled. 2 cycles apb access 2 cycles apb access mck write pio_sodr write pio_odsr at 1 pio_odsr pio_pdsr write pio_codr write pio_odsr at 0
212 6042e?atarm?14-dec-06 at91sam7a3 preliminary figure 26-5. input glitch filter timing 26.4.10 input change interrupt the pio controller can be programmed to generate an interrupt when it detects an input change on an i/o line. the input change interrupt is cont rolled by writing pio_ier (interrupt enable register) and pio_idr (interrupt disable register), which respectively enable and disable the input change interrupt by setting and clearing the corresponding bit in pio_imr (interrupt mask register). as input change detection is possible only by comparing two successive samplings of the input of the i/o line, the pio controller clock must be enabled. the input change interrupt is available, regardless of the configuration of the i/o line, i.e. configured as an input only, con- trolled by the pio controller or assigned to a peripheral function. when an input change is detected on an i/o line, the corresponding bit in pio_isr (interrupt status register) is set. if the corresponding bit in pio_imr is set, the pio controller interrupt line is asserted. the interrupt signals of the thirty-two channels are ored-wired together to gen- erate a single interrupt signal to the advanced interrupt controller. when the software reads pio_isr, all the interrupts are automatically cleared. this signifies that all the interrupts that are pending when pio_isr is read must be handled. figure 26-6. input change interrupt timings mck pin level pio_pdsr if pio_ifsr = 0 pio_pdsr if pio_ifsr = 1 1 cycle 1 cycle 1 cycle up to 1.5 cycles 2 cycles up to 2.5 cycles up to 2 cycles 1 cycle 1 cycle mck pin level read pio_isr apb access pio_isr apb access
213 6042e?atarm?14-dec-06 at91sam7a3 preliminary 26.5 i/o lines programming example the programing example as shown in table 26-1 below is used to define the following configuration. 4-bit output port on i/o lines 0 to 3, (should be written in a single write operation), open-drain, with pull-up resistor four output signals on i/o lines 4 to 7 (to drive leds for example), driven high and low, no pull-up resistor four input signals on i/o lines 8 to 11 (to read push-button states for example), with pull-up resistors, glitch filters and input change interrupts four input signals on i/o line 12 to 15 to read an external device status (polled, thus no input change interrupt), no pull-up resistor, no glitch filter i/o lines 16 to 19 assigned to peripheral a functions with pull-up resistor i/o lines 20 to 23 assigned to peripheral b functions, no pull-up resistor i/o line 24 to 27 assigned to peripheral a with input change interrupt and pull-up resistor table 26-1. programming example register value to be written pio_per 0x0000 ffff pio_pdr 0x0fff 0000 pio_oer 0x0000 00ff pio_odr 0x0fff ff00 pio_ifer 0x0000 0f00 pio_ifdr 0x0fff f0ff pio_sodr 0x0000 0000 pio_codr 0x0fff ffff pio_ier 0x0f00 0f00 pio_idr 0x00ff f0ff pio_mder 0x0000 000f pio_mddr 0x0fff fff0 pio_pudr 0x00f0 00f0 pio_puer 0x0f0f ff0f pio_asr 0x0f0f 0000 pio_bsr 0x00f0 0000 pio_ower 0x0000 000f pio_owdr 0x0fff fff0
214 6042e?atarm?14-dec-06 at91sam7a3 preliminary 26.6 user interface each i/o line controlled by the pio controller is associated with a bit in each of the pio control- ler user interface registers. each register is 32 bits wide. if a parallel i/o line is not defined, writing to the corresponding bits has no effect. undefined bits read zero. if the i/o line is not mul- tiplexed with any peripheral, the i/o line is controlled by the pio controller and pio_psr returns 1 systematically. table 26-2. register mapping offset register name access reset value 0x0000 pio enable register pio_per write-only ? 0x0004 pio disable register pio_pdr write-only ? 0x0008 pio status register (1) pio_psr read-only 0x0000 0000 0x000c reserved 0x0010 output enable register pio_oer write-only ? 0x0014 output disable register pio_odr write-only ? 0x0018 output status regist er pio_osr read-only 0x0000 0000 0x001c reserved 0x0020 glitch input filter enab le register pio_ifer write-only ? 0x0024 glitch input filter disab le register pio_ifdr write-only ? 0x0028 glitch input filter status register pio_ifsr read-only 0x0000 0000 0x002c reserved 0x0030 set output data register pio_sodr write-only ? 0x0034 clear output data register pio_codr write-only ? 0x0038 output data status register (2) pio_odsr read-only 0x0000 0000 0x003c pin data status register (3) pio_pdsr read-only 0x0040 interrupt enable register pio_ier write-only ? 0x0044 interrupt disable register pio_idr write-only ? 0x0048 interrupt mask register pio_imr read-only 0x00000000 0x004c interrupt status register (4) pio_isr read-only 0x00000000 0x0050 multi-driver enable register pio_mder write-only ? 0x0054 multi-driver disable register pio_mddr write-only ? 0x0058 multi-driver status re gister pio_mdsr read-only 0x00000000 0x005c reserved 0x0060 pull-up disable register pio_pudr write-only ? 0x0064 pull-up enable register pio_puer write-only ? 0x0068 pad pull-up status regi ster pio_pusr read-only 0x00000000 0x006c reserved
215 6042e?atarm?14-dec-06 at91sam7a3 preliminary notes: 1. reset value of pio_psr depends on the product implementation. 2. pio_odsr is read-only or read/write depending on pio_owsr i/o lines. 3. reset value of pio_pdsr depends on the level of the i/o lines. 4. pio_isr is reset at 0x0. however, the first read of the r egister may read a different value as input changes may have occurred. 5. only this set of registers clears the status by writing 1 in the first register and sets the st atus by writing 1 in the secon d register. 0x0070 peripheral a select register (5) pio_asr write-only ? 0x0074 peripheral b select register (5) pio_bsr write-only ? 0x0078 ab status register (5) pio_absr read-only 0x00000000 0x007c to 0x009c reserved 0x00a0 output write enab le pio_ower write-only ? 0x00a4 output write disab le pio_owdr write-only ? 0x00a8 output write status re gister pio_owsr read-only 0x00000000 0x00ac reserved table 26-2. register mapping (continued) offset register name access reset value
216 6042e?atarm?14-dec-06 at91sam7a3 preliminary 26.6.1 pio controller pio enable register name: pio_per access type: write-only p0-p31: pio enable 0 = no effect. 1 = enables the pio to control the corresponding pin (disables peripheral control of the pin). 26.6.2 pio controller pio disable register name: pio_pdr access type: write-only p0-p31: pio disable 0 = no effect. 1 = disables the pio from controllin g the corresponding pin (enables peripheral contro l of the pin). 31 30 29 28 27 26 25 24 p31 p30 p29 p28 p27 p26 p25 p24 23 22 21 20 19 18 17 16 p23 p22 p21 p20 p19 p18 p17 p16 15 14 13 12 11 10 9 8 p15 p14 p13 p12 p11 p10 p9 p8 76543210 p7 p6 p5 p4 p3 p2 p1 p0 31 30 29 28 27 26 25 24 p31 p30 p29 p28 p27 p26 p25 p24 23 22 21 20 19 18 17 16 p23 p22 p21 p20 p19 p18 p17 p16 15 14 13 12 11 10 9 8 p15 p14 p13 p12 p11 p10 p9 p8 76543210 p7 p6 p5 p4 p3 p2 p1 p0
217 6042e?atarm?14-dec-06 at91sam7a3 preliminary 26.6.3 pio controller pio status register name: pio_psr access type: read-only p0-p31: pio status 0 = pio is inactive on the corresponding i/o line (peripheral is active). 1 = pio is active on the corresponding i/o line (peripheral is inactive). 26.6.4 pio controller output enable register name: pio_oer access type: write-only p0-p31: output enable 0 = no effect. 1 = enables the output on the i/o line. 31 30 29 28 27 26 25 24 p31 p30 p29 p28 p27 p26 p25 p24 23 22 21 20 19 18 17 16 p23 p22 p21 p20 p19 p18 p17 p16 15 14 13 12 11 10 9 8 p15 p14 p13 p12 p11 p10 p9 p8 76543210 p7 p6 p5 p4 p3 p2 p1 p0 31 30 29 28 27 26 25 24 p31 p30 p29 p28 p27 p26 p25 p24 23 22 21 20 19 18 17 16 p23 p22 p21 p20 p19 p18 p17 p16 15 14 13 12 11 10 9 8 p15 p14 p13 p12 p11 p10 p9 p8 76543210 p7 p6 p5 p4 p3 p2 p1 p0
218 6042e?atarm?14-dec-06 at91sam7a3 preliminary 26.6.5 pio controller output disable register name: pio_odr access type: write-only p0-p31: output disable 0 = no effect. 1 = disables the output on the i/o line. 26.6.6 pio controller output status register name: pio_osr access type: read-only p0-p31: output status 0 = the i/o line is a pure input. 1 = the i/o line is enabled in output. 31 30 29 28 27 26 25 24 p31 p30 p29 p28 p27 p26 p25 p24 23 22 21 20 19 18 17 16 p23 p22 p21 p20 p19 p18 p17 p16 15 14 13 12 11 10 9 8 p15 p14 p13 p12 p11 p10 p9 p8 76543210 p7 p6 p5 p4 p3 p2 p1 p0 31 30 29 28 27 26 25 24 p31 p30 p29 p28 p27 p26 p25 p24 23 22 21 20 19 18 17 16 p23 p22 p21 p20 p19 p18 p17 p16 15 14 13 12 11 10 9 8 p15 p14 p13 p12 p11 p10 p9 p8 76543210 p7 p6 p5 p4 p3 p2 p1 p0
219 6042e?atarm?14-dec-06 at91sam7a3 preliminary 26.6.7 pio controller input filter enable register name: pio_ifer access type: write-only p0-p31: input filter enable 0 = no effect. 1 = enables the input glitch filter on the i/o line. 26.6.8 pio controller input filter disable register name: pio_ifdr access type: write-only p0-p31: input filter disable 0 = no effect. 1 = disables the input glitch filter on the i/o line. 31 30 29 28 27 26 25 24 p31 p30 p29 p28 p27 p26 p25 p24 23 22 21 20 19 18 17 16 p23 p22 p21 p20 p19 p18 p17 p16 15 14 13 12 11 10 9 8 p15 p14 p13 p12 p11 p10 p9 p8 76543210 p7 p6 p5 p4 p3 p2 p1 p0 31 30 29 28 27 26 25 24 p31 p30 p29 p28 p27 p26 p25 p24 23 22 21 20 19 18 17 16 p23 p22 p21 p20 p19 p18 p17 p16 15 14 13 12 11 10 9 8 p15 p14 p13 p12 p11 p10 p9 p8 76543210 p7 p6 p5 p4 p3 p2 p1 p0
220 6042e?atarm?14-dec-06 at91sam7a3 preliminary 26.6.9 pio controller input filter status register name: pio_ifsr access type: read-only p0-p31: input filer status 0 = the input glitch filter is disabled on the i/o line. 1 = the input glitch filter is enabled on the i/o line. 26.6.10 pio controller set output data register name: pio_sodr access type: write-only p0-p31: set output data 0 = no effect. 1 = sets the data to be driven on the i/o line. 31 30 29 28 27 26 25 24 p31 p30 p29 p28 p27 p26 p25 p24 23 22 21 20 19 18 17 16 p23 p22 p21 p20 p19 p18 p17 p16 15 14 13 12 11 10 9 8 p15 p14 p13 p12 p11 p10 p9 p8 76543210 p7 p6 p5 p4 p3 p2 p1 p0 31 30 29 28 27 26 25 24 p31 p30 p29 p28 p27 p26 p25 p24 23 22 21 20 19 18 17 16 p23 p22 p21 p20 p19 p18 p17 p16 15 14 13 12 11 10 9 8 p15 p14 p13 p12 p11 p10 p9 p8 76543210 p7 p6 p5 p4 p3 p2 p1 p0
221 6042e?atarm?14-dec-06 at91sam7a3 preliminary 26.6.11 pio controller clear output data register name: pio_codr access type: write-only p0-p31: set output data 0 = no effect. 1 = clears the data to be driven on the i/o line. 26.6.12 pio controller output data status register name: pio_odsr access type: read-only or read/write p0-p31: output data status 0 = the data to be driven on the i/o line is 0. 1 = the data to be driven on the i/o line is 1. 31 30 29 28 27 26 25 24 p31 p30 p29 p28 p27 p26 p25 p24 23 22 21 20 19 18 17 16 p23 p22 p21 p20 p19 p18 p17 p16 15 14 13 12 11 10 9 8 p15 p14 p13 p12 p11 p10 p9 p8 76543210 p7 p6 p5 p4 p3 p2 p1 p0 31 30 29 28 27 26 25 24 p31 p30 p29 p28 p27 p26 p25 p24 23 22 21 20 19 18 17 16 p23 p22 p21 p20 p19 p18 p17 p16 15 14 13 12 11 10 9 8 p15 p14 p13 p12 p11 p10 p9 p8 76543210 p7 p6 p5 p4 p3 p2 p1 p0
222 6042e?atarm?14-dec-06 at91sam7a3 preliminary 26.6.13 pio controller pin data status register name: pio_pdsr access type: read-only p0-p31: output data status 0 = the i/o line is at level 0. 1 = the i/o line is at level 1. 26.6.14 pio controller interrupt enable register name: pio_ier access type: write-only p0-p31: input change interrupt enable 0 = no effect. 1 = enables the input change interrupt on the i/o line. 31 30 29 28 27 26 25 24 p31 p30 p29 p28 p27 p26 p25 p24 23 22 21 20 19 18 17 16 p23 p22 p21 p20 p19 p18 p17 p16 15 14 13 12 11 10 9 8 p15 p14 p13 p12 p11 p10 p9 p8 76543210 p7 p6 p5 p4 p3 p2 p1 p0 31 30 29 28 27 26 25 24 p31 p30 p29 p28 p27 p26 p25 p24 23 22 21 20 19 18 17 16 p23 p22 p21 p20 p19 p18 p17 p16 15 14 13 12 11 10 9 8 p15 p14 p13 p12 p11 p10 p9 p8 76543210 p7 p6 p5 p4 p3 p2 p1 p0
223 6042e?atarm?14-dec-06 at91sam7a3 preliminary 26.6.15 pio controller interrupt disable register name: pio_idr access type: write-only p0-p31: input change interrupt disable 0 = no effect. 1 = disables the input change interrupt on the i/o line. 26.6.16 pio controller interrupt mask register name: pio_imr access type: read-only p0-p31: input change interrupt mask 0 = input change interrupt is disabled on the i/o line. 1 = input change interrupt is enabled on the i/o line. 31 30 29 28 27 26 25 24 p31 p30 p29 p28 p27 p26 p25 p24 23 22 21 20 19 18 17 16 p23 p22 p21 p20 p19 p18 p17 p16 15 14 13 12 11 10 9 8 p15 p14 p13 p12 p11 p10 p9 p8 76543210 p7 p6 p5 p4 p3 p2 p1 p0 31 30 29 28 27 26 25 24 p31 p30 p29 p28 p27 p26 p25 p24 23 22 21 20 19 18 17 16 p23 p22 p21 p20 p19 p18 p17 p16 15 14 13 12 11 10 9 8 p15 p14 p13 p12 p11 p10 p9 p8 76543210 p7 p6 p5 p4 p3 p2 p1 p0
224 6042e?atarm?14-dec-06 at91sam7a3 preliminary 26.6.17 pio controller interrupt status register name: pio_isr access type: read-only p0-p31: input change interrupt status 0 = no input change has been detected on the i/o line since pio_isr was last read or since reset. 1 = at least one input change has been detected on the i/o line since pio_isr was last read or since reset. 26.6.18 pio multi-driver enable register name: pio_mder access type: write-only p0-p31: multi drive enable. 0 = no effect. 1 = enables multi drive on the i/o line. 31 30 29 28 27 26 25 24 p31 p30 p29 p28 p27 p26 p25 p24 23 22 21 20 19 18 17 16 p23 p22 p21 p20 p19 p18 p17 p16 15 14 13 12 11 10 9 8 p15 p14 p13 p12 p11 p10 p9 p8 76543210 p7 p6 p5 p4 p3 p2 p1 p0 31 30 29 28 27 26 25 24 p31 p30 p29 p28 p27 p26 p25 p24 23 22 21 20 19 18 17 16 p23 p22 p21 p20 p19 p18 p17 p16 15 14 13 12 11 10 9 8 p15 p14 p13 p12 p11 p10 p9 p8 76543210 p7 p6 p5 p4 p3 p2 p1 p0
225 6042e?atarm?14-dec-06 at91sam7a3 preliminary 26.6.19 pio multi-driver disable register name: pio_mddr access type: write-only p0-p31: multi drive disable. 0 = no effect. 1 = disables multi drive on the i/o line. 26.6.20 pio multi-driver status register name: pio_mdsr access type: read-only p0-p31: multi drive status. 0 = the multi drive is disabled on the i/o line. the pin is driven at high and low level. 1 = the multi drive is enabled on the i/o lin e. the pin is driven at low level only. 31 30 29 28 27 26 25 24 p31 p30 p29 p28 p27 p26 p25 p24 23 22 21 20 19 18 17 16 p23 p22 p21 p20 p19 p18 p17 p16 15 14 13 12 11 10 9 8 p15 p14 p13 p12 p11 p10 p9 p8 76543210 p7 p6 p5 p4 p3 p2 p1 p0 31 30 29 28 27 26 25 24 p31 p30 p29 p28 p27 p26 p25 p24 23 22 21 20 19 18 17 16 p23 p22 p21 p20 p19 p18 p17 p16 15 14 13 12 11 10 9 8 p15 p14 p13 p12 p11 p10 p9 p8 76543210 p7 p6 p5 p4 p3 p2 p1 p0
226 6042e?atarm?14-dec-06 at91sam7a3 preliminary 26.6.21 pio pull up disable register name: pio_pudr access type: write-only p0-p31: pull up disable. 0 = no effect. 1 = disables the pull up resistor on the i/o line. 26.6.22 pio pull up enable register name: pio_puer access type: write-only p0-p31: pull up enable. 0 = no effect. 1 = enables the pull up resistor on the i/o line. 31 30 29 28 27 26 25 24 p31 p30 p29 p28 p27 p26 p25 p24 23 22 21 20 19 18 17 16 p23 p22 p21 p20 p19 p18 p17 p16 15 14 13 12 11 10 9 8 p15 p14 p13 p12 p11 p10 p9 p8 76543210 p7 p6 p5 p4 p3 p2 p1 p0 31 30 29 28 27 26 25 24 p31 p30 p29 p28 p27 p26 p25 p24 23 22 21 20 19 18 17 16 p23 p22 p21 p20 p19 p18 p17 p16 15 14 13 12 11 10 9 8 p15 p14 p13 p12 p11 p10 p9 p8 76543210 p7 p6 p5 p4 p3 p2 p1 p0
227 6042e?atarm?14-dec-06 at91sam7a3 preliminary 26.6.23 pio pull up status register name: pio_pusr access type: read-only p0-p31: pull up status. 0 = pull up resistor is enabled on the i/o line. 1 = pull up resistor is disabled on the i/o line. 26.6.24 pio peripheral a select register name: pio_asr access type: write-only p0-p31: peripheral a select. 0 = no effect. 1 = assigns the i/o line to the peripheral a function. 31 30 29 28 27 26 25 24 p31 p30 p29 p28 p27 p26 p25 p24 23 22 21 20 19 18 17 16 p23 p22 p21 p20 p19 p18 p17 p16 15 14 13 12 11 10 9 8 p15 p14 p13 p12 p11 p10 p9 p8 76543210 p7 p6 p5 p4 p3 p2 p1 p0 31 30 29 28 27 26 25 24 p31 p30 p29 p28 p27 p26 p25 p24 23 22 21 20 19 18 17 16 p23 p22 p21 p20 p19 p18 p17 p16 15 14 13 12 11 10 9 8 p15 p14 p13 p12 p11 p10 p9 p8 76543210 p7 p6 p5 p4 p3 p2 p1 p0
228 6042e?atarm?14-dec-06 at91sam7a3 preliminary 26.6.25 pio peripheral b select register name: pio_bsr access type: write-only p0-p31: peripheral b select. 0 = no effect. 1 = assigns the i/o line to the peripheral b function. 26.6.26 pio peripheral a b status register name: pio_absr access type: read-only p0-p31: peripheral a b status. 0 = the i/o line is assigned to the peripheral a. 1 = the i/o line is assigned to the peripheral b. 31 30 29 28 27 26 25 24 p31 p30 p29 p28 p27 p26 p25 p24 23 22 21 20 19 18 17 16 p23 p22 p21 p20 p19 p18 p17 p16 15 14 13 12 11 10 9 8 p15 p14 p13 p12 p11 p10 p9 p8 76543210 p7 p6 p5 p4 p3 p2 p1 p0 31 30 29 28 27 26 25 24 p31 p30 p29 p28 p27 p26 p25 p24 23 22 21 20 19 18 17 16 p23 p22 p21 p20 p19 p18 p17 p16 15 14 13 12 11 10 9 8 p15 p14 p13 p12 p11 p10 p9 p8 76543210 p7 p6 p5 p4 p3 p2 p1 p0
229 6042e?atarm?14-dec-06 at91sam7a3 preliminary 26.6.27 pio output write enable register name: pio_ower access type: write-only p0-p31: output write enable. 0 = no effect. 1 = enables writing pio_odsr for the i/o line. 26.6.28 pio output write disable register name: pio_owdr access type: write-only p0-p31: output write disable. 0 = no effect. 1 = disables writing pio_odsr for the i/o line. 31 30 29 28 27 26 25 24 p31 p30 p29 p28 p27 p26 p25 p24 23 22 21 20 19 18 17 16 p23 p22 p21 p20 p19 p18 p17 p16 15 14 13 12 11 10 9 8 p15 p14 p13 p12 p11 p10 p9 p8 76543210 p7 p6 p5 p4 p3 p2 p1 p0 31 30 29 28 27 26 25 24 p31 p30 p29 p28 p27 p26 p25 p24 23 22 21 20 19 18 17 16 p23 p22 p21 p20 p19 p18 p17 p16 15 14 13 12 11 10 9 8 p15 p14 p13 p12 p11 p10 p9 p8 76543210 p7 p6 p5 p4 p3 p2 p1 p0
230 6042e?atarm?14-dec-06 at91sam7a3 preliminary 26.6.29 pio output write status register name: pio_owsr access type: read-only p0-p31: output write status. 0 = writing pio_odsr does not affect the i/o line. 1 = writing pio_odsr affects the i/o line. 31 30 29 28 27 26 25 24 p31 p30 p29 p28 p27 p26 p25 p24 23 22 21 20 19 18 17 16 p23 p22 p21 p20 p19 p18 p17 p16 15 14 13 12 11 10 9 8 p15 p14 p13 p12 p11 p10 p9 p8 76543210 p7 p6 p5 p4 p3 p2 p1 p0
231 6042e?atarm?14-dec-06 at91sam7a3 preliminary 27. serial peripheral interface (spi) 27.1 overview the serial peripheral interface (spi) circuit is a synchronous serial data link that provides com- munication with external devices in master or slave mode. it also enables communication between processors if an external processor is connected to the system. the serial peripheral interface is essentially a shift register that serially transmits data bits to other spis. during a data transfer, one spi system acts as the ?master?' which controls the data flow, while the other devices act as ?slaves'' whic h have data shifted into and out by the master. different cpus can take turn being masters (multiple master protocol opposite to single master protocol where one cpu is always the master while all of the others are always slaves) and one master may simultaneously shift da ta into multiple slaves. howeve r, only one slave may drive its output to write data back to the master at any given time. a slave device is selected when the master asse rts its nss signal. if multiple slave devices exist, the master generates a separate slav e select signal for each slave (npcs). the spi system consists of two data lines and two control lines: master out slave in (mosi): this data line supplies the output data from the master shifted into the input(s) of the slave(s). master in slave out (miso): this data line supplies the output data from a slave to the input of the master. there may be no more than one slave transmitting data during any particular transfer. serial clock (spck): this control line is driven by the master and regulates the flow of the data bits. the master may transmit data at a variety of baud rates; the spck line cycles once for each bit that is transmitted. slave select (nss): this control line allows slaves to be turned on and off by hardware.
232 6042e?atarm?14-dec-06 at91sam7a3 preliminary 27.2 block diagram figure 27-1. block diagram spi interface interrupt control pio pdc pmc mck spi interrupt spck miso mosi npcs0/nss npcs1 npcs2 npcs3 apb
233 6042e?atarm?14-dec-06 at91sam7a3 preliminary 27.3 application block diagram figure 27-2. application block diagram: single master/multiple slave implementation spi master spck miso mosi npcs0 npcs1 npcs2 spck miso mosi nss slave 0 spck miso mosi nss slave 1 spck miso mosi nss slave 2 nc npcs3
234 6042e?atarm?14-dec-06 at91sam7a3 preliminary 27.4 signal description 27.5 product dependencies 27.5.1 i/o lines the pins used for interfacing the compliant ex ternal devices may be multiplexed with pio lines. the programmer must first program the pio controllers to assign the spi pins to their peripheral functions. 27.5.2 power management the spi may be clocked through the power management controller (pmc), thus the program- mer must first configure the pmc to enable the spi clock. 27.5.3 interrupt the spi interface has an interrupt line connected to the advanced interrupt controller (aic). handling the spi interrupt requires programming the aic before configuring the spi. table 27-1. signal description pin name pin description type master slave miso master in slave out input output mosi master out slave in output input spck serial clock output input npcs1-npcs3 peripheral chip selects output unused npcs0/nss peripheral chip select/slave select output input
235 6042e?atarm?14-dec-06 at91sam7a3 preliminary 27.6 functional description 27.6.1 modes of operation the spi operates in master mode or in slave mode. operation in master mode is programmed by writing at 1 the mstr bit in the mode register. the pins npcs0 to npcs3 are all configured as outputs, the spck pin is driven, the miso line is wired on the receiver input and the mosi line driven as an output by the transmitter. if the mstr bit is written at 0, the spi operates in slave mode. the miso line is driven by the transmitter output, the mosi line is wired on the re ceiver input, the spck pin is driven by the transmitter to synchronize the receiver. the npcs0 pin becomes an input, and is used as a slave select signal (nss). the pins npcs1 to npcs3 are not driven and can be used for other purposes. the data transfers are identically programmable for both modes of operations. the baud rate generator is activated only in master mode. 27.6.2 data transfer four combinations of polarity and phase are available for data transfers. the clock polarity is programmed with the cpol bit in the chip select register. the clock phase is programmed with the ncpha bit. these two parameters determine th e edges of the clock signal on which data is driven and sampled. each of the two parameters has two possible states, resulting in four possi- ble combinations that are incompatible with one another. thus, a master/slave pair must use the same parameter pair values to communicate. if multiple slaves are used and fixed in different configurations, the master must reconfigure itself each time it needs to communicate with a dif- ferent slave. table 27-2 shows the four modes and corresponding parameter settings. figure 27-3 and figure 27-4 show examples of data transfers. table 27-2. spi bus protocol mode spi mode cpol ncpha 001 100 211 310
236 6042e?atarm?14-dec-06 at91sam7a3 preliminary figure 27-3. spi transfer format (ncpha = 1, 8 bits per transfer) figure 27-4. spi transfer format (ncpha = 0, 8 bits per transfer) 6 * spck (cpol = 0) spck (cpol = 1) mosi (from master) miso (from slave) nss (to slave) spck cycle (for reference) msb msb lsb lsb 6 6 5 5 4 4 3 3 2 2 1 1 * not defined, but normally msb of previous character received. 1 2345 78 6 * spck (cpol = 0) spck (cpol = 1) 1 2345 7 mosi (from master) miso (from slave) nss (to slave) spck cycle (for reference) 8 msb msb lsb lsb 6 6 5 5 4 4 3 3 1 1 * not defined but normally lsb of previous character transmitted. 2 2 6
237 6042e?atarm?14-dec-06 at91sam7a3 preliminary 27.6.3 master mode operations when configured in master mode, the spi operates on the clock generated by the internal pro- grammable baud rate generator. it fully controls the data transfers to and from the slave(s) connected to the spi bus. the spi drives the chip select line to the slave and the serial clock signal (spck). the spi features two holding registers, the transmit data register and the receive data regis- ter, and a single shift register. the holding registers maintain the data flow at a constant rate. after enabling the spi, a data transfer begins when the processor writes to the spi_tdr (trans- mit data register). the written data is immediat ely transferred in the shift register and transfer on the spi bus starts. while the data in the shift register is shifted on the mosi line, the miso line is sampled and shifted in the shift register. transmission cannot occur without reception. before writing the tdr, the pcs field must be set in order to select a slave. if new data is written in spi_tdr during the transfe r, it stays in it until the current transfer is completed. then, the received data is transferred from the shift register to spi_rdr, the data in spi_tdr is loaded in the shift register and a new transfer starts. the transfer of a data written in spi_tdr in t he shift register is indicated by the tdre bit (transmit data register empty) in the status register (spi_sr). when new data is written in spi_tdr, this bit is cleared. the tdre bit is used to trigger the transmit pdc channel. the end of transfer is indicated by the txempty flag in the spi_sr register. if a transfer delay (dlybct) is greater than 0 for the last transfer, txempty is set after the completion of said delay. the master clock (mck) can be switched off at this time. the transfer of received data from the shift register in spi_rdr is indicated by the rdrf bit (receive data register full) in the status register (spi_sr). when the received data is read, the rdrf bit is cleared. if the spi_rdr (receive data register) has not been read before new data is received, the overrun error bit (ovres) in spi_sr is set. as long as this flag is set, data is loaded in spi_rdr. the user has to read the status register to clear the ovres bit. figure 27-5 on page 238 shows a block diagram of the spi when operating in master mode. fig- ure 27-6 on page 239 shows a flow chart describing how transfers are handled.
238 6042e?atarm?14-dec-06 at91sam7a3 preliminary 27.6.3.1 master mode block diagram figure 27-5. master mode block diagram shift register spck mosi lsb msb miso spi_rdr rd spi clock tdre spi_tdr td rdrf ovres spi_csr0..3 cpol ncpha bits mck baud rate generator spi_csr0..3 scbr npcs3 npcs0 npcs2 npcs1 npcs0 0 1 ps spi_mr pcs spi_tdr pcs modf current peripheral spi_rdr pcs spi_csr0..3 csaat pcsdec modfdis mstr
239 6042e?atarm?14-dec-06 at91sam7a3 preliminary 27.6.3.2 master mode flow diagram figure 27-6. master mode flow diagram spi enable csaat ? ps ? 1 0 0 1 1 npcs = spi_tdr(pcs) npcs = spi_mr(pcs) delay dlybs serializer = spi_tdr(td) tdre = 1 data transfer spi_rdr(rd) = serializer rdrf = 1 tdre ? npcs = 0xf delay dlybcs fixed peripheral variable peripheral delay dlybct 0 1 csaat ? 0 tdre ? 1 0 ps ? 0 1 spi_tdr(pcs) = npcs ? no yes spi_mr(pcs) = npcs ? no npcs = 0xf delay dlybcs npcs = spi_tdr(pcs) npcs = 0xf delay dlybcs npcs = spi_mr(pcs), spi_tdr(pcs) fixed peripheral variable peripheral - npcs defines the current chip select - csaat, dlybs, dlybct refer to the fields of the chip select register corresponding to the current chip select - when npcs is 0xf, csaat is 0.
240 6042e?atarm?14-dec-06 at91sam7a3 preliminary 27.6.3.3 clock generation the spi baud rate clock is generated by dividing the master clock (mck), by a value between 1 and 255. this allows a maximum operating baud rate at up to master clock and a minimum operating baud rate of mck divided by 255. programming the scbr field at 0 is forbidden. tri ggering a transfer while scbr is at 0 can lead to unpredictable results. at reset, scbr is 0 and the user has to program it at a valid value before performing the first transfer. the divisor can be defined independently for each chip select, as it has to be programmed in the scbr field of the chip select registers. this allows the spi to automatically adapt the baud rate for each interfaced peripheral without reprogramming. 27.6.3.4 transfer delays figure 27-7 shows a chip select transfer change and consecutive transfers on the same chip select. three delays can be programmed to modify the transfer waveforms: the delay between chip selects, programmable only once for all the ch ip selects by writing the dlybcs field in the mode register. allows insertion of a delay between release of one chip select and before assertion of a new one. the delay before spck, independently programmable for each chip select by writing the field dlybs. allows the start of spck to be delayed after the chip select has been asserted. the delay between consecutive transfers, independently programmable for each chip select by writing the dlybct field. allows insertion of a delay between two transfers occurring on the same chip select these delays allow the spi to be adapted to the interfaced peripherals and their speed and bus release time. figure 27-7. programmable delays 27.6.3.5 peripheral selection the serial peripherals are selected through the as sertion of the npcs0 to npcs3 signals. by default, all the npcs signals are high before and after each transfer. the peripheral selection can be performed in two different ways: dlybcs dlybs dlybct dlybct chip select 1 chip select 2 spck
241 6042e?atarm?14-dec-06 at91sam7a3 preliminary fixed peripheral select: spi exchanges data with only one peripheral variable peripheral select: data can be exchanged with more than one peripheral fixed peripheral select is activated by writing the ps bit to zero in spi_mr (mode register). in this case, the current peripheral is defined by the pcs field in spi_mr and the pcs field in the spi_tdr has no effect. variable peripheral select is ac tivated by setting ps bit to one. the pcs field in spi_tdr is used to select the current peripheral. this means that the peripheral selection can be defined for each new data. the fixed peripheral selection allows buffer transfers with a single peripheral. using the pdc is an optimal means, as the size of the data transfer between the memory and the spi is either 8 bits or 16 bits. however, changing the peripheral selection requires the mode register to be reprogrammed. the variable peripheral selection allows buffer transfers with multiple peripherals without repro- gramming the mode register. data written in spi_tdr is 32 bits wide and defines the real data to be transmitted and the peripheral it is desti ned to. using the pdc in th is mode requires 32-bit wide buffers, with the data in the lsbs and the pcs and lastxfer fields in the msbs, how- ever the spi still controls the number of bits (8 to16) to be transferred through miso and mosi lines with the chip select configuration registers. this is not the optimal means in term of mem- ory size for the buffers, but it provides a very effective means to exchange data with several peripherals without any intervention of the processor. 27.6.3.6 peripheral chip select decoding the user can program the spi to operate with up to 15 peripherals by decoding the four chip select lines, npcs0 to npcs3 with an external l ogic. this can be enabled by writing the pcs- dec bit at 1 in the mode register (spi_mr). when operating without decoding, the spi makes sure that in any case only one chip select line is activated, i.e. driven low at a time. if two bits are defined low in a pcs field, only the lowest numbered chip select is driven low. when operating with decoding, the spi directly outputs the value defined by the pcs field of either the mode register or the transmit data register (depending on ps). as the spi sets a default value of 0xf on the chip select lines (i.e. all chip select lines at 1) when not processing any transfer, only 15 peripherals can be decoded. the spi has only four chip select registers, not 15. as a result, when decoding is activated, each chip select defines the characteristics of up to four peripherals. as an example, spi_crs0 defines the characteristics of the externally decoded peripherals 0 to 3, corresponding to the pcs values 0x0 to 0x3. thus, the user has to make sure to connect compatible peripherals on the decoded chip select lines 0 to 3, 4 to 7, 8 to 11 and 12 to 14. 27.6.3.7 peripheral deselection when operating normally, as soon as the transfer of the last data written in spi_tdr is com- pleted, the npcs lines all rise. this might lead to runtime error if the processor is too long in responding to an interrupt, and thus might lead to difficulties for interfacing with some serial peripherals requiring the chip select line to remain active during a full set of transfers.
242 6042e?atarm?14-dec-06 at91sam7a3 preliminary to facilitate interfacing with such devices, the chip select regist er can be prog rammed with the csaat bit (chip select active after transfer) at 1. this allows the chip select lines to remain in their current state (low = active) until transfer to another peripheral is required. figure 27-8 shows different peripheral deselection cases and the effect of the csaat bit. figure 27-8. peripheral deselection 27.6.3.8 mode fault detection a mode fault is detected when the spi is programmed in master mode and a low level is driven by an external master on the npcs0/nss sign al. npcs0, mosi, miso and spck must be con- figured in open drain through the pio controller, so that external pull up resistors are needed to guarantee high level. when a mode fault is detected, the modf bit in the spi_sr is set until the spi_sr is read and the spi is automatically disabl ed until re-enabled by writing t he spien bit in the spi_cr (con- trol register) at 1. by default, the mode fault detection circuitr y is enabled. the user can disable mode fault detection by setting the modfdis bit in the spi mode register (spi_mr). a npcs[0..3] write spi_tdr tdre npcs[0..3] write spi_tdr tdre npcs[0..3] write spi_tdr tdre dlybcs pcs = a dlybcs dlybct a pcs = b b dlybcs pcs = a dlybcs dlybct a pcs = b b dlybcs dlybct pcs=a a dlybcs dlybct a pcs = a a a dlybct aa csaat = 0 dlybct aa csaat = 1 a
243 6042e?atarm?14-dec-06 at91sam7a3 preliminary 27.6.4 spi slave mode when operating in slave mode, the spi processes data bits on the clock provided on the spi clock pin (spck). the spi waits for nss to go active before receiving the serial clock from an external master. when nss falls, the clock is validated on the serializer, which processes the number of bits defined by the bits field of the chip select register 0 (spi_csr0). these bits are processed following a phase and a polarity defined respectively by the ncpha and cpol bits of the spi_csr0. note that bits, cpol and ncpha of the other chip select registers have no effect when the spi is programmed in slave mode. the bits are shifted out on the miso line and sampled on the mosi line. when all the bits are processed, the received data is transferred in the receive data register and the rdrf bit rises. if rdrf is already high wh en the data is transf erred, the overrun bit rises and the data transfer to spi_rdr is aborted. when a transfer starts, the data shifted out is the data present in the shift register. if no data has been written in the transmit data register (spi_tdr), the la st data received is transferred. if no data has been received since the last reset, all bits are transmitted low, as the shift regis- ter resets at 0. when a first data is written in sp i_tdr, it is transferred immediat ely in the shift register and the tdre bit rises. if new data is wri tten, it remains in spi_tdr until a transfer occurs, i.e. nss falls and there is a valid clock on the spck pin. w hen the transfer occurs, the last data written in spi_tdr is transferred in the shift register and the tdre bit rises. this enables frequent updates of critical variables with single transfers. then, a new data is loaded in the shift register from the transmit data register. in case no character is ready to be transmitted, i.e. no character has been written in spi_tdr since the last load from spi_tdr to the shift register, the shift register is not modified and the last received character is retransmitted. figure 27-9 shows a block diagram of the spi when operating in slave mode. figure 27-9. slave mode functional block diagram shift register spck spiens lsb msb nss mosi spi_rdr rd spi clock tdre spi_tdr td rdrf ovres spi_csr0 cpol ncpha bits spien spidis miso
244 6042e?atarm?14-dec-06 at91sam7a3 preliminary 27.7 serial peripheral inte rface (spi) user interface table 27-3. spi register mapping offset register register name access reset 0x00 control register spi_cr write-only --- 0x04 mode register spi_mr read/write 0x0 0x08 receive data register spi_rdr read-only 0x0 0x0c transmit data register spi_tdr write-only --- 0x10 status register spi_sr read-only 0x000000f0 0x14 interrupt enable register spi_ier write-only --- 0x18 interrupt disable register spi_idr write-only --- 0x1c interrupt mask register spi_imr read-only 0x0 0x20 - 0x2c reserved 0x30 chip select register 0 spi_csr0 read/write 0x0 0x34 chip select register 1 spi_csr1 read/write 0x0 0x38 chip select register 2 spi_csr2 read/write 0x0 0x3c chip select register 3 spi_csr3 read/write 0x0 0x004c - 0x00f8 reserved ? ? ? 0x004c - 0x00fc reserved ? ? ? 0x100 - 0x124 reserved for the pdc
245 6042e?atarm?14-dec-06 at91sam7a3 preliminary 27.7.1 spi control register name: spi_cr access type: write-only spien: spi enable 0 = no effect. 1 = enables the spi to transfer and receive data. spidis: spi disable 0 = no effect. 1 = disables the spi. as soon as spidis is set, spi finishes its transfer. all pins are set in input mode and no data is received or transmitted. if a transfer is in progress, the transfer is finished before the spi is disabled. if both spien and spidis are equal to one when the control register is written, the spi is disabled. swrst: spi software reset 0 = no effect. 1 = reset the spi. a software-triggered hardware reset of the spi interface is performed. the spi is in slave mode after software reset. pdc channels are not affected by software reset. lastxfer: last transfer 0 = no effect. 1 = the current npcs will be deasserted afte r the character written in td has been tr ansferred. when c saat is set, this allows to close the communication with the current serial periph eral by raising the correspondi ng npcs line as soon as td transfer has completed. 31 30 29 28 27 26 25 24 ???????lastxfer 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ???????? 76543210 swrst?????spidisspien
246 6042e?atarm?14-dec-06 at91sam7a3 preliminary 27.7.2 spi mode register name: spi_mr access type: read/write mstr: master/slave mode 0 = spi is in slave mode. 1 = spi is in master mode. ps: peripheral select 0 = fixed peripheral select. 1 = variable peripheral select. pcsdec: chip select decode 0 = the chip selects are directly connected to a peripheral device. 1 = the four chip select lines are connected to a 4- to 16-bit decoder. when pcsdec equals one, up to 15 chip select signals can be generated with the four lines using an external 4- to 16-bit decoder. the chip select registers define the characteristics of the 15 chip selects according to the following rules: spi_csr0 defines peripheral chip select signals 0 to 3. spi_csr1 defines peripheral chip select signals 4 to 7. spi_csr2 defines peripheral chip select signals 8 to 11. spi_csr3 defines peripheral chip select signals 12 to 14. modfdis: mode fault detection 0 = mode fault detection is enabled. 1 = mode fault detection is disabled. llb: local loopback enable 0 = local loopback path disabled. 1 = local loopback path enabled. llb controls the local loopback on the data serializer for te sting in master mode only. (miso is internally connected on mosi.) 31 30 29 28 27 26 25 24 dlybcs 23 22 21 20 19 18 17 16 ???? pcs 15 14 13 12 11 10 9 8 ???????? 76543210 llb ? ? modfdis pcsdec ps mstr
247 6042e?atarm?14-dec-06 at91sam7a3 preliminary pcs: peripheral chip select this field is only used if fixed peripheral select is active (ps = 0). if pcsdec = 0: pcs = xxx0 npcs[3:0] = 1110 pcs = xx01 npcs[3:0] = 1101 pcs = x011 npcs[3:0] = 1011 pcs = 0111 npcs[3:0] = 0111 pcs = 1111 forbidden (no peripheral is selected) (x = don?t care) if pcsdec = 1: npcs[3:0] output signals = pcs. dlybcs: delay between chip selects this field defines the delay from npcs inactive to the ac tivation of another npcs. the dlybcs time guarantees non-over- lapping chip selects and solves bus contentions in case of peripherals having long data float times. if dlybcs is less than or eq ual to six, six mck periods will be inserted by default. otherwise, the following equat ion determines the delay: delay between chip selects dlybcs mck ---------------------- - =
248 6042e?atarm?14-dec-06 at91sam7a3 preliminary 27.7.3 spi receive data register name: spi_rdr access type: read-only rd: receive data data received by the spi interface is stored in this register right-justified. unused bits read zero. pcs: peripheral chip select in master mode only, these bits indicate the value on the npcs pins at the end of a transfer. otherwise, these bits read zero. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???? pcs 15 14 13 12 11 10 9 8 rd 76543210 rd
249 6042e?atarm?14-dec-06 at91sam7a3 preliminary 27.7.4 spi transmit data register name: spi_tdr access type: write-only td: transmit data data to be transmitted by the spi interface is stored in this register. information to be transmitted must be written to the transmit data register in a right-justified format. pcs: peripheral chip select this field is only used if variable peripheral select is active (ps = 1). if pcsdec = 0: pcs = xxx0 npcs[3:0] = 1110 pcs = xx01 npcs[3:0] = 1101 pcs = x011 npcs[3:0] = 1011 pcs = 0111 npcs[3:0] = 0111 pcs = 1111 forbidden (no peripheral is selected) (x = don?t care) if pcsdec = 1: npcs[3:0] output signals = pcs lastxfer: last transfer 0 = no effect. 1 = the current npcs will be deasserted afte r the character written in td has been tr ansferred. when c saat is set, this allows to close the communication with the current serial periph eral by raising the correspondi ng npcs line as soon as td transfer has completed. this field is only used if variable peripheral select is active (ps = 1). 31 30 29 28 27 26 25 24 ???????lastxfer 23 22 21 20 19 18 17 16 ???? pcs 15 14 13 12 11 10 9 8 td 76543210 td
250 6042e?atarm?14-dec-06 at91sam7a3 preliminary 27.7.5 spi status register name: spi_sr access type: read-only rdrf: receive data register full 0 = no data has been received since the last read of spi_rdr 1 = data has been received and the received data has been transferred from the serializer to spi_rdr since the last read of spi_rdr. tdre: transmit data register empty 0 = data has been written to spi_tdr and not yet transferred to the serializer. 1 = the last data written in the transmit data register has been transferred to the serializer. tdre equals zero when the spi is disabled or at reset. the spi enable command sets this bit to one. modf: mode fault error 0 = no mode fault has been detected since the last read of spi_sr. 1 = a mode fault occurred since the last read of the spi_sr. ovres: overrun error status 0 = no overrun has been detected since the last read of spi_sr. 1 = an overrun has occurred since the last read of spi_sr. an overrun occurs when spi_r dr is loaded at least twice from the serializer since the last read of the spi_rdr. endrx: end of rx buffer 0 = the receive counter register has not reached 0 since the last write in spi_rcr (1) or spi_rncr (1) . 1 = the receive counter register has reached 0 since the last write in spi_rcr (1) or spi_rncr (1) . endtx: end of tx buffer 0 = the transmit counter register has not reached 0 since the last write in spi_tcr (1) or spi_tncr (1) . 1 = the transmit counter register has reached 0 since the last write in spi_tcr (1) or spi_tncr (1) . rxbuff: rx buffer full 0 = spi_rcr (1) or spi_rncr (1) has a value other than 0. 1 = both spi_rcr (1) and spi_rncr (1) have a value of 0. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????spiens 15 14 13 12 11 10 9 8 ??????txemptynssr 76543210 txbufe rxbuff endtx endrx ovres modf tdre rdrf
251 6042e?atarm?14-dec-06 at91sam7a3 preliminary txbufe: tx buffer empty 0 = spi_tcr (1) or spi_tncr (1) has a value other than 0. 1 = both spi_tcr (1) and spi_tncr (1) have a value of 0. nssr: nss rising 0 = no rising edge detected on nss pin since last read. 1 = a rising edge occurred on nss pin since last read. txempty: transmission registers empty 0 = as soon as data is written in spi_tdr. 1 = spi_tdr and internal shifter are empty. if a transfer delay has been defined, txempty is set after the completion of such delay. spiens: spi enable status 0 = spi is disabled. 1 = spi is enabled. note: 1. spi_rcr, spi_rncr, spi_tcr, spi_tncr are physically located in the pdc.
252 6042e?atarm?14-dec-06 at91sam7a3 preliminary 27.7.6 spi interrupt enable register name: spi_ier access type: write-only rdrf: receive data register full interrupt enable tdre: spi transmit data regi ster empty interrupt enable modf: mode fault error interrupt enable ovres: overrun error interrupt enable endrx: end of receive buffer interrupt enable endtx: end of transmit buffer interrupt enable rxbuff: receive buffer full interrupt enable txbufe: transmit buffer empty interrupt enable txempty: transmission registers empty enable nssr: nss rising interrupt enable 0 = no effect. 1 = enables the corresponding interrupt. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ??????txemptynssr 76543210 txbufe rxbuff endtx endrx ovres modf tdre rdrf
253 6042e?atarm?14-dec-06 at91sam7a3 preliminary 27.7.7 spi interrupt disable register name: spi_idr access type: write-only rdrf: receive data register full interrupt disable tdre: spi transmit data register empty interrupt disable modf: mode fault error interrupt disable ovres: overrun error interrupt disable endrx: end of receive buffer interrupt disable endtx: end of transmit buffer interrupt disable rxbuff: receive buffer full interrupt disable txbufe: transmit buffer empty interrupt disable txempty: transmission registers empty disable nssr: nss rising interrupt disable 0 = no effect. 1 = disables the corresponding interrupt. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ??????txemptynssr 76543210 txbufe rxbuff endtx endrx ovres modf tdre rdrf
254 6042e?atarm?14-dec-06 at91sam7a3 preliminary 27.7.8 spi interrupt mask register name: spi_imr access type: read-only rdrf: receive data register full interrupt mask tdre: spi transmit data register empty interrupt mask modf: mode fault error interrupt mask ovres: overrun error interrupt mask endrx: end of receive buffer interrupt mask endtx: end of transmit buffer interrupt mask rxbuff: receive buffer full interrupt mask txbufe: transmit buffer empty interrupt mask txempty: transmission registers empty mask nssr: nss rising interrupt mask 0 = the corresponding interrupt is not enabled. 1 = the corresponding interrupt is enabled. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ??????txemptynssr 76543210 txbufe rxbuff endtx endrx ovres modf tdre rdrf
255 6042e?atarm?14-dec-06 at91sam7a3 preliminary 27.7.9 spi chip select register name: spi_csr0... spi_csr3 access type: read/write cpol: clock polarity 0 = the inactive state value of spck is logic level zero. 1 = the inactive state value of spck is logic level one. cpol is used to determine the inactive state value of the serial clock (spck). it is used with ncpha to produce the required clock/data relationship between master and slave devices. ncpha: clock phase 0 = data is changed on the leading edge of spck and captured on the following edge of spck. 1 = data is captured on the leading edge of spck and changed on the following edge of spck. ncpha determines which edge of spck causes data to c hange and which edge causes data to be captured. ncpha is used with cpol to produce the required clock/da ta relationship between master and slave devices. csaat: chip select active after transfer 0 = the peripheral chip select line rises as soon as the last transfer is achieved. 1 = the peripheral chip select does not rise after the last tr ansfer is achieved. it remains active until a new transfer is requested on a different chip select. bits: bits per transfer the bits field determines the number of data bits transferred. reserved values should not be used. 31 30 29 28 27 26 25 24 dlybct 23 22 21 20 19 18 17 16 dlybs 15 14 13 12 11 10 9 8 scbr 76543210 bits csaat ? ncpha cpol bits bits per transfer 0000 8 0001 9 0010 10 0011 11 0100 12 0101 13 0110 14 0111 15 1000 16 1001 reserved 1010 reserved 1011 reserved 1100 reserved 1101 reserved 1110 reserved 1111 reserved
256 6042e?atarm?14-dec-06 at91sam7a3 preliminary scbr: serial clock baud rate in master mode, the spi interface uses a modulus counter to derive the spck baud rate from the master clock mck. the baud rate is selected by writing a value from 1 to 255 in the scbr field. the following equations determine the spck baud rate: programming the scbr field at 0 is forbidden. triggering a trans fer while scbr is at 0 can le ad to unpredictable results. at reset, scbr is 0 and the user has to program it at a valid value before performing the first transfer. dlybs: delay before spck this field defines the delay from npcs valid to the first valid spck transition. when dlybs equals zero, the npcs valid to spck transition is 1/2 the spck clock period. otherwise, the following equations determine the delay: dlybct: delay between consecutive transfers this field defines the delay between two consecutive transfers with the same perip heral without removing the chip select. the delay is always inserted after each transfer and before removing the chip select if needed. when dlybct equals zero, no delay between consecutive transf ers is inserted and the clock keeps its duty cycle over the character transfers. otherwise, the following equat ion determines the delay: spck baudrate mck scbr -------------- - = delay before spck dlybs mck ------------------ - = delay between cons ecutive transfers 32 dlybct mck ------------------------------------ =
257 6042e?atarm?14-dec-06 at91sam7a3 preliminary 28. two-wire interface (twi) 28.1 overview the two-wire interface (twi) interconnects components on a unique two-wire bus, made up of one clock line and one data line with speeds of up to 400 kbits per second, based on a byte-ori- ented transfer format. it can be used with any atme l two-wire bus serial eeprom. the twi is programmable as a master with sequential or single-byte access. a configurable baud rate gen- erator permits the output data rate to be adapted to a wide range of core clock frequencies. 28.2 block diagram figure 28-1. block diagram 28.3 application block diagram figure 28-2. application block diagram apb bridge pmc mck two-wire interface pio aic twi interrupt twck twd host with twi interface twd twck at24lc16 u1 at24lc16 u2 lcd controller u3 slave 1 slave 2 slave 3 rr vdd
258 6042e?atarm?14-dec-06 at91sam7a3 preliminary 28.4 product dependencies 28.4.1 i/o lines description both twd and twck are bidirectional lines, connect ed to a positive supply voltage via a current source or pull-up resistor (see figure 28-2 on page 257 ). when the bus is free, both lines are high. the output stages of devices connected to the bus must have an open-drain or open-col- lector to perform the wired-and function. twd and twck pins may be multiplexed with pi o lines. to enable the twi, the programmer must perform the following steps: program the pio controller to: ? dedicate twd and twck as peripheral lines. ? define twd and twck as open-drain. 28.4.2 power management enable the peripheral clock. the twi interface may be clocked through the power management controller (pmc), thus the programmer must first configure the pmc to enable the twi clock. 28.4.3 interrupt the twi interface has an interrupt line connected to the advanced interrupt controller (aic). in order to handle interrupts, the aic must be programmed before configuring the twi. table 28-1. i/o lines description pin name pin description type twd two-wire serial data input/output twck two-wire serial clock input/output
259 6042e?atarm?14-dec-06 at91sam7a3 preliminary 28.5 functional description 28.5.1 transfer format the data put on the twd line must be 8 bits long. data is transferred msb first; each byte must be followed by an acknowledgement. the number of bytes per transfer is unlimited (see figure 28-4 on page 259 ). each transfer begins with a start condition and terminates with a stop condition (see figure 28-3 on page 259 ). a high-to-low transition on the twd line while twck is high defines the start condition. a low-to-high transition on the twd line while twck is high defines a stop condition. figure 28-3. start and stop conditions figure 28-4. transfer format 28.5.2 modes of operation the twi has two modes of operation: master transmitter mode master receiver mode the twi control register (twi_cr) allows configuration of the interface in master mode. in this mode, it generates the clock according to the value programmed in the clock waveform gener- ator register (twi_cwgr). this register defines the twck signal completely, enabling the interface to be adapted to a wide range of clocks. 28.5.3 transmitting data after the master initiates a start condition, it sends a 7-bit slave address, configured in the mas- ter mode register (dadr in twi_mmr), to notify the slave device. the bit following the slave address indicates the transfer direction (write or read). if this bit is 0, it indicates a write operation (transmit operation). if the bit is 1, it indica tes a request for data read (receive operation). the twi transfers require the slave to acknowledge each received byte. during the acknowl- edge clock pulse, the master releases the data line (high), enabling the slave to pull it down in order to generate the acknowledge. the master polls the data line during this clock pulse and twd twck start stop twd twck start address r/w ack data ack data ack stop
260 6042e?atarm?14-dec-06 at91sam7a3 preliminary sets the nak bit in the status register if the slave does not acknowledge the byte. as with the other status bits, an interrupt can be generated if enabled in the interrupt enable register (twi_ier). after writing in the transmit-holding register (twi_thr), setting the start bit in the control register starts the transmission. the data is shifted in the internal shifter and when an acknowledge is detected, the txrdy bit is set until a new write in the twi_thr (see figure 28- 6 below). the master generates a stop condition to end the transfer. the read sequence begins by setting the start bit. when the rxrdy bit is set in the status register, a character has been received in the receive-holding register (twi_rhr). the rxrdy bit is reset when reading the twi_rhr. the twi interface performs various transfer formats (7-bit slave address, 10-bit slave address). the three internal address bytes are configurable through the master mode register (twi_mmr). if the slave device supports only a 7-bit address, iadrsz must be set to 0. for a slave address higher than 7 bits, the user must configure the address size (iadrsz ) and set the other slave address bits in the internal address register (twi_iadr). figure 28-5. master write with one, two or three bytes internal address and one data byte figure 28-6. master write with one byte internal address and multiple data bytes figure 28-7. master read with one, two or three bytes internal address and one data byte s dadr w a iadr(23:16) a iadr(15:8) a iadr(7:0) a data a p s dadr w a iadr(15:8) a iadr(7:0) a p data a a iadr(7:0) a p data a s dadr w w d three bytes internal address two bytes internal address one byte internal address w d w d a iadr(7:0) a data a s dadr w data a p data a txcomp txrdy write thr write thr write thr write thr twd s dadr w a iadr(23:16) a iadr(15:8) a iadr(7:0) a s dadr w a iadr(15:8) a iadr(7:0) a a iadr(7:0) a s dadr w data n p s dadr r a s dadr r a data n p s dadr r a data n p twd twd twd three bytes internal address two bytes internal address one byte internal address
261 6042e?atarm?14-dec-06 at91sam7a3 preliminary figure 28-8. master read with one byte internal address and multiple data bytes s = start p = stop w = write r = read a = acknowledge n = not acknowledge dadr = device address iadr = internal address figure 28-9 below shows a byte write to an atmel at24lc512 eeprom. this demonstrates the use of internal addresses to access the device. figure 28-9. internal address usage 28.5.4 read/write flowcharts the following flowcharts shown in figure 28-10 on page 262 and in figure 28-11 on page 263 give examples for read and write operations in master mode. a polling or interrupt method can be used to check the status bits. the interrupt method requires that the interrupt enable register (twi_ier) be configured first. a iadr(7:0) a s dadr w s dadr r a data a data n p txcomp write start bit rxrdy write stop bit read rhr read rhr twd s t a r t m s b device address 0 l s b r / w a c k m s b w r i t e a c k a c k l s b a c k first word address second word address data s t o p
262 6042e?atarm?14-dec-06 at91sam7a3 preliminary figure 28-10. twi write in master mode set twi clock: twi_cwgr = clock set the control register: - master enable twi_cr = msen set the master mode register: - device slave address - internal address size - transfer direction bit write ==> bit mread = 0 internal address size = 0? load transmit register twi_thr = data to send start the transfer twi_cr = start stop the transfer twi_cr = stop read status register txrdy = 0? data to send? read status register txcomp = 0? end start set theinternal address twi_iadr = address ye s twi_thr = data to send ye s ye s ye s
263 6042e?atarm?14-dec-06 at91sam7a3 preliminary figure 28-11. twi read in master mode set twi clock: twi_cwgr = clock set the control register: - master enable - slave disable twi_cr = msen set the master mode register: - device slave address - internal address size - transfer direction bit read ==> bit mread = 0 internal address size = 0? start the transfer twi_cr = start stop the transfer twi_cr = stop read status register rxrdy = 0? data to read? read status register txcomp = 0? end start set the internal address twi_iadr = address ye s ye s ye s ye s
264 6042e?atarm?14-dec-06 at91sam7a3 preliminary 28.6 two-wire interface (t wi) user interface table 28-2. two-wire interface (twi) register mapping offset register name access reset value 0x0000 control register twi_cr write-only n/a 0x0004 master mode register twi_mmr read/write 0x0000 0x0008 reserved ? ? ? 0x000c internal address register twi_iadr read/write 0x0000 0x0010 clock waveform generator register twi_cwgr read/write 0x0000 0x0020 status register twi_sr read-only 0x0008 0x0024 interrupt enable register twi_ier write-only n/a 0x0028 interrupt disable register twi_idr write-only n/a 0x002c interrupt mask register twi_imr read-only 0x0000 0x0030 receive holding register twi_rhr read-only 0x0000 0x0034 transmit holding register twi_thr read/write 0x0000 0x0038-0x00fc reserved ? ? ?
