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| features ? high-performance, low-power avr ? 8-bit microcontroller ? advanced risc architecture ? 131 powerful instructions ? most single-clock cycle execution ? 32 x 8 general purpose working registers ? fully static operation ? up to 16 mips throughput at 16 mhz ? on-chip 2-cycle multiplier ? high endurance non-volatile memory segments ? 16k bytes of in-system self-p rogrammable flash program memory ? 512 bytes eeprom ? 1k bytes internal sram ? write/erase cycles: 10,000 flash/100,000 eeprom ? data retention: 20 years at 85c/100 years at 25c (1) ? optional boot code section with independent lock bits in-system programming by on-chip boot program true read-while-w rite operation ? up to 64k bytes optional external memory space ? programming lock for software security ? jtag (ieee std. 1149.1 compliant) interface ? boundary-scan capabilities a ccording to the jtag standard ? extensive on-chip debug support ? programming of flash, eeprom, fuses, an d lock bits through the jtag interface ? peripheral features ? two 8-bit timer/counters with se parate prescalers and compare modes ? two 16-bit timer/counters with separa te prescalers, compare modes, and capture modes ? real time counter with separate oscillator ? six pwm channels ? dual programmable serial usarts ? master/slave spi serial interface ? programmable watchdog timer with separate on-chip oscillator ? on-chip analog comparator ? special microcontroller features ? power-on reset and programmable brown-out detection ? internal calibrated rc oscillator ? external and internal interrupt sources ? five sleep modes: idle, power-save, powe r-down, standby, and extended standby ? i/o and packages ? 35 programmable i/o lines ? 40-pin pdip, 44-lead tqfp, and 44-pad mlf ? operating voltages ? 1.8 - 5.5v for atmega162v ? 2.7 - 5.5v for atmega162 ? speed grades ? 0 - 8 mhz for atmega162v (see figure 113 on page 266 ) ? 0 - 16 mhz for atmega162 (see figure 114 on page 266 ) 8-bit microcontroller with 16k bytes in-system programmable flash atmega162 atmega162 v 2513k?avr?07/09
2 2513k?avr?07/09 atmega162/v pin configurations figure 1. pinout atmega162 disclaimer typical values contained in this datasheet ar e based on simulations and characterization of other avr microcontrollers manufactured on the same process technology. min and max values will be available after the device is characterized. (oc0/t0) pb0 (oc2/t1) pb1 (rxd1/ain0) pb2 (txd1/ain1) pb3 (ss/oc3b) pb4 (mosi) pb5 (miso) pb6 (sck) pb7 reset (rxd0) pd0 (txd0) pd1 (int0/xck1) pd2 (int1/icp3) pd3 (tosc1/xck0/oc3a) pd4 (oc1a/tosc2) pd5 (wr) pd6 (rd) pd7 xtal2 xtal1 gnd vcc pa0 (ad0/pcint0) pa1 (ad1/pcint1) pa2 (ad2/pcint2) pa3 (ad3/pcint3) pa4 (ad4/pcint4) pa5 (ad5/pcint5) pa6 (ad6/pcint6) pa7 (ad7/pcint7) pe0 (icp1/int2) pe1 (ale) pe2 (oc1b) pc7 (a15/tdi/pcint15) pc6 (a14/tdo/pcint14) pc5 (a13/tms/pcint13) pc4 (a12/tck/pcint12) pc3 (a11/pcint11) pc2 (a10/pcint10) pc1 (a9/pcint9) pc0 (a8/pcint8) pa4 (ad4/pcint4) pa5 (ad5/pcint5) pa6 (ad6/pcint6) pa7 (ad7/pcint7) pe0 (icp1/int2) gnd pe1 (ale) pe2 (oc1b) pc7 (a15/tdi/pcint15) pc6 (a14/tdo/pcint14) pc5 (a13/tms/pcint13) (mosi) pb5 (miso) pb6 (sck) pb7 reset (rxd0) pd0 vcc (txd0) pd1 (int0/xck1) pd2 (int1/icp3) pd3 (tosc1/xck0/oc3a) pd4 (oc1a/tosc2) pd5 (wr) pd6 (rd) pd7 xtal2 xtal1 gnd vcc (a8/pcint8) pc0 (a9/pcint9) pc1 (a10/pcint10) pc2 (a11/pcint11) pc3 (tck/a12/pcint12) pc4 pb4 (ss/oc3b) pb3 (txd1/ain1) pb2 (rxd1/ain0) pb1 (oc2/t1) pb0 (oc0/t0) gnd vcc pa0 (ad0/pcint0) pa1 (ad1/pcint1) pa2 (ad2/pcint2) pa3 (ad3/pcint3) 40 39 38 37 36 35 34 33 32 31 30 29 28 27 26 25 24 23 22 21 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 pdip 1 2 3 4 5 6 7 8 9 10 11 12 14 16 18 20 22 13 15 17 19 21 33 32 31 30 29 28 27 26 25 24 23 44 42 40 38 36 34 43 41 39 37 35 tqfp/mlf note: mlf bottom pad should be soldered to ground. 3 2513k?avr?07/09 atmega162/v overview the atmega162 is a low-power cmos 8-bit microcontroller based on the avr enhanced risc architecture. by executing powerful instructions in a single clock cycle, the atmega162 achieves throughputs approaching 1 mips per mhz allowing the system designer to optimize power consumption versus processing speed. block diagram figure 2. block diagram internal oscillator oscillator watchdog timer mcu ctrl. & timing oscillator timers/ counters interrupt unit stack pointer eeprom sram status register usart0 program counter program flash instruction register instruction decoder programming logic spi comp. interface porta drivers/buffers porta digital interface general purpose registers x y z alu + - portc drivers/buffers portc digital interface portb digital interface portb drivers/buffers portd digital interface portd drivers/buffers xtal1 xtal2 reset control lines vcc gnd pa0 - pa7 pc0 - pc7 pd0 - pd7 pb0 - pb7 avr cpu internal calibrated oscillator porte drivers/ buffers porte digital interface pe0 - pe2 usart1 4 2513k?avr?07/09 atmega162/v the avr core combines a rich instruction set with 32 general purpose working registers. all the 32 registers are directly connected to the arithmetic logic unit (alu), allowing two independent registers to be accessed in one single instruction executed in one clock cycle. the resulting architecture is more code efficient while achiev ing throughputs up to ten times faster than con- ventional cisc microcontrollers. the atmega162 provides the following features: 16k bytes of in-system programmable flash with read-while-write capabilities, 512 byte s eeprom, 1k bytes sram, an external memory interface, 35 general purpose i/o lines, 32 general purpose working registers, a jtag interface for boundary-scan, on-chip debugging support and programming, four flexible timer/counters with compare modes, internal and external interrupts, two serial programmable usarts, a pro- grammable watchdog timer with internal oscillator, an spi serial port, and five software selectable power saving modes. the idle mode stops the cpu while allowing the sram, timer/counters, spi port, and interrupt system to continue functioning. the power-down mode saves the register contents but freezes the oscilla tor, disabling all other chip functions until the next interrupt or hardware reset. in power-save mode, the asynchronous timer continues to run, allowing the user to maintain a timer base while the rest of the device is sleeping. in standby mode, the crystal/ resonator oscillator is ru nning while the rest of the device is sleeping. this allows very fast start-up combined with low-power consumption. in extended standby mode, both the main oscillator and the asynchronous timer continue to run. the device is manufactured using atmel?s high density non-volatile memory technology. the on-chip isp flash allows the program memory to be reprogrammed in-system through an spi serial interface, by a conventi onal non-volatile memory programmer, or by an on-chip boot pro- gram running on the avr core. the boot pr ogram can use any interface to download the application prog ram in the application fl ash memory. software in the boot flash section will continue to run while the application flash se ction is updated, providing true read-while-write operation. by combining an 8-bit risc cpu with in-system self-programmable flash on a monolithic chip, the atmel atmega162 is a powerful microcontroller that provides a highly flexi- ble and cost effective solution to many embedded control applications. the atmega162 avr is supported with a full suite of program and system development tools including: c compilers, macro assemblers, program debugger/simulators, in-circuit emulators, and evaluation kits. atmega161 and atmega162 compatibility the atmega162 is a highly complex microcontroller where the number of i/o locations super- sedes the 64 i/o locations reserved in the avr instruction set. to ensure back-ward compatibility with the atm ega161, all i/o location s present in atmega161 have the same loca- tions in atmega162. some additional i/o locati ons are added in an extended i/o space starting from 0x60 to 0xff, (i.e., in the atmega162 internal ram space). these locations can be reached by using ld/lds/ldd and st/sts/std instructions only, not by using in and out instructions. the relocation of the internal ram space may st ill be a problem for atmega161 users. also, the increased number of interrupt vectors might be a problem if the code uses absolute addresses. to solve these problems, an atmega161 compatibility mode can be selected by programming the fuse m161c. in this mode, none of the functions in the extended i/o space are in use, so the internal ram is lo cated as in atmega161. also, the extended inter- rupt vec-tors are removed. the atmega162 is 100% pin compatible with atmega161, and can replace the atmega161 on current printed circuit boards. however, the location of fuse bits and the electrical characteristics differs between the two devices. atmega161 compatibility mode programming the m161c will chang e the following functionality: ? the extended i/o map will be configured as internal ram once the m161c fuse is programmed. 5 2513k?avr?07/09 atmega162/v ? the timed sequence for changing the watchdog time-out period is disabled. see ?timed sequences for changing the configuration of the watchdog timer? on page 56 for details. ? the double buffering of the usart receive registers is disabled. see ?avr usart vs. avr uart ? compatibility? on page 168 for details. ? pin change interrupts are not supported (control registers are located in extended i/o). ? one 16 bits timer/counter (timer/counter1) only. timer/counter3 is not accessible. note that the shared ubrrhi register in atmega161 is split into two separate registers in atmega162, ubrr0h and ubrr1h. th e location of these registers will not be affected by the atmega161 com patibility fuse. pin descriptions vcc digital supply voltage gnd ground port a (pa7..pa0) port a is an 8-bit bi-directional i/o port with internal pull-up resistors (selected for each bit). the port a output buffers have symmetrical drive characteristics with both high sink and source capability. when pins pa0 to pa7 are used as inputs and are externally pulled low, they will source current if the internal pull-up resistors are activated. the port a pins are tri-stated when a reset condition becomes active, even if the clock is not running. port a also serves the functions of various special features of the atmega162 as listed on page 72 . port b (pb7..pb0) port b is an 8-bit bi-directional i/o port with internal pull-up resistors (selected for each bit). the port b output buffers have symmetrical drive characteristics with both high sink and source capability. as inputs, port b pi ns that are externally pulled low will source current if the pull-up resistors are activated. the port b pins are tri-stated when a reset condition becomes active, even if the clock is not running. port b also serves the functions of various special features of the atmega162 as listed on page 72 . port c (pc7..pc0) port c is an 8-bit bi-directional i/o port with internal pull-up resistors (selected for each bit). the port c output buffers have symmetrical drive c haracteristics with bot h high sink and source capability. as inputs, port c pi ns that are externally pulled lo w will source current if the pull-up resistors are activated. the port c pins are tri-stated when a reset condition becomes active, even if the clock is not running. if the jtag interface is enabled, the pull-up resistors on pins pc7(tdi), pc5(tms) and pc 4(tck) will be activated even if a reset occurs. port c also serves the functions of the jtag interface and other special features of the atmega162 as listed on page 75 . 6 2513k?avr?07/09 atmega162/v port d (pd7..pd0) port d is an 8-bit bi-directional i/o port with internal pull-up resistors (selected for each bit). the port d output buffers have symmetrical drive c haracteristics with bot h high sink and source capability. as inputs, port d pi ns that are externally pulled lo w will source current if the pull-up resistors are activated. the port d pins are tri-stated when a reset condition becomes active, even if the clock is not running. port d also serves the functions of various sp ecial features of the atmega162 as listed on page 78 . port e(pe2..pe0) port e is an 3-bit bi-directional i/o port with internal pull-up resistors (selected for each bit). the port e output buffers have symmetrical drive characteristics with both high sink and source capability. as inputs, port e pi ns that are externally pulled low will source current if the pull-up resistors are activated. the port e pins are tri-stated when a reset condition becomes active, even if the clock is not running. port e also serves the functions of various special features of the atmega162 as listed on page 81 . reset reset input. a low level on this pin for longer than the minimum pulse length will generate a reset, even if the clock is not running. the minimum pulse length is given in table 18 on page 48 . shorter pulses are not guaranteed to generate a reset. xtal1 input to the inverting oscillato r amplifier and input to the in ternal clock operating circuit. xtal2 output from the invert ing oscillator amplifier. 7 2513k?avr?07/09 atmega162/v resources a comprehensive set of development tools, app lication notes and datasheets are available for download on http:// www.atmel.com/avr. note: 1. data retention reliability qualification results show that the pr ojected data retention failure rate is much less than 1 ppm over 20 years at 85c or 100 years at 25c. 8 2513k?avr?07/09 atmega162/v about code examples this documentation contains simple code examples that briefly show how to use various parts of the device. these code examples assume that the part specific header file is included before compilation. be aware that not all c compiler vendors include bit definitions in the header files and interrupt handling in c is compiler dependent. please confirm with the c compiler documen- tation for more details. 9 2513k?avr?07/09 atmega162/v avr cpu core introduction this section discusses the avr core architecture in general. the main function of the cpu core is to ensure correct program execution. the cpu must therefore be able to access memories, perform calculations, control peripherals, and handle interrupts. architectural overview figure 3. block diagram of the avr architecture in order to maximize performance and parallelism, the avr uses a harvard architecture ? with separate memories and buses for program and data. instructions in the program memory are executed with a single level pipelining. while one instruction is being executed, the next instruc- tion is pre-fetched from the program memory. this concept enables instructions to be executed in every clock cycle. the program memory is in-system reprogrammable flash memory. the fast-access register file contains 32 x 8-bit general purpose working registers with a single clock cycle access time. this allows single-cycle ar ithmetic logic unit (alu ) operation. in a typ- ical alu operation, two operands are output from the register file, the operation is executed, and the result is stored back in the register file ? in one clock cycle. six of the 32 registers can be used as three 16-b it indirect address register pointers for data space addressing ? enabling efficient address calculations. one of the these address pointers flash program memory instruction register instruction decoder program counter control lines 32 x 8 general purpose registrers alu status and control i/o lines eeprom data bus 8-bit data sram direct addressing indirect addressing interrupt unit spi unit watchdog timer analog comparator i/o module 2 i/o module1 i/o module n 10 2513k?avr?07/09 atmega162/v can also be used as an address pointer for look up tables in flash program memory. these added function registers are the 16-bit x-, y-, and z-register, described later in this section. the alu supports arithmetic and logic operations between registers or between a constant and a register. single register operations can also be executed in the alu. after an arithmetic opera- tion, the status register is updated to reflect information about the result of the operation. program flow is provided by conditional and uncon ditional jump and call instructions, able to directly address the whole address space. most avr instructions have a single 16-bit word for- mat. every program memory address contains a 16- or 32-bit instruction. program flash memory space is divided in two sections, the boot program section and the application program section. both sections have dedicated lock bits for write and read/write protection. the spm instruction that writes into the application flash memory section must reside in the boot program section. during interrupts and subroutine calls, the return address program counter (pc) is stored on the stack. the stack is effectively allocated in the general data sram, and consequently the stack size is only limited by the to tal sram size and the usage of the sram. all user programs must initialize the sp in the reset routine (before subroutines or interrupts are executed). the stack pointer sp is read/write accessible in the i/o space. the data sram can easily be accessed through the five different addressing modes supported in the avr architecture. the memory spaces in the avr architecture are all linear and regular memory maps. a flexible interrupt module has its control r egisters in the i/o space with an additional global interrupt enable bit in the status register. all interrupts have a separate interrupt vector in the interrupt vector table. the interrupts have priority in accordance with their interrupt vector posi- tion. the lower the interrupt vector address, the higher the priority. the i/o memory space contains 64 addresses for cpu peripheral functi ons as control regis- ters, spi, and other i/o functions. the i/o memory can be accessed directly, or as the data space locations following those of the register file, 0x20 - 0x5f. alu ? arithmetic logic unit the high-performance avr alu operates in dire ct connection with all the 32 general purpose working registers. within a single clock cycle, arithmetic operations between general purpose registers or between a register and an immediate are executed. the alu operations are divided into three main categories ? arithmetic, logical, and bit-functions. some implementations of the architecture also provide a powerful multiplier supporting both signed/unsigned multiplication and fractional format. see the ?instruction set? section for a detailed description. status register the status register contains information about the result of the most recently executed arithme- tic instruction. this information can be used for altering program flow in order to perform conditional operations. note that the status register is updated after all alu operations, as specified in the instruction set reference. this will in many cases remove the need for using the dedicated compare instructions, resulting in faster and more compact code. the status register is not automatically stored when entering an interrupt routine and restored when returning from an interrupt. this must be handled by software. the avr status register ? sreg ? is defined as: bit 76543210 i t h s v n z c sreg read/write r/w r/w r/w r/w r/w r/w r/w r/w initial value 0 0 0 0 0 0 0 0 11 2513k?avr?07/09 atmega162/v ? bit 7 ? i: global interrupt enable the global interrupt enable bit must be set for th e interrupts to be enabled. the individual inter- rupt enable control is then performed in separate control registers. if the global interrupt enable register is cleared, none of the interrupts are enabled independent of the individual interrupt enable settings. the i-bit is cleared by hardware after an interrupt has occurred, and is set by the reti instruction to enable subsequent interrupts. the i-bit can also be set and cleared by the application with the sei and cli instructions, as described in the instruction set reference. ? bit 6 ? t: bit copy storage the bit copy instructions bld (bit load) and bst (bit store) use the t bit as source or destina- tion for the operated bit. a bit from a register in the register file can be copied into t by the bst instruction, and a bit in t can be copied into a bit in a register in the register file by the bld instruction. ? bit 5 ? h: half carry flag the half carry flag h indicates a half carry in so me arithmetic operations. half carry is useful in bcd arithmetic. see the ?instruction set description? for detailed information. ? bit 4 ? s: sign bit, s = n v the s-bit is always an exclusive or between the negative flag n and the two?s complement overflow flag v. see the ?instruction set description? for detailed information. ? bit 3 ? v: two?s complement overflow flag the two?s complement overflow flag v suppor ts two?s complement arithmetics. see the ?instruction set description? for detailed information. ? bit 2 ? n: negative flag the negative flag n indicates a negative result in an arithmetic or logic operation. see the ?instruction set description? for detailed information. ? bit 1 ? z: zero flag the zero flag z indicates a zero result in an arithmetic or logic operation. see the ?instruction set description? for detailed information. ? bit 0 ? c: carry flag the carry flag c indicates a carry in an arithmetic or logic operation. see the ?instruction set description? for de tailed information. 12 2513k?avr?07/09 atmega162/v general purpose register file the register file is optimized for the avr enhanc ed risc instruction set. in order to achieve the required performance and flex ibility, the following in put/output schemes ar e supported by the register file: ? one 8-bit output operand and one 8-bit result input ? two 8-bit output operands and one 8-bit result input ? two 8-bit output operands and one 16-bit result input ? one 16-bit output operand and one 16-bit result input figure 4 shows the structure of the 32 general purpose working registers in the cpu. figure 4. avr cpu general purpose working registers most of the instructions operating on the register file have direct access to all registers, and most of them are single cycle instructions. as shown in figure 4 , each register is also assigned a data memory address, mapping them directly into the first 32 locations of the user data space. although not being physically imple- mented as sram locations, this memory organization provides great flexibility in access of the registers, as the x-, y-, and z-pointer registers can be set to index any register in the file. 7 0 addr. r0 0x00 r1 0x01 r2 0x02 ? r13 0x0d general r14 0x0e purpose r15 0x0f working r16 0x10 registers r17 0x11 ? r26 0x1a x-register low byte r27 0x1b x-register high byte r28 0x1c y-register low byte r29 0x1d y-register high byte r30 0x1e z-register low byte r31 0x1f z-register high byte 13 2513k?avr?07/09 atmega162/v the x-register, y- register, and z-register the registers r26..r31 have some added functions to their general purpose usage. these reg- isters are 16-bit address pointers for indirect addressing of the data space. the three indirect address registers x, y, and z are defined as described in figure 5 . figure 5. the x-, y-, and z-registers in the different addressing modes these address registers have functions as fixed displacement, automatic increment, and automatic decrement (see the instruction set reference for details). stack pointer the stack is mainly used for storing temporary data, for storing local variables and for storing return addresses after interrupts and subroutine calls. the stack pointer register always points to the top of the stack. note that the stack is implemented as growing from higher memory loca- tions to lower memory locations. this implies that a stack push command decreases the stack pointer. the stack pointer points to the data sram stack area where the subroutine and interrupt stacks are located. this stack space in the data sram must be defined by the program before any subroutine calls are executed or interrupts are enabled. the stack pointer must be set to point above 0x60. the stack pointer is decrement ed by one when data is pushed onto the stack with the push instruction, and it is decremented by two when the return address is pushed onto the stack with subroutine call or interrupt. the stack pointer is incremented by one when data is popped from the stack with the pop instruction, and it is incremented by two when data is popped from the stack with return from subroutine ret or return from interrupt reti. the avr stack pointer is implemented as two 8- bit registers in the i/o space. the number of bits actually used is implementation dependent. note that the data space in some implementa- tions of the avr architecture is so small that only spl is needed. in this case, the sph register will not be present. 15 xh xl 0 x - register 7 0 7 0 r27 (0x1b) r26 (0x1a) 15 yh yl 0 y - register 7 0 7 0 r29 (0x1d) r28 (0x1c) 15 zh zl 0 z - register 7 0 7 0 r31 (0x1f) r30 (0x1e) bit 151413121110 9 8 sp15 sp14 sp13 sp12 sp11 sp10 sp9 sp8 sph sp7 sp6 sp5 sp4 sp3 sp2 sp1 sp0 spl 76543210 read/write r/w r/w r/w r/w r/w r/w r/w r/w r/w r/w r/w r/w r/w r/w r/w r/w initial value 0 0 0 0 0 0 0 0 00000000 14 2513k?avr?07/09 atmega162/v instruction execution timing this section describes the general access timi ng concepts for instruction execution. the avr cpu is driven by the cpu clock clk cpu , directly generated from the selected clock source for the chip. no internal clo ck division is used. figure 6 shows the parallel instruction fetches and instruction executions enabled by the har- vard architecture and the fast-access register file concept. this is the basic pipelining concept to obtain up to 1 mips per mhz with the corr esponding unique results for functions per cost, functions per clocks, and functions per power-unit. figure 6. the parallel instruction fetches and instruction executions figure 7 shows the internal timing concept for the register file. in a single clock cycle an alu operation using two register operands is executed, and the result is stored back to the destina- tion register. figure 7. single cycle alu operation reset and interrupt handling the avr provides several different interrupt sources. these interrupts and the separate reset vector each have a separate program vector in the program memory space. all interrupts are assigned individual enable bits which must be written logic one together with the global interrupt enable bit in the status register in orde r to enable the interrupt. depending on the program counter value, interrupts may be automatically disabled when boot lock bits blb02 or blb12 are programmed. this feature improves software security. see the section ?memory program- ming? on page 231 for details. the lowest addresses in the program memory space are by default defined as the reset and interrupt vectors. the complete list of vectors is shown in ?interrupts? on page 57 . the list also determines the priority levels of the different interrupts. the lower the address the higher is the priority level. reset has the highest priority, and next is int0 ? the external interrupt request 0. the interrupt vectors can be moved to the start of the boot flash section by setting the ivsel bit in the general interrupt control register (gicr). refer to ?interrupts? on page 57 for more information. the reset vector can also be moved to the start of the boot flash section by pro- clk 1st instruction fetch 1st instruction execute 2nd instruction fetch 2nd instruction execute 3rd instruction fetch 3rd instruction execute 4th instruction fetch t1 t2 t3 t4 cpu total execution time register operands fetch alu operation execute result write back t1 t2 t3 t4 clk cpu 15 2513k?avr?07/09 atmega162/v gramming the bootrst fuse, see ?boot loader support ? read-while-write self- programming? on page 217 . when an interrupt occurs, the global interrupt enable i-bit is cleared and all interrupts are dis- abled. the user software can write logic one to the i-bit to enable nested interrupts. all enabled interrupts can then interrupt the current interrupt routine. the i-bit is automatically set when a return from interrupt instruction ? reti ? is executed. there are basically two types of interrupts. the fi rst type is triggered by an event that sets the interrupt flag. for these interrupts, the program counter is vectored to the actual interrupt vec- tor in order to execute the interrupt handling routine, and hardware clears the corresponding interrupt flag. interrupt flags can also be cleared by writing a logic one to the flag bit position(s) to be cleared. if an interrupt condition occurs while the corresponding interrupt enable bit is cleared, the interrupt fl ag will be set and remember ed until the interrupt is enabled, or the flag is cleared by software. similarly, if one or more interrupt conditions occur while the global interrupt enable bit is cleared, the corresponding interrupt flag(s) will be set and remembered until the global interrupt enable bit is set, and will then be exec uted by order of priority. the second type of interrupts will trigger as long as the interrupt condition is present. these interrupts do not necessarily have interrupt flags. if the interrupt condition disappears before the interrupt is enabled, the in terrupt will not be triggered. when the avr exits from an inte rrupt, it will always retu rn to the main pr ogram and execute one more instruction before any pending interrupt is served. note that the status register is not automatica lly stored when entering an interrupt routine, nor restored when returning from an interrupt routine. this must be handled by software. when using the cli instruction to disable interrupts, the interrup ts will be immediately disabled. no interrupt will be executed af ter the cli instruction, even if it occurs simultaneously with the cli instruction. the following example shows how this can be used to avoid interrupts during the timed eeprom write sequence. assembly code example in r16, sreg ; store sreg value cli ; disable interrupts during timed sequence sbi eecr, eemwe ; start eeprom write sbi eecr, eewe out sreg, r16 ; restore sreg value (i-bit) c code example char csreg; csreg = sreg; /* store sreg value */ /* disable interrupts during timed sequence */ _cli(); eecr |= (1< 17 2513k?avr?07/09 atmega162/v avr atmega162 memories this section describes the different memories in the atmega162. the avr architecture has two main memory spaces, the data memory and t he program memory space. in addition, the atmega162 featur es an eeprom memory for data storage. all three memory sp aces are linear and regular. in-system reprogrammable flash program memory the atmega162 contains 16k bytes on-chip in-system reprogrammable flash memory for program storage. since all avr instructions are 16 or 32 bits wide, the flash is organized as 8k x 16. for software security, the flash program memory space is divided into two sections, boot program section and application program section. the flash memory has an endurance of at least 10,000 write/erase cycles. the atmega162 program counter (pc) is 13 bits wide, thus addressing the 8k program memory locations. the operation of boot program section and associated boot lock bits for software protection are described in detail in ?boot loader support ? read-while-write self-programming? on page 217 . ?memory programming? on page 231 contains a detailed description on flash data serial down- loading using the spi pins or the jtag interface. constant tables can be allocated within the entire program memory address space (see the lpm ? load program memory instruction description). timing diagrams for instruction fetch and execution are presented in ?instruction execution tim- ing? on page 14 . figure 8. program memory map (1) note: 1. the address reflects word addresses. 0x0000 0x1fff program memory application flash section boot flash section 18 2513k?avr?07/09 atmega162/v sram data memory figure 9 shows how the atmega162 sram memory is organized. memory configuration b refers to the atmega161 compat ibility mode, configuration a to the non-compatible mode. the atmega162 is a complex microcontroller with more peripheral units than can be supported within the 64 location reserved in the opcode for the in and out instructions. for the extended i/o space from 0x60 - 0xff in sram, only the st/sts/std and ld/lds/ldd instructions can be used. the extended i/o space does not ex ist when the atmega162 is in the atmega161 compatibility mode. in normal mode, the first 1280 data memory locations address both the register file, the i/o memory, extended i/o memory, and the internal data sram. the first 32 locations address the register file, the next 64 location the standard i/o memory, then 160 locations of extended i/o memory, and the next 1024 locations address the internal data sram. in atmega161 compatibilit y mode, the lower 1120 data memo ry locations addr ess the register file, the i/o memory, and the internal data sram. the first 96 locations address the register file and i/o memory, and the next 1024 locations address the internal data sram. an optional external data sr am can be used with the atmega1 62. this sram will occupy an area in the remaining address locations in the 64k address space. this area starts at the address following the internal sram. the register file, i/o, extended i/o and internal sram uses the occupies the lowest 1280 bytes in normal mode, and the lowest 1120 bytes in the atmega161 compatibility mode (ext ended i/o not presen t), so when using 64kb (65,536 bytes) of external memory, 64,256 bytes of external memory are available in normal mode, and 64,416 bytes in atmega1 61 compatibility mode. see ?external memory interface? on page 26 for details on how to take advantage of the external memory map. when the addresses accessing the sram memory space exceeds the internal data memory locations, the external data sram is accessed using the same instructions as for the internal data memory access. when the internal data memories are accessed, the read and write strobe pins (pd7 and pd6) are inactive during the w hole access cycle. external sram operation is enabled by setting the sre bit in the mcucr register. accessing external sram takes one additional clock cycle per byte compared to access of the internal sram. this means that the commands ld, st, lds, sts, ldd, std, push, and pop take one additional clock cycle. if the stack is placed in external sram, interrupts, subroutine calls and returns take three clock cycles extra because the 2-byte program counter is pushed and popped, and external memory access does not take advantage of the internal pipeline memory access. when external sram interface is used with wait-state, one-byte external access takes two, three, or four additional cl ock cycles for one, two, and three wait-states respectively. interrupt, subroutine calls and return s will need five, seven, or nine clock cycles more than specified in the instruction set manual for one, two, and three wait-states. the five different addressing modes for the data memory cover: direct, indirect with displace- ment, indirect, indirect with pre-decrement, and indirect with post-increment. in the register file, registers r26 to r31 feature the indirect addressing pointer registers. the direct addressing reaches the entire data space. the indirect with displacement mode reaches 63 address locations from the base address given by the y- or z-register. when using register indirect addressing modes with automatic pre-decrement and post-incre- ment, the address registers x, y, and z are decremented or incremented. the 32 general purpose working registers, 64 (+160) i/o registers, and the 1024 bytes of inter- nal data sram in the atmega162 are all accessible through all these addressing modes. the register file is described in ?general purpose register file? on page 12 . 19 2513k?avr?07/09 atmega162/v figure 9. data memory map data memory access times this section describes the general access timi ng concepts for internal memory access. the internal data sram access is performed in two clk cpu cycles as described in figure 10 . figure 10. on-chip data sram access cycles eeprom data memory the atmega162 contains 512 by tes of data eeprom memory. it is organized as a separate data space, in which single by tes can be read and wr itten. the eeprom has an endurance of at least 100,000 write/erase cycles. the access between the eeprom and the cpu is described in the following, specif ying the eeprom address registers, the eeprom data register, and the eeprom control register. 32 registers 64 i/o registers internal sram (1024 x 8) 0x0000 - 0x001f 0x0020 - 0x005f 0x0460 0x045f 0xffff 0x0060 data memory external sram (0 - 64k x 8) memory configuration b 32 registers 64 i/o registers internal sram (1024 x 8) 0x0000 - 0x001f 0x0020 - 0x005f 0x04ff 0xffff 0x0060 - 0x00ff data memory external sram (0 - 64k x 8) memory configuration a 160 ext i/o reg. 0x0100 0x0500 clk wr rd data data address address valid t1 t2 t3 compute address read write cpu memory access instruction next instruction 20 2513k?avr?07/09 atmega162/v ?memory programming? on page 231 contains a detailed descri ption on eeprom programming in spi, jtag, or para llel programming mode. eeprom read/write access the eeprom access registers are accessible in the i/o space. the write access time for the eeprom is given in table 1 . a selftiming function, however, lets the user software detect when the next byte can be written. if the user code contains instructions that write the eeprom, some precau tions must be taken. in heavily filtered power supplies, v cc is likely to rise or fall slowly on power-up/down. this causes the device for some period of time to run at a voltage lower than specified as minimum for the clock frequency used. see ?prevent- ing eeprom corruption? on page 24 for details on how to avoid problems in these situations. in order to prevent unintentional eeprom writes, a specific write procedure must be followed. refer to the description of the eeprom control regist er for details on this. when the eeprom is read, the cpu is halted for fo ur clock cycles before the next in struction is executed. when the eeprom is written, the cp u is halted for two clock cycles before the next instruction is executed. the eeprom address register ? eearh and eearl ? bits 15..9 ? res: reserved bits these bits are reserved bits in the atmega162 and will always read as zero. ? bits 8..0 ? eear8..0: eeprom address the eeprom address registers ? eearh and eearl specify the eeprom address in the 512 bytes eeprom space. the eeprom data bytes are ad dressed linearly between 0 and 511. the initial value of eear is undefined. a proper value must be written before the eeprom may be accessed. bit 151413121110 9 8 ???????eear8eearh eear7 eear6 eear5 eear4 eear3 eear2 eear1 eear0 eearl 76543210 read/writerrrrrrrr/w r/w r/w r/w r/w r/w r/w r/w r/w initial value0000000x xxxxxxxx 21 2513k?avr?07/09 atmega162/v the eeprom data register ? eedr ? bits 7..0 ? eedr7.0: eeprom data for the eeprom write operation, the eedr register contains the data to be written to the eeprom in the address given by the eear regi ster. for the eeprom read operation, the eedr contains the data read out from the eeprom at the add ress given by eear. the eeprom control register ? eecr ? bits 7..4 ? res: reserved bits these bits are reserved bits in the atmega162 and will always read as zero. ? bit 3 ? eerie: eeprom ready interrupt enable writing eerie to one enables the eeprom ready interrupt if the i bit in sreg is set. writing eerie to zero disables the interrupt. the eeprom ready interrupt generates a constant inter- rupt when eewe is cleared. ? bit 2 ? eemwe: eeprom master write enable the eemwe bit determines whether setting eewe to one causes the eeprom to be written. when eemwe is set, setting eewe within four cl ock cycles will write data to the eeprom at the selected address. if eemwe is zero, sett ing eewe will have no effect. when eemwe has been written to one by software, hardware clears th e bit to zero after four clock cycles. see the description of the eewe bit for an eeprom write procedure. ? bit 1 ? eewe: eeprom write enable the eeprom write enable signal eewe is th e write strobe to the eeprom. when address and data are correctly set up, the eewe bit must be written to one to write the value into the eeprom. the eemwe bit must be written to one be fore a logical one is written to eewe, oth- erwise no eeprom write takes place. the following procedure should be followed when writing the eeprom (the order of steps 3 and 4 is not essential): 1. wait until eewe becomes zero. 2. wait until spmen in spmcr becomes zero. 3. write new eeprom address to eear (optional). 4. write new eeprom data to eedr (optional). 5. write a logical one to the eemwe bit while writing a zero to eewe in eecr. 6. within four clock cycles after setting eemwe, write a logical one to eewe. the eeprom can not be programmed during a cpu write to the flash memory. the software must check that the flash programming is co mpleted before initiating a new eeprom write. step 2 is only relevant if the software contai ns a boot loader allowing the cpu to program the flash. if the flash is never being updated by the cpu, step 2 can be omitted. see ?boot loader support ? read-while-write self-programming? on page 217 for details about boot programming. bit 76543210 msb lsb eedr read/write r/w r/w r/w r/w r/w r/w r/w r/w initial value00000000 bit 76543210 ? ? ? ? eerie eemwe eewe eere eecr read/write r r r r r/w r/w r/w r/w initial value 0 0 0 0 0 0 x 0 22 2513k?avr?07/09 atmega162/v caution: an interrupt between step 5 and step 6 will make the write cycle fail, since the eeprom master write enable will time-out. if an interrupt routine accessing the eeprom is interrupting another eeprom acce ss, the eear or eedr register will be modified, causing the interrupted eeprom access to fail. it is recommended to have the global interrupt flag cleared during all the steps to avoid these problems. when the write access time has elapsed, the eewe bit is cleared by hardware. the user soft- ware can poll this bit and wait for a zero before writing the next byte. when eewe has been set, the cpu is halted for two cycles before the next instruction is executed. ? bit 0 ? eere: eeprom read enable the eeprom read enable signal eere is the re ad strobe to the eeprom. when the correct address is set up in the eear register, the eere bit must be written to a logic one to trigger the eeprom read. the eeprom read access takes one instruction, and th e requested data is available immediately. when t he eeprom is read, the cpu is ha lted for four cycles before the next instruction is executed. the user should poll the eewe bit before starti ng the read operation. if a write operation is in progress, it is neither possi ble to read the eeprom, nor to change the eear register. the calibrated oscillator is used to time the eeprom accesses. table 1 lists the typical pro- gramming time for eeprom access from the cpu. note: 1. uses 1 mhz clock, independent of cksel fuse settings table 1. eeprom programming time symbol number of calibrated rc oscillator cycles (1) typ programming time eeprom write (from cpu) 8448 8.5 ms 23 2513k?avr?07/09 atmega162/v the following code examples show one assembly and one c function for writing to the eeprom. the examples assume that interrupts are controlled (e.g., by disabling interrupts globally) so that no in terrupts will occur during execution of these functions. the examples also assume that no flash boot loader is present in the software. if such code is present, the eeprom write function must also wait fo r any ongoing spm co mmand to finish. assembly code example eeprom_write: ; wait for completion of?previous write sbic eecr,eewe rjmp eeprom_write ; set up address (r18:r1?) in address register out eearh, r18 out eearl, r17 ; write data (r16) to da?a register out eedr,r16 ; write logical one to e?mwe sbi eecr,eemwe ; start eeprom write by ?etting eewe sbi eecr,eewe ret c code example void eeprom_write( unsigned int uiaddress, unsigned char ucdata) { /* wait for complet?on of previous write */ while(eecr & (1< 26 2513k?avr?07/09 atmega162/v external memory interface with all the features the external memory interf ace provides, it is well suited to operate as an interface to memory devices such as external sram and flash, and peripherals such as lcd- display, a/d, and d/a. the main features are: ? four different wait-state setti ngs (including no wait-state) ? independent wait-sta te setting for different external memo ry sectors (configurable sector size) ? the number of bits dedicated to address high byte is selectable ? bus keepers on data lines to minimize current consumption (optional) overview when the external memory (xmem) is enabl ed, address space outside the internal sram becomes available using the dedicated external memory pins (see figure 1 on page 2 , table 29 on page 70 , table 35 on page 75 , and table 41 on page 81 ). the memory configuration is shown in figure 11 . figure 11. external memory with sector select note: 1. address depends on the at mega161 compatibility fuse. see ?sram data memory? on page 18 and figure 9 on page 19 for details. using the external memory interface the interface consists of: ? ad7:0: multiplexed low-order address bus and data bus ? a15:8: high-order address bus (configurable number of bits) ? ale: address latch enable ?rd : read strobe. ?wr : write strobe. 0x0000 0x04ff/0x045f (1) external memory (0-64k x 8) 0xffff internal memory srl[2..0] srw11 srw10 srw01 srw00 lower sector upper sector 0x0500/0x0460 (1) 27 2513k?avr?07/09 atmega162/v the control bits for the external memory interface are located in three registers, the mcu con- trol register ? mcucr, the extended mcu co ntrol register ? emcucr, and the special function io register ? sfior. when the xmem interface is enabl ed, it will override the settings in the data direction registers corresponding to the ports dedicated to the interface. for details about this port override, see the alternate functions in section ?i/o-ports? on page 63 . the xmem interface will autodetect whether an access is inte rnal or external. if the access is external, the xmem interface will out- put address, data, and the control signals on the ports according to figure 13 (this figure shows the wave forms without wait-states). when ale goes from high to low, there is a valid address on ad7:0. ale is low during a data transfer. when the xmem interface is enabled, also an inter- nal access will cause activity on addr ess-, data- and ale ports, but the rd and wr strobes will not toggle during internal access. when the external memory interface is disabled, the normal pin and data direction settings are used. note that when the xmem interface is disabled, the address space above the internal sram boundary is not mapped into the internal sram. figure 12 illustrates how to connect an external sram to the avr using an octal latch (typically ?74x573? or equivalent) which is transparent when g is high. address latch requirements due to the high-speed operation of the xram interface, the address latch must be selected with care for system frequencies above 8 mhz @ 4v and 4 mhz @ 2.7v. when operating at condi- tions above these frequencies, the typical old style 74hc series latch becomes inadequate. the external memory interface is designed in comp liance to the 74ahc series latch. however, most latches can be used as long they comply with the main timing parameters. the main parameters for the address latch are: ? d to q propagation delay (t pd ). ? data setup time before g low (t su ). ? data (address) hold time after g low ( th ). the external memory interface is designed to guaranty minimum address hold time after g is asserted low of t h = 5 ns (refer to t laxx_ld /t llaxx_st in table 114 to table 121 on page 272 ). the d to q propagation delay (t pd ) must be taken into consideration when calculating the access time requirement of the external component. the data setup time before g low (t su ) must not exceed address valid to ale low (t avllc ) minus pcb wiring delay (dependent on the capacitive load). figure 12. external sram connected to the avr d[7:0] a[7:0] a[15:8] rd wr sram dq g ad7:0 ale a15:8 rd wr avr 28 2513k?avr?07/09 atmega162/v pull-up and bus keeper the pull-up resistors on the ad7:0 ports may be activated if the corresponding port register is written to one. to reduce power consumption in sleep mode, it is recommended to disable the pull-ups by writing the port register to zero before entering sleep. the xmem interface also provides a bus keeper on the ad7:0 lines. the bus keeper can be dis- abled and enabled in software as described in ?special function io register ? sfior? on page 32 . when enabled, the bus keeper will keep the previous value on the ad7:0 bus while these lines are tri-stated by the xmem interface. timing external memory devices have various timing requirements. to meet these requirements, the atmega162 xmem interface provides four different wait-states as shown in table 3 . it is impor- tant to consider the timing specification of the ex ternal memory device be fore selecting the wait- state. the most important parameters are the access time for the external memory in conjunc- tion with the set-up requirement of the atmega162. the access time for the external memory is defined to be the time from receiving the chip sele ct/address until the data of this address actu- ally is driven on the bus. the access time cannot exceed the time from the ale pulse is asserted low until data must be stable during a read sequence (t llrl + t rlrh - t dvrh in table 114 to table 121 on page 272 ). the different wait-states are set up in software. as an additional feature, it is possible to divide the external memory space in two sectors with individual wait-state settings. this makes it possible to connect two different memory devices with different timing require- ments to the same xmem interface. for xmem interface timing details, please refer to figure 118 to figure 121 , and table 114 to table 121 . note that the xmem interface is asynchronous and that the waveforms in the figures below are related to the internal system clock. the skew between the internal and external clock (xtal1) is not guaranteed (it varies between devices, temperature, and supply voltage). consequently, the xmem interface is not suited for synchronous operation. figure 13. external data memory cycles without wait-state (srwn1 = 0 and srwn0 =0) (1) note: 1. srwn1 = srw11 (upper sector) or srw01 (lower sector), srwn0 = srw10 (upper sector) or srw00 (lower sector). the ale pulse in period t4 is only present if the next instruction accesses the ram (internal or external). ale t1 t2 t3 write read wr t4 a15:8 address prev. addr. da7:0 address data prev. data xx rd da7:0 (xmbk = 0) data address data prev. data address da7:0 (xmbk = 1) system clock (clk cpu ) 29 2513k?avr?07/09 atmega162/v figure 14. external data memory cycles with srwn1 = 0 and srwn0 = 1 (1) note: 1. srwn1 = srw11 (upper sector) or srw01 (lower sector), srwn0 = srw10 (upper sector) or srw00 (lower sector) the ale pulse in period t5 is only present if the next instruction accesses the ram (internal or external). figure 15. external data memory cycles with srwn1 = 1 and srwn0 = 0 (1) note: 1. srwn1 = srw11 (upper sector) or srw01 (lower sector), srwn0 = srw10 (upper sector) or srw00 (lower sector). the ale pulse in period t6 is only present if the next instruction accesses the ram (internal or external). ale t1 t2 t3 write read wr t5 a15:8 address prev. addr. da7:0 address data prev. data xx rd da7:0 (xmbk = 0) data address data prev. data address da7:0 (xmbk = 1) system clock (clk cpu ) t4 ale t1 t2 t3 write read wr t6 a15:8 address prev. addr. da7:0 address data prev. data xx rd da7:0 (xmbk = 0) data address data prev. data address da7:0 (xmbk = 1) system clock (clk cpu ) t4 t5 30 2513k?avr?07/09 atmega162/v figure 16. external data memory cycles with srwn1 = 1 and srwn0 = 1 (1) note: 1. srwn1 = srw11 (upper sector) or srw01 (lower sector), srwn0 = srw10 (upper sector) or srw00 (lower sector). the ale pulse in period t7 is only present if the next instruction accesses the ram (internal or external). xmem register description mcu control register ? mcucr ? bit 7 ? sre: external sram/xmem enable writing sre to one enables the external memory interface.the pin functions ad7:0, a15:8, ale, wr , and rd are activated as the alternate pin functions. the sre bit overrides any pin direction settings in the respective data direction registers. writing sre to zero, disables the external memory interface and the normal pin and data direction settings are used. ? bit 6 ? srw10: wait state select bit for a detailed description, see common descr iption for the srwn bits below (emcucr description). extended mcu control register ? emcucr ? bit 6..4 ? srl2, srl1, srl0 : wait state sector limit it is possible to configure different wait-state s for different external memory addresses. the external memory address space can be divided in two sectors that have separate wait-state bits. the srl2, srl1, and srl0 bits select the splitting of these sectors, see table 2 and figure 11 . by default, the srl2, srl1, and srl0 bits are set to zero and the entire external memory address space is treated as one sector. when the entire sram address space is configured as one sector, the wait-states are configured by the srw11 and srw10 bits. ale t1 t2 t3 write read wr t7 a15:8 address prev. addr. da7:0 address data prev. data xx rd da7:0 (xmbk = 0) data address data prev. data address da7:0 (xmbk = 1) system clock (clk cpu ) t4 t5 t6 bit 76543210 sre srw10 se sm1 isc11 isc10 isc01 isc00 mcucr read/write r/w r/w r/w r/w r/w r/w r/w r/w initial value00000000 bit 76543210 sm0 srl2 srl1 srl0 srw01 srw00 srw11 isc2 emcucr read/write r/w r/w r/w r/w r/w r/w r/w r/w initial value00000000 31 2513k?avr?07/09 atmega162/v ? bit 1 and bit 6 mcucr ? srw11, srw10: wait-state select bits for upper sector the srw11 and srw10 bits control the number of wait-states for the upper sector of the exter- nal memory address space, see table 3 . ? bit 3..2 ? srw01, srw00: wait-state select bits for lower sector the srw01 and srw00 bits control the number of wait-states for the lower sector of the exter- nal memory address space, see table 3 . note: 1. n = 0 or 1 (lower/upper sector). for further details of the timing and wait-states of the external memory interface, see figure 13 to figure 16 how the setting of the srw bits affects the timing. table 2. sector limits with different settings of srl2..0 srl2 srl1 srl0 sector limits 000 lower sector = n/a upper sector = 0x1100 - 0xffff 001 lower sector = 0x1100 - 0x1fff upper sector = 0x2000 - 0xffff 010 lower sector = 0x1100 - 0x3fff upper sector = 0x4000 - 0xffff 011 lower sector = 0x1100 - 0x5fff upper sector = 0x6000 - 0xffff 100 lower sector = 0x1100 - 0x7fff upper sector = 0x8000 - 0xffff 101 lower sector = 0x1100 - 0x9fff upper sector = 0xa000 - 0xffff 110 lower sector = 0x1100 - 0xbfff upper sector = 0xc000 - 0xffff 111 lower sector = 0x1100 - 0xdfff upper sector = 0xe000 - 0xffff table 3. wait-states (1) srwn1 srwn0 wait-states 0 0 no wait-states 0 1 wait one cycle during read/write strobe 1 0 wait two cycles duri ng read/write strobe 11 wait two cycles during read/write and wait one cycle before driving out new address 32 2513k?avr?07/09 atmega162/v special function io register ? sfior ? bit 6 ? xmbk: external memory bus keeper enable writing xmbk to one enables the bus keeper on the ad7:0 lines. when the bus keeper is enabled, ad7:0 will keep the last driven value on the lines even if the xmem interface has tri- stated the lines. writing xmbk to zero disables the bus keeper. xmbk is not qualified with sre, so even if the xmem in terface is disabled, the bus keepers are still activated as long as xmbk is one. ? bit 6..3 ? xmm2, xmm1, xmm0: external memory high mask when the external memory is enabled, all port c pins are used for the high address byte by default. if the full 60kb address space is not requi red to access the external memory, some, or all, port c pins can be released for normal port pin function as described in table 4 . as described in ?using all 64kb locations of external memory? on page 34 , it is possible to use the xmmn bits to access all 64kb locations of the external memory. using all locations of external memory smaller than 64 kb since the external memory is mapped after the internal memory as shown in figure 11 , the external memory is not addressed when addressing the first 1,280 bytes of data space. it may appear that the first 1,280 bytes of the external memory are inaccessible (external memory addresses 0x0000 to 0x04ff). however, when connecting an external memory smaller than 64 kb, for example 32 kb, these locations are easily accessed simply by addressing from address 0x8000 to 0x84ff. since the external memory ad dress bit a15 is not connected to the external memory, addresses 0x8000 to 0x84 ff will appear as addresses 0x0000 to 0x04ff for the exter- nal memory. addressing above address 0x84ff is not recommende d, since this will address an external memory location that is already accessed by another (lower) address. to the applica- tion software, the external 32 kb memory will appear as one linear 32 kb address space from 0x0500 to 0x84ff. th is is illustrated in figure 17 . memory configuration b refers to the atmega161 compatibility mode , configuration a to th e non-compatible mode. bit 7654321 0 tsm xmbk xmm2 xmm1 xmm0 pud psr2 psr310 sfior read/write r/w r/w r/w r/w r/w r/w r/w r/w initial value 0 0 0 0 0 0 0 0 table 4. port c pins released as normal port pins when the external memory is enabled xmm2 xmm1 xmm0 # bits for external memory address released port pins 0008 (full 60 kb space) none 0017 pc7 0106 pc7 - pc6 0115 pc7 - pc5 1004 pc7 - pc4 1013 pc7 - pc3 1102 pc7 - pc2 111no address high bits full port c 33 2513k?avr?07/09 atmega162/v when the device is set in at mega161 compatib ility mode, the internal address space is 1,120 bytes. this implies that the first 1,120 byte s of the external memory can be accessed at addresses 0x8000 to 0x 845f. to the application software, the external 32 kb memory will appear as one linear 32 kb address space from 0x0460 to 0x845f. figure 17. address map with 32 kb external memory 0x0000 0x04ff 0xffff 0x0500 0x7fff 0x8000 0x84ff 0x8500 0x0000 0x04ff 0x0500 0x7fff memory configuration a memory configuration b internal memory (unused) avr memory map external 32k sram external memory 0x0000 0x045f 0xffff 0x0460 0x7fff 0x8000 0x845f 0x8460 0x0000 0x045f 0x0460 0x7fff internal memory (unused) avr memory map external 32k sram external memory 34 2513k?avr?07/09 atmega162/v using all 64kb locations of external memory since the external memory is mapped after the internal memory as shown in figure 11 , only 64,256 bytes of external memory are availabl e by default (address space 0x0000 to 0x04ff is reserved for internal memory). however, it is possible to take advantage of the entire external memory by masking the higher address bits to zero. this can be done by using the xmmn bits and control by software the most significant bits of the address. by setting port c to output 0x00, and releasing the most si gnificant bits for normal port pin operation, the memory interface will address 0x0000 - 0x1fff. see code example below. note: 1. the example code assumes that the pa rt specific header file is included. care must be exercised using this option as most of the memory is masked away. assembly code example (1) ; offset is defined to 0?2000 to ensure ; external memory access ; configure port c (addr?ss high byte) to ; output 0x00 when the p?ns are released ; for normal port pin op?ration ldi r16, 0xff out ddrc, r16 ldi r16, 0x00 out portc, r16 ; release pc7:5 ldi r16, (1< 36 2513k?avr?07/09 atmega162/v clock sources the device has the following clock source options, selectable by flash fuse bits as shown below. the clock from the selected source is input to the avr clock generator, and routed to the appropriate modules. note: for all fuses ?1? means unprogrammed while ?0? means programmed. the various choices for each clocking option is given in the following sections. when the cpu wakes up from power-down or power-save, the selected clock source is used to time the start- up, ensuring stable osc illator operation bef ore instruction execution st arts. when the cpu starts from reset, there is an additional delay allowing the power to reach a stable level before com- mencing normal operation. the watchdog oscillator is used for timing this realtime part of the start-up time. the number of wdt oscillator cycl es used for each time-out is shown in table 6 . the frequency of t he watchdog oscillator is volt age dependent as shown in ?atmega162 typi- cal characteristics? on page 275 . default clock source the device is shipped with cksel = ?0010?, sut = ?10? and ck div8 programmed. the default clock source setting is therefore the internal rc oscillato r with longest startup time and an initial system clock prescaling of 8. this default setti ng ensures that all users can make their desired clock source setting using an in-system or parallel programmer. crystal oscillator xtal1 and xtal2 are input and output, respectively, of an inverting amplifier which can be con- figured for use as an on-chip oscillator, as shown in figure 19 . either a quartz crystal or a ceramic resonator may be used. c1 and c2 should always be equal for both crystals and resonators. the optimal value of the capacitors depends on the crystal or resonator in use, the amount of stray capacitance, and the electromagnetic noise of the environment. some initial guidelines for choosing capacitors for use with crystals are given in table 7 . for ceramic resonators, the capacitor values given by the manufacturer should be used. table 5. device clocking options select device clocking option cksel3..0 external crystal/ceramic resonator 1111 - 1000 external low-frequency crystal 0111 - 0100 calibrated internal rc oscillator 0010 external clock 0000 reserved 0011, 0001 table 6. number of watchdog oscillator cycles typ time-out (v cc = 5.0v) typ time-out (v cc = 3.0v) number of cycles 4.1 ms 4.3 ms 4k (4,096) 65 ms 69 ms 64k (65,536) 37 2513k?avr?07/09 atmega162/v figure 19. crystal oscillator connections the oscillator can operat e in four different mo des, each optimized for a specific frequency range. the op erating mode is selected by t he fuses cksel3:1 as shown in table 7 . note: 1. this option should not be used with crystals, only with ceramic resonators. the cksel0 fuse together with the sut1..0 fuses select the start-up times as shown in table 8 . table 7. crystal oscillator operating modes cksel3:1 frequency range (mhz) recommended range for capacitors c1 and c2 for use with crystals (pf) 100 (1) 0.4 - 0.9 ? 101 0.9 - 3.0 12 - 22 110 3.0 - 8.0 12 - 22 111 8.0 - 12 - 22 table 8. start-up times for the crystal oscillator clock selection cksel0 sut1:0 start-up time from power-down and power-save additional delay from reset (v cc = 5.0v) recommended usage 0 00 258 ck (1) 4.1 ms ceramic resonator, fast rising power 0 01 258 ck (1) 65 ms ceramic resonator, slowly rising power 010 1k ck (2) ? ceramic resonator, bod enabled 011 1k ck (2) 4.1 ms ceramic resonator, fast rising power 100 1k ck (2) 65 ms ceramic resonator, slowly rising power 1 01 16k ck ? crystal oscillator, bod enabled 1 10 16k ck 4.1 ms crystal oscillator, fast rising power 1 11 16k ck 65 ms crystal oscillator, slowly rising power xtal2 xtal1 gnd c2 c1 38 2513k?avr?07/09 atmega162/v notes: 1. these options should only be used when not operating close to the maximum frequency of the device, and only if frequency stability at start- up is not important for the application. these options are not suitable for crystals. 2. these options are intended for use with ceramic resonators and will ensure frequency stability at start-up. they can also be used with cryst als when not operating close to the maximum fre- quency of the device, and if frequency stability at start-up is not important for the application. low-frequency crystal oscillator to use a 32.768 khz watch crystal as the clock source for the device, the low-frequency crystal oscillator must be select ed by setting the cksel fuses to ? 0100?, ?0101?, ?0110? or ?0111?. the crystal should be connected as shown in figure 19 . if cksel equals ?0110? or ?0111?, the inter- nal capacitors on xtal1 and xtal2 are enabled, thereby removing the need for external capacitors. the internal capacitors have a nominal value of 10 pf. when this oscillator is selected, start-up times are determined by the sut fuses (real time-out from reset) and cksel0 (number of clock cycles) as shown in table 9 and table 10 . note: 1. these options should only be used if frequen cy stability at start-up is not important for the application. calibrated internal rc oscillator the calibrated internal rc oscillator provides a fixed 8.0 mhz clock. the frequency is nominal value at 3v and 25 c. if 8.0 mhz frequency exceed the specification of the device (depends on v cc ), the ckdiv8 fuse must be programmed in order to divide the internal frequency by 8 dur- ing start-up. see ?system clock pre scaler? on page 41 for more details. this clock may be selected as the system clock by prog ramming the cksel fuses as shown in table 11 . if selected, it will operate with no ex ternal components. du ring reset, hardware loads the calibra- tion byte into the osccal regi ster and thereby automatically calibrates the rc oscillator. at 3v and 25 c, this calibration gives a frequency within 10% of the nominal frequency. using cal- ibration methods as described in application note s available at www.atmel.com/avr it is possible to achieve 2% accuracy at any given v cc and temperatur e. when this oscillator is used as the chip clock, the watchdog oscillator will still be used for the watchdog ti mer and for the reset table 9. start-up delay from reset when low-fr equency crystal osc illator is selected sut1:0 additional delay from reset (v cc = 5.0v) recommended usage 00 0 ms fast rising power or bod enabled 01 4.1 ms fast rising power or bod enabled 10 65 ms slowly rising power 11 reserved table 10. start-up times for the low-frequency crystal o scillator clock selection cksel1:0 internal capacitors enabled? start-up time from power-down and power-save recommended usage 00 (1) no 1k ck 01 no 32k ck stable frequency at start-up 10 (1) ye s 1 k c k 11 yes 32k ck stable frequency at start-up 39 2513k?avr?07/09 atmega162/v time-out. for more information on the pre-programmed calibration value, see the section ?cali- bration byte? on page 234 . note: 1. the device is shipped with this option selected. when this oscillator is select ed, start-up times are determined by the sut fuses as shown in table 12 . xtal1 and xtal2 should be left unconnected (nc). note: 1. the device is shipped with this option selected. oscillator calibration register ? osccal ? bit 7 ? res: reserved bit this bit is reserved bit in the atmega162, and will always read as zero. ? bits 6..0 ? cal6..0: oscillator calibration value writing the calibration byte to th is address will trim the internal os cillator to remove process vari- ations from the oscillator frequency. this is done automatically during chip reset. when osccal is zero, the lowest available frequency is chosen. writing non-zero values to this regis- ter will increase the frequency of the internal oscillator. writing 0x7f to the register gives the highest available freque ncy. the calibrated oscillator is used to time eeprom and flash access. if eeprom or flash is written, do not ca librate to more than 10 % above the nominal fre- quency. otherwise, the eeprom or flash write may fail. table 11. internal calibrated rc os cillator oper ating modes cksel3:0 nominal frequency 0010 (1) 8.0 mhz table 12. start-up times for the in ternal calibrated rc os cillator clock selection sut1:0 start-up time from power- down and power-save additional delay from reset (v cc = 5.0v) recommended usage 00 6 ck ? bod enabled 01 6 ck 4.1 ms fast rising power 10 (1) 6 ck 65 ms slowly rising power 11 reserved bit 76543210 ? cal6 cal5 cal4 cal3 cal2 cal1 cal0 osccal read/write r r/w r/w r/w r/w r/w r/w r/w initial value 0 device specific calibration value 40 2513k?avr?07/09 atmega162/v external clock to drive the device from an external clock source, xtal1 should be driven as shown in figure 20 . to run the device on an external clock, th e cksel fuses must be programmed to ?0000?. figure 20. external clock drive configuration when this clock source is sele cted, start-up times are determined by the sut fuses as shown in table 14 . when applying an external clock, it is required to avoid sudden changes in the applied clock fre- quency to ensure stable operation of the mcu. a variation in frequency of more than 2% from one clock cycle to the next can lead to unpredictable behavior. it is required to en sure that the mcu is kept in reset during such changes in the clock frequency. note that the system clock prescaler can be used to implement run-time changes of the internal clock frequency while still ensuri ng stable operation. refer to ?system clock prescaler? on page 41 for details. clock output buffer when the ckout fuse is progra mmed, the system clock will be ou tput on portb 0. this mode is suitable when chip clock is used to drive other circuits on the system. the clock will be output also during reset and the normal operation of portb will be overridden when t he fuse is pro- table 13. internal rc oscillator frequency range. osccal value min frequency in percentage of nominal frequency max frequency in percentage of nominal frequency 0x00 50% 100% 0x3f 75% 150% 0x7f 100% 200% table 14. start-up times for the external clock selection sut1..0 start-up time from power-down and power-save additional delay from reset (v cc = 5.0v) recommended usage 00 6 ck ? bod enabled 01 6 ck 4.1 ms fast rising power 10 6 ck 65 ms slowly rising power 11 reserved external clock signal 41 2513k?avr?07/09 atmega162/v grammed. any clock sources, incl uding internal rc oscillator, can be selected when portb 0 serves as clock output. if the system clock prescaler is used, it is t he divided system clock that is output when the ckout fuse is programmed. see ?system clock prescaler? on page 41. for a description of the system clock prescaler. timer/counter oscillator for avr microcontrollers with timer/counter osc illator pins (tosc1 and tosc2), the crystal is connected directly betw een the pins. the oscilla tor provides internal capacitors on tosc1 and tosc2, thereby removing the need for external ca pacitors. the internal capacitors have a nom- inal value of 10 pf. the oscilla tor is optimized for use with a 32.768 khz watch crystal. applying an external clock source to tosc1 is not recommended. system clock prescaler the atmega162 system clock can be divided by setting the clock prescale register ? clkpr. this feature can be used to decrease the system clock frequency and power consumption when the requirement for processing power is low. this can be used with all clock source options, and it will affect the clock frequency of the cpu and all synchronous peripherals. clk i/o , clk cpu , and clk flash are divided by a factor as shown in table 15 . note that the clock frequency of clk asy (asynchronously timer/counter) only will be scaled if the timer/counter is clocked synchronously. when switching between prescaler settings, the system clock prescaler ensures that no glitches occur in the clock system and that no intermediate frequency is higher than neither the clock frequency corresponding to the previous setting, nor the clock frequency corresponding to the new setting. the ripple counter that implements the prescaler runs at the frequency of the undivided clock, which may be faster than the cpu?s clock frequency. hence, it is not possible to determine the state of the prescaler ? even if it were readable, and the exact time it takes to switch from one clock division to another cannot be exactly predicted. from the time the clkps values ar e written, it takes between t1 + t2 and t1 + 2*t2 before the new clock frequency is active. in this interval, 2 active clock edges are produced. here, t1 is the previous clock period, and t2 is the period corresponding to the new prescaler setting. to avoid unintentional changes of clock frequency, a special write procedure must be followed to change the clkps bits: 1. write the clock prescaler change enable (clkpce) bit to one and all other bits in clkpr to zero. 2. within four cycles, write the desired value to clkps while writing a zero to clkpce. caution: an interrupt between step 1 and step 2 w ill make the timed sequence fail. it is recom- mended to have the global interrupt flag cleared during these steps to avoid this problem. clock prescale register ? clkpr ? bit 7 ? clkpce: clock prescaler change enable the clkpce bit must be written to logic one to enable change of the clkps bits. clkpce is cleared by hardware four cycles after it is writ ten or when clkps is written. setting the clkpce bit will disable interrupts, as explai ned in the clkps description below. bit 7 6 5 4 3 2 1 0 clkpce ? ? ? clkps3 clkps2 clkps1 clkps0 clkpr read/write r/w r r r r/w r/w r/w r/w initial value 0 0 0 0 see bit description 42 2513k?avr?07/09 atmega162/v ? bits 3..0 ? clkps3..0: clock prescaler select bits 3 - 0 these bits define the division factor between the selected clock source and the internal system clock. these bits can be written run-time to vary the clock frequency to suit the application requirements. as the divider divides the master clock input to the mcu, the speed of all synchro- nous peripherals is reduced when a division fact or is used. the division factors are given in table 15 . the ckdiv8 fuse determines the initial value of the clkps bits. if ckdiv8 is unprogrammed, the clkps bits will be reset to ?0000?. if ckdiv8 is programmed, clkps bits are reset to ?0011?, giving a division factor of 8 at start up. this feature should be used if the selected clock source has a higher frequency than the maximum frequency of the device at the present operat- ing conditions. note that any value can be written to the clkps bits regardless of the ckdiv8 fuse setting. the application software must ensure that a sufficient division factor is chosen if the selected clock source has a higher frequency than the maximum frequency of the device at the present operating conditions. the device is shipped with the ckdiv8 fuse programmed. table 15. clock prescaler select clkps3 clkps2 clkps1 clkps0 clock division factor 00001 00012 00104 00118 010016 010132 011064 0111128 1000256 1001reserved 1010reserved 1011reserved 1100reserved 1101reserved 1110reserved 1111reserved 43 2513k?avr?07/09 atmega162/v power management and sleep modes sleep modes enable the application to shut down unused modules in the mcu, thereby saving power. the avr provides various sleep modes allowing the user to tailor the power consump- tion to the application?s requirements. to enter any of the five sleep modes, the se bit in mcucr must be wri tten to logic one and a sleep instruction must be execut ed. the sm2 bit in mcucsr, th e sm1 bit in mcucr, and the sm0 bit in the emcucr register select which sleep mode (idle, power-down, power-save, standby, or extended standby) will be ac tivated by the sleep instruction. see table 16 for a summary. if an enabled interrupt occurs while the mcu is in a sleep mode, the mcu wakes up. the mcu is then halted for four cycles in addition to the start-up time, executes the interrupt rou- tine, and resumes execution from the instruction following sleep. the contents of the register file and sram are unaltered when the device wakes up from sleep. if a reset occurs during sleep mode, the mcu wakes up and executes from the reset vector. figure 18 on page 35 presents the different clock systems in the atmega162, and their distribu- tion. the figure is helpful in selecting an appropriate sleep mode. mcu control register ? mcucr ? bit 5 ? se: sleep enable the se bit must be written to logic one to make the mcu enter the sleep mode when the sleep instruction is executed. to avoid the mcu enteri ng the sleep mode unless it is the programmer?s purpose, it is recommended to write the sleep enable (se) bit to one just before the execution of the sleep instruction and to clear it immediately af ter waking up. ? bit 4 ? sm1: sleep mode select bit 1 the sleep mode select bits select between t he five available sleep modes as shown in table 16 . mcu control and status register ? mcucsr ? bit 5 ? sm2: sleep mode select bit 2 the sleep mode select bits select between t he five available sleep modes as shown in table 16 . bit 76543210 sre srw10 se sm1 isc11 isc10 isc01 isc00 mcucr read/write r/w r/w r/w r/w r/w r/w r/w r/w initial value00000000 bit 76543210 jtd ?sm2 jtrf wdrf borf extrf porf mcucsr read/write r/w r/w r/w r/w r/w r/w r/w r/w initial value00000000 44 2513k?avr?07/09 atmega162/v extended mcu control register ? emcucr ? bit 7 ? sm0: sleep mode select bit 0 the sleep mode select bits select between t he five available sleep modes as shown in table 16 . note: 1. standby mode and extended standby mode are only available with external crystals or resonators. idle mode when the sm2..0 bits are written to 000, the sleep instruction makes the mcu enter idle mode, stopping the cpu but allowing the spi, usart, analog comparator, timer/counters, watchdog, and the interrupt system to continue operating. this sleep mode basically halts clk cpu and clk flash , while allowing the other clocks to run. idle mode enables the mcu to wake up from external triggered interrupts as well as internal ones like the timer overflow and usart transmit complete interrupts. if wake-up from the analog comparator interrupt is not required, the analog comparator can be powered down by setting the acd bit in the analog comparator control and status regist er ? acsr. this will reduce power consumption in idle mode. power-down mode when the sm2..0 bits are written to 010, the sleep instruction makes the mcu enter power- down mode. in this mode , the external oscillator is stopped, while the exte rnal interrup ts and the watchdog continue operating (if enabled). only an external reset, a watchdog reset, a brown- out reset, an external level interrupt on int0 or int1, an external interrupt on int2, or a pin change interrupt can wake up the mcu. this sleep mode basically halts all generated clocks, allowing operation of asynchronous modules only. note that if a level triggered interrupt is used for wake-up from power-down mode, the changed level must be held for some time to wake up the mcu. refer to ?external interrupts? on page 84 for details. when waking up from power-down mode, there is a delay from the wake-up condition occurs until the wake-up becomes effective. this allows the clock to restart and become stable after having been stopped. the wake-up period is defined by the same cksel fuses that define the reset time-out period, as described in ?clock sources? on page 36 . bit 76543210 sm0 srl2 srl1 srl0 srw01 srw00 srw11 isc2 emcucr read/write r/w r/w r/w r/w r/w r/w r/w r/w initial value00000000 table 16. sleep mode select sm2 sm1 sm0 sleep mode 000idle 001reserved 010power-down 011power-save 100reserved 101reserved 110standby (1) 1 1 1 extended standby (1) 45 2513k?avr?07/09 atmega162/v power-save mode when the sm2..0 bits are written to 011, the sleep instruction makes the mcu enter power- save mode. this mode is identical to power-down, with one exception: if timer/counter2 is clocked as ynchronously, i.e., the as2 bit in assr is set, timer/counter2 will run during sleep. the device can wake up from either timer overflow or output compare event from timer/counter2 if the corresponding timer/counter2 interrupt enable bits are set in timsk, and the global interrupt enable bit in sreg is set. if the asynchronous timer is not clocked asynchronously, power-down mode is recommended instead of power-save mode because the contents of the registers in the asynchronous timer should be considered undefined after wake-up in power-save mode if as2 is 0. this sleep mode basically halts all clocks except clk asy , allowing operation only of asynchronous modules, including timer/counter 2 if clocked asynchronously. standby mode when the sm2..0 bits are 110 and an external crystal/resonator clock option is selected, the sleep instruction makes the mcu enter standby mode. this mode is identical to power-down with the exception that the main oscillator is kept running. from standby mode, the device wakes up in six clock cycles. extended standby mode when the sm2..0 bits are 111 and an external crystal/resonator clock option is selected, the sleep instruction makes the m cu enter extended standby mode . this mode is identical to power-save mode with the exception that the main oscillator is kept running. from extended standby mode, the device wa kes up in six clock cycles. notes: 1. external crystal or re sonator selected as clock source 2. if as 2 bit in assr is set 3. for int1 and int0, only level interrupt table 17. active clock domains and wake up sources in the different sleep modes active clock domains oscillators wake-up sources sleep mode clk cpu clk flash clk io clk asy main clock source enabled timer osc enabled int2 int1 int0 and pin change timer 2 spm/ eeprom ready other i/o idle x x x x (2) xxxx power-down x (3) power-save x (2) x (2) x (3) x (2) standby (1) xx (3) extended standby (1) x (2) xx (2) x (3) x (2) 46 2513k?avr?07/09 atmega162/v minimizing power consumption there are several issues to consider when trying to minimize the power consumption in an avr controlled system. in general, sleep modes should be used as much as possible, and the sleep mode should be selected so that as few as possi ble of the device?s functions are operating. all functions not needed should be disabled. in particular, the following modules may need special consideration when trying to achieve th e lowest possible power consumption. analog comparator when entering idle mode, the analog comparator should be disabled if not needed. in the other sleep modes, the analog comparator is automatically disabled. however, if the analog compar- ator is set up to use the internal voltage reference as input, the analog comparator should be disabled in all sleep modes. otherwise, the internal voltage reference will be enabled, indepen- dent of sleep mode. refer to ?analog comparator? on page 195 for details on how to configure the analog comparator. brown-out detector if the brown-out detector is not needed in the application, this module should be turned off. if the brown-out detector is enabled by the bodlevel fuses, it will be enabled in all sleep modes, and hence, always consume power. in the deeper sleep modes, this will contribute significantly to the total current consumption. refer to ?brown-out detection? on page 50 for details on how to configure the brown-out detector. internal voltage reference the internal voltage reference will be enabled when needed by the brown-out detector or the analog comparator. if these modules are disabled as described in the sections above, the inter- nal voltage reference will be disabled and it will not be consuming power. when turned on again, the user must allow the reference to start up before the output is used. if the reference is kept on in sleep mode, the output can be used immediately. refer to ?internal voltage reference? on page 52 for details on the start-up time. watchdog timer if the watchdog timer is not needed in the application, this module should be turned off. if the watchdog timer is enabled, it will be enabled in all sleep modes, and hence, always consume power. in the deeper slee p modes, this will contribute signific antly to the total current consump- tion. refer to ?watchdog timer? on page 52 for details on how to configure the watchdog timer. port pins when entering a sleep mode, all port pins should be configured to use minimum power. the most important thing is to ensure that no pins drive resistive loads. in sleep modes where the i/o clock (clk i/o ) is stopped, the input buffers of the devic e will be disabled. this ensures that no power is consumed by the input logic when not ne eded. in some cases, the input logic is needed for detecting wake-up conditions, and it will then be enabled. refer to the section ?digital input enable and sleep modes? on page 67 for details on which pins are enabled. if the input buffer is enabled and the input signal is left floati ng or have an analog signal level close to v cc /2, the input buffer will use excessive power. jtag interface and on-chip debug system if the on-chip debug system is enabled by the ocden fuse and the chip enter power down or power save sleep mode, the main clock source remains enabled. in these sl eep modes, this will contribute significantly to the total current c onsumption. there are three alternative ways to avoid this: ? disable ocden fuse. ? disable jtagen fuse. ? write one to the jtd bit in mcucsr. the tdo pin is left floating when the jtag interf ace is enabled while th e jtag tap controller is not shifting data. if the hardware connected to t he tdo pin does not pull up the logic level, power consumption will increase. note that the tdi pin fo r the next device in the scan chain con- tains a pull-up that avoids this problem. writi ng the jtd bit in the mcucsr register to one or leaving the jtag fuse unprogrammed disables the jtag interface. 47 2513k?avr?07/09 atmega162/v system control and reset resetting the avr during reset, all i/o registers are set to their in itial values, and the program starts execution from the reset vector. the instruction placed at the reset vector must be a jmp ? absolute jump ? instruction to the reset handling routine. if the program never enables an interrupt source, the interrupt vectors are not used, and regular program code can be placed at these locations. this is also the case if the reset vector is in the app lication section while the interrupt vectors are in the boot section or vice versa. the circuit diagram in figure 21 shows the reset logic. table 18 defines the electrical parameters of the reset circuitry. the i/o ports of the avr are immediately reset to their initial state when a reset source goes active. this does not require any clock source to be running. after all reset sources have gone inactive, a delay counter is invoked, stretching the internal reset. this allows the power to reach a stable level before normal operation starts. the time- out period of the delay counter is defined by t he user through the cksel fuses. the different selections for the delay period are presented in ?clock sources? on page 36 . reset sources the atmega162 has five sources of reset: ? power-on reset. the mcu is reset when the supply voltage is be low the power-on reset threshold (v pot ). ? external reset. the mcu is reset wh en a low level is present on the reset pin for longer than the minimum pulse length. ? watchdog reset. the mcu is reset when the watchdog timer period expires and the watchdog is enabled. ? brown-out reset. the mcu is reset when the supply voltage v cc is below the brown-out reset threshold (v bot ) and the brown-out detector is enabled. the device is guaranteed to operate at maximum frequency for the v cc voltage down to v bot . v bot must be set to the corresponding minimum voltage of the device (i.e., minimum v bot for atmega162v is 1.8v). ? jtag avr reset. the mcu is reset as long as there is a logic one in the reset register, one of the scan chains of the jtag system. refer to the section ?ieee 1149.1 (jtag) boundary-scan? on page 204 for details. 48 2513k?avr?07/09 atmega162/v figure 21. reset logic note: 1. the power-on reset will not work unless the supply voltage has been below v pot (falling) power-on reset a power-on reset (por) pulse is generated by an on-chip detection circuit. the detection level is defined in table 18 . the por is activated whenever v cc is below the detection level. the por circuit can be used to trigger the start-up re set, as well as to detect a failure in supply voltage. a power-on reset (por) circuit ensures that th e device is reset from power-on. reaching the power-on reset threshold voltage invokes the delay counter, which determines how long the device is kept in reset after v cc rise. the reset signal is acti vated again, without any delay, when v cc decreases below the detection level. table 18. reset characteristics symbol parameter condition min. typ. max. units v pot power-on reset threshold voltage (rising) t a = -40 - 85 c0.7 1.0 1.4 v power-on reset threshold voltage (falling) (1) t a = -40 - 85 c0.6 0.9 1.3 v v rst reset pin threshold voltage v cc = 3v 0.1 v cc 0.9 v cc v t rst minimum pulse width on reset pin v cc = 3v 2.5 s mcu control and status register (mcucsr) bodlevel [ 2..0] delay counters cksel[3:0] ck timeout wdrf borf extrf porf data b u s clock generator spike filter pull-up resistor jtrf jtag reset register watchdog oscillator sut[1:0] watchdog timer v cc reset reset circuit brown-out reset circuit power-on reset circuit counter reset internal reset 49 2513k?avr?07/09 atmega162/v figure 22. mcu start-up, reset tied to v cc . figure 23. mcu start-up, reset extended externally external reset an external reset is generated by a low level on the reset pin. reset pulses longer than the minimum pulse width (see table 18 ) will generate a reset, even if the clock is not running. shorter pulses are not guaranteed to generate a reset. when the applied signal reaches the reset threshold voltage ? v rst on its positive edge, the delay counter starts the mcu after the time-out period t tout has expired. figure 24. external reset during operation v reset time-out internal reset t tout v pot v rst cc reset time-out internal reset t tout v pot v rst v cc cc 50 2513k?avr?07/09 atmega162/v brown-out detection atmega162 has an on-chip brown-out detect ion (bod) circuit for monitoring the v cc level dur- ing operation by comparing it to a fixed trig ger level. the trigger level for the bod can be selected by the bodlevel fuses. the trigger level has a hysteresis to ensure spike free brown-out detection. the hysteresis on the detection level should be interpreted as v bot+ = v bot + v hyst /2 and v bot- = v bot - v hyst /2. notes: 1. v bot may be below nominal minimum operating voltage for some devices. for devices where this is the case, the devi ce is tested down to v cc = v bot during the production test. this guar- antees that a brown-out reset will occur before v cc drops to a voltage where correct operation of the microcontroller is no long er guaranteed. this test is performed using bodlevel = 110 for atmega162v, bodl evel = 101 and bodlevel = 100 for atmega162. 2. for atmega162v. otherwise reserved. when the bod is enabled and v cc decreases to a value below the trigger level (v bot- in figure 25 ), the brown-out reset is immediately activated. when v cc increases above the trigger level (v bot+ in figure 25 ), the delay counter starts the mcu after the time-out period t tout has expired. the bod circuit will only detect a drop in v cc if the voltage stays below the trigger level for lon- ger than t bod given in table 18 . table 19. bodlevel fuse coding bodlevel fuses [2:0] min. v bot (1) typ. v bot max. v bot units 111 bod disabled 110 (2) 1.7 1.8 2.0 v 101 2.5 2.7 2.9 100 4.1 4.3 4.5 011 (2) 2.1 2.3 2.5 010 reserved 001 000 table 20. brown-out hysteresis symbol parameter min. typ. max. units v hyst brown-out detector hysteresis 50 mv t bod min pulse width on brown-out reset 2 s 51 2513k?avr?07/09 atmega162/v figure 25. brown-out reset during operation watchdog reset when the watchdog times out, it will generate a short reset pulse of one ck cycle duration. on the falling edge of this pulse, the delay timer starts counting the time-out period t tout . refer to page 52 for details on operation of the watchdog timer. figure 26. watchdog reset during operation mcu control and status register ? mcucsr the mcu control and status register provides information on which reset source caused an mcu reset. ? bit 4 ? jtrf: jtag reset flag this bit is set if a reset is being caused by a logic one in the jtag reset register selected by the jtag instruction avr_reset. this bit is rese t by a power-on reset, or by writing a logic zero to the flag. ? bit 3 ? wdrf: watchdog reset flag this bit is set if a watchdog re set occurs. the bit is reset by a power-on reset, or by writing a logic zero to the flag. v cc reset time-out internal reset v bot- v bot+ t tout ck cc bit 76543210 jtd ? sm2 jtrf wdrf borf extrf porf mcucsr read/write r/w r/w r r/w r/w r/w r/w r/w initial value 0 0 0 see bit description 52 2513k?avr?07/09 atmega162/v ? bit 2 ? borf: brown-out reset flag this bit is set if a brown-out reset occurs. the bi t is reset by a power-on reset, or by writing a logic zero to the flag. ? bit 1 ? extrf: external reset flag this bit is set if an external reset occurs. the bit is reset by a power-on reset, or by writing a logic zero to the flag. ? bit 0 ? porf: power-on reset flag this bit is set if a power-on reset occurs. the bit is reset only by writing a logic zero to the flag. to make use of the reset flags to identify a reset condition, the user should read and then reset the mcucsr as early as possible in the pr ogram. if the register is cleared before another reset occurs, the source of the reset can be found by examining the reset flags. internal voltage reference atmega162 features an internal bandgap reference. this reference is used for brown-out detection, and it can be used as an input to the analog comparator. voltage reference enable signals and start-up time the voltage reference has a start-up time that may influence the way it should be used. the start-up time is given in table 21 . to save power, the reference is not always turned on. the ref- erence is on during the following situations: 1. when the bod is enabled (by programming the bodlevel fuses). 2. when the bandgap reference is connected to the analog comparator (by setting the acbg bit in acsr). thus, when the bod is not enabled, after setting the acbg bit, the user must always allow the reference to start up before the output from the analog comparator is used. to reduce power consumption in power-down mode, the user c an avoid the two conditions above to ensure that the reference is turned off before entering power-down mode. watchdog timer the watchdog timer is clocked fr om a separate on-chip oscillato r which runs at 1 mhz. this is the typical frequency at v cc = 5v. see characterization data for typical values at other v cc lev- els. by controlling the watchdog timer prescaler, the watchdog reset interval can be adjusted as shown in table 23 on page 54 . the wdr ? watchdog reset ? instruction resets the watch- dog timer. the watchdog timer is also reset when it is disabled and when a chip reset occurs. eight different clock cycle periods can be selected to determine the reset period. if the reset period expires without another watchdog reset, the atmega162 resets and executes from the reset vector. for timing details on the watchdog reset, refer to page 54 . to prevent unintentional disabling of the watchdog or unintentional change of time-out period, 3 different safety levels are selected by the fuses m161c and wdton as shown in table 22. safety level 0 corresponds to the setting in atmega161. there is no restriction on enabling the table 21. internal voltage reference characteristics symbol parameter min. typ. max. units v bg bandgap reference voltage 1.05 1.10 1.15 v t bg bandgap reference start-up time 40 70 s i bg bandgap reference current consumption 10 a 53 2513k?avr?07/09 atmega162/v wdt in any of the safety levels. refer to ?timed sequences for changing the configuration of the watchdog timer? on page 56 for details. figure 27. watchdog timer watchdog timer control register ? wdtcr ? bits 7..5 ? res: reserved bits these bits are reserved bits in the atmega162 and will always read as zero. ? bit 4 ? wdce: watchdog change enable this bit must be set when the wde bit is writte n to logic zero. otherwis e, the watchdog will not be disabled. once written to one, hardware will clear this bit after four clock cycles. refer to the description of the wde bit for a watchdog disable procedure. in safety levels 1 and 2, this bit must also be set when changing the prescaler bits. see ?timed sequences for changing the configuration of the watchdog timer? on page 56. ? bit 3 ? wde: watchdog enable when the wde is written to logic one, the watchdog timer is enabled, and if the wde is written to logic zero, the watchdog timer function is di sabled. wde can only be cleared if the wdce bit has logic level one. to disable an enabled watchdog timer, the following procedure must be followed: table 22. wdt configuration as a function of the fuse settings of m161c and wdton. m161c wdton safety level wdt initial state how to disable the wdt how to change time- out unprogrammed unprogrammed 1 disabled timed sequence timed sequence unprogrammed programmed 2 enabled always enabled timed sequence programmed unprogrammed 0 disabled timed sequence no restriction programmed programmed 2 enabled always enabled timed sequence watchdog oscillator bit 76543210 ? ? ? wdce wde wdp2 wdp1 wdp0 wdtcr read/write r r r r/w r/w r/w r/w r/w initial value00000000 54 2513k?avr?07/09 atmega162/v 1. in the same operation, write a logic one to wdce and wde. a logic one must be written to wde even though it is set to one before the disable operation starts. 2. within the next four clock cycles, write a logic 0 to wde. this disables the watchdog. in safety level 2, it is not possible to disable the watchdog timer, even with the algorithm described above. see ?timed sequences for changing the configuration of the watchdog timer? on page 56. ? bits 2..0 ? wdp2, wdp1, wdp0: watchdog timer prescaler 2, 1, and 0 the wdp2, wdp1, and wdp0 bits determine the watchdog timer prescaling when the watch- dog timer is enabled. the different prescaling values and their corresponding timeout periods are shown in table 23 . table 23. watchdog timer prescale select wdp2 wdp1 wdp0 number of wdt oscillator cycles typical time-out at v cc = 3.0v typical time-out at v cc = 5.0v 0 0 0 16k (16,384) 17 ms 16 ms 0 0 1 32k (32,768) 34 ms 33 ms 0 1 0 65k (65,536) 69 ms 65 ms 0 1 1 128k (131,072) 0.14 s 0.13 s 1 0 0 256k (262,144) 0.27 s 0.26 s 1 0 1 512k (524,288) 0.55 s 0.52 s 1 1 0 1,024k (1,048,576) 1.1 s 1.0 s 1 1 1 2,048k (2,097,152) 2.2 s 2.1 s 55 2513k?avr?07/09 atmega162/v the following code example shows one assembly and one c function for turning off the wdt. the example assumes that interrupts are controlled (e.g., by disabling interrupts globally) so that no interrupts will occur during execution of these functions. assembly code example wdt_off: ; reset wdt wdr ; write logical one to w?ce and wde in r16, wdtcr ori r16, (1< 57 2513k?avr?07/09 atmega162/v interrupts this section describes the specifics of the interrupt handling as performed in atmega162. for a general explanation of the avr interrupt handling, refer to ?reset and interrupt handling? on page 14 . table 24 shows the interrupt table when the compatibility fuse (m161c) is unpro- grammed, while table 25 shows the interrupt table when m161c fuse is programmed. all assembly code examples in this sections are using the interrupt table when the m161c fuse is unprogrammed. interrupt vectors in atmega162 table 24. reset and interrupt vectors if m161c is unprogrammed vector no. program address (2) source interrupt definition 10x000 (1) reset external pin, power-on reset, brown-out reset, watchdog reset, and jtag avr reset 2 0x002 int0 external interrupt request 0 3 0x004 int1 external interrupt request 1 4 0x006 int2 external interrupt request 2 5 0x008 pcint0 pin change interrupt request 0 6 0x00a pcint1 pin change interrupt request 1 7 0x00c timer3 capt timer/counter3 capture event 8 0x00e timer3 compa timer/counter3 compare match a 9 0x010 timer3 compb timer/counter3 compare match b 10 0x012 timer3 ovf timer/counter3 overflow 11 0x014 timer2 comp timer/counter2 compare match 12 0x016 timer2 ovf timer/counter2 overflow 13 0x018 timer1 capt timer/counter1 capture event 14 0x01a timer1 compa timer/counter1 compare match a 15 0x01c timer1 compb timer/counter1 compare match b 16 0x01e timer1 ovf timer/counter1 overflow 17 0x020 timer0 comp timer/counter0 compare match 18 0x022 timer0 ovf timer/counter0 overflow 19 0x024 spi, stc serial transfer complete 20 0x026 usart0, rxc usart0, rx complete 21 0x028 usart1, rxc usart1, rx complete 22 0x02a usart0, udre usart0 data register empty 23 0x02c usart1, udre usart1 data register empty 24 0x02e usart0, txc usart0, tx complete 25 0x030 usart1, txc usart1, tx complete 26 0x032 ee_rdy eeprom ready 27 0x034 ana_comp analog comparator 28 0x036 spm_rdy store program memory ready 58 2513k?avr?07/09 atmega162/v notes: 1. when the bootrst fuse is programmed, the device will jump to the boot loader address at reset, see ?boot loader support ? read-while-write self-programming? on page 217 . 2. when the ivsel bit in gicr is set, interrupt vectors will be moved to the start of the boot flash section. the address of each interrupt vect or will then be the address in this table added to the start address of the boot flash section. notes: 1. when the bootrst fuse is programmed, the device will jump to the boot loader address at reset, see ?boot loader support ? read-while-write self-programming? on page 217 . 