265 6042e?atarm?14-dec-06 at91sam7a3 preliminary 28.6.1 twi control register register name :twi_cr access type: write-only start: send a start condition 0 = no effect. 1 = a frame beginning with a start bit is transmitted according to the features defined in the mode register. this action is necessary when the twi peripheral wants to read data from a slave. when configured in master mode with a write operation, a frame is sent with the mode register as soon as the user writes a character in the holding register. stop: send a stop condition 0 = no effect. 1 = stop condition is sent just after completing the current byte transmission in master read or write mode. in single data byte master read or write, the start and stop must both be set. in multiple data bytes master read or write, the stop must be set before ack/nack bit transmission. in master read mode, if a nack bit is received, the stop is automatically performed. in multiple data write operation, when both thr and shift register are empty, a stop condition is automatically sent. msen: twi master transfer enabled 0 = no effect. 1 = if msdis = 0, the master data transfer is enabled. msdis: twi master transfer disabled 0 = no effect. 1 = the master data transfer is disabled, all pending data is tr ansmitted. the shifter and holding characters (if they contain data) are transmitted in case of write operation. in read operation, the character being transferred must be completely received before disabling. swrst: software reset 0 = no effect. 1 = equivalent to a system reset. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ???????? 76543210 swrst ? ? ? msdis msen stop start
266 6042e?atarm?14-dec-06 at91sam7a3 preliminary 28.6.2 twi master mode register register name :twi_mmr address type : read/write iadrsz: internal device address size mread: master read direction 0 = master write direction. 1 = master read direction. dadr: device address the device address is used in master mode to access slave devices in read or write mode. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ?dadr 15 14 13 12 11 10 9 8 ???mread?? iadrsz 76543210 ???????? iadrsz[9:8] 0 0 no internal device address (byte command protocol) 0 1 one-byte internal device address 1 0 two-byte internal device address 1 1 three-byte internal device address
267 6042e?atarm?14-dec-06 at91sam7a3 preliminary 28.6.3 twi internal address register register name :twi_iadr access type : read/write iadr: internal address 0, 1, 2 or 3 bytes depending on iadrsz. ? low significant byte address in 10-bit mode addresses. 28.6.4 twi clock waveform generator register register name : twi_cwgr access type : read/write cldiv: clock low divider the scl low period is defined as follows: chdiv: clock high divider the scl high period is defined as follows: ckdiv: clock divider the ckdiv is used to increase both scl high and low periods. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 iadr 15 14 13 12 11 10 9 8 iadr 76543210 iadr 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ????? ckdiv 15 14 13 12 11 10 9 8 chdiv 76543210 cldiv t low cldiv ( 2 ckdiv () 3 ) + t mck = t high chdiv ( 2 ckdiv () 3 ) + t mck =
268 6042e?atarm?14-dec-06 at91sam7a3 preliminary 28.6.5 twi status register register name :twi_sr access type : read-only txcomp: transmission completed 0 = in master, during the length of the current frame. in slave, from start received to stop received. 1 = when both holding and shift registers are empty and stop condition has been sent (in master) or when msen is set (enable twi). rxrdy: receive hold ing register ready 0 = no character has been received since the last twi_rhr read operation. 1 = a byte has been received in the twi_rhr since the last read. txrdy: transmit holding register ready 0 = the transmit holding register has not been transferred into shift register. set to 0 when writing into twi_thr register. 1 = as soon as data byte is transferred from twi_thr to internal shifter or if a nack error is detected, txrdy is set at the same time as txcomp and nack. txrdy is also set when msen is set (enable twi). nack: not acknowledged 0 = each data byte has been correctly received by the far-end side twi slave component. 1 = a data byte has not been acknowledged by the slave compon ent. set at the same time as txcomp. reset after read. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ???????nack 76543210 ?????txrdyrxrdytxcomp
269 6042e?atarm?14-dec-06 at91sam7a3 preliminary 28.6.6 twi interrupt enable register register name :twi_ier access type: write-only txcomp: transmission completed rxrdy: receive hold ing register ready txrdy: transmit holding register ready nack: not acknowledge 0 = no effect. 1 = enables the corresponding interrupt. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ???????nack 76543210 ?????txrdyrxrdytxcomp
270 6042e?atarm?14-dec-06 at91sam7a3 preliminary 28.6.7 twi interrupt disable register register name :twi_idr access type: write-only txcomp: transmission completed rxrdy: receive hold ing register ready txrdy: transmit holding register ready nack: not acknowledge 0 = no effect. 1 = disables the corresponding interrupt. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ???????nack 76543210 ?????txrdyrxrdytxcomp
271 6042e?atarm?14-dec-06 at91sam7a3 preliminary 28.6.8 twi interrupt mask register register name :twi_imr access type : read-only txcomp: transmission completed rxrdy: receive hold ing register ready txrdy: transmit holding register ready nack: not acknowledge 0 = the corresponding interrupt is disabled. 1 = the corresponding interrupt is enabled. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ???????nack 76543210 ?????txrdyrxrdytxcomp
272 6042e?atarm?14-dec-06 at91sam7a3 preliminary 28.6.9 twi receive holding register register name : twi_rhr access type : read-only rxdata: master or slave receive holding data 28.6.10 twi transmit holding register register name :twi_thr access type: read/write txdata: master or slave transmit holding data 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ???????? 76543210 rxdata 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ???????? 76543210 txdata
273 6042e?atarm?14-dec-06 at91sam7a3 preliminary 29. universal synchronous asynchrono us receiver transceiver (usart) 29.0.1 overview the universal synchronous asynchronous receiv er transceiver (usart) provides one full duplex universal synchronous asynchronous serial link. data frame format is widely program- mable (data length, parity, number of stop bits) to support a maximum of standards. the receiver implements parity error, framing error and overrun error detection. the receiver time- out enables handling variable-length fr ames and the trans mitter timeguard facilitates commu- nications with slow remote devices. multidrop communications are also supported through address bit handling in reception and transmission. the usart features three test modes: remote loopback, local loopback and automatic echo. the usart supports specific operating modes providing interfaces on rs485 buses, with iso7816 t = 0 or t = 1 smart card slots and infrared transceivers. the hardware handshaking feature enables an out-of-band flow control by automatic management of the pins rts and cts. the usart supports the connection to the peripheral dma controller, which enables data transfers to the transmitter and from the receiver. the pdc provides chained buffer manage- ment without any intervention of the processor.
274 6042e?atarm?14-dec-06 at91sam7a3 preliminary 29.1 block diagram figure 29-1. usart block diagram peripheral dma controller channel channel aic receiver usart interrupt rxd txd sck usart pio controller cts rts transmitter baud rate generator user interface pmc mck slck div mck/div apb
275 6042e?atarm?14-dec-06 at91sam7a3 preliminary 29.2 application block diagram figure 29-2. application block diagram 29.3 i/o lines description smart card slot usart rs485 drivers differential bus irda transceivers field bus driver emv driver irda driver irlap rs232 drivers serial port serial driver ppp table 29-1. i/o line description name description type active level sck serial clock i/o txd transmit serial data i/o rxd receive serial data input cts clear to send input low rts request to send output low
276 6042e?atarm?14-dec-06 at91sam7a3 preliminary 29.4 product dependencies 29.4.1 i/o lines the pins used for interfacing the usart may be multiplexed with the pio lines. the program- mer must first program the pio controller to assign the desired usart pins to their peripheral function. if i/o lines of the usart are not used by the application, they can be used for other purposes by the pio controller. to prevent the txd line from falling when the usart is disabl ed, the use of an internal pull up is mandatory. 29.4.2 power management the usart is not continuously clocked. the programmer must first enable the usart clock in the power management controller (pmc) before using the usart. however, if the applica- tion does not require usart operations, the usart clock can be stopped when not needed and be restarted later. in this case, the usart will resume its op erations where it left off. configuring the usart does not require the usart clock to be enabled. 29.4.3 interrupt the usart interrupt line is connected on one of the internal sources of the advanced inter- rupt controller. using the usart interrupt requires the aic to be programmed first. note that it is not recommended to use the usart interrupt line in edge sensitive mode.
277 6042e?atarm?14-dec-06 at91sam7a3 preliminary 29.5 functional description the usart is capable of managing several ty pes of serial synchronous or asynchronous communications. it supports the following communication modes: 5- to 9-bit full-duplex asynchronous serial communication ? msb- or lsb-first ? 1, 1.5 or 2 stop bits ? parity even, odd, marked, space or none ? by 8 or by 16 over-sampling receiver frequency ? optional hardware handshaking ? optional break management ? optional multidrop serial communication high-speed 5- to 9-bit full-duplex synchronous serial communication ? msb- or lsb-first ? 1 or 2 stop bits ? parity even, odd, marked, space or none ? by 8 or by 16 over-sampling frequency ? optional hardware handshaking ? optional break management ? optional multidrop serial communication rs485 with driver control signal iso7816, t0 or t1 protocols for interfacing with smart cards ? nack handling, error counter with repetition and iteration limit infrared irda modulation and demodulation test modes ? remote loopback, local loopback, automatic echo 29.5.1 baud rate generator the baud rate generator provides the bit period clock named the baud rate clock to both the receiver and the transmitter. the baud rate generator clock source can be selected by setting the usclks field in the mode register (us_mr) between: the master clock mck a division of the master clock, the divider being product dependent, but generally set to 8 the external clock, available on the sck pin the baud rate generator is based upon a 16-bit divider, which is programmed with the cd field of the baud rate generator register (us_brgr). if cd is programmed at 0, the baud rate generator does not generate any clock. if cd is programmed at 1, the divider is bypassed and becomes inactive. if the external sck clock is selected, the duratio n of the low and high levels of the signal pro- vided on the sck pin must be longer than a master clock (mck) period. the frequency of the signal provided on sck must be at least 4.5 times lower than mck.
278 6042e?atarm?14-dec-06 at91sam7a3 preliminary figure 29-3. baud rate generator 29.5.1.1 baud rate in asynchronous mode if the usart is programmed to operate in asynchronous mode, the selected clock is first divided by cd, which is field programmed in th e baud rate generator register (us_brgr). the resulting clock is provided to the receiver as a sampling clock and then divided by 16 or 8, depending on the programming of the over bit in us_mr. if over is set to 1, the receiver sampling is 8 times higher than the baud rate clock. if over is cleared, the sampling is performed at 16 times the baud rate clock. the following formula performs the calculation of the baud rate. this gives a maximum baud rate of mck divided by 8, assuming that mck is the highest pos- sible clock and that over is programmed at 1. 29.5.1.2 baud rate calculation example table 29-2 shows calculations of cd to obtain a baud rate at 38400 bauds for different source clock frequencies. this table also shows the actual resulting baud rate and the error. mck/div 16-bit counter 0 baud rate clock cd cd sampling divider 0 1 >1 sampling clock reserved mck s ck usclks over sck sync sync usclks = 3 1 0 2 3 0 1 0 1 fidi baudrate selectedclock 82 over ? () cd () -------------------------------------------- = table 29-2. baud rate example (over = 0) source clock expected baud rate calculation result cd actual baud rate error mhz bit/s bit/s 3 686 400 38 400 6.00 6 38 400.00 0.00% 4 915 200 38 400 8.00 8 38 400.00 0.00% 5 000 000 38 400 8.14 8 39 062.50 1.70% 7 372 800 38 400 12.00 12 38 400.00 0.00% 8 000 000 38 400 13.02 13 38 461.54 0.16% 12 000 000 38 400 19.53 20 37 500.00 2.40% 12 288 000 38 400 20.00 20 38 400.00 0.00%
279 6042e?atarm?14-dec-06 at91sam7a3 preliminary the baud rate is calculated with the following formula: the baud rate error is calculated with the following formula. it is not recommended to work with an error higher than 5%. 29.5.1.3 baud rate in synchronous mode if the usart is programmed to operate in sync hronous mode, the selected clock is simply divided by the field cd in us_brgr. in synchronous mode, if the external clock is selected (usclks = 3), the clock is provided directly by the signal on the usart sck pin. no division is active. the value written in us_brgr has no effect. the external clock frequency must be at least 4.5 times lower than the system clock. when either the external clock sck or the inte rnal clock divided (mck/div) is selected, the value programmed in cd must be even if the user has to ensure a 50:50 mark/space ratio on the sck pin. if the internal clock mck is sele cted, the baud rate generator ensures a 50:50 duty cycle on the sck pin, even if the value programmed in cd is odd. 14 318 180 38 400 23.30 23 38 908.10 1.31% 14 745 600 38 400 24.00 24 38 400.00 0.00% 18 432 000 38 400 30.00 30 38 400.00 0.00% 24 000 000 38 400 39.06 39 38 461.54 0.16% 24 576 000 38 400 40.00 40 38 400.00 0.00% 25 000 000 38 400 40.69 40 38 109.76 0.76% 32 000 000 38 400 52.08 52 38 461.54 0.16% 32 768 000 38 400 53.33 53 38 641.51 0.63% 33 000 000 38 400 53.71 54 38 194.44 0.54% 40 000 000 38 400 65.10 65 38 461.54 0.16% 50 000 000 38 400 81.38 81 38 580.25 0.47% table 29-2. baud rate example (over = 0) (continued) source clock expected baud rate calculation result cd actual baud rate error baudrate mck cd 16 ? = error 1 expectedbaudrate actualbaudrate -------------------------------------------------- - ?? ?? ? = baudrate selectedclock cd ------------------------------------- - =
280 6042e?atarm?14-dec-06 at91sam7a3 preliminary 29.5.1.4 baud rate in iso 7816 mode the iso7816 specification defines the bit rate with the following formula: where: b is the bit rate di is the bit-rate adjustment factor fi is the clock frequency division factor f is the iso7816 clock frequency (hz) di is a binary value encoded on a 4-bit field, named di, as represented in table 29-3 . fi is a binary value encoded on a 4-bi t field, named fi, as represented in table 29-4 . table 29-5 shows the resulting fi/di ratio, which is the ratio between the iso7816 clock and the baud rate clock. if the usart is configured in iso7816 mode, the clock selected by the usclks field in the mode register (us_mr) is first divided by the value programmed in the field cd in the baud rate generator register (us_brgr). the resulting clock can be provided to the sck pin to feed the smart card clock inputs. this means that the clko bit can be set in us_mr. this clock is then divided by the value programmed in the fi_di_ratio field in the fi_di_ratio register (us_fidi). this is performed by the sampling divider, which performs a division by up to 2047 in iso7816 mode. the non-integer values of the fi/di ratio are not sup- ported and the user must program the fi_di_rati o field to a value as close as possible to the expected value. b di fi ----- - f = table 29-3. binary and decimal values for di di field 0001 0010 0011 0100 0101 0110 1000 1001 di (decimal)1 2 4 8 163212 20 table 29-4. binary and decimal values for fi fi field 0000 0001 0010 0011 0100 0101 0110 1001 1010 1011 1100 1101 fi (decimal 372 372 558 744 1116 1488 1860 512 768 1024 1536 2048 table 29-5. possible values for the fi/di ratio fi/di 372 558 774 1116 1488 1806 512 768 1024 1536 2048 1 372 558 744 1116 1488 1860 512 768 1024 1536 2048 2 186 279 372 558 744 930 256 384 512 768 1024 4 93 139.5 186 279 372 465 128 192 256 384 512 8 46.5 69.75 93 139.5 186 232.5 64 96 128 192 256 16 23.25 34.87 46.5 69.75 93 116.2 32 48 64 96 128 32 11.62 17.43 23.25 34.87 46.5 58.13 16 24 32 48 64 12 31 46.5 62 93 124 155 42.66 64 85.33 128 170.6 20 18.6 27.9 37.2 55.8 74.4 93 25.6 38.4 51.2 76.8 102.4
281 6042e?atarm?14-dec-06 at91sam7a3 preliminary the fi_di_ratio field resets to the value 0x174 (372 in decimal) and is the most common divider between the iso7816 clock and the bit rate (fi = 372, di = 1). figure 29-4 shows the relation between the elementary time unit, corresponding to a bit time, and the iso 7816 clock. figure 29-4. elementary time unit (etu) 29.5.2 receiver and transmitter control after reset, the receiver is disabled. the user mu st enable the receiver by setting the rxen bit in the control register (us_cr). however, th e receiver registers can be programmed before the receiver clock is enabled. after reset, the transmitter is di sabled. the user must enable it by setting the txen bit in the control register (us_cr). however, the transmitter registers can be programmed before being enabled. the receiver and the transmitter can be enabled together or independently. at any time, the software can perform a reset on the receiver or the transmitter of the usart by setting the corresponding bit, rstrx and rs ttx respectively, in the control register (us_cr). the reset commands have the same effect as a hardware reset on the correspond- ing logic. regardless of what the receiver or the transmitter is performing, the communication is immediately stopped. the user can also independently disable the rece iver or the transmitter by setting rxdis and txdis respectively in us_cr. if the receiver is disabled during a character reception, the usart waits until the end of reception of the current character, then the reception is stopped. if the transmitter is disabled while it is operat ing, the usart waits the end of transmission of both the current character and character being stored in the transmit holding register (us_thr). if a timeguard is programmed, it is handled normally. 29.5.3 synchronous and asynchronous modes 29.5.3.1 transmitter operations the transmitter performs the same in both synchronous and asynchronous operating modes (sync = 0 or sync = 1). one start bit, up to 9 data bits, one optional parity bit and up to two stop bits are successively shifted out on the txd pin at each falling edge of the programmed serial clock. the number of data bits is selected by the chrl field and the mode 9 bit in the mode regis- ter (us_mr). nine bits are selected by setting the mode 9 bit regardless of the chrl field. the parity bit is set according to the par fiel d in us_mr. the even, odd, space, marked or 1 etu iso7816 clock on sck iso7816 i/o line on txd fi_di_ratio iso7816 clock cycles
282 6042e?atarm?14-dec-06 at91sam7a3 preliminary none parity bit can be configured. the msbf fi eld in us_mr configures which data bit is sent first. if written at 1, the most significant bit is sent first. at 0, the less significant bit is sent first. the number of stop bits is selected by the nbstop field in us_mr. the 1.5 stop bit is sup- ported in asynchronous mode only. figure 29-5. character transmit the characters are sent by writing in the tr ansmit holding register (us_thr). the transmit- ter reports two status bits in the channel status register (us_csr): txrdy (transmitter ready), which indicates that us_thr is empt y and txempty, which indicates that all the characters written in us_thr have been proces sed. when the current character processing is completed, the last character written in us_thr is transferred into the shift register of the transmitter and us_thr becomes empty, thus txrdy raises. both txrdy and txempty bits are low since the transmitter is disabled. writing a character in us_thr while txrdy is active has no ef fect and the written character is lost. figure 29-6. transmitter status 29.5.3.2 asynchronous receiver if the usart is programmed in asynchronous operating mode (sync = 0), the receiver over- samples the rxd input line. the oversampling is either 16 or 8 times the baud rate clock, depending on the over bit in the mode register (us_mr). the receiver samples the rxd line. if the line is sampled during one half of a bit time at 0, a start bit is detected and data, parity and stop bi ts are successively sampled on the bit rate clock. if the oversampling is 16, (over at 0), a start is detected at the eighth sample at 0. then, data bits, parity bit and stop bit are sampled on ea ch 16 sampling clock cycle. if the oversampling is d0 d1 d2 d3 d4 d5 d6 d7 txd start bit parity bit stop bit example: 8-bit, parity enabled one stop baud rate clock d0 d1 d2 d3 d4 d5 d6 d7 txd start bit parity bit stop bit baud rate clock start bit write us_thr d0 d1 d2 d3 d4 d5 d6 d7 parity bit stop bit txrdy txempty
283 6042e?atarm?14-dec-06 at91sam7a3 preliminary 8 (over at 1), a start bit is detected at the fourth sample at 0. then, data bits, parity bit and stop bit are sampled on each 8 sampling clock cycle. the number of data bits, first bit sent and parity mode are selected by the same fields and bits as the transmitter, i.e. respectively chrl, mode9, msbf and par. for the synchronization mechanism only , the number of stop bits has no effect on the receiver as it considers only one stop bit, regardless of the field nbstop, so that resynchronization between the receiver and the transmitter can occur. moreover, as soon as th e stop bit is sampled, the receiver starts looking for a new start bit so that resynchronization can also be accomplished when the trans- mitter is operating with one stop bit. figure 29-7 and figure 29-8 illustrate start detection and character reception when usart operates in asynchronous mode. figure 29-7. asynchronous start detection figure 29-8. asynchronous character reception sampling clock (x16) rxd start detection sampling baud rate clock rxd start rejection sampling 12345678 12345670 1234 12345678 9 10111213141516 d0 sampling d0 d1 d2 d3 d4 d5 d6 d7 rxd parity bit stop bit example: 8-bit, parity enabled baud rate clock start detection 16 samples 16 samples 16 samples 16 samples 16 samples 16 samples 16 samples 16 samples 16 samples 16 samples
284 6042e?atarm?14-dec-06 at91sam7a3 preliminary 29.5.3.3 synchronous receiver in synchronous mode (sync = 1), the receiver samples the rxd signal on each rising edge of the baud rate clock. if a low level is detected, it is considered as a start. all data bits, the par- ity bit and the stop bits are sampled and the receiver waits for the next start bit. synchronous mode operations provide a hi gh speed trans fer capability. configuration fields and bits are the same as in asynchronous mode. figure 29-9 illustrates a character rece ption in synchronous mode. figure 29-9. synchronous mode character reception 29.5.3.4 receiver operations when a character reception is completed, it is transferred to the receive holding register (us_rhr) and the rxrdy bit in the status regi ster (us_csr) rises. if a character is com- pleted while the rxrdy is set, the ovre (overrun error) bit is set. the last character is transferred into us_rhr and overwrites the previ ous one. the ovre bit is cleared by writing the control register (us_cr) with the rststa (reset status) bit at 1. figure 29-10. receiver status d0 d1 d2 d3 d4 d5 d6 d7 rxd start sampling parity bit stop bit example: 8-bit, parity enabled 1 stop baud rate clock d0 d1 d2 d3 d4 d5 d6 d7 rxd start bit parity bit stop bit baud rate clock write us_cr rxrdy ovre d0 d1 d2 d3 d4 d5 d6 d7 start bit parity bit stop bit rststa = 1 read us_rhr
285 6042e?atarm?14-dec-06 at91sam7a3 preliminary 29.5.3.5 parity the usart supports five parity modes selected by programming the par field in the mode register (us_mr). the par field also enables the multidrop mode, see ?multidrop mode? on page 286 . even and odd parity bit generation and error detection are supported. if even parity is selected, the parity generator of the transmitter drives the parity bit at 0 if a number of 1s in the character data bit is even, a nd at 1 if the number of 1s is odd. accordingly, the receiver parity checker counts the number of received 1s and reports a parity error if the sampled parity bit does not correspond. if odd parity is selected, the parity generator of the transmitter drives the parity bit at 1 if a number of 1s in the character data bit is even, and at 0 if the number of 1s is odd. accordingly, the receiver parity checker counts the number of received 1s and reports a parity error if the samp led parity bit does not correspond. if the mark parity is used, the parity generator of the transmitte r drives the parity bit at 1 for all characters. the receiver parity checker reports an error if the parity bit is sampled at 0. if the space parity is used, the parity generator of the transmitter driv es the parity bit at 0 for all characters. the receiver parity checker reports an error if the parity bit is sampled at 1. if parity is disabled, the transmitter does not generate any parity bit and the receiver does not report any parity error. table 29-6 shows an example of the parity bit for the character 0x41 (character ascii ?a?) depending on the configuration of the usart. because there are two bits at 1, 1 bit is added when a parity is odd, or 0 is added when a parity is even. when the receiver detects a parity error, it sets the pare (parity error) bit in the channel sta- tus register (us_csr). the pare bit can be cleared by writing the control register (us_cr) with the rststa bit at 1. figure 29-11 illustrates the parity bit st atus setting and clearing. table 29-6. parity bit examples character hexa binary parity bit parity mode a 0x41 0100 0001 1 odd a 0x41 0100 0001 0 even a 0x41 0100 0001 1 mark a 0x41 0100 0001 0 space a 0x41 0100 0001 none none
286 6042e?atarm?14-dec-06 at91sam7a3 preliminary figure 29-11. parity error 29.5.3.6 multidrop mode if the par field in the mode register (us_mr) is programmed to the value 0x6 or 0x07, the usart runs in multidrop mode. this mode differentiates the data characters and the address characters. data is transmitted with the parity bit at 0 and addresses are transmitted with the parity bit at 1. if the usart is configured in multidrop mode, the receiver sets the pare parity error bit when the parity bit is high and the transmitter is able to send a character with the parity bit high when the control register is written with the senda bit at 1. to handle parity error, the pare bit is cleared when the control register is written with the bit rststa at 1. the transmitter sends an address byte (parity bi t set) when senda is written to us_cr. in this case, the next byte written to us_thr is transmitted as an address. any character written in us_thr without having written the command senda is transmitted normally with the parity at 0. 29.5.3.7 transmitter timeguard the timeguard feature enables the usar t interface with slow remote devices. the timeguard function enables the transmitter to insert an idle state on the txd line between two characters. this idle state actually acts as a long stop bit. the duration of the idle state is programmed in the tg field of the transmitter timeguard reg- ister (us_ttgr). when this field is pr ogrammed at zero no timeguard is generated. otherwise, the transmitter holds a high level on txd after each transmitted byte during the number of bit periods programmed in tg in addition to the number of stop bits. as illustrated in figure 29-12 , the behavior of txrdy and txempty status bits is modified by the programming of a timeguard. txrdy rises only when the start bit of the next character is sent, and thus remains at 0 during the timegua rd transmission if a character has been written in us_thr. txempty remains low until the timeguard transmission is completed as the time- guard is part of the current character being transmitted. d0 d1 d2 d3 d4 d5 d6 d7 rxd start bit bad parity bit stop bit baud rate clock write us_cr pare rxrdy rststa = 1
287 6042e?atarm?14-dec-06 at91sam7a3 preliminary figure 29-12. timeguard operations table 29-7 indicates the maximum length of a timeguard period that the transmitter can handle in relation to the function of the baud rate. 29.5.3.8 receiver time-out the receiver time-out provides support in handling variable-length frames. this feature detects an idle condition on the rxd line. when a time-out is detected, the bit timeout in the channel status register (us_csr) rises and can generate an interrupt, thus indicating to the driver an end of frame. the time-out delay period (during which the receiver waits for a new character) is programmed in the to field of the receiver time-out register (us_rtor). if the to field is programmed at 0, the receiver time-out is disabled and no time-out is detected. the timeout bit in us_csr remains at 0. otherwis e, the receiver loads a 16-bit counter with the value pro- grammed in to. this counter is decremented at each bit period and reloaded each time a new character is received. if the c ounter reaches 0, the timeout bit in the status register rises. the user can either: stop the counter clock until a new character is received. this is performed by writing the control register (us_cr) with the sttto (start time-out) bit at 1. in this case, the idle d0 d1 d2 d3 d4 d5 d6 d7 txd start bit parity bit stop bit baud rate clock start bit tg = 4 write us_thr d0 d1 d2 d3 d4 d5 d6 d7 parity bit stop bit txrdy txempty tg = 4 table 29-7. maximum timeguard length depending on baud rate baud rate bit time timeguard bit/sec s ms 1 200 833 212.50 9 600 104 26.56 14400 69.4 17.71 19200 52.1 13.28 28800 34.7 8.85 33400 29.9 7.63 56000 17.9 4.55 57600 17.4 4.43 115200 8.7 2.21
288 6042e?atarm?14-dec-06 at91sam7a3 preliminary state on rxd before a new character is receiv ed will not provide a time -out. this prevents having to handle an interrupt before a character is received and allows waiting for the next idle state on rxd after a frame is received. obtain an interrupt while no character is receiv ed. this is performed by writing us_cr with the retto (reload and start time-out) bit at 1. if retto is performed, the counter starts counting down immediately from the value to. this enables generation of a periodic interrupt so that a user time-out can be handled, for example when no key is pressed on a keyboard. if sttto is performed, the counter clock is stopped until a first character is received. the idle state on rxd before the start of the frame does not provide a time-out. this prevents having to obtain a periodic interrupt and enables a wait of the end of frame when the idle state on rxd is detected. if retto is performed, the counter starts counting down immediately from the value to. this enables generation of a periodic interrupt so that a user time-out can be handled, for example when no key is pressed on a keyboard. figure 29-13 shows the block diagram of the receiver time-out feature. figure 29-13. receiver time-out block diagram table 29-8 gives the maximum time-out period for some standard baud rates. table 29-8. maximum time-out period baud rate bit time time-out bit/sec s ms 600 1 667 109 225 1 200 833 54 613 2 400 417 27 306 4 800 208 13 653 9 600 104 6 827 14400 69 4 551 19200 52 3 413 28800 35 2 276 33400 30 1 962 16-bit time-out counter 0 to timeout baud rate clock = character received retto load clock 16-bit value sttto dq 1 clear
289 6042e?atarm?14-dec-06 at91sam7a3 preliminary 29.5.3.9 framing error the receiver is capable of detecting framing er rors. a framing error happens when the stop bit of a received character is detected at level 0. this can occur if the receiver and the transmitter are fully desynchronized. a framing error is reported on the frame bit of the channel status register (us_csr). the frame bit is asserted in the middle of the stop bi t as soon as the framing error is detected. it is cleared by writing the control regist er (us_cr) with the rststa bit at 1. figure 29-14. framing error status 29.5.3.10 transmit break the user can request the transmitter to generate a break condition on the txd line. a break condition drives the txd line low during at least one complete character. it appears the same as a 0x00 character sent with the parity and the stop bits at 0. however, the transmitter holds the txd line at least during one character until t he user requests the break condition to be removed. a break is transmitted by writing the control regi ster (us_cr) with the sttbrk bit at 1. this can be performed at any time, either while the transmitter is empty (no character in either the shift register or in us_thr) or when a character is being transmitted. if a break is requested while a character is being shifted out, the characte r is first completed before the txd line is held low. once sttbrk command is requested further sttbrk commands are ignored until the end of the break is completed. the break condition is removed by writing us_cr with the stpbrk bit at 1. if the stpbrk is requested before the end of the minimum break duration (one character, including start, data, parity and stop bits), the transmitter ensures that the break condition completes. 56000 18 1 170 57600 17 1 138 200000 5 328 table 29-8. maximum time-out period (continued) baud rate bit time time-out d0 d1 d2 d3 d4 d5 d6 d7 rxd start bit parity bit stop bit baud rate clock write us_cr frame rxrdy rststa = 1
290 6042e?atarm?14-dec-06 at91sam7a3 preliminary the transmitter considers the break as though it is a character, i.e. the sttbrk and stpbrk commands are taken into account only if the txrdy bit in us_csr is at 1 and the start of the break condition clears the txrdy and txempty bits as if a character is processed. writing us_cr with the both sttbrk and stpb rk bits at 1 can lead to an unpredictable result. all stpbrk commands requested without a previous sttbrk command are ignored. a byte written into the transmit holding register while a break is pending, but not started, is ignored. after the break condition, the transmitter returns the txd line to 1 for a minimum of 12 bit times. thus, the transmitter ensures that the remote receiver detects correctly the end of break and the start of the next character. if the timeguard is programmed with a value higher than 12, the txd line is held high for the timeguard period. after holding the txd line for this period, the transmitter resumes normal operations. figure 29-15 illustrates the effect of both the start break (sttbrk) and stop break (stp- brk) commands on the txd line. figure 29-15. break transmission 29.5.3.11 receive break the receiver detects a break condition when all data, parity and stop bits are low. this corre- sponds to detecting a framing error with data at 0x00, but frame remains low. when the low stop bit is detected, the receiver asserts the rxbrk bit in us_csr. this bit may be cleared by writing the control re gister (us_cr) with the bit rststa at 1. an end of receive break is detected by a high level for at least 2/16 of a bit period in asynchro- nous operating mode or one sample at high level in synchronous operating mode. the end of break detection also asserts the rxbrk bit. 29.5.3.12 hardware handshaking the usart features a hardware handshaking out-of-band flow control. the rts and cts pins are used to connect with the remote device, as shown in figure 29-16 . d0 d1 d2 d3 d4 d5 d6 d7 txd start bit parity bit stop bit baud rate clock write us_cr txrdy txempty stpbrk = 1 sttbrk = 1 break transmission end of break
291 6042e?atarm?14-dec-06 at91sam7a3 preliminary figure 29-16. connection with a remote device for hardware handshaking setting the usart to operate with hardware handshaking is performed by writing the usart_mode field in the mode register (us_mr) to the value 0x2. the usart behavior when hardware handshaking is enabled is the same as the behavior in standard synchronous or asynchronous mode, exce pt that the receiver drives the rts pin as described below and the level on the cts pin modifies the behavior of the transmitter as described below. using this mode requires using the pdc channel for reception. the transmit- ter can handle hardware handshaking in any case. figure 29-17 shows how the receiver operates if ha rdware handshaking is enabled. the rts pin is driven high if the receiver is disabled and if the status rxbuff (receive buffer full) coming from the pdc channel is high. normally, the remote device does not start transmitting while its cts pin (driven by rts) is high. as soon as the receiver is enabled, the rts falls, indicating to the remote device that it can start transmitting. defining a new buffer to the pdc clears the status bit rxbuff and, as a result, asserts the pin rts low. figure 29-17. receiver behavior when operating with hardware handshaking figure 29-18 shows how the transmitter operates if hardware handshaking is enabled. the cts pin disables the transmitter. if a character is being processing, the transmitter is disabled only after the completion of the current character and transmission of the next character hap- pens as soon as the pin cts falls. figure 29-18. transmitter behavior when operating with hardware handshaking usart txd cts remote device rxd txd rxd rts rts cts rts rxbuff write us_cr rxen = 1 rxd rxdis = 1 cts txd
292 6042e?atarm?14-dec-06 at91sam7a3 preliminary 29.5.4 iso7816 mode the usart features an iso7816-compatible operating mode. this mode permits interfacing with smart cards and security access modules (sam) communicating through an iso7816 link. both t = 0 and t = 1 protocols defined by the iso7816 specification are supported. setting the usart in iso7816 mode is performed by writing the usart_mode field in the mode register (us_mr) to the value 0x4 for protocol t = 0 and to the value 0x5 for protocol t = 1. 29.5.4.1 iso7816 mode overview the iso7816 is a half duplex communication on only one bidirectional line. the baud rate is determined by a division of the clock provided to the remote device (see ?baud rate genera- tor? on page 277 ). the usart connects to a smart card as shown in figure 29-19 . the txd line becomes bidi- rectional and the baud rate generator feeds the iso7816 clock on the sck pin. as the txd pin becomes bidirectional, its output remains dr iven by the output of the transmitter but only when the transmitter is active wh ile its input is directed to the input of the receiver. the usart is considered as the master of the communication as it generates the clock. figure 29-19. connection of a smart card to the usart when operating in iso7816, either in t = 0 or t = 1 modes, the character format is fixed. the configuration is 8 data bits, even parity and 1 or 2 stop bits, regardless of the values pro- grammed in the chrl, mode9, par and chmo de fields. msbf can be used to transmit lsb or msb first. parity bit (par) can be used to transmit in normal or inverse mode. refer to ?usart mode register? on page 303 and ?par: parity type? on page 304 . the usart cannot operate concurrently in both receiver and transmitter modes as the com- munication is unidirectional at a time. it has to be configured according to the required mode by enabling or disabling either the receiver or the transmitter as desired. enabling both the receiver and the transmitter at the same time in iso7816 mode may lead to unpredictable results. the iso7816 specification defines an inverse trans mission format. data bits of the character must be transmitted on the i/o line at their negative value. the usart does not support this format and the user has to perform an exclusive or on the data before writing it in the trans- mit holding register (us_thr) or after reading it in the receive hold ing register (us_rhr). 29.5.4.2 protocol t = 0 in t = 0 protocol, a character is made up of one start bit, eight data bits, one parity bit and one guard time, which lasts two bit times. the transmitter shifts out the bits and does not drive the i/o line during the guard time. smart card sck clk txd i/o usart
293 6042e?atarm?14-dec-06 at91sam7a3 preliminary if no parity error is detected, the i/o line remains at 1 during the guard time and the transmitter can continue with the transmission of the next character, as shown in figure 29-20 . if a parity error is detected by the receiver, it drives the i/o line at 0 during the guard time, as shown in figure 29-21 . this error bit is also named nack, for non acknowledge. in this case, the character lasts 1 bit time more, as the guard time length is the same and is added to the error bit time which lasts 1 bit time. when the usart is the receiver and it detects an error, it does not load the erroneous charac- ter in the receive holding register (us_rhr). it appropriately sets the pare bit in the status register (us_sr) so that the software can handle the error. figure 29-20. t = 0 protocol without parity error figure 29-21. t = 0 protocol with parity error 29.5.4.3 receive error counter the usart receiver also records the total number of errors. this can be read in the number of error (us_ner) register. the nb_errors field can record up to 255 errors. reading us_ner automatically clears the nb_errors field. 29.5.4.4 receive nack inhibit the usart can also be configur ed to inhibit an error. this can be achieved by setting the inack bit in the mode register (us_mr). if inack is at 1, no error signal is driven on the i/o line even if a parity bit is detected, but the inac k bit is set in the status register (us_sr). the inack bit can be cleared by writing the control register (us_cr) with the rstnack bit at 1. moreover, if inack is set, the erroneous received character is stored in the receive holding register, as if no error occurred. however, the rxrdy bit does not raise. 29.5.4.5 transmit character repetition when the usart is transmitting a character and gets a nack, it can automatically repeat the character before moving on to the next one. repetition is enabled by writing the max_iteration field in the mode register (us_mr) at a value higher than 0. each charac- ter can be transmitted up to eight times; the first transmission plus seven repetitions. d0 d1 d2 d3 d4 d5 d6 d7 rxd parity bit baud rate clock start bit guard time 1 next start bit guard time 2 d0 d1 d2 d3 d4 d5 d6 d7 i/o parity bit baud rate clock start bit guard time 1 start bit guard time 2 d0 d1 error repetition
294 6042e?atarm?14-dec-06 at91sam7a3 preliminary if max_iteration does not equal zero, the u sart repeats the character as many times as the value loaded in max_iteration. when the usart repetition number reaches m ax_iteration, the iterat ion bit is set in the channel status register (us_csr). if the repetition of the character is acknowledged by the receiver, the repetitions are stopped and the iteration counter is cleared. the iteration bit in us_csr can be cleared by writing the control register with the rsit bit at 1. 29.5.4.6 disable successive receive nack the receiver can limit the number of successive nacks sent back to the remote transmitter. this is programmed by setting the bit dsnack in the mode register (us_mr). the maximum number of nack transmitted is programmed in the max_iteration field. as soon as max_iteration is reached, the character is cons idered as correct, an acknowledge is sent on the line and the iteration bit in the channel status register is set. 29.5.4.7 protocol t = 1 when operating in iso7816 protocol t = 1, the transmission is similar to an asynchronous for- mat with only one stop bit. the parity is generated when transmitting and checked when receiving. parity error detection sets the pare bit in the channel status register (us_csr). 29.5.5 irda mode the usart features an irda mode supplying half-duplex point-to-point wireless communica- tion. it embeds the modulator and demodulator which allows a glueless connection to the infrared transceivers, as shown in figure 29-22 . the modulator and demodulator are compli- ant with the irda specification version 1.1 and support data transfer speeds ranging from 2.4 kb/s to 115.2 kb/s. the usart irda mode is enabled by setting t he usart_mode field in the mode register (us_mr) to the value 0x8. the irda filter register (us_if) allows configuring the demodula- tor filter. the usart transmitter and receiver operate in a normal asynchronous mode and all parameters are accessible. note that the modulator and the demodulator are activated. figure 29-22. connection to irda transceivers the receiver and the transmitter must be enabled or disabled according to the direction of the transmission to be managed. irda transceivers rxd rx txd tx usart demodulator modulator receiver transmitter
295 6042e?atarm?14-dec-06 at91sam7a3 preliminary 29.5.5.1 irda modulation for baud rates up to and including 115.2 kbits/sec, the rzi modulation scheme is used. ?0? is represented by a light pulse of 3/16th of a bit time. some examples of signal pulse duration are shown in table 29-9 . figure 29-23 shows an example of character transmission. figure 29-23. irda modulation 29.5.5.2 irda baud rate table 29-10 gives some examples of cd values, baud rate error and pulse duration. note that the requirement on the maximum acceptable error of 1.87% must be met. table 29-9. irda pulse duration baud rate pulse duration (3/16) 2.4 kb/s 78.13 s 9.6 kb/s 19.53 s 19.2 kb/s 9.77 s 38.4 kb/s 4.88 s 57.6 kb/s 3.26 s 115.2 kb/s 1.63 s bit period bit period 3 16 start bit data bits stop bit 0 0 0 0 0 1 1 1 1 1 transmitter output txd table 29-10. irda baud rate error peripheral clock baud rate cd baud rate error pulse time 3 686 400 115 200 2 0.00% 1.63 20 000 000 115 200 11 1.38% 1.63 32 768 000 115 200 18 1.25% 1.63 40 000 000 115 200 22 1.38% 1.63 3 686 400 57 600 4 0.00% 3.26 20 000 000 57 600 22 1.38% 3.26 32 768 000 57 600 36 1.25% 3.26 40 000 000 57 600 43 0.93% 3.26 3 686 400 38 400 6 0.00% 4.88 20 000 000 38 400 33 1.38% 4.88
296 6042e?atarm?14-dec-06 at91sam7a3 preliminary 29.5.5.3 irda demodulator the demodulator is based on the irda receive filter comprised of an 8-bit down counter which is loaded with the value progra mmed in us_if. when a falling e dge is detected on the rxd pin, the filter counter starts counting down at the master clock (mck) speed. if a rising edge is detected on the rxd pin, the counter stops and is reloaded with us_if. if no rising edge is detected when the counter reaches 0, the input of the receiver is driven low during one bit time. figure 29-24 illustrates the operations of the irda demodulator. figure 29-24. irda demodulator operations as the irda mode uses the same logic as the iso7816, note that the fi_di_ratio field in us_fidi must be set to a value higher than 0 in order to assure irda communications operate correctly. 32 768 000 38 400 53 0.63% 4.88 40 000 000 38 400 65 0.16% 4.88 3 686 400 19 200 12 0.00% 9.77 20 000 000 19 200 65 0.16% 9.77 32 768 000 19 200 107 0.31% 9.77 40 000 000 19 200 130 0.16% 9.77 3 686 400 9 600 24 0.00% 19.53 20 000 000 9 600 130 0.16% 19.53 32 768 000 9 600 213 0.16% 19.53 40 000 000 9 600 260 0.16% 19.53 3 686 400 2 400 96 0.00% 78.13 20 000 000 2 400 521 0.03% 78.13 32 768 000 2 400 853 0.04% 78.13 table 29-10. irda baud rate error (continued) peripheral clock baud rate cd baud rate error pulse time mck rxd receiver input pulse rejected 65432 6 1 65432 0 pulse accepted counter value
297 6042e?atarm?14-dec-06 at91sam7a3 preliminary 29.5.6 rs485 mode the usart features the rs485 mode to enable line driver control. while operating in rs485 mode, the usart behaves as though in asynchronous or synchronous mode and configura- tion of all the parameters is possible. the differenc e is that the rts pin is driven high when the transmitter is operating. the behavior of the rts pin is controlled by the txempty bit. a typ- ical connection of the usart to a rs485 bus is shown in figure 29-25 . figure 29-25. typical connection to a rs485 bus the usart is set in rs485 mode by programm ing the usart_mode field in the mode reg- ister (us_mr) to the value 0x1. the rts pin is at a level inverse to the txempty bit. significantly, the rts pin remains high when a timeguard is programmed so that the line can remain driven after the last character completion. figure 29-26 gives an example of the rts waveform during a character transmis- sion when the timeguard is enabled. figure 29-26. example of rts drive with timeguard usart rts txd rxd differential bus d0 d1 d2 d3 d4 d5 d6 d7 txd start bit parity bit stop bit baud rate clock tg = 4 write us_thr txrdy txempty rts
298 6042e?atarm?14-dec-06 at91sam7a3 preliminary 29.5.7 test modes the usart can be programmed to operate in three different test modes. the internal loop- back capability allows on-board diagnostics. in the loopback mode the usart interface pins are disconnected or not and reconfigured for loopback internally or externally. 29.5.7.1 normal mode normal mode connects the rxd pin on the receiver input and the transmitter output on the txd pin. figure 29-27. normal mode configuration 29.5.7.2 automatic echo mode automatic echo mode allows bit-by-bit retransmission. when a bit is received on the rxd pin, it is sent to the txd pin, as shown in figure 29-28 . programming the transmitter has no effect on the txd pin. the rxd pin is still connected to the receiver input, thus the receiver remains active. figure 29-28. automatic echo mode configuration 29.5.7.3 local loopback mode local loopback mode connects the output of the transmitter directly to the input of the receiver, as shown in figure 29-29 . the txd and rxd pins are not used. the rxd pin has no effect on the receiver and the txd pin is continuously driven high, as in idle state. figure 29-29. local loopback mode configuration receiver transmitter rxd txd receiver transmitter rxd txd receiver transmitter rxd txd 1
299 6042e?atarm?14-dec-06 at91sam7a3 preliminary 29.5.7.4 remote loopback mode remote loopback mode directly connects the rxd pin to the txd pin, as shown in figure 29- 30 . the transmitter and the receiver are disabled an d have no effect. this mode allows bit-by- bit retransmission. figure 29-30. remote loopback mode configuration receiver transmitter rxd txd 1
300 6042e?atarm?14-dec-06 at91sam7a3 preliminary 29.6 usart user interface table 29-11. usart memory map offset register name access reset state 0x0000 control register us_cr write-only ? 0x0004 mode register us_mr read/write ? 0x0008 interrupt enable register us_ier write-only ? 0x000c interrupt disable register us_idr write-only ? 0x0010 interrupt mask register us_imr read-only 0x0 0x0014 channel status register us_csr read-only ? 0x0018 receiver holding register us_rhr read-only 0x0 0x001c transmitter holding register us_thr write-only ? 0x0020 baud rate generator register us_brgr read/write 0x0 0x0024 receiver time-out register us_rtor read/write 0x0 0x0028 transmitter timeguard register us_ttgr read/write 0x0 0x2c - 0x3c reserved ? ? ? 0x0040 fi di ratio register us_fidi read/write 0x174 0x0044 number of errors register us_ner read-only ? 0x0048 reserved ? ? ? 0x004c irda filter register us_if read/write 0x0 0x5c - 0xfc reserved ? ? ? 0x100 - 0x128 reserved for pdc registers ? ? ?
301 6042e?atarm?14-dec-06 at91sam7a3 preliminary 29.6.1 usart control register name: us_cr access type: write-only rstrx: reset receiver 0: no effect. 1: resets the receiver. rsttx: reset transmitter 0: no effect. 1: resets the transmitter. rxen: receiver enable 0: no effect. 1: enables the receiver, if rxdis is 0. rxdis: receiver disable 0: no effect. 1: disables the receiver. txen: transmitter enable 0: no effect. 1: enables the transmitter if txdis is 0. txdis: transmitter disable 0: no effect. 1: disables the transmitter. rststa: reset status bits 0: no effect. 1: resets the status bits pare, frame, ovre, and rxbrk in us_csr. sttbrk: start break 0: no effect. 1: starts transmission of a break after the characters present in us_thr and the transmit shi ft register have been trans- mitted. no effect if a break is already being transmitted. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ????rtsdisrtsen?? 15 14 13 12 11 10 9 8 retto rstnack rstit senda sttto stpbrk sttbrk rststa 76543210 txdis txen rxdis rxen rsttx rstrx ? ?
302 6042e?atarm?14-dec-06 at91sam7a3 preliminary stpbrk: stop break 0: no effect. 1: stops transmission of the break after a minimum of one char acter length and transmits a high level during 12-bit periods. no effect if no break is being transmitted. sttto: start time-out 0: no effect. 1: starts waiting for a character before clocking the time-out counter. resets the status bit timeout in us_csr. senda: send address 0: no effect. 1: in multidrop mode only, the next character written to the us_thr is sent with the address bit set. rstit: reset iterations 0: no effect. 1: resets iteration in us_csr. no e ffect if the iso7816 is not enabled. rstnack: reset non acknowledge 0: no effect 1: resets nack in us_csr. retto: rearm time-out 0: no effect 1: restart time-out rtsen: request to send enable 0: no effect. 1: drives the pin rts to 0. rtsdis: request to send disable 0: no effect. 1: drives the pin rts to 1.
303 6042e?atarm?14-dec-06 at91sam7a3 preliminary 29.6.2 usart mode register name: us_mr access type: read/write usart_mode usclks: clock selection 31 30 29 28 27 26 25 24 ? ? ? filter ? max_iteration 23 22 21 20 19 18 17 16 ? ? dsnack inack over clko mode9 msbf 15 14 13 12 11 10 9 8 chmode nbstop par sync 76543210 chrl usclks usart_mode usart_mode mode of the usart 0000normal 0001rs485 0 0 1 0 hardware handshaking 0011reserved 0 1 0 0 is07816 protocol: t = 0 0101reserved 0 1 1 0 is07816 protocol: t = 1 0111reserved 1000irda 11xxreserved usclks selected clock 00mck 01mck / div 10reserved 11sck
304 6042e?atarm?14-dec-06 at91sam7a3 preliminary chrl: character length. sync: synchronous mode select 0: usart operates in asynchronous mode. 1: usart operates in synchronous mode. par: parity type nbstop: number of stop bits chmode: channel mode msbf: bit order 0: least significant bit is sent/received first. 1: most significant bit is sent/received first. chrl character length 0 0 5 bits 0 1 6 bits 1 0 7 bits 1 1 8 bits par parity type 0 0 0 even parity 001odd parity 0 1 0 parity forced to 0 (space) 0 1 1 parity forced to 1 (mark) 1 0 x no parity 1 1 x multidrop mode nbstop asynchronous (sync = 0) synchronous (sync = 1) 0 0 1 stop bit 1 stop bit 0 1 1.5 stop bits reserved 1 0 2 stop bits 2 stop bits 1 1 reserved reserved chmode mode description 0 0 normal mode 0 1 automatic echo. receiver input is connected to the txd pin. 1 0 local loopback. transmitter output is connected to the receiver input.. 1 1 remote loopback. rxd pin is internally connected to the txd pin.
305 6042e?atarm?14-dec-06 at91sam7a3 preliminary mode9: 9-bit character length 0: chrl defines character length. 1: 9-bit character length. clko: clock output select 0: the usart does not drive the sck pin. 1: the usart drives the sck pin if usclks does not select the external clock sck. over: oversampling mode 0: 16x oversampling. 1: 8x oversampling. inack: inhibit non acknowledge 0: the nack is generated. 1: the nack is not generated. dsnack: disable successive nack 0: nack is sent on the iso line as soon as a parity erro r occurs in the received character (unless inack is set). 1: successive parity errors are counted up to the value spec ified in the max_iteration field. these parity errors gener- ate a nack on the iso line. as soon as this value is reac hed, no additional nack is sent on the iso line. the flag iteration is asserted. max_iteration defines the maximum number of iterations in mode iso7816, protocol t= 0. filter: infrared receive line filter 0: the usart does not filter the receive line. 1: the usart filters the receive line using a three-sample filter (1/16-bit clock) (2 over 3 majority).
306 6042e?atarm?14-dec-06 at91sam7a3 preliminary 29.6.3 usart interrupt enable register name: us_ier access type: write-only rxrdy: rxrdy interrupt enable txrdy: txrdy interrupt enable rxbrk: receiver break interrupt enable endrx: end of receive transfer interrupt enable endtx: end of transmit interrupt enable ovre: overrun error interrupt enable frame: framing error interrupt enable pare: parity error interrupt enable timeout: time-out interrupt enable txempty: txempty interrupt enable iteration: iteration interrupt enable txbufe: buffer empty interrupt enable rxbuff: buffer full interrupt enable nack: non acknowledge interrupt enable ctsic: clear to send input change interrupt enable 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ????ctsic ? ? ? 15 14 13 12 11 10 9 8 ? ? nack rxbuff txbufe iteration txempty timeout 76543210 pare frame ovre endtx endrx rxbrk txrdy rxrdy
307 6042e?atarm?14-dec-06 at91sam7a3 preliminary 29.6.4 usart interrupt disable register name: us_idr access type: write-only rxrdy: rxrdy interrupt disable txrdy: txrdy interrupt disable rxbrk: receiver bre ak interrupt disable endrx: end of receive transfer interrupt disable endtx: end of transmit interrupt disable ovre: overrun error interrupt disable frame: framing error interrupt disable pare: parity error interrupt disable timeout: time-out interrupt disable txempty: txempty interrupt disable iteration: iteration interrupt disable txbufe: buffer empty interrupt disable rxbuff: buffer full interrupt disable nack: non acknowledge interrupt disable ctsic: clear to send input change interrupt disable 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ????ctsic ? ? ? 15 14 13 12 11 10 9 8 ? ? nack rxbuff txbufe iteration txempty timeout 76543210 pare frame ovre endtx endrx rxbrk txrdy rxrdy
308 6042e?atarm?14-dec-06 at91sam7a3 preliminary 29.6.5 usart interrupt mask register name: us_imr access type: read-only rxrdy: rxrdy interrupt mask txrdy: txrdy interrupt mask rxbrk: receiver break interrupt mask endrx: end of receive transfer interrupt mask endtx: end of transmit interrupt mask ovre: overrun error interrupt mask frame: framing error interrupt mask pare: parity error interrupt mask timeout: time-out interrupt mask txempty: txempty interrupt mask iteration: iteration interrupt mask txbufe: buffer empty interrupt mask rxbuff: buffer full interrupt mask nack: non acknowledge interrupt mask ctsic: clear to send input change interrupt mask 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ????ctsic ? ? ? 15 14 13 12 11 10 9 8 ? ? nack rxbuff txbufe iteration txempty timeout 76543210 pare frame ovre endtx endrx rxbrk txrdy rxrdy
309 6042e?atarm?14-dec-06 at91sam7a3 preliminary 29.6.6 usart channel status register name: us_csr access type: read-only rxrdy: receiver ready 0: no complete character has been received since the last read of us_rhr or the receiver is disabled. if characters were being received when the receiver was disabled, rx rdy changes to 1 when the receiver is enabled. 1: at least one complete char acter has been rece ived and us_rhr has not yet been read. txrdy: transmitter ready 0: a character is in the us_thr waiting to be transferred to the transmit shift register, or an sttbrk command has been requested, or the transmitter is disabled. as soon as the transmitter is enabled, txrdy becomes 1. 1: there is no char acter in the us_thr. rxbrk: break received/end of break 0: no break received or end of break detected since the last rststa. 1: break received or end of break detected since the last rststa. endrx: end of receiver transfer 0: the end of transfer signal from the receive pdc channel is inactive. 1: the end of transfer signal from the receive pdc channel is active. endtx: end of transmitter transfer 0: the end of transfer signal from the transmit pdc channel is inactive. 1: the end of transfer signal from the transmit pdc channel is active. ovre: overrun error 0: no overrun error has occurred since the last rststa. 1: at least one overrun error has occurred since the last rststa. frame: framing error 0: no stop bit has been detected low since the last rststa. 1: at least one stop bit has been detected low since the last rststa. pare: parity error 0: no parity error has been detected since the last rststa. 1: at least one parity error has been detected since the last rststa. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 cts ? ? ? ctsic ? ? ? 15 14 13 12 11 10 9 8 ? ? nack rxbuff txbufe iteration txempty timeout 76543210 pare frame ovre endtx endrx rxbrk txrdy rxrdy
310 6042e?atarm?14-dec-06 at91sam7a3 preliminary timeout: receiver time-out 0: there has not been a time-out since t he last start time-out command (sttto in us_cr) or the time-out register is 0. 1: there has been a time-out since the last start time-out command (sttto in us_cr). txempty: transmitter empty 0: there are characters in either us_thr or the tr ansmit shift register, or the transmitter is disabled. 1: there is at least one character in either us_thr or the transmit shift register. iteration: max number of repetitions reached 0: maximum number of repetitions has not been reached since the last rsit. 1: maximum number of repetitions has been reached since the last rsit. txbufe: transmission buffer empty 0: the signal buffer empty from the transmit pdc channel is inactive. 1: the signal buffer empty from the transmit pdc channel is active. rxbuff: reception buffer full 0: the signal buffer full from the receive pdc channel is inactive. 1: the signal buffer full from th e receive pdc channel is active. nack: non acknowledge 0: no non acknowledge has not been detected since the last rstnack. 1: at least one non acknowledge has been detected since the last rstnack. ctsic: clear to send input change flag 0: no input change has been detected on the cts pin since the last read of us_csr. 1: at least one input change has been detected on the cts pin since the last read of us_csr. cts: image of cts input 0: cts is at 0. 1: cts is at 1.
311 6042e?atarm?14-dec-06 at91sam7a3 preliminary 29.6.7 usart receive holding register name: us_rhr access type: read-only rxchr: received character last character received if rxrdy is set. rxsynh: received sync 0: last character received is a data. 1: last character received is a command. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 rxsynh ??????rxchr 76543210 rxchr
312 6042e?atarm?14-dec-06 at91sam7a3 preliminary 29.6.8 usart transmit holding register name: us_thr access type: write-only txchr: character to be transmitted next character to be transmitted after the current character if txrdy is not set. txsynh: sync field to be transmitted 0: the next character sent is encoded as a data. start frame delimiter is data sync. 1: the next character sent is encoded as a command. start frame delimiter is command sync. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 txsynh ??????txchr 76543210 txchr
313 6042e?atarm?14-dec-06 at91sam7a3 preliminary 29.6.9 usart baud rate generator register name: us_brgr access type: read/write cd: clock divider 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ????? ? 15 14 13 12 11 10 9 8 cd 76543210 cd cd usart_mode iso7816 usart_mode = iso7816 sync = 0 sync = 1 over = 0 over = 1 0 baud rate clock disabled 1 to 65535 baud rate = selected clock/16/cd baud rate = selected clock/8/cd baud rate = selected clock /cd baud rate = selected clock/cd/fi_di_ratio
314 6042e?atarm?14-dec-06 at91sam7a3 preliminary 29.6.10 usart receiver time-out register name: us_rtor access type: read/write to: time-out value 0: the receiver time-out is disabled. 1 - 65535: the receiver time-out is enabled and the time-out delay is to x bit period. 29.6.11 usart transmitter timeguard register name: us_ttgr access type: read/write tg: timeguard value 0: the transmitter timeguard is disabled. 1 - 255: the transmitter timeguard is enabled and the timeguard delay is tg x bit period. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 to 76543210 to 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ???????? 76543210 tg
315 6042e?atarm?14-dec-06 at91sam7a3 preliminary 29.6.12 usart fi di ratio register name: us_fidi access type: read/write reset value : 0x174 fi_di_ratio: fi over di ratio value 0: if iso7816 mode is selected, the baud rate generator generates no signal. 1 - 2047: if iso7816 mode is selected, the baud rate is the clock provided on sck divided by fi_di_ratio. 29.6.13 usart number of errors register name: us_ner access type: read-only nb_errors: number of errors total number of errors that occurred during an iso7816 transfer. this register automatically clears when read. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ????? fi_di_ratio 76543210 fi_di_ratio 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ???????? 76543210 nb_errors
316 6042e?atarm?14-dec-06 at91sam7a3 preliminary 29.6.14 usart irda filter register name: us_if access type: read/write irda_filter: irda filter sets the filter of the irda demodulator. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ???????? 76543210 irda_filter
317 6042e?atarm?14-dec-06 at91sam7a3 preliminary 30. synchronous serial controller (ssc) 30.1 overview the atmel synchronous serial controller (ssc) provides a synchronous communication link with external devices. it supports many serial synchronous communication protocols generally used in audio and telecom applications such as i2s, short frame sync, long frame sync, etc. the ssc contains an independent receiver and transmitter and a common clock divider. the receiver and the transmitter each interface with three signals: the td/rd signal for data, the tk/rk signal for the clock and the tf/rf signal for the frame sync. the transfers can be pro- grammed to start automatically or on different events detected on the frame sync signal. the ssc?s high-level of progra mmability and its two dedicated pdc channels of up to 32 bits permit a continuous high bit rate data transfer without processor intervention. featuring connection to two pdc channels, the ssc permits interfacing with low processor overhead to the following: codec?s in master or slave mode dac through dedicated serial interface, particularly i2s magnetic card reader
318 6042e?atarm?14-dec-06 at91sam7a3 preliminary 30.2 block diagram figure 30-1. block diagram 30.3 application block diagram figure 30-2. application block diagram ssc interface pio pdc apb bridge mck asb apb tf tk td rf rk rd interrupt control ssc interrupt pmc interrupt management power management test management ssc serial audio os or rtos driver codec frame management line interface time slot management
319 6042e?atarm?14-dec-06 at91sam7a3 preliminary 30.4 pin name list 30.5 product dependencies 30.5.1 i/o lines the pins used for interfacing the compliant ex ternal devices may be multiplexed with pio lines. before using the ssc receiver, the pio controller must be configured to dedicate the ssc receiver i/o lines to the ssc peripheral mode. before using the ssc transmitter, the pio contro ller must be configured to dedicate the ssc transmitter i/o lines to the ssc peripheral mode. 30.5.2 power management the ssc is not continuously clocked. the ssc interface may be clocked through the power management controller (pmc), therefore the programmer must first configure the pmc to enable the ssc clock. 30.5.3 interrupt the ssc interface has an interrupt line connected to the advanced interrupt controller (aic). handling interrupts requires programming the aic before configuring the ssc. all ssc interrupts can be enabled/disabled conf iguring the ssc interrupt mask register. each pending and unmasked ssc interr upt will assert the ssc interrupt line. th e ssc interrupt ser- vice routine can get the interrupt origin by reading the ssc interrupt status register. 30.6 functional description this chapter contains the functional description of the following: ssc functional block, clock management, data format, start, transmitter, receiver and frame sync. the receiver and transmitter operate separately. however, they can work synchronously by programming the receiver to use the transmit cloc k and/or to start a data transfer when trans- mission starts. alternatively, this can be done by programming the transmitter to use the receive clock and/or to start a data transfer when reception starts. the transmitter and the receiver can be programmed to operate with the clo ck signals provided on either the tk or rk pins. this allows the ssc to support many slave-mode data transfers. the maximum clock speed allowed on the tk and rk pins is the master clock divided by 2. table 30-1. i/o lines description pin name pin description type rf receiver frame synchro input/output rk receiver clock input/output rd receiver data input tf transmitter frame synchro input/output tk transmitter clock input/output td transmitter data output
320 6042e?atarm?14-dec-06 at91sam7a3 preliminary figure 30-3. ssc functional block diagram 30.6.1 clock management the transmitter clock can be generated by: an external clock received on the tk i/o pad the receiver clock the internal clock divider the receiver clock can be generated by: an external clock received on the rk i/o pad the transmitter clock the internal clock divider furthermore, the transmitter block can generate an external clock on the tk i/o pad, and the receiver block can generate an external clock on the rk i/o pad. this allows the ssc to support many master and slave mode data transfers. interrupt control aic user interface apb mck receive clock controller start selector tx clock rk input rf tf clock output controller frame sync controller transmit clock controller transmit shift register start selector transmit sync holding register transmit holding register load shift rx clock tx clock tk input tf tx pdc rf rd rf rk clock output controller frame sync controller receive shift register receive sync holding register receive holding register load shift td tf tk rx clock rx pdc receiver pdc transmitter clock divider
321 6042e?atarm?14-dec-06 at91sam7a3 preliminary 30.6.1.1 clock divider figure 30-4. divided clock block diagram the master clock divider is determined by the 12-bit field div counter and comparator (so its maximal value is 4095) in the clock mode regi ster ssc_cmr, allowing a master clock divi- sion by up to 8190. the divided clock is provided to both the receiver and transmitter. when this field is programmed to 0, the clock divider is not used an d remains inactive. when div is set to a value equal to or greater than 1, the divided clock has a frequency of master clock divided by 2 times div. each level of the divided clock has a duration of the master clock multiplied by div. this ensures a 50% duty cycle for the divided clock regard- less of whether the div value is even or odd. figure 30-5. divided clock generation 30.6.1.2 transmitter clock management the transmitter clock is generated from the receiv er clock or the divider clock or an external clock scanned on the tk i/o pad. the transmitte r clock is selected by the cks field in ssc_tcmr (transmit clock mode register). transmit clock can be inverted independently by the cki bits in ssc_tcmr. the transmitter can also drive the tk i/o pad continuously or be limited to the actual data transfer. the clock output is configured by the ssc_tcmr register. the transmit clock inver- maximum minimum mck / 2 mck / 8190 mck divided clock clock divider / 2 12-bit counter ssc_cmr master clock divided clock div = 1 master clock divided clock div = 3 divided clock frequency = mck/2 divided clock frequency = mck/6
322 6042e?atarm?14-dec-06 at91sam7a3 preliminary sion (cki) bits have no effect on the clock outputs. programming the tcmr register to select tk pin (cks field) and at the same time contin uous transmit clock (cko field) might lead to unpredictable results. figure 30-6. transmitter clock management 30.6.1.3 receiver clock management the receiver clock is generated from the transmitter clock or the divider clock or an external clock scanned on the rk i/o pad. the receive clock is selected by the cks field in ssc_rcmr (receive clock mode register). receive clocks can be inverted independently by the cki bits in ssc_rcmr. the receiver can also drive the rk i/o pad continuously or be limited to the actual data trans- fer. the clock output is configured by the ss c_rcmr register. the receive clock inversion (cki) bits have no effect on the clock outputs. programming the rcmr register to select rk pin (cks field) and at the same time continuous receive clock (cko field) can lead to unpre- dictable results. tk (pin) receiver clock divider clock cks cko data transfer cki ckg transmitter clock clock output mux tri_state controller tri-state controller inv mux
323 6042e?atarm?14-dec-06 at91sam7a3 preliminary figure 30-7. receiver clock management 30.6.1.4 serial clock ratio considerations the transmitter and the receiver can be programmed to operate with the clock signals pro- vided on either the tk or rk pins. this allo ws the ssc to support many slave-mode data transfers. in this case, the maximum clock speed allowed on the rk pin is: ? master clock divided by 2 if receiver frame synchro is input ? master clock divided by 3 if receiver frame synchro is output in addition, the maximum clock s peed allowed on the tk pin is: ? master clock divided by 6 if transmit frame synchro is input ? master clock divided by 2 if transmit frame synchro is output 30.6.2 transmitter operations a transmitted frame is triggered by a start even t and can be followed by synchronization data before data transmission. the start event is configured by setting the transmit clock mode register (ssc_tcmr). see ?start? on page 325. the frame synchronization is configured setting the transmit frame mode register (ssc_tfmr). see ?frame sync? on page 327. to transmit data, the transmitter uses a shift register clocked by the transmitter clock signal and the start mode selected in the ssc_tcmr. data is written by the application to the ssc_thr register then transferred to the shift register according to the data format selected. when both the ssc_thr and the transmit shift register are empty, the status flag txempty is set in ssc_sr. when the transmit holding regi ster is transferred in the transmit shift reg- ister, the status flag txrdy is set in ssc_sr and additional data can be loaded in the holding register. rk (pin) transmitter clock divider clock cks cko data transfer cki ckg receiver clock clock output mux tri-state controller tri-state controller inv mux
324 6042e?atarm?14-dec-06 at91sam7a3 preliminary figure 30-8. transmitter block diagram 30.6.3 receiver operations a received frame is triggered by a start event and can be followed by synchronization data before data transmission. the start event is configured setting the receive clock mode register (ssc_rcmr). see ?start? on page 325. the frame synchronization is configured setting the receive frame mode register (ssc_rfmr). see ?frame sync? on page 327. the receiver uses a shift register clocked by the receiver clock signal and the start mode selected in the ssc_rcmr. the data is transferred from the shift register depending on the data format selected. when the receiver shift register is full, the ssc transfers this data in the holding register, the status flag rxrdy is set in ssc_sr and the data can be read in the receiver holding register. if another transfer occurs before read of the rh r register, the status flag overun is set in ssc_sr and the receiver shift register is transferred in the rhr register. transmit shift register start selector ssc_tshr ssc_thr transmitter clock td ssc_tfmr.fslen ssc_tfmr.datlen ssc_cr.txen ssc_cr.txdis ssc_tcmr.sttdly ssc_tfmr.fsden ssc_tfmr.datnb ssc_sr.txen ssc_tfmr.datdef ssc_tfmr.msbf ssc_tcmr.sttdly ssc_tfmr.fsden 0 1 1 0 rf tf
325 6042e?atarm?14-dec-06 at91sam7a3 preliminary figure 30-9. receiver block diagram 30.6.4 start the transmitter and receiver can both be programmed to start their operations when an event occurs, respectively in the transmit start se lection (start) field of ssc_tcmr and in the receive start selection (start) field of ssc_rcmr. under the following conditions the start event is independently programmable: continuous. in this case, the transmission starts as soon as a word is written in ssc_thr and the reception starts as soon as the receiver is enabled. synchronously with the transmitter/receiver on detection of a falling/rising edge on tf/rf on detection of a low level/high level on tf/rf on detection of a level change or an edge on tf/rf a start can be programmed in the same manner on either side of the transmit/receive clock register (rcmr/tcmr). thus, the start coul d be on tf (transmit) or rf (receive). moreover, the receiver can start when data is detected in the bit stream with the compare functions. detection on tf/rf input/output is done by the field fsos of the transmit/receive frame mode register (tfmr/rfmr). receive shift register start selector ssc_rhr ssc_rshr receiver clock rd ssc_rfmr.fslen ssc_rfmr.datlen rf ssc_cr.rxen ssc_cr.rxdis ssc_sr.rxen ssc_rfmr.msbf ssc_rcmr.sttdly ssc_rfmr.datnb tf
326 6042e?atarm?14-dec-06 at91sam7a3 preliminary figure 30-10. transmit start mode figure 30-11. receive pulse/ed ge start modes x tk tf (input) td (output) td (output) td (output) td (output) td (output) td (output) xbob1 x bo b1 bo b1 bo b1 bo b1 bo b1 bo b1 b1 bo x x x sttdly sttdly sttdly sttdly sttdly sttdly start = falling edge on tf start = rising edge on tf start = low level on tf start = high level on tf start = any edge on tf start = level change on tf x rk rf (input) rd (input) rd (input) rd (input) rd (input) rd (input) rd (input) xbob1 x bo b1 bo b1 bo b1 bo b1 bo b1 bo b1 b1 bo x x x sttdly sttdly sttdly sttdly sttdly sttdly start = falling edge on rf start = rising edge on rf start = low level on rf start = high level on rf start = any edge on rf start = level change on rf
327 6042e?atarm?14-dec-06 at91sam7a3 preliminary 30.6.5 frame sync the transmitter and receiver frame sync pins, tf and rf, can be programmed to generate different kinds of frame synchronization signals. the frame sync output selection (fsos) field in the receive frame mode register (ssc_rfmr) and in the transmit frame mode register (ssc_tfmr) are used to select the required waveform. programmable low or high levels during data transfer are supported. programmable high levels before the start of data transfers or toggling are also supported. if a pulse waveform is selected, the frame sync length (fslen) field in ssc_rfmr and ssc_tfmr programs the length of the pulse, from 1 bit time up to 16 bit time. the periodicity of the receive and transmit frame sync pulse output can be programmed through the period divider selection ( period) field in ssc_rcmr and ssc_tcmr. 30.6.5.1 frame sync data frame sync data transmits or receives a specific tag during the frame sync signal. during the frame sync signal, the receiver can sample the rd line and store the data in the receive sync holding register and the transmit ter can transfer transmit sync holding regis- ter in the shifter register. the data length to be sampled/shifted out during the frame sync signal is programmed by the fslen field in ssc_rfmr/ssc_tfmr. concerning the receive frame sync data operation, if the frame sync length is equal to or lower than the delay between the start event and the actual data reception, the data sampling operation is performed in the receive sync holding register through the receive shift register. the transmit frame sync operation is performed by the transmitter only if the bit frame sync data enable (fsden) in ssc_tfmr is set. if the frame sync length is equal to or lower than the delay between the start event and the actual data transmission, the normal transmission has priority and the data contained in the transmit sync holding register is transferred in the transmit register, then shifted out. 30.6.5.2 frame sync edge detection the frame sync edge detection is programmed by the fsedge field in ssc_rfmr/ssc_tfmr. this sets the corres ponding flags rxsyn/txsyn in the ssc sta- tus register (ssc_sr) on frame synchro edge detection (signals rf/tf). 30.6.6 receive compare modes figure 30-12. receive compare modes cmp0 cmp3 cmp2 cmp1 ignored b0 b2 b1 start rk rd (input) fslen up to 16 bits (4 in this example) stdly datlen
328 6042e?atarm?14-dec-06 at91sam7a3 preliminary 30.6.6.1 compare functions compare 0 can be one start event of the receiver. in this case, the receiver compares at each new sample the last fslen bits received at t he fslen lower bit of the data contained in the compare 0 register (ssc_rc0r). when this start event is selected, the user can program the receiver to start a new data transfer either by writing a new compare 0, or by receiving continuously until compare 1 occurs. this se lection is done with the bit (stop) in ssc_rcmr. 30.6.7 data format the data framing format of both the transmitter and the receiver are programmable through the transmitter frame mode register (ssc_tfmr) and the receiver frame mode register (ssc_rfmr). in either case, the user can independently select: the event that starts the data transfer (start) the delay in number of bit periods between the start event and the first data bit ( sttdly ) the length of the data (datlen) the number of data to be transferred for each start event (datnb). the length of synchronization transferred for each start event (fslen) the bit sense: most or lowest significant bit first (msbf). additionally, the transmitter can be used to transfer synchronization and select the level driven on the td pin while not in data transfer operati on. this is done respectively by the frame sync data enable (fsden) and by the data default value (datdef) bits in ssc_tfmr.
329 6042e?atarm?14-dec-06 at91sam7a3 preliminary figure 30-13. transmit and receive frame format in edge/pulse start modes note: 1. example of input on falling edge of tf/rf. table 30-2. data frame registers transmitter receiver field length comment ssc_tfmr ssc_rfmr datlen up to 32 size of word ssc_tfmr ssc_rfmr datnb up to 16 number of words transmitted in frame ssc_tfmr ssc_rfmr msbf most significant bit first ssc_tfmr ssc_rfmr fslen up to 16 size of synchro data register ssc_tfmr datdef 0 or 1 data default value ended ssc_tfmr fsden enable send ssc_tshr ssc_tcmr ssc_rcmr period up to 512 frame size ssc_tcmr ssc_rcmr sttdly up to 255 size of transmit start delay sync data default sttdly sync data ignored rd default data datlen data data data datlen data data default default ignored sync data sync data fslen tf/rf (1) start start from ssc_tshr from ssc_thr from ssc_thr from ssc_thr from ssc_thr to ssc_rhr to ssc_rhr to ssc_rshr td (if fsden = 0) td (if fsden = 1) datnb period fromdatdef fromdatdef from datdef from datdef
330 6042e?atarm?14-dec-06 at91sam7a3 preliminary figure 30-14. transmit frame format in continuous mode note: 1. sttdly is set to 0. in this example, ssc_thr is loaded twice. fsden value has no effect on the transmission. syncdata cannot be output in continuous mode. figure 30-15. receive frame format in continuous mode note: 1. sttdly is set to 0. 30.6.8 loop mode the receiver can be programmed to receive transmissions from the transmitter. this is done by setting the loop mode (loop) bit in ssc_rfm r. in this case, rd is connected to td, rf is connected to tf and rk is connected to tk. 30.6.9 interrupt most bits in ssc_sr have a corresponding bit in interrupt management registers. the ssc can be programmed to generate an interrupt when it detects an event. the interrupt is controlled by writing ssc_ier (interrupt enable register) and ssc_idr (interrupt disable register) these registers enable and disable, re spectively, the corresponding interrupt by set- ting and clearing the corresponding bit in ssc_im r (interrupt mask register), which controls the generation of interrupts by asserting the ssc interrupt line connected to the aic. datlen data datlen data default start from ssc_thr from ssc_thr td start: 1. txempty set to 1 2. write into the ssc_thr data datlen data datlen start = enable receiver to ssc_rhr to ssc_rhr rd
331 6042e?atarm?14-dec-06 at91sam7a3 preliminary figure 30-16. interrupt block diagram ssc_imr pdc interrupt control ssc interrupt set rxrdy ovrun rxsync receiver transmitter txrdy txempty txsync txbufe endtx rxbuff endrx clear ssc_ier ssc_idr
332 6042e?atarm?14-dec-06 at91sam7a3 preliminary 30.7 ssc application examples the ssc can support several serial communicati on modes used in audio or high speed serial links. some standard applications are shown in th e following figures. all se rial link applications supported by the ssc are not listed here. figure 30-17. audio application block diagram figure 30-18. codec application block diagram ssc rk rf rd td tf tk clock sck word select ws data sd i2s receiver clock sck word select ws data sd right channel left channel msb msb lsb ssc rk rf rd td tf tk serial data clock (sclk) frame sync (fsync) serial data out serial data in codec serial data clock (sclk) frame sync (fsync) serial data out serial data in first time slot dstart dend
333 6042e?atarm?14-dec-06 at91sam7a3 preliminary figure 30-19. time slot application block diagram ssc rk rf rd td tf tk sclk fsync data out data in codec first time slot serial data clock (sclk) frame sync (fsync) serial data out serial data in codec second time slot first time slot second time slot dstart dend
334 6042e?atarm?14-dec-06 at91sam7a3 preliminary 30.8 synchronous serial contro ller (ssc) user interface table 30-3. register mapping offset register register name access reset 0x0 control register ssc_cr write ? 0x4 clock mode register ssc_cmr read/write 0x0 0x8 reserved ? ? ? 0xc reserved ? ? ? 0x10 receive clock mode register ssc_rcmr read/write 0x0 0x14 receive frame mode register ssc_rfmr read/write 0x0 0x18 transmit clock mode register ssc_tcmr read/write 0x0 0x1c transmit frame mode register ssc_tfmr read/write 0x0 0x20 receive holding register ssc_rhr read 0x0 0x24 transmit holding register ssc_thr write ? 0x28 reserved ? ? ? 0x2c reserved ? ? ? 0x30 receive sync. holding register ssc_rshr read 0x0 0x34 transmit sync. holding register ssc_tshr read/write 0x0 0x38 receive compare 0 register ssc_rc0r read/write 0x0 0x3c receive compare 1 register ssc_rc1r read/write 0x0 0x40 status register ssc_sr read 0x000000cc 0x44 interrupt enable register ssc_ier write ? 0x48 interrupt disable register ssc_idr write ? 0x4c interrupt mask register ssc_imr read 0x0 0x50-0xfc reserved ? ? ? 0x100- 0x124 reserved for peripheral data controller (pdc) ? ? ?
335 6042e?atarm?14-dec-06 at91sam7a3 preliminary 30.8.1 ssc control register name: ssc_cr access type: write-only rxen: receive enable 0: no effect. 1: enables receive if rxdis is not set. rxdis: receive disable 0: no effect. 1: disables receive. if a character is currently being re ceived, disables at end of current character reception. txen: transmit enable 0: no effect. 1: enables transmit if txdis is not set. txdis: transmit disable 0: no effect. 1: disables transmit. if a character is currently being transmitted, disables at end of current character transmission. swrst: software reset 0: no effect. 1: performs a software reset. has priority on any other bit in ssc_cr. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 swrst?????txdistxen 76543210 ??????rxdisrxen
336 6042e?atarm?14-dec-06 at91sam7a3 preliminary 30.8.2 ssc clock mode register name: ssc_cmr access type: read/write div: clock divider 0: the clock divider is not active. any other value: the divided clock equals the master clock divided by 2 times div. the maximum bit rate is mck/2. the minimum bit rate is mck/2 x 4095 = mck/8190. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ???? div 76543210 div
337 6042e?atarm?14-dec-06 at91sam7a3 preliminary 30.8.3 ssc receive clock mode register name: ssc_rcmr access type: read/write cks: receive clock selection cko: receive clock output mode selection cki: receive clock inversion 0: the data inputs (data and frame sync signals) are sample d on receive clock falling edge . the frame sync signal out- put is shifted out on receive clock rising edge. 1: the data inputs (data and frame sync signals) are sample d on receive clock rising edge. the frame sync signal out- put is shifted out on receive clock falling edge. cki affects only the receive clock and not the output clock signal. 31 30 29 28 27 26 25 24 period 23 22 21 20 19 18 17 16 stddly 15 14 13 12 11 10 9 8 ? ? ? stop start 76543210 ckg cki cko cks cks selected receive clock 0x0 divided clock 0x1 tk clock signal 0x2 rk pin 0x3 reserved cko receive clock output mode rk pin 0x0 none input-only 0x1 continuous receive clock output 0x2 receive clock only during data transfers output 0x3-0x7 reserved
338 6042e?atarm?14-dec-06 at91sam7a3 preliminary ckg: receive clock gating selection start: receive start selection stop: receive stop selection 0: after completion of a data transfer when starting with a compare 0, the receiver stops the data transfer and waits for a new compare 0. 1: after starting a receive with a compare 0, the receiver operates in a continuous mode until a compare 1 is detected. sttdly: receive start delay if sttdly is not 0, a delay of sttdly clock cycles is inserted between the start event and the actual start of reception. when the receiver is programmed to start synchronously with the transmitter, the delay is also applied. note: it is very important that sttdly be set carefully. if sttdly must be set, it should be done in relation to tag (receive sync data) reception. period: receive period divider selection this field selects the divider to apply to the selected receive clock in order to generate a new frame sync signal. if 0, no period signal is generated. if not 0, a period sig nal is generated each 2 x (period+1) receive clock. ckg receive clock gating 0x0 none, continuous clock 0x1 receive clock enabled only if rf low 0x2 receive clock enabled only if rf high 0x3 reserved start receive start 0x0 continuous, as soon as the receiver is enabled, and imme diately after the end of transfer of the previous data. 0x1 transmit start 0x2 detection of a low level on rf signal 0x3 detection of a high level on rf signal 0x4 detection of a falling edge on rf signal 0x5 detection of a rising edge on rf signal 0x6 detection of any level change on rf signal 0x7 detection of any edge on rf signal 0x8 compare 0 0x9-0xf reserved
339 6042e?atarm?14-dec-06 at91sam7a3 preliminary 30.8.4 ssc receive frame mode register name: ssc_rfmr access type: read/write datlen: data length 0: forbidden value (1-bit data length not supported). any other value: the bit stream contains datlen + 1 data bits. moreover, it defines the transfer size performed by the pdc2 assigned to the receiver. if datlen is lower or equal to 7, data transfers are in bytes. if datlen is between 8 and 15 (included), half-words are transferred, and for any other value, 32-bit words are transferred. loop: loop mode 0: normal operating mode. 1: rd is driven by td, rf is driven by tf and tk drives rk. msbf: most significant bit first 0: the lowest significant bit of the data register is sampled first in the bit stream. 1: the most significant bit of the data register is sampled first in the bit stream. datnb: data number per frame this field defines the number of data words to be received after each transfer start, which is equal to (datnb + 1). fslen: receive frame sync length this field defines the length of the receive frame sync signal and the number of bits sampled and stored in the receive sync data register. when this mode is selected by the start field in the receive clock mode register, it also deter- mines the length of the sampled data to be compared to the compare 0 or compare 1 register. pulse length is equal to (fslen + 1) receive clock periods. th us, if fslen is 0, the receive frame sync signal is gener- ated during one receive clock period. 31 30 29 28 27 26 25 24 ???????fsedge 23 22 21 20 19 18 17 16 ? fsos fslen 15 14 13 12 11 10 9 8 ???? datnb 76543210 msbf ? loop datlen
340 6042e?atarm?14-dec-06 at91sam7a3 preliminary fsos: receive frame sync output selection fsedge: frame sync edge detection determines which edge on frame sy nc will generate the in terrupt rxsyn in the ssc status register. fsos selected receive frame sync signal rf pin 0x0 none input-only 0x1 negative pulse output 0x2 positive pulse output 0x3 driven low during data transfer output 0x4 driven high during data transfer output 0x5 toggling at each start of data transfer output 0x6-0x7 reserved undefined fsedge frame sync edge detection 0x0 positive edge detection 0x1 negative edge detection
341 6042e?atarm?14-dec-06 at91sam7a3 preliminary 30.8.5 ssc transmit clock mode register name: ssc_tcmr access type: read/write cks: transmit clock selection cko: transmit clock output mode selection cki: transmit clock inversion 0: the data outpu ts (data and frame sync signals) are shifted out on tr ansmit clock falling edge . the frame sync signal input is sampled on transmit clock rising edge. 1: the data outputs (data and frame sync signals) are shifted out on transmit clock rising edge. the frame sync signal input is sampled on tran smit clock falling edge. cki affects only the transmit clock and not the output clock signal. ckg: transmit clock gating selection 31 30 29 28 27 26 25 24 period 23 22 21 20 19 18 17 16 sttdly 15 14 13 12 11 10 9 8 ???? start 76543210 ckg cki cko cks cks selected transmit clock 0x0 divided clock 0x1 rk clock signal 0x2 tk pin 0x3 reserved cko transmit clock output mode tk pin 0x0 none input-only 0x1 continuous transmit clock output 0x2 transmit clock only during data transfers output 0x3-0x7 reserved ckg transmit clock gating 0x0 none, continuous clock 0x1 transmit clock enabled only if tf low 0x2 transmit clock enabled only if tf high 0x3 reserved
342 6042e?atarm?14-dec-06 at91sam7a3 preliminary start: transmit start selection sttdly: transmit start delay if sttdly is not 0, a delay of sttdly clock cycles is insert ed between the start event and the actual start of transmission of data. when the transmitter is programmed to start sync hronously with the receiver, the delay is also applied. note: sttdly must be set carefully. if sttdly is too short in respect to tag (transmit sync data) emission, data is emit- ted instead of the end of tag. period: transmit period divider selection this field selects the divider to apply to the selected transmi t clock to generate a new frame sync signal. if 0, no period signal is generated. if not 0, a period signal is generated at each 2 x (period+1) transmit clock. start transmit start 0x0 continuous, as soon as a word is written in the ssc_thr register (if transmit is enabled), and immediately after the end of transfer of the previous data. 0x1 receive start 0x2 detection of a low level on tf signal 0x3 detection of a high level on tf signal 0x4 detection of a falling edge on tf signal 0x5 detection of a rising edge on tf signal 0x6 detection of any level change on tf signal 0x7 detection of any edge on tf signal 0x8 - 0xf reserved
343 6042e?atarm?14-dec-06 at91sam7a3 preliminary 30.8.6 ssc transmit frame mode register name: ssc_tfmr access type: read/write datlen: data length 0: forbidden value (1-bit data length not supported). any other value: the bit stream contains datlen + 1 data bits. moreover, it defines the transfer size performed by the pdc2 assigned to the transmit. if datlen is lower or equal to 7, data transfers are bytes, if datlen is between 8 and 15 (included), half-words are transferred, and for any other value, 32-bit words are transferred. datdef: data default value this bit defines the level driven on the td pin while out of tran smission. note that if the pin is defined as multi-drive by th e pio controller, the pin is enabled only if the scc td output is 1. msbf: most significant bit first 0: the lowest significant bit of the data register is shifted out first in the bit stream. 1: the most significant bit of the data register is shifted out first in the bit stream. datnb: data number per frame this field defines the number of data words to be transferred after each transfer start, which is equal to (datnb +1). fslen: transmit frame sync length this field defines the length of the transmit frame sync signal and the number of bits shifted out from the transmit sync data register if fsden is 1. pulse length is equal to (fslen + 1) transmit clock periods, i.e., the pulse length can range from 1 to 16 transmit clock periods. if fslen is 0, the transmit frame sync signal is generated during one transmit clock period. 31 30 29 28 27 26 25 24 ???????fsedge 23 22 21 20 19 18 17 16 fsden fsos fslen 15 14 13 12 11 10 9 8 ???? datnb 76543210 m s b f ? dat d e f dat l e n
344 6042e?atarm?14-dec-06 at91sam7a3 preliminary fsos: transmit frame sync output selection fsden: frame sync data enable 0: the td line is driven with the default va lue during the transmi t frame sync signal. 1: ssc_tshr value is shifted out during the tran smission of the transmit frame sync signal. fsedge: frame sync edge detection determines which edge on frame sync will gene rate the interrupt tx syn (status register). fsos selected transmit frame sync signal tf pin 0x0 none input-only 0x1 negative pulse output 0x2 positive pulse output 0x3 driven low during data transfer output 0x4 driven high during data transfer output 0x5 toggling at each start of data transfer output 0x6-0x7 reserved undefined fsedge frame sync edge detection 0x0 positive edge detection 0x1 negative edge detection
345 6042e?atarm?14-dec-06 at91sam7a3 preliminary 30.8.7 ssc receive holding register name: ssc_rhr access type: read-only rdat: receive data right aligned regardless of the number of data bits defined by datlen in ssc_rfmr. 30.8.8 ssc transmit holding register name: ssc_thr access type: write-only tdat: transmit data right aligned regardless of the number of data bits defined by datlen in ssc_tfmr. 31 30 29 28 27 26 25 24 rdat 23 22 21 20 19 18 17 16 rdat 15 14 13 12 11 10 9 8 rdat 76543210 rdat 31 30 29 28 27 26 25 24 tdat 23 22 21 20 19 18 17 16 tdat 15 14 13 12 11 10 9 8 tdat 76543210 tdat
346 6042e?atarm?14-dec-06 at91sam7a3 preliminary 30.8.9 ssc receive synchronization holding register name: ssc_rshr access type: read-only rsdat: receive synchronization data 30.8.10 ssc transmit synchronization holding register name: ssc_tshr access type: read/write tsdat: transmit synchronization data 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 rsdat 76543210 rsdat 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 tsdat 76543210 tsdat
347 6042e?atarm?14-dec-06 at91sam7a3 preliminary 30.8.11 ssc receive compare 0 register name: ssc_rc0r access type: read/write cp0: receive compare data 0 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 cp0 76543210 cp0
348 6042e?atarm?14-dec-06 at91sam7a3 preliminary 30.8.12 ssc receive compare 1 register name: ssc_rc1r access type: read/write cp1: receive compare data 1 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 cp1 76543210 cp1
349 6042e?atarm?14-dec-06 at91sam7a3 preliminary 30.8.13 ssc status register name: ssc_sr access type: read-only txrdy: transmit ready 0: data has been loaded in ssc_thr and is waiting to be loaded in the transmit shift register (tsr). 1: ssc_thr is empty. txempty: transmit empty 0: data remains in ssc_thr or is currently transmitted from tsr. 1: last data written in ssc_thr has been loaded in tsr and last data loaded in tsr has been transmitted. endtx: end of transmission 0: the register ssc_tcr has not reached 0 since the last write in ssc_tcr or ssc_tncr. 1: the register ssc_tcr has reached 0 sinc e the last write in ssc_tcr or ssc_tncr. txbufe: transmit buffer empty 0: ssc_tcr or ssc_tncr have a value other than 0. 1: both ssc_tcr and ssc_tncr have a value of 0. rxrdy: receive ready 0: ssc_rhr is empty. 1: data has been received and loaded in ssc_rhr. ovrun: receive overrun 0: no data has been loaded in ssc_rhr wh ile previous data has not been read since the last read of the status register. 1: data has been loaded in ssc_rhr while previous data has not yet been read since the last read of the status register. endrx: end of reception 0: data is written on the receive counter register or receive ne xt counter register. 1: end of pdc transfer when receive counter register has arrived at zero. rxbuff: receive buffer full 0: ssc_rcr or ssc_rncr have a value other than 0. 1: both ssc_rcr and ssc_rncr have a value of 0. cp0: compare 0 0: a compare 0 has not occurred since the last read of the status register. 1: a compare 0 has occurred since the last read of the status register. cp1: compare 1 0: a compare 1 has not occurred since the last read of the status register. 1: a compare 1 has occurred since the last read of the status register. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ??????rxentxen 15 14 13 12 11 10 9 8 ????rxsynt xsyn cp1 cp0 76543210 rxbuff endrx ovrun rxrdy txbufe endtx txempty txrdy
350 6042e?atarm?14-dec-06 at91sam7a3 preliminary txsyn: transmit sync 0: a tx sync has not occurred since the last read of the status register. 1: a tx sync has occurred since the last read of the status register. rxsyn: receive sync 0: an rx sync has not occurred since the last read of the status register. 1: an rx sync has occurred since the last read of the status register. txen: transmit enable 0: transmit is disabled. 1: transmit is enabled. rxen: receive enable 0: receive is disabled. 1: receive is enabled.
351 6042e?atarm?14-dec-06 at91sam7a3 preliminary 30.8.14 ssc interrupt enable register name: ssc_ier access type: write-only txrdy: transmit ready interrupt enable 0: no effect. 1: enables the transmit ready interrupt. txempty: transmit empty interrupt enable 0: no effect. 1: enables the transmit empty interrupt. endtx: end of transmission interrupt enable 0: no effect. 1: enables the end of transmission interrupt. txbufe: transmit buffer empty interrupt enable 0: no effect. 1: enables the transmit buffer empty interrupt rxrdy: receive ready interrupt enable 0: no effect. 1: enables the receive ready interrupt. ovrun: receive overrun interrupt enable 0: no effect. 1: enables the receive overrun interrupt. endrx: end of reception interrupt enable 0: no effect. 1: enables the end of reception interrupt. rxbuff: receive buffer full interrupt enable 0: no effect. 1: enables the receive buffer full interrupt. cp0: compare 0 interrupt enable 0: no effect. 1: enables the compare 0 interrupt. cp1: compare 1 interrupt enable 0: no effect. 1: enables the compare 1 interrupt. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ????rxsynt xsyn cp1 cp0 76543210 rxbuff endrx ovrun rxrdy txbufe endtx txempty txrdy
352 6042e?atarm?14-dec-06 at91sam7a3 preliminary txsyn: tx sync interrupt enable 0: no effect. 1: enables the tx sync interrupt. rxsyn: rx sync interrupt enable 0: no effect. 1: enables the rx sync interrupt.
353 6042e?atarm?14-dec-06 at91sam7a3 preliminary 30.8.15 ssc interrupt disable register name: ssc_idr access type: write-only txrdy: transmit ready interrupt disable 0: no effect. 1: disables the transmit ready interrupt. txempty: transmit empty interrupt disable 0: no effect. 1: disables the transmit empty interrupt. endtx: end of transmission interrupt disable 0: no effect. 1: disables the end of transmission interrupt. txbufe: transmit buffer empty interrupt disable 0: no effect. 1: disables the transmit buffer empty interrupt. rxrdy: receive ready interrupt disable 0: no effect. 1: disables the rece ive ready interrupt. ovrun: receive overrun interrupt disable 0: no effect. 1: disables the receive overrun interrupt. endrx: end of reception interrupt disable 0: no effect. 1: disables the end of reception interrupt. rxbuff: receive buffer full interrupt disable 0: no effect. 1: disables the receiv e buffer full interrupt. cp0: compare 0 interrupt disable 0: no effect. 1: disables the compare 0 interrupt. cp1: compare 1 interrupt disable 0: no effect. 1: disables the compare 1 interrupt. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ????rxsynt xsyn cp1 cp0 76543210 rxbuff endrx ovrun rxrdy txbufe endtx txempty txrdy
354 6042e?atarm?14-dec-06 at91sam7a3 preliminary txsyn: tx sync interrupt enable 0: no effect. 1: disables the tx sync interrupt. rxsyn: rx sync interrupt enable 0: no effect. 1: disables the rx sync interrupt.
355 6042e?atarm?14-dec-06 at91sam7a3 preliminary 30.8.16 ssc interrupt mask register name: ssc_imr access type: read-only txrdy: transmit ready interrupt mask 0: the transmit ready interrupt is disabled. 1: the transmit ready interrupt is enabled. txempty: transmit empty interrupt mask 0: the transmit empty interrupt is disabled. 1: the transmit empty interrupt is enabled. endtx: end of transmission interrupt mask 0: the end of transmission interrupt is disabled. 1: the end of transmission interrupt is enabled. txbufe: transmit buffer empty interrupt mask 0: the transmit buffer empty interrupt is disabled. 1: the transmit buffer empty interrupt is enabled. rxrdy: receive ready interrupt mask 0: the receive ready interrupt is disabled. 1: the receive ready interrupt is enabled. ovrun: receive overrun interrupt mask 0: the receive overrun interrupt is disabled. 1: the receive overrun interrupt is enabled. endrx: end of reception interrupt mask 0: the end of reception interrupt is disabled. 1: the end of reception interrupt is enabled. rxbuff: receive buffer full interrupt mask 0: the receive buffer full interrupt is disabled. 1: the receive buffer full interrupt is enabled. cp0: compare 0 interrupt mask 0: the compare 0 interrupt is disabled. 1: the compare 0 interrupt is enabled. cp1: compare 1 interrupt mask 0: the compare 1 interrupt is disabled. 1: the compare 1 interrupt is enabled. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ????rxsynt xsyn cp1 cp0 76543210 rxbuf endrx ovrun rxrdy txbufe endtx txempty txrdy
356 6042e?atarm?14-dec-06 at91sam7a3 preliminary txsyn: tx sync interrupt mask 0: the tx sync interrupt is disabled. 1: the tx sync interrupt is enabled. rxsyn: rx sync interrupt mask 0: the rx sync interrupt is disabled. 1: the rx sync interrupt is enabled.
357 6042e?atarm?14-dec-06 at91sam7a3 preliminary 31. timer/counter (tc) 31.1 overview the timer counter (tc) includes three identical 16-bit timer counter channels. each channel can be independently programmed to perform a wide range of functions includ- ing frequency measurement, event counting, interval measurem ent, pulse generation, delay timing and pulse width modulation. each channel has three external clock inputs, fi ve internal clock inputs and two multi-purpose input/output signals which can be configured by the user. each channel drives an internal interrupt signal which can be programmed to generate processor interrupts. the timer counter block has two global registers which act upon all three tc channels. the block control register allows the three ch annels to be started simultaneously with the same instruction. the block mode register defines the external clock inputs for each channel, allowing them to be chained. table 31-1 gives the assignment of the device timer counter clock inputs common to timer counter 0 to 2. table 31-1. timer counter clock assignment name definition timer_clock1 mck/2 timer_clock2 mck/8 timer_clock3 mck/32 timer_clock4 mck/128 timer_clock5 mck/1024
358 6042e?atarm?14-dec-06 at91sam7a3 preliminary 31.2 block diagram figure 31-1. timer/counter block diagram table 31-2. signal name description block/channel signal name description channel signal xc0, xc1, xc2 external clock inputs tioa capture mode: timer/counter input waveform mode: timer/counter output tiob capture mode: timer/counter input waveform mode: timer/counter input/output int interrupt signal output sync synchronization input signal timer/counter channel 0 timer/counter channel 1 timer/counter channel 2 sync parallel i/o controller tc1xc1s tc0xc0s tc2xc2s int0 int1 int2 tioa0 tioa1 tioa2 tiob0 tiob1 tiob2 xc0 xc1 xc2 xc0 xc1 xc2 xc0 xc1 xc2 tclk0 tclk1 tclk2 tclk0 tclk1 tclk2 tclk0 tclk1 tclk2 tioa1 tioa2 tioa0 tioa2 tioa0 tioa1 advanced interrupt controller tclk0 tclk1 tclk2 tioa0 tiob0 tioa1 tiob1 tioa2 tiob2 timer counter tioa tiob tioa tiob tioa tiob sync sync timer_clock2 timer_clock3 timer_clock4 timer_clock5 timer_clock1
359 6042e?atarm?14-dec-06 at91sam7a3 preliminary 31.3 pin name list 31.4 product dependencies 31.4.1 i/o lines the pins used for interfacing the compliant ex ternal devices may be multiplexed with pio lines. the programmer must first program the pio controllers to assign the tc pins to their peripheral functions. 31.4.2 power management the tc is clocked through the power management controller (pmc), thus the programmer must first configure the pmc to enable the timer/counter clock. 31.4.3 interrupt the tc has an interrupt line connected to the advanced interrupt controller (aic). handling the tc interrupt requires programming the aic before configuring the tc. table 31-3. tc pin list pin name description type tclk0-tclk2 external clock input input tioa0-tioa2 i/o line a i/o tiob0-tiob2 i/o line b i/o
360 6042e?atarm?14-dec-06 at91sam7a3 preliminary 31.5 functional description 31.5.1 tc description the three channels of the timer/counter are independent and identical in operation. the reg- isters for channel programming are listed in table 31-5 on page 373 . 31.5.1.1 16-bit counter each channel is organized around a 16-bit counter. the value of the counter is incremented at each positive edge of the selected clock. when the counter has reached the value 0xffff and passes to 0x0000, an overflow occurs and th e covfs bit in tc_sr (status register) is set. the current value of the counter is accessible in real time by reading the counter value regis- ter, tc_cv. the counter can be reset by a trigger . in this case, the counter value passes to 0x0000 on the next valid edge of the selected clock. 31.5.1.2 clock selection at block level, input clock signals of each channel can either be connected to the external inputs tclk0, tclk1 or tclk2, or be connect ed to the configurable in ternal signals tioa0, tioa1 or tioa2 for chaining by programming the tc_bmr (block mode). see figure 31-2 . each channel can independently select an internal or external clock source for its counter: internal clock signals: timer_cl ock1, timer_clock2, timer_clock3, timer_clock4, timer_clock5 external clock signals: xc0, xc1 or xc2 this selection is made by the tcclks bits in the tc channel mode register. the selected clock can be inverted with the clki bit in tc_cmr. this allows counting on the opposite edges of the clock. the burst function allows the clock to be vali dated when an external signal is high. the burst parameter in the mode register defines this signal (none, xc0, xc1, xc2). see fig- ure 31-3 note: in all cases, if an external clock is used, the duration of each of its levels must be longer than the master clock period. the external clock frequency must be at least 2.5 times lower than the master clock
361 6042e?atarm?14-dec-06 at91sam7a3 preliminary figure 31-2. clock chaining selection figure 31-3. clock selection timer/counter channel 0 sync tc0xc0s tioa0 tiob0 xc0 xc1 = tclk1 xc2 = tclk2 tclk0 tioa1 tioa2 timer/counter channel 1 sync tc1xc1s tioa1 tiob1 xc0 = tclk2 xc1 xc2 = tclk2 tclk1 tioa0 tioa2 timer/counter channel 2 sync tc2xc2s tioa2 tiob2 xc0 = tclk0 xc1 = tclk1 xc2 tclk2 tioa0 tioa1 timer_clock1 timer_clock2 timer_clock3 timer_clock4 timer_clock5 xc0 xc1 xc2 tcclks clki burst 1 selected clock
362 6042e?atarm?14-dec-06 at91sam7a3 preliminary 31.5.1.3 clock control the clock of each counter can be controlled in two different ways: it can be enabled/disabled and started/stopped. see figure 31-4 . the clock can be enabled or disabled by the user with the clken and the clkdis commands in the control register. in capture mode it can be disabled by an rb load event if ldbdis is set to 1 in tc_cmr. in waveform mode, it can be disabled by an rc compare event if cpcdis is set to 1 in tc_cmr. when disabled, the start or the stop actions have no effect: only a clken command in the control register can re-enable the clock. when the clock is enabled, the clksta bit is set in the status register. the clock can also be started or stopped: a trigger (software, synchro, external or compare) always starts the clock. the clock can be stopped by an rb load event in capture mode (ldbstop = 1 in tc_cmr) or a rc compare event in waveform mode (cpcstop = 1 in tc_cmr). the start and the stop commands have effect only if the clock is enabled. figure 31-4. clock control 31.5.1.4 tc operating modes each channel can independently operate in two different modes: capture mode provides measurement on signals. waveform mode provides wave generation. the tc operating mode is programmed with the wave bit in the tc channel mode register. in capture mode, tioa and tiob are configured as inputs. in waveform mode, tioa is always configured to be an output and tiob is an output if it is not selected to be the external trigger. 31.5.1.5 trigger a trigger resets the counter and starts the coun ter clock. three types of triggers are common to both modes, and a fourth external trigger is available to each mode. qs r s r q clksta clken clkdis stop event disable event counter clock selected clock trigger
363 6042e?atarm?14-dec-06 at91sam7a3 preliminary the following triggers are common to both modes: software trigger: each channel has a software trigger, available by setting swtrg in tc_ccr. sync: each channel has a synchronization signal sync. when asserted, this signal has the same effect as a software trigger. the sync signals of all channels are asserted simultaneously by writing tc_bcr (block control) with sync set. compare rc trigger: rc is implemented in each channel and can provide a trigger when the counter value matches the rc valu e if cpctrg is set in tc_cmr. the channel can also be configured to have an external trigger. in capture mode, the external trigger signal can be selected between tioa and tiob. in waveform mode, an external event can be programmed on one of the following signal s: tiob, xc0, xc1 or xc2. this external event can then be programmed to perform a trigger by setting enetrg in tc_cmr. if an external trigger is used, the duration of the pulses must be longer than the master clock period in order to be detected. regardless of the trigger used, it will be taken in to account at the followin g active edge of the selected clock. this means that the counter value can be read differently from zero just after a trigger, especially when a low frequency signal is selected as the clock. 31.5.2 capture operating mode this mode is entered by cleari ng the wave parameter in tc_cmr (channel mode register). capture mode allows the tc channel to perf orm measurements such as pulse timing, fre- quency, period, duty cycle and phase on tioa and tiob signals which are considered as inputs. figure 31-5 shows the configuration of the tc channel when programmed in capture mode. 31.5.2.1 capture registers a and b registers a and b (ra and rb) are used as captur e registers. this means that they can be loaded with the counter value when a programmable event occurs on the signal tioa. the ldra parameter in tc_cmr defines the tioa edge for the loading of register a, and the ldrb parameter defines the tioa edge for the loading of register b. ra is loaded only if it has not been loaded since the last trigger or if rb has been loaded since the last loading of ra. rb is loaded only if ra has been loaded sinc e the last trigger or t he last loading of rb. loading ra or rb before the read of the last value loaded sets the overrun error flag (lovrs) in tc_sr (status register). in this case, the old value is overwritten. 31.5.2.2 trigger conditions in addition to the sync signal, the software trigger and the rc compare trigger, an external trigger can be defined. the abetrg bit in tc_cmr select s tioa or tiob input signal as an external trigger. the etrgedg parameter defines the e dge (rising, falling or both) de tected to gene rate an exter- nal trigger. if etrgedg = 0 (none), the external trigger is disabled.