2. when the ivsel bit in gicr is set, interrupt vectors will be moved to the start of the boot flash section. the address of each interrupt vect or will then be the address in this table added to the start address of the boot flash section. table 25. reset and interrupt vectors if m161c is programmed vector no. program address (2) source interrupt definition 10x000 (1) reset external pin, power-on reset, brown-out reset, watchdog reset, and jtag avr reset 2 0x002 int0 external interrupt request 0 3 0x004 int1 external interrupt request 1 4 0x006 int2 external interrupt request 2 5 0x008 timer2 comp timer/counter2 compare match 6 0x00a timer2 ovf timer/counter2 overflow 7 0x00c timer1 capt timer/counter1 capture event 8 0x00e timer1 compa timer/counter1 compare match a 9 0x010 timer1 compb timer/counter1 compare match b 10 0x012 timer1 ovf timer/counter1 overflow 11 0x014 timer0 comp timer/counter0 compare match 12 0x016 timer0 ovf timer/counter0 overflow 13 0x018 spi, stc serial transfer complete 14 0x01a usart0, rxc usart0, rx complete 15 0x01c usart1, rxc usart1, rx complete 16 0x01e usart0, udre usart0 data register empty 17 0x020 usart1, udre usart1 data register empty 18 0x022 usart0, txc usart0, tx complete 19 0x024 usart1, txc usart1, tx complete 20 0x026 ee_rdy eeprom ready 21 0x028 ana_comp analog comparator 22 0x02a spm_rdy store program memory ready 59 2513k?avr?07/09 atmega162/v table 26 shows reset and interrupt vectors plac ement for the various combinations of bootrst and ivsel settings. if the program never enables an in terrupt source, the interrupt vectors are not used, and regular program code can be placed at these locations. this is also the case if the reset vector is in the application section while the interrupt vectors are in the boot section or vice versa. note: 1. the boot reset address is shown in table 93 on page 228 . for the bootrst fuse ?1? means unprogrammed while ?0? means programmed. the most typical and general program setup for the reset and interrupt vector addresses in atmega162 is: address labels code comments 0x000 jmp reset ; reset handler 0x002 jmp ext_int0 ; irq0 handler 0x004 jmp ext_int1 ; irq1 handler 0x006 jmp ext_int2 ; irq2 handler 0x008 jmp pcint0 ; pcint0 handler 0x00a jmp pcint1 ; pcint1 handler 0x00c jmp tim3_capt ; timer3 capture handler 0x00e jmp tim3_compa ; timer3 comparea handler 0x010 jmp tim3_compb ; timer3 compareb handler 0x012 jmp tim3_ovf ; timer3 overflow handler 0x014 jmp tim2_comp ; timer2 compare handler 0x016 jmp tim2_ovf ; timer2 overflow handler 0x018 jmp tim1_capt ; timer1 capture handler 0x01a jmp tim1_compa ; timer1 comparea handler 0x01c jmp tim1_compb ; timer1 compareb handler 0x01e jmp tim1_ovf ; timer1 overflow handler 0x020 jmp tim0_comp ; timer0 compare handler 0x022 jmp tim0_ovf ; timer0 overflow handler 0x024 jmp spi_stc ; spi transfer complete handler 0x026 jmp usart0_rxc ; usart0 rx complete handler 0x028 jmp usart1_rxc ; usart1 rx complete handler 0x02a jmp usart0_udre ; udr0 empty handler 0x02c jmp usart1_udre ; udr1 empty handler 0x02e jmp usart0_txc ; usart0 tx complete handler 0x030 jmp usart1_txc ; usart1 tx complete handler 0x032 jmp ee_rdy ; eeprom ready handler 0x034 jmp ana_comp ; analog comparator handler 0x036 jmp spm_rdy ; store program memory ready handler ; 0x038 reset: ldi r16,high(ramend) ; main program start 0x039 out sph,r16 ; set stack pointer to top of ram table 26. reset and interrupt vectors placement (1) bootrst ivsel reset address interr upt vectors start address 1 0 0x0000 0x0002 1 1 0x0000 boot reset address + 0x0002 0 0 boot reset address 0x0002 0 1 boot reset address boot reset address + 0x0002 60 2513k?avr?07/09 atmega162/v 0x03a ldi r16,low(ramend) 0x03b out spl,r16 0x03c sei ; enable interrupts 0x03d 61 2513k?avr?07/09 atmega162/v when the bootrst fuse is programmed, the boot section size set to 2k bytes and the ivsel bit in the gicr register is set before any in terrupts are enabled, the most typical and general program setup for the reset and interrupt vector addresses is: address labels code comments .org 0x1c00 0x1c00 jmp reset ; reset handler 0x1c02 jmp ext_int0 ; irq0 handler 0x1c04 jmp ext_int1 ; irq1 handler ... .... .. ; 0x1c36 jmp spm_rdy ; store program memory ready handler ; 0x1c38 reset: ldi r16,high(ramend) ; main program start 0x1c39 out sph,r16 ; set stack pointer to top of ram 0x1c3a ldi r16,low(ramend) 0x1c3b out spl,r16 0x1c3c sei ; enable interrupts 0x1c3d 62 2513k?avr?07/09 atmega162/v ? bit 0 ? ivce: interrupt vector change enable the ivce bit must be written to logic one to enable change of the ivsel bit. ivce is cleared by hardware four cyc les after it is written or when ivsel is written. sett ing the ivce bit will disable interrupts, as explained in the ivsel description above. see code example below. assembly code example move_interrupts: ; enable change of inter?upt vectors ldi r16, (1< 64 2513k?avr?07/09 atmega162/v figure 29. general digital i/o (1) note: 1. wpx, wdx, rrx, rpx, and rdx are common to all pins within the same port. clk i/o , sleep, and pud are common to all ports. configuring the pin each port pin consists of three register bits: ddxn, portxn, and pinxn. as shown in ?register description for i/o-ports? on page 82 , the ddxn bits are accessed at the ddrx i/o address, the portxn bits at the portx i/o address, and the pinxn bits at the pinx i/o address. the ddxn bit in the ddrx register selects the direct ion of this pin. if ddxn is written logic one, pxn is configured as an output pin. if ddxn is written logic zero, pxn is configured as an input pin. if portxn is written logic one when the pin is c onfigured as an input pin, the pull-up resistor is activated. to switch the pull-up resistor off, portxn has to be written logic zero or the pin has to be configured as an output pin. the port pins are tri-stated when a reset condition becomes active, even if no clocks are running. if portxn is written logic one when the pin is conf igured as an output pin, the port pin is driven high (one). if portxn is written logic zero when the pin is configured as an output pin, the port pin is driven low (zero). when switching between tri-state ({ddxn, portxn} = 0b00) and output high ({ddxn, portxn} = 0b11), an intermediate state with either pull-up enabled ({ddxn, portxn} = 0b01) or output low ({ddxn, portxn} = 0b10) must occur. norma lly, the pull-up enabled state is fully accept- able, as a high-impedant enviro nment will not notice the differenc e between a strong high driver and a pull-up. if this is not the case, the pud bit in the sfior register can be set to disable all pull-ups in all ports. clk rpx rrx wrx rdx wdx pud synchronizer wdx: write ddrx wrx: write portx rrx: read portx register rpx: read portx pin pud: pullup disable clk i/o : i/o clock rdx: read ddrx d l q q reset reset q q d q q d clr portxn q q d clr ddxn pinxn data b u s sleep sleep: sleep control pxn i/o 65 2513k?avr?07/09 atmega162/v switching between input with pull-up and output low generates the same problem. the user must use either the tri-state ({ddxn, portxn} = 0b00) or the output high state ({ddxn, portxn} = 0b11) as an intermediate step. table 27 summarizes the control signals for the pin value. reading the pin value independent of the setting of data direction bit ddxn, the port pin can be read through the pinxn register bit. as shown in figure 29 , the pinxn register bit and the preceding latch consti- tute a synchronizer. this is needed to avoid me tastability if the physical pin changes value near the edge of the internal clock, but it also introduces a delay. figure 30 shows a timing diagram of the synchronization when reading an externally applied pin val ue. the maximum and minimum propagation delays are denoted t pd,max and t pd,min respectively. figure 30. synchronization when reading an externally applied pin value table 27. port pin configurations ddxn portxn pud (in sfior) i/o pull-up comment 0 0 x input no tri-state (hi-z) 0 1 0 input yes pxn will source current if ext. pulled low. 0 1 1 input no tri-state (hi-z) 1 0 x output no output low (sink) 1 1 x output no output high (source) xxx in r17, pinx 0x00 0xff instructions sync latch pinxn r17 xxx system clk t pd, max t pd, min 66 2513k?avr?07/09 atmega162/v consider the clock period starting shortly after the first falling edge of th e system clock. the latch is closed when the clock is low, and goes transpa rent when the clock is high, as indicated by the shaded region of the ?sync latch? signal. the signal value is latched when the system clock goes low. it is clocked into the pinxn register at the succeeding positive clock edge. as indi- cated by the two arrows t pd,max and t pd,min , a single signal transiti on on the pin will be delayed between ? and 1? system clock period depending upon the time of assertion. when reading back a software assigned pin value, a nop instruction must be inserted as indi- cated in figure 31 . the out instruction sets the ?sync latch? signal at the positive edge of the clock. in this case, the delay t pd through the synchronizer is one system clock period. figure 31. synchronization when reading a software assigned pin value out portx, r16 nop in r17, pinx 0xff 0x00 0xff system clk r16 instructions sync latch pinxn r17 t pd 67 2513k?avr?07/09 atmega162/v the following code example shows how to set port b pins 0 and 1 high, 2 and 3 low, and define the port pins from 4 to 7 as input with pull-ups assigned to port pins 6 and 7. the resulting pin values are read back again, but as previously discussed, a nop instruction is included to be able to read back the value recently assigned to some of the pins. note: 1. for the assembly program, two temporary registers are used to minimize the time from pull- ups are set on pins 0, 1, 6, and 7, until the di rection bits are correctly set, defining bit 2 and 3 as low and redefining bits 0 and 1 as strong high drivers. digital input enable and sleep modes as shown in figure 29 , the digital input signal can be clamped to ground at the input of the schmitt trigger. the signal deno ted sleep in the figure, is set by the mcu sleep controller in power-down mode, power-save mode, standby mode, and extended standby mode to avoid high power consumption if some input signals are left floating, or have an analog signal level close to v cc /2. sleep is overridden for port pins enabled as exte rnal interrupt pins. if the external interrupt request is not enabled, sleep is active also fo r these pins. sleep is also overridden by vari- ous other alternate functions as described in ?alternate port functions? on page 68 . if a logic high level (?one?) is present on an asynchronous external interrupt pin configured as ?interrupt on rising edge, falling edge, or any logic change on pin? while the external interrupt is not enabled, the corresponding external interrupt flag will be set when resuming from the above mentioned sleep modes, as the clamping in these sleep modes produces the requested logic change. assembly code example (1) ... ; define pull-ups a?d set outputs high ; define directions?for port pins ldi r16,(1< 69 2513k?avr?07/09 atmega162/v table 28 summarizes the function of the overriding signals. the pin and port indexes from fig- ure 32 are not shown in the succeeding tables. the overriding signals are generated internally in the modules having the alternate function. the following subsections shortly describe the alternate functions for each port, and relate the overriding signals to the alternate function. refer to the alternate function description for further details. table 28. generic description of overriding signals for alternate functions. signal name full name description puoe pull-up override enable if this signal is set, the pull-up enable is controlled by the puov signal. if this signal is cleared, the pull-up is enabled when {ddxn, portxn, pud} = 0b010. puov pull-up override value if puoe is set, the pull-up is enabled/disabled when puov is set/cleared, regardless of the setting of the ddxn, portxn, and pud register bits. ddoe data direction override enable if this signal is set, the output driver enable is controlled by the ddov signal. if this signal is cleared, the output driver is enabled by the ddxn register bit. ddov data direction override value if ddoe is set, the output driver is enabled/disabled when ddov is set/cleared, regar dless of the setting of the ddxn register bit. pvoe port value override enable if this signal is set and the output driver is enabled, the port value is controlled by the pvov signal. if pvoe is cleared, and the output driver is enabled, the port value is controlled by the portxn register bit. pvov port value override value if pvoe is set, the port value is set to pvov, regardless of the setting of the portxn register bit. dieoe digital input enable override enable if this bit is set, the digital input enable is controlled by the dieov signal. if this signal is cleared, the digital input enable is determined by mcu state (normal mode, sleep modes). dieov digital input enable override value if dieoe is set, the digital i nput is enabled/disabled when dieov is set/cleared, regardless of the mcu state (normal mode, sleep modes). di digital input this is the digital input to alternate functions. in the figure, the signal is connected to t he output of the schmitt trigger but before the synchronizer. unless the digital input is used as a clock source, the module with the alternate function will use its own synchronizer. aio analog input/output this is the analog input/output to/from alternate functions. the signal is connected directly to the pad, and can be used bi-directionally. 70 2513k?avr?07/09 atmega162/v special function io register ? sfior ? bit 2 ? pud: pull-up disable when this bit is written to one, the pull-ups in the i/o ports are disabled even if the ddxn and portxn registers are configured to enable the pull-ups ({ddxn, portxn} = 0b01). see ?con- figuring the pin? on page 64 for more details about this feature. alternate functions of port a port a has an alternate function as the address low byte and data lines for the external memory interface and as pin change interrupt. table 30 and table 31 relate the alternate functions of port a to the overriding signals shown in figure 32 on page 68 . bit 7 6 5 4 3 2 1 0 tsm xmbk xmm2 xmm1 xmm0 pud psr2 psr310 sfior read/write r/w r/w r/w r/w r/w r/w r/w r/w initial value 0 0 0 0 0 0 0 0 table 29. port a pins alternate functions port pin alternate function pa 7 ad7 (external memory interface address and data bit 7) pcint7 (pin change interrupt 7) pa 6 ad6 (external memory interface address and data bit 6) pcint6 (pin change interrupt 6) pa 5 ad5 (external memory interface address and data bit 5) pcint5 (pin change interrupt 5) pa 4 ad4 (external memory interface address and data bit 4) pcint4 (pin change interrupt 4) pa 3 ad3 (external memory interface address and data bit 3) pcint3 (pin change interrupt 3) pa 2 ad2 (external memory interface address and data bit 2) pcint2 (pin change interrupt 2) pa 1 ad1 (external memory interface address and data bit 1) pcint1 (pin change interrupt 1) pa 0 ad0 (external memory interface address and data bit 0) pcint0 (pin change interrupt 0) 71 2513k?avr?07/09 atmega162/v notes: 1. ada is short for address active and represents the time when address is output. see ?exter- nal memory interface? on page 26. 2. pcintn is pin change interrupt enable bit n. 3. pcintn is pin change interrupt input n. notes: 1. pcint is pin change interrupt enable bit n. 2. pcint is pin change interrupt input n. table 30. overriding signals for alternate functions in pa7..pa4 signal name pa7/ad7/ pcint7 pa6/ad6/pcint6 pa5/ ad5/pcint5 pa4/ad4/pcint4 puoe sre sre sre sre puov ~(wr + ada (1) ) ? porta7 ~(wr + ada) ? porta6 ~(wr + ada) ? porta5 ~(wr + ada) ? porta4 ddoe sre sre sre sre ddov wr + ada wr + ada wr + ada wr + ada pvoe sre sre sre sre pvov if (ada) then a7 else d7 output ? wr if (ada) then a6 else d6 output ? wr if (ada) then a5 else d5 output ? wr if (ada) then a4 else d4 output ? wr dieoe (2 ) pcie0 ? pcint7 pcie0 ? pcint6 pcie0 ? pcint5 pcie0 ? pcint4 dieov1111 di (3) d7 input/ pcint7 d6 input/ pcint6 d5 input/ pcint5 d4 input/ pcint4 aio???? table 31. overriding signals for alternate functions in pa3..pa0 signal name pa3/ad3/ pcint3 pa2/ad2/ pcint2 pa1 /a d1/ pcint1 pa0 /ad 0/ pcint0 puoe sre sre sre sre puov ~(wr + ada) ? porta3 ~(wr + ada) ? porta2 ~(wr + ada) ? porta1 ~(wr + ada) ? porta0 ddoe sre sre sre sre ddov wr + ada wr + ada wr + ada wr + ada pvoe sre sre sre sre pvov if (ada) then a3 else d3 output ? wr if (ada) then a2 else d2 output ? wr if (ada) then a1 else d1 output ? wr if (ada) then a0 else d0 output ? wr dieoe (1) pcie0 ? pcint3 pcie0 ? pcint2 pcie0 ? pcint1 pcie0 ? pcint0 dieov 1 1 1 1 di (2) d3 input /pcint3 d2 input /pcint2 d1 input /pcint1 d0 input /pcint0 aio ? ? ? ? 72 2513k?avr?07/09 atmega162/v alternate functions of port b the port b pins with alternate functions are shown in table 32 . the alternate pin configuration is as follows: ? sck ? port b, bit 7 sck: master clock output, slave clock input pin for spi channel. when the spi is enabled as a slave, this pin is configured as an input r egardless of the setting of ddb7. when the spi is enabled as a master, the data direction of this pi n is controlled by ddb7. when the pin is forced by the spi to be an input, the pull-up can still be controlled by the portb7 bit. ? miso ? port b, bit 6 miso: master data input, slave data output pin for spi channel. when the spi is enabled as a master, this pin is configured as an input r egardless of the setting of ddb6. when the spi is enabled as a slave, the data direction of this pi n is controlled by ddb6. when the pin is forced by the spi to be an input, the pull-up can still be controlled by the portb6 bit. ? mosi ? port b, bit 5 mosi: spi master data output, slave data input for spi channel. when the spi is enabled as a slave, this pin is configured as an input r egardless of the setting of ddb5. when the spi is enabled as a master, the data direction of this pi n is controlled by ddb5. when the pin is forced by the spi to be an input, the pull-up can still be controlled by the portb5 bit. ?ss /oc3b ? port b, bit 4 ss : slave select input. when the spi is enabled as a slave, this pin is configured as an input regardless of the setting of ddb4. as a slave, the spi is activated when this pin is driven low. when the spi is enabled as a master, the data di rection of this pin is controlled by ddb4. when the pin is forced by the spi to be an input, th e pull-up can still be cont rolled by the portb4 bit. oc3b, output compare match b output: the pb4 pin can serve as an external output for the timer/counter3 output compare b. the pin has to be configured as an output (ddb4 set (one)) to serve this function. the oc3b pin is also the output pin for the pwm mode timer function. table 32. port b pins alternate functions port pin alternate functions pb7 sck (spi bus serial clock) pb6 miso (spi bus master input/slave output) pb5 mosi (spi bus master output/slave input) pb4 ss (spi slave select input) oc3b (timer/counter3 outp ut compare match output) pb3 ain1 (analog comparator negative input) txd1 (usart1 output pin) pb2 ain0 (analog comparator positive input) rxd1 (usart1 input pin) pb1 t1 (timer/counter1 external counter input) oc2 (timer/counter2 output compare match output) pb0 t0 (timer/counter0 external counter input) oc0 (timer/counter0 output compare match output) clk i/o (divided system clock) 73 2513k?avr?07/09 atmega162/v ? ain1/txd1 ? port b, bit 3 ain1, analog comparator negative input. configure the port pin as input with the internal pull-up switched off to avoid the digital port function fr om interfering with the function of the analog comparator. txd1, transmit data (data output pin for usart1). when the usart1 transmitter is enabled, this pin is configured as an output regardless of the value of ddb3. ? ain0/rxd1 ? port b, bit 2 ain0, analog comparator positive input. configure the port pin as input with the internal pull-up switched off to avoid the digital port function fr om interfering with the function of the analog comparator. rxd1, receive data (data input pin for usart1). when the usart1 receiver is enabled this pin is configured as an input regardless of the value of ddb2. when the usart1 forces this pin to be an input, the pull-up can st ill be controlled by the portb2 bit. ? t1/oc2 ? port b, bit 1 t1, timer/counter1 counter source. oc2, output compare match output: the pb1 pin can serve as an external output for the timer/counter2 compare match. the pb1 pin has to be configured as an output (ddb1 set (one)) to serve this function. the oc2 pin is also the output pin for the pwm mode timer function. ? t0/oc0 ? port b, bit 0 t0, timer/counter0 counter source. oc0, output compare match output: the pb0 pin can serve as an external output for the timer/counter0 compare match. the pb0 pin has to be configured as an output (ddb0 set (one)) to serve this function. the oc0 pin is also the output pin for the pwm mode timer function. clk i/o , divided system clock: t he divided system clock can be output on the pb0 pin. the divided system clock will be output if the ck out fuse is programmed, regardless of the portb0 and ddb0 settings. it will also be output during reset. table 33 and table 34 relate the alternate functions of port b to the overriding signals shown in figure 32 on page 68 . spi mstr input and spi slave outp ut constitute t he miso signal, while mosi is divided into spi mstr output and spi slave input. 74 2513k?avr?07/09 atmega162/v notes: 1. ckout is one if the ckout fuse is programmed. 2. clk i/o is the divided system clock. table 33. overriding signals for alternate functions in pb7..pb4 signal name pb7/sck pb6/mis o pb5/mosi pb4/ss/ oc3b puoe spe ? mstr spe ? mstr spe ? mstr spe ? mstr puov portb7 ? pud portb6 ? pud portb5 ? pud portb4 ? pud ddoe spe ? mstr spe ? mstr spe ? mstr spe ? mstr ddov 0 0 0 0 pvoe spe ? mstr spe ? mstr spe ? mstr oc3b enable pvov sck output spi slave output spi mstr output oc3b dieoe 0 0 0 0 dieov 0 0 0 0 di sck input spi mstr input spi slave input spi ss aio ? ? ? ? table 34. overriding signals for alternate functions in pb3..pb0 signal name pb3/ain1/txd1 pb2/ain0/rxd1 pb1/t1/oc2 pb0/t0/oc0 puoe txen1 rxen1 0 0 puov 0 portb2? pud 0 0 ddoe txen1 rxen1 0 ckout (1) ddov 1 0 0 1 pvoe txen1 0 oc2 enable ckout + oc0 enable pvov txd1 0 oc2 if (ckout) then clk i/o (2) else oc0 dieoe 0 0 0 0 dieov 0 0 0 0 di ? rxd1 t1 input t0 input aio ain1 input ain0 input ? ? 75 2513k?avr?07/09 atmega162/v alternate functions of port c the port c pins with alternate functions are shown in table 35 . if the jtag interface is enabled, the pull-up resistors on pins pc7(tdi), pc5(tms) and pc4(tck) will be activated even if a reset occurs. ? a15/tdi/pcint15 ? port c, bit 7 a15, external memory interface address bit 15. tdi, jtag test data in: serial input data to be shifted into the instruction register or data reg- ister (scan chains). when the jtag interface is enabled, this pin can not be used as an i/o pin. pcint15: the pin can also serve as a pin change interrupt. ? a14/tdo/pcint14 ? port c, bit 6 a14, external memory interface address bit 14. tdo, jtag test data out: serial output data from instruction register or data register. when the jtag interface is enabled, this pin can not be used as an i/o pin. in tap states that shift out data, the td0 pin drives actively. in other states the pin is pulled high. pcint14: the pin can also serve as a pin change interrupt. table 35. port c pins alternate functions port pin alternate function pc7 a15 (external memory interface address bit 15) tdi (jtag test data input) pcint15 (pin change interrupt 15) pc6 a14 (external memory interface address bit 14) tdo (jtag test data output) pcint14 (pin change interrupt 14) pc5 a13 (external memory interface address bit 13) tms (jtag test mode select) pcint13 (pin change interrupt 13) pc4 a12 (external memory interface address bit 12) tck (jtag test clock) pcint12 (pin change interrupt 12) pc3 a11 (external memory interface address bit 11) pcint11 (pin change interrupt 11) pc2 a10 (external memory interface address bit 10) pcint10 (pin change interrupt 10) pc1 a9 (external memory interface address bit 9) pcint9 (pin change interrupt 9) pc0 a8 (external memory interface address bit 8) pcint8 (pin change interrupt 8) 76 2513k?avr?07/09 atmega162/v ? a13/tms/pcint13 ? port c, bit 5 a13, external memory interface address bit 13. tms, jtag test mode select: this pin is used for navigating through the tap-controller state machine. when the jtag interface is enabled, this pin can not be used as an i/o pin. pcint13: the pin can also serve as a pin change interrupt. ? a12/tck/pcint12 ? port c, bit 4 a12, external memory interface address bit 12. tck, jtag test clock: jtag operation is sync hronous to tck. when the jtag interface is enabled, this pin can not be used as an i/o pin. pcint12: the pin can also serve as a pin change interrupt. ? a11/pcint11 ? port c, bit 3 a11, external memory interface address bit 11. pcint11: the pin can also serve as a pin change interrupt. ? a10/pcint10 ? port c, bit 2 a10, external memory interface address bit 10. pcint11: the pin can also serve as a pin change interrupt. ? a9/pcint9 ? port c, bit 1 a9, external memory interface address bit 9. pcint9: the pin can also serve as a pin change interrupt. ? a8/pcint8 ? port c, bit 0 a8, external memory interface address bit 8. pcint8: the pin can also serve as a pin change interrupt. table 36 and table 37 relate the alternate functions of port c to the overriding signals shown in figure 32 on page 68 . 77 2513k?avr?07/09 atmega162/v notes: 1. pcintn is pin change interrupt enable bit n. 2. pcintn is pin change interrupt input n. notes: 1. pcintn is pin change interrupt enable bit n. 2. pcintn is pin change interrupt input n. table 36. overriding signals for alternate functions in pc7..pc4 signal name pc7/a15/tdi /pcint15 pc6/a14/tdo /pcint14 pc5/a13/tms /pcint13 pc4/a12/tck /pcint12 puoe (xmm < 1) ? sre + jtagen (xmm < 2) ? sre +jtagen (xmm < 3) ? sre + jtagen (xmm < 4) ? sre + jtagen puov jtagen jtagen jtagen jtagen ddoe sre ? (xmm<1) + jtagen sre ? (xmm<2) + jtagen sre ? (xmm<3) + jtagen sre ? (xmm<4) + jtagen ddov jtagen jtagen + jtagen ? (shift_ir | shift_dr) jtagen jtagen pvoe sre ? (xmm<1) sre ? (xmm<2) + jtagen sre ? (xmm<3) sre ? (xmm<4) pvov a15 if (jtagen) then tdo else a14 a13 a12 dieoe (1) jtagen | pcie1 ? pcint15 jtagen | pcie1 ? pcint14 jtagen | pcie1 ? pcint13 jtagen | pcie1 ? pcint12 dieov jtagen jtagen jtagen jtagen di (2) pcint15 pcint14 pcint13 pcint12 aio tdi ? tms tck table 37. overriding signals for alternate functions in pc3..pc0 signal name pc3/a11/ pcint11 pc2/a10/ pcint10 pc1/a9/pcint9 pc0/a8/pcint8 puoe sre ? (xmm<5) sre ? (xmm<6) sre ? (xmm<7) sre ? (xmm<7) puov0000 ddoe sre ? (xmm<5) sre ? (xmm<6) sre ? (xmm<7) sre ? (xmm<7) ddov 1 1 1 1 pvoe sre ? (xmm<5) sre ? (xmm<6) sre ? (xmm<7) sre ? (xmm<7) pvov a11 a10 a9 a8 dieoe (1) pcie1 ? pcint11 pcie1 ? pcint10 pcie1 ? pcint9 pcie1 ? pcint8 dieov1111 di (2) pcint11 pcint10 pcint9 pcint8 aio???? 78 2513k?avr?07/09 atmega162/v alternate functions of port d the port d pins with alternate functions are shown in table 38 . the alternate pin configuration is as follows: ?rd ? port d, bit 7 rd is the external data memory read control strobe. ?w r ? port d, bit 6 wr is the external data memory write control strobe. ? tosc2/oc1a ? port d, bit 5 tosc2, timer oscillator pin 2: when the as2 bit in assr is se t (one) to enabl e asynchronous clocking of timer/counter2, pin pd5 is disconnected from the port, and becomes the inverting output of the oscillator amplifier. in this mode, a crystal oscillator is connected to this pin, and the pin can not be used as an i/o pin. oc1a, output compare match a output: the pd5 pin can serve as an external output for the timer/counter1 output compare a. the pin has to be configured as an output (ddd5 set (one)) to serve this function. the oc1a pin is also the output pin for the pwm mode timer function. table 38. port d pins alternate functions port pin alternate function pd7 rd (read strobe to external memory) pd6 wr (write strobe to external memory) pd5 tosc2 (timer oscillator pin 2) oc1a (timer/counter1 output compare a match output) pd4 tosc1 (timer oscillator pin 1) xck0 (usart0 external clock input/output) oc3a (timer/counter3 output compare a match output) pd3 int1 (external interrupt 1 input) icp3 (timer/counter3 input capture pin) pd2 int0 (external interrupt 0 input) xck1 (usart1 external clock input/output) pd1 txd0 (usart0 output pin) pd0 rxd0 (usart0 input pin) 79 2513k?avr?07/09 atmega162/v ? tosc1/xck0/oc3a ? port d, bit 4 tosc1, timer oscillator pin 1: when the as2 bit in assr is se t (one) to enabl e asynchronous clocking of timer/counter2, pin pd4 is disconnecte d from the port, and becomes the input of the inverting oscillator amplifier. in this mode, a cr ystal oscillator is connected to this pin, and the pin can not be used as an i/o pin. xck0, usart0 external clock: the data direction register (ddd4) controls whether the clock is output (ddd4 set (one)) or input (ddd4 cleared (zero)). the xck0 pin is active only when usart0 operates in synchronous mode. oc3a, output compare match a output: the pd4 pin can serve as an external output for the timer/counter1 output compare a. the pin has to be configured as an output (ddd4 set (one)) to serve this function. the oc4a pin is also the output pin for the pwm mode timer function. ? int1/icp3 ? port d, bit 3 int1, external interrupt source 1: the pd3 pin can serve as an external interrupt source. icp3, input capture pin: the pd3 pin can act as an input capture pin for timer/counter3. ? int0/xck1 ? port d, bit 2 int0, external interrupt source 0: the pd2 pin can serve as an external interrupt source. xck1, usart1 external clock: the data direction register (ddd2) controls whether the clock is output (ddd2 set (one)) or input (ddd2 cleared (zero)). the xck1 pin is active only when usart1 operates in synchronous mode. ? txd0 ? port d, bit 1 txd0, transmit data (data output pin for usart0). when the usart0 transmitter is enabled, this pin is configured as an out put regardless of the value of ddd1. 80 2513k?avr?07/09 atmega162/v ? rxd0 ? port d, bit 0 rxd0, receive data (data input pin for usart0). when the usart0 receiver is enabled this pin is configured as an input regardless of the value of ddd0. when usart0 forces this pin to be an input, the pull- up can still be controlled by the portd0 bit. table 39 and table 40 relate the alternate functions of port d to the overriding signals shown in figure 32 on page 68 . table 39. overriding signals for alternate functions pd7..pd4 signal name pd7/rd pd6/wr pd5/tosc2/oc1a pd4/tosc1/xck0/oc3a puoe sre sre as2 as2 puov 0 0 0 0 ddoe sre sre as2 as2 ddov 1 1 0 0 pvoe sre sre oc1a enable xck0 output enable | oc3a enable pvov rd wr oc1a if (xck0 output enable) then xck0 output else oc3a dieoe 0 0 as2 as2 dieov 0 0 0 0 di ? ? ? xck0 input aio ? ? t/c2 osc output t/c2 osc input table 40. overriding signals for alternate functions in pd3..pd0 signal name pd3/int1 pd2/ int0/xck1 pd1/txd0 pd0/rxd0 puoe 0 0 txen0 rxen0 puov 0 0 0 portd0 ? pud ddoe 0 0 txen0 rxen0 ddov 0 0 1 0 pvoe 0 xck1 output enable txen0 0 pvov 0 xck1 txd0 0 dieoe int1 enable int0 enable 0 0 dieov 1 1 0 0 di int1 input/ icp1 input int0 input/xck1 input ? rxd0 aio ? ? ? ? 81 2513k?avr?07/09 atmega162/v alternate functions of port e the port e pins with alternate functions are shown in table 41 . the alternate pin configuration is as follows: ? oc1b ? port e, bit 2 oc1b, output compare match b output: the pe2 pin can serve as an external output for the timer/counter1 output compare b. the pin has to be configured as an output (dde0 set (one)) to serve this function. the oc1b pin is also the output pin for the pwm mode timer function. table 42 relate the alternate functions of port e to the overriding signals shown in figure 32 on page 68 . ?ale ? port e, bit 1 ale is the external data memory address latch enable signal. ? icp1/int2 ? port e, bit 0 icp1, input capture pin: the pe0 pin can act as an input capture pin for timer/counter1. int2, external interrupt source 2: the pe0 pin can serve as an external interrupt source. table 41. port e pins alternate functions port pin alternate function pe2 oc1b (timer/counter1 output compareb match output) pe1 ale (address latch enable to external memory) pe0 icp1 (timer/counter1 input capture pin) int2 (external interrupt 2 input) table 42. overriding signals for alternate functions pe2..pe0 signal name pe2 pe1 pe0 puoe 0 sre 0 puov 0 0 0 ddoe 0 sre 0 ddov 0 1 0 pvoe oc1b enable sre 0 pvov oc1b ale 0 dieoe 0 0 int2 enabled dieov 0 0 1 di 0 0 int2 input/ icp1 input aio ? ? ? 82 2513k?avr?07/09 atmega162/v register description for i/o- ports port a data register ? porta port a data direction register ? ddra port a input pins address ? pina port b data register ? portb port b data direction register ? ddrb port b input pins address ? pinb port c data register ? portc port c data direction register ? ddrc bit 76543210 porta7 porta6 porta5 porta4 porta3 porta2 porta1 porta0 porta read/write r/w r/w r/w r/w r/w r/w r/w r/w initial value00000000 bit 76543210 dda7 dda6 dda5 dda4 dda3 dda2 dda1 dda0 ddra read/write r/w r/w r/w r/w r/w r/w r/w r/w initial value00000000 bit 76543210 pina7 pina6 pina5 pina4 pi na3 pina2 pina1 pina0 pina read/writerrrrrrrr initial value n/a n/a n/a n/a n/a n/a n/a n/a bit 76543210 portb7 portb6 portb5 portb4 portb3 portb2 portb1 portb0 portb read/write r/w r/w r/w r/w r/w r/w r/w r/w initial value00000000 bit 76543210 ddb7 ddb6 ddb5 ddb4 ddb3 ddb2 ddb1 ddb0 ddrb read/write r/w r/w r/w r/w r/w r/w r/w r/w initial value00000000 bit 76543210 pinb7 pinb6 pinb5 pinb4 pi nb3 pinb2 pinb1 pinb0 pinb read/writerrrrrrrr initial value n/a n/a n/a n/a n/a n/a n/a n/a bit 76543210 portc7 portc6 portc5 portc4 portc3 portc2 portc1 portc0 portc read/write r/w r/w r/w r/w r/w r/w r/w r/w initial value00000000 bit 76543210 ddc7 ddc6 ddc5 ddc4 ddc3 ddc2 ddc1 ddc0 ddrc read/write r/w r/w r/w r/w r/w r/w r/w r/w initial value00000000 83 2513k?avr?07/09 atmega162/v port c input pins address ? pinc port d data register ? portd port d data direction register ? ddrd port d input pins address ? pind port e data register ? porte port e data direction register ? ddre port e input pins address ? pine bit 76543210 pinc7 pinc6 pinc5 pinc4 pi nc3 pinc2 pinc1 pinc0 pinc read/writerrrrrrrr initial value n/a n/a n/a n/a n/a n/a n/a n/a bit 76543210 portd7 portd6 portd5 portd4 portd3 portd2 portd1 portd0 portd read/write r/w r/w r/w r/w r/w r/w r/w r/w initial value00000000 bit 76543210 ddd7 ddd6 ddd5 ddd4 ddd3 ddd2 ddd1 ddd0 ddrd read/write r/w r/w r/w r/w r/w r/w r/w r/w initial value00000000 bit 76543210 pind7 pind6 pind5 pind4 pi nd3 pind2 pind1 pind0 pind read/writerrrrrrrr initial value n/a n/a n/a n/a n/a n/a n/a n/a bit 76543210 ?????porte2porte1porte0porte read/writerrrrrr/wr/wr/w initial value00000000 bit 76543210 ?????dde2dde1dde0 ddre read/writerrrrrr/wr/wr/w initial value00000000 bit 76543210 ?????pine2pine1pine0pine read/writerrrrrrrr initial value00000n/an/an/a 84 2513k?avr?07/09 atmega162/v external interrupts the external interrupts are triggered by the int0, int1, int2 pin, or any of the pcint15..0 pins. observe that, if enabled, the in terrupts will trigger even if the int2..0 or pcint15..0 pins are configured as outputs. this feature provides a way of generating a software interrupt. the exter- nal interrupts can be triggered by a fa lling or rising edge or a low level (int2 is only an edge triggered interrupt). this is set up as indicate d in the specification fo r the mcu control register ? mcucr and extended mcu cont rol register ? emcucr. when the external interrupt is enabled and is configured as le vel triggered (only int0/int1), th e interrupt will trigger as long as the pin is held low. the pin chan ge interrupt pci1 will trigger if any enable d pcint15..8 pin tog- gles. pin change interrupts pci0 will trigger if any enabled pcint7..0 pin toggles. the pcmsk1 and pcmsk0 registers control which pins contribu te to the pin change interrupts. note that rec- ognition of falling or rising edge interrupts on int0 and int1 requires the presence of an i/o clock, described in ?clock systems and their distribution? on page 35 . low level interrupts on int0/int1, the edge interrupt on int2, and pin change interrupts on pcint15..0 are detected asynchronously. this implies that these interrupts can be used for waking the part also from sleep modes other than idle mode. the i/o clock is halted in all sleep modes except idle mode. note that if a level triggered interrupt is used for wake-up from power-down mode, the changed level must be held for some time to wake up the mcu. this makes the mcu less sensitive to noise. the changed level is sampled twice by the watchdog oscillator clock. the period of the watchdog oscillator is 1 s (nominal) at 5.0v and 25 c. the frequency of the watchdog oscilla- tor is voltage dependent as shown in ?electrical characteristics? on page 264 . the mcu will wake up if the input has the required level during this sampling or if it is held until the end of the start-up time. the start-up time is defined by the sut fuses as described in ?system clock and clock options? on page 35 . if the level is sampled twice by the watchdog oscillator clock but disappears before the end of th e start-up time, the mcu will stil l wake up, but no interrupt will be generated. the required level must be held long enough for the mcu to complete the wake up to trigger the level interrupt. mcu control register ? mcucr the mcu control register contains control bi ts for interrupt sense control and general mcu functions. ? bit 3, 2 ? isc11, isc10: interrupt sense control 1 bit 1 and bit 0 the external interrupt 1 is activated by the exte rnal pin int1 if the sreg i-bit and the corre- sponding interrupt mask in the gicr are set. the level and edges on the external int1 pin that activate the interrupt are defined in table 43 . the value on the int1 pin is sampled before detecting edges. if edge or toggle interrupt is selected, pulses that last longer than one clock period will generate an interrupt. shorter pulses are not guaranteed to generate an interrupt. if low level interrupt is selected, the low level must be held until the completion of the currently executing instruction to generate an interrupt. bit 76543210 sre srw10 se sm1 isc11 isc10 isc01 isc00 mcucr read/write r/w r/w r/w r/w r/w r/w r/w r/w initial value00000000 85 2513k?avr?07/09 atmega162/v ? bit 1, 0 ? isc01, isc00: interrupt sense control 0 bit 1 and bit 0 the external interrupt 0 is activated by the exte rnal pin int0 if the sreg i-flag and the corre- sponding interrupt mask are set. the level and edges on the external int0 pin that activate the interrupt are defined in table 44 . the value on the int0 pin is sampled before detecting edges. if edge or toggle interrupt is selected, pulses that last longer than one clock period will generate an interrupt. shorter pulses are not guaranteed to generate an interrupt. if low level interrupt is selected, the low level must be held until the completion of the currently executing instruction to generate an interrupt. extended mcu control register ? emcucr ? bit 0 ? isc2: interrupt sense control 2 the asynchronous external interrupt 2 is activated by the external pin int2 if the sreg i-bit and the corresponding interr upt mask in gicr are set. if isc2 is cleared (zero), a falling edge on int2 activates the interrupt. if isc2 is set (one), a rising edge on int2 activates the interrupt. edges on int2 are registered asynchronously . pulses on int2 wider than the minimum pulse width given in table 45 will generate an interrupt. shorter pu lses are not guar anteed to generate an interrupt. when changing the isc2 bit, an interrupt can occur. therefore, it is recommended to first disable int2 by clearing its interrupt enable bit in the gicr register. then, the isc2 bit can be changed. finally, the int2 interrupt flag should be cleared by writing a logical one to its interrupt flag bit (intf2) in the gifr register before the interrupt is re-enabled. table 43. interrupt 1 sense control isc11 isc10 description 0 0 the low level of int1 generates an interrupt request. 0 1 any logical change on int1 generates an interrupt request. 1 0 the falling edge of int1 generates an interrupt request. 1 1 the rising edge of int1 generates an interrupt request. table 44. interrupt 0 sense control isc01 isc00 description 0 0 the low level of int0 generates an interrupt request. 0 1 any logical change on int0 generates an interrupt request. 1 0 the falling edge of int0 generates an interrupt request. 1 1 the rising edge of int0 generates an interrupt request. bit 76543210 sm0 srl2 srl1 srl0 srw01 srw00 srw11 isc2 emcucr read/write r/w r/w r/w r/w r/w r/w r/w r/w initial value00000000 table 45. asynchronous external interrupt characteristics symbol parameter condition min. typ. max. units t int minimum pulse width for asynchronous external interrupt 50 ns 86 2513k?avr?07/09 atmega162/v general interrupt control register ? gicr ? bit 7 ? int1: external interrupt request 1 enable when the int1 bit is set (one) and the i-bit in the status register (sreg) is set (one), the exter- nal pin interrupt is enabled. the interrupt sense control1 bits 1/0 (isc11 and isc10) in the mcu general control register (mcucr) define whether the external interrupt is activated on rising and/or falling edge of the int1 pin or level sens ed. activity on the pin will cause an interrupt request even if int1 is configured as an output. the corresponding interrupt of external interrupt request 1 is executed from the int1 interrupt vector. ? bit 6 ? int0: external interrupt request 0 enable when the int0 bit is set (one) and the i-bit in the status register (sreg) is set (one), the exter- nal pin interrupt is enabled. the interrupt sense control0 bits 1/0 (isc01 and isc00) in the mcu general control register (mcucr) define whether the external interrupt is activated on rising and/or falling edge of the int0 pin or level sens ed. activity on the pin will cause an interrupt request even if int0 is configured as an output. the corresponding interrupt of external interrupt request 0 is executed from the int0 interrupt vector. ? bit 5 ? int2: external interrupt request 2 enable when the int2 bit is set (one) and the i-bit in the status register (sreg) is set (one), the exter- nal pin interrupt is enabled. the interrupt se nse control2 bit (isc2) in the extended mcu control register (emcucr) defines whether the ex ternal interrupt is acti vated on rising or fall- ing edge of the int2 pin. activity on the pi n will cause an interrupt request even if int2 is configured as an output. the corresponding interr upt of external interrupt request 2 is executed from the int2 interrupt vector. ? bit 4 ? pcie1: pin change interrupt enable 1 when the pcie1 bit is set (one) and the i-bit in the status register (sreg) is set (one), pin change interrupt 1 is enabled. any change on any enabled pcin t15..8 pin will cause an inter- rupt. the corresponding interrupt of pin change interrupt request is executed from the pci1 interrupt vector. pcint15..8 pins are enabled individually by the pcmsk1 register. ? bit 3 ? pcie0: pin change interrupt enable 0 when the pcie0 bit is set (one) and the i-bit in the status register (sreg) is set (one), pin change interrupt 0 is enabled. any change on any enabled pcint7..0 pin will cause an interrupt. the corresponding interrupt of pin change interrupt request is executed from the pci0 interrupt vector. pcint7..0 pins are enabled individually by the pcmsk0 register. bit 76543210 int1 int0 int2 pcie1 pcie0 ? ivsel ivce gicr read/write r/w r/w r/w r/w r/w r r/w r/w initial value 0 0 0 0 0 0 0 0 87 2513k?avr?07/09 atmega162/v general interrupt flag register ? gifr ? bit 7 ? intf1: external interrupt flag 1 when an edge or logic change on the int1 pin triggers an interrupt request, intf1 becomes set (one). if the i-bit in sreg and the int1 bit in gicr are set (one), the m cu will jump to the corre- sponding interrupt vector. the flag is cleared when the interrupt routine is executed. alternatively, the flag can be cleared by writing a logical one to it. this flag is always cleared when int1 is configured as a level interrupt. ? bit 6 ? intf0: external interrupt flag 0 when an edge or logic change on the int0 pin triggers an interrupt request, intf0 becomes set (one). if the i-bit in sreg and the int0 bit in gicr are set (one), the m cu will jump to the corre- sponding interrupt vector. the flag is cleared when the interrupt routine is executed. alternatively, the flag can be cleared by writing a logical one to it. this flag is always cleared when int0 is configured as a level interrupt. ? bit 5 ? intf2: external interrupt flag 2 when an event on the int2 pin triggers an interrupt request, intf2 becomes set (one). if the i- bit in sreg and the int2 bit in gicr are set (one), the mcu will jump to the corresponding interrupt vector. the flag is cleared when the inte rrupt routine is executed. alternatively, the flag can be cleared by writing a logical one to it. note that when entering some sleep modes with the int2 interrupt disabled, the input buffer on this pin will be disabled. this may cause a logic change in internal signals which will set the intf2 flag. see ?digital input enable and sleep modes? on page 67 for more information. ? bit 4 ? pcif1: pin change interrupt flag 1 when a logic change on any pcint15..8 pin triggers an interrupt request, pcif1 becomes set (one). if the i-bit in sreg and the pcie1 bit in gicr are set (o ne), the mcu will jump to the cor- responding interrupt vector. the flag is cleared when the interrupt routine is executed. alternatively, the flag can be cleared by writing a logical one to it. ? bit 3 ? pcif0: pin change interrupt flag 0 when a logic change on any pcint7..0 pin triggers an interrupt request, pcif0 becomes set (one). if the i-bit in sreg and the pcie0 bit in gicr are set (o ne), the mcu will jump to the cor- responding interrupt vector. the flag is cleared when the interrupt routine is executed. alternatively, the flag can be cleared by writing a logical one to it. bit 76543210 intf1 intf0 intf2 pcif1 pcif0 ? ? ?gifr read/write r/w r/w r/w r/w r/w r r r initial value 0 0 0 0 0 0 0 0 88 2513k?avr?07/09 atmega162/v pin change mask register 1 ? pcmsk1 ? bit 7..0 ? pcint15..8: pin change enable mask 15..8 each pcint15..8 bit selects whether pin change interrupt is enabled on the corresponding i/o pin. if pcint15..8 is set and the pcie1 bit in gicr is set, pin change interrupt is enabled on the corresponding i/o pin. if pcint15..8 is cleared, pin change interrupt on the corresponding i/o pin is disabled. pin change mask register 0 ? pcmsk0 ? bit 7..0 ? pcint7..0: pin change enable mask 7..0 each pcint7..0 bit selects whether pin change interrupt is enabled on the corresponding i/o pin. if pcint7..0 is set and the pcie0 bit in gicr is set, pin change interrupt is enabled on the corresponding i/o pin. if pcint7..0 is cleared, pin change interrupt on the corresponding i/o pin is disabled. the mapping between i/o pins and pcint bits can be found in figure 1 on page 2 . note that the pin change mask register are located in extended i/o. thus, the pin change interrupts are not supported in atmega161 com patibility mode. bit 76543210 pcint15 pcint14 pcint13 pcint12 pcint11 pcint10 pcint9 pcint9 pcmsk1 read/write r/w r/w r/w r/w r/w r/w r/w r/w initial value00000000 bit 76543210 pcint7 pcint6 pcint5 pcint4 pcint3 pcint2 pcint1 pcint0 pcmsk0 read/write r/w r/w r/w r/w r/w r/w r/w r/w initial value00000000 89 2513k?avr?07/09 atmega162/v 8-bit timer/counter0 with pwm timer/counter0 is a general purpose, single channel, 8-bit timer/counter module. the main features are: ? single channel counter ? clear timer on compar e match (auto reload) ? glitch-free, phase correct pu lse width modulator (pwm) ? frequency generator ? external event counter ? 10-bit clock prescaler ? overflow and compare match interrupt sources (tov0 and ocf0) overview a simplified block diagram of the 8-bit timer/counter is shown in figure 33 . for the actual place- ment of i/o pins, refer to ?pinout atmega162? on page 2 . cpu accessible i/o registers, including i/o bits and i/o pins, are shown in bold. the device-specific i/o register and bit loca- tions are listed in the ?8-bit timer/counter register description? on page 100 . figure 33. 8-bit timer/counter block diagram registers the timer/counter (tcnt0) and output compare register (ocr0) are 8-bit registers. interrupt request (abbreviated to int.req. in the figure) si gnals are all visible in the timer interrupt flag register (tifr). all interrupts are individually masked with the timer interrupt mask register (timsk). tifr and timsk are not shown in the figure since these registers are shared by other timer units. the timer/counter can be clocked internally, via the prescaler, or by an external clock source on the t0 pin. the clock select logic block controls which clock source and edge the timer/counter uses to increment (or decrement) its value. the timer/counter is inactive when no clock source is selected. the output from the clock select logic is referred to as the timer clock (clk t 0). timer/counter data b u s = tcntn waveform generation ocn = 0 control logic = 0xff bottom count clear direction tovn (int.req.) ocrn tccrn clock select tn edge detector ( from prescaler ) clk tn top ocn (int.req.) 90 2513k?avr?07/09 atmega162/v the double buffered output compare register (ocr0) is compared with the timer/counter value at all times. the result of the compare can be used by the waveform generator to gener- ate a pwm or variable frequency output on the output compare pin (oc0). see ?output compare unit? on page 91. for details. the comp are match event will also set the compare flag (ocf0) which can be used to generate an output compare interrupt request. definitions many register and bit references in this section are written in general form. a lower case ?n? replaces the timer/counter number, in this case 0. however, when using the register or bit defines in a program, the precise form must be used i.e., tcnt0 for accessing timer/counter0 counter value and so on. the definitions in table 46 are also used extensively throughout the document. timer/counter clock sources the timer/counter can be clocked by an internal or an external clock source. the clock source is selected by the clock select logic which is controlled by the clock select (cs02:0) bits located in the timer/counter control register (tccr0). for details on clock sources and pres- caler, see ?timer/counter0, timer/counter1, and timer/counter3 prescalers? on page 104 . table 46. definitions bottom the counter reaches the bottom when it becomes 0x00. max the counter reaches its maximum when it becomes 0xff (decimal 255). top the counter reaches the top when it becomes equal to the highest value in the count sequence. the top value can be assigned to be the fixed value 0xff (max) or the value stored in the ocr0 register. the assignment is dependent on the mode of operation. 91 2513k?avr?07/09 atmega162/v counter unit the main part of the 8-bit timer/counter is the programmable bi-directional counter unit. figure 34 shows a block diagram of the counter and its surroundings. figure 34. counter unit block diagram signal description (internal signals): count increment or decrement tcnt0 by 1. direction select between increment and decrement. clear clear tcnt0 (set a ll bits to zero). clk t n timer/counter clock, referred to as clk t0 in the following. top signalize that tcnt0 has reached maximum value. bottom signalize that tcnt0 has re ached minimum value (zero). depending of the mode of operation used, the counter is cleared, incremented, or decremented at each timer clock (clk t 0). clk t 0 can be generated from an external or internal clock source, selected by the clock select bits (cs02:0). when no clock source is selected (cs02:0 = 0) the timer is stopped. however, the tcnt0 value can be accessed by the cpu, regardless of whether clk t 0 is present or not. a cpu write override s (has priority over) all counter clear or count operations. the counting sequence is determined by the setting of the wgm01 and wgm00 bits located in the timer/counter control register (tccr0). there are close connections between how the counter behaves (counts) and how waveforms are generated on the output compare output oc0. for more details about advanced counting sequences and waveform generation, see ?modes of operation? on page 94 . the timer/counter overflow (tov0) flag is set according to the mode of operation selected by the wgm01:0 bits. tov0 can be used for generating a cpu interrupt. output compare unit the 8-bit comparator continuously compares tcnt0 with the output compare register (ocr0). whenever tcnt0 equals ocr0, the comparator signals a match. a match will set the output compare flag (ocf0) at the next timer clock cycle. if enabled (ocie0 = 1 and global interrupt flag in sreg is set), the output compare flag generates an output compare interrupt. the ocf0 flag is automatically cleared when th e interrupt is executed. alternatively, the ocf0 flag can be cleared by software by writing a logical one to its i/o bit location. the waveform gen- erator uses the match signal to generate an output according to operating mode set by the wgm01:0 bits and compare output mode (com01:0) bits. the max and bottom signals are used by the waveform generator for handling the special cases of the extreme values in some modes of operation ( see ?modes of operation? on page 94. ). figure 35 shows a block diagram of the output compare unit. data b u s tcntn control logic count tovn (int.req.) clock select top tn edge detector ( from prescaler ) clk tn bottom direction clear 92 2513k?avr?07/09 atmega162/v figure 35. output compare unit, block diagram the ocr0 register is double buffered when us ing any of the pulse width modulation (pwm) modes. for the normal and clear timer on compare (ctc) modes of operation, the double buffering is disabled. the double buffering synchronizes the update of the ocr0 compare reg- ister to either top or bottom of the counting sequence. the synchronization prevents the occurrence of odd-length, non-symmetrical pwm pulses, thereby making the output glitch-free. the ocr0 register access may seem complex, but this is not case. when the double buffering is enabled, the cpu has access to the ocr0 buff er register, and if double buffering is disabled the cpu will access the ocr0 directly. force output compare in non-pwm waveform generation modes, the match output of the comparator can be forced by writing a one to the force output compare (foc0) bit. forcing compare match will not set the ocf0 flag or reload/clear the timer, but the oc0 pin will be updated as if a real compare match had occurred (the com01:0 bits settings define whether the oc0 pin is set, cleared or toggled). compare match blocking by tcnt0 write all cpu write operations to the tcnt0 register will block any compare ma tch that occur in the next timer clock cycle, even when the timer is st opped. this feature allows ocr0 to be initialized to the same value as tcnt0 without triggering an interrupt when the timer/counter clock is enabled. ocfn (int.req.) = (8-bit comparator ) ocrn ocn data b u s tcntn wgmn1:0 waveform generator top focn comn1:0 bottom 93 2513k?avr?07/09 atmega162/v using the output compare unit since writing tcnt0 in any mode of operation will block all comp are matches for one timer clock cycle, there are risks involved when changi ng tcnt0 when using the output compare channel, independently of whether the timer/counter is running or not. if the value written to tcnt0 equals the ocr0 value, the compare match will be missed, resulting in incorrect waveform gen- eration. similarly, do not write the tcnt0 value equal to bottom when the counter is down- counting. the setup of the oc0 should be performed before setting the data direction register for the port pin to output. the easiest way of setting the oc0 value is to use the force output compare (foc0) strobe bits in normal mode. the oc 0 register keeps its value even when changing between waveform generation modes. be aware that the com01:0 bits are not double buffered together with the compare value. changing the com01:0 bits will take effect immediately. compare match output unit the compare output mode (com01:0) bits hav e two functions. the waveform generator uses the com01:0 bits for defining the output compare (oc0) state at the next compare match. also, the com01:0 bits control the oc0 pin output source. figure 36 shows a simplified sche- matic of the logic affected by the com01:0 bit setting. the i/o registers, i/o bits, and i/o pins in the figure are shown in bold. only the parts of the general i/o port control registers (ddr and port) that are affected by the com01:0 bits are shown. when referring to the oc0 state, the reference is for the internal oc0 register, not the oc0 pin. if a system reset occur, the oc0 register is reset to ?0?. figure 36. compare match output unit, schematics the general i/o port function is overridden by the output compare (oc0) from the waveform generator if either of the com01:0 bits are set. however, the oc0 pin direction (input or output) is still controlled by the data direction register (ddr) for the port pin. the data direction regis- ter bit for the oc0 pin (ddr_oc0) must be set as output before the oc0 value is visible on the pin. the port override function is independent of the waveform generation mode. port ddr dq dq ocn pin ocn dq waveform generator comn1 comn0 0 1 data b u s focn clk i/o 94 2513k?avr?07/09 atmega162/v the design of the output compare pin logic allows initialization of the oc0 state before the out- put is enabled. note that some com01:0 bit settings are reserved for certain modes of operation. see ?8-bit timer/counter register description? on page 100. compare output mode and waveform generation the waveform generator uses the com01:0 bits differently in normal, ctc, and pwm modes. for all modes, setting the com01:0 = 0 tells the waveform generator that no action on the oc0 register is to be performed on the next compare match. for compare output actions in the non-pwm modes refer to table 48 on page 101 . for fast pwm mode, refer to table 49 on page 101 , and for phase correct pwm refer to table 50 on page 101 . a change of the com01:0 bits stat e will have effect at the first co mpare match after the bits are written. for non-pwm modes, the action can be fo rced to have immediate effect by using the foc0 strobe bits. modes of operation the mode of operation, i.e., the behavior of the timer/counter and the output compare pins, is defined by the combination of the waveform generation mode (wgm01:0) and compare output mode (com01:0) bits. the compare output mode bits do not affect the counting sequence, while the waveform generation mode bits do. the com01:0 bits control whether the pwm out- put generated should be inverted or not (inverted or non-inverted pwm). for non-pwm modes the com01:0 bits control whether the output should be set, cleared, or toggled at a compare match ( see ?compare match output unit? on page 93. ). for detailed timing information refer to figure 40 , figure 41 , figure 42 and figure 43 in ?timer/counter timing diagrams? on page 98 . normal mode the simplest mode of operation is the normal mode (wgm01:0 = 0). in this mode the counting direction is always up (incrementing), and no counter clear is performed. the counter simply overruns when it passes its maximum 8-bit value (top = 0xff) and then restarts from the bot- tom (0x00). in normal o peration the timer/counter overflow flag (tov0) will be set in the same timer clock cycle as the tcnt0 becomes zero. the tov0 flag in this case behaves like a ninth bit, except that it is only set, not cleared. however, combined with the timer overflow interrupt that automatically clears the tov0 flag, the timer resolution can be increased by software. there are no special cases to consider in the normal mode, a new counter value can be written anytime. the output compare unit can be used to generate interrupts at some given time. using the out- put compare to generate waveforms in normal mo de is not recommended, since this will occupy too much of the cpu time. clear timer on compare match (ctc) mode in clear timer on compare or ctc mode (wgm01:0 = 2), the ocr0 register is used to manip- ulate the counter resolution. in ctc mode the counter is cleared to zero when the counter value (tcnt0) matches the ocr0. the ocr0 defines the top value for the counter, hence also its resolution. this mode allows greater control of the compare match output frequency. it also sim- plifies the operation of counting external events. the timing diagram for the ctc mode is shown in figure 37 . the counter value (tcnt0) increases until a compare match occurs between tcnt0 and ocr0, and then counter (tcnt0) is cleared. 95 2513k?avr?07/09 atmega162/v figure 37. ctc mode, timing diagram an interrupt can be generated each time the counter value reaches the top value by using the ocf0 flag. if the interrupt is enabled, the interrupt handler routine can be used for updating the top value. however, changing top to a value close to bottom when the counter is running with none or a low prescaler value must be done with care since the ctc mode does not have the double buffering feature. if the new value written to ocr0 is lower than the current value of tcnt0, the counter will miss the compare match. the counter will then have to count to its max- imum value (0xff) and wrap around starting at 0x00 before the compare match can occur. for generating a waveform output in ctc mode, the oc0 output can be set to toggle its logical level on each compare match by setting the compare output mode bits to toggle bitmode (com01:0 = 1). the oc0 value will no t be visible on the port pin unl ess the data direction for the pin is set to output. the waveform g enerated will have a maximum frequency of f oc 0 = f clk_i/o /2 when ocr0 is set to zero (0x00). the waveform frequency is defined by the following equation: the n variable represents the prescale factor (1, 8, 64, 256, or 1024). as for the normal mode of operation, the tov0 flag is set in the same timer clock cycle that the counter counts from max to 0x00. fast pwm mode the fast pulse width modulation or fast pwm mode (wgm01:0 = 3) provides a high frequency pwm waveform generation option. the fast pwm di ffers from the other pwm option by its sin- gle-slope operation. the counter counts from bottom to max then restarts from bottom. in non-inverting compare output mode, the output compare (oc0) is cleared on the compare match between tcnt0 and ocr0, and set at bottom. in inverting compare output mode, the output is set on compare match and cleared at bottom. due to the single-slope operation, the operating frequency of the fast pwm mode can be twice as high as the phase correct pwm mode that use dual-slope operation. this high frequency makes the fast pwm mode well suited for power regulation, rectification, and dac app lications. high frequency a llows physically small sized external components (coils, capacitors), and therefore reduces total system cost. in fast pwm mode, the counter is incremented until the counter value matches the max value. the counter is then cleared at the following timer clock cycle. the timing diagram for the fast pwm mode is shown in figure 38 . the tcnt0 value is in the timing diagram shown as a histo- gram for illustrating the single-s lope operation. the diagram includes non- inverted and inverted pwm outputs. the small horizontal line ma rks on the tcnt0 slopes represent compare matches between ocr0 and tcnt0. tcntn ocn (toggle) ocn interrupt flag set 1 4 period 2 3 (comn1:0 = 1) f ocn f clk_i/o 2 n 1 ocrn + () ?? ---------------------------------------------- - = 96 2513k?avr?07/09 atmega162/v figure 38. fast pwm mode, timing diagram the timer/counter overflow flag (tov0) is set each time the counter reaches max. if the inter- rupt is enabled, the interrupt handler routine can be used for updating the compare value. in fast pwm mode, the compare unit allows generation of pwm waveforms on the oc0 pin. set- ting the com01:0 bits to two will produce a non- inverted pwm and an inve rted pwm output can be generated by setting the com01:0 to three (see table 49 on page 101 ). the actual oc0 value will only be visible on the port pin if the data direction for the port pin is set as output. the pwm waveform is generated by setting (or clearing) the oc0 register at the compare match between ocr0 and tcnt0, and clearing (or setting) the oc0 register at the timer clock cycle the counter is cleared (changes from max to bottom). the pwm frequency for the output can be calculated by the following equation: the n variable represents the prescale factor (1, 8, 64, 256, or 1024). the extreme values for the ocr0 register represents special cases when generating a pwm waveform output in the fast pwm mode. if the ocr0 is set equal to bottom, the output will be a narrow spike for each max+1 ti mer clock cycle. setting the ocr0 equal to max will result in a constantly high or low output (depending on the polarity of the output set by the com01:0 bits.) a frequency (with 50% duty cycle) waveform output in fast pwm mode can be achieved by set- ting oc0 to toggle its logical level on each compare match (com01:0 = 1). the waveform generated will have a ma ximum frequency of f oc 0 = f clk_i/o /2 when ocr0 is set to zero. this fea- ture is similar to the oc0 toggle in ctc mode, except the double buffer feature of the output compare unit is enabled in the fast pwm mode. phase correct pwm mode the phase correct pwm mode (wgm01:0 = 1) pr ovides a high resolution phase correct pwm waveform generation option. the phase correct pwm mode is based on a dual-slope operation. the counter counts repeatedly from bottom to max and then from max to bottom. in non- inverting compare output mode, the output compare (oc0) is cleared on the compare match between tcnt0 and ocr0 while up-counting, and set on the compare match while down- counting. in inverting output compare mode, the operation is inverted. the dual-slope operation tcntn ocrn update ans tovn interrupt flag set 1 period 2 3 ocn ocn (comn1:0 = 2) (comn1:0 = 3) ocrn interrupt flag set 4 5 6 7 f ocnpwm f clk_i/o n 256 ? ------------------ = 97 2513k?avr?07/09 atmega162/v has lower maximum operation frequency than single slope operation. however, due to the sym- metric feature of the dual-slope pwm modes, these modes are preferred for motor control applications. the pwm resolution for the phase correct pwm m ode is fixed to eight bits. in phase correct pwm mode the counter is incremented until the counter value matches max. when the counter reaches max, it changes the count direction. the tcnt0 value will be equal to max for one timer clock cycle. the timing diagram fo r the phase correct pwm mode is shown on figure 39 . the tcnt0 value is in the timing diagram shown as a histogram for illustrating the dual-slope operation. the diagram includes non-inverted and inverted pwm outputs. the small horizontal line marks on the tcnt0 slopes represent compare matches between ocr0 and tcnt0. figure 39. phase correct pwm mode, timing diagram the timer/counter overflow flag (tov0) is set each time the counter reaches bottom. the interrupt flag can be used to generate an interrupt each time the counter reaches the bottom value. in phase correct pwm mode, the compare unit allows generation of pwm waveforms on the oc0 pin. setting the com01:0 bits to two will produce a non-inverted pwm. an inverted pwm output can be generated by setting the com01:0 to three (see table 50 on page 101 ). the actual oc0 value will only be visibl e on the port pin if the data direction for the port pin is set as output. the pwm waveform is generated by clearing (or setting) the oc0 register at the com- pare match between ocr0 and tcnt0 when the counter increments, and setting (or clearing) the oc0 register at compare match between ocr0 and tcnt0 when the counter decrements. the pwm frequency for the output when using phase correct pwm can be calculated by the fol- lowing equation: the n variable represents the prescale factor (1, 8, 64, 256, or 1024). tovn interrupt flag set ocn interrupt flag set 1 2 3 tcntn period ocn ocn (comn1:0 = 2) (comn1:0 = 3) ocrn update f ocnpcpwm f clk_i/o n 510 ? ------------------ = 98 2513k?avr?07/09 atmega162/v the extreme values for the ocr0 register represent special cases when generating a pwm waveform output in the phase correct pwm mode. if the ocr0 is set equal to bottom, the out- put will be continuously low and if set equal to max the output will be continuously high for non- inverted pwm mode. for inverted pwm the output will have the opposite logic values. at the very start of period 2 in figure 39 ocn has a transition from high to low even though there is no compare match. the point of this transition is to guarantee symmetry around bottom. there are two cases that give a transition without compare match. ? ocr0 changes its value from max, like in figure 39 . when the ocr0 value is max the ocn pin value is the same as the result of a down-counting compare match. to ensure symmetry around bottom the ocn value at max must correspond to the result of an up- counting compare match. ? the timer starts counting from a value higher than the one in ocr0, and for that reason misses the compare match and hence the ocn change that would have happened on the way up. timer/counter timing diagrams the timer/counter is a synchronous design and the timer clock (clk t 0) is therefore shown as a clock enable signal in the following figures. the figures include information on when interrupt flags are set. figure 40 contains timing data for basic timer/counter operation. the figure shows the count sequence close to the max val ue in all modes other than phase correct pwm mode. figure 40. timer/counter timing diagram, no prescaling figure 41 shows the same timing data, but with the prescaler enabled. figure 41. timer/counter timing diagram, with prescaler (f clk_i/o /8) figure 42 shows the setting of ocf0 in all modes except ctc mode. clk tn (clk i/o /1) tovn clk i/o tcntn max - 1 max bottom bottom + 1 tovn tcntn max - 1 max bottom bottom + 1 clk i/o clk tn (clk i/o /8) 99 2513k?avr?07/09 atmega162/v figure 42. timer/counter timing diagram, setting of ocf0, with prescaler (f clk_i/o /8) figure 43 shows the setting of ocf0 and the clearing of tcnt0 in ctc mode. figure 43. timer/counter timing diagram, clear ti mer on compare match mode, with pres- caler (f clk_i/o /8) ocfn ocrn tcntn ocrn value ocrn - 1 ocrn ocrn + 1 ocrn + 2 clk i/o clk tn (clk i/o /8) ocfn ocrn tcntn (ctc) top top - 1 top bottom bottom + 1 clk i/o clk tn (clk i/o /8) 100 2513k?avr?07/09 atmega162/v 8-bit timer/counter register description timer/counter control register ? tccr0 ? bit 7 ? foc0: force output compare the foc0 bit is only active when the wgm00 bit specifies a non-pwm mode. however, for ensuring compatibility with future devices, this bit must be set to zero when tccr0 is written when operating in pwm mode. when writing a logical one to the foc0 bit, an immediate com- pare match is forced on the waveform generation unit. the oc0 output is changed according to its com01:0 bits setting. note that the foc0 bi t is implemented as a strobe. therefore it is the value present in the com01:0 bits that determines the effect of the forced compare. a foc0 strobe will not generate any interrupt, nor will it clear the timer in ctc mode using ocr0 as top. the foc0 bit is always read as zero. ? bit 6, 3 ? wgm01:0: waveform generation mode these bits control the counting sequence of the counter, the source for the maximum (top) counter value, and what type of waveform generation to be used. modes of operation supported by the timer/counter unit are: normal mode, clear timer on compare match (ctc) mode, and two types of pulse width modulation (pwm) modes. see table 47 and ?modes of operation? on page 94 . note: 1. the ctc0 and pwm0 bit definition names are now obsolete. use the wgm01:0 definitions. however, the functionality and location of these bits are compatible with previous versions of the timer. ? bit 5:4 ? com01:0: compare match output mode these bits control the output compare pin (oc0) behavior. if one or both of the com01:0 bits are set, the oc0 output overrides the normal port functionality of the i/o pin it is connected to. however, note that the data direction register (ddr) bit corresponding to the oc0 pin must be set in order to enable the output driver. bit 76543210 foc0 wgm00 com01 com00 wgm01 cs02 cs01 cs00 tccr0 read/write w r/w r/w r/w r/w r/w r/w r/w initial value 0 0 0 0 0 0 0 0 table 47. waveform generation mode bit description (1) mode wgm01 (ctc0) wgm00 (pwm0) timer/counter mode of operation top update of ocr0 at tov0 flag set on 0 0 0 normal 0xff immediate max 1 0 1 pwm, phase correct 0xff top bottom 2 1 0 ctc ocr0 immediate max 3 1 1 fast pwm 0xff top max 101 2513k?avr?07/09 atmega162/v when oc0 is connected to the pin, the function of the com01:0 bits depends on the wgm01:0 bit setting. table 48 shows the com01:0 bit functionality when the wgm01:0 bits are set to a normal or ctc mode (non-pwm). table 49 shows the com01:0 bit functionality when the wgm01:0 bits are set to fast pwm mode. note: 1. a special case occurs when ocr0 equals to p and com01 is set. in this case, the compare match is ignored, but the set or clear is done at top. see ?fast pwm mode? on page 95 for more details. table 50 shows the com01:0 bit functionality when the wgm01:0 bits are set to phase correct pwm mode. note: 1. a special case occurs when ocr0 equals to p and com01 is set. in this case, the compare match is ignored, but the set or clear is done at top. see ?phase correct pwm mode? on page 96 for more details. table 48. compare output mode, non-pwm mode com01 com00 description 0 0 normal port operation, oc0 disconnected. 0 1 toggle oc0 on compare match. 1 0 clear oc0 on compare match. 1 1 set oc0 on compare match. table 49. compare output mode, fast pwm mode (1) com01 com00 description 0 0 normal port operation, oc0 disconnected. 01reserved 1 0 clear oc0 on compare match, set oc0 at top. 1 1 set oc0 on compare match, clear oc0 at top. table 50. compare output mode, phase correct pwm mode (1) com01 com00 description 0 0 normal port operation, oc0 disconnected. 01reserved 1 0 clear oc0 on compare match when up-counting. set oc0 on compare match when down-counting. 1 1 set oc0 on compare match when up-counting. clear oc0 on compare match when down-counting. 102 2513k?avr?07/09 atmega162/v ? bit 2:0 ? cs02:0: clock select the three clock select bits select the clock source to be used by the timer/counter. if external pin modes are used for the timer/counter0, transitions on the t0 pin will clock the counter even if the pin is configured as an output. this feature allows software control of the counting. timer/counter register ? tcnt0 the timer/counter register gives direct ac cess, both for read and write operations, to the timer/counter unit 8-bit counter. writing to the tcnt0 register blocks (removes) the compare match on the following timer clock. modifying the counter (tcnt0) while the counter is running, introduces a risk of missing a compare match between tcnt0 and the ocr0 register. output compare register ? ocr0 the output compare register contains an 8-bit value that is continuously compared with the counter value (tcnt0). a match can be used to generate an output compare interrupt, or to generate a waveform output on the oc0 pin. timer/counter interrupt mask register ? timsk ? bit 1 ? toie0: timer/counter0 overflow interrupt enable when the toie0 bit is written to one, and the i-bit in the status register is set (one), the timer/counter0 overflow interrupt is enabled. the corresponding interrupt is executed if an overflow in timer/counter0 occurs, i.e., when the tov0 bit is set in the timer/counter interrupt flag register ? tifr. table 51. clock select bit description cs02 cs01 cs00 description 0 0 0 no clock source (timer/counter stopped). 001 clk i/o /(no prescaling) 010 clk i/o /8 (from prescaler) 011 clk i/o /64 (from prescaler) 100 clk i/o /256 (from prescaler) 101 clk i/o /1024 (from prescaler) 1 1 0 external clock source on t0 pin. clock on falling edge. 1 1 1 external clock source on t0 pin. clock on rising edge. bit 76543210 tcnt0[7:0] tcnt0 read/write r/w r/w r/w r/w r/w r/w r/w r/w initial value00000000 bit 76543210 ocr0[7:0] ocr0 read/write r/w r/w r/w r/w r/w r/w r/w r/w initial value00000000 bit 76543210 toie1 ocie1a ocie1b ocie2 ticie1 toie2 toie0 ocie0 timsk read/write r/w r/w r/w r/w r/w r/w r/w r/w initial value 0 0 0 0 0 0 0 0 103 2513k?avr?07/09 atmega162/v ? bit 0 ? ocie0: timer/counter0 output compare match interrupt enable when the ocie0 bit is written to one, and the i-bit in the status register is set (one), the timer/counter0 compare match interrupt is enabled. the corresponding interrupt is executed if a compare match in timer/counter0 occurs, i.e., when the ocf0 bit is set in the timer/counter interrupt flag register ? tifr. note: in atmega161 ocie2 and toie2 have switched places in the timsk register. timer/counter interrupt flag register ? tifr ? bit 1 ? tov0: timer/counter0 overflow flag the bit tov0 is set (one) when an overflow occu rs in timer/counter0. tov0 is cleared by hard- ware when executing the corresponding interrupt handling vector. alternatively, tov0 is cleared by writing a logic one to the flag. when the sr eg i-bit, toie0 (timer/counter0 overflow inter- rupt enable), and tov0 are set (one), the timer/ counter0 overflow interrupt is executed. in phase correct pwm mode, this bit is set when timer/counter0 changes counting direction at 0x00. ? bit 0 ? ocf0: output compare flag 0 the ocf0 bit is set (one) when a compare match occurs between the timer/counter0 and the data in ocr0 ? output compare register0. ocf0 is cleared by hardware when executing the corresponding interrupt handling vector. alternativ ely, ocf0 is cleared by writing a logic one to the flag. when the i-bit in sreg, ocie0 (timer/counter0 compare match interrupt enable), and ocf0 are set (one), the timer/counter0 compare match interrupt is executed. note: in atmega161 ocf2 and tov2 have switched places in the tifr register. bit 76543210 tov1 ocf1a ocf1b ocf2 icf1 tov2 tov0 ocf0 tifr read/write r/w r/w r/w r/w r/w r/w r/w r/w initial value00000000 104 2513k?avr?07/09 atmega162/v timer/counter0, timer/counter1, and timer/counter3 prescalers timer/counter3, timer/counter1, and timer/c ounter0 share the same prescaler module, but the timer/counters can have different prescaler settings. the description below applies to timer/counter3, timer/counter1, and timer/counter0. internal clock source the timer/counter can be clocked directly by the system clock (by setting the csn2:0 = 1). this provides the fastest operation, with a maximum timer/counter clock frequency equal to system clock frequency (f clk_i/o ). alternatively, one of four taps from the prescaler can be used as a clock source. the prescaled clock has a frequency of either f clk_i/o /8, f clk_i/o /64, f clk_i/o /256, or f clk_i/o /1024. in addition, timer/counter3 has the option of choosing f clk_i/o /16 and f clk_i/o /32. prescaler reset the prescaler is free running, i.e., operates independently of the clock select logic of the timer/counter, and it is shared by timer/counter3, timer/counter1, and timer/counter0. since the prescaler is not affected by the timer/counter?s clock select , the state of the prescaler will have implications for situations where a prescal ed clock is used. one example of prescaling arti- facts occurs when the timer is enabled and clocked by the prescaler (6 > csn2:0 > 1). the number of system clock cycles from when the timer is enabled to the fi rst count occurs can be from 1 to n+1 system clock cycles, where n equals the prescaler divisor (8, 64, 256, or 1024, additional selections for timer/counter3: 32 and 64). it is possible to use the prescaler reset for synchronizing the timer/counter to program execu- tion. however, care must be taken if the other timer/counter that shares the same prescaler also uses prescaling. a prescaler reset will affe ct the prescaler period for all timer/counters it is connected to. external clock source an external clock source applied to the tn/t0 pin can be used as timer/counter clock (clk t1 /clk t 0) for timer/counter1 and timer/counter0. the tn/t0 pin is sampled once every sys- tem clock cycle by the pin synchronization lo gic. the synchronized (s ampled) signal is then passed through the edge detector. figure 44 shows a functional equivalent block diagram of the tn/t0 synchronization and edge detector logic. the registers are clocked at the positive edge of the internal system clock ( clk i/o ). the latch is transparent in the high period of the internal system clock. the edge detector generates one clk t1 /clk t 0 pulse for each positive (csn2:0 = 7) or negative (csn2:0 = 6) edge it detects. figure 44. tn/t0 pin sampling the synchronization and e dge detector logic introduces a de lay of 2.5 to 3.5 system clock cycles from an edge has been applied to the tn/t0 pin to the counter is updated. enabling and disabling of the clock input must be done when tn/t0 has been stable for at least one system clock cycle, otherwise it is a risk t hat a false timer/counter clock pulse is generated. tn_sync (to clock select logic) edge detector synchronization dq dq le dq tn clk i/o 105 2513k?avr?07/09 atmega162/v each half period of the external clock applie d must be longer than one system clock cycle to ensure correct sampling. the external clock must be guaranteed to have less than half the sys- tem clock frequency (f extclk < f clk_i/o /2) given a 50/50% duty cycle. since the edge detector uses sampling, the maximum frequency of an external clock it can detect is half the sampling fre- quency (nyquist sampling theorem). however, due to variation of the system clock frequency and duty cycle caused by oscillator source (crystal, resonator, and capacitors) tolerances, it is recommended that maximum frequency of an external clock source is less than f clk_i/o /2.5. an external clock source can not be prescaled. figure 45. prescaler for timer/counter0, timer/counter1, and timer/counter3 (1) note: 1. the synchronization logic on the input pins ( tn/t0) is shown in figure 44 . special function io register ? sfior ? bit 7 ? tsm: timer/counter synchronization mode writing the tsm bit to one activates the timer/counter synchronization mode. in this mode, the value that is written to the psr2 and psr 310 bits is kept, hence keeping the corresponding prescaler reset signals asserted. this ensures th at the corresponding timer/counters are halted and can be configured to the same value withou t the risk of one of them advancing during con- figuration. when the tsm bit is written to zero, the psr2 and psr310 bits are cleared by hardware, and the timer/counters start counting simultaneously. ? bit 0 ? psr310: prescaler reset timer/counter3, timer/counter1, and timer/counter0 when this bit is one, the time r/counter3, timer/counter1, an d timer/counter0 prescaler will be reset. this bit is normally cleared immediately by hardware, except if the tsm bit is set. note that timer/counter3, timer/counter1, and timer/counter0 share the same prescaler and a reset of this prescaler will affect all three timers. psr321 clear clk t1 timer/counter1 clock source 0 cs10 cs11 cs12 t1 clk t0 timer/counter1 clock source 0 cs00 cs01 cs02 t0 clk t3 timer/counter3 clock source 0 cs30 cs31 cs32 10-bit t/c prescaler ck ck/8 ck/64 ck/256 ck/1024 ck/16 ck/32 bit 7 6 5 4 3 2 1 0 tsm xmbk xmm2 xmm1 xmm0 pud psr2 psr310 sfior read/write r/w r/w r/w r/w r/w r/w r/w r/w initial value 0 0 0 0 0 0 0 0 106 2513k?avr?07/09 atmega162/v 16-bit timer/counter (timer/counter 1 and timer/counter3 ) the 16-bit timer/counter unit allows accurate program execution timing (event management), wave generation, and signal timing measurement. the main features are: ? true 16-bit design (i.e., allows 16-bit pwm) ? two independent output compare units ? double buffered out put compare registers ? one input capture unit ? input capture noise canceler ? clear timer on compar e match (auto reload) ? glitch-free, phase correct pu lse width modulator (pwm) ? variable pwm period ? frequency generator ? external event counter ? eight independent interrupt sources (tov1, ocf1a, ocf1b, icf1, tov3, ocf3a, ocf3b, and icf3) restriction in atmega161 compatibility mode note that in atmega161 compatibility mode, only one 16-bits timer/counter is available (timer/counter1). overview most register and bit references in this sect ion are written in general form. a lower case ?n? replaces the timer/counter number, and a lower case ?x? replaces the output compare unit channel. however, when using the register or bit defines in a program, the precise form must be used i.e., tcnt1 for accessing timer/counter1 counter value and so on. a simplified block diagram of the 16-bit timer/counter is shown in figure 46 . for the actual placement of i/o pins, refer to ?pinout atmega162? on page 2 . cpu accessible i/o registers, including i/o bits and i/o pins, are shown in bold. the device-specific i/o register and bit loca- tions are listed in the ?16-bit timer/counter register description? on page 128 . 107 2513k?avr?07/09 atmega162/v figure 46. 16-bit timer/counter block diagram (1) note: 1. refer to figure 1 on page 2 , table 32 on page 72 , and table 38 on page 78 for timer/counter1 pin placement and description. registers the timer/counter (tcntn), output compare registers (ocrna/b), and input capture regis- ter (icrn) are all 16-bit registers. special procedures must be followed when accessing the 16- bit registers. these procedures are described in the section ?accessing 16-bit registers? on page 109 . the timer/counter co ntrol registers (tccrna/b) are 8-bit registers and have no cpu access restrictions. interrupt requests (abbrevi ated to int.req. in the figure) signals are all visible in the timer interrupt flag register (tifr) and extended timer interrupt flag register (etifr). all interrupts are individually masked with the timer interrupt mask register (timsk) and extended timer interrupt mask register (etimsk). (e)tifr and (e)timsk are not shown in the figure since these registers are shared by other timer units. the timer/counter can be clocked internally, via the prescaler, or by an external clock source on the t1 pin. the clock select logic block controls which clock source and edge the timer/counter uses to increment (or decrement) its value. the timer/counter is inactive when no clock source is selected. the output from the clock select logic is refe rred to as the timer clock (clk t n ). the double buffered output compare registers (ocrna/b) are compared with the timer/coun- ter value at all time. the result of the compare can be used by the waveform generator to generate a pwm or variable frequency output on the output compare pin (ocna/b). see ?out- put compare units? on page 114. the compare match event will also set the compare match flag (ocfna/b) which can be used to generate an output compare interrupt request. clock select timer/counter databus ocrna ocrnb icrn = = tcntn waveform generation waveform generation ocna ocnb noise canceler icpn = fixed top values edge detector control logic = 0 top bottom count clear direction tovn (int.req.) ocna (int.req.) ocnb (int.req.) icfn (int.req.) tccrna tccrnb ( from analog comparator ouput ) tn edge detector ( from prescaler ) clk tn 108 2513k?avr?07/09 atmega162/v the input capture register can capture the timer/ counter value at a given external (edge trig- gered) event on either the input capture pin (icpn) or on the analog comparator pins ( see ?analog comparator? on page 195. ) the input capture unit includes a digital filtering unit (noise canceler) for reducing the chance of capturing noise spikes. the top value, or maximum timer/counter value, can in some modes of operation be defined by either the ocrna register, the icrn regist er, or by a set of fixed values. when using ocrna as top value in a pwm mode, the ocrna register can not be used for generating a pwm output. however, the top value will in this case be do uble buffered allowing the top value to be changed in run time. if a fixed top value is required, the icrn register can be used as an alternative, freeing the ocrna to be used as pwm output. definitions the following definitions are used extensively throughout the section: compatibility the 16-bit timer/counter has been updated and impr oved from previous versions of the 16-bit avr timer/counter. this 16-bit timer/counter is fully compatible with the earlier version regarding: ? all 16-bit timer/counter related i/o register address locations, including timer interrupt registers. ? bit locations inside all 16-bit timer/counter registers, including timer interrupt registers. ? interrupt vectors. the following control bits have changed name, but have same functionality and register location: ? pwmn0 is changed to wgmn0. ? pwmn1 is changed to wgmn1. ? ctcn is changed to wgmn2. the following bits are added to the 16-bit timer/counter control registers: ? focna and focnb are added to tccrna. ? wgmn3 is added to tccrnb. the 16-bit timer/counter has improvements that will affect the compatibility in some special cases. table 52. definitions bottom the counter reaches the bottom when it becomes 0x0000. max the counter reaches its max imum when it becomes 0xffff (decimal 65535). top the counter reaches the top when it becomes equal to the highest value in the count sequence. the top value can be assigned to be one of the fixed values: 0x00ff, 0x01ff, or 0x03ff, or to the value stored in the ocrna or icrn register. the assignment is dependent of the mode of operation. 109 2513k?avr?07/09 atmega162/v accessing 16-bit registers the tcntn, ocrna/b, and icrn are 16-bit registers that can be accessed by the avr cpu via the 8-bit data bus. the 16-bit register must be byte accessed using two read or write operations. each 16-bit timer has a single 8-bit register for temporary storing of the high byte of the 16-bit access. the same temporary register is shared between all 16-bit registers within each 16-bit timer. accessing the low byte triggers the 16-bit read or write operation. when the low byte of a 16-bit register is written by the cpu, the high byte stored in the temporary register, and the low byte written are both copied into the 16-bit register in the same clock cycle. when the low byte of a 16-bit register is read by the cpu, the high by te of the 16-bit register is copied into the tempo- rary register in the same clock cycle as the low byte is read. not all 16-bit accesses uses the temporary register for the high byte. reading the ocrna/b 16- bit registers does not involve using the temporary register. to do a 16-bit write, the high byte must be written before the low byte . for a 16-bit read, the low byte must be read before the high byte . the following code examples show how to access the 16-bit timer registers assuming that no interrupts updates the temporary register. the same principle can be used directly for accessing the ocrna/b and icrn registers. note that when using ?c?, the compiler handles the 16-bit access. note: 1. the example code assumes that the pa rt specific header file is included. for i/o registers located in extended i/o map, ?in?, ?out?, ?sbis?, ?s bic?, ?cbi?, and ?sbi? instructions must be replaced with instructions that allow access to extended i/o. typically ?lds? and ?sts? combined with ?sbr s?, ?sbrc?, ?sbr?, and ?cbr?. the assembly code example returns the tcntn value in the r17:r16 register pair. it is important to notice that accessing 16-bit registers are atomic operations. if an interrupt occurs between the two instructions accessing the 16-bit register, and the interrupt code updates the temporary register by accessing the same or any other of the 16-bit timer regis- ters, then the result of the a ccess outside the interrupt will be corrupted. theref ore, when both the main code and the interrupt code update the temporary register, the main code must disable the interrupts during the 16-bit access. assembly code examples (1) ... ; set tcnt n to 0x01ff ldi r17,0x01 ldi r16,0xff out tcnt n h,r17 out tcnt n l,r16 ; read tcnt n into r17:r16 in r16,tcnt n l in r17,tcnt n h ... c code examples (1) unsigned int i; ... /* set tcnt n to 0x01ff */ tcnt n = 0x1ff; /* read tcnt n into i */ i = tcnt n ; ... 110 2513k?avr?07/09 atmega162/v the following code examples show how to do an atomic read of the tcntn register contents. reading any of the ocrna/b or icrn registers can be done by using the same principle. note: 1. the example code assumes that the pa rt specific header file is included. for i/o registers located in extended i/o map, ?in?, ?out?, ?sbis?, ?s bic?, ?cbi?, and ?sbi? instructions must be replaced with instructions that allow access to extended i/o. typically ?lds? and ?sts? combined with ?sbr s?, ?sbrc?, ?sbr?, and ?cbr?. the assembly code example returns the tcntn value in the r17:r16 register pair. assembly code example (1) tim16_readtcnt n : ; save global inter?upt flag in r18,sreg ; disable interrupt? cli ; read tcnt n into r17:r16 in r16,tcnt n l in r17,tcnt n h ; restore global in?errupt flag out sreg,r18 ret c code example (1) unsigned int tim16_readtcnt n ( void ) { unsigned char sreg; unsigned int i; /* save global inte?rupt flag */ sreg = sreg; /* disable interrup?s */ _cli(); /* read tcnt n into i */ i = tcnt n ; /* restore global i?terrupt flag */ sreg = sreg; return i; } 111 2513k?avr?07/09 atmega162/v the following code examples show how to do an atomic write of the tcntn register contents. writing any of the ocrna/b or icrn register s can be done by using the same principle. note: 1. the example code assumes that the pa rt specific header file is included. for i/o registers located in extended i/o map, ?in?, ?out?, ?sbis?, ?s bic?, ?cbi?, and ?sbi? instructions must be replaced with instructions that allow access to extended i/o. typically ?lds? and ?sts? combined with ?sbr s?, ?sbrc?, ?sbr?, and ?cbr?. the assembly code example requires that the r17:r16 register pair contains the value to be writ- ten to tcntn. reusing the temporary high byte register if writing to more than one 16-bit register where the high byte is the same for all registers written, then the high byte only needs to be written once. however, note that the same rule of atomic operation described previously also applies in this case. assembly code example (1) tim16_writetcnt n : ; save global inter?upt flag in r18,sreg ; disable interrupt? cli ; set tcnt n to r17:r16 out tcnt n h,r17 out tcnt n l,r16 ; restore global in?errupt flag out sreg,r18 ret c code example (1) void tim16_writetcnt n ( unsigned int i ) { unsigned char sreg; unsigned int i; /* save global inte?rupt flag */ sreg = sreg; /* disable interrup?s */ _cli(); /* set tcnt n to i */ tcnt n = i; /* restore global i?terrupt flag */ sreg = sreg; } 112 2513k?avr?07/09 atmega162/v timer/counter clock sources the timer/counter can be clocked by an internal or an external clock source. the clock source is selected by the clock select logic which is controlled by the clock select (csn2:0) bits located in the timer/counter control register b (tccrnb). for details on cl ock sources an d prescaler, see ?timer/counter0, timer/counter1, and timer/counter3 prescalers? on page 104 . counter unit the main part of the 16-bit timer/counter is th e programmable 16-bit bi-directional counter unit. figure 47 shows a block diagram of the counter and its surroundings. figure 47. counter unit block diagram signal description (internal signals): count increment or decrement tcntn by 1. direction select between increment and decrement. clear clear tcntn (set a ll bits to zero). clk t n timer/counter clock. top signalize that tcntn has reached maximum value. bottom signalize that tcntn has re ached minimum value (zero). the 16-bit counter is mapped into two 8-bit i/o memory locations: counter high (tcntnh) con- taining the upper eight bits of the counter, and counter low (tcntnl) containing the lower eight bits. the tcntnh register can only be indirect ly accessed by the cpu. when the cpu does an access to the tcntnh i/o location, the cpu accesses the high byte temporary register (temp). the temporary register is updated with the tcntnh value when the tcntnl is read, and tcntnh is updated with the temporary register va lue when tcntnl is written. this allows the cpu to read or write the entire 16-bit counter value within one clock cycle via the 8-bit data bus. it is important to notice that there are special cases of writing to the tcntn register when the counter is counting that will gi ve unpredictable results. the s pecial cases are described in the sections where they are of importance. depending on the mode of operation used, the counter is cleared, incremented, or decremented at each timer clock (clk t n ). the clk t n can be generated from an external or internal clock source, selected by the clock select bits (csn2:0). when no clock source is selected (csn2:0 = 0) the timer is stopped. however, the tcntn value can be accessed by the cpu, independent of whether clk t n is present or not. a cpu write overrides (has priority over) all counter clear or count operations. the counting sequence is determined by the setting of the waveform generation mode bits (wgmn3:0) located in the timer/counter control registers a and b (tccrna and tccrnb). there are close connections between how the counter behaves (counts) and how waveforms are generated on the output compare outputs ocnx. for more details about advanced counting sequences and waveform generation, see ?modes of operation? on page 118 . temp (8-bit) data bus (8-bit) tcntn (16-bit counter) tcntnh (8-bit) tcntnl (8-bit) control logic count clear direction tovn (int.req.) clock select top bottom tn edge detector ( from prescaler ) clk tn 113 2513k?avr?07/09 atmega162/v the timer/counter overflow flag (tovn) is set according to the mode of operation selected by the wgmn3:0 bits. tovn can be used for generating a cpu interrupt. input capture unit the timer/counter incorporates an input capture unit that can capture external events and give them a time-stamp indicating time of occurrence. the external signal indicating an event, or mul- tiple events, can be applied via the icpn pin or alternatively, via the analog comparator unit. the time-stamps can then be used to calculate frequency, duty-cycle, and other features of the signal applied. alternatively the time-stamps can be used for creating a log of the events. the input capture unit is illustrated by the block diagram shown in figure 48 . the elements of the block diagram that are not directly a part of the input capture unit are gray shaded. the small ?n? in register and bit names indicates the timer/counter number. figure 48. input capture unit block diagram (1) note: 1. the analog comparator output (aco) can only trigger the timer/counter1 icp ? not timer/counter3. when a change of the logic level (an event) occurs on the input capture pin (icpn), alternatively on the analog comparator output (aco), and this change confirms to the setting of the edge detector, a capture will be triggered. when a captur e is triggered, the 16-bit value of the counter (tcntn) is written to the input capture register (icrn). the input capture flag (icfn) is set at the same system clock as the tcntn value is c opied into icrn register. if enabled (ticien = 1), the input capture flag generates an input capture interrupt. the icfn flag is automatically cleared when the interrupt is executed. alternatively the icfn flag can be cleared by software by writing a logical one to its i/o bit location. reading the 16-bit value in the input capture register (icrn) is done by first reading the low byte (icrnl) and then the high byte (icrnh). when the low byte is read the high byte is copied into the high byte temporary regi ster (temp). when the cpu reads the icrnh i/o location it will access the temp register. the icrn register can only be written when us ing a waveform generation mode that utilizes the icrn register for defining the counter?s top value. in these cases the waveform genera- icfn (int.req.) analog comparator write icrn (16-bit register) icrnh (8-bit) noise canceler icpn edge detector temp (8-bit) data bus (8-bit) icrnl (8-bit) tcntn (16-bit counter) tcntnh (8-bit) tcntnl (8-bit) acic* icnc ices aco* 114 2513k?avr?07/09 atmega162/v tion mode (wgmn3:0) bits must be set before the top value can be written to the icrn register. when writing the icrn re gister the high byte must be written to the icrnh i/o location before the low byte is written to icrnl. for more information on how to access the 16-bit registers refer to ?accessing 16-bit registers? on page 109 . input capture trigger source the main trigger source for the input capture unit is the input capture pin (icpn). timer/counter1 can alternatively use the analog comparator output as trigger source for the input capture unit. the analog comparator is selected as trigger source by setting the analog comparator input capture (acic) bit in the analog comparator control and status register (acsr). be aware that changing trigger source can trigger a capture. the input capture flag must therefore be cleared after the change. both the input capture pin (icpn) and the analog comparator output (aco) inputs are sampled using the same technique as for the tn pin ( figure 44 on page 104 ). the edge detector is also identical. however, when the noise canceler is enabled, additional logic is inserted before the edge detector, which increases t he delay by four system clock cycles. note that the input of the noise canceler and edge detector is always enabl ed unless the timer/counter is set in a wave- form generation mode that uses icrn to define top. an input capture can be trigger ed by software by controlling the port of the icpn pin. noise canceler the noise canceler improves noise immunity by using a simple digital filtering scheme. the noise canceler input is monitored over four samples, and all four must be equal for changing the output that in turn is used by the edge detector. the noise canceler is enabled by setting the input capture noise canceler (icncn) bit in timer/counter control register b (tccrnb). when enabled the noise canceler introduces addi- tional four system clock cycles of delay from a change applied to the input, to the update of the icrn register. the noise canceler uses the sy stem clock and is therefore not affected by the prescaler. using the input capture unit the main challenge when using the input capture unit is to assign enough processor capacity for handling the incoming events. the time between two events is critical. if the processor has not read the captured value in th e icrn register before the nex t event occurs, the icrn will be overwritten with a new value. in this case the result of the ca pture will be incorrect. when using the input capture interrupt, the icrn register should be read as early in the inter- rupt handler routine as possible. even though the input capture interrupt has relatively high priority, the maximum interrupt response time is dependent on the maximum number of clock cycles it takes to handle any of the other interrupt requests. using the input capture unit in any mode of operation when the top value (resolution) is actively changed during operation, is not recommended. measurement of an external signal?s duty cycle requires that the trigger edge is changed after each capture. changing the edge sensing must be done as early as possible after the icrn register has been read. after a change of the edge, the input capture flag (icfn) must be cleared by software (writing a logical one to the i/o bit location). for measuring frequency only, the clearing of the icfn flag is not required (if an interrupt handler is used). output compare units the 16-bit comparator continuously compares tcntn with the output compare register (ocrnx). if tcnt equals ocrnx the comparator signals a match. a match will set the output compare flag (ocfnx) at the next timer clock cycle . if enabled (ocienx = 1), the output com- pare flag generates an output compare interrupt. the ocfnx flag is automatically cleared when the interrupt is executed. alternatively the ocfnx flag can be cleared by software by writ- 115 2513k?avr?07/09 atmega162/v ing a logical one to its i/o bit location. the waveform generator uses the match signal to generate an output according to operating mode set by the waveform generation mode (wgmn3:0) bits and compare output mode (comnx1:0) bits. the top and bottom signals are used by the waveform generator for handling the special cases of the extreme values in some modes of operation ( see ?modes of operation? on page 118. ) a special feature of output compare unit a allows it to define the timer/counter top value (i.e., counter resolution). in addition to the counter resolution, the top value defines the period time for waveforms generated by the waveform generator. figure 49 shows a block diagram of the output compare unit. the small ?n? in the register and bit names indicates the device number (n = n for timer/counter n), and the ?x? indicates output compare unit (a/b). the elements of the block diagr am that are not directly a part of the output compare unit are gray shaded. figure 49. output compare unit, block diagram the ocrnx register is double buffered when using any of the twelve pulse width modulation (pwm) modes. for the normal and clear timer on compare (ctc) modes of operation, the dou- ble buffering is disabled. the double buffering synchronizes the update of the ocrnx compare register to either top or bottom of the counting sequence. the synchronization prevents the occurrence of odd-length, non-symmetrical pwm pulses, thereby making the output glitch-free. the ocrnx register access may seem complex, but this is not case. when the double buffering is enabled, the cpu has access to the ocrnx buffer register, and if double buffering is dis- abled the cpu will access the ocrnx directly. the content of the ocr1x (buffer or compare) register is only changed by a write operation (the timer/counter does not update this register automatically as the tcnt1 and icr1 register). therefore ocr1x is not read via the high byte temporary register (temp). however, it is a good practice to read the low byte first as when accessing other 16-bit registers. writing the ocrnx registers must be done via the temp reg- ister since the compare of all 16 bits is done continuously. the high byte (ocrnxh) has to be written first. when the high byte i/o location is written by the cpu, the temp register will be ocfnx (int.req.) = (16-bit comparator ) ocrnx buffer (16-bit register) ocrnxh buf. (8-bit) ocnx temp (8-bit) data bus (8-bit) ocrnxl buf. (8-bit) tcntn (16-bit counter) tcntnh (8-bit) tcntnl (8-bit) comnx1:0 wgmn3:0 ocrnx (16-bit register) ocrnxh (8-bit) ocrnxl (8-bit) waveform generator top bottom 116 2513k?avr?07/09 atmega162/v updated by the value written. then when the low by te (ocrnxl) is written to the lower eight bits, the high byte will be copied into the upper eight bits of either the ocrnx buffer or ocrnx com- pare register in the same system clock cycle. for more information of how to access the 16-bit registers refer to ?accessing 16-bit registers? on page 109 . force output compare in non-pwm waveform generation modes, the match output of the comparator can be forced by writing a one to the force output compare (focnx) bit. forcing compare match will not set the ocfnx flag or reload/clear the timer, but the ocnx pin will be updated as if a real compare match had occurred (the comn1:0 bits settings define whether the ocnx pin is set, cleared or toggled). compare match blocking by tcntn write all cpu writes to the tcntn register will block an y compare match that occurs in the next timer clock cycle, even when the timer is stopped. this feature allows ocrnx to be initialized to the same value as tcntn without triggering an inte rrupt when the timer/counter clock is enabled. using the output compare unit since writing tcntn in any mode of operation will block all comp are matches for one timer clock cycle, there are risks involved when changing tcntn when using any of the output compare channels, independent of whether the timer/counter is running or not. if the value written to tcntn equals the ocrnx value, t he compare match will be missed, resulting in incorrect wave- form generation. do not write the tcntn equal to top in pwm modes with variable top values. the compare match for the top w ill be ignored and the counter will continue to 0xffff. similarly, do not write the tcntn va lue equal to bottom when the counter is down- counting. the setup of the ocnx should be performed before setting the data direction register for the port pin to output. the easiest way of setting the ocnx value is to use the force output com- pare (focnx) strobe bits in normal mode. the ocnx register keeps its value even when changing between waveform generation modes. be aware that the comnx1:0 bits are not doubl e buffered together with the compare value. changing the comnx1:0 bits will take effect immediately. 