364 6042e?atarm?14-dec-06 at91sam7a3 preliminary figure 31-5. capture mode timer_clock1 timer_clock2 timer_clock3 timer_clock4 timer_clock5 xc0 xc1 xc2 tcclks clki qs r s r q clksta clken clkdis burst tiob register c capture register a capture register b compare rc = 16-bit counter abetrg swtrg etrgedg cpctrg tc1_imr trig ldrbs ldras etrgs tc1_sr lovrs covfs sync 1 mtiob tioa mtioa ldra ldbstop if ra is not loaded or rb is loaded if ra is loaded ldbdis cpcs int edge detector edge detector ldrb edge detector clk ovf reset timer/counter channel
365 6042e?atarm?14-dec-06 at91sam7a3 preliminary 31.5.3 waveform operating mode waveform operating mode is entered by setting the wave par ameter in tc_cmr (channel mode register). in waveform operating mode the tc channel generates 1 or 2 pwm signals with the same frequency and independently programmable duty cycles , or generates different types of one- shot or repetitive pulses. in this mode, tioa is configured as an output and tiob is defined as an output if it is not used as an external event ( eevt parameter in tc_cmr). figure 31-6 shows the configuration of the tc channel when programmed in waveform oper- ating mode. 31.5.3.1 waveform selection depending on the wavsel parameter in tc_cmr (channel mode register), the behavior of tc_cv varies. with any selection, ra, rb and rc can all be used as compare registers. ra compare is used to control the tioa output, rb compare is used to control the tiob out- put (if correctly configured) and rc compare is used to control tioa and/or tiob outputs.
366 6042e?atarm?14-dec-06 at91sam7a3 preliminary figure 31-6. waveform mode tcclks clki qs r s r q clksta clken clkdis cpcdis burst tiob register a register b register c compare ra = compare rb = compare rc = cpcstop 16-bit counter eevt eevtedg sync swtrg enetrg wavsel tc1_imr trig acpc acpa aeevt aswtrg bcpc bcpb beevt bswtrg tioa mtioa tiob mtiob cpas covfs etrgs tc1_sr cpcs cpbs clk ovf reset output controller output controller int 1 edge detector timer/counter channel timer_clock1 timer_clock2 timer_clock3 timer_clock4 timer_clock5 xc0 xc1 xc2 wavsel
367 6042e?atarm?14-dec-06 at91sam7a3 preliminary 31.5.3.2 wavsel = 00 when wavsel = 00, the value of tc_cv is in cremented from 0 to 0xffff. once 0xffff has been reached, the value of tc_cv is reset. incrementation of tc_cv starts again and the cycle continues. see figure 31-7 . an external event trigger or a software trigger can reset the value of tc_cv. it is important to note that the trigger may occur at any time. see figure 31-8 . rc compare cannot be programmed to generate a trigger in this configuration. at the same time, rc compare can stop the counter clock (cpcstop = 1 in tc_cmr) and/or disable the counter clock (cpcdis = 1 in tc_cmr). figure 31-7. wavsel= 00 without trigger time counter value r c r b r a tiob tioa counter cleared by compare match with 0xffff 0xffff waveform examples
368 6042e?atarm?14-dec-06 at91sam7a3 preliminary figure 31-8. wavsel= 00 with trigger 31.5.3.3 wavsel = 10 when wavsel = 10, the value of tc_cv is increm ented from 0 to the value of rc, then auto- matically reset on a rc compare. once the value of tc_cv has been reset, it is then incremented and so on. see figure 31-9 . it is important to note that tc_cv can be reset at any time by an external event or a software trigger if both are programmed correctly. see figure 31-10 . in addition, rc compare can stop the counte r clock (cpcstop = 1 in tc_cmr) and/or dis- able the counter clock (cpcdis = 1 in tc_cmr). time counter value r c r b r a tiob tioa counter cleared by compare match with 0xffff 0xffff waveform examples counter cleared by trigger
369 6042e?atarm?14-dec-06 at91sam7a3 preliminary figure 31-9. wavsel = 10 without trigger figure 31-10. wavsel = 10 with trigger 31.5.3.4 wavsel = 01 when wavsel = 01, the value of tc_cv is incremented from 0 to 0xffff. once 0xffff is reached, the value of tc_cv is decremented to 0, then re-incremented to 0xffff and so on. see figure 31-11 . a trigger such as an external event or a software trigger can modify tc_cv at any time. if a trigger occurs while tc_cv is incrementing, tc_cv then decrements. if a trigger is received while tc_cv is decrementing, tc_cv then increments. see figure 31-12 . time counter value r c r b r a tiob tioa counter cleared by compare match with rc 0xffff waveform examples time counter value r c r b r a tiob tioa counter cleared by compare match with rc 0xffff waveform examples counter cleared by trigger
370 6042e?atarm?14-dec-06 at91sam7a3 preliminary rc compare cannot be programmed to generate a trigger in this configuration. at the same time, rc compare can stop the counter clock (cpcstop = 1) and/or disable the counter clock (cpcdis = 1). figure 31-11. wavsel = 01 without trigger figure 31-12. wavsel = 01 with trigger 31.5.3.5 wavsel = 11 when wavsel = 11, the value of tc_cv is incremented from 0 to rc. once rc is reached, the value of tc_cv is decremented to 0, then re-incremented to rc and so on. see figure 31-13 . time counter value r c r b r a tiob tioa counter decremented by compare match with 0xffff 0xffff waveform examples time counter value tiob tioa counter decremented by compare match with 0xffff 0xffff waveform examples counter decremented by trigger counter incremented by trigger r c r b r a
371 6042e?atarm?14-dec-06 at91sam7a3 preliminary a trigger such as an external event or a software trigger can modify tc_cv at any time. if a trigger occurs while tc_cv is incrementing, tc_cv then decrements. if a trigger is received while tc_cv is decrementing, tc_cv then increments. see figure 31-14 . rc compare can stop the counter clock (cpcstop = 1) and/or disable the counter clock (cpcdis = 1). figure 31-13. wavsel = 11 without trigger figure 31-14. wavsel = 11 with trigger time counter value r c r b r a tiob tioa counter decremented by compare match with rc 0xffff waveform examples time counter value tiob tioa counter decremented by compare match with rc 0xffff waveform examples counter decremented by trigger counter incremented by trigger r c r b r a
372 6042e?atarm?14-dec-06 at91sam7a3 preliminary 31.5.4 external event/trigger conditions an external event can be programmed to be det ected on one of the clock sources (xc0, xc1, xc2) or tiob. the external event selected can then be used as a trigger. the eevt parameter in tc_cmr selects the external trigger. the eevtedg parameter defines the trigger edge for each of the possibl e external triggers (rising, falling or both). if eevtedg is cleared (none), no external event is defined. if tiob is defined as an external event signal (eevt = 0), tiob is no longer used as an output and the compare register b is not used to generate waveforms and subsequently no irqs. in this case the tc channel can only generate a waveform on tioa. when an external event is defined, it can be used as a trigger by setting bit enetrg in tc_cmr. as in capture mode, the sync signal and the softw are trigger are also available as triggers. rc compare can also be used as a tr igger depending on the parameter wavsel. 31.5.5 output controller the output controller defines the output level changes on tioa and tiob following an event. tiob control is used only if tiob is defin ed as output (not as an external event). the following events control tioa and tiob: so ftware trigger, external event and rc com- pare. ra compare controls tioa and rb comp are controls tiob. each of these events can be programmed to set, clear or toggle the output as defined in the corresponding parameter in tc_cmr.
373 6042e?atarm?14-dec-06 at91sam7a3 preliminary 31.6 timer/counter (tc) user interface 31.6.1 global register mapping tc_bcr (block control register) and tc_bmr (block mode register) control the whole tc block. tc channels are controlled by the registers listed in table 31-5 . the offset of each of the channel registers in table 31-5 is in relation to the offset of the corresponding channel as men - tioned in table 31-5 . 31.6.2 channel memory mapping notes: 1. read-only if wave = 0 table 31-4. timer/counter (tc) global register map offset channel/register name access reset value 0x00 tc channel 0 see table 31-5 0x40 tc channel 1 see table 31-5 0x80 tc channel 2 see table 31-5 0xc0 tc block control register tc_bcr write-only ? 0xc4 tc block mode register tc_bmr read/write 0 table 31-5. tc channel memory map offset register name access reset value 0x00 channel control register tc_ccr write-only ? 0x04 channel mode register tc_cmr read/write 0 0x08 reserved ? 0x0c reserved ? 0x10 counter value tc_cv read-only 0 0x14 register a tc_ra read/write (1) 0 0x18 register b tc_rb read/write (1) 0 0x1c register c tc_rc read/write 0 0x20 status register tc_sr read-only 0 0x24 interrupt enable register tc_ier write-only ? 0x28 interrupt disable register tc_idr write-only ? 0x2c interrupt mask register tc_imr read-only 0 0xfc reserved ? ? ?
374 6042e?atarm?14-dec-06 at91sam7a3 preliminary 31.6.3 tc block control register register name: tc_bcr access type: write-only sync: synchro command 0 = no effect. 1 = asserts the sync signal which generates a software trigger simultaneously for each of the channels. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ???????? 76543210 ???????sync
375 6042e?atarm?14-dec-06 at91sam7a3 preliminary 31.6.4 tc block mode register register name: tc_bmr access type: read/write tc0xc0s: external clock signal 0 selection tc1xc1s: external clock signal 1 selection tc2xc2s: external clock signal 2 selection 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ???????? 76543210 ? ? tc2xc2s tcxc1s tc0xc0s tc0xc0s signal connected to xc0 00tclk0 0 1 none 10tioa1 11tioa2 tc1xc1s signal connected to xc1 00tclk1 0 1 none 10tioa0 11tioa2 tc2xc2s signal connected to xc2 00tclk2 0 1 none 10tioa0 11tioa1
376 6042e?atarm?14-dec-06 at91sam7a3 preliminary 31.6.5 tc channel control register register name: tc_ccr access type: write-only clken: counter clock enable command 0 = no effect. 1 = enables the clock if clkdis is not 1. clkdis: counter clock disable command 0 = no effect. 1 = disables the clock. swtrg: software trigger command 0 = no effect. 1 = a software trigger is performed: the counter is reset and the clock is started. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ???????? 76543210 ?????swtrgclkdisclken
377 6042e?atarm?14-dec-06 at91sam7a3 preliminary 31.6.6 tc channel mode register: capture mode register name: tc_cmr access type: read/write tcclks: clock selection clki: clock invert 0 = counter is incremented on rising edge of the clock. 1 = counter is incremented on falling edge of the clock. burst: burst signal selection ldbstop: counter clock stopped with rb loading 0 = counter clock is not stopped when rb loading occurs. 1 = counter clock is stopped when rb loading occurs. ldbdis: counter clock disable with rb loading 0 = counter clock is not disabl ed when rb loading occurs. 1 = counter clock is disabled when rb loading occurs. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ? ? ? ? ldrb ldra 15 14 13 12 11 10 9 8 wave = 0 cpctrg ? ? ? abetrg etrgedg 76543210 ldbdis ldbstop burst clki tcclks tcclks clock selected 000timer_clock1 001timer_clock2 010timer_clock3 011timer_clock4 100timer_clock5 101xc0 110xc1 111xc2 burst 0 0 the clock is not gated by an external signal. 0 1 xc0 is anded with the selected clock. 1 0 xc1 is anded with the selected clock. 1 1 xc2 is anded with the selected clock.
378 6042e?atarm?14-dec-06 at91sam7a3 preliminary etrgedg: external trigger edge selection abetrg: tioa or tiob external trigger selection 0 = tiob is used as an external trigger. 1 = tioa is used as an external trigger. cpctrg: rc compare trigger enable 0 = rc compare has no effect on the counter and its clock. 1 = rc compare resets the counter and starts the counter clock. wave 0 = capture mode is enabled. 1 = capture mode is disabled (waveform mode is enabled). ldra: ra loading selection ldrb: rb loading selection etrgedg edge 0 0 none 0 1 rising edge 1 0 falling edge 1 1 each edge ldra edge 0 0 none 0 1 rising edge of tioa 1 0 falling edge of tioa 1 1 each edge of tioa ldrb edge 0 0 none 0 1 rising edge of tioa 1 0 falling edge of tioa 1 1 each edge of tioa
379 6042e?atarm?14-dec-06 at91sam7a3 preliminary 31.6.7 tc channel mode register: waveform mode register name: tc_cmr access type: read/write tcclks: clock selection clki: clock invert 0 = counter is incremented on rising edge of the clock. 1 = counter is incremented on falling edge of the clock. burst: burst signal selection cpcstop: counter clock stopped with rc compare 0 = counter clock is not stopped when counter reaches rc. 1 = counter clock is stopped when counter reaches rc. cpcdis: counter clock disable with rc compare 0 = counter clock is not disabl ed when counter reaches rc. 1 = counter clock is disabled when counter reaches rc. 31 30 29 28 27 26 25 24 bswtrg beevt bcpc bcpb 23 22 21 20 19 18 17 16 aswtrg aeevt acpc acpa 15 14 13 12 11 10 9 8 wave = 1 wavsel enetrg eevt eevtedg 76543210 cpcdis cpcstop burst clki tcclks tcclks clock selected 0 0 0 timer_clock1 0 0 1 timer_clock2 0 1 0 timer_clock3 0 1 1 timer_clock4 1 0 0 timer_clock5 101xc0 110xc1 111xc2 burst 0 0 the clock is not gated by an external signal. 0 1 xc0 is anded with the selected clock. 1 0 xc1 is anded with the selected clock. 1 1 xc2 is anded with the selected clock.
380 6042e?atarm?14-dec-06 at91sam7a3 preliminary eevtedg: external ev ent edge selection eevt: external event selection note: 1. if tiob is chosen as the external event signal, it is conf igured as an input and no longer generates waveforms and subse- quently no irqs . enetrg: external event trigger enable 0 = the external event has no effect on the counter and its clock. in this case, the selected external event only controls the tioa output. 1 = the external event resets the counter and starts the counter clock. wavsel: waveform selection wave = 1 0 = waveform mode is disabled (capture mode is enabled). 1 = waveform mode is enabled. acpa: ra compare effect on tioa eevtedg edge 0 0 none 0 1 rising edge 1 0 falling edge 1 1 each edge eevt signal selected as exte rnal event tiob direction 0 0 tiob input (1) 01xc0 output 10xc1 output 11xc2 output wavsel effect 0 0 up mode without automatic trigger on rc compare 1 0 up mode with automa tic trigger on rc compare 0 1 updown mode without automatic trigger on rc compare 1 1 updown mode with automatic trigger on rc compare acpa effect 0 0 none 0 1 set 1 0 clear 1 1 toggle
381 6042e?atarm?14-dec-06 at91sam7a3 preliminary acpc: rc compare effect on tioa aeevt: external event effect on tioa aswtrg: software trigger effect on tioa bcpb: rb compare effect on tiob bcpc: rc compare effect on tiob acpc effect 0 0 none 0 1 set 1 0 clear 1 1 toggle aeevt effect 0 0 none 0 1 set 1 0 clear 1 1 toggle aswtrg effect 0 0 none 0 1 set 1 0 clear 1 1 toggle bcpb effect 0 0 none 0 1 set 1 0 clear 1 1 toggle bcpc effect 0 0 none 0 1 set 1 0 clear 1 1 toggle
382 6042e?atarm?14-dec-06 at91sam7a3 preliminary beevt: external event effect on tiob bswtrg: software trigger effect on tiob beevt effect 0 0 none 0 1 set 1 0 clear 1 1 toggle bswtrg effect 0 0 none 0 1 set 1 0 clear 1 1 toggle
383 6042e?atarm?14-dec-06 at91sam7a3 preliminary 31.6.8 tc counter value register register name: tc_cv access type: read-only cv: counter value cv contains the counter value in real time. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 cv 76543210 cv
384 6042e?atarm?14-dec-06 at91sam7a3 preliminary 31.6.9 tc register a register name: tc_ra access type: read-only if wave = 0, read/write if wave = 1 ra: register a ra contains the register a value in real time. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ra 76543210 ra
385 6042e?atarm?14-dec-06 at91sam7a3 preliminary 31.6.10 tc register b register name: tc_rb access type: read-only if wave = 0, read/write if wave = 1 rb: register b rb contains the register b value in real time. 31.6.11 tc register c register name: tc_rc access type: read/write rc: register c rc contains the register c value in real time. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 rb 76543210 rb 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 rc 76543210 rc
386 6042e?atarm?14-dec-06 at91sam7a3 preliminary 31.6.12 tc status register register name: tc_sr access type: read-only covfs: counter overflow status 0 = no counter overflow has occurred since the last read of the status register. 1 = a counter overflow has occurred since the last read of the status register. lovrs: load overrun status 0 = load overrun has not occurred since the last read of the status register or wave = 1. 1 = ra or rb have been loaded at least twice without any read of the corresponding register since the last read of the sta- tus register, if wave = 0. cpas: ra compare status 0 = ra compare has not occurred since the last read of the status register or wave = 0. 1 = ra compare has occurred since the last read of the status register, if wave = 1. cpbs: rb compare status 0 = rb compare has not occurred since the last read of the status register or wave = 0. 1 = rb compare has occurred since the last read of the status register, if wave = 1. cpcs: rc compare status 0 = rc compare has not occurred since the last read of the status register. 1 = rc compare has occurred since the last read of the status register. ldras: ra loading status 0 = ra load has not occurred si nce the last read of the status register or wave = 1. 1 = ra load has occurred since the last re ad of the status register, if wave = 0. ldrbs: rb loading status 0 = rb load has not occurred si nce the last read of the status register or wave = 1. 1 = rb load has occurred since the last re ad of the status register, if wave = 0. etrgs: external trigger status 0 = external trigger has not occurred since the last read of the status register. 1 = external trigger has occurred since the last read of the status register. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ?????mtiobmtioaclksta 15 14 13 12 11 10 9 8 ???????? 76543210 etrgs ldrbs ldras cpcs cpbs cpas lovrs covfs
387 6042e?atarm?14-dec-06 at91sam7a3 preliminary clksta: clock enabling status 0 = clock is disabled. 1 = clock is enabled. mtioa: tioa mirror 0 = tioa is low. if wave = 0, this mean s that tioa pin is low. if wave = 1, this means that tioa is driven low. 1 = tioa is high. if wave = 0, this mean s that tioa pin is high. if wave = 1, this means that ti oa is driven high. mtiob: tiob mirror 0 = tiob is low. if wave = 0, this mean s that tiob pin is low. if wave = 1, this means that tiob is driven low. 1 = tiob is high. if wave = 0, this mean s that tiob pin is high. if wave = 1, this means that ti ob is driven high.
388 6042e?atarm?14-dec-06 at91sam7a3 preliminary 31.6.13 tc interrupt enable register register name: tc_ier access type: write-only covfs: counter overflow 0 = no effect. 1 = enables the counter overflow interrupt. lovrs: load overrun 0 = no effect. 1 = enables the load overrun interrupt. cpas: ra compare 0 = no effect. 1 = enables the ra compare interrupt. cpbs: rb compare 0 = no effect. 1 = enables the rb compare interrupt. cpcs: rc compare 0 = no effect. 1 = enables the rc compare interrupt. ldras: ra loading 0 = no effect. 1 = enables the ra load interrupt. ldrbs: rb loading 0 = no effect. 1 = enables the rb load interrupt. etrgs: external trigger 0 = no effect. 1 = enables the external trigger interrupt. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ???????? 76543210 etrgs ldrbs ldras cpcs cpbs cpas lovrs covfs
389 6042e?atarm?14-dec-06 at91sam7a3 preliminary 31.6.14 tc interrupt disable register register name: tc_idr access type: write-only covfs: counter overflow 0 = no effect. 1 = disables the counter overflow interrupt. lovrs: load overrun 0 = no effect. 1 = disables the load overru n interrupt (if wave = 0). cpas: ra compare 0 = no effect. 1 = disables the ra compare interrupt (if wave = 1). cpbs: rb compare 0 = no effect. 1 = disables the rb compare interrupt (if wave = 1). cpcs: rc compare 0 = no effect. 1 = disables the rc compare interrupt. ldras: ra loading 0 = no effect. 1 = disables the ra load interrupt (if wave = 0). ldrbs: rb loading 0 = no effect. 1 = disables the rb load interrupt (if wave = 0). etrgs: external trigger 0 = no effect. 1 = disables the external trigger interrupt. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ???????? 76543210 etrgs ldrbs ldras cpcs cpbs cpas lovrs covfs
390 6042e?atarm?14-dec-06 at91sam7a3 preliminary 31.6.15 tc interrupt mask register register name: tc_imr access type: read-only covfs: counter overflow 0 = the counter overflow interrupt is disabled. 1 = the counter overflow interrupt is enabled. lovrs: load overrun 0 = the load overrun interrupt is disabled. 1 = the load overrun interrupt is enabled. cpas: ra compare 0 = the ra compare interrupt is disabled. 1 = the ra compare interrupt is enabled. cpbs: rb compare 0 = the rb compare interrupt is disabled. 1 = the rb compare interrupt is enabled. cpcs: rc compare 0 = the rc compare interrupt is disabled. 1 = the rc compare interrupt is enabled. ldras: ra loading 0 = the load ra interrupt is disabled. 1 = the load ra interrupt is enabled. ldrbs: rb loading 0 = the load rb interrupt is disabled. 1 = the load rb interrupt is enabled. etrgs: external trigger 0 = the external trigger interrupt is disabled. 1 = the external trigger interrupt is enabled. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ???????? 76543210 etrgs ldrbs ldras cpcs cpbs cpas lovrs covfs
391 6042e?atarm?14-dec-06 at91sam7a3 preliminary 32. pulse width modulation controller (pwm) 32.1 overview the pwm macrocell controls several channel s independently. each channel controls one square output waveform. characteristics of the output waveform such as period, duty-cycle and polarity are configurable through the user interface. each channel selects and uses one of the clocks provided by the clock generator. the clock generator provides several clocks result- ing from the division of the pwm macrocell master clock. all pwm macrocell accesses are made through apb mapped registers. channels can be synchronized, to generate non overlapped waveforms. all channels integrate a double buffering system in order to prevent an unexpected output waveform while modifying the period or the duty-cycle. 32.2 block diagram figure 32-1. pulse width modulation controller block diagram pwm controller apb pwmx pwmx pwmx channel update duty cycle counter pwm0 channel pio aic pmc mck clock generator apb interface interrupt generator clock selector period comparator update duty cycle counter clock selector period comparator pwm0 pwm0
392 6042e?atarm?14-dec-06 at91sam7a3 preliminary 32.3 i/o lines description each channel outputs one waveform on one external i/o line. 32.4 product dependencies 32.4.1 i/o lines the pins used for interfacing the pwm may be multiplexed with pio lines. the programmer must first program the pio controller to assign the desired pwm pins to their peripheral func- tion. if i/o lines of the pwm are not used by the application, they can be used for other purposes by the pio controller. all of the pwm outputs may or may not be enabled. if an application requires only four chan- nels, then only four pio lines will be assigned to pwm outputs. 32.4.2 power management the pwm is not continuously clocked. the programmer must first enable the pwm clock in the power management controller (pmc) before using the pwm. however, if the application does not require pwm operations, the pwm clock can be stopped when not needed and be restarted later. in this ca se, the pwm will resume its oper ations where it left off. configuring the pwm does not require the pwm clock to be enabled. 32.4.3 interrupt sources the pwm interrupt line is connected on one of the internal sources of the advanced interrupt controller. using the pwm interrupt requires the aic to be programmed first. note that it is not recommended to use the pwm interrupt line in edge sensitive mode. 32.5 functional description the pwm macrocell is primarily composed of a clock generator module and 8 channels. ? clocked by the system clock, mck, the clock generator module provides 13 clocks. ? each channel can independently choose one of the clock generator outputs. ? each channel generates an output waveform with attributes that can be defined independently for each channel through the user interface registers. table 32-1. i/o line description name description type pwmx pwm waveform output for channel x output
393 6042e?atarm?14-dec-06 at91sam7a3 preliminary 32.5.1 pwm clock generator figure 32-2. functional view of the clock generator block diagram caution: before using the pwm macrocell, the pr ogrammer must first enable the pwm clock in the power management controller (pmc). the pwm macrocell master clock, mck, is divided in the clock generator module to provide different clocks available for all channels. each channel can independently select one of the divided clocks. the clock generator is divided in three blocks: ? a modulo n counter which provides 11 clocks: f mck , f mck /2, f mck /4, f mck /8, f mck /16, f mck /32, f mck /64, f mck /128, f mck /256, f mck /512, f mck /1024 ? two linear dividers (1, 1/2, 1/3, ... 1/255) that provide two separate clocks: clka and clkb each linear divider can independen tly divide one of the clocks of the modulo n counter. the selection of the clock to be divided is made a ccording to the prea (preb) field of the pwm mode register (pwm_mr). the resulting clock cl ka (clkb) is the clock selected divided by diva (divb) field value in the pwm mode register (pwm_mr). after a reset of the pwm cont roller, diva (divb) and prea (p reb) in the pwm mode regis- ter are set to 0. this implies that after reset clka (clkb) are turned off. modulo n counter mck mck/2 mck/4 mck/16 mck/32 mck/64 mck/8 divider a clka diva pwm_mr mck mck/128 mck/256 mck/512 mck/1024 prea divider b clkb divb pwm_mr preb
394 6042e?atarm?14-dec-06 at91sam7a3 preliminary at reset, all clocks provided by the modulo n coun ter are turned off except clock ?clk?. this sit- uation is also true when the pwm master clock is turned off through the power management controller. 32.5.2 pwm channel 32.5.2.1 block diagram figure 32-3. functional view of the channel block diagram each of the 8 channels is composed of three blocks: a clock selector which selects one of the cloc ks provided by the clock generator described in section 32.5.1 ?pwm clock generator? on page 393 . an internal counter clocked by the output of the clock selector. this internal counter is incremented or decremented according to the channel configuration and comparators events. the size of the internal counter is 20 bits. a comparator used to generate events according to the internal counter value. it also computes the pwmx output waveform according to the configuration. 32.5.2.2 waveform properties the different properties of output waveforms are: the internal clock selection . the internal channel counter is clocked by one of the clocks provided by the clock generator described in the previous section. this channel parameter is defined in the cpre field of the pwm_ cmrx register. this field is reset at 0. the waveform period . this channel parameter is defined in the cprd field of the pwm_cprdx register. - if the waveform is left aligned, then the output waveform period depends on the counter source clock and can be calculated: by using the master clock (mck) divided by an x given prescaler value (with x being 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, or 1024), the resulting period formula will be: by using a master clock divided by one of both diva or divb divider, the formula becomes, respectively: or if the waveform is center aligned then the output waveform period depends on the counter comparator pwmx output waveform internal counter clock selector inputs from clock generator inputs from apb bus channel x cprd () mck ------------------------------- crpd diva () mck ------------------------------------------ crpd divab () mck ----------------------------------------------
395 6042e?atarm?14-dec-06 at91sam7a3 preliminary source clock and can be calculated: by using the master clock (mck) divided by an x given prescaler value (with x being 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, or 1024). the resulting period formula will be: by using a master clock divided by one of both diva or divb divider, the formula becomes, respectively: or the waveform duty cycle . this channel parameter is defined in the cdty field of the pwm_cdtyx register. if the waveform is left aligned then: if the waveform is center aligned, then: the waveform polarity. at the beginning of the period, the signal can be at high or low level. this property is defined in the cpol field of the pwm_cmrx register. by default the signal starts by a low level. the waveform alignment . the output waveform can be left or center aligned. center aligned waveforms can be used to generate non overlapped waveforms. this property is defined in the calg field of the pwm_cmrx register. the default mode is left aligned. figure 32-4. non overlapped center aligned waveforms note: 1. see figure 32-5 on page 397 for a detailed description of center aligned waveforms. when center aligned, the internal channel counter increases up to cprd and.decreases down to 0. this ends the period. when left aligned, the internal channel counter increases up to cprd and is reset. this ends the period. thus, for the same cprd value, the period for a center aligned channel is twice the period for a left aligned channel. 2 x cprd () mck ---------------------------------------- - 2 cprd diva () mck --------------------------------------------------- - 2 cprd divb () mck --------------------------------------------------- - duty cycle period 1 fchannel_x_clock cdty ? ? () period ------------------------------------------------------------------------------------------------------- - = duty cycle period 2 ? () 1 fchannel_x_clock cdty ? ? ()) period 2 ? () ---------------------------------------------------------------------------------------------------------------------- - = pwm0 pwm1 period no overlap
396 6042e?atarm?14-dec-06 at91sam7a3 preliminary waveforms are fixed at 0 when: cdty = cprd and cpol = 0 cdty = 0 and cpol = 1 waveforms are fixed at 1 (once the channel is enabled) when: cdty = 0 and cpol = 0 cdty = cprd and cpol = 1 the waveform polarity must be set before enabling the channel. this immediately affects the channel output level. changes on channel polarity are not taken into account while the chan- nel is enabled.
397 6042e?atarm?14-dec-06 at91sam7a3 preliminary figure 32-5. waveform properties pwm_mckx chidx(pwm_sr) center aligned cprd(pwm_cprdx) cdty(pwm_cdtyx) pwm_ccntx output waveform pwmx cpol(pwm_cmrx) = 0 output waveform pwmx cpol(pwm_cmrx) = 1 chidx(pwm_isr) left aligned cprd(pwm_cprdx) cdty(pwm_cdtyx) pwm_ccntx output waveform pwmx cpol(pwm_cmrx) = 0 output waveform pwmx cpol(pwm_cmrx) = 1 chidx(pwm_isr) calg(pwm_cmrx) = 0 calg(pwm_cmrx) = 1 period period chidx(pwm_ena) chidx(pwm_dis)
398 6042e?atarm?14-dec-06 at91sam7a3 preliminary 32.5.3 pwm controller operations 32.5.3.1 initialization before enabling the output channel, this channel must have been configured by the software application: configuration of the clock generator if diva and divb are required selection of the clock for each channel (cpre field in the pwm_cmrx register) configuration of the waveform alignment for each channel (calg field in the pwm_cmrx register) configuration of the period for each channel (cprd in the pwm_cprdx register). writing in pwm_cprdx register is possible while the channel is disabled. after validation of the channel, the user must use pwm_cupdx register to update pwm_cprdx as explained below. configuration of the duty cycl e for each channel (cdty in the pwm_cdtyx register). writing in pwm_cdtyx register is possible wh ile the channel is disa bled. after validation of the channel, the user must use pwm_ cupdx register to update pwm_cdtyx as explained below. configuration of the output waveform polarity for each channel (cpol in the pwm_cmrx register) enable interrupts (writing chidx in the pwm_ier register) enable the pwm channel (writing chidx in the pwm_ena register) it is possible to synchronize different channels by enabling them at the same time by means of writing simultaneously several chidx bits in the pwm_ena register. in such a situation, all channels may have the same clock selector configuration and the same period specified. 32.5.3.2 source clock selection criteria the large number of source clocks can make se lection difficult. the relationship between the value in the period register (pwm_cprdx) and the duty cycle register (pwm_cdtyx) can help the user in choosing. the event number written in the period register gives the pwm accuracy. the duty cycle quantum cannot be lower than 1/pwm_cprdx value. the higher the value of pwm_cprdx, the greater the pwm accuracy. for example, if the user sets 15 (in decimal) in pwm_cprdx, the user is able to set a value between 1 up to 14 in pwm_cdtyx register. the resulting duty cycle quantum cannot be lower than 1/15 of the pwm period. 32.5.3.3 changing the duty cycle or the period it is possible to modulate the output waveform duty cycle or period. to prevent unexpected output waveform, the user must use the update register (pwm_cupdx) to change wavefo rm parameters while the chan nel is still enabled. the user can write a new period value or duty cycle value in the update register (pwm_cupdx). this register holds the new value until the end of the current cycle and updates the value for the next cycle. depending on the cpd field in t he pwm_cmrx register, pwm_cupdx either updates pwm_cprdx or pwm_cdtyx. note that even if the update register is used, the period must not be smaller than the duty cycle.
399 6042e?atarm?14-dec-06 at91sam7a3 preliminary figure 32-6. synchronized period or duty cycle update to prevent overwriting the pwm_cupdx by software, the user can use status events in order to synchronize his software. two methods are possible. in both, the user must enable the ded- icated interrupt in pwm_ie r at pwm controller level. the first method (polling method) consists of reading the re levant status bit in pwm_isr reg- ister according to the enabled channel(s). see figure 32-7 . the second method uses an interrupt service routine associated with the pwm channel. note: reading the pwm_isr register automatically clears chidx flags. figure 32-7. polling method note: polarity and alignment can be modified only when the channel is disabled. pwm_cupdx value pwm_cprdx pwm_cdtyx end of cycle pwm_cmrx. cpd user's writing 1 0 writing in pwm_cupdx the last write has been taken into account chidx = 1 writing in cpd field update of the period or duty cycle pwm_isr read acknowledgement and clear previous register state yes
400 6042e?atarm?14-dec-06 at91sam7a3 preliminary 32.5.3.4 interrupts depending on the interrupt mask in the pwm_imr register, an interrupt is generated at the end of the corresponding channel period. the interrupt remains active until a read operation in the pwm_isr register occurs. a channel interrupt is enabled by setting the corresponding bit in the pwm_ier register. a channel interrupt is disabled by setting th e corresponding bit in the pwm_idr register.
401 6042e?atarm?14-dec-06 at91sam7a3 preliminary 32.6 pulse width modulation (pwm ) controller user interface table 32-2. pwm controller registers offset register name access peripheral reset value 0x00 pwm mode register pwm_mr read/write 0 0x04 pwm enable register pwm_ena write-only - 0x08 pwm disable register pwm_dis write-only - 0x0c pwm status register pwm_sr read-only 0 0x10 pwm interrupt enable register pwm_ier write-only - 0x14 pwm interrupt disable register pwm_idr write-only - 0x18 pwm interrupt mask register pwm_imr read-only 0 0x1c pwm interrupt status register pwm_isr read-only 0 0x4c - 0xfc reserved ? ? ? 0x100 - 0x1fc reserved 0x200 channel 0 mode register pwm_cmr0 read/write 0x0 0x204 channel 0 duty cycle register pwm_cdty0 read/write 0x0 0x208 channel 0 period register pwm_cprd0 read/write 0x0 0x20c channel 0 counter register pwm_ccnt0 read-only 0x0 0x210 channel 0 update register pwm_cupd0 write-only - ... reserved 0x220 channel 1 mode register pwm_cmr1 read/write 0x0 0x224 channel 1 duty cycle register pwm_cdty1 read/write 0x0 0x228 channel 1 period register pwm_cprd1 read/write 0x0 0x22c channel 1 counter register pwm_ccnt1 read-only 0x0 0x230 channel 1 update register pwm_cupd1 write-only - ... ... ... ... ...
402 6042e?atarm?14-dec-06 at91sam7a3 preliminary 32.6.1 pwm mode register register name: pwm_mr access type: read/write diva, divb: clka, clkb divide factor prea, preb 31 30 29 28 27 26 25 24 ???? preb 23 22 21 20 19 18 17 16 divb 15 14 13 12 11 10 9 8 ???? prea 76543210 diva diva, divb clka, clkb 0 clka, clkb clock is turned off 1 clka, clkb clock is clock selected by prea, preb 2-255 clka, clkb clock is clock selected by prea, preb divided by diva, divb factor. prea, preb divider input clock 0000mck. 0001mck/2 0010mck/4 0011mck/8 0100mck/16 0101mck/32 0110mck/64 0111mck/128 1000mck/256 1001mck/512 1010mck/ 1024 other reserved
403 6042e?atarm?14-dec-06 at91sam7a3 preliminary 32.6.2 pwm enable register register name: pwm_ena access type: write-only chidx: channel id 0 = no effect. 1 = enable pwm output for channel x. 32.6.3 pwm disable register register name: pwm_dis access type: write-only chidx: channel id 0 = no effect. 1 = disable pwm output for channel x. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ???????? 76543210 chid7 chid6 chid5 chid4 chid3 chid2 chid1 chid0 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ???????? 76543210 chid7 chid6 chid5 chid4 chid3 chid2 chid1 chid0
404 6042e?atarm?14-dec-06 at91sam7a3 preliminary 32.6.4 pwm status register register name: pwm_sr access type: read-only chidx: channel id 0 = pwm output for channel x is disabled. 1 = pwm output for channel x is enabled. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ???????? 76543210 chid7 chid6 chid5 chid4 chid3 chid2 chid1 chid0
405 6042e?atarm?14-dec-06 at91sam7a3 preliminary 32.6.5 pwm interrupt enable register register name: pwm_ier access type: write-only chidx: channel id. 0 = no effect. 1 = enable interrupt for pwm channel x. 32.6.6 pwm interrupt disable register register name: pwm_idr access type: write-only chidx: channel id. 0 = no effect. 1 = disable interrupt for pwm channel x. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ???????? 76543210 chid7 chid6 chid5 chid4 chid3 chid2 chid1 chid0 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ???????? 76543210 chid7 chid6 chid5 chid4 chid3 chid2 chid1 chid0
406 6042e?atarm?14-dec-06 at91sam7a3 preliminary 32.6.7 pwm interrupt mask register register name: pwm_imr access type: read-only chidx: channel id. 0 = interrupt for pwm channel x is disabled. 1 = interrupt for pwm channel x is enabled. 32.6.8 pwm interrupt status register register name: pwm_isr access type: read-only chidx: channel id 0 = no new channel period has been achieved si nce the last read of the pwm_isr register. 1 = at least one new channel period has been achiev ed since the last read of the pwm_isr register. note: reading pwm_isr automa tically clears chidx flags. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ???????? 76543210 chid7 chid6 chid5 chid4 chid3 chid2 chid1 chid0 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ???????? 76543210 chid7 chid6 chid5 chid4 chid3 chid2 chid1 chid0
407 6042e?atarm?14-dec-06 at91sam7a3 preliminary 32.6.9 pwm channel mode register register name: pwm_cmrx access type: read/write cpre: channel pre-scaler calg: channel alignment 0 = the period is left aligned. 1 = the period is center aligned. cpol: channel polarity 0 = the output waveform starts at a low level. 1 = the output waveform starts at a high level. cpd: channel update period 0 = writing to the pwm_cupdx will modify the duty cycle at the next period start event. 1 = writing to the pwm_cupdx will modify th e period at the next period start event. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ?????cpdcpolcalg 76543210 ???? cpre cpre channel pre-scaler 0000mck 0001mck/2 0010mck/4 0011mck/8 0100mck/16 0101mck/32 0110mck/64 0111mck/128 1000mck/256 1001mck/512 1010mck/1024 1011clka 1100clkb other reserved
408 6042e?atarm?14-dec-06 at91sam7a3 preliminary 32.6.10 pwm channel duty cycle register register name: pwm_cdtyx access type: read/write only the first 20 bits (internal ch annel counter size) are significant. cdty: channel duty cycle defines the waveform duty cycle. this value must be defined between 0 and cprd (pwm_cprx). 31 30 29 28 27 26 25 24 cdty 23 22 21 20 19 18 17 16 cdty 15 14 13 12 11 10 9 8 cdty 76543210 cdty
409 6042e?atarm?14-dec-06 at91sam7a3 preliminary 32.6.11 pwm channel period register register name: pwm_cprdx access type: read/write only the first 20 bits (internal ch annel counter size) are significant. cprd: channel period if the waveform is left-aligned, then the output waveform period depends on the counter source clock and can be calculated: ? by using the master clock (mck) divided by an x given prescaler value (with x being 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, or 1024). the resu lting period formula will be: ? by using a master clock divided by one of both diva or divb divider, the formula becomes, respectively: or if the waveform is center-aligned, then the output waveform period depends on the counter source clock and can be calculated: ? by using the master clock (mck) divided by an x given prescaler value (with x being 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, or 1024) . the resulting pe riod formula will be: ? by using a master clock divided by one of both diva or divb divider, the formula becomes, respectively: or 31 30 29 28 27 26 25 24 cprd 23 22 21 20 19 18 17 16 cprd 15 14 13 12 11 10 9 8 cprd 76543210 cprd x cprd () mck ------------------------------- crpd diva () mck ------------------------------------------ crpd divab () mck ---------------------------------------------- 2 x cprd () mck ---------------------------------------- - 2 cprd diva () mck --------------------------------------------------- - 2 cprd divb () mck --------------------------------------------------- -
410 6042e?atarm?14-dec-06 at91sam7a3 preliminary 32.6.12 pwm channel counter register register name: pwm_ccntx access type: read-only cnt: channel counter register internal counter value. this register is reset when: the channel is enabled (writing chidx in the pwm_ena register). the counter reaches cprd value defined in the pwm_ cprdx register if the waveform is left aligned. 32.6.13 pwm channel update register register name: pwm_cupdx access type: write-only this register acts as a double buffer for the period or the duty cycle. this prevents an unexpected waveform when modify- ing the waveform period or duty-cycle. only the first 20 bits (internal ch annel counter size) are significant. 31 30 29 28 27 26 25 24 cnt 23 22 21 20 19 18 17 16 cnt 15 14 13 12 11 10 9 8 cnt 76543210 cnt 31 30 29 28 27 26 25 24 cupd 23 22 21 20 19 18 17 16 cupd 15 14 13 12 11 10 9 8 cupd 76543210 cupd cpd (pwm_cmrx register) 0 the duty-cycle (cdtc in the pwm_cdrx regist er) is updated with the cupd value at the beginning of the next period. 1 the period (cprd in the pwm_cprx register) is updated with the cupd value at the beginning of the next period.
411 6042e?atarm?14-dec-06 at91sam7a3 preliminary 33. usb device port (udp) 33.1 overview the usb device port (udp) is compliant with the universal serial bus (usb) v2.0 full-speed device specification. each endpoint can be configured in one of several usb transfer types. it can be associated with one or two banks of a dual-port ram used to store the current data payload. if two banks are used, one dpr bank is read or written by the proc essor, while the other is read or written by the usb device peripheral. this feature is mandator y for isochronous endpoints. thus the device maintains the maximum bandwidth (1m bytes/s) by working with endpoints with two banks of dpr. suspend and resume are automatically detected by the usb device, which notifies the proces- sor by raising an interrupt. depending on the product, an external signal can be used to send a wake up to the usb host controller. table 33-1. usb endpoint description endpoint number mnemonic dual-bank max. endpoint size endpoint type 0 ep0 no 8 control/bulk/interrupt 1 ep1 yes 64 bulk/iso/interrupt 2 ep2 yes 64 bulk/iso/interrupt 3 ep3 no 64 control/bulk/interrupt 4 ep4 yes 512 bulk/iso/interrupt 5 ep5 yes 512 bulk/iso/interrupt
412 6042e?atarm?14-dec-06 at91sam7a3 preliminary 33.2 block diagram figure 33-1. block diagram access to the udp is via the apb bus interface. read and write to the data fi fo are done by reading and writing 8-bit values to apb registers. the udp peripheral requires two clocks: one peripheral clock used by the mck domain and a 48 mhz clock used by the 12 mhz domain. a usb 2.0 full-speed pad is embedded and controlled by the serial interface engine (sie). the signal external_resume is optional. it allows the udp peripheral to wake up once in system mode. the host is then notified that the device asks for a resume. this optional feature must be also negotiated with the host during the enumeration. atmel bridge 12 mhz suspend/resume logic w r a p p e r w r a p p e r u s e r i n t e r f a c e serial interface engine sie mck master clock domain dual port ram fifo udpck recovered 12 mhz domain udp_int usb device embedded usb transceiver dp dm external_resume apb to mcu bus txoen eopn txd rxdm rxd rxdp
413 6042e?atarm?14-dec-06 at91sam7a3 preliminary 33.3 product dependencies for further details on the usb device hardware implementation, see the specific product prop- erties document. the usb physical transceiver is integrated into the product. the bidirectional differential signals dp and dm are available from the product boundary. two i/o lines may be used by the application: one to check that vbus is still available from the host. self-powered devices may use this entry to be notified that the host has been powered off. in this case, the board pullup on dp must be disabled in order to prevent feeding current to the host. one to control the board pullup on dp. thus, when the device is ready to communicate with the host, it activates its dp pullup through this control line. 33.3.1 i/o lines dp and dm are not controlled by any pio controllers. the embedded usb physical transceiver is controlled by the usb device peripheral. to reserve an i/o line to check vbus, the program mer must first program the pio controller to assign this i/o in input pio mode. to reserve an i/o line to control the board pullup, the programmer must first program the pio controller to assign this i/o in output pio mode. 33.3.2 power management the usb device peripheral requires a 48 mhz cl ock. this clock must be generated by a pll with an accuracy of 0.25%. thus, the usb device receives two clocks from the power management controller (pmc): the master clock, mck, used to drive the peripheral user interface, and the udpck, used to inter- face with the bus usb signals (recovered 12 mhz domain). warning: the udp peripheral clock in the power management controller (pmc) must be enabled before any read/write operations to the udp registers including the udp_txcv register. 33.3.3 interrupt the usb device interface has an interrupt line co nnected to the advanced interrupt controller (aic). handling the usb device interrupt requires programming the aic before configuring the udp.
414 6042e?atarm?14-dec-06 at91sam7a3 preliminary 33.4 typical connection figure 33-2. board schematic to interface usb device peripheral 33.4.1 usb device transceiver the usb device transceiver is embedded in the product. a few discrete components are required as follows: the application detects all device states as def ined in chapter 9 of the usb specification; ? pullup enable/disable ?vbus monitoring to reduce power consumption the host is disconnected for line termination. pullup enable/disable is done through a mosfet controlled by a pio. the pullup is enabled when the pio drives a 0. thus pio default state to 1 corresponds to a pullup disable. once the pullup is enabled, the host will force a device reset 100 ms later. bus powered devices must connect the pullup within 100 ms. 33.4.2 vbus monitoring vbus monitoring is required to detect host connection. vbus monitoring is done using a stan- dard pio with internal pullup disabled. when the host is switched off, it should be considered as a disconnect, the pullup must be disabled in order to prevent powering the host through the pull- up resistor. when the host is disconnected and the transceiver is enabled, then ddp and ddm are floating. this may lead to over consumption. a solution is to connect 330 k ? pulldowns on dp and dm. these pulldowns do not alter ddp and ddm signal integrity. 3v3 r ext ddm ddp pio pio 27 k 47 k 330 k type b connector 1 2 34 5v bus monitoring pullup control r ext 330 k 1.5k 0: enable 1: disable
415 6042e?atarm?14-dec-06 at91sam7a3 preliminary a termination serial resistor must be connected to dp and dm. the resistor value is defined in the electrical specification of the product (r ext ). 33.5 functional description 33.5.1 usb v2.0 full-speed introduction the usb v2.0 full-speed provides communication services between host and attached usb devices. each device is offered with a collection of communication flows (pipes) associated with each endpoint. software on the host communicates with a usb device through a set of commu- nication flows. figure 33-3. example of usb v2.0 full-speed communication control the control transfer endpoint ep0 is always used when a us b device is first configured (usb v. 2.0 specifications). 33.5.1.1 usb v2.0 full-speed transfer types a communication flow is carried over one of f our transfer types defined by the usb device. ep0 usb host v2.0 software client 1 software client 2 data flow: bulk out transfer data flow: bulk in transfer data flow: control transfer data flow: control transfer ep1 ep2 usb device 2.0 block 1 usb device 2.0 block 2 ep5 ep4 ep0 data flow: isochronous in transfer data flow: isochronous out transfer usb device endpoint configuration requires that in the first instance control transfer must be ep0. table 33-2. usb communication flow transfer direction bandwidth supported endpoint size error detection retrying control bidirectional not guaranteed 8, 16, 32, 64 yes automatic isochronous unidirectional guaranteed 512 yes no interrupt unidirectional not guaranteed 8, 16, 32, 64 yes yes bulk unidirectional not guaranteed 8, 16, 32, 64 yes yes
416 6042e?atarm?14-dec-06 at91sam7a3 preliminary 33.5.1.2 usb bus transactions each transfer results in one or more transactions over the usb bus. there are three kinds of transactions flowing acro ss the bus in packets: 1. setup transaction 2. data in transaction 3. data out transaction 33.5.1.3 usb transfer event definitions as indicated below, transfers are sequential events carried out on the usb bus. notes: 1. control transfer must use endpoints with no ping-pong attributes. 2. isochronous transfers must use endpoints with ping-pong attributes. 3. control transfers can be aborted using a stall handshake. a status transaction is a special type of host-to- device transaction used only in a control transfer. the control transfer must be performed using endpoints with no ping-pong attributes. according to the control sequence (read or write), the usb device sends or receives a status transaction. table 33-3. usb transfer events control transfers (1) (3) setup transaction > data in transactions > status out transaction setup transaction > data out transactions > status in transaction setup transaction > status in transaction interrupt in transfer (device toward host) data in transaction > data in transaction interrupt out transfer (host toward device) data out transaction > data out transaction isochronous in transfer (2) (device toward host) data in transaction > data in transaction isochronous out transfer (2) (host toward device) data out transaction > data out transaction bulk in transfer (device toward host) data in transaction > data in transaction bulk out transfer (host toward device) data out transaction > data out transaction
417 6042e?atarm?14-dec-06 at91sam7a3 preliminary figure 33-4. control read and write sequences notes: 1. during the status in stage, the host waits for a zero le ngth packet (data in transaction with no data) from the device using data1 pid. refer to chapter 8 of the universal serial bus specification, rev. 2.0, for more information on the protocol layer. 2. during the status out stage, the host emits a zero lengt h packet to the device (data out transaction with no data). 33.5.2 handling transactions with usb v2.0 device peripheral 33.5.2.1 setup transaction setup is a special type of host-to-device transaction used during control transfers. control trans- fers must be performed using endpoints with no ping-pong attributes. a setup transaction needs to be handled as soon as possible by the firmware. it is used to transmit requests from the host to the device. these requests are then handled by the usb device and may require more argu- ments. the arguments are sent to the device by a data out transaction which follows the setup transaction. these requests may also return data. the data is carried out to the host by the next data in transaction which follows the setup transaction. a status transaction ends the control transfer. when a setup transfer is received by the usb endpoint: the usb device automatically acknowledges the setup packet rxsetup is set in the udp_ csrx register an endpoint interrupt is generated while the rxsetup is not cleared. this interrupt is carried out to the microcontroller if interrupts are enabled for this endpoint. thus, firmware must detect th e rxsetup polling the udp_ csrx or catching an interrupt, read the setup packet in the fifo , then clear the rxsetup. rxsetup cannot be clear ed before the setup packet has been read in the fifo. otherwise, the usb device would accept the next data out transfer and overwrite the setup packet in the fifo. control read setup tx data out tx data out tx data stage control write setup stage setup stage setup tx setup tx no data control data in tx data in tx status stage status stage status in tx status out tx status in tx data stage setup stage status stage
418 6042e?atarm?14-dec-06 at91sam7a3 preliminary figure 33-5. setup transaction followed by a data out transaction 33.5.2.2 data in transaction data in transactions are used in control, is ochronous, bulk and interrupt transfers and conduct the transfer of data from the device to the host. data in transactions in isochronous transfer must be done using endpoints with ping-pong attributes. 33.5.2.3 using endpoints without ping-pong attributes to perform a data in transaction using a non ping-pong endpoint: 1. the application checks if it is possible to write in the fifo by polling txpktrdy in the endpoint?s udp_ csrx register (txpktrdy must be cleared). 2. the application writes the first packet of data to be sent in the endpoint?s fifo, writing zero or more byte values in the endpoint?s udp_ fdrx register, 3. the application notifies the usb peripheral it has finished by setting the txpktrdy in the endpoint?s udp_ csrx register. 4. the application is notified that the endpoint?s fifo has been released by the usb device when txcomp in the endpoint?s udp_ csrx register has been set. then an interrupt for the corresponding endpoint is pending while txcomp is set. 5. the microcontroller writes the second packet of data to be sent in the endpoint?s fifo, writing zero or more byte values in the endpoint?s udp_ fdrx register, 6. the microcontroller notifi es the usb peripheral it has finished by setting the txpk- trdy in the endpoint?s udp_ csrx register. 7. the application clears the txcomp in the endpoint?s udp_ csrx. after the last packet has been sent, the application must clear txcomp once this has been set. txcomp is set by the usb device when it has received an ack pid signal for the data in packet. an interrupt is pending while txcomp is set. warning: tx_comp must be cleared after tx_pktrdy has been set. note: refer to chapter 8 of the universal serial bus specification, rev 2.0, for more information on the data in protocol layer. rx_data_bko (udp_csrx) ack pid data out data out pid nak pid ack pid data setup setup pid usb bus packets rxsetup flag set by usb device cleared by firmware set by usb device peripheral fifo (dpr) content data setup data xx xx out interrupt pending setup received setup handled by firmware data out received data out data out pid
419 6042e?atarm?14-dec-06 at91sam7a3 preliminary figure 33-6. data in transfer for non ping-pong endpoint 33.5.2.4 using endpoints with ping-pong attribute the use of an endpoint with ping-pong attributes is necessary during isochronous transfer. this also allows handling the maximum bandwidth defined in the usb specification during bulk trans- fer. to be able to guarantee a constant or the maximum bandwidth, the microcontroller must prepare the next data payload to be sent while the current one is being sent by the usb device. thus two banks of memory are used. while one is available for the microcontroller, the other one is locked by the usb device. figure 33-7. bank swapping data in transfer for ping-pong endpoints usb bus packets data in 2 data in nak ack data in 1 fifo (dpr) content data in 2 load in progress data in 1 cleared by firmware dpr access by the firmware payload in fifo txcomp flag (udp_csrx) txpktrdy flag (udp_csrx) pid data in data in pid pid pid pid ack pid prevous data in tx microcontroller load data in fifo data is sent on usb bus interrupt pending interrupt pending set by the firmware set by the firmware cleared by firmware cleared by hw cleared by hw dpr access by the hardware usb device usb bus read write read and write at the same time 1 st data payload 2 nd data payload 3 rd data payload 3 rd data payload 2 nd data payload 1 st data payload data in packet data in packet data in packet microcontroller endpoint 1 bank 0 endpoint 1 bank 1 endpoint 1 bank 0 endpoint 1 bank 0 endpoint 1 bank 0 endpoint 1 bank 1
420 6042e?atarm?14-dec-06 at91sam7a3 preliminary when using a ping-pong endpoint, the following procedures are required to perform data in transactions: 1. the microcontroller checks if it is possible to write in the fifo by polling txpktrdy to be cleared in the endpoint?s udp_ csrx register. 2. the microcontroller writes the first data payload to be sent in the fifo (bank 0), writing zero or more byte values in the endpoint?s udp_ fdrx register. 3. the microcontroller notifies the usb peripheral it has finished writing in bank 0 of the fifo by setting the txpktrdy in the endpoint?s udp_ csrx register. 4. without waiting for txpktrdy to be cleare d, the microcontrolle r writes the second data payload to be sent in the fifo (bank 1), writing zero or more byte values in the endpoint?s udp_ fdrx register. 5. the microcontroller is notified that the first bank has been released by the usb device when txcomp in the endpoint?s udp_ csrx re gister is set. an interrupt is pending while txcomp is being set. 6. once the microcontroller has received txco mp for the first bank, it notifies the usb device that it has prepared the second bank to be sent rising txpktrdy in the end- point?s udp_ csrx register. 7. at this step, bank 0 is available and the microcontroller can prepare a third data pay- load to be sent . figure 33-8. data in transfer for ping-pong endpoint warning: there is software critical path due to the fact that once the second bank is filled, the driver has to wait for tx_comp to set tx_pktrdy. if the delay between receiving tx_comp is set and tx_pktrdy is set is too long, some data in packets may be nacked, reducing the bandwidth. warning: tx_comp must be cleared after tx_pktrdy has been set. data in data in read by usb device read by usb device bank 1 bank 0 fifo (dpr) txcomp flag (udp_csrx) interrupt cleared by firmware set by usb device txpktrdy flag (udp_mcsrx) ack pid data in pid ack pid set by firmware, data payload written in fifo bank 1 cleared by usb device, data payload fully transmitted data in pid usb bus packets set by usb device set by firmware, data payload written in fifo bank 0 written by fifo (dpr) microcontroller written by microcontroller written by microcontroller microcontroller load data in bank 0 microcontroller load data in bank 1 usb device send bank 0 microcontroller load data in bank 0 usb device send bank 1 interrupt pending
421 6042e?atarm?14-dec-06 at91sam7a3 preliminary 33.5.2.5 data out transaction data out transactions are used in control, isochronous, bulk and interru pt transfers and con- duct the transfer of data from the host to the device. data out transactions in isochronous transfers must be done using endpoints with ping-pong attributes. 33.5.2.6 data out transaction without ping-pong attributes to perform a data out transaction, using a non ping-pong endpoint: 1. the host generates a data out packet. 2. this packet is received by the usb device endpoint. while the fifo associated to this endpoint is being used by the microcontroller, a nak pid is returned to the host. once the fifo is available, data are written to the fifo by the usb device and an ack is automatically carried out to the host. 3. the microcontroller is notifie d that the usb device has re ceived a data payload polling rx_data_bk0 in the endpoint?s udp_ csrx register. an interrupt is pending for this endpoint while rx_data_bk0 is set. 4. the number of bytes available in the fi fo is made available by reading rxbytecnt in the endpoint?s udp_ csrx register. 5. the microcontroller carries out data received from the endpoint?s memory to its mem- ory. data received is available by reading the endpoint?s udp_ fdrx register. 6. the microcontroller notifies the usb device that it has finished the transfer by clearing rx_data_bk0 in the endpoint?s udp_ csrx register. 7. a new data out packet can be accepted by the usb device. figure 33-9. data out transfer for non ping-pong endpoints an interrupt is pending while the flag rx_dat a_bk0 is set. memory transfer between the usb device, the fifo and microcontroller memory can not be done after rx_data_bk0 has been cleared. otherwise, the usb device would acce pt the next data out transfer and overwrite the current data out packet in the fifo. ack pid data out nak pid pid pid pid pid data out2 ack data out data out 1 usb bus packets rx_data_bk0 set by usb device cleared by firmware, data payload written in fifo fifo (dpr) content written by usb device microcontroller read data out 1 data out 1 data out 2 host resends the next data payload microcontroller transfers data host sends data payload data out2 data out2 host sends the next data payload written by usb device (udp_csrx) interrupt pending
422 6042e?atarm?14-dec-06 at91sam7a3 preliminary 33.5.2.7 using endpoints with ping-pong attributes during isochronous transfer, using an endpoint wit h ping-pong attributes is obligatory. to be able to guarantee a constant bandwidth, the micr ocontroller must read the previous data pay- load sent by the host, while the current data payload is received by the usb device. thus two banks of memory are used. while one is available for the microcontroller, the other one is locked by the usb device. figure 33-10. bank swapping in data out transfers for ping-pong endpoints when using a ping-pong endpoint, the following procedures are required to perform data out transactions: 1. the host generates a data out packet. 2. this packet is received by the usb device endpoint. it is written in the endpoint?s fifo bank 0. 3. the usb device sends an ack pid packet to the host. the host can immediately send a second data out packet. it is accepted by the device and copied to fifo bank 1. 4. the microcontroller is notifi ed that the usb device has re ceived a data payload, polling rx_data_bk0 in the endpoint?s udp_ csrx register. an interrupt is pending for this endpoint while rx_data_bk0 is set. 5. the number of bytes available in the fi fo is made available by reading rxbytecnt in the endpoint?s udp_ csrx register. 6. the microcontroller transfers out data received from the endpoint?s memory to the microcontroller?s memory. data received is made available by reading the endpoint?s udp_ fdrx register. 7. the microcontroller notifies the usb peripheral device that it has finished the transfer by clearing rx_data_bk0 in the endpoint?s udp_ csrx register. 8. a third data out packet can be accepted by the usb peripheral device and copied in the fifo bank 0. 9. if a second data out packet has been received, the microcontroller is notified by the flag rx_data_bk1 set in the endpoint?s udp_ csrx register. an interrupt is pending for this endpoint while rx_data_bk1 is set. usb device usb bus read write write and read at the same time 1 st data payload 2 nd data payload 3 rd data payload 3 rd data payload 2 nd data payload 1 st data payload data in packet data in packet data in packet microcontroller endpoint 1 bank 0 endpoint 1 bank 1 endpoint 1 bank 0 endpoint 1 bank 0 endpoint 1 bank 0 endpoint 1 bank 1
423 6042e?atarm?14-dec-06 at91sam7a3 preliminary 10. the microcontroller transfers out data received from the endpoint?s memory to the microcontroller?s memory. data received is available by reading the endpoint?s udp_ fdrx register. 11. the microcontroller notifies the usb device it has finished the transfer by clearing rx_data_bk1 in the endpoint?s udp_ csrx register. 12. a fourth data out packet can be accepted by the usb device and copied in the fifo bank 0. figure 33-11. data out transfer for ping-pong endpoint note: an interrupt is pending while the rx_data_bk0 or rx_data_bk1 flag is set. warning : when rx_data_bk0 and rx_data_bk1 are both set, there is no way to determine which one to clear first. thus the software must keep an internal counter to be sure to clear alter- natively rx_data_bk0 then rx_data_bk1. this situation may occur when the software application is busy elsewhere and the two banks are filled by the usb host. once the application comes back to the usb driver, the two flags are set. 33.5.2.8 stall handshake a stall handshake can be used in one of two distinct occasions. (for more information on the stall handshake, refer to chapter 8 of the universal serial bus specification, rev 2.0. ) a functional stall is used when the halt feature associated with the endpoint is set. (refer to chapter 9 of the universal serial bus sp ecification, rev 2.0, for more information on the halt feature.) to abort the current request, a protocol stall is used, but uniquely with control transfer. the following procedure generates a stall packet: a p data out pid ack data out 3 data out data out 2 data out data out 1 pid data out 3 data out 1 data out1 data out 2 data out 2 pid pid pid ack cleared by firmware usb bus packets rx_data_bk0 flag rx_data_bk1 flag set by usb device, data payload written in fifo endpoint bank 1 fifo (dpr) bank 0 bank 1 write by usb device write in progress read by microcontroller read by microcontroller set by usb device, data payload written in fifo endpoint bank 0 host sends first data payload microcontroller reads data 1 in bank 0, host sends second data payload microcontroller reads data2 in bank 1, host sends third data payload cleared by firmware write by usb device fifo (dpr) (udp_csrx) (udp_csrx) interrupt pending interrupt pending
424 6042e?atarm?14-dec-06 at91sam7a3 preliminary 1. the microcontroller sets the forcestall flag in the udp_ csrx endpoint?s register. 2. the host receives the stall packet. 3. the microcontroller is notif ied that the device has sent the stall by polling the stallsent to be set. an endpoint interrup t is pending while stallsent is set. the microcontroller must clear stallsent to clear the interrupt. when a setup transaction is received after a stall handshake, stallsent must be cleared in order to prevent interrupts due to stallsent being set. figure 33-12. stall handshake (data in transfer) figure 33-13. stall handshake (data out transfer) data in stall pid pid usb bus packets cleared by firmware set by firmware forcestall stallsent set by usb device cleared by firmware interrupt pending data out pid stall pid data out usb bus packets cleared by firmware set by firmware forcestall stallsent set by usb device interrupt pending
425 6042e?atarm?14-dec-06 at91sam7a3 preliminary 33.5.3 controlling device states a usb device has several possible states. refer to chapter 9 of the universal serial bus speci- fication, rev 2.0 . figure 33-14. usb device state diagram movement from one state to another depends on the usb bus state or on standard requests sent through control transactions via the default endpoint (endpoint 0). after a period of bus inactivity, the us b device enters suspend mode. accepting sus- pend/resume requests from the usb host is mandatory. constraints in suspend mode are very strict for bus-powered applications; devices may not consume more than 500 a on the usb bus. while in suspend mode, the host may wake up a de vice by sending a resume signal (bus activ- ity) or a usb device may send a wake up request to the host, e.g., waking up a pc by moving a usb mouse. the wake up feature is not mandatory for all devices and must be negotiated with the host. attached suspended suspended suspended suspended hub reset or deconfigured hub configured bus inactive bus activity bus inactive bus activity bus inactive bus activity bus inactive bus activity reset reset address assigned device deconfigured device configured powered default address configured power interruption
426 6042e?atarm?14-dec-06 at91sam7a3 preliminary 33.5.3.1 not powered state self powered devices can detect 5v vbus using a pio as described in the typical connection section. when the device is not connected to a host, device power consumption can be reduced by disabling mck for the udp, disabling udp ck and disabling the transceiver. ddp and ddm lines are pulled down by 330 k ? resistors. 33.5.3.2 entering attached state when no device is connected, the usb dp and dm signals are tied to gnd by 15 k ? pull-down resistors integrated in the hub downstream ports. when a device is attached to a hub down- stream port, the device connects a 1.5 k ? pull-up resistor on dp. the usb bus line goes into idle state, dp is pulled up by the device 1.5 k ? resistor to 3.3v and dm is pulled down by the 15 k ? resistor of the host. after pullup connection, the device enters the powered state. in this state, the udpck and mck must be enabled in the power management controller. the transceiver can remain disabled. 33.5.3.3 from powered state to default state after its connection to a usb host, the usb device waits for an end-of-bus reset. the unmaskable flag endbusres is set in the register udp_isr and an interrupt is triggered. once the endbusres interrupt has been triggered, the device enters default state. in this state, the udp software must: enable the default endpoint, setting the epeds flag in the udp_csr[0] register and, optionally, enabling the interrupt for endpoint 0 by writing 1 to the udp_ier register. the enumeration then begins by a control transfer. configure the interrupt mask register which has been reset by the usb reset detection enable the transceiver clearing the txvdis flag in the udp_txvc register. in this state udpck and mck must be enabled. warning : each time an endbusres interrupt is triggered, the interrupt mask register and udp_csr registers have been reset. 33.5.3.4 from default state to address state after a set address standard device request, the usb host peripheral enters the address state. warning : before the device enters in address state, it must achieve the status in transaction of the control transfer, i.e., the udp device sets its new address once the txcomp flag in the udp_csr[0] register has been received and cleared. to move to address state, the driver software sets the fadden flag in the udp_glb_stat register, sets its new address, and sets the fen bit in the udp_faddr register. 33.5.3.5 from address state to configured state once a valid set configuration standard request has been received and acknowledged, the device enables endpoints corresponding to the current configuration. this is done by setting the epeds and eptype fields in the udp_csrx regist ers and, optionally, en abling corr esponding interrupts in the udp_ier register.
427 6042e?atarm?14-dec-06 at91sam7a3 preliminary 33.5.3.6 entering in suspend state when a suspend (no bus activity on the usb bus) is detected, the rxsusp signal in the udp_isr register is set. this triggers an interrupt if the co rresponding bit is set in the udp_imr register.this flag is cleared by writing to the ud p_icr register. then the device enters suspend mode. in this state bus powered devices must drain less than 500ua from the 5v vbus. as an exam- ple, the microcontroller switches to slow clock, disables the pl l and main oscilla tor, and goes into idle mode. it may also switch off other devices on the board. the usb device peripheral clocks can be s witched off. resume event is asynchronously detected. mck and udpck can be switched off in the power management controller and the usb transceiver can be disabled by setting the txvdis field in the udp_txvc register. warning : read, write operations to the udp registers are allowed only if mck is enabled for the udp peripheral. switching off mck for the udp peripheral must be one of the last operations after writing to the udp_txvc and acknowledging the rxsusp. 33.5.3.7 receiving a host resume in suspend mode, a resume event on the usb bus line is detected asynchronously, transceiver and clocks are disabled (however the pullup shall not be removed). once the resume is detected on the bus, the wakeup signal in the udp_isr is set. it may gen- erate an interrupt if the corresponding bit in the udp_imr register is set. this interrupt may be used to wake up the core, enable pll a nd main oscillators and configure clocks. warning : read, write operations to the udp registers are allowed only if mck is enabled for the udp peripheral. mck for the udp must be enabled before clea ring the wakeup bit in the udp_icr register and clearing txvdis in the udp_txvc register. 33.5.3.8 sending a device remote wakeup in suspend state it is possible to wake up the host sending an external resume. the device must wait at least 5 ms after being entered in suspend before sending an external resume. the device has 10 ms from the moment it starts to drain current and it forces a k state to resume the host. the device must force a k state from 1 to 15 ms to resume the host to force a k state to the bus (dm at 3.3v and dp tied to gnd), it is possible to use a transistor to connect a pullup on dm. the k state is obt ained by disabling the pullup on dp and enabling the pullup on dm. this should be under the control of the application.
428 6042e?atarm?14-dec-06 at91sam7a3 preliminary figure 33-15. board schematic to drive a k state 3v3 pio 1.5 k 0: force wake up (k state) 1: normal mode dm
429 6042e?atarm?14-dec-06 at91sam7a3 preliminary 33.6 usb device port (udp) user interface warning: the udp peripheral clock in the power management controller (pmc) must be enabled before any read/write operations to the udp registers including the udp_txcv register. notes: 1. the addresses of the udp_ csrx registers ar e calculated as: 0x030 + 4(endpoint number - 1). 2. the addresses of the udp_ fdrx registers are calculated as: 0x050 + 4(endpoint number - 1). 3. see warning above the ?udp memory map? on this page. table 33-4. udp memory map offset register name access reset state 0x000 frame number register udp_ frm_num read 0x0000_0000 0x004 global state register udp_ glb_stat read/write 0x0000_0000 0x008 function address register udp_ faddr read/write 0x0000_0100 0x00c reserved ? ? ? 0x010 interrupt enable register udp_ ier write 0x014 interrupt disable register udp_ idr write 0x018 interrupt mask register udp_ imr read 0x0000_1200 0x01c interrupt status register udp_ isr read 0x0000_xx00 0x020 interrupt clear register udp_ icr write 0x024 reserved ? ? ? 0x028 reset endpoint register udp_ rst_ep read/write 0x02c reserved ? ? ? 0x030 endpoint 0 control and status register udp_csr0 read/write 0x0000_0000 . . . . . . see note: (1) endpoint 5 control and status register udp_csr5 read/write 0x0000_0000 0x050 endpoint 0 fifo data register udp_ fdr0 read/write 0x0000_0000 . . . . . . see note: (2) endpoint 5 fifo data register udp_ fdr5 read/write 0x0000_0000 0x070 reserved ? ? ? 0x074 transceiver control register udp_ txvc (3) read/write 0x0000_0000 0x078 - 0xfc reserved ? ? ?
430 6042e?atarm?14-dec-06 at91sam7a3 preliminary 33.6.1 udp frame number register register name: udp_ frm_num access type: read-only frm_num[10:0]: frame number as defined in the packet field formats this 11-bit value is incremented by the host on a per fr ame basis. this value is updated at each start of frame. value updated at the sof_eop (start of frame end of packet). frm_err: frame error this bit is set at sof_eop when the sof packet is received containing an error. this bit is reset upon receipt of sof_pid. frm_ok: frame ok this bit is set at sof_eop when the sof packet is received without any error. this bit is reset upon receipt of sof_pid (packet identification). in the interrupt status register, the sof interrupt is updated upon receiving sof_pid. this bit is set without waiting for eop. note: in the 8-bit register interfac e, frm_ok is bit 4 of frm_num_h and frm_err is bit 3 of frm_num_l. 31 30 29 28 27 26 25 24 --- --- --- --- --- --- --- --- 23 22 21 20 19 18 17 16 ??????frm_okfrm_err 15 14 13 12 11 10 9 8 ????? frm_num 76543210 frm_num
431 6042e?atarm?14-dec-06 at91sam7a3 preliminary 33.6.2 udp global state register register name: udp_ glb_stat access type: read/write this register is used to get and set the device state as specified in chapter 9 of the usb serial bus specification, rev.2.0 . fadden: function address enable read: 0 = device is not in address state. 1 = device is in address state. write: 0 = no effect, only a reset can bring back a device to the default state. 1 = sets device in address state. this occurs after a succe ssful set address request. beforehand, the udp_ faddr regis- ter must have been initialized with set address parameters. set address must complete the status stage before setting fadden. refer to chapter 9 of the universal serial bus specification, rev. 2.0 for more details. confg: configured read: 0 = device is not in configured state. 1 = device is in configured state. write: 0 = sets device in a non configured state 1 = sets device in configured state. the device is set in configured state when it is in address st ate and receives a successful set configuration request. refer to chapter 9 of the universal serial bus specification, rev. 2.0 for more details. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ?????? ?? 76543210 ??????confgfadden
432 6042e?atarm?14-dec-06 at91sam7a3 preliminary 33.6.3 udp function address register register name: udp_ faddr access type: read/write fadd[6:0]: function address value the function address value must be programmed by firmware once the device receives a set address request from the host, and has achieved the status stage of the no-data control sequence. refer to the universal serial bus specification, rev. 2.0 for more information. after power up or reset, the function address value is set to 0. fen: function enable read: 0 = function endpoint disabled. 1 = function endpoint enabled. write: 0 = disables function endpoint. 1 = default value. the function enable bit (fen) allows the microcontroller to enable or disable the function endpoints. the microcontroller sets this bit after receipt of a reset from the host. once this bit is set, the usb device is able to accept and transfer data packets from and to the host. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ?????? ?fen 76543210 ?fadd
433 6042e?atarm?14-dec-06 at91sam7a3 preliminary 33.6.4 udp interrupt enable register register name: udp_ ier access type: write-only ep0int: enable endpoint 0 interrupt ep1int: enable endpoint 1 interrupt ep2int: enable endpoint 2interrupt ep3int: enable endpoint 3 interrupt ep4int: enable endpoint 4 interrupt ep5int: enable endpoint 5 interrupt 0 = no effect. 1 = enables corresponding endpoint interrupt. rxsusp: enable udp suspend interrupt 0 = no effect. 1 = enables udp suspend interrupt. rxrsm: enable udp resume interrupt 0 = no effect. 1 = enables udp resume interrupt. sofint: enable start of frame interrupt 0 = no effect. 1 = enables start of frame interrupt. wakeup: enable udp bus wakeup interrupt 0 = no effect. 1 = enables usb bus interrupt. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ? ? wakeup ? sofint ? rxrsm rxsusp 76543210 ep5int ep4int ep3int ep2int ep1int ep0int
434 6042e?atarm?14-dec-06 at91sam7a3 preliminary 33.6.5 udp interrupt disable register register name: udp_ idr access type: write-only ep0int: disable endpoint 0 interrupt ep1int: disable endpoint 1 interrupt ep2int: disable endpoint 2 interrupt ep3int: disable endpoint 3 interrupt ep4int: disable endpoint 4 interrupt ep5int: disable endpoint 5 interrupt 0 = no effect. 1 = disables corresponding endpoint interrupt. rxsusp: disable udp suspend interrupt 0 = no effect. 1 = disables udp suspend interrupt. rxrsm: disable udp resume interrupt 0 = no effect. 1 = disables udp resume interrupt. sofint: disable start of frame interrupt 0 = no effect. 1 = disables start of frame interrupt wakeup: disable usb bus interrupt 0 = no effect. 1 = disables usb bus wakeup interrupt. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ? ? wakeup ? sofint ? rxrsm rxsusp 76543210 ep5int ep4int ep3int ep2int ep1int ep0int
435 6042e?atarm?14-dec-06 at91sam7a3 preliminary 33.6.6 udp interrupt mask register register name: udp_ imr access type: read-only note: 1. bit 12 of udp_imr cannot be masked and is always read at 1. ep0int: mask endpoint 0 interrupt ep1int: mask endpoint 1 interrupt ep2int: mask endpoint 2 interrupt ep3int: mask endpoint 3 interrupt ep4int: mask endpoint 4 interrupt ep5int: mask endpoint 5 interrupt 0 = corresponding endpoint interrupt is disabled. 1 = corresponding endpoint interrupt is enabled. rxsusp: mask udp suspend interrupt 0 = udp suspend interrupt is disabled. 1 = udp suspend interrupt is enabled. rxrsm: mask udp resume interrupt. 0 = udp resume interrupt is disabled. 1 = udp resume interrupt is enabled. sofint: mask start of frame interrupt 0 = start of frame interrupt is disabled. 1 = start of frame interrupt is enabled. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 (1) 11 10 9 8 ? ? wakeup ? sofint ? rxrsm rxsusp 76543210 ep5int ep4int ep3int ep2int ep1int ep0int
436 6042e?atarm?14-dec-06 at91sam7a3 preliminary wakeup: usb bus wakeup interrupt 0 = usb bus wakeup interrupt is disabled. 1 = usb bus wakeup interrupt is enabled. note: when the usb block is in suspend mode, the application may po wer down the usb logic. in this case, any usb host resume request that is made must be taken into account and, thus, the reset value of th e rxrsm bit of the register udp_ imr is enabled.
437 6042e?atarm?14-dec-06 at91sam7a3 preliminary 33.6.7 udp interrupt status register register name: udp_ isr access type: read-only ep0int: endpoint 0 interrupt status ep1int: endpoint 1 interrupt status ep2int: endpoint 2 interrupt status ep3int: endpoint 3 interrupt status ep4int: endpoint 4 interrupt status ep5int: endpoint 5 interrupt status 0 = no endpoint0 interrupt pending. 1 = endpoint0 interrupt has been raised. several signals can generate this interrupt. the reason can be found by reading udp_ csr0: rxsetup set to 1 rx_data_bk0 set to 1 rx_data_bk1 set to 1 txcomp set to 1 stallsent set to 1 ep0int is a sticky bit. interrupt remains valid until ep0int is cleared by writing in the corresponding udp_ csr0 bit. rxsusp: udp suspend interrupt status 0 = no udp suspend interrupt pending. 1 = udp suspend interrupt has been raised. the usb device sets this bit when it detects no ac tivity for 3ms. the usb device enters suspend mode. rxrsm: udp resume interrupt status 0 = no udp resume interrupt pending. 1 =udp resume interrupt has been raised. the usb device sets this bit when a udp resume signal is detected at its port. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ? ? wakeup endbusres sofint ? rxrsm rxsusp 76543210 ep5int ep4int ep3int ep2int ep1int ep0int
438 6042e?atarm?14-dec-06 at91sam7a3 preliminary after reset, the state of this bit is undefined, the application must clear this bit by setting the rxrsm flag in the udp_ icr register. sofint: start of frame interrupt status 0 = no start of frame interrupt pending. 1 = start of frame interrupt has been raised. this interrupt is raised each time a sof token has been detected. it can be used as a synchronization signal by using isochronous endpoints. endbusres: end of bus reset interrupt status 0 = no end of bus reset interrupt pending. 1 = end of bus reset interrupt has been raised. this interrupt is raised at the end of a udp reset sequence. the usb device must prepare to receive requests on the end- point 0. the host starts the enumeration, then performs the configuration. wakeup: udp resume interrupt status 0 = no wakeup interrupt pending. 1 = a wakeup interrupt (usb host sent a resume or reset) occurred since the last clear. after reset the state of this bit is undefined, the applic ation must clear this bit by sett ing the wakeup flag in the udp_ icr register.
439 6042e?atarm?14-dec-06 at91sam7a3 preliminary 33.6.8 udp interrupt clear register register name: udp_ icr access type: write-only rxsusp: clear udp suspend interrupt 0 = no effect. 1 = clears udp suspend interrupt. rxrsm: clear udp resume interrupt 0 = no effect. 1 = clears udp resume interrupt. sofint: clear start of frame interrupt 0 = no effect. 1 = clears start of frame interrupt. endbusres: clear end of bus reset interrupt 0 = no effect. 1 = clears end of bus reset interrupt. wakeup: clear wakeup interrupt 0 = no effect. 1 = clears wakeup interrupt. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ? ? wakeup endbusres sofint ? rxrsm rxsusp 76543210 ????????
440 6042e?atarm?14-dec-06 at91sam7a3 preliminary 33.6.9 udp reset en dpoint register register name: udp_ rst_ep access type: read/write ep0: reset endpoint 0 ep1: reset endpoint 1 ep2: reset endpoint 2 ep3: reset endpoint 3 ep4: reset endpoint 4 ep5: reset endpoint 5 this flag is used to reset the fifo associated with the endpoint and the bit rxbytecount in the register udp_csrx.it also resets the data toggle to data0. it is useful after removing a halt cond ition on a bulk endpoint. refer to chapter 5.8.5 in the usb serial bus specification, rev.2.0 . warning: this flag must be cleared at the end of the reset. it does not clear udp_ csrx flags. 0 = no reset. 1 = forces the corresponding end point fif0 pointers to 0, ther efore rxbytecnt field is read at 0 in udp_ csrx register. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ?????? ?? 76543210 ep5 ep4 ep3 ep2 ep1 ep0
441 6042e?atarm?14-dec-06 at91sam7a3 preliminary 33.6.10 udp endpoint control and status register register name: udp_ csrx [x = 0..5] access type: read/write warning : due to synchronization between mck and udpck, the soft ware application must wait for the end of the write operation before executing an other write by pollin g the bits which must be set/cleared. //! clear flags of udp udp_csr register and waits for synchronization #define udp_ep_clr_flag(pinterface, endpoint, flags) { \ while (pinterface->udp_csr[endpoint] & (flags)) \ pinterface->udp_csr[endpoint] &= ~(flags); \ } //! set flags of udp udp_csr register and waits for synchronization #define udp_ep_set_flag(pinterface, endpoint, flags) { \ while ( (pinterface->udp_csr[endpoint] & (flags)) != (flags) ) \ pinterface->udp_csr[endpoint] |= (flags); \ } txcomp: generates an in packet with data previously written in the dpr this flag generates an interr upt while it is set to one. write (cleared by the firmware): 0 = clear the flag, clear the interrupt. 1 = no effect. read (set by the usb peripheral): 0 = data in transaction has not been acknowledged by the host. 1 = data in transaction is achieved, acknowledged by the host. after having issued a data in transaction setting txpktrdy, the device firmware waits for txcomp to be sure that the host has acknowledged the transaction. rx_data_bk0: receive data bank 0 this flag generates an interr upt while it is set to one. write (cleared by the firmware): 0 = notify usb peripheral device that data have been read in the fifo's bank 0. 31 30 29 28 27 26 25 24 ????? r xbytecnt 23 22 21 20 19 18 17 16 rxbytecnt 15 14 13 12 11 10 9 8 epeds ? ? ? dtgle eptype 76543210 dir rx_data_ bk1 force stall txpktrdy stallsent isoerror rxsetup rx_data_ bk0 txcomp
442 6042e?atarm?14-dec-06 at91sam7a3 preliminary 1 = no effect. read (set by the usb peripheral): 0 = no data packet has been received in the fifo's bank 0. 1 = a data packet has been received, it has been stored in the fifo's bank 0. when the device firmware has polled this bit or has been interr upted by this signal, it must transfer data from the fifo to the microcontroller memory. the nu mber of bytes received is ava ilable in rxbytcent field. ba nk 0 fifo values are read through the udp_ fdrx register. once a transfer is done, the device firmware must release bank 0 to the usb peripheral device by clearing rx_data_bk0. rxsetup: received setup this flag generates an interr upt while it is set to one. read: 0 = no setup packet available. 1 = a setup data packet has been sent by the host and is available in the fifo. write: 0 = device firmware notifies the usb peripheral device that it has read the setup data in the fifo. 1 = no effect. this flag is used to notify the usb device firmware that a valid setup data packet has been sent by the host and success- fully received by the usb device. the usb device firmware ma y transfer setup data from the fifo by reading the udp_ fdrx register to the mi crocontroller memory. once a tr ansfer has been done, rxsetup mu st be cleared by the device firmware. ensuing data out transaction is not accepted while rxsetup is set. stallsent: stall sent (control, bulk interrupt endpoints) / isoerror (isochronous endpoints) this flag generates an interr upt while it is set to one. stallsent: this ends a stall handshake. read: 0 = the host has not acknowledged a stall. 1 = host has acknowledged the stall. write: 0 = resets the stallsent flag, clears the interrupt. 1 = no effect. this is mandatory for the device firmware to clear this flag. otherwise the interrupt remains. refer to chapters 8.4.5 and 9.4.5 of the universal serial bus s pecification, rev. 2.0 for more information on the stall handshake. isoerror: a crc error has been detected in an isochronous transfer. read: 0 = no error in the prev ious isochronous transfer. 1 = crc error has been detected, data available in the fifo are corrupted. write:
443 6042e?atarm?14-dec-06 at91sam7a3 preliminary 0 = resets the isoerror flag, clears the interrupt. 1 = no effect. txpktrdy: transmit packet ready this flag is cleared by the usb device. this flag is set by the usb device firmware. read: 0 = can be set to one to send the fifo data. 1 = the data is waiting to be sent upon reception of token in. write: 0 = no effect. 1 = a new data payload is has been written in the fifo by the firmware and is ready to be sent. this flag is used to generate a data in transaction (device to host). device firmware checks that it can write a data payload in the fifo, checking that txpktrdy is clear ed. transfer to the fifo is done by writing in the udp_ fdrx register. once the data payload has been transferred to the fifo, the firmwar e notifies the usb device setting txpktrdy to one. usb bus transactions can start. txcomp is set once the data payload has been received by the host. forcestall: force stall (used by control, bulk and isochronous endpoints) read: 0 = normal state. 1 = stall state. write: 0 = return to normal state. 1 = send stall to the host. refer to chapters 8.4.5 and 9.4.5 of the universal serial bus s pecification, rev. 2.0 for more information on the stall handshake. control endpoints: during the data stage and status stage, this bit indicates that the microcontroller cannot complete the request. bulk and interrupt endpoints: this bit notifies the host that the endpoint is halted. the host acknowledges the stall, device fi rmware is notified by the stallsent flag. rx_data_bk1: receive data bank 1 (only used by endpoints with ping-pong attributes) this flag generates an interr upt while it is set to one. write (cleared by the firmware): 0 = notifies usb device that data have been read in the fifo?s bank 1. 1 = no effect. read (set by the usb peripheral): 0 = no data packet has been received in the fifo's bank 1. 1 = a data packet has been received, it has been stored in fifo's bank 1.
444 6042e?atarm?14-dec-06 at91sam7a3 preliminary when the device firmware has polled this bit or has been interr upted by this signal, it must transfer data from the fifo to microcontroller memory. the number of bytes received is available in rxbytecnt field. bank 1 fifo values are read through udp_ fdrx register. once a transfer is done, the de vice firmware must release bank 1 to the usb device by clearing rx_data_bk1. dir: transfer direction (only available for control endpoints) read/write 0 = allows data out transactio ns in the control data stage. 1 = enables data in transactions in the control data stage. refer to chapter 8.5.3 of the universal serial bus specification, rev. 2.0 for more information on the control data stage. this bit must be set before udp_ csrx/r xsetup is cleared at the end of the setu p stage. according to the request sent in the setup data packet, the data stage is either a device to host (dir = 1) or host to device (dir = 0) data transfer. it is not necessary to check this bit to reve rse direction for the status stage. eptype[2:0]: endpoint type dtgle: data toggle read-only 0 = identifies data0 packet. 1 = identifies data1 packet. refer to chapter 8 of the universal serial bus specification, rev. 2.0 for more information on data0, data1 packet definitions. epeds: endpoint enable disable read: 0 = endpoint disabled. 1 = endpoint enabled. write: 0 = disables endpoint. 1 = enables endpoint. rxbytecnt[10:0]: number of bytes available in the fifo read-only when the host sends a data packet to the device, the usb device stores the data in the fifo and notifies the microcontrol- ler. the microcontroller can lo ad the data from t he fifo by reading rxbytecent byte s in the udp_ fdrx register. read/write 000 control 001 isochronous out 101 isochronous in 010 bulk out 110 bulk in 011 interrupt out 111 interrupt in
445 6042e?atarm?14-dec-06 at91sam7a3 preliminary 33.6.11 udp fifo data register register name: udp_ fdrx [x = 0..5] access type: read/write fifo_data[7:0]: fifo data value the microcontroller can push or pop values in the fifo through this register. rxbytecnt in the corresponding udp_ csrx register is the num ber of bytes to be read from the fifo (sent by the host). the maximum number of bytes to write is fixed by the max packet size in the standard endpoint descriptor. it can not be more than the physical memory size associated to the endpoint. refer to the universal serial bus specification, rev. 2.0 for more information. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ?????? ?? 76543210 fifo_data
446 6042e?atarm?14-dec-06 at91sam7a3 preliminary 33.6.12 udp transceiver control register register name: udp_ txvc access type: read/write warning: the udp peripheral clock in the power management controller (pmc) must be enabled before any read/write operations to the udp registers including the udp_txcv register. txvdis: transceiver disable when udp is disabled, power consumption can be reduced significantly by disab ling the embedded transceiver. this can be done by setting txvdis field. to enable the transceiver, txvdis must be cleared. note : if the usb pullup is not connected on dp, the user should not write in any udp register other than the udp_ txvc register. this is because if dp and dm are floating at 0, or pulled down, then se0 is received by the device with the conse- quence of a usb reset. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ?????? ? txvdis 76543210 ?????? ??
447 6042e?atarm?14-dec-06 at91sam7a3 preliminary 34. multimedia card interface (mci) 34.1 overview the multimedia card interface (mci) supports the multimediacard (mmc) specification v2.2 and the sd memory card specification v1.0. the mci includes a command register, response registers, data registers, timeout counters and error detection logic that automatically handle the transmission of commands and, when required, the reception of the associated responses and data with a limited processor overhead. the mci supports stream, block and multi-block data read and write, and is compatible with the peripheral dma controller (pdc) channels, minimizing processor intervention for large buffer transfers. the mci operates at a rate of up to master clock divided by 2 and supports the interfacing of 1 slot(s). each slot may be used to interface with a multimediacard bus (up to 30 cards) or with a sd memory card. only one slot can be selected at a time (slots are multiplexed). a bit field in the sd card register performs this selection. the sd memory card communication is based on a 9-pin interface (clock, command, four data and three power lines) and the multimediacard on a 7-pin interface (clock, command, one data, three power lines and one reserved for future use). the sd memory card interface also supports multimediacard operations. the main differ- ences between sd and multimedia cards are the initialization process and the bus topology.
448 6042e?atarm?14-dec-06 at91sam7a3 preliminary 34.2 block diagram figure 34-1. block diagram 34.3 application block diagram figure 34-2. application block diagram mcda3 (1) mcda2 (1) mcda1 (1) mcda0 (1) mccda (1) mcck (1) mci interface interrupt control pdc mci interrupt pio apb bridge pmc mck apb 23456 17 mmc 23456 17 8 sdcard 9 physical layer mci interface application layer ex: file system, audio, security, etc.
449 6042e?atarm?14-dec-06 at91sam7a3 preliminary 34.4 pin name list note: 1. i: input, o: output, pp: push/pull, od: open drain. 34.5 product dependencies 34.5.1 i/o lines the pins used for interfacing the multimedia cards or sd cards may be multiplexed with pio lines. the programmer must first program the pio controllers to assign the peripheral func- tions to mci pins. 34.5.2 power management the mci may be clocked through the power management controller (pmc), so the program- mer must first configure the pmc to enable the mci clock. 34.5.3 interrupt the mci interface has an interrupt line connected to the advanced interrupt controller (aic). handling the mci interrupt requires programming the aic before configuring the mci. 34.6 bus topology figure 34-3. multimedia memory card bus topology table 34-1. i/o lines description pin name pin description type (1) comments mccda command/response i/o/pp/od cmd of an mmc or sd card mcck clock i/o clk of an mmc or sd card mcda0 - mcda3 data 0..3 of slot a i/o/pp dat0 of an mmc dat[0..3] of an sd card 23456 17 mmc
450 6042e?atarm?14-dec-06 at91sam7a3 preliminary the multimedia card communication is based on a 7-pin serial bus interface. it has three com- munication lines and four supply lines. note: 1. i: input, o: output, pp: push/pull, od: open drain. figure 34-4. mmc bus connections (one slot) figure 34-5. sd memory card bus topology the sd memory card bus includes the signals listed in table 34-3 . table 34-2. bus topology pin number name type (1) description mci pin name (slot z) 1 rsv nc not connected - 2 cmd i/o/pp/od command/response mccdz 3 vss1 s supply voltage ground vss 4 vdd s supply voltage vdd 5 clk i/o clock mcck 6 vss2 s supply voltage ground vss 7 dat[0] i/o/pp data 0 mcdz0 23456 1 7 23456 1 7 23456 17 mccda mcda0 mcck mmc1 mmc2 mmc3 mci 23456 17 8 sd card 9
451 6042e?atarm?14-dec-06 at91sam7a3 preliminary note: 1. i: input, o: output, pp: push pull, od: open drain. figure 34-6. sd card bus connections with one slot when the mci is configured to operate with sd me mory cards, the width of the data bus can be selected in the mci_sdcr register. clearing th e sdcbus bit in this register means that the width is one bit; setting it means that the width is four bits. in the ca se of multimedia cards, only the data line 0 is used. the other data lines can be used as independent pios. 34.7 multimedia card operations after a power-on reset, the cards are initialized by a special message-based multimedia card bus protocol. each message is represented by one of the following tokens: command: a command is a token that starts an operation. a command is sent from the host either to a single card (addressed command) or to all connected cards (broadcast command). a command is transferred serially on the cmd line. response: a response is a token which is s ent from an addressed card or (synchronously) from all connected cards to the host as an answer to a previously received command. a response is transferred serially on the cmd line. data: data can be transferred from the card to the host or vice versa. data is transferred via the data line. card addressing is implemented using a sessi on address assigned during the initialization phase by the bus controller to all currently c onnected cards. their unique cid number identi- fies individual cards. table 34-3. sd memory card bus signals pin number name type (1) description mci pin name (slot z) 1 cd/dat[3] i/o/pp card detect/ data line bit 3 mcdz3 2 cmd pp command/response mccdz 3 vss1 s supply voltage ground vss 4 vdd s supply voltage vdd 5 clk i/o clock mcck 6 vss2 s supply voltage ground vss 7 dat[0] i/o/pp data line bit 0 mcdz0 8 dat[1] i/o/pp data line bit 1 mcdz1 9 dat[2] i/o/pp data line bit 2 mcdz2 23456 17 mcda0 - mcda3 mccda mcck 8 sd card 9
452 6042e?atarm?14-dec-06 at91sam7a3 preliminary the structure of commands, responses and data blocks is described in the multimedia-card system specification. see also table 34-4 on page 452 . multimediacard bus data transfers are composed of these tokens. there are different types of operations. addressed operations always contain a command and a response token. in addition, some operations have a data token; the others transfer their information directly within the command or response structure. in this case, no data token is present in an operation. the bits on the dat and the cmd lines are transferred synchronous to the clock mci clock. two types of data transfer commands are defined: sequential commands: these commands initiate a continuous data stream. they are terminated only when a stop command follows on the cmd line. this mode reduces the command overhead to an absolute minimum. block-oriented commands: th ese commands send a data block succeeded by crc bits. both read and write operations allow either single or multiple block transmission. a multiple block transmission is terminated when a stop command follows on the cmd line similarly to the sequential read. the mci provides a set of registers to perform the entire range of multimedia card operations. 34.7.1 command - response operation after reset, the mci is disabled and becomes valid after setting the mcien bit in the mci_cr control register. the pwsen bit saves power by dividing the mci clock by 2 pwsdiv + 1 when the bus is inactive. the command and the response of the card are clocked out with the rising edge of the mci clock. all the timings for multimedia card are defined in the multim ediacard system specification. the two bus modes (open drain and push/pull) needed to process all the operations are defined in the mci command register. the mci_cmdr allows a command to be carried out. for example, to perform an all_send_cid command: the command all_send_cid and the fields and values for the mci_cmdr control register are described in table 34-4 and table 34-5 . note: 1. bcr means broadcast command with response.. host command n id cycles cid cmd s t content crc e z ****** z s t content z z z table 34-4. all_send_cid command description cmd index type argument resp abbreviation command description cmd2 bcr (1) [31:0] stuff bits r2 all_send_cid asks all cards to send their cid numbers on the cmd line
453 6042e?atarm?14-dec-06 at91sam7a3 preliminary the mci_argr contains the argument field of the command. to send a command, the user must perform the following steps: fill the argument regi ster (mci_argr) with the command argument. set the command register (mci_cmdr) (see table 34-5 ). the command is sent immediately after writ ing the command register. the status bit cmdrdy in the status register (mci_sr) is asserted when the command is completed. if the command requires a response, it can be read in the mci response register (mci_rspr). the response size can be from 48 bits up to 136 bits depending on the command. the mci embeds an error detection to prevent any corrupted data during the transfer. the following flowchart shows how to send a command to the card and read the response if needed. in this example, the status register bits are polled but setting the appropriate bits in the interrupt enable register (mci_ier) allows using an interrupt method. table 34-5. fields and values for mci_cmdr command register field value cmdnb (command number) 2 (cmd2) rsptyp (response type) 2 (r2: 136 bits response) spcmd (special command) 0 (not a special command) opcmd (open drain command) 1 maxlat (max latency for command to response) 0 (nid cycles ==> 5 cycles) trcmd (transfer command) 0 (no transfer) trdir (transfer direction) x (available only in transfer command) trtyp (transfer type) x (available only in transfer command)
454 6042e?atarm?14-dec-06 at91sam7a3 preliminary figure 34-7. command/response functional flow diagram note: 1. if the command is send_op_cond, the crc error flag is always present (refer to r3 response in the multimedi a card specification). 34.7.2 data transfer operation the multimedia card allows seve ral read/write operations (single block, multiple blocks, stream, etc.). these kind of transfers can be selected setting the transfer type (trtyp) field in the mci command register (mci_cmdr). these operations can be done using the features of the peripheral dma controller (pdc). if the pdcmode bit is set in mci_mr, then al l reads and writes us e the pdc facilities. in all cases, the block length (blklen field) must be defined in the mode register mci_mr. this field determines the size of the data block. 34.7.3 read operation the following flowchart shows how to read a single block with or without use of pdc facilities. in this example (see figure 34-8 ), a polling method is used to wait for the end of read. simi- return ok return error (1) set the command argument mci_argr = argument (1) set the command mci_cmdr = command read mci_sr cmdrdy status error flags? read response if required ye s wait for command ready status flag check error bits in the status register (1) 0 1
455 6042e?atarm?14-dec-06 at91sam7a3 preliminary larly, the user can configure the interrupt enable register (mci_ier) to trigger an interrupt at the end of read. figure 34-8. read functional flow diagram note: 1. it is assumed that this command has been correctly sent (see figure 34-7 ). read status register mci_sr send select/deselect_card command (1) to select the card send set_blocklen command (1) read with pdc reset the pdcmode bit mci_mr &= ~pdcmode set the block length (in bytes) mci_mr |= (blocklenght <<16) number of words to read = 0 ? poll the bit rxrdy = 0? read data = mci_rdr number of words to read = number of words to read -1 send read_single_block command (1) yes set the pdcmode bit mci_mr |= pdcmode set the block length (in bytes) mci_mr |= (blocklength << 16) configure the pdc channel mci_rpr = data buffer address mci_rcr = blocklength/4 mci_ptcr = rxten send read_single_block command (1) read status register mci_sr poll the bit endrx = 0? yes return return yes no no no yes no number of words to read = blocklength/4
456 6042e?atarm?14-dec-06 at91sam7a3 preliminary 34.7.4 write operation in write operation, the mci mode register (mci_mr) is used to define the padding value when writing non-multiple block size. if the bit pd cpadv is 0, then 0x00 value is used when pad- ding data, otherwise 0xff is used. if set, the bit pdcmode enables pdc transfer. the following flowchart shows how to write a single block with or without use of pdc facilities (see figure 34-9 ). polling or interrup t method can be used to wait for the end of write accord- ing to the contents of the interrupt mask register (mci_imr).
457 6042e?atarm?14-dec-06 at91sam7a3 preliminary figure 34-9. write functional flow diagram note: 1. it is assumed that this command has been correctly sent (see figure 34-7 ). send select/deselect_card command (1) to select the card send set_blocklen command (1) write using pdc reset the pdcmode bit mci_mr &= ~pdcmode set the block length mci_mr |= (blocklenght <<16) send write_single_block command (1) set the pdcmode bit mci_mr |= pdcmode set the block length mci_mr |= (blocklength << 16) configure the pdc channel mci_tpr = data buffer address to write mci_tcr = blocklength/4 send write_single_block command (1) read status register mci_sr poll the bit notbusy= 0? yes return no yes no read status register mci_sr number of words to write = 0 ? poll the bit txrdy = 0? mci_tdr = data to write number of words to write = number of words to write -1 yes return no yes no number of words to write = blocklength/4 mci_ptcr = txten
458 6042e?atarm?14-dec-06 at91sam7a3 preliminary the following flowchart shows how to manage a mu ltiple write block transfer with the pdc (see figure 34-10 ). polling or interrupt method can be used to wait fo r the end of write accord- ing to the contents of the interrupt mask register (mci_imr). figure 34-10. multiple write functi onal flow diagram note: 1. it is assumed that this command has been correctly sent (see figure 34-7 ). send select/deselect_card command (1) to select the card send set_blocklen command (1) set the pdcmode bit mci_mr |= pdcmode set the block length mci_mr |= (blocklength << 16) configure the pdc channel mci_tpr = data buffer address to write mci_tcr = blocklength/4 send write_multiple_block command (1) read status register mci_sr poll the bit blke = 0? yes no mci_ptcr = txten poll the bit notbusy = 0? yes return no send stop_transmission command (1)
459 6042e?atarm?14-dec-06 at91sam7a3 preliminary 34.8 sd card operations the multimedia card interface allows processi ng of sd memory (secure digital memory card) card commands. sd cards are based on the multi media card (mmc ) format, but are physic ally slightly thicker and feature higher data transfer rates, a lock switch on the side to prevent accidental overwrit- ing and security features. the physical form fa ctor, pin assignment and data transfer protocol are forward-compatible with the multimedia card with some additions. sd is covered by numerous patents and trademarks, and licensing is only available through the secure digital card association. the sd card communication is based on a 9-pin interface (clock, command, 4 x data and 3 x power lines). the communication protocol is defi ned as a part of this specification. the main difference between the sd card and the mult imedia card is the initialization process. the sd card register (mci_sd cr) allows selection of the card slot and the data bus width. the sd card bus allows dynamic configuration of the number of data lines. after power up, by default, the sd card uses only dat0 for data transfer. after initialization, the host can change the bus width (number of active data lines).
460 6042e?atarm?14-dec-06 at91sam7a3 preliminary 34.9 multimedia card inte rface (mci) user interface note: 1. the response register can be read by n accesses at the same mci_rspr or at consecutive addresses (0x20 to 0x2c). n depends on the size of the response. table 34-6. register mapping offset register register name read/write reset 0x00 control register mci_cr write ? 0x04 mode register mci_mr read/write 0x0 0x08 data timeout register mci_dtor read/write 0x0 0x0c sd card register mci_sdcr read/write 0x0 0x10 argument register mci_argr read/write 0x0 0x14 command register mci_cmdr write ? 0x18 - 0x1c reserved ? ? ? 0x20 response register (1) mci_rspr read 0x0 0x24 response register (1) mci_rspr read 0x0 0x28 response register (1) mci_rspr read 0x0 0x2c response register (1) mci_rspr read 0x0 0x30 receive data register mci_rdr read 0x0 0x34 transmit data register mci_tdr write ? 0x38 - 0x3c reserved ? ? ? 0x40 status register mci_sr read 0xc0e5 0x44 interrupt enable register mci_ier write ? 0x48 interrupt disable register mci_idr write ? 0x4c interrupt mask register mci_imr read 0x0 0x50-0xfc reserved ? ? ? 0x100-0x124 reserved for the pdc ? ? ?
461 6042e?atarm?14-dec-06 at91sam7a3 preliminary 34.9.1 mci control register name: mci_cr access type: write-only mcien: multi-media interface enable 0 = no effect. 1 = enables the multi-media interface if mcdis is 0. mcidis: multi-media interface disable 0 = no effect. 1 = disables the multi-media interface. pwsen: power save mode enable 0 = no effect. 1 = enables the power saving mode if pwsdis is 0. warning: before enabling this mode, the user must set a value different from 0 in the pwsdiv field (mode register mci_mr). pwsdis: power save mode disable 0 = no effect. 1 = disables the power saving mode. swrst: software reset 0 = no effect. 1 = resets the mci. a software triggered hardware reset of the mci interface is performed. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ???????? 76543210 swrst ? ? ? pwsdis pwsen mcidis mcien
462 6042e?atarm?14-dec-06 at91sam7a3 preliminary 34.9.2 mci mode register name: mci_mr access type: read/write clkdiv: clock divider multimedia card interface clock (mcck or mci_ck) is master clock (mck) divided by (2*(clkdiv+1)). pwsdiv: power saving divider multimedia card interface clock is divided by 2 (pwsdiv) + 1 when entering power saving mode. warning: this value must be different from 0 before enabling the power save mode in the mci_cr (mci_pwsen bit). pdcpadv: pdc padding value 0 = 0x00 value is used when padding data in write transfer (not only pdc transfer). 1 = 0xff value is used when padding data in write transfer (not only pdc transfer). pdcmode: pdc-oriented mode 0 = disables pdc transfer 1 = enables pdc transfer. in this case, unre and ovre flags in the mci mode register (mci_sr) are deactivated after the pdc transfer has been completed. blklen: data block length this field determines the size of the data block. bits 16 and 17 must be set to 0 31 30 29 28 27 26 25 24 ? ? blklen 23 22 21 20 19 18 17 16 blklen 0 0 15 14 13 12 11 10 9 8 pdcmode pdcpadv ? ? ? pwsdiv 76543210 clkdiv
463 6042e?atarm?14-dec-06 at91sam7a3 preliminary 34.9.3 mci data timeout register name: mci_dtor access type: read/write dtocyc: data timeout cycle number dtomul: data timeout multiplier these fields determine the maximum number of master clock cycles that the mci waits between two data block transfers. it equals (dtocyc x multiplier). multiplier is defined by dtomul as shown in the following table: if the data time-out set by dtocyc and dtomul has been exceeded, the data time-out error flag (dtoe) in the mci status register (mci_sr) raises. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ???????? 76543210 ? dtomul dtocyc dtomul multiplier 0001 00116 010128 011256 1001024 1014096 1 1 0 65536 1 1 1 1048576
464 6042e?atarm?14-dec-06 at91sam7a3 preliminary 34.9.4 mci sdcard register name: mci_sdcr access type: read/write sdcsel: sdcard slot sdcbus: sdcard bus width 0 = 1-bit data bus 1 = 4-bit data bus 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ???????? 76543210 sdcbus????? sdcsel sdcsel sdcard slot 0 0 slot a is selected . 0 1 ? 1 0 ? 1 1 ?