117 2513k?avr?07/09 atmega162/v compare match output unit the compare output mode (comnx1:0) bits have two functions. the waveform generator uses the comnx1:0 bits for defining the output compare (ocnx) state at the next compare match. secondly the comnx1:0 bits control the ocnx pin output source. figure 50 shows a simplified schematic of the logic affected by the comnx1:0 bit setting. the i/o registers, i/o bits, and i/o pins in the figure are shown in bold. only the parts of the general i/o port control registers (ddr and port) that are affected by the comnx1:0 bits are shown. when referring to the ocnx state, the reference is for the internal oc nx register, not the ocnx pin. if a system reset occur, the ocnx register is reset to ?0?. figure 50. compare match output unit, schematic the general i/o port function is overridden by the output compare (ocnx) from the waveform generator if either of the comnx1:0 bits are set. however, the ocnx pin direction (input or out- put) is still controlled by the data direction register (ddr) for the port pin. the data direction register bit for the ocnx pin (ddr_ocnx) must be set as output before the ocnx value is visi- ble on the pin. the port override function is generally independent of the waveform generation mode, but there are some exceptions. refer to table 53 , table 54 and table 55 for details. the design of the output compare pin logic allows initialization of the ocnx state before the out- put is enabled. note that some comnx1:0 bi t settings are reserved for certain modes of operation. see ?16-bit timer/counter register description? on page 128. the comnx1:0 bits have no effect on the input capture unit. port ddr dq dq ocnx pin ocnx dq waveform generator comnx1 comnx0 0 1 data b u s focnx clk i/o 118 2513k?avr?07/09 atmega162/v compare output mode and waveform generation the waveform generator uses the comnx1:0 bits differently in normal, ctc, and pwm modes. for all modes, setting the comnx1:0 = 0 tells the waveform generator that no action on the ocnx register is to be performed on the next compare match. for compare output actions in the non-pwm modes refer to table 53 on page 128 . for fast pwm mode refer to table 54 on page 129 , and for phase correct and phase and frequency correct pwm refer to table 55 on page 129 . a change of the comnx1:0 bits state will have effe ct at the first compare match after the bits are written. for non-pwm modes, the action can be fo rced to have immediate effect by using the focnx strobe bits. modes of operation the mode of operation, i.e., the behavior of the timer/counter and the output compare pins, is defined by the combination of the waveform generation mode (wgmn3:0) and compare output mode (comnx1:0) bits. the compare output mode bits do not affect the counting sequence, while the waveform generation mode bits do. the comnx1:0 bits control whether the pwm out- put generated should be inverted or not (inverted or non-inverted pwm). for non-pwm modes the comnx1:0 bits control whether the output should be set, cleared or toggle at a compare match ( see ?compare match output unit? on page 117. ) for detailed timing information refer to ?timer/counter timing diagrams? on page 126 . normal mode the simplest mode of operation is the normal mode (wgmn3:0 = 0). in this mode the counting direction is always up (incrementing), and no counter clear is performed. the counter simply overruns when it passes its maximum 16-bit value (max = 0xffff) and then restarts from the bottom (0x0000). in normal operation the timer/counter overflow flag (tovn) will be set in the same timer clock cycle as the tcntn become s zero. the tovn flag in this case behaves like a 17th bit, except that it is only set, not cleared. however, combined with the timer overflow interrupt that automatically clears the tovn flag, the timer resolution can be increased by soft- ware. there are no special cases to consider in the normal mode, a new counter value can be written anytime. the input capture unit is easy to use in normal mode. however, observe that the maximum interval between the external events must not exceed the resolution of the counter. if the interval between events are too long, the timer overflow interrupt or the prescaler must be used to extend the resolution for the capture unit. the output compare units can be used to generat e interrupts at some given time. using the output compare to gene rate waveforms in norm al mode is not recommended, since this will occupy too much of the cpu time. clear timer on compare match (ctc) mode in clear timer on compare or ctc mode (wgmn3:0 = 4 or 12), the ocrna or icrn register are used to manipulate the counter resolution. in ctc mode the counter is cleared to zero when the counter value (tcntn) matches either the ocrna (wgmn3:0 = 4) or the icrn (wgmn3:0 = 12). the ocrna or icrn define the top value for the counter, hence also its resolution. this mode allows greater control of the compare match output frequency. it also simplifies the oper- ation of counting external events. the timing diagram for the ctc mode is shown in figure 51 . the counter value (tcntn) increases until a compare match occurs with either ocrna or icrn, and then counter (tcntn) is cleared. 119 2513k?avr?07/09 atmega162/v figure 51. ctc mode, timing diagram an interrupt can be generated at each time the counter value reaches the top value by either using the ocfna or icfn flag according to the register used to define the top value. if the interrupt is enabled, the interrupt handler routine can be used for updating the top value. how- ever, changing the top to a value close to bottom when the counter is running with none or a low prescaler value must be done with care since the ctc mode does not have the double buff- ering feature. if the new value written to ocrna or icrn is lower than the current value of tcntn, the counter will miss the compare match. the counter will then have to count to its max- imum value (0xffff) and wrap around starting at 0x0000 before the compare match can occur. in many cases this feature is no t desirable. an alternative will th en be to use the fast pwm mode using ocrna for defining top (w gmn3:0 = 15) since the ocrna then will be doub le buffered. for generating a waveform output in ctc mode, the ocna output can be set to toggle its logical level on each compare match by setting the compare output mode bits to toggle mode (comna1:0 = 1). the ocna value will not be visible on the port pin unless the data direction for the pin is set to output (ddr_ocna = 1). th e waveform generated will have a maximum fre- quency of f oc n a = f clk_i/o /2 when ocrna is set to zero (0x0000). the waveform frequency is defined by the following equation: the n variable represents the prescaler factor (1, 8, 64, 256, or 1024). for timer/counter3 also prescaler factors 16 and 32 are available. as for the normal mode of operation, the tovn flag is set in the same timer clock cycle that the counter counts from max to 0x0000. tcntn ocna (toggle) ocna interrupt flag set or icfn interrupt flag set (interrupt on top) 1 4 period 2 3 (comna1:0 = 1) f ocna f clk_i/o 2 n 1 ocrna + () ?? -------------------------------------------------- - = 120 2513k?avr?07/09 atmega162/v fast pwm mode the fast pulse width modulation or fast pwm mode (wgmn3:0 = 5,6,7,14, or 15) provides a high frequency pwm waveform generation option. the fast pwm differs from the other pwm options by its single-slope operation. the counter counts from bottom to top then restarts from bottom. in non-inverting compare output mode, the output compare (ocnx) is set on the compare match between tcntn and ocrnx, and cleared at top. in inverting compare output mode output is cleared on compare match and set at top. due to the single-slope oper- ation, the operating frequency of the fast pwm mode can be twice as high as the phase correct and phase and frequency correct pwm modes that use dual-slope operation. this high fre- quency makes the fast pwm mode well suited for power regulation, rectification, and dac applications. high frequency allows physically sm all sized external com ponents (coils, capaci- tors), hence reduces total system cost. the pwm resolution for fast pwm can be fixed to 8-, 9-, or 10-bit, or defined by either icrn or ocrna. the minimum resolution allowed is 2-bit (icrn or ocrna set to 0x0003), and the max- imum resolution is 16-bit (icrn or ocrna set to max). the pwm resolution in bits can be calculated by using the following equation: in fast pwm mode the counter is incremented until the counter value matches either one of the fixed values 0x00ff, 0x01ff, or 0x03ff (wgmn3:0 = 5, 6, or 7), the value in icrn (wgmn3:0 = 14), or the value in ocrna (wgmn3:0 = 15). the counter is then cleared at the following timer clock cycle. the timing diagram for the fast pwm mode is shown in figure 52 . the figure shows fast pwm mode when ocrna or icrn is used to define top. the tcntn value is in the timing diagram shown as a histogram for illustrating t he single-slope operation. the diagram includes non-inverted and inverted pwm outputs. the small horizontal line marks on the tcntn slopes represent compare matches between ocrnx and tcntn. the ocnx interrupt flag will be set when a compare match occurs. figure 52. fast pwm mode, timing diagram the timer/counter overflow flag (tovn) is set each time the counter reaches top. in addition the ocna or icfn flag is set at the same time r clock cycle as tovn is set when either ocrna or icrn is used for defining the top value. if one of the interrupts are enabled, the interrupt han- dler routine can be used for updating the top and compare values. when changing the top value the program must ensure that the new top value is higher or equal to the value of all of the compare registers. if the top value is lower than any of the com- r fpwm top 1 + () log 2 () log ---------------------------------- - = tcntn ocrnx / top update and tovn interrupt flag set and ocna interrupt flag set or icfn interrupt flag set (interrupt on top) 1 7 period 2 3 4 5 6 8 ocnx ocnx (comnx1:0 = 2) (comnx1:0 = 3) 121 2513k?avr?07/09 atmega162/v pare registers, a compare ma tch will never occur between the tcntn and the ocrnx. note that when using fixed top values the unused bi ts are masked to zero when any of the ocrnx registers are written. the procedure for updating icrn differs from updating ocrna when used for defining the top value. the icrn register is not double buffered. this means that if icrn is changed to a low value when the counter is running with none or a low prescaler value, there is a risk that the new icrn value written is lower than the current va lue of tcntn. the result will then be that the counter will miss the compare match at the top value. the coun ter will then have to count to the max value (0xffff) and wrap around starting at 0x0000 before the compare match can occur. the ocrna register however, is double buffered. this feature allows the ocrna i/o location to be written anytime. when the ocrna i/o location is written the value written will be put into the ocrna buffer register. the ocrna compare register will then be updated with the value in the buffer register at the next timer clock cycle the tcntn matches top. the update is done at the same timer clock cycle as the tcntn is cleared and the tovn flag is set. using the icrn register for defining top work s well when using fixed top values. by using icrn, the ocrna register is free to be used for generating a pwm output on ocna. however, if the base pwm frequency is actively change d (by changing the top value), using the ocrna as top is clearly a better choice due to its double buffer feature. in fast pwm mode, the compare units allow generation of pwm waveforms on the ocnx pins. setting the comnx1:0 bits to two will produce a non-inverted pwm and an inverted pwm output can be generated by setting the comnx1:0 to three (see table on page 129 ). the actual ocnx value will only be visible on the port pin if the data direction for the port pin is set as output (ddr_ocnx). the pwm waveform is generated by setting (or clearing) the ocnx register at the compare match between ocrnx and tcntn, and clearing (or setting) the ocnx register at the timer clock cycle the counter is cleared (changes from top to bottom). the pwm frequency for the output can be calculated by the following equation: the n variable represents the prescaler divider (1, 8, 64, 256, or 1024). for timer/counter3 also prescaler factors 16 and 32 are available. the extreme values for the ocrnx register represents special cases when generating a pwm waveform output in the fast pwm mode. if the ocrnx is set equal to bottom (0x0000) the out- put will be a narrow spike for eac h top+1 timer clock cycle. se tting the ocrnx equal to top will result in a const ant high or low output (depending on the polarity of the output set by the comnx1:0 bits.) a frequency (with 50% duty cycle) waveform output in fast pwm mode can be achieved by set- ting ocna to toggle its logical level on each compare match (comna1:0 = 1). this applies only if ocrna is used to define the top value (wgm n3:0 = 15). the wave form generated will have a maximum frequency of f oc n a = f clk_i/o /2 when ocrna is set to zero (0x0000). this feature is similar to the ocna toggle in ctc mode, except the double buffer feature of the output compare unit is enabled in the fast pwm mode. f ocnxpwm f clk_i/o n 1 top + () ? ---------------------------------- - = 122 2513k?avr?07/09 atmega162/v phase correct pwm mode the phase correct pulse width modulation or phase correct pwm mode (wgmn3:0 = 1, 2, 3, 10, or 11) provides a high resolution phase correct pwm waveform generation option. the phase correct pwm mode is, like the phase and frequency correct pwm mode, based on a dual- slope operation. the counter counts repeatedly from bottom (0x0000) to top and then from top to bottom. in non-inverting compare output mode, the output compare (ocnx) is cleared on the compare match between tcntn and ocrnx while up-counting, and set on the compare match while down-counting. in inverting output compare mode, the operation is inverted. the dual-slope operation has lower maximum operation frequency than single slope operation. however, due to the symmetric feat ure of the dual-slope pwm modes, these modes are preferred for motor control applications. the pwm resolution for the phase correct pwm mode can be fixed to 8-, 9-, or 10-bit, or defined by either icrn or ocrna. the minimum resolution allowed is 2-bit (icrn or ocrna set to 0x0003), and the maximum resolution is 16-bit (icrn or ocrna set to max). the pwm resolu- tion in bits can be calculated by using the following equation: in phase correct pwm mode the counter is incremented until the counter value matches either one of the fixed values 0x00ff, 0x01ff, or 0x03ff (wgmn3:0 = 1, 2, or 3), the value in icrn (wgmn3:0 = 10), or the value in ocrna (wgmn3:0 = 11). the counter has then reached the top and changes the count direct ion. the tcntn value will be equa l to top for one timer clock cycle. the timing diagram for the ph ase correct pwm mode is shown on figure 53 . the figure shows phase correct pwm mode when ocrna or icrn is used to define top. the tcntn value is in the timing diagram shown as a histogram for illustrati ng the dual-slope operation. the diagram includes non-inverted and inverted pwm outputs. the small horizontal line marks on the tcntn slopes represent compare matches between ocrnx and tcntn. the ocnx inter- rupt flag will be set when a compare match occurs. figure 53. phase correct pwm mode, timing diagram the timer/counter overflow flag (tovn) is set each time the counter reaches bottom. when either ocrna or icrn is used for defining the top value, the ocna or icfn flag is set accord- ingly at the same timer clock cycle as the ocrnx registers are updated with the double buffer r pcpwm top 1 + () log 2 () log ---------------------------------- - = ocrnx/top update and ocna interrupt flag set or icfn interrupt flag set (interrupt on top) 1 2 3 4 tovn interrupt flag set (interrupt on bottom) tcntn period ocnx ocnx (comnx1:0 = 2) (comnx1:0 = 3) 123 2513k?avr?07/09 atmega162/v value (at top). the interrupt flags can be used to generate an interrupt each time the counter reaches the top or bottom value. when changing the top value the program must ensure that the new top value is higher or equal to the value of all of the compare registers. if the top value is lower than any of the com- pare registers, a compare ma tch will never occur between the tcntn and the ocrnx. note that when using fixed top values, the unused bits are masked to zero when any of the ocrnx registers are written. as the third period shown in figure 53 illustrates, changing the top actively while the timer/counter is running in the phase correct mode can result in an unsym- metrical output. the reason for this can be found in the time of update of the ocrnx register. since the ocrnx update occurs at top, the pwm period starts and ends at top. this implies that the length of the falling slope is determined by the previous top value, while the length of the rising slope is determined by the new to p value. when these two values differ the two slopes of the period will differ in length. the di fference in length gives the unsymmetrical result on the output. it is recommended to use the phase and frequency correct mode instead of the phase correct mode when changing the top value while the timer/counter is running. when using a static top value there are practically no differences between the two modes of operation. in phase correct pwm mode, the compare units allow generation of pwm waveforms on the ocnx pins. setting the comnx1:0 bits to tw o will produce a non-inverte d pwm and an inverted pwm output can be generated by setting the comnx1:0 to three (see table 55 on page 129 ). the actual ocnx value will only be visible on the port pin if the data direction for the port pin is set as output (ddr_ocnx). the pwm waveform is gene rated by setting (or clearing) the ocnx register at the compare match between ocrnx and tcntn when the counter increments, and clearing (or setting) the ocnx register at compare match between ocrnx and tcntn when the counter decrements. the pwm frequency for the output when using phase correct pwm can be calculated by the following equation: the n variable represents the prescaler divider (1, 8, 64, 256, or 1024). for timer/counter3 also prescaler factors 16 and 32 are available. the extreme values for the ocrnx register represent special cases when generating a pwm waveform output in the phase correct pwm mode. if the ocrnx is set equal to bottom the output will be continuously low and if set equal to top the output will be continuously high for non-inverted pwm mode. for in verted pwm the output will have the opposite logic values. if ocrna is used to define the top value (wgmn3:0 = 11) and comna1:0 = 1, the ocna output will toggle with a 50% duty cycle. phase and frequency correct pwm mode the phase and frequency correct pulse width modulation, or phase and frequency correct pwm mode (wgmn3:0 = 8 or 9) provides a high reso lution phase and frequency correct pwm wave- form generation option. the phase and frequency correct pwm mode is, like the phase correct pwm mode, based on a dual-slope operation. the counter counts repeatedly from bottom (0x0000) to top and then from top to bottom. in non-inverting compare output mode, the output compare (ocnx) is cleared on the compare match between tcntn and ocrnx while up-counting, and set on the compare match while down-counting. in inverting compare output mode, the operation is inverted. the dual-slope operation gives a lower maximum operation fre- quency compared to the single-slope operation. howe ver, due to the symmetric feature of the dual-slope pwm modes, these modes are preferred for motor control applications. the main difference between the phase correct, and the phase and frequency correct pwm mode is the time the ocrnx register is updated by the ocrnx buffer register, (see figure 53 and figure 54 ). f ocnxpcpwm f clk_i/o 2 ntop ?? --------------------------- - = 124 2513k?avr?07/09 atmega162/v the pwm resolution for the phase and frequency correct pwm mode can be defined by either icrn or ocrna. the minimum resolution allowed is 2-bit (icrn or ocrna set to 0x0003), and the maximum resolution is 16-bit (icrn or ocrn a set to max). the pwm resolution in bits can be calculated using the following equation: in phase and frequency correct pwm mode the counter is incremented until the counter value matches either the value in icrn (wgmn3:0 = 8), or the value in ocrna (wgmn3:0 = 9). the counter has then reac hed the top and ch anges the count di rection. the tcntn value will be equal to top for one timer clock cycle. the timing diagram for the phase correct and frequency correct pwm mode is shown on figure 54 . the figure shows phase and frequency correct pwm mode when ocrna or icrn is used to define top. the tcntn value is in the timing diagram shown as a histogram for illustrating the dual- slope operation. the diagram incl udes non- inverted and inverted pwm outputs. the small horizontal line marks on the tcntn slopes repre- sent compare matches between o crnx and tcntn. the ocnx inte rrupt flag will be set when a compare match occurs. figure 54. phase and frequency correct pwm mode, timing diagram the timer/counter overflow flag (tovn) is set at the same timer clock cycle as the ocrnx registers are updated with the double buffer value (at bottom). when either ocrna or icrn is used for defining the top value, the ocna or icfn flag set when tcntn has reached top. the interrupt flags can then be used to generate an interrupt each time the counter reaches the top or bottom value. when changing the top value the program must ensure that the new top value is higher or equal to the value of all of the compare registers. if the top value is lower than any of the com- pare registers, a compare match will neve r occur between the tcntn and the ocrnx. as figure 54 shows the output generated is, in contrast to the phase correct mode, symmetrical in all periods. since the ocrnx registers are updated at bottom, the length of the rising and the falling slopes will always be equal. this gives sy mmetrical output pulses and is therefore fre- quency correct. r pfcpwm top 1 + () log 2 () log ---------------------------------- - = ocrnx/top update and tovn interrupt flag set (interrupt on bottom) ocna interrupt flag set or icfn interrupt flag set (interrupt on top) 1 2 3 4 tcntn period ocnx ocnx (comnx1:0 = 2) (comnx1:0 = 3) 125 2513k?avr?07/09 atmega162/v using the icrn register for defining top work s well when using fixed top values. by using icrn, the ocrna register is free to be used for generating a pwm output on ocna. however, if the base pwm frequency is actively changed by changing the top value, using the ocrna as top is clearly a better choice due to its double buffer feature. in phase and frequency correct pwm mode, the compare units allow generation of pwm wave- forms on the ocnx pins. settin g the comnx1:0 bits to two will produce a non-inverted pwm and an inverted pwm output can be generated by setting the comnx1:0 to three (see table 55 on page 129 ). the actual ocnx value will only be visible on the port pin if the data direction for the port pin is set as output (ddr_ocnx). the pwm waveform is generated by setting (or clearing) the ocnx register at the compare match between ocrnx and tcntn when the counter incre- ments, and clearing (or setting) the ocnx register at compare match between ocrnx and tcntn when the counter decrements. the pw m frequency for the output when using phase and frequency correct pwm can be calculated by the following equation: the n variable represents the prescaler divider (1, 8, 64, 256, or 1024). for timer/counter3 also prescaler factors 16 and 32 are available. the extreme values for the ocrnx register represents special cases when generating a pwm waveform output in the phase correct pwm mode. if the ocrnx is set equal to bottom the output will be continuously low and if set equal to top the output will be set to high for non- inverted pwm mode. for in verted pwm the output will have the opposite lo gic values. if ocrna is used to define the top va lue (wgmn3:0 = 9) and comna1:0 = 1, the ocna output will toggle with a 50% duty cycle. f ocnxpfcpwm f clk_i/o 2 ntop ?? --------------------------- - = 126 2513k?avr?07/09 atmega162/v timer/counter timing diagrams the timer/counter is a synchronous design and the timer clock (clk t n) is therefore shown as a clock enable signal in the following figures. the figures include information on when interrupt flags are set, and when the ocrnx register is updated with the ocrnx buffer value (only for modes utilizing doub le buffering). figure 55 shows a timing diagram for the setting of ocfnx. figure 55. timer/counter timing diagram, setting of ocfnx, no prescaling figure 56 shows the same timing data, but with the prescaler enabled. figure 56. timer/counter timing diagram, setting of ocfnx, with prescaler (f clk_i/o /8) figure 57 shows the count sequence close to top in various modes. when using phase and frequency correct pwm mode the ocrnx register is updated at bottom. the timing diagrams will be the same, but top should be replaced by bottom, top-1 by bottom+1 and so on. the same renaming applies for modes that set the tovn flag at bottom. clk tn (clk i/o /1) ocfnx clk i/o ocrnx tcntn ocrnx value ocrnx - 1 ocrnx ocrnx + 1 ocrnx + 2 ocfnx ocrnx tcntn ocrnx value ocrnx - 1 ocrnx ocrnx + 1 ocrnx + 2 clk i/o clk tn (clk i/o /8) 127 2513k?avr?07/09 atmega162/v figure 57. timer/counter timing diagram, no prescaling figure 58 shows the same timing data, but with the prescaler enabled. figure 58. timer/counter timing diagram, with prescaler (f clk_i/o /8) tovn (fpwm) and icfn (if used as top) ocrnx (update at top) tcntn (ctc and fpwm) tcntn (pc and pfc pwm) top - 1 top top - 1 top - 2 old ocrnx value new ocrnx value top - 1 top bottom bottom + 1 clk tn (clk i/o /1) clk i/o tovn (fpwm) and icfn (if used as top) ocrnx (update at top) tcntn (ctc and fpwm) tcntn (pc and pfc pwm) top - 1 top top - 1 top - 2 old ocrnx value new ocrnx value top - 1 top bottom bottom + 1 clk i/o clk tn (clk i/o /8) 128 2513k?avr?07/09 atmega162/v 16-bit timer/counter register description timer/counter1 control register a ? tccr1a timer/counter3 control register a ? tccr3a ? bit 7:6 ? comna1:0: compare output mode for channel a ? bit 5:4 ? comnb1:0: compare output mode for channel b the comna1:0 and comnb1:0 control the output compare pins (ocna and ocnb respec- tively) behavior. if one or both of the comna1:0 bits are written to one, the ocna output overrides the normal port functionality of the i/o pin it is connected to. if one or both of the comnb1:0 bit are written to one, the ocnb output overrides the normal port functionality of the i/o pin it is connected to. however, note that the data direction register (ddr) bit correspond- ing to the ocna or ocnb pin must be set in order to enable the output driver. when the ocna or ocnb is connected to the pin, the function of the comnx1:0 bits is depen- dent of the wgmn3:0 bits setting. table 53 shows the comnx1:0 bit functionality when the wgmn3:0 bits are set to a normal or a ctc mode (non-pwm). bit 76543210 com1a1 com1a0 com1b1 com1b0 foc1a foc1b wgm11 wgm10 tccr1a read/write r/w r/w r/w r/w w w r/w r/w initial value00000000 bit 76543210 com3a1 com3a0 com3b1 com3b0 foc3a foc3b wgm31 wgm30 tccr3a read/write r/w r/w r/w r/w w w r/w r/w initial value00000000 table 53. compare output mode, non-pwm comna1/ comnb1 comna0/ comnb0 description 0 0 normal port operation, ocna/ocnb disconnected. 0 1 toggle ocna/ocnb on compare match. 1 0 clear ocna/ocnb on compare match (set output to low level). 1 1 set ocna/ocnb on compare match (set output to high level). 129 2513k?avr?07/09 atmega162/v table 54 shows the comnx1:0 bit functionality when the wgmn3:0 bits are set to the fast pwm mode. note: 1. a special case occurs when ocrna/oc rnb equals top and comna1/comnb1 is set. in this case the compare match is ignored, but the set or clear is done at top. see ?fast pwm mode? on page 120. for more details. table 55 shows the comnx1:0 bit functionality when the wgmn3:0 bits are set to the phase cor- rect or the phase and frequency correct, pwm mode. note: 1. a special case occurs when ocrna/oc rnb equals top and comna1/comnb1 is set. see ?phase correct pwm mode? on page 122. for more details. ? bit 3 ? focna: force output compare for channel a ? bit 2 ? focnb: force output compare for channel b the focna/focnb bits are only active when the wgmn3:0 bits specifies a non-pwm mode. however, for ensuring compatibility with future devices, these bits must be set to zero when tccrna is written when operating in a pwm mode. when writing a logical one to the focna/focnb bit, an immediate compare match is forced on the waveform generation unit. the ocna/ocnb output is changed according to its comnx1:0 bits setting. note that the focna/focnb bits are implemented as strobes. therefore it is the value present in the comnx1:0 bits that determine the effect of the forced compare. a focna/focnb strobe will not generate any interrupt nor will it clear the timer in clear timer on compare match (ctc) mode using ocrna as top. the focna/focnb bits are always read as zero. table 54. compare output mode, fast pwm (1) comna1/ comnb1 comna0/ comnb0 description 0 0 normal port operation, ocna/ocnb disconnected. 0 1 wgmn3:0 = 15: toggle ocna on compare match, ocnb disconnected (normal port operation). for all other wgmn settings, normal port operation, ocna/ocnb disconnected. 1 0 clear ocna/ocnb on compare match, set ocna/ocnb at top. 1 1 set ocna/ocnb on compare match, clear ocna/ocnb at top. table 55. compare output mode, phase correct and phase and frequency correct pwm (1) comna1/ comnb1 comna0 comnb0 description 0 0 normal port operation, ocna/ocnb disconnected. 0 1 wgmn3:0 = 9 or 14: toggle oc na on compare match, ocnb disconnected (normal port operation). for all other wgmn settings, normal port operation, ocna/ocnb disconnected. 1 0 clear ocna/ocnb on compare match when up-counting. set ocna/ocnb on compare match when down-counting. 1 1 set ocna/ocnb on compare match when up-counting. clear ocna/ocnb on compare match when down-counting. 130 2513k?avr?07/09 atmega162/v ? bit 1:0 ? wgmn1:0: waveform generation mode combined with the wgmn3:2 bits found in the tccrnb register, these bits control the counting sequence of the counter, the source for maximum (top) counter value, and what type of wave- form generation to be used, see table 56 . modes of operation supported by the timer/counter unit are: normal mode (counter), clear timer on compare match (ctc) mode, and three types of pulse width modulation (pwm) modes. ( see ?modes of operation? on page 118. ) note: 1. the ctcn and pwmn1:0 bit definition names are obsolete . use the wgmn2:0 definitions. however, the functionality and location of these bits are compatible with previous versions of the timer. table 56. waveform generation mode bit description (1) mode wgmn3 wgmn2 (ctcn) wgmn1 (pwmn1) wgmn0 (pwmn0) timer/counter mode of operation top update of ocrn x at tovn flag set on 0 0 0 0 0 normal 0xffff immediate max 1 0 0 0 1 pwm, phase correct, 8-bit 0x00ff top bottom 2 0 0 1 0 pwm, phase correct, 9-bit 0x01ff top bottom 3 0 0 1 1 pwm, phase correct, 10-bit 0x03ff top bottom 4 0 1 0 0 ctc ocrna immediate max 5 0 1 0 1 fast pwm, 8-bit 0x00ff top top 6 0 1 1 0 fast pwm, 9-bit 0x01ff top top 7 0 1 1 1 fast pwm, 10-bit 0x03ff top top 8 1 0 0 0 pwm, phase and frequency correct icrn bottom bottom 9 1 0 0 1 pwm, phase and frequency correct ocrna bottom bottom 10 1 0 1 0 pwm, phase correct icrn top bottom 11 1 0 1 1 pwm, phase correct ocrna top bottom 12 1 1 0 0 ctc icrn immediate max 13 1 1 0 1 reserved ? ? ? 14 1 1 1 0 fast pwm icrn top top 15 1 1 1 1 fast pwm ocrna top top 131 2513k?avr?07/09 atmega162/v timer/counter1 control register b ? tccr1b timer/counter3 control register b ? tccr3b ? bit 7 ? icncn: input capture noise canceler setting this bit (to one) activates the input capture noise canceler. when the noise canceler is activated, the input from the input capture pin (icpn) is filtered. the filter function requires four successive equal valued samples of the icpn pin for changing its output. the input capture is therefore delayed by four oscillator cycles when the noise canceler is enabled. ? bit 6 ? icesn: input capture edge select this bit selects which edge on the input capture pin (icpn) that is used to trigger a capture event. when the icesn bit is written to zero, a falling (negative) edge is used as trigger, and when the icesn bit is written to one, a risi ng (positive) edge w ill trigger the capture. when a capture is triggered according to the icesn setting, the counter value is copied into the input capture register (icrn). the event will also set the input capture flag (icfn), and this can be used to cause an input capture interrupt, if this interrupt is enabled. when the icrn is used as top value (see description of the wgmn3:0 bits located in the tccrna and the tccrnb register), the icpn is disconnected and consequently the input cap- ture function is disabled. ? bit 5 ? reserved bit this bit is reserved for future use. for ensuring compatibility with future de vices, this bit must be written to zero when tccrnb is written. ? bit 4:3 ? wgmn3:2: waveform generation mode see tccrna register description. bit 76543210 icnc1 ices1 ? wgm13 wgm12 cs12 cs11 cs10 tccr1b read/write r/w r/w r r/w r/w r/w r/w r/w initial value 0 0 0 0 0 0 0 0 bit 76543210 icnc3 ices3 ? wgm33 wgm32 cs32 cs31 cs30 tccr3b read/write r/w r/w r r/w r/w r/w r/w r/w initial value 0 0 0 0 0 0 0 0 132 2513k?avr?07/09 atmega162/v ? bit 2:0 ? csn2:0: clock select the three clock select bits select the clock source to be used by the timer/counter, see figure 55 and figure 56 . if external pin modes are used for the timer/counter1, transitions on the t1 pin will clock the counter even if the pin is configured as an output. this feature allows software control of the counting.. table 57. clock select bit desc ription timer/counter1 cs12 cs11 cs10 description 0 0 0 no clock source. (timer/counter stopped). 001clk i/o /1 (no prescaling) 010clk i/o /8 (from prescaler) 011clk i/o /64 (from prescaler) 100clk i/o /256 (from prescaler) 101clk i/o /1024 (from prescaler) 1 1 0 external clock source on t1 pin. clock on falling edge. 1 1 1 external clock source on t1 pin. clock on rising edge. table 58. clock select bit desc ription timer/counter3 cs32 cs31 cs30 description 0 0 0 no clock source. (timer/counter stopped). 001clk i/o / 1 (no prescaling) 010clk i/o / 8 (from prescaler). 011clk i/o / 64 (from prescaler). 100clk i/o / 256 (from prescaler). 101clk i/o / 1024 (from prescaler). 110clk i/o / 16 (from prescaler). 111clk i/o / 32 (from prescaler). 133 2513k?avr?07/09 atmega162/v timer/counter1 ? tcnt1h and tcnt1l timer/counter3 ? tcnt3h and tcnt3l the two timer/counter i/o locations (tcntnh and tcntnl, combined tcntn) give direct access, both for read and for write operations, to the timer/counter unit 16-bit counter. to ensure that both the high and low bytes are read and written simultaneously when the cpu accesses these registers, the access is perfo rmed using an 8-bit temporary high byte register (temp). this temporary register is shared by all the other 16-bit registers. see ?accessing 16-bit registers? on page 109. modifying the counter (tcntn) while the counter is running introduces a risk of missing a com- pare match between tcntn and one of the ocrnx registers. writing to the tcntn register blocks (removes) the compare match on th e following timer clock for all compare units. output compare register 1 a ? ocr1ah and ocr1al output compare register 1 b ? ocr1bh and ocr1bl output compare register 3 a ? ocr3ah and ocr3al output compare register 3 b ? ocr3bh and ocr3bl bit 76543210 tcnt1[15:8] tcnt1h tcnt1[7:0] tcnt1l read/write r/w r/w r/w r/w r/w r/w r/w r/w initial value00000000 bit 76543210 tcnt3[15:8] tcnt3h tcnt3[7:0] tcnt3l read/write r/w r/w r/w r/w r/w r/w r/w r/w initial value00000000 bit 76543210 ocr1a[15:8] ocr1ah ocr1a[7:0] ocr1al read/write r/w r/w r/w r/w r/w r/w r/w r/w initial value00000000 bit 76543210 ocr1b[15:8] ocr1bh ocr1b[7:0] ocr1bl read/write r/w r/w r/w r/w r/w r/w r/w r/w initial value00000000 bit 76543210 ocr3a[15:8] ocr3ah ocr3a[7:0] ocr3al read/write r/w r/w r/w r/w r/w r/w r/w r/w initial value00000000 bit 76543210 ocr3b[15:8] ocr3bh ocr3b[7:0] ocr3bl read/write r/w r/w r/w r/w r/w r/w r/w r/w initial value00000000 134 2513k?avr?07/09 atmega162/v the output compare registers contain a 16-bit value that is continuously compared with the counter value (tcntn). a match can be used to generate an output compare interrupt, or to generate a waveform output on the ocnx pin. the output compare registers are 16-bit in size. to ensure that both the high and low bytes are written simultaneously when the cp u writes to these registers, the access is performed using an 8-bit temporary high byte register (temp). this temporary register is shared by all the other 16- bit registers. see ?accessing 16-bit registers? on page 109. input capture register 1 ? icr1h and icr1l input capture register 3 ? icr3h and icr3l the input capture is updated with the counter (tcntn) value each time an event occurs on the icpn pin (or optionally on the analog comparator output for timer/counter1). the input capture can be used for defining the counter top value. the input capture register is 16-bit in size. to ensure that both the high and low bytes are read simultaneously when the cpu accesses these regi sters, the access is performed using an 8-bit temporary high byte register (temp). this temporary register is shared by all the other 16-bit registers. see ?accessing 16-bit registers? on page 109. timer/counter interrupt mask register ? timsk (1) note: 1. this register contains interrupt control bits for several timer/counters, but only timer1 bits are described in this section. the remaining bits are described in their respective timer sections. ? bit 7 ? toie1: timer/counter1, overflow interrupt enable when this bit is written to one, and the i-flag in the status register is set (interrupts globally enabled), the timer/counter1 overflow interrupt is enabled. the corresponding interrupt vector ( see ?interrupts? on page 57. ) is executed when the tov1 flag, located in tifr, is set. ? bit 6 ? ocie1a: timer/counter1, output compare a match interrupt enable when this bit is written to one, and the i-flag in the status register is set (interrupts globally enabled), the timer/counter1 output compare a match interrupt is enabled. the corresponding interrupt vector ( see ?interrupts? on page 57. ) is executed when the ocf1a flag, located in tifr, is set. ? bit 5 ? ocie1b: timer/counter1, output compare b match interrupt enable when this bit is written to one, and the i-flag in the status register is set (interrupts globally enabled), the timer/counter1 output compare b match interrupt is enabled. the corresponding bit 76543210 icr1[15:8] icr1h icr1[7:0] icr1l read/write r/w r/w r/w r/w r/w r/w r/w r/w initial value00000000 bit 76543210 icr3[15:8] icr3h icr3[7:0] icr3l read/write r/w r/w r/w r/w r/w r/w r/w r/w initial value00000000 bit 76543210 toie1 ocie1a ocie1b ocie2 ticie1 toie2 toie0 ocie0 timsk read/write r/w r/w r/w r/w r/w r/w r/w r/w initial value 0 0 0 0 0 0 0 0 135 2513k?avr?07/09 atmega162/v interrupt vector ( see ?interrupts? on page 57. ) is executed when the ocf1b flag, located in tifr, is set. ? bit 3 ? ticie1: timer/counter1, input capture interrupt enable when this bit is written to one, and the i-flag in the status register is set (interrupts globally enabled), the timer/counter1 input capture interrupt is enabled. the corresponding interrupt vector ( see ?interrupts? on page 57. ) is executed when the icf1 flag, located in tifr, is set. extended timer/counter interrupt mask register ? etimsk (1) note: 1. this register contains interrupt control bits for several timer/counters, but only timer3 bits are described in this section. the remaining bits are described in their respective timer sections. ? bit 5 ? ticie3: timer/counter3, input capture interrupt enable when this bit is written to one, and the i-flag in the status register is set (interrupts globally enabled), the timer/counter3 input capture interrupt is enabled. the corresponding interrupt vector ( see ?interrupts? on page 57. ) is executed when the icf3 flag, located in tifr, is set. ? bit 4 ? ocie3a: timer/counter3, output compare a match interrupt enable when this bit is written to one, and the i-flag in the status register is set (interrupts globally enabled), the timer/counter3 output compare a match interrupt is enabled. the corresponding interrupt vector ( see ?interrupts? on page 57. ) is executed when the ocf3a flag, located in tifr, is set. ? bit 3 ? ocie3b: timer/counter3, output compare b match interrupt enable when this bit is written to one, and the i-flag in the status register is set (interrupts globally enabled), the timer/counter3 output compare b match interrupt is enabled. the corresponding interrupt vector ( see ?interrupts? on page 57. ) is executed when the ocf3b flag, located in tifr, is set. ? bit 2 ? toie3: timer/counter3, overflow interrupt enable when this bit is written to one, and the i-flag in the status register is set (interrupts globally enabled), the timer/counter3 overflow interrupt is enabled. the corresponding interrupt vector ( see ?interrupts? on page 57. ) is executed when the tov3 flag, located in tifr, is set. timer/counter interrupt flag register ? tifr (1) note: 1. this register contains flag bits for severa l timer/counters, but only timer1 bits are described in this section. the remaining bits are de scribed in their respective timer sections. ? bit 7 ? tov1: timer/counter1, overflow flag the setting of this flag is dependent of the wgmn3:0 bits setting. in normal and ctc modes, the tov1 flag is set when the timer overflows. refer to table 56 on page 130 for the tov1 flag behavior when using another wgmn3:0 bit setting. bit 7 6 5 4 3 2 1 0 ticie3 ocie3a ocie3b toie3 ? ?etimsk read/write r r r/w r/w r/w r/w r r initial value 0 0 0 0 0 0 0 0 bit 76543210 tov1 ocf1a oc1fb ocf2 icf1 tov2 tov0 ocf0 tifr read/write r/w r/w r/w r/w r/w r/w r/w r/w initial value00000000 136 2513k?avr?07/09 atmega162/v tov1 is automatically cleared when the timer/c ounter1 overflow interrupt vector is executed. alternatively, tov1 can be cleared by writing a logic one to its bit location. ? bit 6 ? ocf1a: timer/counter1, output compare a match flag this flag is set in the timer clock cycle afte r the counter (tcnt1) value matches the output compare register a (ocr1a). note that a forced output compare (foc 1a) strobe will not set the ocf1a flag. ocf1a is automatically cleared when the output compare match a interrupt vector is exe- cuted. alternatively, ocf1a can be cleared by writing a logic one to its bit location. ? bit 5 ? ocf1b: timer/counter1, output compare b match flag this flag is set in the timer clock cycle afte r the counter (tcnt1) value matches the output compare register b (ocr1b). note that a forced output compare (foc 1b) strobe will not set the ocf1b flag. ocf1b is automatically cleared when the output compare match b interrupt vector is exe- cuted. alternatively, ocf1b can be cleared by writing a logic one to its bit location. ? bit 3 ? icf1: timer/count er1, input capture flag this flag is set when a capture event occurs on the icp1 pin. when the input capture register (icr1) is set by the wgmn3:0 to be used as the top value, the icf1 flag is set when the coun- ter reaches the top value. icf1 is automatically cleared when the input capt ure interrupt vector is executed. alternatively, icf1 can be cleared by writing a logic one to its bit location. 137 2513k?avr?07/09 atmega162/v extended timer/counter interrupt flag register ? etifr (1) note: 1. this register contains flag bits for severa l timer/counters, but only timer3 bits are described in this section. the remaining bits are de scribed in their respective timer sections. ? bit 5 ? icf3: timer/count er3, input capture flag this flag is set when a capture event occurs on the icp3 pin. when the input capture register (icr3) is set by the wgmn3:0 to be used as the top value, the icf3 flag is set when the coun- ter reaches the top value. icf3 is automatically cleared when the input capt ure interrupt vector is executed. alternatively, icf3 can be cleared by writing a logic one to its bit location. ? bit 4 ? ocf3a: timer/counter3, output compare a match flag this flag is set in the timer clock cycle afte r the counter (tcnt3) value matches the output compare register a (ocr3a). note that a forced output compare (foc 3a) strobe will not set the ocf3a flag. ocf3a is automatically cleared when the output compare match a interrupt vector is exe- cuted. alternatively, ocf3a can be cleared by writing a logic one to its bit location. ? bit 3 ? ocf3b: timer/counter3, output compare b match flag this flag is set in the timer clock cycle afte r the counter (tcnt3) value matches the output compare register b (ocr3b). note that a forced output compare (foc 3b) strobe will not set the ocf3b flag. ocf3b is automatically cleared when the output compare match b interrupt vector is exe- cuted. alternatively, ocf3b can be cleared by writing a logic one to its bit location. ? bit 2 ? tov3: timer/counter3, overflow flag the setting of this flag is dependent of the wgmn3:0 bits setting. in normal and ctc modes, the tov3 flag is set when the timer overflows. refer to table 56 on page 130 for the tov3 flag behavior when using another wgmn3:0 bit setting. tov3 is automatically cleared when the timer/c ounter3 overflow interrupt vector is executed. alternatively, tov3 can be cleared by writing a logic one to its bit location. bit 76543210 icf3 ocf3a oc3fb tov3 ? ?etifr read/write r r r/w r/w r/w r/w r r initial value00000000 138 2513k?avr?07/09 atmega162/v 8-bit timer/counter2 with pwm and asynchronous operation timer/counter2 is a general purpose, single channel, 8-bit timer/counter module. the main features are: ? single channel counter ? clear timer on compar e match (auto reload) ? glitch-free, phase correct pu lse width modulator (pwm) ? frequency generator ? 10-bit clock prescaler ? overflow and compare match interrupt sources (tov2 and ocf2) ? allows clocking from external 32 khz wa tch crystal independent of the i/o clock overview a simplified block diagram of the 8-bit timer/counter is shown in figure 59 . for the actual place- ment of i/o pins, refer to ?pinout atmega162? on page 2 . cpu accessible i/o registers, including i/o bits and i/o pins, are shown in bold. the device-specific i/o register and bit loca- tions are listed in the ?8-bit timer/counter register description? on page 149 . figure 59. 8-bit timer/counter block diagram registers the timer/counter (tcnt2) and output compare register (ocr2) are 8-bit registers. interrupt request (shorten as int.req.) signals are all visible in the timer interrupt flag register (tifr). all interrupts are individually masked with the timer interrupt mask register (timsk). tifr and timsk are not shown in the figure since these registers are shared by other timer units. the timer/counter can be clocked internally, via the prescaler, or asynchronously clocked from the tosc1/2 pins, as detailed later in this section. the asynchronous operation is controlled by timer/counter databus = tcntn waveform generation ocn = 0 control logic = 0xff top bottom count clear direction tovn (int.req.) ocn (int.req.) synchronization unit ocrn tccrn assrn status flags clk i/o clk asy synchronized status flags asynchronous mode select (asn) tosc1 t/c oscillator tosc2 prescaler clk tn clk i/o 139 2513k?avr?07/09 atmega162/v the asynchronous status regist er (assr). the clock select lo gic block controls which clock source the timer/counter uses to increment (or de crement) its value. the timer/counter is inac- tive when no clock source is selected. the output from the clock select logic is referred to as the timer clock (clk t 2). the double buffered output compare register (ocr2) is compared with the timer/counter value at all times. the result of the compare can be used by the waveform generator to generate a pwm or variable frequency output on the output compare pin (oc2). see ?output compare unit? on page 140. for details. the compare match event will also set the compare flag (ocf2) which can be used to generate an output compare interrupt request. definitions many register and bit references in this document are written in general form. a lower case ?n? replaces the timer/counter number, in this case 2. however, when using the register or bit defines in a program, the precise form must be used i.e., tcnt2 for accessing timer/counter2 counter value and so on. the definitions in table 59 are also used extensively throughout the section. timer/counter clock sources the timer/counter can be clocked by an internal synchronous or an external asynchronous clock source. the clock source clk t 2 is by default equal to the mcu clock, clk i/o . when the as2 bit in the assr register is written to logic one, the clock source is taken from the timer/counter oscillator connecte d to tosc1 and tosc2. for details on asynchronous operation, see ?asyn- chronous status register ? assr? on page 152 . for details on clock so urces and prescaler, see ?timer/counter prescaler? on page 156 . table 59. definitions bottom the counter reaches the bottom when it becomes zero (0x00). max the counter reaches its maximum when it becomes 0xff (decimal 255). top the counter reaches the top when it becomes equal to the highest value in the count sequence. the top value can be assigned to be the fixed value 0xff (max) or the value stored in the ocr2 register. the assignment is dependent on the mode of operation. 