465 6042e?atarm?14-dec-06 at91sam7a3 preliminary 34.9.5 mci argument register name: mci_argr access type: read/write arg: command argument 31 30 29 28 27 26 25 24 arg 23 22 21 20 19 18 17 16 arg 15 14 13 12 11 10 9 8 arg 76543210 arg
466 6042e?atarm?14-dec-06 at91sam7a3 preliminary 34.9.6 mci command register name: mci_cmdr access type: write-only this register is write-protecte d while cmdrdy is 0 in mci_sr. if an interrupt command is sen t, this register is only write- able by an interrupt response (field spcmd). this means that the current command execution cannot be interrupted or modified. cmdnb: command number rsptyp: response type spcmd: special command opdcmd: open drain command 0 = push pull command 1 = open drain command 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ? ? ? trtyp trdir trcmd 15 14 13 12 11 10 9 8 ? ? ? maxlat opdcmd spcmd 76543210 rsptyp cmdnb rsp response type 0 0 no response. 0 1 48-bit response. 1 0 136-bit response. 1 1 reserved. spcmd command 0 0 0 not a special cmd. 001 initialization cmd: 74 clock cycles for in itialization sequence. 010 synchronized cmd: wait for the end of the current data block transfer before sending the pending command. 011reserved. 100 interrupt command: corresponds to the interrupt mode (cmd40). 101 interrupt response: corresponds to the interrupt mode (cmd40).
467 6042e?atarm?14-dec-06 at91sam7a3 preliminary maxlat: max latency for command to response 0 = 5-cycle max latency 1 = 64-cycle max latency trcmd: transfer command trdir: transfer direction 0 = write 1 = read trtyp: transfer type trcmd transfer type 0 0 no data transfer 0 1 start data transfer 1 0 stop data transfer 11reserved trtyp transfer type 0 0 0 mmc/sdcard single block 0 0 1 mmc/sdcard multiple block 010mmc stream 0 1 1 reserved
468 6042e?atarm?14-dec-06 at91sam7a3 preliminary 34.9.7 mci response register name: mci_rspr access type: read-only rsp: response note: 1. the response register can be read by n accesses at the same mci_rspr or at consecutive addresses (0x20 to 0x2c). n depends on the size of the response. 34.9.8 mci receive data register name: mci_rdr access type: read-only data: data to read 34.9.9 mci transmit data register name: mci_tdr access type: write-only data: data to write 31 30 29 28 27 26 25 24 rsp 23 22 21 20 19 18 17 16 rsp 15 14 13 12 11 10 9 8 rsp 76543210 rsp 31 30 29 28 27 26 25 24 data 23 22 21 20 19 18 17 16 data 15 14 13 12 11 10 9 8 data 76543210 data 31 30 29 28 27 26 25 24 data 23 22 21 20 19 18 17 16 data 15 14 13 12 11 10 9 8 data 76543210 data
469 6042e?atarm?14-dec-06 at91sam7a3 preliminary 34.9.10 mci status register name: mci_sr access type: read-only cmdrdy: command ready 0 = a command is in progress. 1 = the last command has been sent. cleared when writing in the mci_cmdr. rxrdy: receiver ready 0 = data has not yet been received since the last read of mci_rdr. 1 = data has been received since the last read of mci_rdr. txrdy: transmit ready 0= the last data written in mci_tdr has not yet been transferred in the shift register. 1= the last data written in mci_tdr has been transferred in the shift register. blke: data block ended this flag must be used only for write operations. 0 = a data block transfer is not yet finished. cleared when reading the mci_sr. 1 = a data block transfer has ended, including the crc16 status transmission. in pdc mode (pdcmode=1), the flag is set when the crc status of the last block has been transmitted (txbufe already set). otherwise (pdcmode=0), the flag is set for each transmitted crc status. refer to the mmc or sd sp ecification for more details concerning the crc status. dtip: data transfer in progress 0 = no data transfer in progress. 1 = the current data tran sfer is still in progress, including crc16 calculatio n. cleared at the end of the crc16 calculation. notbusy: mci not busy this flag must be used only for write operations. a block write operation uses a simple busy signalling of the write operat ion duration on the data (d at0) line: during a data transfer block, if the card does not have a free data receive buffer, the card indicates this condition by pulling down the dat a line (dat0) to low. the card stops pulling down the data line as soon as at least one receive buffer for the defined data transfer block length becomes free. the notbusy flag allows to deal with these different states. 31 30 29 28 27 26 25 24 unreovre?????? 23 22 21 20 19 18 17 16 ? dtoe dcrce rtoe rende rcrce rdire rinde 15 14 13 12 11 10 9 8 txbuferxbuff?????? 76543210 endtx endrx notbusy dtip blke txrdy rxrdy cmdrdy
470 6042e?atarm?14-dec-06 at91sam7a3 preliminary 0 = the mci is not ready for new data transfer. cleared at the end of the card response. 1 = the mci is ready for new data transfer. set when the busy state on the data line has ended. this corresponds to a free internal data receive buffer of the card. refer to the mmc or sd specification for more details concerning the busy behavior. endrx: end of rx buffer 0 = the receive counter register has not reached 0 since the last write in mci_rcr or mci_rncr. 1 = the receive counter register has reached 0 since the last write in mci_rcr or mci_rncr. endtx: end of tx buffer 0 = the transmit counter register has not reached 0 since the last write in mci_tcr or mci_tncr. 1 = the transmit counter register has reached 0 since the last write in mci_tcr or mci_tncr. note: blke and notbusy flags can be used to check that the data has been successfully transmitted on the data lines and not only transferred from the pdc to the mci controller. rxbuff: rx buffer full 0 = mci_rcr or mci_rncr has a value other than 0. 1 = both mci_rcr and mci_rncr have a value of 0. txbufe: tx buffer empty 0 = mci_tcr or mci_tncr has a value other than 0. 1 = both mci_tcr and mci_tncr have a value of 0. note: blke and notbusy flags can be used to check that the data has been successfully transmitted on the data lines and not only transferred from the pdc to the mci controller. rinde: response index error 0 = no error. 1 = a mismatch is detected between the command index sent and the response index received. cleared when writing in the mci_cmdr. rdire: response direction error 0 = no error. 1 = the direction bit from card to host in the response has not been detected. rcrce: response crc error 0 = no error. 1 = a crc7 error has been detected in the response. cleared when writing in the mci_cmdr. rende: response end bit error 0 = no error. 1 = the end bit of the response has not been detected. cleared when writing in the mci_cmdr. rtoe: response time-out error 0 = no error. 1 = the response time-out set by maxlat in the mci_cmdr has been exceeded. cleared when writing in the mci_cmdr.
471 6042e?atarm?14-dec-06 at91sam7a3 preliminary dcrce: data crc error 0 = no error. 1 = a crc16 error has been detected in the last data block. cleared by reading in the mci_sr register. dtoe: data time-out error 0 = no error. 1 = the data time-out set by dtocyc and dtomul in mci_dtor has been exceeded. cleared by reading in the mci_sr register. ovre: overrun 0 = no error. 1 = at least one 8-bit received data has been lost (not read). cleared when sending a new data transfer command. unre: underrun 0 = no error. 1 = at least one 8-bit data has been sent without valid inform ation (not written). cleared when sending a new data transfer command. rxbuff: rx buffer full 0 = mci_rcr or mci_rncr has a value other than 0. 1 = both mci_rcr and mci_rncr have a value of 0. txbufe: tx buffer empty 0 = mci_tcr or mci_tncr has a value other than 0. 1 = both mci_tcr and mci_tncr have a value of 0.
472 6042e?atarm?14-dec-06 at91sam7a3 preliminary 34.9.11 mci interrupt enable register name: mci_ier access type: write-only cmdrdy: command ready interrupt enable rxrdy: receiver ready interrupt enable txrdy: transmit ready interrupt enable blke: data block ended interrupt enable dtip: data transfer in progress interrupt enable notbusy: data not busy interrupt enable endrx: end of receive buffer interrupt enable endtx: end of transmit buffer interrupt enable rxbuff: receive buffer full interrupt enable txbufe: transmit buffer empty interrupt enable rinde: response index error interrupt enable rdire: response direction error interrupt enable rcrce: response crc error interrupt enable rende: response end bit error interrupt enable rtoe: response time-out error interrupt enable dcrce: data crc error interrupt enable dtoe: data time-out error interrupt enable ovre: overrun interrupt enable unre: underrun interrupt enable 0 = no effect. 1 = enables the corresponding interrupt. 31 30 29 28 27 26 25 24 unreovre?????? 23 22 21 20 19 18 17 16 ? dtoe dcrce rtoe rende rcrce rdire rinde 15 14 13 12 11 10 9 8 txbuferxbuff?????? 76543210 endtx endrx notbusy dtip blke txrdy rxrdy cmdrdy
473 6042e?atarm?14-dec-06 at91sam7a3 preliminary 34.9.12 mci interrupt disable register name: mci_idr access type: write-only cmdrdy: command ready interrupt disable rxrdy: receiver ready interrupt disable txrdy: transmit ready interrupt disable blke: data block ended interrupt disable dtip: data transfer in progress interrupt disable notbusy: data not busy interrupt disable endrx: end of receive buffer interrupt disable endtx: end of transmit buffer interrupt disable rxbuff: receive buffer full interrupt disable txbufe: transmit buffer empty interrupt disable rinde: response index error interrupt disable rdire: response direction error interrupt disable rcrce: response crc error interrupt disable rende: response end bit error interrupt disable rtoe: response time-out error interrupt disable dcrce: data crc error interrupt disable dtoe: data time-out error interrupt disable ovre: overrun interrupt disable unre: underrun interrupt disable 0 = no effect. 1 = disables the corresponding interrupt. 31 30 29 28 27 26 25 24 unreovre?????? 23 22 21 20 19 18 17 16 ? dtoe dcrce rtoe rende rcrce rdire rinde 15 14 13 12 11 10 9 8 txbuferxbuff?????? 76543210 endtx endrx notbusy dtip blke txrdy rxrdy cmdrdy
474 6042e?atarm?14-dec-06 at91sam7a3 preliminary 34.9.13 mci interrupt mask register name: mci_imr access type: read-only cmdrdy: command ready interrupt mask rxrdy: receiver ready interrupt mask txrdy: transmit ready interrupt mask blke: data block ended interrupt mask dtip: data transfer in progress interrupt mask notbusy: data not busy interrupt mask endrx: end of receive buffer interrupt mask endtx: end of transmit buffer interrupt mask rxbuff: receive buffer full interrupt mask txbufe: transmit buffer empty interrupt mask rinde: response index error interrupt mask rdire: response direction error interrupt mask rcrce: response crc error interrupt mask rende: response end bit error interrupt mask rtoe: response time-out error interrupt mask dcrce: data crc error interrupt mask dtoe: data time-out error interrupt mask ovre: overrun interrupt mask unre: underrun interrupt mask 0 = the corresponding interrupt is not enabled. 1 = the corresponding interrupt is enabled. 31 30 29 28 27 26 25 24 unreovre?????? 23 22 21 20 19 18 17 16 ? dtoe dcrce rtoe rende rcrce rdire rinde 15 14 13 12 11 10 9 8 txbuferxbuff?????? 76543210 endtx endrx notbusy dtip blke txrdy rxrdy cmdrdy
475 6042e?atarm?14-dec-06 at91sam7a3 preliminary 35. analog-to-digital converter (adc) 35.1 overview the adc is based on a successive approximation register (sar) 10-bit analog-to-digital converter (adc). it also integrates an 8-to-1 analog multiplexer, making possible the analog- to-digital conversions of 8 analog lines. the conversions extend from 0v to advref. the adc supports an 8-bit or 10-bit resolution mode, and conversion results are reported in a common register for all channels, as well as in a channel-dedicated register. software trigger, external trigger on rising edge of the adtrg pin or internal triggers from timer counter out- put(s) are configurable. the adc also integrates a sleep mode and a conversion sequencer and connects with a pdc channel. these features reduce both power consumption and processor intervention. finally, the user can configure adc timings, such as startup time and sample & hold time. 35.2 block diagram figure 35-1. analog-to-digital conv erter block diagram adc interrupt adc adtrg vddana advref gnd trigger selection control logic successive approximation register analog-to-digital converter timer counter channels user interface aic peripheral bridge apb pdc asb dedicated analog inputs analog inputs multiplexed with i/o lines ad- ad- ad- pio ad- ad- ad-
476 6042e?atarm?14-dec-06 at91sam7a3 preliminary 35.3 signal description 35.4 product dependencies 35.4.1 power management the adc is automatically clocked after the firs t conversion in normal mode. in sleep mode, the adc clock is automatically stopped after each conversion. as the logic is small and the adc cell can be put into sleep mode, the power management controller has no effect on the adc behavior. 35.4.2 interrupt sources the adc interrupt line is connected on one of the internal sources of the advanced interrupt controller. using the adc interrupt requ ires the aic to be programmed first. 35.4.3 analog inputs the analog input pins can be multiplexed with p io lines. in this case, the assignment of the adc input is automatically done as soon as the corresponding channel is enabled by writing the register adc_cher. by default , after reset, the pio line is co nfigured as input with its pull- up enabled and the adc input is connected to the gnd. 35.4.4 i/o lines the pin adtrg may be shared with other peripheral functions through the pio controller. in this case, the pio controller should be set accordingly to assign the pin adtrg to the adc function. 35.4.5 timer triggers timer counters may or may not be used as hardware triggers depending on user require- ments. thus, some or all of the timer counters may be non-connected. 35.4.6 conversion performances for performance and electrical characteristics of the adc, see the dc characteristics section. table 35-1. adc pin description pin name description vddana analog power supply advref reference voltage ad0 - ad 7 analog input channels adtrg external trigger
477 6042e?atarm?14-dec-06 at91sam7a3 preliminary 35.5 functional description 35.5.1 analog-to-digital conversion the adc uses the adc clock to perform conv ersions. converting a single analog value to a 10-bit digital data requires sample and hold clock cycles as defined in the field shtim of the ?adc mode register? on page 484 and 10 adc clock cycles. the adc clock frequency is selected in the prescal field of the mode register (adc_mr). the adc clock range is between mck/2, if prescal is 0, and mck/128, if prescal is set to 63 (0x3f). prescal must be programmed in order to provide an adc clock frequency according to the parameters given in the product definition section. 35.5.2 conversion reference the conversion is performed on a full range between 0v and the reference voltage pin advref. analog inputs between these voltages convert to values based on a linear conversion. 35.5.3 conversion resolution the adc supports 8-bit or 10-bit resolutions. the 8-bit selection is performed by setting the bit lowres in the adc mode register (adc_mr). by default, after a reset, the resolution is the highest and the data field in the data registers is fully used. by setting the bit lowres, the adc switches in the lowest resolution and the conversion results can be read in the eight low- est significant bits of the data registers. th e two highest bits of the data field in the corresponding adc_cdr register and of the ldata field in the adc_lcdr register read 0. moreover, when a pdc channel is connected to the adc, 10-bit resolution sets the transfer request sizes to 16-bit. setting the bit lowres automatically switches to 8-bit data transfers. in this case, the destination buffers are optimized.
478 6042e?atarm?14-dec-06 at91sam7a3 preliminary 35.5.4 conversion results when a conversion is completed, the resulting 10-bit digital value is stored in the channel data register (adc_cdr) of the current chan nel and in the adc last converted data regis- ter (adc_lcdr). the channel eoc bit in the status register (adc_sr) is set and the drdy is set. in the case of a connected pdc channel, drdy rising triggers a data transfer request. in any case, either eoc and drdy can trigger an interrupt. reading one of the adc_cdr re gisters clears the corres ponding eoc bit. reading adc_lcdr clears the drdy bit and the eoc bit corresponding to the last converted channel. figure 35-2. eocx and drdy flag behavior conversion time read the adc_cdrx eocx drdy read the adc_lcdr chx (adc_chsr) (adc_sr) (adc_sr) write the adc_cr with start = 1 conversion time write the adc_cr with start = 1
479 6042e?atarm?14-dec-06 at91sam7a3 preliminary if the adc_cdr is not read before further incoming data is converted, the corresponding overrun error (ovre) flag is set in the status register (adc_sr). in the same way, new data converted when drdy is high sets the bit govre (general over- run error) in adc_sr. the ovre and govre flags are automatically cleared when adc_sr is read. figure 35-3. govre and ovrex flag behavior warning: if the corresponding channel is disabled during a conversion or if it is disabled and then reenabled during a conversion, its associated data and its corresponding eoc and ovre flags in adc_sr are unpredictable. eoc0 govre ch0 (adc_chsr) (adc_sr) (adc_sr) adtrg eoc1 ch1 (adc_chsr) (adc_sr) ovre0 (adc_sr) undefined data data a data b adc_lcdr undefined data data a adc_cdr0 undefined data data b adc_cdr1 data c data c conversion conversion read adc_sr drdy (adc_sr) read adc_cdr1 read adc_cdr0 conversion
480 6042e?atarm?14-dec-06 at91sam7a3 preliminary 35.5.5 conversion triggers conversions of the active analog channels are started with a software or a hardware trigger. the software trigger is provided by writing the control register (adc_cr) with the bit start at 1. the hardware trigger can be one of the tioa outputs of the timer counter channels, or the external trigger input of the adc (adtrg). the hardware trigger is selected with the field trgsel in the mode register (adc_mr). the se lected hardware trigger is enabled with the bit trgen in the mode register (adc_mr). if a hardware trigger is selected, the start of a conversion is detected at each rising edge of the selected signal. if one of the tioa outputs is selected, the corresponding timer counter chan- nel must be programmed in waveform mode. only one start command is necessary to initia te a conversion sequence on all the channels. the adc hardware logic automatically performs th e conversions on the active channels, then waits for a new request. the channel en able (adc_cher) and channel disable (adc_chdr) registers enable the analog channels to be enabled or disabled independently. if the adc is used with a pdc, only the transfers of converted data from enabled channels are performed and the resulting data buffers should be interpreted accordingly. warning: enabling hardware triggers does not disable the software trigger functionality. thus, if a hardware trigger is selected, the start of a conversion can be initiated either by the hard- ware or the so ftware trigger. 35.5.6 sleep mode and conversion sequencer the adc sleep mode maximizes power saving by automatically deactivating the adc when it is not being used for conversions. sleep mode is selected by setting the bit sleep in the mode register adc_mr. the sleep mode is automat ically managed by a conversion sequencer, whic h can automati- cally process the conversions of all channels at lowest power consumption. when a start conversion request occurs, the adc is automatically activated. as the analog cell requires a start-up time, the logic waits during this time and starts the conversion on the enabled channels. when all conversions are complete, the adc is deactivated until the next trigger. triggers occurring during the sequence are not taken into account. the conversion sequencer allows automatic processing with minimum processor intervention and optimized power consumption. conversion sequences can be performed periodically using a timer/counter output. the periodic acqu isition of several samples can be processed automatically without any intervention of the processor thanks to the pdc. note: the reference voltage pins always remain connected in normal mode as in sleep mode.
481 6042e?atarm?14-dec-06 at91sam7a3 preliminary 35.5.7 adc timings each adc has its own minimal startup time that is programmed through the field startup in the mode register adc_mr. in the same way, a minimal sample and hold time is necessary for the adc to guarantee the best converted final value between two channels selection. this time has to be programmed through the bitfield shtim in the mode register adc_mr. warning: no input buffer amplifier to isolate the source is included in the adc. this must be taken into consideration to program a precise value in the shtim field. see the section adc characteristics in the product datasheet.
482 6042e?atarm?14-dec-06 at91sam7a3 preliminary 35.6 analog-to-digital con verter (adc) user interface table 35-2. adc register mapping offset register name access reset state 0x00 control register adc_cr write-only ? 0x04 mode register adc_mr read/write 0x00000000 0x08 reserved ? ? ? 0x0c reserved ? ? ? 0x10 channel enable register adc_cher write-only ? 0x14 channel disable register adc_chdr write-only ? 0x18 channel status register adc_chsr read-only 0x00000000 0x1c status register adc_sr read-only 0x000c0000 0x20 last converted data regi ster adc_lcdr read-only 0x00000000 0x24 interrupt enable register adc_ier write-only ? 0x28 interrupt disable register adc_idr write-only ? 0x2c interrupt mask register adc_imr read-only 0x00000000 0x30 channel data register 0 adc_cdr0 read-only 0x00000000 0x34 channel data register 1 adc_cdr1 read-only 0x00000000 ... ... ... ... ... 0x4c channel data register 7 adc_cdr7 read-only 0x00000000 0x50 - 0xfc reserved ? ? ?
483 6042e?atarm?14-dec-06 at91sam7a3 preliminary 35.6.1 adc control register register name: adc_cr access type: write-only swrst: software reset 0 = no effect. 1 = resets the adc simulating a hardware reset. start: start conversion 0 = no effect. 1 = begins analog-to-digital conversion. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ???????? 76543210 ?????? start swrst
484 6042e?atarm?14-dec-06 at91sam7a3 preliminary 35.6.2 adc mode register register name: adc_mr access type: read/write trgen: trigger enable trgsel: trigger selection lowres: resolution sleep: sleep mode 31 30 29 28 27 26 25 24 ???? shtim 23 22 21 20 19 18 17 16 ? ? ? startup 15 14 13 12 11 10 9 8 ?? prescal 76543210 ? ? sleep lowres trgsel trgen trgen selected trgen 0 hardware triggers are disabled. starting a conversion is only possible by software. 1 hardware trigger selected by trgsel field is enabled. trgsel selected trgsel 0 0 0 tioa ouput of the timer counter channel 0 0 0 1 tioa ouput of the timer counter channel 1 0 1 0 tioa ouput of the timer counter channel 2 0 1 1 tioa ouput of the timer counter channel 3 1 0 0 tioa ouput of the timer counter channel 4 1 0 1 tioa ouput of the timer counter channel 5 1 1 0 external trigger 111reserved lowres selected resolution 0 10-bit resolution 1 8-bit resolution sleep selected mode 0 normal mode 1 sleep mode
485 6042e?atarm?14-dec-06 at91sam7a3 preliminary prescal: prescaler rate selection adcclock = mck / ( (prescal+1) * 2 ) startup: start up time startup time = (startup+1) * 8 / adcclock shtim: sample & hold time sample & hold time = (shtim+1) / adcclock
486 6042e?atarm?14-dec-06 at91sam7a3 preliminary 35.6.3 adc channel enable register register name: adc_cher access type: write-only chx: channel x enable 0 = no effect. 1 = enables the corresponding channel. 35.6.4 adc channel disable register register name: adc_chdr access type: write-only chx: channel x disable 0 = no effect. 1 = disables the corresponding channel. warning: if the corresponding channel is disabled during a conversion or if it is disabled then reenabled during a conver- sion, its associated data and its corresponding eoc and ovre flags in adc_sr are unpredictable. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ???????? 76543210 ch7 ch6 ch5 ch4 ch3 ch2 ch1 ch0 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ???????? 76543210 ch7 ch6 ch5 ch4 ch3 ch2 ch1 ch0
487 6042e?atarm?14-dec-06 at91sam7a3 preliminary 35.6.5 adc channel status register register name: adc_chsr access type: read-only chx: channel x status 0 = corresponding c hannel is disabled. 1 = corresponding channel is enabled. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ???????? 76543210 ch7 ch6 ch5 ch4 ch3 ch2 ch1 ch0
488 6042e?atarm?14-dec-06 at91sam7a3 preliminary 35.6.6 adc status register register name: adc_sr access type: read-only eocx: end of conversion x 0 = corresponding analog channel is disabl ed, or the conversion is not finished. 1 = corresponding analog channel is enabled and conversion is complete. ovrex: overrun error x 0 = no overrun error on the corresponding channel since the last read of adc_sr. 1 = there has been an overrun error on the corres ponding channel since the last read of adc_sr. drdy: data ready 0 = no data has been converted since the last read of adc_lcdr. 1 = at least one data has been conv erted and is ava ilable in adc_lcdr. govre: general overrun error 0 = no general overrun error occurred since the last read of adc_sr. 1 = at least one general overrun error has occurred since the last read of adc_sr. endrx: end of rx buffer 0 = the receive counter register has not reach ed 0 since the last write in adc_rcr or adc_rncr. 1 = the receive counter register has reached 0 since the last write in adc_rcr or adc_rncr. rxbuff: rx buffer full 0 = adc_rcr or adc_rncr ha ve a value other than 0. 1 = both adc_rcr and adc_rncr have a value of 0. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ????rxbuffendrxgovredrdy 15 14 13 12 11 10 9 8 ovre7 ovre6 ovre5 ovre4 ovre3 ovre2 ovre1 ovre0 76543210 eoc7 eoc6 eoc5 eoc4 eoc3 eoc2 eoc1 eoc0
489 6042e?atarm?14-dec-06 at91sam7a3 preliminary 35.6.7 adc last conv erted data register register name: adc_lcdr access type: read-only ldata: last data converted the analog-to-digital conversion data is pl aced into this register at the end of a conversion and remains until a new conver- sion is completed. 35.6.8 adc interrupt enable register register name: adc_ier access type: write-only eocx: end of conversion interrupt enable x ovrex: overrun error interrupt enable x drdy: data ready interrupt enable govre: general overrun error interrupt enable endrx: end of receive buffer interrupt enable rxbuff: receive buffer full interrupt enable 0 = no effect. 1 = enables the corresponding interrupt. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ?????? ldata 76543210 ldata 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ????rxbuffendrxgovredrdy 15 14 13 12 11 10 9 8 ovre7 ovre6 ovre5 ovre4 ovre3 ovre2 ovre1 ovre0 76543210 eoc7 eoc6 eoc5 eoc4 eoc3 eoc2 eoc1 eoc0
490 6042e?atarm?14-dec-06 at91sam7a3 preliminary 35.6.9 adc interrupt disable register register name: adc_idr access type: write-only eocx: end of conversion interrupt disable x ovrex: overrun error interrupt disable x drdy: data ready interrupt disable govre: general overrun error interrupt disable endrx: end of receive buffer interrupt disable rxbuff: receive buffer full interrupt disable 0 = no effect. 1 = disables the corresponding interrupt. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ????rxbuffendrxgovredrdy 15 14 13 12 11 10 9 8 ovre7 ovre6 ovre5 ovre4 ovre3 ovre2 ovre1 ovre0 76543210 eoc7 eoc6 eoc5 eoc4 eoc3 eoc2 eoc1 eoc0
491 6042e?atarm?14-dec-06 at91sam7a3 preliminary 35.6.10 adc interrupt mask register register name: adc_imr access type: read-only eocx: end of conversion interrupt mask x ovrex: overrun erro r interrupt mask x drdy: data ready interrupt mask govre: general overrun error interrupt mask endrx: end of receive buffer interrupt mask rxbuff: receive buffer full interrupt mask 0 = the corresponding interrupt is disabled. 1 = the corresponding interrupt is enabled. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ????rxbuffendrxgovredrdy 15 14 13 12 11 10 9 8 ovre7 ovre6 ovre5 ovre4 ovre3 ovre2 ovre1 ovre0 76543210 eoc7 eoc6 eoc5 eoc4 eoc3 eoc2 eoc1 eoc0
492 6042e?atarm?14-dec-06 at91sam7a3 preliminary 35.6.11 adc channel data register register name: adc_cdrx access type: read-only data: converted data the analog-to-digital conversion data is pl aced into this register at the end of a conversion and remains until a new conver- sion is completed. the convert data re gister (cdr) is only loaded if the corr esponding analog channel is enabled. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ?????? data 76543210 data
493 6042e?atarm?14-dec-06 at91sam7a3 preliminary 36. controller area network (can) 36.1 overview the can controller provides all the features required to implement the serial communication protocol can defined by robert bosch gmbh, the can specification as referred to by iso/11898a (2.0 part a and 2.0 part b) for high speeds and iso/11519-2 for low speeds. the can controller is able to handle all types of frames (data, remote, error and overload) and achieves a bitrate of 1 mbit/sec. can controller accesses are made through c onfiguration registers. 16 independent message objects (mailboxes) are implemented. any mailbox can be programmed as a reception buffer block (even non-consecutive buffers). for the reception of defined messages, one or several message objects can be masked with- out participating in the buffer feature. an interrupt is generated when the buffer is full. according to the mailbox configuration, the first message received can be locked in the can controller registers until the application acknowledg es it, or this message can be discarded by new received messages. any mailbox can be programmed for transmiss ion. several transmission mailboxes can be enabled in the same time. a priority can be defined for each mailbox independently. an internal 16-bit timer is used to stamp eac h received and sent message. this timer starts counting as soon as the can controller is enabl ed. this counter can be reset by the applica- tion or automatically after a reception in the last mailbox in time triggered mode. the can controller offers optimized features to support the time triggered communication (ttc) protocol.
494 6042e?atarm?14-dec-06 at91sam7a3 preliminary 36.2 block diagram figure 36-1. can block diagram 36.3 application block diagram figure 36-2. application block diagram internal bus can interrupt canrx controller area network pio cantx error counter user interface pmc mck mailbox priority encoder mb0 mbx (x = number of mailboxes - 1) control & status can protocol controller mb1 software software can controller transceiver implementatio n layers can-based application layer can-based profiles can data link layer can physical layer
495 6042e?atarm?14-dec-06 at91sam7a3 preliminary 36.4 i/o lines description 36.5 product dependencies 36.5.1 i/o lines the pins used for interfacing the can may be multiplexed with the pio lines. the programmer must first program the pio controller to assign the desired can pins to their peripheral func- tion. if i/o lines of the can are not used by the application, they can be used for other purposes by the pio controller. 36.5.2 power management the programmer must first enable the can clock in the power management controller (pmc) before using the can. a low-power mode is defined for the can contro ller: if the application does not require can operations, the can clock can be stopped when not needed and be restarted later. before stopping the clock, the can controller must be in low-power mode to complete the current transfer. after restarting the clock, the application must disable the low-power mode of the can controller. 36.5.3 interrupt the can interrupt line is connected on one of the internal sources of the advanced interrupt controller. using the can interrupt requires the aic to be programmed first. note that it is not recommended to use the can interrupt line in edge-sensitive mode. table 36-1. i/o lines description name description type canrx can receive serial data input cantx can transmit serial data output
496 6042e?atarm?14-dec-06 at91sam7a3 preliminary 36.6 can controller features 36.6.1 can protocol overview the controller area network (can) is a multi-master serial communication protocol that effi- ciently supports real-time control with a very high level of security with bit rates up to 1 mbit/s. the can protocol supports four different frame types: data frames: they carry data from a transmitter node to the receiver nodes. the overall maximum data frame length is 108 bits for a standard frame and 128 bits for an extended frame. remote frames: a destination node can request data from the source by sending a remote frame with an identifier that matches the identifier of the required data frame. the appropriate data source node then sends a data frame as a response to this node request. error frames: an error frame is generated by any node that detects a bus error. overload frames: they provide an extra delay between the preceding and the successive data frames or remote frames. the atmel can controller provides the cpu with full functionality of the can protocol v2.0 part a and v2.0 part b. it minimizes the cpu load in communication overhead. the data link layer and part of the physical layer are automatically handled by the can controller itself. the cpu reads or writes data or messages via the can controller mailboxes. an identifier is assigned to each mailbox. the can controller encapsulates or decodes data messages to build or to decode bus data frames. remote frames, error frames and overload frames are automatically handled by the can controller under supervision of the software application. 36.6.2 mailbox organization the can module has 16 buffers, also called chann els or mailboxes. an identifier that corre- sponds to the can identifier is defined for ea ch active mailbox. message identifiers can match the standard frame identifier or the extended frame identifier. this identifier is defined for the first time during the can initialization, but can be dynamically reconfigured later so that the mailbox can handle a new message family. severa l mailboxes can be configured with the same id. each mailbox can be configured in receive or in transmit mode independently. the mailbox object type is defined in the mot field of the can_mmrx register. 36.6.2.1 message acceptance procedure if the mide field in the can_midx register is set, the mailbox can handle the extended format identifier; otherwise, the mailbox handles the standard format identifier. once a new message is received, its id is masked with the can_mamx value and compared with the can_midx value. if accepted, the message id is copied to the can_midx register.
497 6042e?atarm?14-dec-06 at91sam7a3 preliminary figure 36-3. message acceptance procedure if a mailbox is dedicated to receiving several messages (a family of messages) with different ids, the acceptance mask defined in the can_ma mx register must mask the variable part of the id family. once a message is received, the application must decode the masked bits in the can_midx. to speed up the decoding, masked bits are grouped in the family id register (can_mfidx). for example, if the following message ids are handled by the same mailbox: id0 101000100100010010000100 0 11 00b id1 101000100100010010000100 0 11 01b id2 101000100100010010000100 0 11 10b id3 101000100100010010000100 0 11 11b id4 101000100100010010000100 1 11 00b id5 101000100100010010000100 1 11 01b id6 101000100100010010000100 1 11 10b id7 101000100100010010000100 1 11 11b the can_midx and can_mamx of mailbox x must be initialized to the corresponding values: can_midx = 001 101000100100010010000100 x 11 xxb can_mamx = 001 111111111111111111111111 0 11 00b if mailbox x receives a message with id6, then can_midx and can_mfidx are set: can_midx = 001 101000100100010010000100 1 11 10b can_mfidx = 00000000000000000000000000000110b if the application associates a handler for each message id, it may define an array of pointers to functions: void (*phandler[8])(void); when a message is received, the correspondi ng handler can be invoked using can_mfidx register and there is no need to check masked bits: unsigned int mfid0_register; mfid0_register = get_can_mfid0_register(); // get_can_mfid0_register() returns the value of the can_mfid0 register phandler[mfid0_register](); can_midx can_mamx message received & & == message accepted message refused no yes can_mfidx
498 6042e?atarm?14-dec-06 at91sam7a3 preliminary 36.6.2.2 receive mailbox when the can module receives a message, it look s for the first available mailbox with the low- est number and compares the received message id with the mailbox id. if such a mailbox is found, then the message is stored in its data registers. depending on the configuration, the mailbox is disabled as long as the message has not been acknowledged by the application (receive only), or, if new messages with the same id are received, then they overwrite the previous ones (receive with overwrite). it is also possible to configure a mailbox in consumer mode. in this mode, after each transfer request, a remote frame is automatically sent. the first answer received is stored in the corre- sponding mailbox data registers. several mailboxes can be chained to receive a buffer. they must be configured with the same id in receive mode, except for the last one, which can be configured in receive with over- write mode. the last mailbox can be used to detect a buffer overflow. 36.6.2.3 transmit mailbox when transmitting a message, the message length and data are written to the transmit mail- box with the correct identifier. for each transmit mailbox, a priority is assigned. the controller automatically sends the message with the highest priority first (set with the field prior in can_mmrx register). it is also possible to configure a mailbox in producer mode. in this mode, when a remote frame is received, the mailbox data are sent automatically. by enabling this mode, a producer can be done using only one mailbox instead of two: one to detect the remote frame and one to send the answer. table 36-2. mailbox object type description receive the first message received is st ored in mailbox data registers. data remain available until the next transfer request. receive with overwrite the last message received is stored in mailbox data regist er. the next message always overwrites the previous one. the application has to check whether a new message has not overwritten the current one while reading the data registers. consumer a remote frame is sent by the mailbox. the answer received is stored in mailbox data register. this extends receive mailbox features. data remain available until the next transfer request. table 36-3. mailbox object type description tr a n s m i t the message stored in the mailbox data registers will try to win the bus arbitration immediately or later according to or not the time management unit configuration (see section 36.6.3 ). the application is notified that the message has been sent or aborted. producer the message prepared in the mailbox data registers will be sent after receiving the next remote frame. this extends transmit mailbox features.
499 6042e?atarm?14-dec-06 at91sam7a3 preliminary 36.6.3 time management unit the can controller integrates a free-running 16-bit internal timer. the counter is driven by the bit clock of the can bus line. it is enabled wh en the can controller is enabled (canen set in the can_mr register). it is automatically cleared in the following cases: after a reset when the can controller is in low-power mode is enabled (lpm bit set in the can_mr and sleep bit set in the can_sr) after a reset of the can controller (canen bit in the can_mr register) in time-triggered mode, when a message is accepted by the last mailbox (rising edge of the mrdy signal in the can_msr last_mailbox_number register). the application can also reset the internal timer by setting timrst in the can_tcr register. the current value of the internal timer is always accessible by reading the can_tim register. when the timer rolls-over from ffffh to 0000h, tovf (timer overflow) signal in the can_sr register is set. tovf bit in the can_sr regist er is cleared by reading the can_sr register. depending on the corresponding interrupt mask in the can_imr register, an interrupt is gen- erated while tovf is set. in a can network, some can devi ces may have a larger counter. in this case, the application can also decide to freeze the internal counter when the timer reaches ffffh and to wait for a restart condition from another device. this feature is enabled by setting timfrz in the can_mr register. the can_tim register is frozen to the ffffh value. a clear condition described above restarts the timer. a time r overflow (tovf) interrupt is triggered. to monitor the can bus activity, the can_tim register is copied to the can _timestp regis- ter after each start of frame or end of frame and a tstp interrupt is triggered. if teof bit in the can_mr register is set, the value is captured at each end of frame, else it is captured at each start of frame. depending on the corresponding mask in the can_imr register, an interrupt is generated while tstp is set in th e can_sr. tstp bit is cleared by reading the can_sr register. the time management unit can operate in one of the two following modes: timestamping mode: the value of the internal timer is captured at each start of frame or each end of frame time triggered mode: a mailbox transfer operation is triggered when the internal timer reaches the mailbox trigger. timestamping mode is enabled by clearing ttm field in the can_mr register. time triggered mode is enabled by setting ttm field in the can_mr register.
500 6042e?atarm?14-dec-06 at91sam7a3 preliminary 36.6.4 can 2.0 standard features 36.6.4.1 can bit timing configuration all controllers on a can bus must have the same bit rate and bit length. at different clock fre- quencies of the individual controllers, the bit rate has to be adjusted by the time segments. the can protocol specification partitions the nominal bit time into four different segments: figure 36-4. partition of the can bit time time quantum: the time quantum (tq) is a fixed unit of time derived from the mck period. the total num- ber of time quanta in a bit time is programmable from 8 to 25. sync seg: synchronization segment. this part of the bit time is used to synchronize the various nodes on the bus. an edge is expected to lie within this segment. it is 1 tq long. prop seg: propagation segment. this part of the bit time is used to compensate for the physical delay times within the network. it is twice the sum of the signal?s propagation time on the bus line, the input comparator delay, and the output driver delay. it is programmable to be 1,2,..., 8 tq long. this parameter is defined in the propag field of the ?can baudrate register? . phase seg1, phase seg2: phase segment 1 and 2. the phase-buffer-segments are used to compensate for edge phase errors. these segments can be lengthened (phase seg1) or short ened (phase seg2) by resynchronization. phase segment 1 is programmable to be 1,2,..., 8 tq long. phase segment 2 length has to be at least as l ong as the information processing time (ipt) and may not be more than the length of phase segment 1. these parameters are defined in the phase1 and phase2 fields of the ?can baudrate register? . information processing time: the information processing time (ipt) is the time required for the logic to determine the bit level of a sampled bit. the ipt begins at the sample point, is measured in tq and is fixed at 2 tq for the atmel can . since phase segment 2 also begins at the sample point and is the last segment in the bit time, phase seg2 shall not be less than the ipt. sync_seg prop_seg phase_seg1 phase_seg2 nominal bit time sample point
501 6042e?atarm?14-dec-06 at91sam7a3 preliminary sample point: the sample point is the point in time at which the bus level is read and interpreted as the value of that resp ective bit. its lo cation is at the end of phase_seg1. sjw: resynchronization jump width. the resynchronization jump width defines the limit to the amount of lengthening or shorten- ing of the phase segments. sjw is programmable to be the minimum of phase seg1 and 4 tq. if the smp field in the can_br register is set, then the incoming bit stream is sampled three times with a period of half a can clock period, centered on sample point. in the can controller, the length of a bit on the can bus is determined by the parameters (brp, propag, phase1 and phase2). the time quantum is calculated as follows: note: the brp field must be within the range [1, 0x7f], i.e., brp = 0 is not authorized. to compensate for phase sh ifts between cloc k oscillators of different controllers on the bus, the can controller must resynchronize on any relevant signal edge of the current transmis- sion. the resynchronization shortens or lengt hens the bit time so that the position of the sample point is shifted with regard to the detected edge. the resynchronization jump width (sjw) defines the maximum of time by which a bit period may be shortened or lengthened by resynchronization. t bit t csc t prs t phs1 t phs2 ++ + = t csc brp 1 + () mck ? = t prs t csc propag 1 + () = t phs1 t csc phase1 1 + () = t phs2 t csc phase2 1 + () = t sjw t csc sjw 1 + () =
502 6042e?atarm?14-dec-06 at91sam7a3 preliminary figure 36-5. can bit timing example of bit timing determination for can baudrate of 500 kbit/s: mck = 48mhz can baudrate= 500kbit/s => bit time= 2us delay of the bus driver: 50 ns delay of the receiver: 30ns delay of the bus line (20m): 110ns the total number of time quanta in a bit time must be comprised between 8 and 25. if we fix the bit time to 16 time quanta: tcsc = 1 time quanta = bit time / 16 = 125 ns => brp = (tcsc x mck) - 1 = 5 the propagation segment time is equal to twice the sum of the signal?s propagation time on the bus line, the receiver delay and the output driver delay: tprs = 2 * (50+30+110) ns = 380 ns = 3 tcsc => propag = tprs/tcsc - 1 = 2 the remaining time for the two phase segments is: tphs1 + tphs2 = bit time - tcsc - tprs = (16 - 1 - 3)tcsc tphs1 + tphs2 = 12 tcsc because this number is even, we choose tphs2 = tphs1 (else we would choose tphs2 = tphs1 + tcsc) tphs1 = tphs2 = (12/2) tcsc = 6 tcsc => phase1 = phase2 = tphs1/tcsc - 1 = 5 the resynchronization jump width must be comprised between 1 tcsc and the minimum of 4 tcsc and tphs1. we choose its maximum value: tsjw = min(4 tcsc,tphs1) = 4 tcsc => sjw = tsjw/tcsc - 1 = 3 finally: can_br = 0x00053255 sync_ seg prop_seg phase_seg1 phase_seg2 nominal bit time sample point transmission point mck can clock t csc t prs t phs1 t phs2
503 6042e?atarm?14-dec-06 at91sam7a3 preliminary can bus synchronization two types of synchronization are distinguished: ?hard sy nchronization? at the start of a frame and ?resynchronization? inside a frame. after a hard synchronization, the bit time is restarted with the end of the sync_seg segment, regardless of the phase error. resynchronization causes a reduction or increase in the bit time so that the position of the sample point is shifted with respect to the detected edge. the effect of resynchronization is the same as that of hard synchronization when the magni- tude of the phase error of the edge causing the resyn chronization is less than or equal to the programmed value of the resynchronization jump width (t sjw ). when the magnitude of the phase error is larger than the resynchronization jump width and the phase error is pos itive, then phase_seg1 is lengthen ed by an amount equal to the resynchronizatio n jump width. the phase error is neg ative, then phase_seg2 is shorten ed by an amount equal to the resynchronizatio n jump width. figure 36-6. can resynchronization autobaud mode the autobaud feature is enabled by setting the abm field in the can_mr register. in this mode, the can controller is only listening to the line without acknowledging the received mes- sages. it can not send any message. the errors flags are updated. the bit timing can be adjusted until no error occurs (good configuration found). in this mode, the error counters are frozen. to go back to the standard mode, the abm bit must be cleared in the can_mr register. sync_ seg prop_seg phase_seg1 phase_seg2 sync_ seg prop_seg phase_seg1 phase_seg2 phase error phase error (max tsjw) sync_ seg sync_ seg sync_ seg prop_seg phase_seg1 phase_seg2 sync_ seg phase_seg2 sync_ seg prop_seg phase_seg1 phase_ seg2 sync_ seg phase_seg2 phase error nominal sample point sample point after resynchronization nominal sample point sample point after resynchronization the phase error is positive (the transmitter is slower than the receiver) received data bit received data bit nominal bit time (before resynchronization) bit time with resynchronization bit time with resynchronization phase error (max tsjw) nominal bit time (before resynchronization) the phase error is negative (the transmitter is faster than the receiver)
504 6042e?atarm?14-dec-06 at91sam7a3 preliminary 36.6.4.2 error detection there are five different error types that are not mutually exclusive. each error concerns only specific fields of the can data frame (refer to the bosch can specification for their correspondence): crc error (cerr bit in the can_sr register): with the crc, the transmitter calculates a checksum for the crc bit sequence from the start of frame bit until the end of the data field. this crc sequence is tr ansmitted in the crc field of the data or remote frame. bit-stuffing error (serr bit in the can_sr register): if a node detects a sixth consecutive equal bit level during the bit-stuffing area of a frame, it generates an error frame starting with the next bit-time. bit error (berr bit in can_sr register): a bit error occurs if a transmitter sends a dominant bit but detects a recessive bit on the bus line, or if it sends a recessive bit but detects a dominant bit on the bus line. an error frame is generated and starts with the next bit time. form error (ferr bit in the can_sr register): if a transmitter detects a dominant bit in one of the fix-formatted segments crc delimiter, ack delimiter or end of frame, a form error has occurred and an error frame is generated. acknowledgment error (aerr bit in the can_sr register): the transmitter checks the acknowledge slot, which is transmitted by the transmitting node as a recessive bit, contains a dominant bit. if this is the case, at least one other node has received the frame correctly. if not, an acknowledge error has occu rred and the transmitter will start in the next bit-time an error frame transmission. fault confinement to distinguish between temporary and permanent failures, every can controller has two error counters: rec (receive error counter) and tec (transmit error counter). the counters are incremented upon detected errors and respective ly are decremented upon correct transmis- sions or receptions. depending on the counter values, the state of the node changes: the initial state of the can controller is error active, meaning that the controller can send error active flags. the controller changes to the error passive state if there is an accumulation of errors. if the can controller fails or if there is an extreme accumulation of errors, there is a state transition to bus off. figure 36-7. line error mode error active error passive bus off tec > 255 init tec > 127 or rec > 127 tec < 127 and rec < 127 128 occurences of 11 consecutive recessive bits or can controller reset
505 6042e?atarm?14-dec-06 at91sam7a3 preliminary an error active unit takes part in bus communication and sends an active error frame when the can controller detects an error. an error passive unit cannot send an active error frame. it takes part in bus communication, but when an error is detected, a passive error frame is sent. also, after a transmission, an error passive unit waits before initiating furthe r transmission. a bus off unit is not allowed to have any influence on the bus. for fault confinement, two errors counters (tec and rec) are implemented. these counters are accessible via the can_ecr register. the state of the can controller is automatically updated according to these counter values. if the can controller is in error active state, then the erra bit is set in the can_sr register. the corresponding interrupt is pending while the interrupt is not masked in the can_imr register. if the can controller is in error passive mode, then the errp bit is set in the can_sr register and an interrupt remains pending while the errp bit is set in the can_imr register. if the can is in bus-off mode, then the boff bit is set in the can_sr r egister. as for errp and erra, an interrupt is pending while the boff bit is set in the can_imr register. when one of the error counters values exceeds 96, an increased error rate is indicated to the controller through the warn bit in can_sr register, but the node remains error active. the corresponding interrupt is p ending while the interrupt is set in the can_imr register. refer to the bosch can specification v2.0 for details on fault confinement. 36.6.4.3 overload the overload frame is provided to request a delay of the next data or remote frame by the receiver node (?request overload frame?) or to signal certain error conditions (?reactive over- load frame?) related to the intermission field respectively. reactive overload frames are transmitted after detection of the following error conditions: detection of a dominant bit during the first two bits of the intermission field detection of a dominant bit in the last bit of eof by a receiver, or detection of a dominant bit by a receiver or a transmitter at the last bit of an error or overload frame delimiter the can controller can generate a request overload frame automatically after each message sent to one of the can controller mailboxes. th is feature is enabled by setting the ovl bit in the can_mr register. reactive overload frames are automatically handled by the can controller even if the ovl bit in the can_mr register is not set. an overload flag is generated in the same way as an error flag, but error counters do not increment. 36.6.5 low-power mode in low-power mode, the can controller cannot send or receive messages. all mailboxes are inactive. in low-power mode, the sleep signal in the ca n_sr register is set; otherwise, the wakeup signal in the can_sr register is set. these tw o fields are exclusive except after a can con- troller reset (wakeup and sleep are stuck at 0 after a reset). after power-up reset, the low- power mode is disabled and the wa keup bit is set in the can_sr register only after detec- tion of 11 consecutive recessive bits on the bus.
506 6042e?atarm?14-dec-06 at91sam7a3 preliminary 36.6.5.1 enabling low-power mode a software application can enab le low-power mode by setting the lpm bit in the can_mr global register. the can controller enters low-power mode once all pending transmit mes- sages are sent. when the can controller enters low-power mode, the sleep si gnal in the ca n_sr register is set. depending on the corresponding mask in the can_imr register, an interrupt is gener- ated while sleep is set. the sleep signal in the can_sr register is automatically clea red once wakeup is set. the wakeup signal is automatically cleared once sleep is set. reception is disabled while the sleep signal is set to one in the can_sr register. it is impor- tant to note that those messages with higher priority than the last message transmitted can be received between the lpm command and entry in low-power mode. once in low-power mode, the can controller clock can be switched off by programming the chip?s power management controller (pmc). the can controller drains only the static current. error counters are disabled while the sleep signal is set to one. thus, to enter low-power mode, the software application must: ? set lpm field in the can_mr register ? wait for sleep signal rising now the can controller clock can be disabled. this is done by programming the power man- agement controller (pmc). figure 36-8. enabling low-power mode 36.6.5.2 disabling low-power mode the can controller can be awake after detecting a can bus activity. bus activity detection is done by an external module that may be embedded in the chip. when it is notified of a can bus activity, the software a pplication disables low-power mode by programming the can controller. sleep (can_sr) mrdy (can_msr1) lpm (can_mr) lpen= 1 can bus mrdy (can_msr3) mailbox 1 mailbox 3 arbitration lost wakeup (can_sr) 0x0 can_tim
507 6042e?atarm?14-dec-06 at91sam7a3 preliminary to disable low-power mode, the software application must: ? enable the can controller clock. this is done by programming the power management controller (pmc). ? clear the lpm field in the can_mr register the can controller synchronizes itself with the bus activity by checking for eleven consecutive ?recessive? bits. once synchronized, the wakeup signal in the can_sr register is set. depending on the corresponding mask in the can_imr register, an interrupt is generated while wakeup is set. the sleep signal in the can_sr register is automatically cleared once wakeup is set. wakeup signal is automatically cleare d once sleep is set. if no message is being sent on the bus, then the can controller is able to send a message eleven bit times after disabling low-power mode. if there is bus activity when low-power mode is disabled, the can controller is synchronized with the bus activity in the next interfra me. the previous message is lost (see figure 36-9 ). figure 36-9. disabling low-power mode sleep (can_sr) mrdy (can_msrx) lpm (can_mr) can bus bus activity detected message x interframe synchronization wakeup (can_sr) message lost
508 6042e?atarm?14-dec-06 at91sam7a3 preliminary 36.7 functional description 36.7.1 can controller initialization after power-up reset, the can controller is di sabled. the can controll er clock must be acti- vated by the power management controller (pmc) and the can controller interrupt line must be enabled by the interrupt controller (aic). the can controller must be initialized with the can network parameters. the can_br regis- ter defines the sampling point in the bit time period. can_br must be set before the can controller is enabled by setting the canen field in the can_mr register. the can controller is enabled by setting the canen flag in the can_mr register. at this stage, the internal can controller state machine is reset, error counters are reset to 0, error flags are reset to 0. once the can controller is enabled, bus sync hronization is done automatically by scanning eleven recessive bits. the wakeup bit in the can_ sr register is automa tically set to 1 when the can controller is synchronized (wakeup and sleep are stuck at 0 after a reset). the can controller can start listening to the network in autobaud mode. in this case, the error counters are locked and a mailbox may be configured in receive mode. by scanning error flags, the can_br register values synchron ized with the network. once no error has been detected, the application disables the autobaud mode, clearing the abm field in the can_mr register. figure 36-10. possible initialization procedure errors ? no yes (abm == 1 and canen == 1) canen = 1 (abm == 0) abm = 0 and canen = 0 (can_sr or can_msrx) change can_br value end of initialization configure a mailbox in reception mode enable can controller interrupt line enable can controller clock (aic) (pmc)
509 6042e?atarm?14-dec-06 at91sam7a3 preliminary 36.7.2 can controller interrupt handling there are two different types of interrupts. one type of interrupt is a message-object related interrupt, the other is a system interrupt that handles errors or system-related interrupt sources. all interrupt sources can be masked by writing the corresponding field in the can_idr regis- ter. they can be unmasked by writing to the can_ier register. after a power-up reset, all interrupt sources are disabled (masked). the current mask status can be checked by reading the can_imr register. the can_sr register gives all interrupt source states. the following events may initiate one of the two interrupts: message object interrupt ? data registers in the mailbox object are available to the application. in receive mode, a new message was received. in transmit mode, a message was transmitted successfully. ? a sent transmission was aborted. system interrupts ? bus-off interrupt: the can module enters the bus-off state. ? error-passive interrupt: the can module enters error passive mode. ? error-active mode: the can module is ne ither in error passive mode nor in bus- off mode. ? warn limit interrupt: the can module is in error-active mode, but at least one of its error counter value exceeds 96. ? wake-up interrupt: this interrupt is generated after a wake-up and a bus synchronization. ? sleep interrupt: this interrupt is generated after a low-power mode enable once all pending messages in transmission have been sent. ? internal timer counter overflow interrupt: this interrupt is generated when the internal timer rolls over. ? timestamp interrupt: this interrupt is generated after the reception or the transmission of a start of frame or an end of frame. the value of the internal counter is copied in the can_timestp register. all interrupts are cleared by clearing the interrupt source except for the internal timer counter overflow interrupt and the timestamp interrupt. these interrupts are cleared by reading the can_sr register.