140 2513k?avr?07/09 atmega162/v counter unit the main part of the 8-bit timer/counter is the programmable bi-directional counter unit. figure 60 shows a block diagram of the counter and its surrounding environment. figure 60. counter unit block diagram signal description (internal signals): count increment or decrement tcnt2 by 1. direction selects between increment and decrement. clear clear tcnt2 (set a ll bits to zero). clk t 2 timer/counter clock. top signalizes that tcnt2 has reached maximum value. bottom signalizes that tcnt2 has reached minimum value (zero). depending on the mode of operation used, the counter is cleared, incremented, or decremented at each timer clock (clk t 2). clk t 2 can be generated from an external or internal clock source, selected by the clock select bits (cs22:0). w hen no clock source is selected (cs22:0 = 0) the timer is stopped. however, the tcnt2 value can be accessed by the cpu, regardless of whether clk t 2 is present or not. a cpu write override s (has priority over) all counter clear or count operations. the counting sequence is determined by the setting of the wgm21 and wgm20 bits located in the timer/counter control register (tccr2). there are close connections between how the counter behaves (counts) and how waveforms are generated on the output compare output oc2. for more details about advanced counting sequences and waveform generation, see ?modes of operation? on page 143 . the timer/counter overflow flag (tov2) is set according to the mode of operation selected by the wgm21:0 bits. tov2 can be used for generating a cpu interrupt. output compare unit the 8-bit comparator continuously compares tcnt2 with the output compare register (ocr2). whenever tcnt2 equals ocr2, the comparator signals a match. a match will set the output compare flag (ocf2) at the next timer clock cycle. if enabled (ocie2 = 1), the output compare flag generates an output compare interrupt. the ocf2 flag is automatically cleared when the interrupt is executed. alternatively, th e ocf2 flag can be cleared by software by writ- ing a logical one to its i/o bit location. the waveform generator uses the match signal to generate an output according to operating mode set by the wgm21:0 bits and compare output mode (com21:0) bits. the max and bottom signals are used by the waveform generator for han- dling the special cases of the extreme values in some modes of operation ( ?modes of operation? on page 143 ). figure 61 shows a block diagram of the output compare unit. data b u s tcntn control logic count tovn (int.req.) top bottom direction clear tosc1 t/c oscillator tosc2 prescaler clk i/o clk tn 141 2513k?avr?07/09 atmega162/v figure 61. output compare unit, block diagram the ocr2 register is double buffered when us ing any of the pulse width modulation (pwm) modes. for the normal and clear timer on compare (ctc) modes of operation, the double buff- ering is disabled. the double buffering synchron izes the update of the ocr2 compare register to either top or bottom of the counting sequenc e. the synchronization prevents the occurrence of odd-length, non-symmetrical pwm pulses, thereby making the output glitch-free. the ocr2 register access may seem complex, but this is not case. when the double buffering is enabled, the cpu has access to the ocr2 buff er register, and if double buffering is disabled the cpu will access the ocr2 directly. force output compare in non-pwm waveform generation modes, the match output of the comparator can be forced by writing a one to the force output compare (foc2) bit. forcing compare match will not set the ocf2 flag or reload/clear the timer, but the oc2 pin will be updated as if a real compare match had occurred (the com21:0 bits settings define whether the oc2 pin is set, cleared or toggled). compare match blocking by tcnt2 write all cpu write operations to the tcnt2 register will block any comp are match that occurs in the next timer clock cycle, even when the timer is st opped. this feature allows ocr2 to be initialized to the same value as tcnt2 without triggering an interrupt when the timer/counter clock is enabled. using the output compare unit since writing tcnt2 in any mode of operation will block all comp are matches for one timer clock cycle, there are risks involved when changi ng tcnt2 when using the output compare channel, independently of whether the timer/counter is running or not. if the value written to tcnt2 equals the ocr2 value, the co mpare match will be missed, re sulting in incorrect waveform generation. similarly, do not write the tcnt2 value equal to bottom when the counter is down-counting. ocfn (int.req.) = (8-bit comparator ) ocrn ocxy data b u s tcntn wgmn1:0 waveform generator top focn comn1:0 bottom 142 2513k?avr?07/09 atmega162/v the setup of the oc2 should be performed before setting the data direction register for the port pin to output. the easiest way of setting the oc2 value is to use the force output compare (foc2) strobe bit in normal mode. the oc2 r egister keeps its value even when changing between waveform generation modes. be aware that the com21:0 bits are not double buffered together with the compare value. changing the com21:0 bits will take effect immediately. compare match output unit the compare output mode (com21:0) bits have two functions. the waveform generator uses the com21:0 bits for defining the output compare (oc2) state at the next compare match. also, the com21:0 bits control the oc2 pin output source. figure 62 shows a simplified sche- matic of the logic affected by the com21:0 bit setting. the i/o registers, i/o bits, and i/o pins in the figure are shown in bold. only the parts of the general i/o port control registers (ddr and port) that are affected by the com21:0 bits are shown. when referring to the oc2 state, the reference is for the internal oc2 register, not the oc2 pin. figure 62. compare match output unit, schematic the general i/o port function is overridden by the output compare (oc2) from the waveform generator if either of the com21:0 bits are set. however, the oc2 pin direction (input or output) is still controlled by the data direction register (ddr) for the port pin. the data direction regis- ter bit for the oc2 pin (ddr_oc2) must be set as output before the oc2 value is visible on the pin. the port override function is independent of the waveform generation mode. the design of the output compare pin logic allows initialization of the oc2 state before the out- put is enabled. note that some com21:0 bit settings are reserved for certain modes of operation. see ?8-bit timer/counter register description? on page 149. port ddr dq dq ocn pin ocn dq waveform generator comn1 comn0 0 1 data b u s focn clk i/o 143 2513k?avr?07/09 atmega162/v compare output mode and waveform generation the waveform generator uses the com21:0 bits differently in normal, ctc, and pwm modes. for all modes, setting the com21:0 = 0 tells the waveform generator that no action on the oc2 register is to be performed on the next compare match. for compare output actions in the non- pwm modes refer to table 61 on page 150 . for fast pwm mode, refer to table 62 on page 150 , and for phase correct pwm refer to table 63 on page 150 . a change of the com21:0 bits stat e will have effect at the first co mpare match after the bits are written. for non-pwm modes, the action can be fo rced to have immediate effect by using the foc2 strobe bits. modes of operation the mode of operation, i.e., the behavior of the timer/counter and the output compare pins, is defined by the combination of the waveform generation mode (wgm21:0) and compare output mode (com21:0) bits. the compare output mode bits do not affect the counting sequence, while the waveform generation mode bits do. the com21:0 bits control whether the pwm out- put generated should be inverted or not (inverted or non-inverted pwm). for non-pwm modes the com21:0 bits control whether the output should be set, cleared, or toggled at a compare match ( see ?compare match output unit? on page 142. ). for detailed timing information refer to ?timer/counter timing diagrams? on page 147 . normal mode the simplest mode of operation is the normal mode (wgm21:0 = 0). in this mode the counting direction is always up (incrementing), and no counter clear is performed. the counter simply overruns when it passes its maximum 8-bit value (top = 0xff) and then restarts from the bot- tom (0x00). in normal o peration the timer/counter overflow flag (tov2) will be set in the same timer clock cycle as the tcnt2 becomes zero. the tov2 flag in this case behaves like a ninth bit, except that it is only set, not cleared. however, combined with the timer overflow interrupt that automatically clears the tov2 flag, the timer resolution can be increased by software. there are no special cases to consider in the normal mode, a new counter value can be written anytime. the output compare unit can be used to generate interrupts at some given time. using the out- put compare to generate waveforms in normal mode is not recommended, since this will occupy too much of the cpu time. 144 2513k?avr?07/09 atmega162/v clear timer on compare match (ctc) mode in clear timer on compare or ctc mode (wgm21:0 = 2), the ocr2 register is used to manip- ulate the counter resolution. in ctc mode the counter is cleared to zero when the counter value (tcnt2) matches the ocr2. the ocr2 defines the top value for the counter, hence also its resolution. this mode allows greater control of the compare match output frequency. it also sim- plifies the operation of counting external events. the timing diagram for the ctc mode is shown in figure 63 . the counter value (tcnt2) increases until a compare match occurs between tcnt2 and ocr2, and then counter (tcnt2) is cleared. figure 63. ctc mode, timing diagram an interrupt can be generated each time the counter value reaches the top value by using the ocf2 flag. if the interrupt is enabled, the interrupt handler routine can be used for updating the top value. however, changing the top to a va lue close to bottom when the counter is run- ning with none or a low prescaler value must be done with care since the ctc mode does not have the double buffering feature. if the new value written to ocr2 is lower than the current value of tcnt2, the counter will miss the compar e match. the counter will then have to count to its maximum value (0xff) and wrap around starting at 0x00 before the compare match can occur. for generating a waveform output in ctc mode, the oc2 output can be set to toggle its logical level on each compare match by setting the compare output mode bits to toggle mode (com21:0 = 1). the oc2 value will no t be visible on the port pin unl ess the data direction for the pin is set to output. the waveform g enerated will have a maximum frequency of f oc 2 = f clk_i/o /2 when ocr2 is set to zero (0x00). the waveform frequency is defined by the following equation: the n variable represents the prescale factor (1, 8, 32, 64, 128, 256, or 1024). as for the normal mode of operation, the tov2 flag is set in the same timer clock cycle that the counter counts from max to 0x00. tcntn ocn (toggle) ocn interrupt flag set 1 4 period 2 3 (comn1:0 = 1) f ocn f clk_i/o 2 n 1 ocrn + () ?? ---------------------------------------------- - = 145 2513k?avr?07/09 atmega162/v fast pwm mode the fast pulse width modulation or fast pwm mode (wgm21:0 = 1) provides a high frequency pwm waveform generation option. the fast pwm di ffers from the other pwm option by its sin- gle-slope operation. the counter counts from bottom to max then restarts from bottom. in non-inverting compare output mode, the output compare (oc2) is cleared on the compare match between tcnt2 and ocr2, and set at bottom. in inverting compare output mode, the output is set on compare match and cleared at bottom. due to the single-slope operation, the operating frequency of the fast pwm mode can be twice as high as the phase correct pwm mode that uses dual-slope operation. this high frequency makes the fast pwm mode well suited for power regulation, rectification, and dac app lications. high frequency a llows physically small sized external components (coils, capacitors), and therefore reduces total system cost. in fast pwm mode, the counter is incremented until the counter value matches the max value. the counter is then cleared at the following timer clock cycle. the timing diagram for the fast pwm mode is shown in figure 64 . the tcnt2 value is in the timing diagram shown as a histo- gram for illustrating the single-s lope operation. the diagram includes non- inverted and inverted pwm outputs. the small horizontal line ma rks on the tcnt2 slopes represent compare matches between ocr2 and tcnt2. figure 64. fast pwm mode, timing diagram the timer/counter overflow flag ( tov2 ) is set each time the counter reaches max. if the inter- rupt is enabled, the interrupt handler routine can be used for updating the compare value. in fast pwm mode, the compare unit allows generation of pwm waveforms on the oc2 pin. set- ting the com21:0 bits to two will produce a non- inverted pwm and an inve rted pwm output can be generated by setting the com21:0 to three (see table 62 on page 150 ). the actual oc2 value will only be visible on the port pin if the data direction for the port pin is set as output. the pwm waveform is generated by setting (or clearing) the oc2 register at the compare match between ocr2 and tcnt2, and clearing (or setting) the oc2 register at the timer clock cycle the counter is cleared (changes from max to bottom). the pwm frequency for the output can be calculated by the following equation: the n variable represents the prescale factor (1, 8, 32, 64, 128, 256, or 1024). tcntn ocrn update and tovn interrupt flag set 1 period 2 3 ocn ocn (comn1:0 = 2) (comn1:0 = 3) ocrn interrupt flag set 4 5 6 7 f ocnpwm f clk_i/o n 256 ? ------------------ = 146 2513k?avr?07/09 atmega162/v the extreme values for the ocr2 register represent special cases when generating a pwm waveform output in the fast pwm mode. if the ocr2 is set equal to bottom, the output will be a narrow spike for each max+1 ti mer clock cycle. setting the ocr2 equal to max will result in a constantly high or low output (depending on the polarity of the output set by the com21:0 bits.) a frequency (with 50% duty cycle) waveform output in fast pwm mode can be achieved by set- ting oc2 to toggle its logical level on each compare match (com21:0 = 1). the waveform generated will have a maximum frequency of f oc 2 = f clk_i/o /2 when ocr2 is set to zero. this fea- ture is similar to the oc2 toggle in ctc mode, except the double buffer feature of the output compare unit is enabled in the fast pwm mode. phase correct pwm mode the phase correct pwm mode (wgm21:0 = 3) pr ovides a high resolution phase correct pwm waveform generation option. the phase correct pwm mode is based on a dual-slope operation. the counter counts repeatedly from bottom to max and then from max to bottom. in non- inverting compare output mode, the output compare (oc2) is cleared on the compare match between tcnt2 and ocr2 while up-counting, and set on the compare match while down- counting. in inverting output compare mode, the operation is inverted. the dual-slope operation has lower maximum operation frequency than single slope operation. however, due to the sym- metric feature of the dual-slope pwm modes, these modes are preferred for motor control applications. the pwm resolution for the phase correct pwm m ode is fixed to eight bits. in phase correct pwm mode the counter is incremented until the counter value matches max. when the counter reaches max, it changes the count direction. the tcnt2 value will be equal to max for one timer clock cycle. the timing diagram fo r the phase correct pwm mode is shown on figure 65 . the tcnt2 value is in the timing diagram shown as a histogram for illustrating the dual-slope operation. the diagram includes non-inverted and inverted pwm outputs. the small horizontal line marks on the tcnt2 slopes represent compare matches between ocr2 and tcnt2. figure 65. phase correct pwm mode, timing diagram the timer/counter overflow flag ( tov2 ) is set each time the counter reaches bottom. the interrupt flag can be used to generate an interrupt each time the counter reaches the bottom value. in phase correct pwm mode, the compare unit allows generation of pwm waveforms on the oc2 pin. setting the com21:0 bits to two will produce a non-inverted pwm. an inverted pwm output can be generated by setting the com21:0 to three (see table 63 on page 150 ). the tovn interrupt flag set ocn interrupt flag set 1 2 3 tcntn period ocn ocn (comn1:0 = 2) (comn1:0 = 3) ocrn update 147 2513k?avr?07/09 atmega162/v actual oc2 value will only be visibl e on the port pin if the data direction for the port pin is set as output. the pwm waveform is generated by clearing (or setting) the oc2 register at the com- pare match between ocr2 and tcnt2 when the counter increments, and setting (or clearing) the oc2 register at compare match between ocr2 and tcnt2 when the counter decrements. the pwm frequency for the output when using phase correct pwm can be calculated by the fol- lowing equation: the n variable represents the prescale factor (1, 8, 32, 64, 128, 256, or 1024). the extreme values for the ocr2 register represent special cases when generating a pwm waveform output in the phase correct pwm mode. if the ocr2 is set equal to bottom, the out- put will be continuously low and if set equal to max the output will be continuously high for non- inverted pwm mode. for inverted pwm the output will have the opposite logic values. at the very start of period 2 in figure 65 ocn has a transition from high to low even though there is no compare match. the point of this transition is to guarantee symmetry around bottom. there are two cases that give a transition without a compare match. ? ocr2 changes its value from max, like in figure 65 . when the ocr2 value is max the ocn pin value is the same as the result of a down-counting compare match. to ensure symmetry around bottom the ocn value at max must correspond to the result of an up- counting compare match. ? the timer starts counting from a value higher than the one in ocr2, and for that reason misses the compare match and hence the ocn change that would have happened on the way up. timer/counter timing diagrams the following figures show the timer/counter in synchronous mode, and the timer clock (clk t 2) is therefore shown as a clock enable signal. in asynchronous mode, clk i/o should be replaced by the timer/counter oscillator clock. the figures include information on when interrupt flags are set. figure 66 contains timing data for basic timer/ counter operation. the figure shows the count sequence close to the max value in all modes other than phase correct pwm mode. figure 66. timer/counter timing diagram, no prescaling figure 67 shows the same timing data, but with the prescaler enabled. f ocnpcpwm f clk_i/o n 510 ? ------------------ = clk tn (clk i/o /1) tovn clk i/o tcntn max - 1 max bottom bottom + 1 148 2513k?avr?07/09 atmega162/v figure 67. timer/counter timing diagram, with prescaler (f clk_i/o /8) figure 68 shows the setting of ocf2 in all modes except ctc mode. figure 68. timer/counter timing diagram, setting of ocf2, with prescaler (f clk_i/o /8) figure 69 shows the setting of ocf2 and the clearing of tcnt2 in ctc mode. figure 69. timer/counter timing diagram, clear ti mer on compare match mode, with pres- caler (f clk_i/o /8) tovn tcntn max - 1 max bottom bottom + 1 clk i/o clk tn (clk i/o /8) ocfn ocrn tcntn ocrn value ocrn - 1 ocrn ocrn + 1 ocrn + 2 clk i/o clk tn (clk i/o /8) ocfn ocrn tcntn (ctc) top top - 1 top bottom bottom + 1 clk i/o clk tn (clk i/o /8) 149 2513k?avr?07/09 atmega162/v 8-bit timer/counter register description timer/counter control register ? tccr2 ? bit 7 ? foc2: force output compare the foc2 bit is only active when the wgm bits specify a non-pwm mode. however, for ensur- ing compatibility with future devices, this bit must be set to zero when tccr2 is written when operating in pwm mode. when writing a logical one to the foc2 bit, an immediate compare match is forced on the waveform generation unit. the oc2 output is changed according to its com21:0 bits setting. note that the foc2 bit is implemented as a strobe. therefore it is the value present in the com21:0 bits that determines the effect of the forced compare. a foc2 strobe will not generate any interrupt, nor will it clear the timer in ctc mode using ocr2 as top. the foc2 bit is always read as zero. ? bit 6, 3 ? wgm21:0: waveform generation mode these bits control the counting sequence of the counter, the source for the maximum (top) counter value, and what type of waveform generation to be used. modes of operation supported by the timer/counter unit are: normal mode, clear timer on compare match (ctc) mode, and two types of pulse width modulation (pwm) modes. see table 60 and ?modes of operation? on page 143 . note: 1. the ctc2 and pwm2 bit definition names are now obsolete. use the wgm21:0 definitions. however, the functionality and location of these bits are compatible with previous versions of the timer. bit 76543210 foc2 wgm20 com21 com20 wgm21 cs22 cs21 cs20 tccr2 read/write w r/w r/w r/w r/w r/w r/w r/w initial value 0 0 0 0 0 0 0 0 table 60. waveform generation mode bit description (1) mode wgm21 (ctc2) wgm20 (pwm2) timer/counter mode of operation top update of ocr2 at tov2 flag set on 0 0 0 normal 0xff immediate max 1 0 1 pwm, phase correct 0xff top bottom 2 1 0 ctc ocr2 immediate max 3 1 1 fast pwm 0xff top max 150 2513k?avr?07/09 atmega162/v ? bit 5:4 ? com21:0: compare match output mode these bits control the output compare pin (oc2) behavior. if one or both of the com21:0 bits are set, the oc2 output overrides the normal port functionality of the i/o pin it is connected to. however, note that the data direction register (ddr) bit corresponding to oc2 pin must be set in order to enable the output driver. when oc2 is connected to the pin, the function of the com21:0 bits depends on the wgm21:0 bit setting. table 61 shows the com21:0 bit functionality when the wgm21:0 bits are set to a normal or ctc mode (non-pwm). table 62 shows the com21:0 bit functionality when the wgm21:0 bits are set to fast pwm mode. note: 1. a special case occurs when ocr2 equals to p and com21 is set. in this case, the compare match is ignored, but the set or clear is done at top. see ?fast pwm mode? on page 145 for more details. table 63 shows the com21:0 bit functionality when the wgm21:0 bits are set to phase correct pwm mode. note: 1. a special case occurs when ocr2 equals to p and com21 is set. in this case, the compare match is ignored, but the set or clear is done at top. see ?phase correct pwm mode? on page 146 for more details. table 61. compare output mode, non-pwm mode com21 com20 description 0 0 normal port operation, oc2 disconnected. 0 1 toggle oc2 on compare match. 1 0 clear oc2 on compare match. 1 1 set oc2 on compare match. table 62. compare output mode, fast pwm mode (1) com21 com20 description 0 0 normal port operation, oc2 disconnected. 01reserved 1 0 clear oc2 on compare match, set oc2 at top. 1 1 set oc2 on compare match, clear oc2 at top. table 63. compare output mode, phase correct pwm mode (1) com21 com20 description 0 0 normal port operation, oc2 disconnected. 01reserved 1 0 clear oc2 on compare match when up-counting. set oc2 on compare match when down-counting. 1 1 set oc2 on compare match when up-counting. clear oc2 on compare match when down-counting. 151 2513k?avr?07/09 atmega162/v ? bit 2:0 ? cs22:0: clock select the three clock select bits select the clock source to be used by the timer/counter, see table 64 . timer/counter register ? tcnt2 the timer/counter register gives direct ac cess, both for read and write operations, to the timer/counter unit 8-bit counter. writing to the tcnt2 register blocks (removes) the compare match on the following timer clock. modifying the counter (tcnt2) while the counter is running, introduces a risk of missing a compare match between tcnt2 and the ocr2 register. output compare register ? ocr2 the output compare register contains an 8-bit value that is continuously compared with the counter value (tcnt2). a match can be used to generate an output compare interrupt, or to generate a waveform output on the oc2 pin. table 64. clock select bit description cs22 cs21 cs20 description 0 0 0 no clock source (timer/counter stopped). 001 clk t 2 s /(no prescaling) 010clk t 2 s /8 (from prescaler) 011clk t 2 s /32 (from prescaler) 100clk t 2 s /64 (from prescaler) 101clk t 2 s /128 (from prescaler) 110clk t 2 s /256 (from prescaler) 111clk t 2 s /1024 (from prescaler) bit 76543210 tcnt2[7:0] tcnt2 read/write r/w r/w r/w r/w r/w r/w r/w r/w initial value00000000 bit 76543210 ocr2[7:0] ocr2 read/write r/w r/w r/w r/w r/w r/w r/w r/w initial value00000000 152 2513k?avr?07/09 atmega162/v asynchronous operation of the timer/counter asynchronous status register ? assr ? bit 3 ? as2: asynchronous timer/counter2 when as2 is written to zero, timer/counter2 is clocked from the i/o clock, clk i/o . when as2 is written to one, timer/counter2 is clocked from a crystal oscilla tor connected to the timer oscil- lator 1 (tosc1) pin. when the value of as2 is changed, the contents of tcnt2, ocr2, and tccr2 might be corrupted. ? bit 2 ? tcn2ub: timer/counter2 update busy when timer/counter2 operates asynchronously and tcnt2 is written, this bit becomes set. when tcnt2 has been updated from the temporary storage register, this bit is cleared by hard- ware. a logical zero in this bit indicates that tcnt2 is ready to be updated with a new value. ? bit 1 ? ocr2ub: output co mpare register2 update busy when timer/counter2 operates asynchronously and ocr2 is written, this bit becomes set. when ocr2 has been updated from the temporary storage register, this bit is cleared by hard- ware. a logical zero in this bit indicates that ocr2 is ready to be updated with a new value. ? bit 0 ? tcr2ub: timer/counter control register2 update busy when timer/counter2 operates asynchronously and tccr2 is written, this bit becomes set. when tccr2 has been updated from the temporary storage register, this bit is cleared by hard- ware. a logical zero in this bit indicates that tccr2 is ready to be updated with a new value. if a write is performed to any of the three timer/counter2 registers while its update busy flag is set, the updated value might get corrupted and cause an unintentional interrupt to occur. the mechanisms for reading tcnt2, ocr2, and tccr2 are different. when reading tcnt2, the actual timer value is read. when reading oc r2 or tccr2, the value in the temporary stor- age register is read. bit 76543 2 1 0 ? ? ? ? as2 tcn2ub ocr2ub tcr2ub assr read/writerrrrr/wr r r initial value 0 0 0 0 0 0 0 0 153 2513k?avr?07/09 atmega162/v asynchronous operation of timer/counter2 when timer/counter2 operates asynchronously, some considerations must be taken. ? warning: when switching between asynchronous and synchronous clocking of timer/counter2, the timer registers tcnt2, ocr2, and tccr2 might be corrupted. a safe procedure for switching clock source is: 1. disable the timer/counter2 interrupts by clearing ocie2 and toie2. 2. select clock source by setting as2 as appropriate. 3. write new values to tcnt2, ocr2, and tccr2. 4. to switch to asynchronous operation: wait for tcn2ub, ocr2ub, and tcr2ub. 5. clear the timer/counter2 interrupt flags. 6. enable interrupts, if needed. ? the oscillator is optimized for use with a 32.768 khz watch crystal. applying an external clock to the tosc1 pin may result in incorrect timer/counter2 operation. the cpu main clock frequency must be more than four times the oscillator frequency. ? when writing to one of the r egisters tcnt2, ocr2, or tccr2, the value is transferred to a temporary register, and latched after two positive edges on tosc1. the user should not write a new value before the contents of the temporary register have been transferred to its destination. each of the three mentioned registers have their individual temporary register, which means that e.g., writing to tcnt2 does not disturb an ocr2 write in progress. to detect that a transfer to the destination regist er has taken place, the asynchronous status register ? assr ha s been implemented. ? when entering power-save or extended standby mode after having written to tcnt2, ocr2, or tccr2, the user must wait until the written register has been updated if timer/counter2 is used to wake up the device. other wise, the mcu will enter sleep mode before the changes are effective. this is particularly important if the output compare2 interrupt is used to wake up the device, since the output compare function is disabled during writing to ocr2 or tcnt2. if the write cycle is not finished, and the mcu enters sleep mode before the ocr2ub bit returns to zero, th e device will never receive a compare match interrupt, and the mcu will not wake up. ? if timer/counter2 is used to wake the device up from power-save or extended standby mode, precautions must be taken if the user wants to re-enter one of these modes: the interrupt logic needs one tosc1 cycle to be reset. if the time between wake-up and re- entering sleep mode is less than one tosc1 cycle, the interrupt will not occur, and the device will fail to wake up. if the user is in doubt whether the time be fore re-entering power- save or extended standby mode is sufficient, the following algorithm can be used to ensure that one tosc1 cycle has elapsed: 1. write a value to tccr2, tcnt2, or ocr2. 2. wait until the corresponding update busy flag in assr returns to zero. 3. enter power-save or extended standby mode. ? when the asynchronous operation is selected, the 32.768 khz oscillator for timer/counter2 is always running, except in power-down and standby modes. after a power-up reset or wake-up from power-down or standby mode, the user should be aware of the fact that this oscillator might take as long as one second to stabilize. the us er is advised to wait for at least one second before using timer/counter2 after power-up or wake-up from power-down or standby mode. the contents of all timer/counter2 registers must be considered lost after a wake-up from power-down or standby mode due to unstable clock signal upon start- up, no matter whether the oscillator is in use or a clock signal is applied to the tosc1 pin. ? description of wake up from power-save or extended standby mode when the timer is clocked asynchronously: when the interrupt condit ion is met, the wake up process is started on the following cycle of the timer clock, that is, the timer is always advanced by at least one before the processor can read the counter value. after wake-up, the mcu is halted for four 154 2513k?avr?07/09 atmega162/v cycles, it executes the interrupt routine, and resumes execution from the instruction following sleep. ? reading of the tcnt2 register shortly after wake-up from power-save may give an incorrect result. since tcnt2 is clocked on the asynchronous tosc clock, reading tcnt2 must be done through a register synchronized to the internal i/o clock domain. synchronization takes place for every rising tosc1 edge. when waking up from power- save mode, and the i/o clock (clk i/o ) again becomes active, tcnt2 will read as the previous value (before entering sleep) until the next rising tosc1 edge. the phase of the tosc clock after waking up from power-save mode is essentially unpredictable, as it depends on the wake-up time. the recommended procedure for reading tcnt2 is thus as follows: 1. write any value to either of the registers ocr2 or tccr2. 2. wait for the corresponding update busy flag to be cleared. 3. read tcnt2. ? during asynchronous operation, the synchronization of the interrupt flags for the asynchronous timer takes th ree processor cycles plus one timer cycle. the timer is therefore advanced by at least one before th e processor can read the timer value causing the setting of the interrupt flag. the output compare pin is changed on the timer clock and is not synchronized to the processor clock. timer/counter interrupt mask register ? timsk ? bit 4 ? ocie2: timer/counter2 output compare match interrupt enable when the ocie2 bit is written to one and the i-bit in the status register is set (one), the timer/counter2 compare match interrupt is enabled. the corresponding interrupt is executed if a compare match in timer/counter2 occurs, i.e., when the ocf2 bit is set in the timer/counter interrupt flag register ? tifr. ? bit 2 ? toie2: timer/counter2 overflow interrupt enable when the toie2 bit is written to one and the i-bit in the status register is set (one), the timer/counter2 overflow interrupt is enabled. the corresponding interrupt is executed if an overflow in timer/counter2 occurs, i.e., when the tov2 bit is set in the timer/counter interrupt flag register ? tifr. bit 76543210 toie1 ocie1a ocie1b ocie2 ticie1 toie2 toie0 ocie0 timsk read/write r/w r/w r/w r/w r/w r/w r/w r/w initial value 0 0 0 0 0 0 0 0 155 2513k?avr?07/09 atmega162/v timer/counter interrupt flag register ? tifr ? bit 4 ? ocf2: output compare flag 2 the ocf2 bit is set (one) when a compare match occurs between the timer/counter2 and the data in ocr2 ? output compare register2. ocf2 is cleared by hardware when executing the corresponding interrupt handling vector. alternativ ely, ocf2 is cleared by writing a logic one to the flag. when the i-bit in sreg, ocie2 (timer/counter2 compare match interrupt enable), and ocf2 are set (one), the timer/counter2 compare match interrupt is executed. ? bit 2 ? tov2: timer/counter2 overflow flag the tov2 bit is set (one) when an overflow occu rs in timer/counter2. tov2 is cleared by hard- ware when executing the corresponding interrupt handling vector. alternatively, tov2 is cleared by writing a logic one to the flag. when the sr eg i-bit, toie2 (timer/counter2 overflow inter- rupt enable), and tov2 are set (one), the timer/ counter2 overflow interrupt is executed. in pwm mode, this bit is set when timer/coun ter2 changes counting direction at 0x00. bit 76543210 tov1 ocf1a oc1fb ocf2 icf1 tov2 tov0 ocf0 tifr read/write r/w r/w r/w r/w r/w r/w r/w r/w initial value00000000 156 2513k?avr?07/09 atmega162/v timer/counter prescaler figure 70. prescaler for timer/counter2 the clock source for timer/counter2 is named clk t2s . clk t2s is by default connected to the main system i/o clock clk i o . by setting the as2 bit in assr, timer/counter2 is asynchronously clocked from the tosc1 pin. this enables us e of timer/counter2 as a real time counter (rtc). when as2 is set, pins tosc1 and tosc 2 are disconnected from port d. a crystal can then be connected between the tosc1 and tosc2 pins to serve as an independent clock source for timer/counter2. the oscillator is optimized for use with a 32.768 khz crystal. apply- ing an external clock source to tosc1 is not recommended. for timer/counter2, the possible prescaled selections are: clk t2s /8, clk t2s /32, clk t2s /64, clk t2s /128, clk t2s /256, and clk t2s /1024. additionally, clk t2s as well as 0 (stop) may be selected. setting the psr2 bit in sfior resets the prescale r. this allows the user to operate with a pre- dictable prescaler. special function io register ? sfior ? bit 1 ? psr2: prescaler reset timer/counter2 when this bit is one, the time r/counter2 prescaler will be rese t. this bit is normally cleared immediately by hardware. if this bit is written when timer/counter2 is operating in asynchronous mode, the bit will remain one until the presca ler has been reset. the bit will not be cleared by hardware if the tsm bit is set. refer to the description of the ?bit 7 ? tsm: timer/counter syn- chronization mode? on page 105 for a description of the timer/counter synchronization mode. 10-bit t/c prescaler timer/counter2 clock source clk i/o clk t2s tosc1 as2 cs20 cs21 cs22 clk t2s /8 clk t2s /64 clk t2s /128 clk t2s /1024 clk t2s /256 clk t2s /32 0 psr2 clear clk t2 bit 7 6 5 4 3 2 1 0 tsm xmbk xmm2 xmm1 xmm0 pud psr2 psr310 sfior read/write r/w r/w r/w r/w r/w r/w r/w r/w initial val- ue 000 00000 157 2513k?avr?07/09 atmega162/v serial peripheral interface ? spi the serial peripheral interface (spi) allows hi gh-speed synchronous data transfer between the atmega162 and peripheral devices or between several avr devices. the atmega162 spi includes the following features: ? full-duplex, three-wire synchronous data transfer ? master or slave operation ? lsb first or msb first data transfer ? seven programmable bit rates ? end of transmission interrupt flag ? write collision flag protection ? wake-up from idle mode ? double speed (ck/2) master spi mode figure 71. spi block diagram (1) note: 1. refer to figure 1 on page 2 , and table 32 on page 72 for spi pin placement. the interconnection between master and slave cpus with spi is shown in figure 72 . the sys- tem consists of two shift registers, and a master clock generator. the spi master initiates the communication cycle when pu lling low the slave select ss pin of the desired slave. master and slave prepare the data to be sent in their respective shift registers, and the master generates the required clock pulses on the sck line to interchange data. data is always shifted from mas- ter to slave on the master out ? slave in, mosi, line, and from slave to master on the master in ? slave out, miso, line. after ea ch data packet, the master will synchronize the slave by pulling high the slave select, ss , line. when configured as a master, the spi interface has no automatic control of the ss line. this must be handled by user software before communication can start. when this is done, writing a spi2x spi2x divider /2/4/8/16/32/64/128 158 2513k?avr?07/09 atmega162/v byte to the spi data register starts the spi clock generator, and the hardware shifts the eight bits into the slave. after shifting one byte, th e spi clock generator stops, setting the end of transmission flag (spif). if the spi interrupt enable bit (spie) in the spcr register is set, an interrupt is requested. the master may continue to shift the next byte by writing it into spdr, or signal the end of packet by pulling high the slave select, ss line. the last incoming byte will be kept in the buffer register for later use. when configured as a slave, the spi interface will remain sleeping with miso tri-stated as long as the ss pin is driven high. in this state, software may update the contents of the spi data register, spdr, but the data will not be shifted out by incoming clock pulses on the sck pin until the ss pin is driven low. as one byte has been completely shifted, the end of transmission flag, spif is set. if the spi interrupt enable bit, spie, in the spcr register is set, an interrupt is requested. the slave may continue to place new data to be sent into spdr before reading the incoming data. the last incomi ng byte will be kept in the buffer register for later use. figure 72. spi master-slave interconnection the system is single buffered in the transmit di rection and double buffered in the receive direc- tion. this means that bytes to be transmitted cannot be written to the spi data register before the entire shift cycle is complet ed. when receiving data, however, a received character must be read from the spi data register before the next character has been completely shifted in. oth- erwise, the first byte is lost. in spi slave mode, the control logic will sample the incoming signal of the sck pin. to ensure correct sampling of the clock signal, the minimum low and high periods should be: low periods: longer than 2 cpu clock cycles. high periods: longer than 2 cpu clock cycles. when the spi is enabled, the data direction of the mosi, miso, sck, and ss pins is overridden according to table 65 . for more details on automatic port overrides, refer to ?alternate port functions? on page 68 . note: 1. see ?alternate functions of port b? on page 72 for a detailed description of how to define the direction of the user defined spi pins. table 65. spi pin overrides (1) pin direction, master spi direction, slave spi mosi user defined input miso input user defined sck user defined input ss user defined input msb master lsb 8-bit shift register msb slave lsb 8-bit shift register miso mosi spi clock generator sck ss miso mosi sck ss v cc shift enable 159 2513k?avr?07/09 atmega162/v the following code examples show how to initialize the spi as a master and how to perform a simple transmission. ddr_spi in the examples mu st be replaced by the actual data direction register controlling the spi pins. dd_mosi, dd_m iso, and dd_sck must be replaced by the actual data direction bits for these pins. e.g., if mosi is placed on pin pb5, replace dd_mosi with ddb5 and ddr_spi with ddrb. 160 2513k?avr?07/09 atmega162/v note: 1. the example code assumes that the pa rt specific header file is included. assembly code example (1) spi_masterinit: ; set mosi and sck outpu?, all others input ldi r17,(1< 163 2513k?avr?07/09 atmega162/v ? bit 4 ? mstr: master/slave select this bit selects master spi mode when written to one, and slave spi mode when written logic zero. if ss is configured as an input and is driven low while mstr is set, mstr will be cleared, and spif in spsr will become set. the user will th en have to set mstr to re-enable spi mas- ter mode. ? bit 3 ? cpol: clock polarity when this bit is written to one, sck is high when idle. when cpol is written to zero, sck is low when idle. refer to figure 73 and figure 74 for an example. the cpol functionality is summa- rized below: ? bit 2 ? cpha: clock phase the settings of the clock phase bit (cpha) determine if data is sampled on the leading (first) or trailing (last) edge of sck. refer to figure 73 and figure 74 for an example. the cpha func- tionality is summarized below: ? bits 1, 0 ? spr1, spr0: spi clock rate select 1 and 0 these two bits control the sck rate of the dev ice configured as a master. spr1 and spr0 have no effect on the slave. the relationship between sck and the oscillator clock frequency f osc is shown in the following table: table 66. cpol functionality cpol leading edge trailing edge 0 rising falling 1 falling rising table 67. cpha functionality cpha leading edge trailing edge 0 sample setup 1 setup sample table 68. relationship between sck an d the oscillator frequency spi2x spr1 spr0 sck frequency 000 f osc / 4 001 f osc / 16 010 f osc / 64 011 f osc / 128 100 f osc / 2 101 f osc / 8 110 f osc / 32 111 f osc / 64 164 2513k?avr?07/09 atmega162/v spi status register ? spsr ? bit 7 ? spif: spi interrupt flag when a serial transfer is complete, the spif flag is set. an interrupt is generated if spie in spcr is set and global interrupts are enabled. if ss is an input and is dr iven low when the spi is in master mode, this will also set the spif flag. spif is cleared by hardwa re when executing the corresponding interrupt handling vector. alternatively, the spif bit is cleared by first reading the spi status register with spif set, then accessing the spi data register (spdr). ? bit 6 ? wcol: write collision flag the wcol bit is set if the spi data register (spdr) is written during a data transfer. the wcol bit (and the spif bit) are cleared by first reading the spi status register with wcol set, and then accessing the spi data register. ? bit 5..1 ? res: reserved bits these bits are reserved bits in the atmega162 and will always read as zero. ? bit 0 ? spi2x: double spi speed bit when this bit is written logi c one the spi speed (sck freque ncy) will be doubled when the spi is in master mode (see table 68 ). this means that the minimum sck period will be two cpu clock periods. when the spi is configured as slave, the spi is only guaranteed to work at f osc /4 or lower. the spi interface on the atmega162 is also used for program memory and eeprom down- loading or uploading. see page 245 for spi serial programming and verification. spi data register ? spdr the spi data register is a read/write register used for data transfer between the register file and the spi shift register. writing to the register initiates data transmission. reading the regis- ter causes the shift register receive buffer to be read. bit 76543210 spifwcol?????spi2xspsr read/writerrrrrrrr/w initial value00000000 bit 76543210 msb lsb spdr read/write r/w r/w r/w r/w r/w r/w r/w r/w initial value x x x x x x x x undefined 165 2513k?avr?07/09 atmega162/v data modes there are four combinations of sck phase and polarity with respect to serial data, which are determined by control bits cpha and cpol. the spi data transfer formats are shown in figure 73 and figure 74 . data bits are shifted out and latched in on opposite edges of the sck signal, ensuring sufficient time for dat a signals to stabilize. this is clearly seen by summarizing table 66 and table 67 , as done below: figure 73. spi transfer format with cpha = 0 figure 74. spi transfer format with cpha = 1 table 69. cpol and cpha functionality leading edge trailing edge spi mode cpol=0, cpha=0 sample (rising) setup (falling) 0 cpol=0, cpha=1 setup (rising) sample (falling) 1 cpol=1, cpha=0 sample (falling) setup (rising) 2 cpol=1, cpha=1 setup (falling) sample (rising) 3 bit 1 bit 6 lsb msb sck (cpol = 0) mode 0 sample i mosi/miso change 0 mosi pin change 0 miso pin sck (cpol = 1) mode 2 ss msb lsb bit 6 bit 1 bit 5 bit 2 bit 4 bit 3 bit 3 bit 4 bit 2 bit 5 msb first (dord = 0) lsb first (dord = 1) sck (cpol = 0) mode 1 sample i mosi/miso change 0 mosi pin change 0 miso pin sck (cpol = 1) mode 3 ss msb lsb bit 6 bit 1 bit 5 bit 2 bit 4 bit 3 bit 3 bit 4 bit 2 bit 5 bit 1 bit 6 lsb msb msb first (dord = 0) lsb first (dord = 1) 166 2513k?avr?07/09 atmega162/v usart the universal synchronous and asynchronous serial receiver and transmitter (usart) is a highly flexible serial communication device. the main features are: ? full duplex operation (i ndependent serial receive and transmit registers) ? asynchronous or synchronous operation ? master or slave clocked synchronous operation ? high resolution baud rate generator ? supports serial frames with 5, 6, 7, 8, or 9 data bits and 1 or 2 stop bits ? odd or even parity generation and parity check supported by hardware ? data overrun detection ? framing error detection ? noise filtering includes false start bit detection and digital low pass filter ? three separate interrupts on tx complete , tx data register empty and rx complete ? multi-processor communication mode ? double speed asynchronous communication mode dual usart the atmega162 has two usarts, usart0 and usart1. the functionality for both usarts is described below. usart0 and usart1 have different i/o registers as shown in ?register summary? on page 304 . note that in atme ga161 compatibility mode, the double buff ering of the usart receive register is disabled. for details, see ?avr usart vs. avr uart ? compatibility? on page 168 . note also that the shared ubrrhi register in atmega161 has been split into two separate reg- isters, ubrr0h and ubrr1h, in atmega162. a simplified block diagram of the usart transmitter is shown in figure 75 . cpu accessible i/o registers and i/o pins are shown in bold. 167 2513k?avr?07/09 atmega162/v figure 75. usart block diagram (1) note: 1. refer to figure 1 on page 2 , table 34 on page 74 , table 39 on page 80 , and table 40 on page 80 for usart pin placement. the dashed boxes in the block diagram separate the three main parts of the usart (listed from the top): clock generator, transmitter and receiver. control registers are shared by all units. the clock generation logic consis ts of synchronization logic fo r external clock input used by synchronous slave operation, and the baud rate generator. the xck (transfer clock) pin is only used by synchronous transfer mode. the transmitter consists of a single write buffer, a serial shift register, parity generator and control logic for handling different serial frame formats. the write buffer allows a continuous transfer of data without any delay between frames. the receiver is the most complex part of the usart module due to its clock and data recovery units. the recovery units are used for asynchronous data reception. in addition to the recovery units, the receiver includes a parity checker, control logic, a shift register and a two level receive buffer (udr). the receiver supports the same frame formats as the transmitter, and can detect frame error, data overrun and parity errors. parity generator ubrr[h:l] udr (transmit) ucsra ucsrb ucsrc baud rate generator transmit shift register receive shift register rxd txd pin control udr (receive) pin control xck data recovery clock recovery pin control tx control rx control parity checker databus osc sync logic clock generator transmitter receiver 168 2513k?avr?07/09 atmega162/v avr usart vs. avr uart ? compatibility the usart is fully compatible with the avr uart regarding: ? bit locations inside all usart registers ? baud rate generation ? transmitter operation ? transmit buffer functionality ? receiver operation however, the receive bu ffering has two improvements that will affect the comp atibility in some special cases: ? a second buffer register has been added. the two buffer registers operate as a circular fifo buffer. therefore the udr must only be read once for each incoming data! more important is the fact that the error flags (fe and dor) and the ninth data bit (rxb8) are buffered with the data in the receive buffer. therefore the status bits must always be read before the udr register is read. otherwise the error status will be lost since the buffer state is lost. ? the receiver shift register can now act as a th ird buffer level. this is done by allowing the received data to remain in th e serial shift register (see figure 75 ) if the buffer registers are full, until a new start bit is detected. the usart is therefore more resistant to data overrun (dor) error conditions. the following control bits have changed name, but have same functionality and register location: ? chr9 is changed to ucsz2. ? or is changed to dor. clock generation the clock generation logic generates the base clock for the transmitter and receiver. the usart supports four modes of clock operati on: normal asynchronous, double speed asyn- chronous, master synchronous and slave sy nchronous mode. the umsel bit in usart control and status register c (ucsrc) selects between asynchronous and synchronous oper- ation. double speed (asynchronous mode only) is controlled by the u2x found in the ucsra register. when using synchronous mode (umsel = 1), the data direction register for the xck pin (ddr_xck) controls whether the clock source is internal (master mode) or external (slave mode). the xck pin is only active when using synchronous mode. figure 76 shows a block diagram of the clock generation logic. figure 76. clock generation logic, block diagram signal description: prescaling down-counter / 2 ubrr / 4 / 2 fosc ubrr+1 sync register osc xck pin txclk u2x umsel ddr_xck 0 1 0 1 xcki xcko ddr_xck rxclk 0 1 1 0 edge detector ucpol 169 2513k?avr?07/09 atmega162/v txclk transmitter clock. (internal signal) rxclk receiver base clock. (internal signal) xcki input from xck pin (internal signal). used for synchronous slave operation. xcko clock output to xck pin (internal signal). used for synchronous master operation. fosc xtal pin frequency (system clock). internal clock generation ? the baud rate generator internal clock generation is used for the as ynchronous and the synchronous master modes of operation. the description in this section refers to figure 76 . the usart baud rate register (ubrr) and the down-counter connected to it function as a programmable prescaler or baud rate generator. the down-counter, running at system clock (fosc), is loaded with the ubrr value each time the counter has counted down to zero or when the ubrrl register is written. a clock is gener ated each time the counter reaches zero. this clock is the baud rate generator clock output (= fosc/(ubrr+1)). the transmitter divides the baud rate generator clock output by 2, 8 or 16 depending on mode. the baud rate generator out- put is used directly by the receiver?s clock a nd data recovery units. however, the recovery units use a state machine that uses 2, 8 or 16 states depending on mode set by the state of the umsel, u2x and ddr_xck bits. table 70 contains equations for calculating the baud ra te (in bits per second) and for calculating the ubrr value for each mode of operation using an internally generated clock source. note: 1. the baud rate is defined to be the transfer rate in bit per second (bps). baud baud rate (in bits per second, bps) f osc system oscillator clock frequency ubrr contents of the ubrrh and ub rrl registers, (0 - 4095) some examples of ubrr values for some system clock frequencies are found in table 78 (see page 191 ). table 70. equations for calculating baud rate register setting operating mode equation for calculating baud rate (1) equation for calculating ubrr value asynchronous normal mode (u2x = 0) asynchronous double speed mode (u2x = 1) synchronous master mode baud f osc 16 ubrr 1 + () -------------------------------------- - = ubrr f osc 16 baud ----------------------- - 1 ? = baud f osc 8 ubrr 1 + () ----------------------------------- = ubrr f osc 8 baud -------------------- 1 ? = baud f osc 2 ubrr 1 + () ----------------------------------- = ubrr f osc 2 baud -------------------- 1 ? = 170 2513k?avr?07/09 atmega162/v double speed operation (u2x) the transfer rate can be doubled by setting the u2x bit in ucsra. setting this bit only has effect for the asynchronous operation. set this bi t to zero when using synchronous operation. setting this bit will reduce the divisor of the baud rate divider from 16 to 8, effectively doubling the transfer rate for asynchronous communication. note however that the receiver will in this case only use half the number of samples (reduced from 16 to 8) for data sampling and clock recovery, and therefore a more accurate baud rate setting and system clock are required when this mode is used. for the transmitter, there are no downsides. external clock external clocking is used by the synchronous sl ave modes of operation. the description in this section refers to figure 76 for details. external clock input from the xck pin is sampled by a synchronization register to minimize the chance of meta-stability. the output from the synchronization register must then pass through an edge detector before it can be used by the transmitter and receiver. this process intro- duces a two cpu clock period delay and theref ore the maximum external xck clock frequency is limited by the following equation: note that f osc depends on the stability of the system clock source. it is therefore recommended to add some margin to avoid possible loss of data due to frequency variations. synchronous clock operation when synchronous mode is used (umsel = 1), the xck pin will be used as either clock input (slave) or clock output (master). the dependency between the clock edges and data sampling or data change is the same. the basic principle is that data input (on rxd) is sampled at the opposite xck clock edge of the edge the data output (txd) is changed. figure 77. synchronous mode xck timing. the ucpol bit ucrsc selects which xck clock edge is used for data sampling and which is used for data change. as figure 77 shows, when ucpol is zero the data will be changed at ris- ing xck edge and sampled at falling xck edge. if ucpol is set, the data will be changed at falling xck edge and sampl ed at rising xck edge. f xck f osc 4 ----------- < rxd / txd xck rxd / txd xck ucpol = 0 ucpol = 1 sample sample 171 2513k?avr?07/09 atmega162/v frame formats a serial frame is defined to be one character of da ta bits with synchronizat ion bits (start and stop bits), and optionally a parity bi t for error checking. the usart accepts all 30 combinations of the following as valid frame formats: ? 1 start bit ? 5, 6, 7, 8, or 9 data bits ? no, even or odd parity bit ? 1 or 2 stop bits a frame starts with the start bit followed by the least significant data bit. then the next data bits, up to a total of nine, are succeeding, ending with t he most significant bit. if enabled, the parity bit is inserted after the data bits, before the stop bits. when a complete frame is transmitted, it can be directly followed by a new frame, or the communication line can be set to an idle (high) state. figure 78 illustrates the possible combinations of the frame formats. bits inside brackets are optional. figure 78. frame formats st start bit, always low. (n) data bits (0 to 8). p parity bit. can be odd or even. sp stop bit, always high. idle no transfers on the communication line (rxd or txd). an idle line must be high. the frame format used by the usart is set by the ucsz2:0, upm1:0 and usbs bits in ucsrb and ucsrc. the receiver and transmitter use the same setting. note that changing the setting of any of these bits will corrup t all ongoing communicati on for both the rece iver and transmitter. the usart character size (ucsz2:0) bits select the number of data bits in the frame. the usart parity mode (upm1:0) bits enable and set the type of parity bit. the selection between one or two stop bits is done by the usart stop bit select (usbs) bit. the receiver ignores the second stop bit. an fe (frame error) will therefor e only be detected in the cases where the first stop bit is zero. parity bit calculation the parity bit is calculated by do ing an exclusive-or of all the data bits. if odd parity is used, the result of the exclusive or is inverted. the re lation between the parity bit and data bits is as follows:: p even parity bit using even parity p odd parity bit using odd parity d n data bit n of the character if used, the parity bit is located between the last data bit and first stop bit of a serial frame. 1 0 2 3 4 [5] [6] [7] [8] [p] st sp1 [sp2] (st / idle) (idle) frame p even d n 1 ? d 3 d 2 d 1 d 0 0 p odd d n 1 ? d 3 d 2 d 1 d 0 1 = = 172 2513k?avr?07/09 atmega162/v usart initialization the usart has to be initialized before any communication can take place. the initialization pro- cess normally consists of setting the baud rate, setting frame format and enabling the transmitter or the receiver depending on the usage. for interrupt driven usart operation, the global interrupt flag should be cleared (and interrupts globally disabled) when doing the initialization. before doing a re-initialization with changed baud rate or frame format, be sure that there are no ongoing transmissions during the period the re gisters are changed. the txc flag can be used to check that the transmitter has completed all transfers, and the rxc flag can be used to check that there are no unread data in the receive buffer. note that the txc flag must be cleared before each transmission (before udr is written) if it is used for this purpose. the following simple usart initialization code examples show one assembly and one c func- tion that are equal in functionality. the exampl es assume asynchronous operation using polling (no interrupts enabled) and a fixed frame format. the baud rate is given as a function parameter. for the assembly code, the baud rate parameter is assumed to be stored in the r17:r16 regis- ters. when the function writes to the ucsrc re gister, the ursel bit (msb) must be set due to the sharing of i/o location by ubrrh and ucsrc. note: 1. see ?about code examples? on page 8 . assembly code example (1) usart_init: ; set baud rate out ubrrh, r17 out ubrrl, r16 ; enable receiver a?d transmitter ldi r16, (1< 176 2513k?avr?07/09 atmega162/v receiving frames with 5 to 8 data bits the receiver starts data reception when it detects a valid start bit. each bit that follows the start bit will be sampled at the ba ud rate or xck clock, and shifted into the receive shift register until the first stop bit of a frame is received. a seco nd stop bit will be ignored by the receiver. when the first stop bit is received, i.e., a complete serial frame is present in the receive shift register, the contents of the shift register will be moved into the receive buffer. the receive buffer can then be read by reading the udr i/o location. the following code example shows a simple us art receive function based on polling of the receive complete (rxc) flag. when using frames with less than eight bits the most significant bits of the data read from t he udr will be masked to zero. t he usart has to be initialized before the function can be used. note: 1. the example code assumes that the pa rt specific header file is included. the function simply waits for data to be present in the receive buffer by checking the rxc flag, before reading the buffer and returning the value. assembly code example (1) usart_receive: ; wait for data to ?e received sbis ucsra, rxc rjmp usart_receive ; get and return re?eived data from buffer in r16, udr ret c code example (1) unsigned char usart_receive( void ) { /* wait for data to?be received */ while ( !(ucsra & (?< 178 2513k?avr?07/09 atmega162/v the receive function example reads all the i/o r egisters into the register file before any com- putation is done. this gives an optimal receive buffer utilization since the bu ffer location read will be free to accept new data as early as possible. receive compete flag and interrupt the usart receiver has one flag that indicates the receiver state. the receive complete (rxc) flag indicates if there are unread data present in the receive buf- fer. this flag is one when unread data exist in the receive buffer, and zero when the receive buffer is empty (i.e., does not contain any unread data). if the receiver is disabled (rxen = 0), the receive buffer will be flushed and consequently the rxc bit will become zero. when the receive complete interrupt enable (rxcie) in ucsrb is set, the usart receive complete interrupt will be executed as long as the rxc flag is se t (provided that global inter- rupts are enabled). when interrupt-driven data reception is used, the receive complete routine must read the received data from udr in order to clear the rxc flag, otherwise a new interrupt will occur once the interr upt routine terminates. receiver error flags the usart receiver has three error flags: frame error (fe), data overrun (dor) and parity error (upe). all can be accessed by reading ucsra. common for the error flags is that they are located in the receive buffer together with the frame for which they indicate the error status. due to the buffering of the error flags, the ucsra must be read before the receive buffer (udr), since reading the udr i/o location changes the buffer read location. another equality for the error flags is that they can not be altered by software doing a write to the flag location. how- ever, all flags must be set to zero when the ucsra is written for upward compatibility of future usart implementations. none of the error flags can generate interrupts. the frame error (fe) flag indicates the state of the first stop bit of the next readable frame stored in the receive buffer. the fe flag is ze ro when the stop bit was correctly read (as one), and the fe flag will be one when the stop bit was incorrect (zero). this flag can be used for detecting out-of-sync conditions, detecting break conditions and protocol handling. the fe flag is not affected by the setting of the usbs bit in ucsrc since the re ceiver ignores all, except for the first, stop bits. for co mpatibility with future device s, always set this bit to zero when writing to ucsra. the data overrun (dor) flag indicates data loss du e to a receiver buffer full condition. a data overrun occurs when the receive buffer is full (two characters), it is a new character waiting in the receive shift register, and a new start bit is detected. if the dor flag is set there was one or more serial frame lost between the frame last read from udr, and the next frame read from udr. for compatibility with future devices, always write this bit to zero when writing to ucsra. the dor flag is cleared when the frame received was successfully moved from the shift regis- ter to the receive buffer. the parity error (upe) flag indicates that the next frame in the receive buffer had a parity error when received. if parity check is not enabled the upe bit will alwa ys be read zero. for compati- bility with future devices, always set this bi t to zero when wr iting to ucsra. fo r more details see ?parity bit calculation? on page 171 and ?parity checker? on page 179 . 179 2513k?avr?07/09 atmega162/v parity checker the parity checker is active when the high usart parity mode (upm1) bit is set. type of parity check to be performed (odd or even) is selected by the upm0 bit. when enabled, the parity checker calculates the parity of the data bits in incoming frames and compares the result with the parity bit from the serial frame. the result of the check is stored in the receive buffer together with the received data and stop bits. the parity error (upe) flag can then be read by software to check if the frame had a parity error. the upe bit is set if the next character that c an be read from the receive buffer had a parity error when received and the parity checking was enabled at that point (upm1 = 1). this bit is valid until the receive buff er (udr) is read. disabling the receiver in contrast to the transmitter, disabling of the receiver will be immediate. data from ongoing receptions will therefore be lost. when disabled (i.e., the rxen is set to zero) the receiver will no longer override the normal function of the rxd po rt pin. the receiver bu ffer fifo will be flushed when the receiver is disabled. remain ing data in the buffer will be lost flushing the receive buffer the receiver buffer fifo will be fl ushed when the receiver is disa bled, i.e., the buffer will be emptied of its contents. unread data will be lost. if the buffer has to be flushed during normal operation, due to for instance an error condition, read the udr i/o location until the rxc flag is cleared. the following code example shows how to flush the receive buffer. note: 1. the example code assumes that the pa rt specific header file is included. asynchronous data reception the usart includes a clock recovery and a data recovery unit for handling asynchronous data reception. the clock recovery logic is used fo r synchronizing the internally generated baud rate clock to the incoming asynchronous serial frames at the rxd pin. the data recovery logic sam- ples and low pass filters each incoming bit, thereby improving the noise immunity of the receiver. the asynchronous reception operational range depends on the accuracy of the internal baud rate clock, the rate of the incoming frames, and the frame size in number of bits. asynchronous clock recovery the clock recovery logic sync hronizes internal clock to the incoming serial frames. figure 79 illustrates the sampling process of th e start bit of an incoming frame. the sample rate is 16 times the baud rate for normal mode, and 8 times the baud rate for double speed mode. the horizon- tal arrows illustrate the synchronization variation due to the sampling process. note the larger time variation when using the double speed mode (u2x = 1) of operation. samples denoted zero are samples done when the rxd line is idle (i.e., no communication activity). assembly code example (1) usart_flush: sbis ucsra, rxc ret in r16, udr rjmp usart_flush c code example (1) void usart_flush( void ) { unsigned char dummy? while ( ucsra & (1 180 2513k?avr?07/09 atmega162/v figure 79. start bit sampling when the clock recovery logic detects a high (idle) to low (start) transition on the rxd line, the start bit detection sequence is initiated. let sample 1 denote the first zero-sample as shown in the figure. the clock recovery logic then uses samples 8, 9 and 10 for normal mode, and sam- ples 4, 5 and 6 for double speed mode (indicated with sample numbers inside boxes on the figure), to decide if a valid start bit is received. if two or more of these three samples have logical high levels (the majority wins), the start bit is rejected as a noise spike and the receiver starts looking for the next high to low-transition. if however, a valid start bit is detected, the clock recov- ery logic is synchronized and the data recove ry can begin. the sy nchronization process is repeated for each start bit. asynchronous data recovery when the receiver clock is synchronized to the start bit, the data recovery can begin. the data recovery unit uses a state machine that has 16 states for each bit in normal mode and 8 states for each bit in double speed mode. figure 80 shows the sampling of the data bits and the parity bit. each of the samples is given a number that is equal to the state of the recovery unit. figure 80. sampling of data and parity bit the decision of the logic level of the received bit is taken by doing a majori ty voting of the logic value to the three samples in the center of the received bit. the center samples are emphasized on the figure by having the sample number inside boxes. the majority voting process is done as follows: if two or all three samples have high levels, the received bit is registered to be a logic 1. if two or all three samples have low levels, the received bit is registered to be a logic 0. this majority voting process acts as a low pass filter for the incoming signal on the rxd pin. the recovery process is then repeated until a complete frame is received. including the first stop bit. note that the receiver only uses the first stop bit of a frame. figure 81 shows the sampling of the stop bit and the earliest possible beginning of the start bit of the next frame. 1234567 8 9 10 11 12 13 14 15 16 12 start idle 0 0 bit 0 3 123 4 5 678 12 0 rxd sample (u2x = 0) sample (u2x = 1) 1234567 8 9 10 11 12 13 14 15 16 1 bit n 123 4 5 678 1 rxd sample (u2x = 0) sample (u2x = 1) 181 2513k?avr?07/09 atmega162/v figure 81. stop bit sampling and ne xt start bit sampling the same majority voting is done to the stop bit as done for the other bits in the frame. if the stop bit is registered to have a logic 0 valu e, the frame error (f e) flag will be set. a new high to low transition indicating the start bit of a new frame can come right after the last of the bits used for majority voting. for normal speed mode, the first low level sample can be at point marked (a) in figure 81 . for double speed mode the first low level must be delayed to (b). (c) marks a stop bit of full length. the early start bit detection influences the operational range of the receiver. asynchronous operational range the operational range of the receiver is dependent on the mismatch between the received bit rate and the internally generated baud rate. if the transmitter is sending frames at too fast or too slow bit rates, or the internally generated baud rate of the receiver does not have a similar (see table 71 ) base frequency, the receiver will not be able to synchronize the frames to the start bit. the following equations can be used to calculate the ratio of the incoming data rate and internal receiver baud rate. d sum of character size and parity size (d = 5 to 10 bit) s samples per bit. s = 16 for normal speed mode and s = 8 for double speed mode. s f first sample number used for majority voting. s f = 8 for normal speed and s f = 4 for double speed mode. s m middle sample number used for majority voting. s m = 9 for normal speed and s m = 5 for double speed mode. r slow is the ratio of the slowest incoming data ra te that can be accepted in relation to the receiver baud rate. r fast is the ratio of the fastest incoming data rate that can be accepted in relation to the receiver baud rate. table 71 and table 72 list the maximum receiver baud rate error that can be tolerated. note that normal speed mode has higher toleration of baud rate variations. 1234567 8 9 10 0/1 0/1 0/1 stop 1 123 4 5 6 0/1 rxd sample (u2x = 0) sample (u2x = 1) (a) (b) (c) r slow d 1 + () s s 1 ? ds ? s f ++ ------------------------------------------ - = r fast d 2 + () s d 1 + () ss m + ----------------------------------- = 182 2513k?avr?07/09 atmega162/v the recommendations of the maximum receiver baud rate error was made under the assump- tion that the receiver and transmitter equally divides the maximum total error. there are two possible sources for the receivers baud rate error. the receiver?s system clock (xtal) will always have some minor instabilit y over the supply voltage range and the tempera- ture range. when using a crystal to generate the system clock, this is rarely a problem, but for a resonator the system clock may differ more than 2% depending of the resonators tolerance. the second source for the error is more controllable. the baud rate generator can not always do an exact division of the system frequency to get the b aud rate wanted. in this case an ubrr value that gives an acceptable low error can be used if possible. multi-processor communication mode setting the multi-processor communication mode (mpcm) bit in ucsra enables a filtering function of incoming frames received by the usart receiver. frames that do not contain address information will be ignored and not put in to the receive buffer. this effectively reduces the number of incoming frames that has to be handled by the cpu, in a system with multiple mcus that communicate via the same serial bus. the transmitter is unaffected by the mpcm setting, but has to be used diffe rently when it is a part of a system utilizing the multi-processor communication mode. if the receiver is set up to receive frames that c ontain 5 to 8 data bits, then the first stop bit indi- cates if the frame contains data or address information. if the receiver is set up for frames with nine data bits, then the ninth bit (rxb8) is used for identifying address and data frames. when the frame type bit (the first stop or the ninth bit) is one, the frame contains an address. when the frame type bit is zero the frame is a data frame. the multi-processor communication mode enables several slave mcus to receive data from a master mcu. this is done by first decoding an address frame to find out which mcu has been table 71. recommended maximum receiver baud rate error for normal speed mode (u2x = 0) d # (data+parity bit) r slow (%) r fast (%) max. total error (%) recommended max. receiver error (%) 5 93.20 106.67 +6.67/-6.8% 3.0 6 94.12 105.79 +5.79/-5.88 2.5 7 94.81 105.11 +5.11/-5.19 2.0 8 95.36 104.58 +4.58/-4.54 2.0 9 95.81 104.14 +4.14/-4.19 1.5 10 96.17 103.78 +3.7 /-3.83 1.5 table 72. recommended maximum receiver baud rate error for double speed mode (u2x = 1) d # (data+parity bit) r slow (%) r fast (%) max. total error (%) recommended max. receiver error (%) 5 94.12 105.66 +5.66/-5.88 2.5 6 94.92 104.92 +4.92/-5.08 2.0 7 95.52 104.35 +4.35/-4.48 1.5 8 96.00 103.90 +3.90/-4.00 1.5 9 96.39 103.53 +3.53/-3.61 1.5 10 96.70 103.23 +3.23/-3.30 1.0 183 2513k?avr?07/09 atmega162/v addressed. if a particular slave mcu has been addressed, it will rece ive the following data frames as normal, while the other slave mcus will ignore the received frames until another address frame is received. using mpcm for an mcu to act as a master mcu, it can use a 9-bit character frame format (ucsz = 7). the ninth bit (txb8) must be set when an address frame (txb8 = 1) or cleared when a data frame (txb = 0) is being transmitted. the slave mcus must in this case be set to use a 9-bit character frame format. the following procedure should be used to exchange data in multi-processor communication mode: 1. all slave mcus are in multi-processor co mmunication mode (mpcm in ucsra is set). 2. the master mcu sends an address frame, and all slaves receive and read this frame. in the slave mcus, the rxc flag in ucsra will be set as normal. 3. each slave mcu reads the udr register and dete rmines if it has been selected. if so, it clears the mpcm bit in ucsra, otherwise it waits for the next address byte and keeps the mpcm setting. 4. the addressed mcu will receive all data frames until a new address frame is received. the other slave mcus, which still have the mpcm bit set, will ignore the data frames. 5. when the last data frame is received by the addressed mcu, the addressed mcu sets the mpcm bit and waits for a new address frame from master. the process then repeats from 2. using any of the 5- to 8-bit character frame formats is possible, but impractical since the receiver must change between using n and n+1 character frame formats. this makes full-duplex opera- tion difficult since the transmitter and receiver uses the same character size setting. if 5 to 8 bit character frames are used, the tr ansmitter must be set to use tw o stop bit (usbs = 1) since the first stop bit is used for indicating the frame type. do not use read-modify-write instructions (sbi and cbi) to set or clear the mpcm bit. the mpcm bit shares the same i/o location as the txc flag and this might accidentally be cleared when using sbi or cbi instructions. 184 2513k?avr?07/09 atmega162/v accessing ubrrh/ ucsrc registers the ubrrh register shares the same i/o location as the ucsrc register. therefore some special consideration must be taken when accessing this i/o location. write access when doing a write access of this i/o location, the high bit of the value written, the usart reg- ister select (ursel) bit, controls which one of the two registers that will be written. if ursel is zero during a write operation, the ubrrh valu e will be updated. if ursel is one, the ucsrc setting will be updated. the following code examples show how to access the two registers. note: 1. the example code assumes that the pa rt specific header file is included. as the code examples illustrate, write accesses of the two registers are relatively unaffected of the sharing of i/o location. assembly code examples (1) ... ; set ubrrh to 2 ldi r16,0x02 out ubrrh,r16 ... ; set the usbs and ?he ucsz1 bit to one, and ; t he remaining bit? to zero. ldi r16,(1< 186 2513k?avr?07/09 atmega162/v usart register description usart i/o data register ? udr the usart transmit data buffer register and usart receive data buffer registers share the same i/o address referred to as usart data register or udr. the transmit data buffer reg- ister (txb) will be the destination for data wri tten to the udr register location. reading the udr register location will return the contents of the receive data bu ffer register (rxb). for 5-, 6-, or 7-bit char acters the upper unu sed bits will be ignored by the transmitter and set to zero by the receiver. the transmit buffer can only be written when the udre flag in the ucsra register is set. data written to udr when the udre flag is not set, will be ignored by the u sart transmitter. when data is written to the tr ansmit buffer, and the transmitter is enabled, the transm itter will load the data into the transmit shift register when the shift register is empty. then the data will be seri- ally transmitted on the txd pin. the receive buffer consists of a two level fifo . the fifo will change its state whenever the receive buffer is accessed. due to this behavior of the receive buffer, do not use read modify write instructions (sbi and cbi) on this location. be careful when using bit test instructions (sbic and sbis), since these also will change the state of the fifo. usart control and status register a ? ucsra ? bit 7 ? rxc: usar t receive complete this flag bit is set when there are unread data in the receive buffer and cleared when the receive buffer is empty (i.e., does not contain any unread data). if the receiver is disabled, the receive buffer will be flushed and consequently the rx c bit will become zero. the rxc flag can be used to generate a receive complete inte rrupt (see description of the rxcie bit). ? bit 6 ? txc: usart transmit complete this flag bit is set when the entire frame in the transmit shift register has been shifted out and there are no new data currently present in the transmit buffer (udr). the txc flag bit is auto- matically cleared when a transmit complete interrupt is executed, or it can be cleared by writing a one to its bit location. the txc flag can generate a transmit complete interrupt (see descrip- tion of the txcie bit). ? bit 5 ? udre: usart data register empty the udre flag indicates if the transmit buffer (udr) is ready to receive new data. if udre is one, the buffer is empty, and th erefore ready to be written. the udre flag can generate a data register empty interrupt (see description of the udrie bit). udre is set after a reset to indicate that the transmitter is ready. bit 76543210 rxb[7:0] udr (read) txb[7:0] udr (write) read/write r/w r/w r/w r/w r/w r/w r/w r/w initial value00000000 bit 76543210 rxc txc udre fe dor upe u2x mpcm ucsra read/write r r/w r r r r r/w r/w initial value00100000 187 2513k?avr?07/09 atmega162/v ? bit 4 ? fe: frame error this bit is set if the next character in the receive buffer had a frame error when received. i.e., when the first stop bit of the next character in the receive buffer is zero. this bit is valid until the receive buffer (udr) is read. the fe bit is zero when the stop bit of received da ta is one. always set this bit to zero when writing to ucsra. ? bit 3 ? dor: data overrun this bit is set if a data overrun condition is detected. a data overrun occurs when the receive buffer is full (two characters), it is a new character waiting in the receive shift register, and a new start bit is detected. this bit is valid until the receive buffer (u dr) is read. always set this bit to zero when writing to ucsra. ? bit 2 ? upe: parity error this bit is set if the next character in the receive buffer had a parity error when received and the parity checking was enabled at that point (upm1 = 1). this bit is valid until the receive buffer (udr) is read. always set this bit to zero when writing to ucsra. ? bit 1 ? u2x: double the usart transmission speed this bit only has effect for the asynchronous operation. write this bit to zero when using syn- chronous operation. writing this bit to one will reduce the divisor of the baud rate divider from 16 to 8 effectively dou- bling the transfer rate for asynchronous communication. ? bit 0 ? mpcm: multi-processor communication mode this bit enables the multi-processor communication mode. when the mpcm bit is written to one, all the incoming frames received by the usart receiver that do not contain address infor- mation will be ignored. the trans mitter is unaffected by the mp cm setting. for more detailed information see ?multi-processor communication mode? on page 182 . usart control and status register b ? ucsrb ? bit 7 ? rxcie: rx complete interrupt enable writing this bit to one enables interrupt on the rxc flag. a us art receive complete interrupt will be generated only if the rxcie bi t is written to one, the global interrupt flag in sreg is writ- ten to one and the rxc bit in ucsra is set. ? bit 6 ? txcie: tx complete interrupt enable writing this bit to one enables interrupt on the txc flag. a usart transmit complete interrupt will be generated only if the txcie bit is written to one, the glo bal interrupt flag in sreg is writ- ten to one and the txc bit in ucsra is set. ? bit 5 ? udrie: usart data register empty interrupt enable writing this bit to one enables interrupt on the udre flag. a da ta register empty interrupt will be generated only if the udrie bit is written to one, the glob al interrupt flag in sreg is written to one and the udre bit in ucsra is set. bit 76543210 rxcie txcie udrie rxen txen ucsz2 rxb8 txb8 ucsrb read/write r/w r/w r/w r/w r/w r/w r r/w initial value00000000 188 2513k?avr?07/09 atmega162/v ? bit 4 ? rxen: receiver enable writing this bit to one enables the usart receiv er. the receiver will override normal port oper- ation for the rxd pin when enabled. disabling the receiver will flush the receive buffer invalidating the fe, dor and upe flags. ? bit 3 ? txen: transmitter enable writing this bit to one enables the usart tr ansmitter. the transmitter will override normal port operation for the txd pin when enabled. the disabling of the transmitter (writing txen to zero) will not become effective until ongo ing and pending transmissions ar e completed, i. e., when the transmit shift register and transmit buffer register do not contain data to be transmitted. when disabled, the transmitter will no longer override the txd port. ? bit 2 ? ucsz2: character size the ucsz2 bits combined with the ucsz1:0 bit in ucsrc sets the number of data bits (charac- ter size) in a frame the receiver and transmitter use. ? bit 1 ? rxb8: receive data bit 8 rxb8 is the ninth data bit of the received charac ter when operating with serial frames with nine data bits. must be read before reading the low bits from udr. ? bit 0 ? txb8: transmit data bit 8 txb8 is the 9th data bit in the character to be transmitted when operating with serial frames with 9 data bits. must be written before writing the low bits to udr. 189 2513k?avr?07/09 atmega162/v usart control and status register c ? ucsrc (1) note: 1. the ucsrc register shares the same i/o location as the ubrrh register. see the ?access- ing ubrrh/ ucsrc registers? on page 184 section which describes how to access this register. ? bit 7 ? ursel: register select this bit selects between accessing the ucsrc or the ubrrh register. it is read as one when reading ucsrc. the ursel must be one when writ ing the ucsrc. ? bit 6 ? umsel: usart mode select this bit selects between asynchronous and synchronous mode of operation. ? bit 5:4 ? upm1:0: parity mode these bits enable and set type of parity generation and check. if enabled, the transmitter will automatically generate and send the parity of th e transmitted data bits within each frame. the receiver will generate a parity va lue for the incoming data and comp are it to the upm0 setting. if a mismatch is detected, the upe flag in ucsra will be set. ? bit 3 ? usbs: stop bit select this bit selects the number of stop bits to be inserted by the transmitter. the receiver ignores this setting. bit 76543210 ursel umsel upm1 upm0 usbs ucsz1 ucsz0 ucpol ucsrc read/write r/w r/w r/w r/w r/w r/w r/w r/w initial value10000110 table 73. umsel bit settings umsel mode 0 asynchronous operation 1 synchronous operation table 74. upm bits settings upm1 upm0 parity mode 0 0 disabled 01reserved 1 0 enabled, even parity 1 1 enabled, odd parity table 75. usbs bit settings usbs stop bit(s) 01-bit 12-bit 190 2513k?avr?07/09 atmega162/v ? bit 2:1 ? ucsz1:0: character size the ucsz1:0 bits combined with the ucsz2 bit in ucsrb sets the number of data bits (char- acter size) in a frame the receiver and transmitter use. ? bit 0 ? ucpol: clock polarity this bit is used for synchronous mode only. write this bit to zero when asynchronous mode is used. the ucpol bit sets the relationship between data output change and data input sample, and the synchronous clock (xck). usart baud rate registers ? ubrrl and ubrrh (1) note: 1. the ubrrh register shares the same i/o location as the ucsrc register. see the ?access- ing ubrrh/ ucsrc registers? on page 184 section which describes how to access this register. ? bit 15 ? ursel: register select this bit selects between accessing the ubrrh or the ucsrc register. it is read as zero when reading ubrrh. the ursel must be zero when writing the ubrrh. ? bit 14:12 ? reserved bits these bits are reserved for future use. for compatibility with future devices, these bit must be written to zero when ubrrh is written. table 76. ucsz bits settings ucsz2 ucsz1 ucsz0 character size 0005-bit 0016-bit 0107-bit 0118-bit 100reserved 101reserved 110reserved 1119-bit table 77. ucpol bit settings ucpol transmitted data changed (output of txd pin) received data sampled (input on rxd pin) 0 rising xck edge falling xck edge 1 falling xck edge rising xck edge bit 151413121110 9 8 ursel ? ? ? ubrr[11:8] ubrrh ubrr[7:0] ubrrl 76543210 read/write r/w r r r r/w r/w r/w r/w r/w r/w r/w r/w r/w r/w r/w r/w initial value00000000 00000000 191 2513k?avr?07/09 atmega162/v ? bit 11:0 ? ubrr11:0: usart baud rate register this is a 12-bit register which contains the usart baud rate. the ubrrh contains the four most significant bits, and the ubrrl contains th e eight least significant bits of the usart baud rate. ongoing transmissions by the transmitter and receiver will be corrupted if the baud rate is changed. writing ubrrl will tr igger an immediate update of the baud rate prescaler. examples of baud rate setting for standard crystal and resonator frequencies, the most commonly used baud rates for asyn- chronous operation can be generated by using the ubrr settings in table 78 . ubrr values which yield an actual baud rate differing less than 0.5% from the target baud rate, are bold in the table. higher error ratings are acceptable, but t he receiver will have less noise resistance when the error ratings are high, especially for large serial frames (see ?asynchronous operational range? on page 181 ). the error values are calculated using the following equation: error[%] baudrate closest match baudrate -------------------------------------------------------- 1 ? ?? ?? 100% ? = table 78. examples of ubrr settings for co mmonly used oscillator frequencies baud rate (bps) f osc = 1.0000 mhz f osc = 1.8432 mhz f osc = 2.0000 mhz u2x = 0 u2x = 1 u2x = 0 u2x = 1 u2x = 0 u2x = 1 ubrr error ubrr error ubrr error ubrr error ubrr error ubrr error 2400 250.2%510.2%470.0%950.0%510.2%1030.2% 4800 120.2%250.2%230.0%470.0%250.2%510.2% 9600 6 -7.0% 12 0.2% 11 0.0% 23 0.0% 12 0.2% 25 0.2% 14.4k 3 8.5% 8 -3.5% 7 0.0% 15 0.0% 8 -3.5% 16 2.1% 19.2k 2 8.5% 6 -7.0% 5 0.0% 11 0.0% 6 -7.0% 12 0.2% 28.8k 1 8.5% 3 8.5% 3 0.0% 7 0.0% 3 8.5% 8 -3.5% 38.4k 1 -18.6% 2 8.5% 2 0.0% 5 0.0% 2 8.5% 6 -7.0% 57.6k 0 8.5% 1 8.5% 1 0.0% 3 0.0% 1 8.5% 3 8.5% 76.8k ? ? 1 -18.6% 1 -25.0% 2 0.0% 1 -18.6% 2 8.5% 115.2k ? ? 0 8.5% 0 0.0% 1 0.0% 0 8.5% 1 8.5% 230.4k??????00.0%???? 250k??????????00.0% max. (1) 62.5 kbps 125 kbps 115.2 kbps 2 30.4 kbps 125 kbps 250 kbps 1. ubrr = 0, error = 0.0% 192 2513k?avr?07/09 atmega162/v table 79. examples of ubrr settings for commonl y used oscillator frequencies (continued) baud rate (bps) f osc = 3.6864 mhz f osc = 4.0000 mhz f osc = 7.3728 mhz u2x = 0 u2x = 1 u2x = 0 u2x = 1 u2x = 0 u2x = 1 ubrr error ubrr error ubrr error ubrr error ubrr error ubrr error 2400 95 0.0% 191 0.0% 103 0.2% 207 0.2% 191 0.0% 383 0.0% 4800 47 0.0% 95 0.0% 51 0.2% 103 0.2% 95 0.0% 191 0.0% 9600 230.0%470.0%250.2%510.2%470.0%950.0% 14.4k 15 0.0% 31 0.0% 16 2.1% 34 -0.8% 31 0.0% 63 0.0% 19.2k 11 0.0% 23 0.0% 12 0.2% 25 0.2% 23 0.0% 47 0.0% 28.8k 7 0.0% 15 0.0% 8 -3.5% 16 2.1% 15 0.0% 31 0.0% 38.4k 5 0.0% 11 0.0% 6 -7.0% 12 0.2% 11 0.0% 23 0.0% 57.6k 3 0.0% 7 0.0% 3 8.5% 8 -3.5% 7 0.0% 15 0.0% 76.8k 2 0.0% 5 0.0% 2 8.5% 6 -7.0% 5 0.0% 11 0.0% 115.2k 1 0.0% 3 0.0% 1 8.5% 3 8.5% 3 0.0% 7 0.0% 230.4k 0 0.0% 1 0.0% 0 8.5% 1 8.5% 1 0.0% 3 0.0% 250k 0 -7.8% 1 -7.8% 0 0.0% 1 0.0% 1 -7.8% 3 -7.8% 0.5m ? ? 0 -7.8% ? ? 0 0.0% 0 -7.8% 1 -7.8% 1m ??????????0-7.8% max. (1) 230.4 kbps 460.8 kbps 250 kbps 0.5 mbps 460.8 kbps 921.6 kbps 1. ubrr = 0, error = 0.0% 193 2513k?avr?07/09 atmega162/v table 80. examples of ubrr settings for commonl y used oscillator frequencies (continued) baud rate (bps) f osc = 8.0000 mhz f osc = 11.0592 mhz f osc = 14.7456 mhz u2x = 0 u2x = 1 u2x = 0 u2x = 1 u2x = 0 u2x = 1 ubrr error ubrr error ubrr error ubrr error ubrr error ubrr error 2400 207 0.2% 416 -0.1% 287 0.0% 575 0.0% 383 0.0% 767 0.0% 4800 103 0.2% 207 0.2% 143 0.0% 287 0.0% 191 0.0% 383 0.0% 9600 51 0.2% 103 0.2% 71 0.0% 143 0.0% 95 0.0% 191 0.0% 14.4k 34 -0.8% 68 0.6% 47 0.0% 95 0.0% 63 0.0% 127 0.0% 19.2k 25 0.2% 51 0.2% 35 0.0% 71 0.0% 47 0.0% 95 0.0% 28.8k 16 2.1% 34 -0.8% 23 0.0% 47 0.0% 31 0.0% 63 0.0% 38.4k 12 0.2% 25 0.2% 17 0.0% 35 0.0% 23 0.0% 47 0.0% 57.6k 8 -3.5% 16 2.1% 11 0.0% 23 0.0% 15 0.0% 31 0.0% 76.8k 6 -7.0% 12 0.2% 8 0.0% 17 0.0% 11 0.0% 23 0.0% 115.2k 3 8.5% 8 -3.5% 5 0.0% 11 0.0% 7 0.0% 15 0.0% 230.4k 1 8.5% 3 8.5% 2 0.0% 5 0.0% 3 0.0% 7 0.0% 250k 1 0.0% 3 0.0% 2 -7.8% 5 -7.8% 3 -7.8% 6 5.3% 0.5m 0 0.0% 1 0.0% ? ? 2 -7.8% 1 -7.8% 3 -7.8% 1m ? ? 0 0.0% ? ? ? ? 0 -7.8% 1 -7.8% max. (1) 0.5 mbps 1 mbps 691.2 kbps 1.3824 mbps 921.6 kbps 1.8432 mbps 1. ubrr = 0, error = 0.0% 194 2513k?avr?07/09 atmega162/v table 81. examples of ubrr settings for commonl y used oscillator frequencies (continued) baud rate (bps) f osc = 16.0000 mhz f osc = 18.4320 mhz f osc = 20.0000 mhz u2x = 0 u2x = 1 u2x = 0 u2x = 1 u2x = 0 u2x = 1 ubrr error ubrr error ubrr error ubrr error ubrr error ubrr error 2400 416 -0.1% 832 0.0% 479 0.0% 959 0.0% 520 0.0% 1041 0.0% 4800 207 0.2% 416 -0.1% 239 0.0% 479 0.0% 259 0.2% 520 0.0% 9600 103 0.2% 207 0.2% 119 0.0% 239 0.0% 129 0.2% 259 0.2% 14.4k 68 0.6% 138 -0.1% 79 0.0% 159 0.0% 86 -0.2% 173 -0.2% 19.2k 51 0.2% 103 0.2% 59 0.0% 119 0.0% 64 0.2% 129 0.2% 28.8k 34 -0.8% 68 0.6% 39 0.0% 79 0.0% 42 0.9% 86 -0.2% 38.4k 25 0.2% 51 0.2% 29 0.0% 59 0.0% 32 -1.4% 64 0.2% 57.6k 16 2.1% 34 -0.8% 19 0.0% 39 0.0% 21 -1.4% 42 0.9% 76.8k 12 0.2% 25 0.2% 14 0.0% 29 0.0% 15 1.7% 32 -1.4% 115.2k 8 -3.5% 16 2.1% 9 0.0% 19 0.0% 10 -1.4% 21 -1.4% 230.4k 3 8.5% 8 -3.5% 4 0.0% 9 0.0% 4 8.5% 10 -1.4% 250k 3 0.0% 7 0.0% 4 -7.8% 8 2.4% 4 0.0% 9 0.0% 0.5m 1 0.0% 3 0.0% ? ? 4 -7.8% ? ? 4 0.0% 1m 0 0.0% 1 0.0% ? ? ? ? ? ? ? ? max. (1) 1 mbps 2 mbps 1.152 mbps 2.3 04 mbps 1.25 mbps 2.5 mbps 1. ubrr = 0, error = 0.0% 195 2513k?avr?07/09 atmega162/v analog comparator the analog comparator compares the input values on the positive pin ain0 and negative pin ain1. when the voltage on the positive pin ain0 is higher than the voltage on the negative pin ain1, the analog comparator output, aco, is set. the comparator?s output can be set to trigger the timer/counter1 input capture function. in addition, the comparator can trigger a separate interrupt, exclusive to the analog comparator. th e user can select interrupt triggering on com- parator output rise, fall or toggle. a block diagram of the comparator and its surrounding logic is shown in figure 82 . figure 82. analog comparator block diagram (1) note: 1. refer to figure 1 on page 2 and table 32 on page 72 for analog comparator pin placement. analog comparator control and status register ? acsr ? bit 7 ? acd: analog comparator disable when this bit is written logic one , the power to the analog comparator is switched off. this bit can be set at any time to tu rn off the analog com parator. this will reduce power consumption in active and idle mode. when changing the acd bit, the analog comparator interrupt must be disabled by clearing the acie bit in acsr. otherwise an interrupt can occur when the bit is changed. ? bit 6 ? acbg: analog comparator bandgap select when this bit is set, a fixed bandgap reference vo ltage replaces the positive input to the analog comparator. when this bit is cleared, ain0 is ap plied to the positive input of the analog compar- ator. when the bandgap reference is used as input to the analog comparator, it will take a certain time for the voltage to stabilize. if not stibilized, the fi rst conversion may give a wrong value. see ?internal voltage reference? on page 52. ? bit 5 ? aco: analog comparator output the output of the analog comparator is synchronized and then directly connected to aco. the synchronization introduces a delay of 1 - 2 clock cycles. acbg bandgap reference bit 76543210 acd acbg aco aci acie acic acis1 acis0 acsr read/write r/w r/w r r/w r/w r/w r/w r/w initial value00n/a00000 196 2513k?avr?07/09 atmega162/v ? bit 4 ? aci: analog comparator interrupt flag this bit is set by hardware when a comparator output event triggers the interrupt mode defined by acis1 and acis0. the analog comparator interr upt routine is executed if the acie bit is set and the i-bit in sreg is set. aci is cleared by hardware when executing the corresponding inter- rupt handling vector. alternatively, aci is cleared by writing a logic one to the flag. ? bit 3 ? acie: analog comparator interrupt enable when the acie bit is written logic one and the i-bi t in the status register is set, the analog com- parator interrupt is activated. when written logic zero, the interrupt is disabled. ? bit 2 ? acic: analog comparator input capture enable when written logic one, this bit enables the input capture function in timer/counter1 to be trig- gered by the analog comparator. the comparator output is in this case directly connected to the input capture front-end logic, making the comp arator utilize the noise canceler and edge select features of the timer/counter1 input capture interrupt. when written logic zero, no connection between the analog comparator and the input capture function exists. to make the comparator trigger the timer/counter1 input capture interrupt, the ticie1 bit in the timer interrupt mask register (timsk) must be set. ? bits 1, 0 ? acis1, acis0: analog comparator interrupt mode select these bits determine which comparator events that trigger the analog comparator interrupt. the different settings are shown in table 82 . when changing the acis1/acis0 bits, the analog comparator interrupt must be disabled by clearing its interrupt enable bit in the acsr register. otherwise an interrupt can occur when the bits are changed. table 82. acis1/acis0 settings acis1 acis0 interrupt mode 0 0 comparator interrupt on output toggle. 01reserved 1 0 comparator interrupt on falling output edge. 1 1 comparator interrupt on rising output edge. 197 2513k?avr?07/09 atmega162/v jtag interface and on-chip debug system features ? jtag (ieee std. 1149.1 compliant) interface ? boundary-scan capabilities according to the ieee std. 1149.1 (jtag) standard ? debugger access to: ? all internal peripheral units ? internal and external ram ? the internal register file ? program counter ? eeprom and flash memories ? extensive on-chip debug support for break conditions, including ? avr break instruction ? break on change of program memory flow ? single step break ? program memory breakpoints on single address or address range ? data memory breakpoints on si ngle address or address range ? programming of flash, eeprom , fuses, and lock bits through the jtag interface ? on-chip debugging supported by avr studio ? overview the avr ieee std. 1149.1 compliant jtag interface can be used for ? testing pcbs by using the jtag boundary-scan capability. ? programming the non-volatile memories, fuses and lock bits. ? on-chip debugging. a brief description is given in the following se ctions. detailed descriptions for programming via the jtag interface, and using the boundary-scan chain can be found in the sections ?program- ming via the jtag interface? on page 250 and ?ieee 1149.1 (jtag) bo undary-scan? on page 204 , respectively. the on-chip debug support is considered being private jtag instructions, and distributed within atmel and to selected third party vendors only. figure 83 shows a block diagram of the jtag interface and the on-chip debug system. the tap controller is a state machine controlled by the tck and tms signals. the tap controller selects either the jtag instruction register or one of several data registers as the scan chain (shift register) between the tdi ? input and tdo ? output. the instruction register holds jtag instructions controlling the be havior of a data register. the id-register, bypass register, and the bou ndary-scan chain are the data registers used for board-level testing. the jtag programming interface (actually consisting of several physical and virtual data registers) is used for serial programming via the jtag interface. the internal scan chain and break point scan chain are used for on-chip debugging only. test access port ? tap the jtag interface is accessed through four of the avr?s pins. in jtag terminology, these pins constitute the test access port ? tap. these pins are: ? tms: test mode select. this pin is used for navigating through the tap-controller state machine. ? tck: test clock. jtag operation is synchronous to tck. ? tdi: test data in. serial input data to be shifted in to the instruction register or data register (scan chains). ? tdo: test data out. serial output data from instruction register or data register. 198 2513k?avr?07/09 atmega162/v the ieee std. 1149.1 also specifies an optional tap signal; trst ? test reset ? which is not provided. when the jtagen fuse is unprogrammed, these four tap pins are normal port pins and the tap controller is in reset. when programmed and the jtd bit in mcucsr is cleared, the tap input signals are internally pulled high and the jtag is enabled for boundary-scan and program- ming. in this case, the tap output pin (tdo) is left floating in states where the jtag tap controller is not shifting data, and must therefore be connected to a pull-up resistor or other hardware having pull-ups (for instance the tdi-input of the next device in the scan chain). the device is shipped with this fuse programmed. for the on-chip debug system, in addition to the jtag interface pins, the reset pin is moni- tored by the debugger to be able to detect external reset sources. the debugger can also pull the reset pin low to reset the whole system, assuming only open collectors on the reset line are used in the application. figure 83. block diagram tap controller tdi tdo tck tms flash memory avr cpu digital peripheral units jtag / avr core communication interface breakpoint unit flow control unit ocd status and control internal scan chain m u x instruction register id register bypass register jtag programming interface pc instruction address data breakpoint scan chain address decoder analog peripherial units i/o port 0 i/o port n boundary scan chain analog inputs control & clock lines device boundary 199 2513k?avr?07/09 atmega162/v figure 84. tap controller state diagram test-logic-reset run-test/idle shift-dr exit1-dr pause-dr exit2-dr update-dr select-ir scan capture-ir shift-ir exit1-ir pause-ir exit2-ir update-ir select-dr scan capture-dr 0 1 0 11 1 00 00 11 1 0 1 1 0 1 0 0 1 0 1 1 0 1 0 0 0 0 1 1 200 2513k?avr?07/09 atmega162/v tap controller the tap controller is a 16-state finite state machine that controls the operation of the boundary- scan circuitry, jtag programming circuitry, or on-chip debug system. the state transitions depicted in figure 84 depend on the signal present on tms (shown adjacent to each state tran- sition) at the time of the rising edge at tck. the initial state after a power-on reset is test- logic-reset. as a definition in this document, the lsb is shifted in and out first for all shift registers. assuming run-test/idle is the present state, a typical scenario for using the jtag interface is: ? at the tms input, apply the sequence 1, 1, 0, 0 at the rising edges of tck to enter the shift instruction register ? shift-ir state. while in this state, shift the four bits of the jtag instructions into the jtag instruction register from the tdi input at the rising edge of tck. the tms input must be held low during input of the 3 lsbs in order to remain in the shift-ir state. the msb of the instruction is shifted in when this state is left by setting tms high. while the instruction is shifted in from the tdi pin, the captured ir-state 0x01 is shifted out on the tdo pin. the jtag instruction selects a particular data register as path between tdi and tdo and controls the circuitry surrounding the selected data register. ? apply the tms sequence 1, 1, 0 to re-enter the run-test/idle state. the instruction is latched onto the parallel output from the shift register path in the update-ir state. the exit- ir, pause-ir, and exit2-ir states are onl y used for navigating the state machine. ? at the tms input, apply the sequence 1, 0, 0 at the rising edges of tck to enter the shift data register ? shift-dr state. while in this state, upload the selected data register (selected by the present jtag instruction in the jtag instruction register) from the tdi input at the rising edge of tck. in order to remain in the shift-dr state, the tms input must be held low during input of all bits except the msb. the msb of the data is shifted in when this state is left by setting tms high. while the data register is shifted in from the tdi pin, the parallel inputs to the data register captured in the capture-dr state is shifted out on the tdo pin. ? apply the tms sequence 1, 1, 0 to re-enter the run-test/idle state. if the selected data register has a latched parallel-output, the latching takes place in the update-dr state. the exit-dr, pause-dr, and exit2-dr states are only used for navigating the state machine. as shown in the state diagram, the run-test/idle state need not be entered between selecting jtag instruction and using data registers, and some jtag instructions may select certain functions to be performed in the run-test/idle, making it unsuitable as an idle state. note: independent of the initial state of the tap c ontroller, the test-logic-r eset state can always be entered by holding tms high for five tck clock periods. for detailed information on the jtag specification, refer to the literature listed in ?bibliography? on page 203 . using the boundary-scan chain a complete description of the boundary-sc an capabilities are gi ven in the section ?ieee 1149.1 (jtag) boundary-scan? on page 204 . 201 2513k?avr?07/09 atmega162/v using the on-chip debug system as shown in figure 83 , the hardware support for on-chi p debugging consists mainly of ? a scan chain on the interface between the internal avr cpu and the internal peripheral units ? break point unit ? communication interface between the cpu and jtag system all read or modify/write operations needed for implementing the debugger are done by applying avr instructions via the internal avr cpu scan chain. the cpu sends the result to an i/o memory mapped location which is part of the communication interface between the cpu and the jtag system. the break point unit implements break on change of program flow, single step break, two pro- gram memory break points, and two combined break points. together, the four break points can be configured as either: ? 4 single program memory break points ? 3 single program memory break point + 1 single data memory break point ? 2 single program memory break points + 2 single data memory break points ? 2 single program memory break points + 1 program memory break point with mask (?range break point?) ? 2 single program memory break points + 1 data memory break point with mask (?range break point?) a debugger, like the avr studio ? , may however use one or more of these resources for its inter- nal purpose, leaving less flexibility to the end-user. a list of the on-chip debug specific jtag instructions is given in ?on-chip debug specific jtag instructions? on page 202 . the jtagen fuse must be programmed to enable the jtag test access port. in addition, the ocden fuse must be programmed and no lock bits must be set for the on-chip debug system to work. as a security feature, the on-chip debug system is disabled when either of the lb1 or lb2 lock bits are set. otherwise, the on-chi p debug system would have provided a backdoor into a secu red device. the avr studio enables the user to fully contro l execution of programs on an avr device with on-chip debug capability, avr in- circuit emulator, or the built-i n avr instruction set simulator. avr studio supports source level execution of assembly programs assembled with atmel cor- poration?s avr assembler and c programs compiled with third party vendors? compilers. avr studio runs under microsoft ? windows ? 95/98/2000, windows nt ? , and windows xp ? . for a full description of the avr studio, please refer to the avr studio user guide . only high- lights are presented in this document. all necessary execution commands are available in avr studio, both on source level and on disassembly level. the user can execute the program, single step through the code either by tracing into or stepping over functions, step out of functions, place the cursor on a statement and execute until the statement is reached, stop th e execution, and reset the execution target. in addition, the user can have an unlimited number of code break points (using the break instruction) and up to two data memory break points, alternatively combined as a mask (range) break point. 