510 6042e?atarm?14-dec-06 at91sam7a3 preliminary 36.7.3 can controller message handling 36.7.3.1 receive handling two modes are available to configure a mailbox to receive messages. in receive mode , the first message received is stored in the mailbox data register. in receive with overwrite mode , the last message received is stored in the mailbox. simple receive mailbox a mailbox is in receive mode once the mot field in the can_mmrx register has been config- ured. message id and message acceptance mask must be set before the receive mode is enabled. after receive mode is enabled, the mrdy flag in the can_msr register is automatically cleared until the first message is received. when the first message has been accepted by the mailbox, the mrdy flag is set. an interrupt is pending for the mailbox while the mrdy flag is set. this interrupt can be masked depending on the mailbox flag in the can_imr global register. message data are stored in the mailbox data register until the software application notifies that data processing has ended. this is done by aski ng for a new transfer command, setting the mtcr flag in the can_mcrx register. this automatically clears the mrdy signal. the mmi flag in the can_msrx register notifies the software that a message has been lost by the mailbox. this flag is set when messages are received while mrdy is set in the can_msrx register. this flag is cleared by reading the can_msrs register. a receive mail- box prevents from overwriting the first message by new ones while mrdy flag is set in the can_msrx register. see figure 36-11 . figure 36-11. receive mailbox note: in the case of arm architecture, can_msrx, can_mdlx, can_mdhx can be read using an optimized ldm assembler instruction. message 1 message 2 lost message 3 message 3 message 1 reading can_msrx reading can_mdhx & can_mdlx writing can_mcrx mmi (can_msrx) mrdy (can_msrx) can bus (can_mdlx can_mdhx) mtcr (can_mcrx) message id = can_midx
511 6042e?atarm?14-dec-06 at91sam7a3 preliminary receive with overwrite mailbox a mailbox is in receive with overwrite mode on ce the mot field in the can_mmrx register has been configured. message id and message acceptance masks must be set before receive mode is enabled. after receive mode is enabled, the mrdy flag in the can_msr register is automatically cleared until the first message is received. when the first message has been accepted by the mailbox, the mrdy flag is set. an interrupt is pending for the mailbox while the mrdy flag is set. this interrupt is masked depending on the mailbox flag in the can_imr global register. if a new message is received while the mrdy fl ag is set, this new message is stored in the mailbox data register, overwriting the previous message. the mmi flag in the can_msrx reg- ister notifies the software that a message has been dropped by the mailbox. this flag is cleared when reading the can_msrx register. the can controller may store a new message in the can data registers while the application reads them. to check that can_mdhx and can_ mdlx do not belong to different messages, the application must check the mmi field in the can_msrx register before and after reading can_mdhx and can_mdlx. if the mmi flag is set again after the data registers have been read, the software application has to re-read can_mdhx and can_mdlx (see figure 36-12 ). figure 36-12. receive with overwrite mailbox chaining mailboxes several mailboxes may be used to receive a buff er split into several messages with the same id. in this case, the mailbox with the lowest numb er is serviced first. in the receive and receive with overwrite modes, the field prior in the ca n_mmrx register has no effect. if mailbox 0 and mailbox 5 accept messages with the same id , the first message is received by mailbox 0 and the second message is received by mailbox 5. mailbox 0 must be configured in receive mode (i.e., the first message received is considered) and mailbox 5 must be configured in receive with overwrite mode. mailbox 0 cannot be configured in receive with overwrite mode; otherwise, all messages are accepted by this mailbox and mailbox 5 is never serviced. message 1 message 2 message 3 message 3 message 1 reading can_msrx reading can_mdhx & can_mdlx writing can_mcrx mmi (can_msrx) mrdy (can_msrx) can bus (can_mdlx can_mdhx) mtcr (can_mcrx) message id = can_midx message 4 message 2 message 4
512 6042e?atarm?14-dec-06 at91sam7a3 preliminary if several mailboxes are chained to receive a bu ffer split into several messages, all mailboxes except the last one (with the highest number) must be configured in receive mode. the first message received is handled by the first mailbox, the second one is refused by the first mail- box and accepted by the second mailbox, the last message is accepted by the last mailbox and refused by previous ones (see figure 36-13 ). figure 36-13. chaining three mailboxes to receive a buffer split into three messages if the number of mailboxes is not sufficient (the mmi flag of the last mailbox raises), the user must read each data received on the last mailbox in order to retrieve all the messages of the buffer split (see figure 36-14 ). mmi (can_msrx) mrdy (can_msrx) can bus message s1 reading can_msrx, can_msry and can_msrz writing mbx mby mbz in can_tcr reading can_mdh & can_mdl for mailboxes x, y and z mmi (can_msry) mrdy (can_msry) mmi (can_msrz) mrdy (can_msrz) message s2 message s3 buffer split in 3 messages
513 6042e?atarm?14-dec-06 at91sam7a3 preliminary figure 36-14. chaining three mailboxes to receive a buffer split into four messages 36.7.3.2 transmission handling a mailbox is in transmit mode once the mot field in the can_mmrx register has been con- figured. message id and message acceptance mask must be set before receive mode is enabled. after transmit mode is enabled, the mrdy flag in the can_msr register is automatically set until the first command is sent. when the mrdy flag is set, the software application can pre- pare a message to be sent by writing to the can_mdx registers. the message is sent once the software asks for a transfer command setting the mtcr bit and the message data length in the can_mcrx register. the mrdy flag remains at zero as long as the message has not been sent or aborted. it is important to note that no access to the mailbox data register is allowed while the mrdy flag is cleared. an interrupt is pending for the mailbox while the mrdy flag is set. this interrupt can be masked depending on the mailbox flag in the can_imr global register. it is also possible to send a remote frame sett ing the mrtr bit instead of setting the mdlc field. the answer to the remote frame is hand led by another reception mailbox. in this case, the device acts as a consumer but with the help of two mailboxes. it is possible to handle the remote frame emission and the answer reception using only one mailbox configured in con- sumer mode. refer to the section ?remote frame handling? on page 514 . several messages can try to win the bus arbitration in the same time. the message with the highest priority is sent first. several transfer request commands can be generated at the same time by setting mbx bits in the can_tcr register. the priority is set in the prior field of the can_mmrx register. priority 0 is the highest priority, priority 15 is the lowest priority. thus it is possible to use a part of the message id to se t the prior field. if two mailboxes have the same priority, the message of the mailbox with the lowest number is sent first. thus if mailbox mmi (can_msrx) mrdy (can_msrx) can bus message s1 reading can_msrx, can_msry and can_msrz writing mbx mby mbz in can_tcr reading can_mdh & can_mdl for mailboxes x, y and z mmi (can_msry) mrdy (can_msry) mmi (can_msrz) mrdy (can_msrz) message s2 message s3 buffer split in 4 messages message s4
514 6042e?atarm?14-dec-06 at91sam7a3 preliminary 0 and mailbox 5 have the same priority and have a message to send at the same time, then the message of the mailbox 0 is sent first. setting the macr bit in the can_mcrx regist er aborts the transmission. transmission for several mailboxes can be aborted by writing mbx fields in the can_ma cr register. if the message is being sent when the abort command is set, then the application is notified by the mrdy bit set and not the mabt in the can_msrx register. otherwise, if the message has not been sent, then the mrdy and the mabt are set in the can_msr register. when the bus arbitration is lost by a mailbox message, the can controller tries to win the next bus arbitration with the same message if this on e still has the highest prio rity. messages to be sent are re-tried automatically until they win the bus arbitration. this feature can be disabled by setting the bit drpt in the can_mr register. in this case if the me ssage was not sent the first time it was transmitted to the can transceiver, it is automatically aborted. the mabt flag is set in the can_msrx register until the next transfer command. figure 36-15 shows three mbx message attempts being made (mrdy of mbx set to 0). the first mbx message is sent, the second is aborted and the last one is trying to be aborted but too late because it has already been transmitted to the can transceiver. figure 36-15. transmitting messages 36.7.3.3 remote frame handling producer/consumer model is an efficient means of handling broadcasted messages. the push model allows a producer to broadcast messages; the pull model allows a customer to ask for messages. mtcr (can_mcrx) mrdy (can_msrx) can bus mbx message reading can_msrx writing can_mdhx & can_mdlx mbx message macr (can_mcrx) abort mbx message try to abort mbx message mabt (can_msrx)
515 6042e?atarm?14-dec-06 at91sam7a3 preliminary figure 36-16. producer / consumer model in pull mode, a consumer transmits a remote frame to the producer. when the producer receives a remote frame, it sends the answer accepted by one or many consumers. using transmit and receive mailboxes, a consumer must dedicate two mailboxes, one in transmit mode to send remote frames, and at least one in receive mode to capture the producer?s answer. the same structure is applicable to a producer: one reception mailbox is required to get the remote frame and one transmit mailbox to answer. mailboxes can be configured in producer or consumer mode. a lonely mailbox can handle the remote frame and the answer. with 16 mailboxes, the can controller can handle 16 indepen- dent producers/consumers. producer configuration a mailbox is in producer mode once the mot fi eld in the can_mmrx register has been con- figured. message id and message acceptance masks must be set before receive mode is enabled. after producer mode is enabled, the mrdy flag in the can_msr register is automatically set until the first transfer command. the software application prepares data to be sent by writing to the can_mdhx and the can_mdlx registers, then by setting the mtcr bit in the can_mcrx register. data is sent after the recept ion of a remote frame as soon as it wins the bus arbitration. the mrdy flag remains at zero as long as the message has not been sent or aborted. no access to the mailbox data register can be done while mrdy flag is cleared. an interrupt is pending for the mailbox wh ile the mrdy flag is set. this in terrupt can be masked according to the mailbox flag in the can_imr global register. if a remote frame is received while no data are ready to be sent (signal mrdy set in the can_msrx register), then the mmi signal is set in the can_msrx register. this bit is cleared by reading the can_msrx register. can data frame can remote frame can data frame indication(s) request request(s) indications response confirmation(s) push model pull model producer producer consumer consumer
516 6042e?atarm?14-dec-06 at91sam7a3 preliminary the mrtr field in the can_msrx register has no meaning. this field is used only when using receive and receive with overwrite modes. after a remote frame has been received, the mailbox functions like a transmit mailbox. the message with the highest priority is sent firs t. the transmitted message may be aborted by setting the macr bit in the can_mcr register. please refer to the section ?transmission handling? on page 513 . figure 36-17. producer handling consumer configuration a mailbox is in consumer mode once the mot field in the can_mmrx register has been con- figured. message id and message acceptance masks must be set before receive mode is enabled. after consumer mode is enabled, the mrdy flag in the can_msr register is automatically cleared until the first transfer request command. the software application sends a remote frame by setting the mtcr bit in the can_mcrx register or the mbx bit in the global can_tcr register. the application is notified of the answer by the mrdy flag set in the can_msrx register. the application can read the data contents in the can_mdhx and can_mdlx registers. an interrupt is pending for the mailbox while the mrdy flag is set. this interrupt can be masked according to the mailbox flag in the can_imr global register. the mrtr bit in the can_mcrx register has no effect. this field is used only when using transmit mode. after a remote frame has been sent, the consumer mailbox functions as a reception mailbox. the first message received is stored in the mailbox data registers. if other messages intended for this mailbox have been sent while the mrdy flag is set in the can_msrx register, they will be lost. the application is noti fied by reading the mmi field in the can_msrx register. the read operation automatically clears the mmi flag. if several messages are answered by the producer, the can controller may have one mailbox in consumer configuration, zero or several mailboxes in receive mode and one mailbox in receive with overwrite mode. in this case, the consumer mailbox must have a lower number than the receive with overwrite mailbox. the transfer command can be triggered for all mail- boxes at the same time by setting several mbx fields in the can_tcr register. mtcr (can_mcrx) mrdy (can_msrx) can bus remote frame message 1 message 1 message 2 (can_mdlx can_mdhx) mmi (can_msrx) remote frame remote frame message 2 reading can_msrx
517 6042e?atarm?14-dec-06 at91sam7a3 preliminary figure 36-18. consumer handling mtcr (can_mcrx) mrdy (can_msrx) can bus remote frame message x message y message y (can_mdlx can_mdhx) mmi (can_msrx) remote frame message x
518 6042e?atarm?14-dec-06 at91sam7a3 preliminary 36.7.4 can controller timing modes using the free running 16-bit internal timer, the can controller can be set in one of the two fol- lowing timing modes: timestamping mode: the value of the internal timer is captured at each start of frame or each end of frame. time triggered mode: the mailbox transfer operation is triggered when the internal timer reaches the mailbox trigger. timestamping mode is enabled by clearing the tt m bit in the can_mr register. time trig- gered mode is enabled by setting the ttm bit in the can_mr register. 36.7.4.1 timestamping mode each mailbox has its own timestamp value. each time a message is sent or received by a mailbox, the 16-bit value mtimestamp of the can_timestp register is transferred to the lsb bits of the can_msrx register. the value read in the can_msrx register corresponds to the internal timer value at the start of frame or the end of frame of the message handled by the mailbox. figure 36-19. mailbox timestamp 36.7.4.2 time triggered mode in time triggered mode, basic cycles can be sp lit into several time windows. a basic cycle starts with a reference message. each time a window is defined from the reference message, a transmit operation should occu r within a pre-defined time window. a mailbox must not win the arbitration in a previous time window, and it must not be retried if the arbitration is lost in the time window. teof (can_mr) mtimestamp (can_msrx) can_tim can bus mtimestamp (can_msry) message 1 message 2 start of frame timestamp (can_tstp) end of frame timestamp 1 timestamp 1 timestamp 2 timestamp 2
519 6042e?atarm?14-dec-06 at91sam7a3 preliminary figure 36-20. time triggered principle time trigger mode is enabled by setting the ttm field in the can_mr register. in time trig- gered mode, as in timestamp mode, the can_ timestp field captures the values of the internal counter, but the mtimestamp fields in the can_msrx registers are not active and are read at 0. synchronization by a reference message in time triggered mode, the internal timer counter is automatically reset when a new mes- sage is received in the last ma ilbox. this reset occurs after the reception of the end of frame on the rising edge of the mrdy signal in the ca n_msrx register. this allows synchronization of the internal timer counter with the reception of a reference message and the start a new time window. transmitting within a time window a time mark is defined for each mailbox. it is defined in the 16-bit mtimemark field of the can_mmrx register. at each internal timer cl ock cycle, the value of the can_tim is com- pared with each mailbox time mark. when the internal timer counter reaches the mtimemark value, an internal timer event for the mailbox is generated for the mailbox. in time triggered mode, transmit operations ar e delayed until the internal timer event for the mailbox. the application prepares a message to be sent by setting the mtcr in the can_mcrx register. the message is not sent until the can_tim value is less than the mtimemark value defined in the can_mmrx register. if the transmit operation is failed, i.e., the message loses the bus arbitration and the next trans- mit attempt is delayed until the nex t internal time trigger event. this prevents overlapping the next time window, but the message is still pendin g and is retried in the next time window when can_tim value equals the mtimemark value. it is also possible to prevent a retry by setting the drpt field in the can_mr register. freezing the internal timer counter the internal counter can be frozen by setting timfrz in the can_mr register. this prevents an unexpected roll-over when the counter reaches ffffh. when this occurs, it automatically freezes until a new reset is issued, either due to a message received in the last mailbox or any other reset counter operations. the tovf bit in the can_sr register is set when the counter is frozen. the tovf bit in the can_sr regist er is cleared by reading the can_sr register. depending on the corresponding interrupt mask in the can_imr register, an interrupt is gen- erated when tovf is set. reference message reference message global time time cycle time windows for messages
520 6042e?atarm?14-dec-06 at91sam7a3 preliminary figure 36-21. time triggered operations mrdy (can_msrlast_mailbox_number) can_tim can bus mrdy (can_msrx) end of frame timer event x mtimemarkx == can_tim timer event y mrdy (can_msry) mtimemarky == can_tim cleared by software internal counter reset message x arbitration lost message y arbitration win reference message message y mrdy (can_msrlast_mailbox_number) can_tim can bus mrdy (can_msrx) end of frame timer event x mtimemarkx == can_tim cleared by software internal counter reset message x arbitration win reference message message x basic cycle time window basic cycle time window
521 6042e?atarm?14-dec-06 at91sam7a3 preliminary 36.8 controller area networ k (can) user interface table 36-4. can memory map offset register name access reset state 0x0000 mode register can_mr read-write 0x0 0x0004 interrupt enable register can_ier write-only - 0x0008 interrupt disable register can_idr write-only - 0x000c interrupt mask register can_imr read-only 0x0 0x0010 status register can_sr read-only 0x0 0x0014 baudrate register can_br read/write 0x0 0x0018 timer register can_tim read-only 0x0 0x001c timestamp register can_timestp read-only 0x0 0x0020 error counter register can_ecr read-only 0x0 0x0024 transfer command register can_tcr write-only - 0x0028 abort command register can_acr write-only - 0x0100 - 0x01fc reserved ? ? ? 0x0200 mailbox 0 mode register can_mmr0 read/write 0x0 0x0204 mailbox 0 acceptance mask register can_mam0 read/write 0x0 0x0208 mailbox 0 id register can_mid0 read/write 0x0 0x020c mailbox 0 family id register can_mfid0 read-only 0x0 0x0210 mailbox 0 status register can_msr0 read-only 0x0 0x0214 mailbox 0 data low register can_mdl0 read/write 0x0 0x0218 mailbox 0 data high register can_mdh0 read/write 0x0 0x021c mailbox 0 control register can_mcr0 write-only - 0x0220 mailbox 1 mode register can_mmr1 read/write 0x0 0x0224 mailbox 1 acceptance mask register can_mam1 read/write 0x0 0x0228 mailbox 1 id register can_mid1 read/write 0x0 0x022c mailbox 1 family id register can_mfid1 read-only 0x0 0x0230 mailbox 1 status register can_msr1 read-only 0x0 0x0234 mailbox 1 data low register can_mdl1 read/write 0x0 0x0238 mailbox 1 data high register can_mdh1 read/write 0x0 0x023c mailbox 1 control register can_mcr1 write-only - ... ... ... ... -
522 6042e?atarm?14-dec-06 at91sam7a3 preliminary 36.8.1 can mode register name: can_mr access type: read/write canen: can controller enable 0 = the can controller is disabled. 1 = the can controller is enabled. lpm: disable/enable low power mode 0 = disable w power mode. 1 = enable low power mo can controller enters low power mode once all pending messages have been transmitted. abm: disable/enable autobaud/listen mode 0 = disable autobaud/listen mode. 1 = enable autobaud/listen mode. ovl: disable/enable overload frame 0 = no overload frame is generated. 1 = an overload frame is generated after each successful rec eption for mailboxes configured in receive with/without over- write mode, producer and consumer. teof: timestamp messages at each end of frame 0 = the value of can_tim is captured in the can_timestp register at each start of frame. 1 = the value of can_tim is captured in the can_timestp register at each end of frame. ttm: disable/enable time triggered mode 0 = time triggered mode is disabled. 1 = time triggered mode is enabled. timfrz: enable timer freeze 0 = the internal timer continues to be incremented after it reached 0xffff. 1 = the internal timer stops incrementing after reaching 0xffff. it is restarted after a timer reset. see ?freezing the inter- nal timer counter? on page 519 . drpt: disable repeat 0 = when a transmit mailbox loses the bus arbitration, the transfer request remains pending. 1 = when a transmit mailbox lose the bus arbitration, the transfe r request is automatically aborted. it automatically raises the mabt and mrdt flags in the corresponding can_msrx. 31 30 29 28 27 26 25 24 ????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 ???????? 76543210 drpt timfrz ttm teof ovl abm lpm canen
523 6042e?atarm?14-dec-06 at91sam7a3 preliminary 36.8.2 can interrupt enable register name: can_ier access type: write-only mbx: mailbox x interrupt enable 0 = no effect. 1 = enable mailbox x interrupt. erra: error active mode interrupt enable 0 = no effect. 1 = enable erra interrupt. warn: warning limit interrupt enable 0 = no effect. 1 = enable warn interrupt. errp: error passive mode interrupt enable 0 = no effect. 1 = enable errp interrupt. boff: bus-off mode interrupt enable 0 = no effect. 1 = enable boff interrupt. sleep: sleep interrupt enable 0 = no effect. 1 = enable sleep interrupt. wakeup: wakeup interrupt enable 0 = no effect. 1 = enable sleep interrupt. tovf: timer overflow interrupt enable 0 = no effect. 1 = enable tovf interrupt. tstp: timestamp interrupt enable 0 = no effect. 1 = enable tstp interrupt. cerr: crc error interrupt enable 0 = no effect. 1 = enable crc error interrupt. 31 30 29 28 27 26 25 24 ? ? ? berr ferr aerr serr cerr 23 22 21 20 19 18 17 16 tstp tovf wakeup sleep boff errp warn erra 15 14 13 12 11 10 9 8 mb15 mb14 mb13 mb12 mb11 mb10 mb9 mb8 76543210 mb7mb6mb5mb4mb3mb2mb1mb0
524 6042e?atarm?14-dec-06 at91sam7a3 preliminary serr: stuffing error interrupt enable 0 = no effect. 1 = enable stuffing error interrupt. aerr: acknowledgment error interrupt enable 0 = no effect. 1 = enable acknowledgment error interrupt. ferr: form error interrupt enable 0 = no effect. 1 = enable form error interrupt. berr: bit error interrupt enable 0 = no effect. 1 = enable bit error interrupt.
525 6042e?atarm?14-dec-06 at91sam7a3 preliminary 36.8.3 can interrupt disable register name: can_idr access type: write-only mbx: mailbox x interrupt disable 0 = no effect. 1 = disable mailbox x interrupt. erra: error active mode interrupt disable 0 = no effect. 1 = disable erra interrupt. warn: warning limit interrupt disable 0 = no effect. 1 = disable warn interrupt. errp: error passive mode interrupt disable 0 = no effect. 1 = disable errp interrupt. boff: bus-off mode interrupt disable 0 = no effect. 1 = disable boff interrupt. sleep: sleep interrupt disable 0 = no effect. 1 = disable sleep interrupt. wakeup: wakeup interrupt disable 0 = no effect. 1 = disable wakeup interrupt. tovf: timer overflow interrupt 0 = no effect. 1 = disable tovf interrupt. tstp: timestamp interrupt disable 0 = no effect. 1 = disable tstp interrupt. cerr: crc error interrupt disable 0 = no effect. 1 = disable crc error interrupt. 31 30 29 28 27 26 25 24 ? ? ? berr ferr aerr serr cerr 23 22 21 20 19 18 17 16 tstp tovf wakeup sleep boff errp warn erra 15 14 13 12 11 10 9 8 mb15 mb14 mb13 mb12 mb11 mb10 mb9 mb8 76543210 mb7mb6mb5mb4mb3mb2mb1mb0
526 6042e?atarm?14-dec-06 at91sam7a3 preliminary serr: stuffing error interrupt disable 0 = no effect. 1 = disable stuffing error interrupt. aerr: acknowledgment error interrupt disable 0 = no effect. 1 = disable acknowledgment error interrupt. ferr: form error interrupt disable 0 = no effect. 1 = disable form error interrupt. berr: bit error interrupt disable 0 = no effect. 1 = disable bit error interrupt.
527 6042e?atarm?14-dec-06 at91sam7a3 preliminary 36.8.4 can interrupt mask register name: can_imr access type: read-only mbx: mailbox x interrupt mask 0 = mailbox x interrupt is disabled. 1 = mailbox x interrupt is enabled. erra: error active mode interrupt mask 0 = erra interrupt is disabled. 1 = erra interrupt is enabled. warn: warning limit interrupt mask 0 = warning limit interrupt is disabled. 1 = warning limit interrupt is enabled. errp: error passive mode interrupt mask 0 = errp interrupt is disabled. 1 = errp interrupt is enabled. boff: bus-off mode interrupt mask 0 = boff interrupt is disabled. 1 = boff interrupt is enabled. sleep: sleep interrupt mask 0 = sleep interrupt is disabled. 1 = sleep interrupt is enabled. wakeup: wakeup interrupt mask 0 = wakeup interrupt is disabled. 1 = wakeup interrupt is enabled. tovf: timer overflow interrupt mask 0 = tovf interrupt is disabled. 1 = tovf interrupt is enabled. tstp: timestamp interrupt mask 0 = tstp interrupt is disabled. 1 = tstp interrupt is enabled. cerr: crc error interrupt mask 0 = crc error interrupt is disabled. 1 = crc error interrupt is enabled. 31 30 29 28 27 26 25 24 ? ? ? berr ferr aerr serr cerr 23 22 21 20 19 18 17 16 tstp tovf wakeup sleep boff errp warn erra 15 14 13 12 11 10 9 8 mb15 mb14 mb13 mb12 mb11 mb10 mb9 mb8 76543210 mb7mb6mb5mb4mb3mb2mb1mb0
528 6042e?atarm?14-dec-06 at91sam7a3 preliminary serr: stuffing error interrupt mask 0 = bit stuffing error interrupt is disabled. 1 = bit stuffing error interrupt is enabled. aerr: acknowledgment error interrupt mask 0 = acknowledgment error interrupt is disabled. 1 = acknowledgment error interrupt is enabled. ferr: form error interrupt mask 0 = form error interrupt is disabled. 1 = form error interrupt is enabled. berr: bit error interrupt mask 0 = bit error interrupt is disabled. 1 = bit error interrupt is enabled.
529 6042e?atarm?14-dec-06 at91sam7a3 preliminary 36.8.5 can status register name: can_sr access type: read-only mbx: mailbox x event 0 = no event occurred on mailbox x. 1 = an event occurred on mailbox x. an event corresponds to mrdy, mabt fields in the can_msrx register. erra: error active mode 0 = can controller is not in error active mode 1 = can controller is in error active mode this flag is set depending on tec and rec counter values. it is set when node is neither in error passive mode nor in bus off mode. this flag is automatically reset wh en above condition is not satisfied. warn: warning limit 0 = can controller warning limit is not reached. 1 = can controller warning limit is reached. this flag is set depending on tec and rec counters values. it is set when at least one of the counters values exceeds 96. this flag is automatically reset wh en above condition is not satisfied. errp: error passive mode 0 = can controller is not in error passive mode 1 = can controller is in error passive mode this flag is set depending on tec and rec counters values. a node is error passive when tec counter is greater or equal to 128 (decimal) or when the rec counter is greater or equal to 128 (decimal) and less than 256. this flag is automatically reset wh en above condition is not satisfied. boff: bus off mode 0 = can controller is not in bus-off mode 1 = can controller is in bus-off mode this flag is set depending on tec counter value. a node is bu s off when tec counter is greater or equal to 256 (decimal). this flag is automatically reset wh en above condition is not satisfied. 31 30 29 28 27 26 25 24 ovlsy tbsy rbsy berr ferr aerr serr cerr 23 22 21 20 19 18 17 16 tstp tovf wakeup sleep boff errp warn erra 15 14 13 12 11 10 9 8 mb15 mb14 mb13 mb12 mb11 mb10 mb9 mb8 76543210 mb7mb6mb5mb4mb3mb2mb1mb0
530 6042e?atarm?14-dec-06 at91sam7a3 preliminary sleep: can controller in low power mode 0 = can controller is not in low power mode. 1 = can controller is in low power mode. this flag is automatically reset when low power mode is disabled wakeup: can controller is not in low power mode 0 = can controller is in low power mode. 1 = can controller is not in low power mode. when a wakeup event occurs, the can cont roller is synchronized with the bus acti vity. messages can be transmitted or received. the can controller clock must be available when a w akeup event occurs. this flag is automatically reset when the can controller ente rs low power mode. tovf: timer overflow 0 = the timer has not rolled-over ffffh to 0000h. 1 = the timer rolls-over ffffh to 0000h. this flag is automatically clea red by reading can_sr register. tstp timestamp 0 = no bus activity has been detected. 1 = a start of frame or an end of frame has been detected (according to the teof field in the can_mr register). this flag is automatically cleare d by reading the can_sr register. cerr: mailbox crc error 0 = no crc error occurred duri ng a previous transfer. 1 = a crc error occurred during a previous transfer. a crc error has been detected during last reception. this flag is automatically clea red by reading can_sr register. serr: mailbox stuffing error 0 = no stuffing error occurred during a previous transfer. 1 = a stuffing error occurred during a previous transfer. a form error results from the detection of more than five consecutive bit with the same polarity. this flag is automatically clea red by reading can_sr register. aerr: acknowledgment error 0 = no acknowledgment error occurred during a previous transfer. 1 = an acknowledgment error occurred during a previous transfer. an acknowledgment error is detected when no detection of the dominant bit in the acknowledge slot occurs. this flag is automatically clea red by reading can_sr register. ferr: form error 0 = no form error occurred during a previous transfer 1 = a form error occurred during a previous transfer a form error results from violations on one or more of the fixed form of the following bit fields: ? crc delimiter ? ack delimiter ? end of frame ? error delimiter ? overload delimiter this flag is automatically clea red by reading can_sr register.
531 6042e?atarm?14-dec-06 at91sam7a3 preliminary berr: bit error 0 = no bit error occurred during a previous transfer. 1 = a bit error occurred during a previous transfer. a bit error is set when the bit value monitored on the line is different from the bit value sent. this flag is automatically clea red by reading can_sr register. rbsy: receiver busy 0 = can receiver is not receiving a frame. 1 = can receiver is receiving a frame. receiver busy. this status bit is set by hardware while can receiver is acquiring or monitoring a frame (remote, data, over- load or error frame). it is automati cally reset when can is not receiving. tbsy: transmitter busy 0 = can transmitter is not transmitting a frame. 1 = can transmitter is transmitting a frame. transmitter busy. this status bit is set by hardware while can transmitter is generating a frame (remote, data, overload or error frame). it is automatically reset when can is not transmitting. ovlsy: overload busy 0 = can transmitter is not transmitting an overload frame. 1 = can transmitter is transmitting a overload frame. it is automatically reset when the bus is not transmitting an overload frame.
532 6042e?atarm?14-dec-06 at91sam7a3 preliminary 36.8.6 can baudrate register name: can_br access type: read/write any modification on one of the fields of the canbr register must be done while can module is disabled. to compute the different bit timings, please refer to the section 36.6.4.1 ?can bit timing configuration? on page 500 . phase2: phase 2 segment this phase is used to compensate the edge phase error. warning : phase2 value must be different from 0. phase1: phase 1 segment this phase is used to compensate for edge phase error. propag: programming time segment this part of the bit time is used to compensa te for the physical delay times within the network. sjw: re-synchronization jump width to compensate for ph ase shifts between clock oscillators of different controllers on bus. the controller must re-synchronize on any relevant signal edge of the current transmission. the synchronization jump width defines the maximum of clock cycles a bit period may be shortened or lengthened by re-synchronization. brp: baudrate prescaler. this field allows user to program the period of the ca n system clock to determine the individual bit timing. the brp field must be within the range [1, 0x7f], i.e., brp = 0 is not authorized. smp: sampling mode 0 = the incoming bit stream is sampled once at sample point. 1 = the incoming bit stream is sampled three times with a period of a mck clock period, centered on sample point. smp sampling mode is automatically disabled if brp = 0. 31 30 29 28 27 26 25 24 ???????smp 23 22 21 20 19 18 17 16 ?brp 15 14 13 12 11 10 9 8 ? ? sjw ? propag 76543210 ? phase1 ? phase2 t phs2 t csc phase2 1 + () = t phs1 t csc phase1 1 + () = t prs t csc propag 1 + () = t sjw t csc sjw 1 + () = t csc brp 1 + () mck ? =
533 6042e?atarm?14-dec-06 at91sam7a3 preliminary 36.8.7 can timer register name: can_tim access type: read-only timerx: timer this field represents the internal can controller 16-bit timer value. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 timer15 timer14 timer13 timer12 timer11 timer10 timer9 timer8 76543210 timer7 timer6 timer5 timer4 timer3 timer2 timer1 timer0
534 6042e?atarm?14-dec-06 at91sam7a3 preliminary 36.8.8 can timestamp register name: can_timestp access type: read-only mtimestampx: timestamp this field represents the internal can controller 16-bit timer value. if the teof bit is cleared in the can_mr register, the inte rnal timer counter value is captured in the mtimestamp field at each start of frame. else the value is captured at each end of frame. when the value is captured, the tstp flag is set in the can_sr register. if the tstp mask in the can_imr register is set, an interrupt is generate d while tstp flag is set in the can_sr register. this flag is cl eared by reading the can_sr register. note: the can_timestp register is reset when the can is di sabled then enabled thanks to the canen bit in the can_mr. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 mtimestamp 15 mtimestamp 14 mtimestamp 13 mtimestamp 12 mtimestamp 11 mtimestamp 10 mtimestamp 9 mtimestamp 8 76543210 mtimestamp 7 mtimestamp 6 mtimestamp 5 mtimestamp 4 mtimestamp 3 mtimestamp 2 mtimestamp 1 mtimestamp 0
535 6042e?atarm?14-dec-06 at91sam7a3 preliminary 36.8.9 can error counter register name: can_ecr access type: read-only rec: receive error counter when a receiver detects an error, rec will be increased by one, except when the detected error is a bit error while sending an active error flag or an overload flag. when a receiver detects a dominant bit as the first bit after sending an error flag, rec is increased by 8. when a receiver detects a bit error while sending an active erro r flag, rec is increased by 8. any node tolerates up to 7 co nsecutive dominant bits af ter sending an active error flag, passive error flag or overload flag. after detecting the 14th consecutive domina nt bit (in case of an active error flag or an over- load flag) or after detecting the 8t h consecutive dominant bit following a passive error flag, and after each sequence of additional eight co nsecutive dominant bits, each receiver increases its rec by 8. after successful reception of a message, rec is decreased by 1 if it was between 1 and 127. if rec was 0, it stays 0, and if it was greater than 127, then it is set to a value between 119 and 127. tec: transmit error counter when a transmitter sends an error flag , tec is increased by 8 except when ? the transmitter is error passive and detects an acknowledgment error because of not detecting a dominant ack and does not dete ct a dominant bit while sending its passive error flag. ? the transmitter sends an error flag because a stuff error occurred during arbitration and should have been recessive and has been sent as recessive but monitored as dominant. when a transmitter detects a bit erro r while sending an active error flag or an overload flag, the tec will be increased by 8. any node tolerates up to 7 co nsecutive dominant bits af ter sending an active error flag, passive error flag or overload flag. after detecting the 14th consecutive domina nt bit (in case of an active error flag or an over- load flag) or after detecting the 8t h consecutive dominant bit following a passive error flag, and after each sequence of additional eight co nsecutive dominant bits every tran smitter increases its tec by 8. after a successful transmission the tec is decreased by 1 unless it was already 0. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 tec 15 14 13 12 11 10 9 8 ???????? 76543210 rec
536 6042e?atarm?14-dec-06 at91sam7a3 preliminary 36.8.10 can transfer command register name: can_tcr access type: write-only this register initializes several transfer requests at the same time. mbx: transfer request for mailbox x this flag clears the mrdy and mabt flags in the corresponding can_msrx register. when several mailboxes are requested to be transmitted simult aneously, they are transmitted in turn, starting with the mail- box with the highest priority. if several mailboxes have the same priority, then the mailbox with the lowest number is sent first (i.e., mb0 will be tr ansferred before mb1). timrst: timer reset resets the internal timer counter. if the internal timer count er is frozen, this command automatically re-enables it. this command is useful in time triggered mode. 31 30 29 28 27 26 25 24 timrst??????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 mb15 mb14 mb13 mb12 mb11 mb10 mb9 mb8 76543210 mb7mb6mb5mb4mb3mb2mb1mb0 mailbox object type description receive it receives the next message. receive with overwrite this triggers a new reception. transmit sends data prepared in the mailbox as soon as possible. consumer sends a remote frame. producer sends data prepared in the mailbox after receiving a remote frame from a consumer.
537 6042e?atarm?14-dec-06 at91sam7a3 preliminary 36.8.11 can abort command register name: can_acr access type: write-only this register initializes several abort requests at the same time. mbx: abort request for mailbox x it is possible to set macr field (in the can_mcrx register) for each mailbox. 31 30 29 28 27 26 25 24 ???????? 23 22 21 20 19 18 17 16 ???????? 15 14 13 12 11 10 9 8 mb15 mb14 mb13 mb12 mb11 mb10 mb9 mb8 76543210 mb7mb6mb5mb4mb3mb2mb1mb0 mailbox object type description receive no action receive with overwrite no action tr a n s m i t cancels transfer request if the me ssage has not been transmitted to the can transceiver. consumer cancels the current transfer before the remote frame has been sent. producer cancels the current transfer. the next remote frame is not serviced.
538 6042e?atarm?14-dec-06 at91sam7a3 preliminary 36.8.12 can message mode register name: can_mmrx access type: read/write mtimemark: mailbox timemark this field is active in time triggered mode. transmit operatio ns are allowed when the internal timer counter reaches the mailbox timemark. see ?transmitting within a time window? on page 519 . in timestamp mode, mtimemark is set to 0. prior: mailbox priority this field has no effect in receive and receive with overwrite modes. in these modes, the mailbox with the lowest number is serviced first. when several mailboxes try to transmit a message at the same time, the mailbox with the highest priority is serviced first. if several mailboxes have the same priority, the mailbox with the lowest num ber is serviced first (i.e., mbx0 is serviced before mbx 15 if they have the same priority). mot: mailbox object type this field allows the user to define the type of the mailbox. all mailboxes are independently configurable. five different types are possible for each mailbox: 31 30 29 28 27 26 25 24 ????? mot 23 22 21 20 19 18 17 16 ???? prior 15 14 13 12 11 10 9 8 mtimemark15 mtimemark14 mtimemark13 mtimemark12 mtimemark11 mtimemark10 mtimemark9 mtimemark8 76543210 mtimemark7 mtimemark6 mtimemark5 mtimemark4 mtimemark3 mtimemark2 mtimemark1 mtimemark0 mot mailbox object type 000 mailbox is disabled. this prevents receiving or transmitting any messages with this mailbox. 001 reception mailbox. mailbox is configured for reception. if a message is received while the mailbox data register is full, it is discarded. 010 reception mailbox with overwrite. mailbox is configured for reception. if a message is received while the mailbox is full, it overwrites the previous message. 0 1 1 transmit mailbox. mailbox is configured for transmission. 100 consumer mailbox. mailbox is configured in reception but behaves as a transmit mailbox, i.e., it sends a remote frame and waits for an answer. 101 producer mailbox. mailbox is configured in transmission but also behaves like a reception mailbox, i.e., it waits to receive a remote frame before sending its contents. 1 1 x reserved
539 6042e?atarm?14-dec-06 at91sam7a3 preliminary 36.8.13 can message acceptance mask register name: can_mamx access type: read/write to prevent concurrent access with the internal can core, the application must disable the mailbox before writing to can_mamx registers. midvb: complementary bits for identifier in extended frame mode acceptance mask for corresponding field of the message idvb register of the mailbox. midva: identifier for standard frame mode acceptance mask for corresponding field of the message idva register of the mailbox. mide: identifier version 0= compares idva from the received frame with th e can_midx register masked with can_mamx register. 1= compares idva and idvb from the received frame with the can_midx register masked with can_mamx register. 31 30 29 28 27 26 25 24 ? ? mide midva 23 22 21 20 19 18 17 16 midva midvb 15 14 13 12 11 10 9 8 midvb 76543210 midvb
540 6042e?atarm?14-dec-06 at91sam7a3 preliminary 36.8.14 can message id register name: can_midx access type: read/write to prevent concurrent access with the internal can core, the application must disable the mailbox before writing to can_midx registers. midvb: complementary bits for identifier in extended frame mode if mide is cleared, midvb value is 0. mide: identifier version this bit allows the user to define the version of messages pr ocessed by the mailbox. if set, mailbox is dealing with version 2.0 part b messages; otherwise, mailbox is dealing with version 2.0 part a messages. midva: identifier for standard frame mode 31 30 29 28 27 26 25 24 ? ? mide midva 23 22 21 20 19 18 17 16 midva midvb 15 14 13 12 11 10 9 8 midvb 76543210 midvb
541 6042e?atarm?14-dec-06 at91sam7a3 preliminary 36.8.15 can message family id register name: can_mfidx access type: read-only mfid: family id this field contains the concatenation of can_midx register bits masked by the can_mamx register. this field is useful to speed up message id decoding. the message acceptance procedure is described below. as an example: can_midx = 0x305a4321 can_mamx = 0x3ff0f0ff can_mfidx = 0x000000a3 31 30 29 28 27 26 25 24 ??? mfid 23 22 21 20 19 18 17 16 mfid 15 14 13 12 11 10 9 8 mfid 76543210 mfid
542 6042e?atarm?14-dec-06 at91sam7a3 preliminary 36.8.16 can message status register name: can_msrx access type: read only these register fields are updated each time a message transfer is received or aborted. mmi is cleared by reading the can_msrx register. mrdy, mabt are cleared by writing mtcr or macr in the can_mcrx register. warning: mrtr and mdlc state depends partly on the mailbox object type. mtimestamp: timer value this field is updated only when time-triggered operations are di sabled (ttm cleared in can_mr register). if the teof field in the can_mr register is cleared, timestamp is the internal timer value at the start of frame of the last message received or sent by the mailbox. if the teof field in the can_mr register is set, timestamp is the internal timer value at the end of frame of the last message received or sent by the mailbox. in time triggered mode, mtimestamp is set to 0. mdlc: mailbox data length code 31 30 29 28 27 26 25 24 ??????? mmi 23 22 21 20 19 18 17 16 mrdy mabt ? mrtr mdlc 15 14 13 12 11 10 9 8 mtimestamp 15 mtimestamp 14 mtimestamp 13 mtimestamp 12 mtimestamp 11 mtimestamp 10 mtimestamp 9 mtimestamp 8 76543210 mtimestamp 7 mtimestamp 6 mtimestamp 5 mtimestamp 4 mtimestamp 3 mtimestamp 2 mtimestamp 1 mtimestamp 0 mailbox object type description receive length of the first mailbox message received receive with overwrite length of the last mailbox message received transmit no action consumer length of the mailbox message received producer length of the mailbox message to be sent after the remote frame reception
543 6042e?atarm?14-dec-06 at91sam7a3 preliminary mrtr: mailbox remote transmission request mabt: mailbox message abort an interrupt is triggered when mabt is set. 0 = previous transfer is not aborted. 1 = previous transfer has been aborted. this flag is cleared by writing to can_mcrx register mailbox object type description receive the first frame received has the rtr bit set. receive with overwrite the last frame received has the rtr bit set. transmit reserved consumer reserved. after setting the mot fi eld in the can_mmr, mrtr is reset to 1. producer reserved. after setting the mot field in the can_mmr, mrtr is reset to 0. mailbox object type description receive reserved receive with overwrite reserved transmit previous transfer has been aborted consumer the remote frame transfer request has been aborted. producer the response to the remote frame transfer has been aborted.
544 6042e?atarm?14-dec-06 at91sam7a3 preliminary mrdy: mailbox ready an interrupt is triggered when mrdy is set. 0 = mailbox data registers can not be read/written by the software application. can_mdx are locked by the can_mdx. 1 = mailbox data registers can be read/written by the software application. this flag is cleared by writing to can_mcrx register. mmi: mailbox message ignored 0 = no message has been ignored during the previous transfer 1 = at least one message has been ignored during the previous transfer cleared by reading the can_msrx register. mailbox object type description receive at least one message has been received since the last mailbox transfer order. data from the first frame received can be read in the can_mdxx registers. after setting the mot field in the can_mmr, mrdy is reset to 0. receive with overwrite at least one frame has been received since the last mailbox transfer order. data from the last frame received can be read in the can_mdxx registers. after setting the mot field in the can_mmr, mrdy is reset to 0. transmit mailbox data have been transmitted. after setting the mot field in the can_mmr, mrdy is reset to 1. consumer at least one message has been received since the last ma ilbox transfer order. data from the first message received can be read in the can_mdxx registers. after setting the mot field in the can_mmr, mrdy is reset to 0. producer a remote frame has been received, mailbox data have been transmitted. after setting the mot field in the can_mmr, mrdy is reset to 1. mailbox object type description receive set when at least two messages intended for the mailbox have been sent. the first one is available in the mailbox data register. others have been ignored. a mailbox with a lower priority may have accepted the message. receive with overwrite set when at least two messages intended for the mailbox have been sent. the last one is available in the mailbox data register. previous ones have been lost. transmit reserved consumer a remote frame has been sent by the mailbox but several messages have been received. the first one is available in the mailbox data register. others have been ignored. another mailbox with a lower priority may have accepted the message. producer a remote frame has been received, but no data are available to be sent.
545 6042e?atarm?14-dec-06 at91sam7a3 preliminary 36.8.17 can message data low register name: can_mdlx access type: read/write mdl: message data low value when mrdy field is set in the can_msrx register, the lower 32 bits of a received message can be read or written by the software application. otherwise, the mdl value is locked by the can controller to send/receive a new message. in receive with overwrite, the can controller may modify mdl value while the software application reads mdh and mdl registers. to check that mdh and mdl do not belong to differ ent messages, the application has to check the mmi field in the can_msrx register. in this mode, the software application must re-read can_mdh and can_mdl, while the mmi bit in the can_msrx register is set. bytes are received/sent on the bus in the following order: 1. can_mdl[7:0] 2. can_mdl[15:8] 3. can_mdl[23:16] 4. can_mdl[31:24] 5. can_mdh[7:0] 6. can_mdh[15:8] 7. can_mdh[23:16] 8. can_mdh[31:24] 31 30 29 28 27 26 25 24 mdl 23 22 21 20 19 18 17 16 mdl 15 14 13 12 11 10 9 8 mdl 76543210 mdl
546 6042e?atarm?14-dec-06 at91sam7a3 preliminary 36.8.18 can message data high register name: can_mdhx access type: read/write mdh: message data high value when mrdy field is set in the can_msrx re gister, the upper 32 bits of a received message are read or written by the soft- ware application. otherwise, the mdh value is locked by the can controller to send/receive a new message. in receive with overwrite, the can cont roller may modify mdh value while the so ftware application reads mdh and mdl registers. to check that mdh and mdl do not belong to differ ent messages, the application has to check the mmi field in the can_msrx register. in this mode, the software application must re-read can_mdh and can_mdl, while the mmi bit in the can_msrx register is set. bytes are received/sent on the bus in the following order: 1. can_mdl[7:0] 2. can_mdl[15:8] 3. can_mdl[23:16] 4. can_mdl[31:24] 5. can_mdh[7:0] 6. can_mdh[15:8] 7. can_mdh[23:16] 8. can_mdh[31:24] 31 30 29 28 27 26 25 24 mdh 23 22 21 20 19 18 17 16 mdh 15 14 13 12 11 10 9 8 mdh 76543210 mdh
547 6042e?atarm?14-dec-06 at91sam7a3 preliminary 36.8.19 can message control register name: can_mcrx access type: write-only mdlc: mailbox data length code mrtr: mailbox remote transmission request consumer situations can be handled automatically by setting th e mailbox object type in consumer. this requires only one mailbox. it can also be handled using two mailboxes, one in reception, the other in transmission. the mrtr and the mtcr bits must be set in the same time. 31 30 29 28 27 26 25 24 ?????? ?? 23 22 21 20 19 18 17 16 mtcr macr ? mrtr mdlc 15 14 13 12 11 10 9 8 ? ? ? ? ? ?? ? 76543210 ? ? ? ? ?? ?? mailbox object type description receive no action. receive with overwrite no action. transmit length of the mailbox message. consumer no action. producer length of the mailbox message to be sent after the remote frame reception. mailbox object type description receive no action receive with overwrite no action transmit set the rtr bit in the sent frame consumer no action, the rtr bit in the sent frame is set automatically producer no action
548 6042e?atarm?14-dec-06 at91sam7a3 preliminary macr: abort request for mailbox x it is possible to set macr field for several mailboxes in the same time, setting several bits to the can_acr register. mtcr: mailbox transfer command this flag clears the mrdy and mabt flags in the can_msrx register. when several mailboxes are requested to be transmitted simult aneously, they are transmitted in turn. the mailbox with the highest priority is serviced first. if several mailboxes have the same priority, the mailbox with the lowest number is serviced first (i.e., mbx0 will be serv iced before mbx 15 if they have the same priority). it is possible to set mtcr for several mailboxes at the same time by writing to the can_tcr register. mailbox object type description receive no action receive with overwrite no action tr a n s m i t cancels transfer request if the me ssage has not been transmitted to the can transceiver. consumer cancels the current transfer before the remote frame has been sent. producer cancels the current transfer. the next remote frame will not be serviced. mailbox object type description receive allows the reception of the next message. receive with overwrite triggers a new reception. transmit sends data prepared in the mailbox as soon as possible. consumer sends a remote transmission frame. producer sends data prepared in the mailbox after receiving a remote frame from a consumer.
549 6042e?atarm?14-dec-06 at91sam7a3 preliminary 37. at91sam7a3 electrical characteristics 37.1 absolute maximum ratings 37.2 dc characteristics the following characteristics are applicable to the operating temperature range: t a = -40c to 85c, unless otherwise spec- ified and are certified for a junction temperature up to t j = 100c and for vdd3v3 between 3.0 and 3.6v. table 37-1. absolute maximum ratings* operating temperature (industrial)...... -40 c to +85 c *notice: stresses beyond those listed under ?absolute maxi- mum ratings? may cause permanent damage to the device. this is a stress rating only and func- tional operation of the device at these or other con- ditions beyond those indicated in the operational sections of this specification is not implied. expo- sure to absolute maximum rating conditions for extended periods may affect device reliability. storage temperature ......................... -60c to +150c voltage on input pins with respect to ground ........ .................-0.3v to +5.5v maximum operating voltage (vdd1v8 and vddpll) ..................................... 1.95v maximum operating voltage (vdd3v3, vddbu and vddana) ........................ 3.6v total dc output current on all i/o lines .......... 200 ma table 37-2. dc characteristics symbol parameter conditions min typ max units v vdd1v8 dc supply core 1.65 1.95 v v vddpll dc supply pll 1.65 1.95 v v vdd3v3 dc supply i/os and flash 3.0 3.6 v v vddbu dc supply backup i/o lines 3.0 3.6 v v vddana dc supply analog 3.0 3.6 v v il input low-level voltage -0.3 0.8 v v ih input high-level voltage 2.0 5.5 v v ol output low-level voltage i o = 2 ma 0.4 v v oh output high-level voltage i o = 2 ma v dd3v3 - 0.4 v i leak input leakage current pullup resistors disabled (typ: t a = 25c, max: t a = 85c) 20 200 na i pullup input pull-up current pa0-pa31 pb0-pb29 connected to ground 143 321 600 a i pulldown input pull-down current, (tst, jtagsel) pins connected to v vdd3v3 135 295 550 a c in input capacitance 100-pin lqfp package 14.1 pf
550 6042e?atarm?14-dec-06 at91sam7a3 preliminary i sc static current on v vdd3v3 = 3.3v, mck = 500 hz t a = 25c 175 650 a all inputs driven at 1(including tms, tdi, tck, nrst) flash in standby mode all peripherals off t a = 85c 750 3200 on v vddbu = 3.6v t a = 25c 8.2 30 a all inputs driven fwkup, wkup0, wkup1 = 0 t a = 85c 50 150 i o output current pa0-pa31,pb0-pb29, nrst 2 ma table 37-2. dc characteristics (continued) symbol parameter conditions min typ max units table 37-3. 1.8v voltage regulator characteristics symbol parameter conditions min typ max units v dd3v3 supply voltage 3.0 3.3 3.6 v v dd1v8 output voltage 1.65 1.8 1.95 v i vdd3v3 current consumption after startup, no load 70 120 a t start startup time c load = 2.2 f, after v dd3v3 > 3.0v 150 s i o maximum dc output current v dd3v3 = 3.3v 130 ma table 37-4. dc flash characteristics symbol parameter conditions min max units i sb standby current @ 25c onto vdd1v8 = 1.8v onto vdd3v3 = 3.3v 10 20 a i cc active current random read @ 35mhz onto vdd1v8 = 1.8v onto vdd3v3 = 3.3v 3.0 0.8 ma write onto vdd1v8 = 1.8v onto vdd3v3 = 3.3v 400 5.5 a ma
551 6042e?atarm?14-dec-06 at91sam7a3 preliminary 37.3 power consumption typical power consumption of plls , slow clock and main oscillator. power consumption of power supply in three different modes: active, ultra low-power and backup. power consumption by peripheral: calculated as the difference in current measurement after having enabled then disabled the corresponding clock. 37.3.1 power consumption versus modes the values in table 37-5 and table 37-6 on page 552 are measured values of the power con- sumption with operating conditions as follows: v dd3v3 = v ddbu = v ddana = 3.3v v dd1v8 = v ddpll = 1.8v (internal regulator output) t a = 25 c usb pads deactivated there is no consumption on the i/os of the device figure 37-1. measures schematics these figures represent the power consumpti on typically measured on the power supplies. 1.8v vdd3v3 voltage regulator vdd1v8 vddpll 3.3v vddana vddbu amp2 amp1
552 6042e?atarm?14-dec-06 at91sam7a3 preliminary note: v vdd3v3 = 3.3v, t a = 25c, mck = 48 mhz table 37-5. typical power consumption for different modes mode conditions consumption unit active flash is read. arm core clock is 60 mhz. analog-to-digital converter activated. all peripheral clocks activated. usb transceiver enabled onto amp2 70 ma ultra low power flash is in standby mode. arm core in idle mode. mck @ 500 hz analog-to-digital converter de-activated. all peripheral clocks de-activated. usb transceiver disabled. onto amp2 175 a backup device only v ddbu powered onto amp1 8.2 a table 37-6. typical power consumption by peripheral in active mode peripheral consumption unit pio controller 7.5 na/mhz usart 27 udp 27 pwm 34 can 145 twi 2 spi 16 mci 35 ssc 35 timer counter channels 2 arm7 and system peripherals 510
553 6042e?atarm?14-dec-06 at91sam7a3 preliminary 37.4 crystal oscillat or characteristics the following characteristics are applicabl e to the operating temperature range: t a = -40c to 85c and worst case of power supply, unless otherwise specified. 37.4.1 rc oscillator characteristics 37.4.2 main oscillator characteristics notes: 1. c s is the shunt capacitance. 2. r s = 100-200 ?; c shunt = 2.0 - 2.5 pf; c m = 2 ? 1.5 ff (typ, worst case) using 1 k ohm serial resistor on xout. 3. r s = 50-100 ?; c shunt = 2.0 - 2.5 pf; c m = 4 - 3 ff (typ, worst case). 4. r s = 25-50 ?; c shunt = 2.5 - 3.0 pf; c m = 7 -5 ff (typ, worst case). 5. r s = 20-50 ?; c shunt = 3.2 - 4.0 pf; c m = 10 - 8 ff (typ, worst case). table 37-7. rc oscillator characteristics symbol parameter conditions min typ max unit 1/(t cprc ) rc oscillator frequency v ddbu = 3v 22 32 42 khz duty cycle 45 50 55 % t st startup time v ddbu = 3v 75 s i osc current consumption after startup time 2.5 a table 37-8. main oscillator characteristics symbol parameter conditions min typ max unit 1/(t cpmain ) crystal oscillator frequency 3 16 20 mhz c l1 , c l2 internal load capacitance (c l1 = c l2 ) integrated load capacitance ((xin or xout)) 34 40 46 pf c l equivalent load capacitance integrated load capacitance (xin and xout in series) 17 20 23 pf duty cycle 30 50 70 % t st startup time v ddpll = 1.2 to 2v c s = 3 pf (1) 1/(t cpmain ) = 3 mhz c s = 7 pf (1) 1/(t cpmain ) = 16 mhz c s = 7 pf (1) 1/(t cpmain ) = 20 mhz 14.5 1.4 1 ms i ddst standby current consumption standby mode 1 a p on drive level @3 mhz @8 mhz @16 mhz @20 mhz 15 30 50 50 w i dd on current dissipation @3 mhz (2) @8 mhz (3) @16 mhz (4) @20 mhz (5) 150 150 300 400 250 250 450 550 a c lext maximum external capacitor on xin and xout 10 pf
554 6042e?atarm?14-dec-06 at91sam7a3 preliminary 37.4.3 crystal characteristics 37.4.4 xin clock characteristics note: 1. these characteristics apply only when the main oscillator is in bypass mode (i.e., when moscen = 0 and oscbypass = 1 in the ckgr_mor register, see the clock generator main oscillator register table 37-9. crystal characteristics symbol parameter conditions min typ max unit esr equivalent series resistor rs fundamental @3 mhz fundamental @8 mhz fundamental @16 mhz fundamental @20 mhz 200 100 80 50 ? c m motional capacitance 8ff c shunt shunt capacitance 7pf table 37-10. xin clock electrical characteristics symbol parameter conditions min max units 1/(t cpxin ) xin clock frequency (1) 50.0 mhz t cpxin xin clock period (1) 20.0 ns t chxin xin clock high half-period (1) 0.4 x t cpxin 0.6 x t cpxin t clxin xin clock low half-period (1) 0.4 x t cpxin 0.6 x t cpxin c in xin input capacitance (1) 46 pf r in xin pull-down resistor (1) 500 k ? v xin_il v xin input low-level voltage (1) -0.3 0.2 x v ddpll v v xin_ih v xin input high-level voltage (1) 0.8 x v ddpll 1.95 v i ddbp bypass current consumption (1) 15 w/mhz
555 6042e?atarm?14-dec-06 at91sam7a3 preliminary 37.4.4.1 xin clock characteristics note: 1. these characteristics apply only wh en the main oscillator is in bypass mode (i.e., when moscen = 0 and oscbypass = 1 in the ckgr_mor register. (refer to the ?pmc clock generator main clock frequency register?.) table 37-11. xin clock electrical characteristics symbol parameter conditions min max units 1/(t cpxin ) xin clock frequency (1) 50.0 mhz t cpxin xin clock period (1) 20.0 ns t chxin xin clock high half-period (1) 0.4 x t cpxin 0.6 x t cpxin t clxin xin clock low half-period (1) 0.4 x t cpxin 0.6 x t cpxin c in xin input capacitance (1) 25 pf r in xin pull-down resistor (1) 500 k ? v xin_il v xin input low-level voltage (1) -0.3 0.2 x v ddpll v v xin_ih v xin input high-level voltage (1) 0.8 x v ddpll 1.95 v
556 6042e?atarm?14-dec-06 at91sam7a3 preliminary 37.5 pll characteristics note: startup time depends on pll rc filter. a calculation tool is provided by atmel. table 37-12. phase lock loop characteristics symbol parameter conditions min typ max unit f out output frequency field out of ckgr_pll is 00 80 160 mhz field out of ckgr_pll is 10 150 200 mhz f in input frequency 1 32 mhz i pll current consumption active mode 4 ma standby mode 1 a
557 6042e?atarm?14-dec-06 at91sam7a3 preliminary 37.6 usb transceiver characteristics 37.6.1 electrical characteristics 37.6.2 switching characteristics table 37-13. electrical parameters symbol parameter conditions min typ max unit input levels v il low level 0.8 v v ih high level 2.0 v v di differential input sensitivity |(d+) - (d-)| 0.2 v v cm differential input common mode range 0.8 2.5 v c in transceiver capacitance capacitance to ground on each line 9.18 pf i hi-z state data line leakage 0v < v in < 3.3v -10 +10 a r ext recommended external usb series resistor in series with each usb pin with 5% 27 ? output levels v ol low level output measured with r l of 1.425 kohm tied to 3.6v 0.0 0.3 v v oh high level output measured with r l of 14.25 kohm tied to gnd 2.8 3.6 v v crs output signal crossover voltage measure conditions described in figure 37-2 1.3 2.0 v consumption i vdd3v3 current consumption transceiver enabled in input mode ddp=1 and ddm=0 105 200 a i vdd1v8 current consumption 80 150 a table 37-14. in full speed symbol parameter conditions min typ max unit t fr transition rise time c load = 50 pf 4 20 ns t fe transition fall time c load = 50 pf 4 20 ns t frfm rise/fall time matching 90 111.11 %
558 6042e?atarm?14-dec-06 at91sam7a3 preliminary figure 37-2. usb data signal rise and fall times 10% 10% 90% v crs t r t f differential data lines rise time fall time fosc = 6mhz/750khz r ext =27 ohms c load buffer (b) (a)
559 6042e?atarm?14-dec-06 at91sam7a3 preliminary 37.7 analog-to-digital co nverter characteristics notes: 1. corresponds to 13 clock cycles at 5 mhz: 3 clock cycles for track and hol d acquisition time a nd 10 clock cycles for conversion. 2. corresponds to 15 clock cycles at 8 mhz: 5 clock cycles for track and hold acquisition time and 10 clock cycles for conversion. the user can drive adc input with impedance up to: z out (shtim -470) x 10 in 8-bit resolution mode z out (shtim -589) x 7.69 in 10-bit resolution mode with shtim (sample and hold time register) expressed in ns and z out expressed in ohms. table 37-15. channel conversion time and adc clock parameter conditions min typ max units adc clock frequency 10-bit resolution mode 5 mhz adc clock frequency 8-bit resolution mode 8 mhz startup time return from idle mode 20 s track and hold acquisition time 600 ns conversion time adc clock = 5 mhz 2 s conversion time adc clock = 8 mhz 1.25 s throughput rate adc clock = 5 mhz 384 (1) ksps throughput rate adc clock = 8 mhz 533 (2) ksps table 37-16. external voltage reference input parameter conditions min typ max units advref input voltage range 2.6 v vdd3v3 v advref average current on 13 samples with adc clock = 5 mhz 200 250 a current consumption on vdd3v3 0.55 1 ma table 37-17. analog inputs parameter min typ max units input voltage range 0v advref input leakage current 1a input capacitance 12 14 pf table 37-18. transfer characteristics parameter min typ max units resolution 10 bit integral non-linearity 1 3 lsb differential non-linearity 0.5 2 lsb offset error 1 2 lsb gain error 0.5 2 lsb
560 6042e?atarm?14-dec-06 at91sam7a3 preliminary 37.8 ac characteristics 37.8.1 master clock characteristics 37.8.2 i/o characteristics criteria used to define the maximum frequency of the i/os: output duty cycle (30%-70%) minimum output swing: 100 mv to vdd3v3 - 100 mv addition of rising and falling time inferior to 75% of the period notes: 1. pin group 1 = pa0 to pa31 and pb0-pb13 2. pin group 2 = pb14 to pb29 table 37-19. master clock waveform parameters symbol parameter conditions min max units 1/(t cpmck ) master clock frequency 60 mhz table 37-20. i/o characteristics symbol parameter conditions min max units freqmax i01 pin group 1 (1) frequency load: 20 pf 16 mhz pulseminh i01 pin group 1 (1) high level pulse width load: 20 pf 32 ns pulseminl i01 pin group 1 (1) low level pulse width load: 20 pf 32 ns freqmax i02 pin group 2 (2) frequency load: 20 pf 18 mhz pulseminh i02 pin group 2 (2) high level pulse width load: 20 pf 27 ns pulseminl i02 pin group 2 (2) low level pulse width load: 20 pf 27 ns
561 6042e?atarm?14-dec-06 at91sam7a3 preliminary 37.8.3 spi characteristics figure 37-3. spi master mode with (cpol = ncpha = 0) or (cpol= ncpha = 1) figure 37-4. spi master mode with (cpol=0 and ncpha=1) or (cpol=1 and ncpha=0) figure 37-5. spi slave mode with (cpo =0 and nc ph =1) or (cpol=1 and ncpha=0) spck miso mosi spi 2 spi 0 spi 1 spck miso mosi spi 5 spi 3 spi 4 spck miso mosi spi 6 spi 7 spi 8
562 6042e?atarm?14-dec-06 at91sam7a3 preliminary figure 37-6. spi slave mode with (cpol = ncpha = 0) or (cpol = ncpha = 1) note: 1. maximum external capacitor = 20 pf. 2. t cpmck : master clock period in ns. note that in spi master mode the atsam7se512/256/32 does not sample the data (miso) on the opposite edge where data clocks out (mosi) but the same edge is used as shown in fig- ure 37-3 and figure 37-4 . spck miso mosi spi 9 spi 10 spi 11 table 37-21. spi timings symbol parameter conditions min max units spi 0 miso setup time before spck rises (master) (1) 28.5 + (t cpmck )/2 (2) ns spi 1 miso hold time after spck rises (master) (1) 0ns spi 2 spck rising to mosi delay (master) (1) 2ns spi 3 miso setup time before spck falls (master) (1) 26.5 + (t cpmck )/2 (2) ns spi 4 miso hold time after spck falls (master) (1) 0ns spi 5 spck falling to mosi delay (master) (1) 2ns spi 6 spck falling to miso delay (slave) (1) 28 ns spi 7 mosi setup time before spck rises (slave) (1) 2ns spi 8 mosi hold time after spck rises (slave) (1) 3ns spi 9 spck rising to miso delay (slave) (1) 28 ns spi 10 mosi setup time before spck falls (slave) (1) 3ns spi 11 mosi hold time after spck falls (slave) (1) 3ns
563 6042e?atarm?14-dec-06 at91sam7a3 preliminary 37.8.4 embedded flash characteristics the maximum operating frequency is given in table 37-22 but is limited by the embedded flash access time when the pro- cessor is fetching code out of it. table 37-22 gives the device maximum operating frequency depending on the field fws of the mc_fmr register. this field defines the number of wait states required to access the embedded flash memory. table 37-22. embedded flash wait states fws read operations maximum operating frequency (mhz) 0 1 cycle 30 1 2 cycles 60 2 3 cycles 60 3 4 cycles 60 table 37-23. ac flash characteristics parameter condition min max units program cycle time per page including auto-erase 6 ms per page including auto-erase 3 ms full chip erase 15 ms
564 6042e?atarm?14-dec-06 at91sam7a3 preliminary 37.8.5 jtag/ice interface timings and signals 37.8.5.1 ice interface timings and signals note: 1. v vdd3v3 from 3.0v to 3.6v, maximum external capacitor = 40pf figure 37-7. ice interface signals table 37-24. ice interface timing specification symbol parameter conditions min max units ice 0 tck low half-period (1) 51 ns ice 1 tck high half-period (1) 51 ns ice 2 tck period (1) 102 ns ice 3 tdi, tms, setup before tck high (1) 0ns ice 4 tdi, tms, hold after tck high (1) 3ns ice 5 tdo hold time (1) 13 ns ice 6 tck low to tdo valid (1) 20 ns tck ice 3 ice 4 ice 6 tms/tdi tdo ice 5 ice 1 ice 2 ice 0
565 6042e?atarm?14-dec-06 at91sam7a3 preliminary 37.8.5.2 jtag interface timings and signals note: 1. v vdd3v3 from 3.0v to 3.6v, maximum external capacitor = 40pf figure 37-8. jtag interface signals table 37-25. jtag interface timing specification symbol parameter conditions min max units jtag 0 tck low half-period (1) 6.5 ns jtag 1 tck high half-period (1) 5.5 ns jtag 2 tck period (1) 12 ns jtag 3 tdi, tms setup before tck high (1) 2ns jtag 4 tdi, tms hold after tck high (1) 3ns jtag 5 tdo hold time (1) 4ns jtag 6 tck low to tdo valid (1) 16 ns jtag 7 device inputs setup time (1) 0ns jtag 8 device inputs hold time (1) 3ns jtag 9 device outputs hold time (1) 6ns jtag 10 tck to device outputs valid (1) 18 ns tck jtag 9 tms/tdi tdo device outputs jtag 5 jtag 4 jtag 3 jtag 0 jtag 1 jtag 2 jtag 10 device inputs jtag 8 jtag 7 jtag 6
566 6042e?atarm?14-dec-06 at91sam7a3 preliminary 38. at91sam7a3 mechanical characteristics 38.1 thermal considerations 38.1.1 thermal data table 38-1 summarizes the thermal resistance data depending on the package. 38.1.2 junction temperature the average chip-junction temperature, t j , in c can be obtained from the following: 1. 2. where: ja = package thermal resistance, junction-to-ambient (c/w), provided in table 38-1 on page 566 . jc = package thermal resistance, junction-to-case thermal resistance (c/w), provided in table 38-1 on page 566 . heat sink = cooling device thermal resistance (c/w), provided in the device datasheet. p d = device power consumption (w) estimated from data provided in the section ?power consumption? on page 551 . t a = ambient temperature (c). table 38-1. thermal resistance data symbol parameter condition package typ unit ja junction-to-ambient thermal resistance still air lqfp100 38.3 c/w jc junction-to-case thermal resistance lqfp100 8.7 t j t a p d ja () + = t j t a p ( d ( heatsink jc )) ++ =
567 6042e?atarm?14-dec-06 at91sam7a3 preliminary 38.2 package drawing figure 38-1. 100-lead lqfp package drawing
568 6042e?atarm?14-dec-06 at91sam7a3 preliminary table 38-2. 100-lead lqfp package dimensions symbol millimeter inch min nom max min nom max a1.600.63 a1 0.05 0.15 0.002 0.006 a2 1.35 1.40 1.45 0.053 0.055 0.057 d 16.00 bsc 0.630 bsc d1 14.00 bsc 0.551 bsc e 16.00 bsc 0.630 bsc e1 14.00 bsc 0.551 bsc r2 0.08 0.20 0.003 0.008 r1 0.08 0.003 q0 3.5 7 0 3.5 7 10 0 211 12 13 11 12 13 311 12 13 11 12 13 c 0.09 0.20 0.004 0.008 l 0.45 0.60 0.75 0.018 0.024 0.030 l1 1.00 ref 0.039 ref s 0.20 0.008 b 0.17 0.20 0.27 0.007 0.008 0.011 e 0.50 bsc 0.020 bsc d2 12.00 0.472 e2 12.00 0.472 tolerances of form and position aaa 0.20 0.008 bbb 0.20 0.008 ccc 0.08 0.003 ddd 0.08 0.003 table 38-3. device and 100-lead lqfp package maximum weight 800 mg table 38-4. 100-lead lqfp package characteristics moisture sensitivity level 3
569 6042e?atarm?14-dec-06 at91sam7a3 preliminary 38.3 soldering profile table 38-5 gives the recommended soldering profile from j-std-020c. note: the package is certified to be backward compatible with pb/sn soldering profile. a maximum of three reflow passes is allowed per component. table 38-5. soldering profile profile feature green package average ramp-up rate (217c to peak) 3 c/sec. max. preheat temperature 175c 25c 180 sec. max. temperature maintained above 217c 60 sec. to 150 sec. time within 5 c of actual peak temperature 20 sec. to 40 sec. peak temperature range 260 c ramp-down rate 6 c/sec. max. time 25 c to peak temperature 8 min. max.
570 6042e?atarm?14-dec-06 at91sam7a3 preliminary 39. at91sam7a3 ordering information table 39-1. ordering information ordering code package package type temperature operating range at91sam7a3-au lqfp 100 green industrial (-40 c to 85 c)
571 6042e?atarm?14-dec-06 at91sam7a3 preliminary 40. errata 40.1 marking all devices are marked with the atmel logo and the ordering code. additional marking has the following format: where ?yy?: manufactory year ?ww?: manufactory week ?v?: revision ?xxxxxxxxx?: lot number yyww v xxxxxxxxx arm
572 6042e?atarm?14-dec-06 at91sam7a3 preliminary 40.2 at91sam7a3 errata - rev. a parts refer to section 40.1 ?marking?, on page 571 40.2.1 multimedia card interface (mci) 40.2.1.1 mci: data timeout error flag as the data timeout error flag cannot rise, the mc i can be stalled waiting indefinitely the data start bit. problem fix/workaround a software timeout must be implemented and a stop command must be sent when the time- out has elapsed. 40.2.1.2 mci: stream command not supported the stream read/write commands are not supported by the mci. problem fix/workaround none. 40.2.1.3 mci: data fifo and status bits do not read/write the data fifo if rxrdy/txrdy status bits are not set. problem fix/workaround none. 40.2.1.4 mci: data fifo problem with pdc the shared fifo is reset at the beginning of a transfer command. problem fix/workaround in order not to lose data, it is mandatory to enable the pdc channel after having written to the command register. in order to achieve this sequenc e correctly it is mandatory to disable all it sources. 40.2.2 parallel input/output controller (pio) 40.2.2.1 pio: leakage on pb14 - pb29 when pb14 - pb29, (the i/o lines multiplexed with the analog inputs) are set as digital inputs with pull-up disabled, the leakage can be 25 a in worst case and 90 na in typical case per i/o when the i/o is set externally at low level. problem fix/workaround set the i/o to vddio by internal or external pull-up.
573 6042e?atarm?14-dec-06 at91sam7a3 preliminary 40.2.2.2 pio: electrical characteristics pa0-pa31 and pb0-pb13 when pa0-pa31 or pb0-pb13 are set as digital inputs with pull-up enabled, the voltage of the i/o stabilizes at vpull-up. this condition causes a leakage through vddio. th is leakage is 45 a per pad in worst case at 3.3 v. problem fix/workaround it is recommended to use an external pull-up if needed. 40.2.2.3 pio: drive low pa0-pa31 and pb0-pb13 when nrst or pa0-pa31 and or pb0-pb13 are set as digital inputs with pull-up enabled, driv- ing the i/o with an output impedance higher than 500 ohms may not drive the i/o to a logical zero. problem fix/workaround output impedance must be lower than 500 ohms. 40.2.3 power management controller (pmc) 40.2.3.1 pmc: main oscillator measur e in bypass mode it is not possible to measure the main oscillato r in bypass mode (number of main clock cycles during 16 periods of slow clock set in ckgr_m cfr). measurement is possible with an external crystal. problem fix/workaround none. 40.2.4 pulse width modulation (pwm) controller 40.2.4.1 pwm: constraints on duty cycle value a value of 0 is forbidden in the chan nel duty cycle register (pwm_cdtyx). problem fix/workaround 0 corresponds to a permanent high or low signal. the pio controller may ensure this level when needed by disabling pwm, and using the corresponding i/o as an output with a value 0 or 1. 40.2.4.2 pwm: update when pwm_ccntx = 0 or 1 if the channel counter register value is 0 or 1, the channel period register or channel duty cycle register is directly modified when writing the channel update register. vpull-up vpull-up min vpull-up max vddio - 0.65 v vddio - 0.45 v i leakage parameter typ max i leakage at 3.3v 2.5 a 45 a
574 6042e?atarm?14-dec-06 at91sam7a3 preliminary problem fix/workaround check the channel counter register before writing the update register. 40.2.4.3 pwm: update when pwm_cprdx = 0 when channel period register equals 0, the period update is not operational. problem fix/workaround do not write 0 in the period register. 40.2.4.4 pwm: counter start value in left-aligned mode, the first start value of the counter is 0. for the other periods, the counter starts at 1. problem fix/workaround none. 40.2.4.5 pwm: behavior of chidx status bits in the pwm_sr register erratic behavior of the chidx status bit in the pwm_sr register. when a channel is disabled by writing in the pwm_dis register just after enabling it (before completion of a clock period of the clock selected for the channel), the pwm line is internally disabled but the chidx status bit in the pwm_sr stays at 1. problem fix/workaround do not disable a channel before completion of one period of the selected clock. 40.2.5 real time timer: rtt 40.2.5.1 rtt: possible event loss when reading rtt_sr if an event (rttinc or alms) occurs within the same slow clock cycle during which the rtt_sr is read, the corresponding bit might be clea red. this can lead to the loss of this event. problem fix/workaround: the software must handle the rtt event as an interrupt and should not poll rtt_sr. 40.2.6 serial peripheral interface (spi) 40.2.6.1 spi: pulse generation on spck in master mode, there is an additional pulse generated on spck when the spi is configured as follows: ? the baudrate is odd and different from 1 ? the polarity is set to 1 ? the phase is set to 0 problem fix/workaround none.
575 6042e?atarm?14-dec-06 at91sam7a3 preliminary 40.2.6.2 spi: bad tx_ready behavior when csaat = 1 and scbr = 1 if the spi2 is programmed with csaat = 1, sc br(baudrate) = 1 and two transfers are per- formed consecutively on the same slave with an idle state between them, the tx_ready signal does not rise after the second data has been transferred in the shifter. this can imply for exam- ple, that the second data is sent twice. problem fix/workaround do not use the combination csaat = 1 and scbr = 1. 40.2.6.3 spi: lastxfer (last transfer) behavior in fixed mode, with csaat bit set, and in ?pdc mode? the chip select can rise depending on the data written in the spi_tdr when the tx_empty flag is set. if for example, the pdc writes a ?1? in the bit 24 (lastxfer bit) of the spi_td r, the chip select will rise as soon as the txempty flag is set. problem fix/workaround use the cs in pio mode when pdc mode is requ ired and cs has to be maintained between transfers. 40.2.6.4 spi: spck behavior in master mode spck pin can toggle out before the first transfer in master mode. problem fix/workaround in master mode, mstr bit must be set (in spi_mr register) before configuring spi_csrx registers. 40.2.6.5 spi: chip select and fixed mode in fixed mode, if a transfer is performed through a pdc on a chip select different from the chip select 0, the output spi_size sampled by the pdc will depend on t he field, bits (bits per trans- fer) of spi_csr0 register, whatever the selected chip select is. for example, if spi_csr0 is configured for a 10-bit transfer whereas spi_csr1 is configured for an 8-bit transfer, when a transfer is performed in fixed mo de through the pdc, on chip sele ct 1, the transfer will be con- sidered as a halfword transfer. problem fix/workaround if a pdc transfer has to be performed in 8 bits, on a chip select y (y as different from 0), the bits field of the spi_csr0 must be configured in 8 bits, in the same way as the bits field of the csry register. 40.2.6.6 spi: baudrate set to 1 when baudrate is set at 1 (i.e. when serial clock frequency equals the system clock frequency) and when the bits field of the spi_csr register (number of bits to be transmitted) equals an odd value (in this case 9,11,13 or 15), an additional pulse will be gene rated on output spck. everything is ok if the bits field equals 8,10,12,14 or 16 and baudrate = 1. problem fix/workaround none.
576 6042e?atarm?14-dec-06 at91sam7a3 preliminary 40.2.6.7 spi: disable issue the spi command ?spi disable? is not possibl e during a transfer, it must be performed only after tx_empty rising else there is everlasting dummy transfers occur. problem fix/workaround none. 40.2.6.8 spi: disable in slave mode the spi disable is not possible in slave mode. problem fix/workaround read first the received data, then perform the software reset. 40.2.6.9 spi: software reset and spien bit the spi command ?software reset? does not reset the spien config bit. therefore rewriting an spi enable command does not set tx_ready, tx_empty flags. problem fix/workaround send spi disable command after a software reset. 40.2.6.10 spi: csaat = 1 and delay if csaat = 1 for current access and there is no more tx request for a time greater than dlybct + dlybcs, then if an access is requested on another slave, the npcs bus switches from one cs to the one requested wit hout dlybcs. external slaves may reach a con- tention on spi_miso line for a short period. problem fix/workaround assert the last transfer command (npcs de-activation) for the last character of each slave. 40.2.7 synchronous serial controller (ssc) 40.2.7.1 ssc: periodic transmission limitations in master mode if the least significant bit is sent first (msbf = 0), the first tag during the frame synchro is not sent. problem fix/workaround none. 40.2.7.2 ssc: transmitter limitations in slave mode if tk is programmed as output and tf is programmed as input, it is impossible to emit data when the start of edge (risin g or falling) of synchro has a start delay equal to zero. problem fix/workaround none. 40.2.7.3 ssc: transmitter limitations in slave mode if tk is programmed as an input and tf is programmed as an output and requested to be set to low/high during data emission, the frame synchro signal is generated one bit clock period after
577 6042e?atarm?14-dec-06 at91sam7a3 preliminary the data start and one data bit is lost. this pr oblem does not exist when generating a periodic synchro. problem fix/workaround the data need to be delayed for one bit clock period with an external assembly. in the following schematic, td, tk and nrst are at91sam7a3 signals, txd is the delayed data to connect to the device. 40.2.8 two-wire interface (twi) 40.2.8.1 twi: clock divider the value of cldiv x 2 ckdiv must be less than or equal to 8191 , the value of chdiv x 2 ckdiv must be less than or equal to 8191 ? problem fix/workaround none. 40.2.8.2 twi: possible receiv e holding register corruption when loading the twi_rhr, the transfer direction is ignored. the last data byte received in the twi_rhr is corrupted at the end of the first subsequent transmit data byte. neither rxrdy nor overrun status bits ar e set if this occurs. problem fix/workaround the user must be sure that received data is read before transmitting any new data. 40.2.8.3 twi: nack status bit lost during a master frame, if twi_sr is read between the non acknowledge condition detection and the txcomp bit rising in the twi_sr, the nack bit is not set. problem fix/workaround
578 6042e?atarm?14-dec-06 at91sam7a3 preliminary the user must wait for the txcomp status bit by interrupt and must not read the twi_sr as long as transmission is not completed. note: txcomp and nack fields are set simultaneously a nd the nack field is reset after the read of the twi_sr. 40.2.8.4 twi: disabling does not operate correctly any transfer in progress is immediately frozen if the control register (twi_cr) is written with the bit msdis at 1. furthermore, the status bits txcomp and txrdy in the status register (twi_sr) are not reset. problem fix/workaround the user must wait for the end of transfer before disabling the twi. in addition, the interrupts must be disabled before disabling the twi. 40.2.8.5 twi: software reset when a software reset is performed during a frame and when twck is low, it is impossible to ini- tiate a new transfer in read or write mode. problem fix/workaround none. 40.2.9 universal synchronous asynchronous receiver transmitter (usart) 40.2.9.1 usart: hardware handshaking ? two characters sent if cts switches from 0 to 1 during the tx of a character and if the holding register (us_thr) is not empty, the content of us _thr will also be transmitted. problem fix/workaround don't use the pdc in transmit mode and do no t fill us_thr before txempty is set at 1. 40.2.9.2 usart: xoff character bad behavior the xoff character is sent only when the receive buffer is detected full. while the xoff is being sent, the remote transmitter is still transmitting. as only one holding re gister is available in the receiver, characters will be lo st in reception. th is makes the software handshaking function- ality ineffective. problem fix/workaround none. 40.2.10 vddbu 40.2.10.1 vddbu: idd when accessing the apb during access to apb (via any peripheral) th e current consumption on vddbu increases. it typically adds 20 a. problem fix/workaround minimize the apb access if the current cons umption over vddbu is a key point in the application.
579 6042e?atarm?14-dec-06 at91sam7a3 preliminary 40.2.10.2 vddbu: idd when vddcore falls when vddcore rises or falls , there is a dynamic powe r consumption over vddbu. this transient consumption is typically 400 a during 10 ms. problem fix/workaround minimize the number of power-on and power-of f on vddcore if the current consumption over vddbu is a key point in the application.
580 6042e?atarm?14-dec-06 at91sam7a3 preliminary
i 6042e?atarm?14-dec-06 at91sam7a3 preliminary table of contents features ................ ................ .............. ............... .............. .............. ............ 1 1 description ............ .............. .............. ............... .............. .............. ............ 3 2 block diagram ............ ................ ................. ................ ................. ............ 4 3 signal description ............. .............. ............... .............. .............. ............ 5 4 package ............... ................ .............. ............... .............. .............. ............ 8 4.1 100-lead lqfp package outline ...........................................................................8 4.2 pinout ................................................................................................................. ...9 5 power considerations ........ .............. ............... .............. .............. .......... 10 5.1 power supplies ...................................................................................................10 5.2 voltage regulator ................................................................................................10 5.3 typical powering schematics .............................................................................11 6 i/o lines considerations ....... .............. .............. .............. .............. ........ 12 6.1 jtag port pins ....................................................................................................12 6.2 test pin ............................................................................................................... 12 6.3 reset pin .............................................................................................................1 2 6.4 pio controller a and b lines ..............................................................................12 6.5 shutdown logic pins ...........................................................................................12 6.6 i/o line drive levels ...........................................................................................12 7 processor and architecture .... ................ ................. ................ ............. 13 7.1 arm7tdmi processor ........................................................................................13 7.2 debug and test features ....................................................................................13 7.3 memory controller ...............................................................................................13 7.4 peripheral dma controller ..................................................................................14 8 memory .............. ................ ................ ............... .............. .............. .......... 15 8.1 embedded memories ..........................................................................................15 8.2 memory mapping .................................................................................................17 8.3 embedded flash .................................................................................................17 9 system controller ............. ................ ............... .............. .............. .......... 19 9.1 system controller mapping .................................................................................20
ii 6042e?atarm?14-dec-06 at91sam7a3 preliminary 9.2 reset controller ..................................................................................................21 9.3 clock generator ..................................................................................................21 9.4 power management controller ............................................................................21 9.5 advanced interrupt controller .............................................................................22 9.6 debug unit ..........................................................................................................23 9.7 period interval timer ...........................................................................................23 9.8 watchdog timer ..................................................................................................23 9.9 real-time timer ...................................................................................................23 9.10 shutdown controller ..........................................................................................23 9.11 pio controllers a and b ....................................................................................23 10 peripherals ............ .............. .............. ............... .............. .............. .......... 25 10.1 peripheral mapping ...........................................................................................25 10.2 peripheral multiplexing on pio lines ................................................................26 10.3 pio controller a multiplexing ............................................................................27 10.4 pio controller b multiplexing ............................................................................28 11 peripheral identifiers ........ ................ ............... .............. .............. .......... 29 11.1 serial peripheral interface .................................................................................30 11.2 two-wire interface .............................................................................................30 11.3 usart ..............................................................................................................30 11.4 serial synchronous controller ...........................................................................31 11.5 timer counter ...................................................................................................31 11.6 pwm controller .................................................................................................31 11.7 usb device port ...............................................................................................32 11.8 multimedia card interface .................................................................................32 11.9 can controller ..................................................................................................32 11.10 analog-to-digital converter .............................................................................33 12 arm7tdmi processor ............. ................ ................. ................ ............. 35 12.1 overview ...........................................................................................................35 12.2 arm7tdmi processor ......................................................................................35 13 at91sam7a3 debug and test features ........ .............. .............. .......... 41 13.1 overview ...........................................................................................................41 13.2 block diagram ...................................................................................................41 13.3 application examples ........................................................................................42 13.4 test environment ..............................................................................................43 13.5 debug and test pin description ........................................................................43
iii 6042e?atarm?14-dec-06 at91sam7a3 preliminary 13.6 functional description .......................................................................................44 14 reset controller (rstc) .... ............... ............... .............. .............. .......... 53 14.1 overview ...........................................................................................................53 14.2 block diagram ...................................................................................................53 14.3 functional description .......................................................................................53 14.4 reset controller (rstc) user interface ............................................................61 15 real-time timer (rtt) ......... .............. ............... .............. .............. .......... 65 15.1 overview ...........................................................................................................65 15.2 block diagram ...................................................................................................65 15.3 functional description .......................................................................................65 15.4 real-time timer (rtt) user interface ...............................................................67 16 periodic interval timer (pit) ................. .............. .............. ............ ........ 71 16.1 overview ...........................................................................................................71 16.2 block diagram ...................................................................................................71 16.3 functional description .......................................................................................71 16.4 periodic interval timer (pit) user interface ......................................................73 17 watchdog timer (wdt) ........... ................ ................. ................ ............. 77 17.1 overview ...........................................................................................................77 17.2 block diagram ...................................................................................................77 17.3 functional description .......................................................................................78 17.4 watchdog timer (wdt) user interface .............................................................80 18 shutdown controller (shdwc ) .............. ................. ................ ............. 83 18.1 overview ...........................................................................................................83 18.2 block diagram ...................................................................................................83 18.3 i/o lines description .........................................................................................84 18.4 product dependencies ......................................................................................84 18.5 functional description .......................................................................................84 18.6 shutdown controller (shdwc) user interface .................................................86 19 memory controller (mc) .... ............... ............... .............. .............. .......... 89 19.1 overview ...........................................................................................................89 19.2 block diagram ...................................................................................................89 19.3 functional description .......................................................................................90 19.4 memory controller (mc) user interface ............................................................94 20 embedded flash controller (efc) ............... .............. .............. ........... 101
iv 6042e?atarm?14-dec-06 at91sam7a3 preliminary 20.1 overview ..........................................................................................................101 20.2 functional description .....................................................................................101 20.3 embedded flash controller (efc) user interface ...........................................109 21 peripheral dma controller (pdc) ................ .............. .............. ........... 115 21.1 overview .........................................................................................................115 21.2 block diagram .................................................................................................115 21.3 functional description .....................................................................................116 21.4 peripheral dma controller (pdc) user interface ...........................................118 22 advanced interrupt controller (aic) ........... .............. .............. ........... 125 22.1 overview .........................................................................................................125 22.2 block diagram .................................................................................................125 22.3 application block diagram ..............................................................................126 22.4 aic detailed block diagram ............................................................................126 22.5 i/o line description .........................................................................................126 22.6 product dependencies ....................................................................................127 22.7 functional description .....................................................................................128 22.8 advanced interrupt controller (aic) user interface .........................................140 23 clock generator ................ .............. .............. .............. .............. ........... 151 23.1 description ......................................................................................................151 23.2 slow clock rc oscillator .................................................................................151 23.3 main oscillator .................................................................................................151 23.4 divider and pll block .....................................................................................153 24 power management controller (pmc) .... ................. ................ ........... 155 24.1 description ......................................................................................................155 24.2 master clock controller ...................................................................................155 24.3 processor clock controller ..............................................................................156 24.4 usb clock controller ......................................................................................156 24.5 peripheral clock controller .............................................................................156 24.6 programmable clock output controller ...........................................................157 24.7 programming sequence ..................................................................................157 24.8 clock switching details ...................................................................................161 24.9 power management controller (pmc) user interface ....................................164 25 debug unit (dbgu ..... ................ ................. ................ .............. ........... 181 25.1 overview .........................................................................................................181
v 6042e?atarm?14-dec-06 at91sam7a3 preliminary 25.2 block diagram .................................................................................................182 25.3 product dependencies ....................................................................................183 25.4 uart operations ............................................................................................183 25.5 debug unit user interface ..............................................................................190 26 parallel input output contro ller (pio) ......... .............. .............. ........... 205 26.1 overview .........................................................................................................205 26.2 block diagram .................................................................................................206 26.3 product dependencies ....................................................................................207 26.4 functional description .....................................................................................208 26.5 i/o lines programming example ....................................................................213 26.6 user interface ..................................................................................................214 27 serial peripheral interface (spi) ................ ................ .............. ........... 231 27.1 overview .........................................................................................................231 27.2 block diagram .................................................................................................232 27.3 application block diagram ..............................................................................233 27.4 signal description ..........................................................................................234 27.5 product dependencies ....................................................................................234 27.6 functional description .....................................................................................235 27.7 serial peripheral interface (spi) user interface ..............................................244 28 two-wire interface (twi) .... .............. ............... .............. .............. ........ 257 28.1 overview .........................................................................................................257 28.2 block diagram .................................................................................................257 28.3 application block diagram ..............................................................................257 28.4 product dependencies ....................................................................................258 28.5 functional description .....................................................................................259 28.6 two-wire interface (twi) user interface ........................................................264 29 universal synchronous a synchronous receiver transceiver (usart) ................. ................. ................ ................. ................ ............. 273 29.1 block diagram .................................................................................................274 29.2 application block diagram ..............................................................................275 29.3 i/o lines description ......................................................................................275 29.4 product dependencies ....................................................................................276 29.5 functional description .....................................................................................277 29.6 usart user interface ....................................................................................300 30 synchronous serial controller (ssc) .... ................. ................ ........... 317
vi 6042e?atarm?14-dec-06 at91sam7a3 preliminary 30.1 overview .........................................................................................................317 30.2 block diagram .................................................................................................318 30.3 application block diagram ..............................................................................318 30.4 pin name list ..................................................................................................319 30.5 product dependencies ....................................................................................319 30.6 functional description .....................................................................................319 30.7 ssc application examples ..............................................................................332 30.8 synchronous serial controller (ssc) user interface ......................................334 31 timer/counter (tc) ........... .............. .............. .............. .............. ........... 357 31.1 overview .........................................................................................................357 31.2 block diagram .................................................................................................358 31.3 pin name list ..................................................................................................359 31.4 product dependencies ....................................................................................359 31.5 functional description .....................................................................................360 31.6 timer/counter (tc) user interface ..................................................................373 32 pulse width modulation c ontroller (pwm) . .............. .............. ........... 391 32.1 overview .........................................................................................................391 32.2 block diagram .................................................................................................391 32.3 i/o lines description .......................................................................................392 32.4 product dependencies ....................................................................................392 32.5 functional description .....................................................................................392 32.6 pulse width modulation (pwm) controller user interface .............................401 33 usb device port (udp) ....... .............. ............... .............. .............. ........ 411 33.1 overview .........................................................................................................411 33.2 block diagram .................................................................................................412 33.3 product dependencies ....................................................................................413 33.4 typical connection ..........................................................................................414 33.5 functional description .....................................................................................415 33.6 usb device port (udp) user interface ...........................................................429 34 multimedia card interface (m ci) ........... ................. ................ ............. 447 34.1 overview .........................................................................................................447 34.2 block diagram .................................................................................................448 34.3 application block diagram ..............................................................................448 34.4 pin name list .................................................................................................449 34.5 product dependencies ....................................................................................449
vii 6042e?atarm?14-dec-06 at91sam7a3 preliminary 34.6 bus topology ..................................................................................................449 34.7 multimedia card operations ............................................................................451 34.8 sd card operations ........................................................................................459 34.9 multimedia card interface (mci) user interface ..............................................460 35 analog-to-digital converte r (adc) ....... ................. ................ ............. 475 35.1 overview .........................................................................................................475 35.2 block diagram .................................................................................................475 35.3 signal description ...........................................................................................476 35.4 product dependencies ....................................................................................476 35.5 functional description .....................................................................................477 35.6 analog-to-digital converter (adc) user interface ...........................................482 36 controller area network (c an) ............ ................. ................ ............. 493 36.1 overview .........................................................................................................493 36.2 block diagram .................................................................................................494 36.3 application block diagram ..............................................................................494 36.4 i/o lines description ......................................................................................495 36.5 product dependencies ....................................................................................495 36.6 can controller features .................................................................................496 36.7 functional description .....................................................................................508 36.8 controller area network (can) user interface ...............................................521 37 at91sam7a3 electrical characteristics ... ................ .............. ........... 549 37.1 absolute maximum ratings .............................................................................549 37.2 dc characteristics ..........................................................................................549 37.3 power consumption ........................................................................................551 37.4 crystal oscillator characteristics .....................................................................553 37.5 pll characteristics .........................................................................................556 37.6 usb transceiver characteristics .....................................................................557 37.7 analog-to-digital converter characteristics ....................................................559 37.8 ac characteristics ...........................................................................................560 38 at91sam7a3 mechanical characteristics . .............. .............. ........... 566 38.1 thermal considerations ..................................................................................566 38.2 package drawing ............................................................................................567 38.3 soldering profile ..............................................................................................569 39 at91sam7a3 ordering information .......... ................ .............. ........... 570
viii 6042e?atarm?14-dec-06 at91sam7a3 preliminary 40 errata ........... ................ ................ ................. ................ .............. ........... 571 40.1 marking ............................................................................................................571 40.2 at91sam7a3 errata - rev. a parts ...............................................................572 ................... ................. .............. .............. .............. .............. .............. ........... i table of contents.......... ................. ................ ................. ................ ........... i revision history.......... ................ ................. ................ ................. ........... ix
ix 6042e?atarm?14-dec-06 at91sam7a3 preliminary revision history version comments change request ref. 6042a 23-dec-2004 first issue 6042b 30-sep-2005 in ?features? , corrected number of battery backup registers in features. updated details of page programming time. 05-231 changed signal names vddin and vddio to vdd3v3 and vddout and vddcore to vdd1v8. removed signal names gndana, gndbu and gndpll in figure 2-1, ?at91sam7a3 block diagram? , table 3-1, ?signal description? and table 4-1, ?pinout in 100-lead lqfp package? . updated section 5.1, ?power supplies? with new signal names and new information. updated figure 5-1, ?3.3v system si ngle power supply schematics? with new signal names. updated section 8.1 ?embedded memories? on page 15 with correct lock region size. 05-440 updated section 8.3, ?embedded flash? with information on standby mode for flash. updated figure 9-1, ?system controller block diagram? with new signal names. corrected start and end addresses of gpbr in figure 9-2, ? system controller mapping?;. 05-233 updated chip id reference in section 9.6, ?debug unit? . updated figure 18-1 , ?shutdown controller block diagram? to remove rtc. 05-230 updated shdw_mr register with rttwken bit and definition. updated formula in definition of cptwkx pin in shdw_mr register. 05-235 updated shdw_sr register with rttwk bit and definition 05-016 updated information on fmcn bit: removed note, changed bit description in mc flash mode register . 05-380 added external interrupt source type to srctype bit in aic_smrx register. section debug unit updated to remove all references to force_nrst. updated bit descriptions for sramsiz and arch in debug unit chip id register. 05-115, 05-306, 05-307 pull-up resistor value changed to 10 ohm in section 26.4.1, ?pull-up resistor control? . iadrsiz[9:8] bit description changed in twi master mode register 05-057 iadr bit description changed in twi internal address register 05-060 txcomp bit description changed in twi status register 05-062 corrected error in text of section 29.5.3.5, ?parity? , in usart section. 05-067 corrected error in figure 29-17 , ?receiver behavior when operating with hardware handshaking? in usart section. 04-467 corrected error in figure 29-23 , ?irda modulation? in usart section. clock gating feature added in receive and transmit clock mode registers in ssc section. in section ?synchronous serial controller?, compare functions added. pwm, added note on polarity and alignment in section 32.5.3.3, ?changing the duty cycle or the period? .
x 6042e?atarm?14-dec-06 at91sam7a3 preliminary 6042b added section 32.5.3.4, ?interrupts? in pwm section. added warning regarding udp peripheral clock in pmc and udp_txcv register to ?power management? , ?usb device port (udp) user interface? and ?udp transceiver control register? 05-413 corrected reset state for udp_txvc register. 05-100 changed register names from usb_xx to udp_xx. 05-147 corrected bit name to read endburses in ?udp interrupt clear register? . 05-148 added missing bit ep5int in section 33.6.9, ?udp reset endpoint register? corrected pin names in figure 34-4, ?mmc bus connections (one slot)? , 05-194 corrected formula for entering power saving mode in multimedia card interface (mci). 04-489 changed govre bit description in section 35.6.6, ?adc status register? i 05-045 corrected typo in lpm bit description in section 36.8.1, ?can mode register? . 05-206 corrected and updated section 36.6.4.1 , ?can bit timing configuration? ; corrected figure 36-5 , ?can bit timing? ; updated ?example of bit timing determination for can baudrate of 500 kbit/s:? , added figure 36-6, ?can resynchronization? . 05-336, 05-420 corrected and updated section 36.8.6, ?can baudrate register? 05-420 updated section 37., ?at91sam7a3 electrical characteristics? , section 38., ?at91sam7a3 mechanical characteristics? and section 39., ?at91sam7a3 ordering information? . 6042c 21-nov-2005 section 40., ?errata? added to datasheet. replaces at91sa m7a3 errata sheet atmel 6145 05-524 evolution in ip blocks: pmc, section 24.7, ?programming sequence? change to some text and code. spi, change to figure 27-1, ?block diagram? , changes in section 27.7, ?serial periphe ral interface (spi) user interface? udp , warning added to section 33.3.2, ?power management? , section 33.6, ?usb device port (udp) user interface? and section 33.6.12, ?udp tran sceiver control register? 05-525 change to register bit-field descriptions: ?svmst0: saved pdc abort source? and ?svmst1: saved arm7tdmi abort source? in the ?mc abort status register? 05-527 pll conditions changed in table 37-12, ?phase lock loop characteristics? 05-528 in features and global: ?embeddedice ? in-circuit emulation, debug co mmunication channel support? embeddedice to replace usage of ?embedded in-ciruit emulator? sjo legal 6042d 04-apr-2006 errata added: section 40.2.6.4, ?spi: spck behavior in master mode? , section 40.2.8.2, ?twi: possible receive holding register corruption? , section 40.2.8.3, ?twi: nack status bit lost? and section 40.2.8.4, ?twi: disabling does not operate correctly? reference to srctype field corrected in section 22.7.3.1, ?priority controller? in aic section. #2454 #2512 version comments change request ref.
xi 6042e?atarm?14-dec-06 at91sam7a3 preliminary version 6042e comments change request ref. section 4.1, ?100-lead lqfp package outline? replaces mechanical overview, figure 4-1, ?100-lead lqfp outline (top view)? replaced. peripheral and system controller memory maps consolidated in figure 8-1 on page 16 . table 11-1, ?peripheral identifiers,? on page 29 , sysirq changed to sysc. table 3-1, ?signal description,? on page 5 , shdw and fwup, comments updated figure 8-2, ?internal memory mapping? reference to boot memory removed. 3180 rfo debug and test: section 13.6.3, ?debug unit? debug unit chip id value is 0x260a0941 rfo rstc: section 14.3.1, ?reset controller overview? , updated with crystal oscillator effect on startup counter. 3005 rtt: added note to section 15.3, ?functional description? 2522 wdt: wv changed to wdv in section 17.2, ?block diagram? and in section 17.3, ?functional description? , and the 6th and 7th paragraph rewritten on page 78 beginning with ?to prevent a software deadlock 3002 pdc: section 21.1, ?overview? , user interface description updated. aic: ?register mapping? on page 140 , footnote (2) added in reference to pid2...pid31 bit fields. 2548 pmc: section 23.3.1, ?main oscillator connections? , updated. added a note defining pidx to section 24.9.4, ?pmc peripheral clock enable register? , section 24.9.5, ?pmc peripheral clock disable register? and section 24.9.6, ?pmc peripheral clock status register? 3282 2468 dbgu: section 25.5.10, ?debug unit chip id register? update to the table in ?arch: architecture identifier? on page 203 . figure 25-1, ?debug unit functional block diagram? , ?ice_nreset? signal name replaced by pad name ?power-on reset?. 1744/05-459 2832 pio: figure 26-3, ?i/o line control logic? updated, 3053 spi: figure 27-9, ?slave mode functional block diagram? , fload removed. section 27.6.3, ?mas ter mode operations? , update to spi_rdr information section 27.7.1, ?spi control register? , added information to bit description ?swrst: spi soft ware reset? on page 245 . section 27.7.9, ?spi chip select register? , corrected equation in ?dlybct: delay between consecutive transfers? on page 256 . section 27.6.3.8, ?mode fault detection? , updated. 1542 1543 1676 twi: section 28.6, ?two-wire inte rface (twi) user interface? unre and ovre bit fields removed from twi status and interrupt register tables. 2470
xii 6042e?atarm?14-dec-06 at91sam7a3 preliminary section 29., ?universal synchronous asyn chronous receiver transceiver (usart)? extensive update since last version, should be considered care fully. updates include the following: section 29.5.4.1, ?iso 7816 mode overview? , clarification of par configuration. section 29.4.1, ?i/o lines? , text concerning txd line added. table 29-3, ?binary and decimal values for di? and table 29-4, ?binary and decimal values for fi,? on page 280 , di and fi properly referenced in titles. figure 29-24, ?irda demodulator operations? , firgure modified. table 29-2, ?baud rate example (over = 0)? , last two lines of table removed. section 29.5.3.2, ?a synchronous receiver? , change to second sentence in fourth paragraph ?for the synchronization mechanism.....? section 29.5.3.8, ?r eceiver time-out? , list of user options rewritten. section 29.6.1, ?usart control register? sttto bit function related to timeout in us_csr register. section 29.6.6, ?usart c hannel status register? timeout bit function re lated to sttto in us_cr register 1552 rfo review 2942 3023 tc: added table 31-1, ?timer counter clock assignment,? on page 357 . section 31.5.4, ?external event/trigger conditions? ?....(eevt = 0), tiob is no longer used as an output and the compare register b is not used to ge nerate waveforms and subsequently no irqs. the note (1) attached to the register bit description ?eevt: external event selection? on page 380 further clarifies this condition. figure 31-2, ?clock chaining selection? , added to demonstrate clock chaining. 2470 2704 3342 pwm: section 32.5.3.3, ?changing the duty cycle or the period? , update to info on waveform generation. 1677 section 33., ?usb device port (udp)? , extensive update since last version, should be considered carefully. updates include, but are not limited to the following: figure 33-2 on page 414 updated. section 33.4.1, ?usb device transceiver? and section 33.4.2, ?vbus monitoring? added. section 33.5.1.2, ?usb bus transactions? updated. section 33.5.1.3, ?usb transfer event definitions? , updated with endpoint information. section 33.5.2.2, ?data in transaction? endpoint use updated. section 33.5.2, ?handling transactions with usb v2.0 device peripheral? , section reworked, warnings added. section 33.5.3, ?contro lling device states? section reworked. section 33.5.3.1, ?not powered state? and section 33.5.3.2, ?entering attached state? have been added. section 33.6.2, ?udp global state register? , updated. section 33.6.10, ?udp endpoint control and status register? , updated. rfo rework + 2259,2542, 2544, 2826, 2905, 3014, 3048, 3055, section 34., ?multimedia card interface (mci)? figure 34-8, ?read functional flow diagram? , update to flow chart. figure 34-9, ?write functional flow diagram? , update to flow chart. figure 34-10, ?multiple write functional flow diagram? , added flow chart. section 34.9.10, ?mci status register? , update to descriptions of blke and notbusy flags. section 34.9.10, ?mci status register? , added reset information on dcrce and dtoe bits. 2462 2593 adc: editor use of variables in register tables added, section 35.5.7, ?adc timings? in the warning: ?see adc characteristics....?, typo fixed in the block diagram, figure 35-1 on page 475 , dedicated and i/o line multiplexed analog inputs differentiated. 1749 2830 3052 version 6042e comments change request ref.
xiii 6042e?atarm?14-dec-06 at91sam7a3 preliminary can: section 36.6.2.1 ?message acceptance procedure? on page 496 update to message acceptance example section 36.8.17, ?can message data low register? updated mdl bit description, and section 36.8.18, ?can message data high register? new information on byte priority added to both registers. update to specify allowed values for brp field on page 501 and section 36.8.6, ?can baudrate register? 2295/2296 2467 2597 electrical characteristics: figure 37-2, ?dc characteristics? , erase pin removed from table. table 37-6, ?typical power consumption by peripheral in active mode? , consumption values updated, arm7 and syst peripherals added to table, adc removed. table 37-8, ?main oscillator characteristics? , updated. table 37-9, ?crystal characteristics? , added. table 37-10, ?xin clock electrical characteristics? , updated. table 37-21, ?spi timings? , ?min? updated for spi 0 and spi 1 note 2 added to table, text added after table. rfo section 40. ?errata? on page 571 added section 40.1, ?marking? 3180 section 40.2.2.1, ?pio: leakage on pb14 - pb29? , the leakage can be 25 a in worst case.... the following errata have been added. section 40.2.1.1, ?mci: data timeout error flag? section 40.2.1.2, ?mci: str eam command not supported? section 40.2.1.3, ?mci: data fifo and status bits? section 40.2.1.4, ?mci: data fifo problem with pdc? section 40.2.5.1, ?rtt: possible event loss when reading rtt_sr? section 40.2.8, ?two-wire interface (twi)? behavior of ovre bit removed from twi errata. (2470) section 40.2.8.5, ?twi: software reset? section 40.2.9.1, ?usart: hardware handshaking ? two characters sent? section 40.2.9.2, ?usart: xo ff character bad behavior? section 40.2.6.5, ?spi: chip select and fixed mode? section 40.2.6.6, ?spi: baudrate set to 1? section 40.2.6.7, ? spi: disable issue? section 40.2.6.8, ?spi: disable in slave mode? section 40.2.6.9, ?spi: so ftware reset and spien bit? section 40.2.6.10, ?spi: csaat = 1 and delay? rfo 2870/2873 version 6042e comments change request ref.
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