202 2513k?avr?07/09 atmega162/v on-chip debug specific jtag instructions the on-chip debug support is considered being private jtag instructions, and distributed within atmel and to selected 3rd party vendors only. instruction opcodes are listed for reference. private0; 0x8 private jtag instruction for accessing on-chip debug system. private1; 0x9 private jtag instruction for accessing on-chip debug system. private2; 0xa private jtag instruction for accessing on-chip debug system. private3; 0xb private jtag instruction for accessing on-chip debug system. on-chip debug related register in i/o memory on-chip debug register ? ocdr the ocdr register provides a co mmunication channel from the running pr ogram in the micro- controller to the debugger. the cpu can transfer a byte to the debugger by writing to this location. at the same time, an in ternal flag; i/o debug register dirty ? idrd ? is set to indicate to the debugger that the register has been written. when the cpu reads the ocdr register the 7 lsb will be from the ocdr regi ster, while the msb is the idrd bit. the debugger clears the idrd bit when it has read the information. in some avr devices, this register is shared with a standard i/o location. in this case, the ocdr register can only be accessed if the ocden fuse is programmed, and the debugger enables access to the ocdr register. in all other cases, the standard i/o location is accessed. refer to the debugger documentation for further information on how to use this register. using the jtag programming capabilities programming of avr parts via jtag is performed via the 4-pin jtag port, tck, tms, tdi and tdo. these are the only pins that need to be controlled/observed to perform jtag program- ming (in addition to power pins). it is not requi red to apply 12v externally. the jtagen fuse must be programmed and the jtd bit in the mcus r register must be cleared to enable the jtag test access port. the jtag programmi ng capability supports: ? flash programming and verifying. ? eeprom programming and verifying. ? fuse programming and verifying. ? lock bit programming and verifying. the lock bit security is exactly as in parallel programming mode. if the lock bits lb1 or lb2 are programmed, the ocden fuse cannot be programmed unless first doing a chip erase. this is a security feature that ensures no backdoor exists for reading out the content of a secured device. the details on programming through the jtag interface and programming specific jtag instructions are given in the section ?programming via the jtag interface? on page 250 . bit 7 6543210 msb/idrd lsb ocdr read/write r/w r/w r/w r/w r/w r/w r/w r/w initial value 0 0 0 0 0 0 0 0 203 2513k?avr?07/09 atmega162/v bibliography for more information about general boundary-scan, the following literature can be consulted: ? ieee: ieee std. 1149.1-1990. ieee standard test access port and boundary-scan architecture, ieee, 1993 ? colin maunder: the board designers guide to testable logic circuits, addison-wesley, 1992 204 2513k?avr?07/09 atmega162/v ieee 1149.1 (jtag) boundary-scan features ? jtag (ieee std. 1149.1 compliant) interface ? boundary-scan capabilities acco rding to the jtag standard ? full scan of all port functions as well as analog circuitry havi ng off-chip connections ? supports the optional idcode instruction ? additional public avr_reset instruction to reset the avr system overview the boundary-scan chain has the capability of drivin g and observing the logi c levels on the digi- tal i/o pins, as well as the boundary between digi tal and analog logic for analog circuitry having off-chip connections. at system level, all ics hav ing jtag capabilities ar e connected serially by the tdi/tdo signals to form a long shift register. an external controller sets up the devices to drive values at their output pins, and observe the input values received from other devices. the controller compares the received data with the expected result. in this way, boundary-scan pro- vides a mechanism for testing interconnections and integrity of components on printed circuits boards by using the four tap signals only. the four ieee 1149.1 defined mandatory jtag in structions idcode, bypass, sample/pre- load, and extest, as well as the avr specif ic public jtag instruction avr_reset can be used for testing the print ed circuit board. initial scanning of the data register path will show the id-code of the device, since idcode is the default jtag instruction. it may be desirable to have the avr device in reset during test mode. if not reset, inputs to the device may be determined by the scan operations, and the internal software may be in an undetermined state when exiting the test mode. entering reset, the outputs of any po rt pin will instantly en ter the high impedance state, making the highz instruction redundant. if needed, the bypass instruction can be issued to make the shortest possible scan c hain through the device. the device can be set in the reset state either by pulling the external reset pin low, or issuing the avr_reset instruction with appropriate setting of the reset data register. the extest instruction is used for sampling external pins and loading output pins with data. the data from the output latch will be driven out on the pins as soon as the extest instruction is loaded into the jtag ir-register. therefore, the sample/preload should also be used for setting initial values to the scan ring, to avoid damaging the board when issuing the extest instruction for the first time. sample/preload c an also be used for taking a snapshot of the external pins during normal operation of the part. the jtagen fuse must be programmed and the jtd bit in the i/o register mcucsr must be cleared to enable the jtag test access port. when using the jtag interface for boundary-scan, using a jtag tck clock frequency higher than the internal chip frequency is possible. the chip clock is not required to run. 205 2513k?avr?07/09 atmega162/v data registers the data registers relevant for boundary-scan operations are: ? bypass register ? device identification register ? reset register ? boundary-scan chain bypass register the bypass register consists of a single shift register stage. when the bypass register is selected as path between tdi and tdo, the register is reset to 0 when leaving the capture-dr controller state. the bypass register can be used to shorten the scan chain on a system when the other devices are to be tested. device identification register figure 85 shows the structure of the de vice identification register. figure 85. the format of the device identification register version version is a 4-bit number identifying the revision of the component. the jtag version number follows the revision of the device. revision a is 0x0, revision b is 0x1 and so on. part number the part number is a 16-bit code identifying the component. the jtag part number for atmega162 is listed in table 83 . manufacturer id the manufacturer id is a 11-bit code identifying the manufacturer. the jtag manufacturer id for atmel is listed in table 84 . reset register the reset register is a test data register used to reset the part. since the avr tri-states port pins when reset, the reset register can also replace the function of the unimplemented optional jtag instruction highz. a high value in the reset register corresponds to pulling the external reset low. the part is reset as long as there is a high value present in the reset register. depending on the fuse set- tings for the clock options, the part will remain reset for a reset time-o ut period (refer to ?clock sources? on page 36 ) after releasing the reset register. the output from this data register is not latched, so the reset will take place immediately, as shown in figure 86 . msb lsb bit 31 28 27 12 11 1 0 device id version part number manufacturer id 1 4 bits 16 bits 11 bits 1 bit table 83. avr jtag part number part number jtag part number (hex) atmega162 0x9404 table 84. manufacturer id manufacturer jtag man. id (hex) atmel 0x01f 206 2513k?avr?07/09 atmega162/v figure 86. reset register boundary-scan chain the boundary-scan chain has the capability of driv ing and observing the lo gic levels on the dig- ital i/o pins, as well as the boundary between di gital and analog logic for analog circuitry having off-chip connections. see ?boundary-scan chain? on page 208 for a complete description. boundary-scan specific jtag instructions the instruction register is 4-bit wide, suppor ting up to 16 instructions. listed below are the jtag instructions useful for boundary-scan operation. note that the optional highz instruction is not implemented, but all outputs with tri-stat e capability can be set in high-impedant state by using the avr_reset instruction, since the initial state for all port pins is tri-state. as a definition in this datasheet, the lsb is shifted in and out first for all shift registers. the opcode for each instruction is shown behind the instruction name in hex format. the text describes which data register is selected as path between tdi and tdo for each instruction. extest; 0x0 mandatory jtag instruction for selecting the boundary-scan chain as data register for testing circuitry external to the avr package. for port- pins, pull-up disable, output control, output data, and input data are all accessible in the scan chain. for analog circuits having off-chip connections, the interface between the analog and th e digital logic is in the scan chain. the con- tents of the latched outputs of the boundary-scan chain is driven out as soon as the jtag ir- register is loaded with the extest instruction. the active states are: ? capture-dr: data on the external pins are sampled into the boundary-scan chain. ? shift-dr: the internal scan chain is shifted by the tck input. ? update-dr: data from the scan chain is applied to output pins. dq from tdi clockdr avr_reset to tdo from other internal and external reset sources internal reset 207 2513k?avr?07/09 atmega162/v idcode; 0x1 optional jtag instruction selecting the 32-bit id-register as data register. the id-register con- sists of a version number, a device number and the manufacturer code chosen by jedec. this is the default instruction after power-up. the active states are: ? capture-dr: data in the idcode register is sampled into the boundary-scan chain. ? shift-dr: the idcode scan chai n is shifted by the tck input. sample_preload; 0x2 mandatory jtag instruction for preloading the output latches and taking a snapshot of the input/output pins without affecting the system operation. however, the output latches are not connected to the pins. the boundary-scan chain is selected as data register. the active states are: ? capture-dr: data on the external pins are sampled into the boundary-scan chain. ? shift-dr: the boundary-scan chain is shifted by the tck input. ? update-dr: data from the boundary-scan chain is applied to the output latches. however, the output latches are not connected to the pins. avr_reset; 0xc the avr specific public jtag instruction for forcing the avr device into the reset mode or releasing the jtag reset source. the tap controller is not reset by this instruction. the one bit reset register is selected as da ta register. note that the reset will be active as long as there is a logic 'one' in the reset chain. the output from this chain is not latched. the active states are: ? shift-dr: the reset register is shifted by the tck input. bypass; 0xf mandatory jtag instruction selecting the bypass register for data register. the active states are: ? capture-dr: loads a logic ?0? into the bypass register. ? shift-dr: the bypass register cell between tdi and tdo is shifted. boundary-scan related register in i/o memory mcu control and status register ? mcucsr the mcu control and status register contains control bits for general mcu functions, and pro- vides information on which reset source caused an mcu reset. ? bit 7 ? jtd: jtag interface disable when this bit is zero, the jtag interface is ena bled if the jtagen fuse is programmed. if this bit is one, the jtag interface is disabled. in or der to avoid unintentional disabling or enabling of the jtag interface, a timed sequence must be followed when changing this bit: the application software must write this bit to the desired value twice within four cycles to change its value. if the jtag interface is left unconnected to ot her jtag circuitry, the jtd bit should be set to one. the reason for this is to avoid static current at the tdo pin in the jtag interface. bit 76543210 jtd ? sm2 jtrf wdrf borf extrf porf mcucsr read/write r/w r/w r r/w r/w r/w r/w r/w initial value 0 0 0 see bit description 208 2513k?avr?07/09 atmega162/v ? bit 4 ? jtrf: jtag reset flag this bit is set if a reset is being caused by a logic one in the jtag reset register selected by the jtag instruction avr_reset. this bit is rese t by a power-on reset, or by writing a logic zero to the flag. boundary-scan chain the boundary-scan chain has the capability of driv ing and observing the lo gic levels on the dig- ital i/o pins, as well as the boundary between di gital and analog logic for analog circuitry having off-chip connection. scanning the digital port pins figure 87 shows the boundary-scan cell for a bi-dir ectional port pin with pull-up function. the cell consists of a standard boundary-scan cell for the pull-up enable ? puexn ? function, and a bi-directional pin cell that combines the three signals output control ? ocxn, output data ? odxn, and input data ? idxn, into only a two-stage shift register. the port and pin indexes are not used in the following description the boundary-scan logic is not included in the figures in the datasheet. figure 88 shows a sim- ple digital port pin as described in the section ?i/o-ports? on page 63 . the boundary-scan details from figure 87 replaces the dashed box in figure 88 . when no alternate port function is present, t he input data ? id ? corresponds to the pinxn reg- ister value (but id has no synchronizer), output data corresponds to the port register, output control corresponds to the data direction ? dd register, and the pull-up enable ? puexn ? cor- responds to logic expression pud ddxn portxn. digital alternate port functions are connected outside the dotted box in figure 88 to make the scan chain read the actual pin value. for analog function, there is a direct connection from the external pin to the analog circuit, and a scan ch ain is inserted on the interface between the digi- tal logic and the analog circuitry. 209 2513k?avr?07/09 atmega162/v figure 87. boundary-scan cell for bi-directional port pin with pull-up function. dq dq g 0 1 0 1 dq dq g 0 1 0 1 0 1 0 1 dq dq g 0 1 port pin (pxn) vcc extest to next cell shiftdr output control (oc) pullup enable (pue) output data (od) input data (id) from last cell updatedr clockdr ff2 ld2 ff1 ld1 ld0 ff0 210 2513k?avr?07/09 atmega162/v figure 88. general port pin schematic diagram scanning the reset pin the reset pin accepts 5v active low logic fo r standard reset operation, and 12v active high logic for high voltage parallel programming. an observe-only cell as shown in figure 89 is inserted both for the 5v reset signal; rstt, and the 12v reset signal; rsthv. figure 89. observe-only cell clk rpx rrx wrx rdx wdx pud synchronizer wdx: write ddrx wrx: write portx rrx: read portx register rpx: read portx pin pud: pullup disable clk : i/o clock rdx: read ddrx d l q q reset reset q q d q q d clr portxn q q d clr ddxn pinxn data b u s sleep sleep: sleep control pxn i/o i/o see boundary-scan description for details! puexn ocxn odxn idxn puexn: pullup enable for pin pxn ocxn: output control for pin pxn odxn: output data to pin pxn idxn: input data from pin pxn 0 1 dq from previous cell clockdr shiftdr to next cell from system pin to system logic ff1 211 2513k?avr?07/09 atmega162/v scanning the clock pins the avr devices have many clock options selectable by fuses. these are: internal rc oscilla- tor, external clock, (high frequency) crystal oscillator, low frequency crystal oscillator, and ceramic resonator. figure 90 shows how each oscillator with external connection is supported in the scan chain. the enable signal is supported with a general bo undary-scan cell, while the oscillator/clock out- put is attached to an observe-only cell. in additi on to the main clock, the timer oscillator is scanned in the same way. the output from the internal rc oscillator is not scanned, as this oscillator does not have external connections. figure 90. boundary-scan cells for o scillators and clock options table 85 summaries the scan registers for the ex ternal clock pin xta l1, oscillators with xtal1/xtal2 connections as we ll as 32 khz timer oscillator. notes: 1. do not enable more than one clock source as main clock at a time. 2. scanning an oscillator output gives unpredictable results as there is a frequency drift between the internal oscillator and the jtag tck clock. if possible, scanning an external clock is preferred. 3. the clock configuration is programmed by fuses. as a fuse is not changed run-time, the clock configuration is considered fixed for a given app lication. the user is advised to scan the same clock option as to be used in the final system. the enable signals are supported in the scan chain because the system logic c an disable clock options in sl eep modes, thereby disconnect- ing the oscillator pins from the scan path if not provided. the intcap selection is not supported in the scan-chain, so the boundar y scan chain can not make a xtal oscillator requiring internal capacitors to run unless the fuses are correctly programmed. table 85. scan signals for the oscillator (1)(2)(3) enable signal scanned clock line clock option scanned clock line when not used extclken extclk (xtal1) external clock 0 oscon oscck external crystal external ceramic resonator 0 osc32en osc32ck low freq. external crystal 0 toskon tosck 32 khz timer oscillator 0 0 1 dq from previous cell clockdr shiftdr to next cell to system logic ff1 0 1 dq dq g 0 1 from previous cell clockdr updatedr shiftdr to next cell extest from digital logic xtal1/tosc1 xtal2/tosc2 oscillator enable output 212 2513k?avr?07/09 atmega162/v scanning the analog comparator the relevant comparator signals re garding boundary-scan are shown in figure 91 . the bound- ary-scan cell from figure 92 is attached to each of these signals. the signals are described in table 86 . the comparator need not be used for pure connectivity testing, since all analog inputs are shared with a digital port pin as well. figure 91. analog comparator figure 92. general boundary-scan cell used for signals for comparator acbg bandgap reference ac_idle aco 0 1 dq dq g 0 1 from previous cell clockdr updatedr shiftdr to next cell extest to snalog circuitry/ to digital logic from digital logic/ from analog ciruitry 213 2513k?avr?07/09 atmega162/v atmega162 boundary-scan order table 87 shows the scan order between tdi and tdo when the boundary-scan chain is selected as data path. bit 0 is the lsb; the first bit scanned in, and the first bit scanned out. the scan order follows the pinout order as far as possible. therefore, the bits of port a and port e is scanned in the opposite bit order of the other ports. exceptions from the rules are the scan chains for the analog circuits, which constitute th e most significant bits of the scan chain regard- less of which physical pin they are connected to. in figure 87 , pxn. data corresponds to ff0, pxn. control corresponds to ff1, and pxn. pullup_enable corresponds to ff2. bit 4, 5, 6, and 7of port c is not in the scan chain, since these pins constitute the tap pins when the jtag is enabled. table 86. boundary-scan signals for the analog comparator signal name direction as seen from the comparator description recommended input when not in use output values when recommended inputs are used ac_idle input turns off analog comparator when true 1 depends upon c code being executed aco output analog comparator output will become input to c code being executed 0 acbg input bandgap reference enable 0 depends upon c code being executed table 87. atmega162 boundary-scan order bit number signal name module 105 ac_idle comparator 104 aco 103 acbg 102 pb0.data port b 101 pb0.control 100 pb0.pullup_enable 99 pb1.data 98 pb1.control 97 pb1.pullup_enable 96 pb2.data 95 pb2.control 94 pb2.pullup_enable 93 pb3.data 92 pb3.control 91 pb3.pullup_enable 90 pb4.data 89 pb4.control 88 pb4.pullup_enable 214 2513k?avr?07/09 atmega162/v 87 pb5.data port b 86 pb5.control 85 pb5.pullup_enable 84 pb6.data 83 pb6.control 82 pb6.pullup_enable 81 pb7.data 80 pb7.control 79 pb7.pullup_enable 78 rstt reset logic (observe-only) 77 rsthv 76 tosc 32 khz timer oscillator 75 toscon 74 pd0.data port d 73 pd0.control 72 pd0.pullup_enable 71 pd1.data 70 pd1.control 69 pd1.pullup_enable 68 pd2.data 67 pd2.control 66 pd2.pullup_enable 65 pd3.data 64 pd3.control 63 pd3.pullup_enable 62 pd4.data 61 pd4.control 60 pd4.pullup_enable 59 pd5.data port d 58 pd5.control 57 pd5.pullup_enable 56 pd6.data 55 pd6.control 54 pd6.pullup_enable 53 pd7.data 52 pd7.control table 87. atmega162 boundary-scan order (continued) bit number signal name module 215 2513k?avr?07/09 atmega162/v 51 pd7.pullup_enable port d 50 extclken enable si gnals for main clock/oscillators 49 oscon 48 osc32en 47 extclk (xtal1) clock input and oscillators for the main clock (observe- only) 46 oscck 45 osc32ck 44 pc0.data port c 43 pc0.control 42 pc0.pullup_enable 41 pc1.data 40 pc1.control 39 pc1.pullup_enable 38 pc2.data 37 pc2.control 36 pc2.pullup_enable 35 pc3.data 34 pc3.control 33 pc3.pullup_enable 32 pe2.data port e 31 pe2.control 30 pe2.pullup_enable 29 pe1.data 28 pe1.control 27 pe1.pullup_enable 26 pe0.data 25 pe0.control 24 pe0.pullup_enable 23 pa7.data port a 22 pa7.control 21 pa7.pullup_enable 20 pa6.data 19 pa6.control 18 pa6.pullup_enable 17 pa5.data 16 pa5.control table 87. atmega162 boundary-scan order (continued) bit number signal name module 216 2513k?avr?07/09 atmega162/v note: 1. private_signal1 should always be scanned in as zero. boundary-scan description language files boundary-scan description language (bsdl) files describe boundary-scan capable devices in a standard format used by automated test-generation software. the order and function of bits in the boundary-scan data register are included in this description. a bsdl file for atmega162 is available. 15 pa5.pullup_enable port a 14 pa4.data 13 pa4.control 12 pa4.pullup_enable 11 pa3.data 10 pa3.control 9 pa3.pullup_enable 8pa2.data 7 pa2.control 6 pa2.pullup_enable 5pa1.data 4 pa1.control 3 pa1.pullup_enable 2pa0.data 1 pa0.control 0 pa0.pullup_enable table 87. atmega162 boundary-scan order (continued) bit number signal name module 217 2513k?avr?07/09 atmega162/v boot loader support ? read- while-write self- programming the boot loader support provides a real read-while-write self-programming mechanism for downloading and uploading program code by the m cu itself. this feature a llows flexible applica- tion software updates controlled by the mcu using a flash-resident boot loader program. the boot loader program can use any available data interface and associated protocol to read code and write (program) that code into the flash memory, or read the code from the program mem- ory. the program code within the boot loader section has the capability to write into the entire flash, including the boot loader memory. the b oot loader can thus even modify itself, and it can also erase itself from the code if the feature is not needed anymore. the size of the boot loader memory is configurable with fuses and the boot loader has two separate sets of boot lock bits which can be set indepen dently. this gives the user a uniq ue flexibility to select differ- ent levels of protection. features ? read-while-write self-programming ? flexible boot memory size ? high security (separate boot lock bits for a flexible protection) ? separate fuse to select reset vector ? optimized page (1) size ? code efficien t algorithm ? efficient read-mod ify-write support note: 1. a page is a section in the flash consisting of several bytes (see table 105 on page 236 ) used during programming. the page organization does not affect normal operation. application and boot loader flash sections the flash memory is organized in two main sections, the application section and the boot loader section (see figure 94 ). the size of the different sections is configured by the bootsz fuses as shown in table 93 on page 228 and figure 94 . these two sections can have different level of protection since they have different sets of lock bits. application section the application section is the section of the flash that is used for storing the application code. the protection level for the application section can be selected by the application boot lock bits (boot lock bits 0), see table 89 on page 220 . the application section can never store any boot loader code since the spm instruction is disabled when executed from the application section. bls ? boot loader section while the application section is used for storing the application code, the the boot loader soft- ware must be located in the bls since the spm instruction can initiate a programming when executing from the bls only. the spm instruct ion can access the entire flash, including the bls itself. the protection level for the boot loader section can be selected by the boot loader lock bits (boot lock bits 1), see table 90 on page 220 . read-while-write and no read- while-write flash sections whether the cpu supports read-while-write or if the cpu is halted during a boot loader soft- ware update is dependent on which address that is being programmed. in addition to the two sections that are configurable by the bootsz fuses as described above, the flash is also divided into two fixed sections, the read-whi le-write (rww) section and the no read-while- write (nrww) section. the limit between the rww- and nrww sections is given in table 94 on page 229 and figure 94 on page 219 . the main difference between the two sections is: ? when erasing or writing a page located inside the rww section, the nrww section can be read during the operation. ? when erasing or writing a page located inside the nrww section, the cpu is halted during the entire operation. note that the user software can never read any code that is located inside the rww section dur- ing a boot loader software operation. the syntax ?read-while-write section? refers to which section that is being programmed (erased or written), not which section that actually is being read during a boot loader software update. 218 2513k?avr?07/09 atmega162/v rww ? read-while- write section if a boot loader software update is programming a page inside the rww section, it is possible to read code from the flash, but only code that is located in the nrww section. during an ongo- ing programming, the software must ensure that the rww section never is being read. if the user software is trying to read code that is located inside the rww section (i.e., by a call/jmp/lpm or an interrupt) during programming, the software might end up in an unknown state. to avoid this, the interrupts should either be disabled or moved to the boot loader sec- tion. the boot loader section is always located in the nrww section. the rww section busy bit (rwwsb) in the store program memory cont rol register (spmcr) will be read as logical one as long as the rww section is blocked for reading. after a programming is completed, the rwwsb must be cleared by software before reading code located in the rww section. see ?store program memory control register ? spmcr? on page 221. for details on how to clear rwwsb. nrww ? no read- while-write section the code located in the nrww section can be read when the boot loader software is updating a page in the rww section. when the boot loader code updates the nrww section, the cpu is halted during the entire page erase or page write operation. figure 93. read-while-write vs. no read-while-write table 88. read-while-write features which section does the z- pointer address during the programming? which section can be read during programming? is the cpu halted? read-while- write supported? rww section nrww section no yes nrww section none yes no read-while-write (rww) section no read-while-write (nrww) section z-pointer addresses rww section z-pointer addresses nrww section cpu is halted during the operation code located in nrww section can be read during the operation 219 2513k?avr?07/09 atmega162/v figure 94. memory sections (1) note: 1. the parameters are given in table 93 on page 228 . boot loader lock bits if no boot loader capability is n eeded, the entire flash is available for application code. the boot loader has two separate sets of boot lock bits which can be set independently. this gives the user a unique flexibility to sele ct different levels of protection. the user can select: ? to protect the entire flash from a software update by the mcu ? to protect only the boot loader flash section from a software update by the mcu ? to protect only the application flash section from a software update by the mcu ? allow software update in the entire flash see table 89 and table 90 for further details. the boot lock bits can be set in software and in serial or parallel programming mode, but they can be cleared by a chip erase command only. the general write lock (lock bit mode 2) does not control the programming of the flash mem- 0x0000 flashend program memory bootsz = '11' application flash section boot loader flash section flashend program memory bootsz = '10' 0x0000 program memory bootsz = '01' program memory bootsz = '00' application flash section boot loader flash section 0x0000 flashend application flash section flashend end rww start nrww application flash section boot loader flash section boot loader flash section end rww start nrww end rww start nrww 0x0000 end rww, end application start nrww, start boot loader application flash section application flash section application flash section read-while-write section no read-while-write section read-while-write section no read-while-write section read while write section no read while write section read-while-write section no read-while-write section end application start boot loader end application start boot loader end application start boot loader 220 2513k?avr?07/09 atmega162/v ory by spm instruction. similarly, the general read/write lock (lock bit mode 1) does not control reading nor writing by lpm/spm, if it is attempted. note: 1. ?1? means unprogrammed, ?0? means programmed note: 1. ?1? means unprogrammed, ?0? means programmed table 89. boot lock bit0 protection modes (application section) (1) blb0 mode blb02 blb01 protection 111 no restrictions for spm or lpm accessing the application section. 2 1 0 spm is not allowed to write to the application section. 300 spm is not allowed to write to the application section, and lpm executing from the boot loader section is not allowed to read from the application section. if interrupt vectors are placed in the boot loader section, interrupts are disabled while executing from the application section. 401 lpm executing from the boot loader section is not allowed to read from the application section. if interrupt vectors are placed in the boot loader section, interrupts are disabled while executing from the application section. table 90. boot lock bit1 protection modes (boot loader section) (1) blb1 mode blb12 blb11 protection 111 no restrictions for spm or lpm accessing the boot loader section. 2 1 0 spm is not allowed to write to the boot loader section. 300 spm is not allowed to write to the boot loader section, and lpm executing from the application section is not allowed to read from the boot loader section. if interrupt vectors are placed in the application section, interrupts are disabled while executing from the boot loader section. 401 lpm executing from the application section is not allowed to read from the boot loader se ction. if interrupt vectors are placed in the application section, interrupts are disabled while executing from the boot loader section. 221 2513k?avr?07/09 atmega162/v entering the boot loader program entering the boot loader takes place by a jump or call from the application program. this may be initiated by a trigger such as a command received via usart, or spi interface. alternatively, the boot reset fuse can be programmed so that the reset vector is pointing to the boot flash start address after a reset. in this case, the boot loader is started after a reset. after the applica- tion code is loaded, the program can start execut ing the application code. note that the fuses cannot be changed by the mcu itself. this means that once the boot reset fuse is pro- grammed, the reset vector will always point to the boot loader reset and the fuse can only be changed through the serial or parallel programming interface. note: 1. ?1? means unprogrammed, ?0? means programmed store program memory control register ? spmcr the store program memory control register contains the control bits needed to control the boot loader operations. ? bit 7 ? spmie: spm interrupt enable when the spmie bit is written to one, and the i-bit in the status register is set (one), the spm ready interrupt will be enabled. the spm ready in terrupt will be ex ecuted as long as the spmen bit in the spmcr register is cleared. ? bit 6 ? rwwsb: read-while-write section busy when a self-programming (page erase or page write) operation to the rww section is initi- ated, the rwwsb will be set (one ) by hardware. when the rwws b bit is set, the rww section cannot be accessed. the rwwsb bit will be cleared if the rwwsre bit is written to one after a self-programming operation is completed. alte rnatively the rwwsb bit will automatically be cleared if a page load operation is initiated. ? bit 5 ? res: reserved bit this bit is a reserved bit in the atmega162 and always read as zero. ? bit 4 ? rwwsre: read-while-write section read enable when programming (page erase or page write) to the rww section, the rww section is blocked for reading (the rwwsb will be set by hardware). to re-enable the rww section, the user software must wait unt il the programming is complet ed (spmen will be cl eared). then, if the rwwsre bit is written to one at the same time as spmen, the next spm instruction within four clock cycles re-enables the rww secti on. the rww section cannot be re-enabled while the flash is busy with a page erase or a page wr ite (spmen is set). if the rwwsre bit is writ- ten while the flash is being loaded, the flas h load operation will abort and the data loaded will be lost. table 91. boot reset fuse (1) bootrst reset address 1 reset vector = application reset (address 0x0000). 0 reset vector = boot loader reset (see table 93 on page 228 ). bit 765 4 3210 spmie rwwsb ? rwwsre blbset pgwrt pgers spmen spmcr read/write r/w r r r/w r/w r/w r/w r/w initial value 0 0 0 0 0 0 0 0 222 2513k?avr?07/09 atmega162/v ? bit 3 ? blbset: boot lock bit set if this bit is written to one at the same time as spmen, the next spm instruction within four clock cycles sets boot lock bits, according to the data in r0. the data in r1 and the address in the z- pointer are ignored. the blbset bit will autom atically be cleared upon completion of the lock bit set, or if no spm instruction is executed within four clock cycles. an lpm instruction within thre e cycles after blbset and spmen are set in the spmcr regis- ter, will read either the lock bits or the fuse bits (depending on z0 in the z-pointer) into the destination register. see ?reading the fuse and lock bits from software? on page 225 for details. ? bit 2 ? pgwrt: page write if this bit is written to one at the same time as spmen, the next spm instruction within four clock cycles executes page write, with the data stored in the temporary buffer. the page address is taken from the high part of the z-pointer. the data in r1 and r0 are ignored. the pgwrt bit will auto?clear upon completion of a page write, or if no spm inst ruction is executed within four clock cycles. the cpu is halted during the ent ire page write operation if the nrww section is addressed. ? bit 1 ? pgers: page erase if this bit is written to one at the same time as spmen, the next spm instruction within four clock cycles executes page erase. the page address is taken from the high part of the z-pointer. the data in r1 and r0 are ignored. the pgers bi t will auto-clear upon comp letion of a page erase, or if no spm instruction is executed within four clock cycles. the cpu is halted during the entire page write operation if the nrww section is addressed. ? bit 0 ? spmen: store program memory enable this bit enables the spm instruction for the next four clock cycles. if written to one together with either rwwsre, blbset, pgwrt? or pgers, t he following spm instruction will have a spe- cial meaning, see description abo ve. if only spmen is written, the following spm instruction will store the value in r1:r0 in the temporary page buffer addressed by the z-pointer. the lsb of the z-pointer is ignored. the spmen bit will aut o-clear upon completion of an spm instruction, or if no spm instruction is executed within four clock cycles. during page erase and page write, the spmen bit remains high until the operation is completed. writing any other combination than ?10001?, ?01001?, ?00101?, ?00011? or ?00001? in the lower five bits will have no effect. 223 2513k?avr?07/09 atmega162/v addressing the flash during self- programming the z-pointer is used to address the spm commands. since the flash is organized in pages (see table 105 on page 236 ), the program counter can be treated as having two different sections. one sect ion, consisting of the least significant bits, is addressing the words within a page, while the most significant bits are addressing the pages. this is shown in figure 95 . note that the page erase and page write operations are addressed independently. therefore it is of major importance that the boot loader software addresses the same page in both the page erase and page write operation. once a programming operation is initiated, the address is latched and the z-pointer can be used for other operations. the only spm operation that does not use the z-pointer is setting the boot loader lock bits. the content of the z-pointer is ignored and will have no effect on the operation. the lpm instruction does also use the z-pointer to store the address. since this instruction addresses the flash byte-by-byte, also the lsb (bit z0) of the z-pointer is used. figure 95. addressing the flash during spm (1) notes: 1. the different variables used in figure 95 are listed in table 95 on page 230 . 2. pcpage and pcword are listed in table 105 on page 236 . bit 151413121110 9 8 zh (r31) z15 z14 z13 z12 z11 z10 z9 z8 zl (r30) z7z6z5z4z3z2z1z0 76543210 program memory 0 1 15 z - register bit 0 zpagemsb word address within a page page address within the flash zpcmsb instruction word page pcword[pagemsb:0]: 00 01 02 pageend page pcword pcpage pcmsb pagemsb program counter 224 2513k?avr?07/09 atmega162/v self-programming the flash the program memory is updated in a page by page fashion. before programming a page with the data stored in the temporary page buffer, the page must be erased. the temporary page buf- fer is filled one word at a time using spm and the buffer can be filled either before the page erase command or between a page erase and a page write operation: alternative 1, fill the bu ffer before a page erase ? fill temporary page buffer ? perform a page erase ? perform a page write alternative 2, fill the bu ffer after page erase ? perform a page erase ? fill temporary page buffer ? perform a page write if only a part of the page needs to be changed, the rest of the page must be stored (for example in the temporary page buffer) before the erase, and then be rewritten. when using alternative 1, the boot loader provides an effective read-modify-write feature which allows the user software to first read the page, do the necessary changes, and then write back the modified data. if alter- native 2 is used, it is not possible to read the old data while loading since the page is already erased. the temporary page buffer can be accessed in a random sequence. it is essential that the page address used in both the page erase and page write operation is addressing the same page. see ?simple assembly code example for a boot loader? on page 227 for an assembly code example. performing page erase by spm to execute page erase, set up the address in the z-pointer, write ?x0000011? to spmcr and execute spm within four clock cycles after wr iting spmcr. the data in r1 and r0 is ignored. the page address must be written to pcpage in the z-register. other bits in the z-pointer will be ignored during this operation. ? page erase to the rww section: the nrww section can be read during the page erase. ? page erase to the nrww section: the cpu is halted during the operation. filling the temporary buffer (page loading) to write an instruction word, set up the address in the z-pointer and data in r1:r0, write ?00000001? to spmcr and execute spm within four clock cycles after writing spmcr. the con- tent of pcword in the z-register is used to address the data in the temporary buffer. the temporary buffer will auto-erase after a page write operation or by writing the rwwsre bit in spmcr. it is also erased after a system reset. no te that it is not possible to write more than one time to each address without erasing the temporary buffer. note: if the eeprom is written in the middle of an spm page load operation, all data loaded will be lost. performing a page write to execute page write, set up the address in the z-pointer, write ?x0000101? to spmcr and execute spm within four clock cycles after wr iting spmcr. the data in r1 and r0 is ignored. the page address must be written to pcpage. other bits in the z-pointer must be written zero during this operation. ? page write to the rww section: the nrww section can be read during the page write. ? page write to the nrww section: the cpu is halted during the operation. 225 2513k?avr?07/09 atmega162/v using the spm interrupt if the spm interrupt is en abled, the spm interrupt will genera te a constant in terrupt when the spmen bit in spmcr is cleared. this means t hat the interrupt can be used instead of polling the spmcr register in software. when using the spm interrupt, the interrupt vectors should be moved to the bls section to avoid that an in terrupt is accessing the rww section when it is blocked for reading. how to move the interrupts is described in ?interrupts? on page 57 . consideration while updating bls special care must be taken if the user allows the boot loader section to be updated by leaving boot lock bit11 unprogrammed. an accidental write to the boot loader itself can corrupt the entire boot loader, and further software updates might be impossible. if it is not necessary to change the boot loader software itself, it is recommended to program the boot lock bit11 to protect the boot loader software from any internal software changes. prevent reading the rww section during self-programming during self-programming (either page erase or page write), the rww section is always blocked for reading. the user software itself must prevent that this section is addressed during the self programming operation. the rwwsb in the spmcr will be set as long as the rww section is busy. during self-programming the interrupt vector table should be moved to the bls as described in ?interrupts? on page 57 , or the interrupts must be disabled. before addressing the rww section after the programming is completed, the user software must clear the rwwsb by writing the rwwsre. see ?simple assembly code example for a boot loader? on page 227 for an example. setting the boot loader lock bits by spm to set the boot loader lock bits, write the desired data to r0, write ?x0001001? to spmcr and execute spm within four clock cycles after writing spmcr. the only accessible lock bits are the boot lock bits that may prevent the applic ation and boot loader section from any software update by the mcu. see table 89 and table 90 for how the different settings of the boot loader bits affect the flash access. if bits 5..2 in r0 are cleared (zero), the corresponding boot lock bit will be programmed if an spm instruction is executed within four cy cles after blbset and spmen are set in spmcr. the z-pointer is don?t ca re during this operation, but for fu ture compatibility it is recommended to load the z-pointer with 0x0001 (same as used fo r reading the lock bits). for future compatibility it is also recommended to set bits 7, 6, 1, and 0 in r0 to ?1? when writing the lock bits. when programming the lock bits the entire flash can be read during the operation. eeprom write prevents writing to spmcr note that an eeprom write oper ation will block all software progra mming to flash. reading the fuses and lock bits from software will also be prevented during the eeprom write operation. it is recommended that the user checks the status bit (eewe) in the eecr register and verifies that the bit is cleared before writing to the spmcr register. reading the fuse and lock bits from software it is possible to read both the fuse and lock bits from software. to read the lock bits, load the z-pointer with 0x0001 and set the blbset and spmen bits in spmcr. when an lpm instruc- tion is executed within three cpu cycles after the blbset and spmen bits are set in spmcr, the value of the lock bits will be loaded in the destination register. the blbset and spmen bits will auto-clear upon completion of reading the lo ck bits or if no lpm instruction is executed within three cpu cycles or no spm instruction is executed within four cpu cycles. when blb- set and spmen are cleared, lpm will work as described in the instruction set manual. bit 76543210 r0 1 1 blb12 blb11 blb02 blb01 1 1 bit 76543210 rd ? ? blb12 blb11 blb02 blb01 lb2 lb1 226 2513k?avr?07/09 atmega162/v the algorithm for reading the fuse low byte is similar to the one described above for reading the lock bits. to read the fuse low byte, load the z-pointer with 0x0000 and set the blbset and spmen bits in spmcr. when an lpm instructio n is executed within three cycles after the blbset and spmen bits are set in the spmcr, the va lue of the fuse low byte (flb) will be loaded in the destination register as shown below. refer to table 100 on page 233 for a detailed description and mapping of the fuse low byte. similarly, when reading the fuse high byte, load 0x0003 in the z-pointer. when an lpm instruc- tion is executed within three cycles after the blbset and spme n bits are set in the spmcr, the value of the fuse high byte (fhb) will be load ed in the destination re gister as shown below. refer to table 98 on page 232 for detailed description and mapping of the fuse high byte. when reading the extended fuse byte, load 0x0002 in the z-pointer. when an lpm instruction is executed within three cycles after the blbset and spmen bits are set in the spmcr, the value of the extended fuse byte (efb) will be loaded in the desti nation register as shown below. refer to table 98 on page 232 for detailed description and mapping of the extended fuse byte. fuse and lock bits that are programmed, will be read as zero. fuse and lock bits that are unprogrammed, will be read as one. preventing flash corruption during periods of low v cc , the flash program can be corrupted because the supply voltage is too low for the cpu and the flash to operate properly. these issues are the same as for board level systems using the flash, and the same design solutions should be applied. a flash program corruption can be caused by two situ ations when the voltage is too low. first, a regular write sequence to the flash requires a minimum voltage to operate correctly. secondly, the cpu itself can execute instruct ions incorrectly, if the supply voltage for executing instructions is too low. flash corruption can easily be avoided by following these design recommendations (one is sufficient): 1. if there is no need for a boot loader update in the system, program the boot loader lock bits to prevent any boot loader software updates. 2. keep the avr reset active (low) during peri ods of insufficient power supply voltage. this can be done by enabling the internal brown-out detector (bod) if the operating volt- age matches the detection level. if not, an external low v cc reset protection circuit can be used. if a reset occurs while a write operat ion is in progress, the write operation will be completed provided that the power supply voltage is sufficient. 3. keep the avr core in power-down sleep mode during periods of low v cc . this will pre- vent the cpu from attempting to decode and execute instructions, effectively protecting the spmcr register and thus the flash from unintentional writes. bit 76543210 rd flb7 flb6 flb5 flb4 flb3 flb2 flb1 flb0 bit 76543210 rd fhb7 fhb6 fhb5 fhb4 fhb3 fhb2 fhb1 fhb0 bit 76543210 rd ? ? ? efb4 efb3 efb2 efb1 ? 227 2513k?avr?07/09 atmega162/v programming time for flash when using spm the calibrated rc oscillator is used to time flash accesses. table 92 shows the typical pro- gramming time for flash accesses from the cpu. simple assembly code example for a boot loader ;-the routine writes one?page of data from ram to flash ; the first data locatio? in ram is pointed to by the y pointer ; the first data locatio? in flash is pointed to by the z-pointer ;-error handling is not ?ncluded ;-the routine must be pl?ced inside the boot space ; (at least the do_spm s?b routine). only code inside nrww section can ; be read during self-pr?gramming (page erase and page write). ;-registers used: r0, r1? temp1 (r16), temp2 (r17), looplo (r24), ; loophi (r25), spmcrval?(r20) ; storing and restoring ?f registers is not included in the routine ; register usage can be ?ptimized at the expense of code size ;-it is assumed that eit?er the interrupt table is moved to the boot ; loader section or that?the interrupts are disabled. .equ pagesizeb = pagesize*2 ;pagesizeb is page size in bytes, not ; words .org smallbootstart write_page: ; page erase ldi spmcrval, (1< 230 2513k?avr?07/09 atmega162/v note: 1. z15:z14: always ignored z0: should be zero for all spm commands, byte select for the lpm instruction. see ?addressing the flash during self-programming? on page 223 for details about the use of z-pointer during self-programming. table 95. explanation of different variables used in figure 95 and the mapping to the z- pointer (1) variable corresponding z-value description pcmsb 12 most significant bit in the program counter. (the program counter is 13 bits pc[12:0]) pag e m s b 5 most significant bit which is used to address the words within one page (64 words in a page requires 6 bits pc [5:0]). zpcmsb z13 bit in z-register that is mapped to pcmsb. because z0 is not used, the zpcmsb equals pcmsb + 1. zpagemsb z6 bit in z-register that is mapped to pcmsb. because z0 is not used, the zpagemsb equals pagemsb + 1. pcpage pc[12:6] z13:z7 program counter page address: page select, for page erase and page write pcword pc[5:0] z6:z1 program counter word address: word select, for filling temporary buffer (must be zero during page write operation) 231 2513k?avr?07/09 atmega162/v memory programming program and data memory lock bits the atmega162 provides six lock bits which can be left unprogrammed (?1?) or can be pro- grammed (?0?) to obtain the additional features listed in table 97 . the lock bits can only be erased to ?1? with the chip erase command. note: 1. ?1? means unprogrammed, ?0? means programmed table 96. lock bit byte (1) lock bit byte bit no description default value 7 ? 1 (unprogrammed) 6 ? 1 (unprogrammed) blb12 5 boot lock bit 1 (unprogrammed) blb11 4 boot lock bit 1 (unprogrammed) blb02 3 boot lock bit 1 (unprogrammed) blb01 2 boot lock bit 1 (unprogrammed) lb2 1 lock bit 1 (unprogrammed) lb1 0 lock bit 1 (unprogrammed) table 97. lock bit protection modes (1)(2) memory lock bits protection type lb mode lb2 lb1 1 1 1 no memory lock features enabled. 210 further programming of the flash and eeprom is disabled in parallel and spi/jtag serial programming mode. the fuse bits are locked in both serial and parallel programming mode (1) . 300 further programming and verification of the flash and eeprom is disabled in parallel and spi/jtag serial programming mode. also the b oot lock bits and the fuse bits are locked in both serial and parallel programming mode (1) . blb0 mode blb02 blb01 111 no restrictions for spm or lpm accessing the application section. 2 1 0 spm is not allowed to write to the application section. 300 spm is not allowed to write to the application section, and lpm executing from the boot loader section is not allowed to read from the application section. if interrupt vectors are placed in the boot loader section, interrupts are disabled while executing from the application section. 401 lpm executing from the boot loader section is not allowed to read from the application section. if interrupt vectors are placed in the boot loader section, interrupts are disabled while executing from the application section. 232 2513k?avr?07/09 atmega162/v notes: 1. program the fuse bits and boot lock bits before programming the lb1 and lb2. 2. ?1? means unprogrammed, ?0? means programmed fuse bits the atmega162 has three fuse bytes. table 99 and table 100 describe briefly the functionality of all the fuses and how they are mapped into the fuse bytes. note that the fuses are read as logical zero, ?0?, if they are programmed. notes: 1. see ?atmega161 compatibility mode? on page 4 for details. 2. see table 19 on page 50 for bodlevel fuse decoding. blb1 mode blb12 blb11 111 no restrictions for spm or lpm accessing the boot loader section. 2 1 0 spm is not allowed to write to the boot loader section. 300 spm is not allowed to write to the boot loader section, and lpm executing from the application section is not allowed to read from the boot loader section. if interrupt vectors are placed in the application section, interrupts are disabled while executing from the boot loader section. 401 lpm executing from the application section is not allowed to read from the boot loader se ction. if interrupt vectors are placed in the application section, interrupts are disabled while executing from the boot loader section. table 97. lock bit protection modes (1)(2) (continued) memory lock bits protection type table 98. extended fuse byte (1)(2) fuse low byte bit no description default value ?7? 1 ?6? 1 ?5? 1 m161c 4 atmega161 compatibility mode 1 (unprogrammed) bodlevel2 (2) 3 brown-out detector trigger level 1 (unprogrammed) bodlevel1 (2) 2 brown-out detector trigger level 1 (unprogrammed) bodlevel0 (2) 1 brown-out detector trigger level 1 (unprogrammed) ?0? 1 233 2513k?avr?07/09 atmega162/v notes: 1. the spien fuse is not accessible in spi serial programming mode. 2. the default value of bootsz1:0 results in maximum boot size. see table 93 on page 228 for details. 3. never ship a product with the ocden fuse prog rammed regardless of the setting of lock bits and the jtagen fuse. a programmed ocden fu se enables some parts of the clock system to be running in all sleep modes. this may increase the power consumption. 4. if the jtag interface is left unconnected, the jt agen fuse should if possible be disabled. this to avoid static current at the tdo pin in the jtag interface. notes: 1. the default value of sut1:0 results in maxi mum start-up time for the default clock source. see table 12 on page 39 for details. 2. the default setting of c ksel3:0 results in internal rc oscillator @ 8 mhz. see table 5 on page 36 for details. 3. the ckout fuse allow the system cl ock to be output on portb 0. see ?clock output buffer? on page 40 for details. 4. see ?system clock prescaler? on page 41 for details. the status of the fuse bits is not affected by chip erase. note that the fuse bits are locked if lock bit1 (lb1) is programmed. program the fuse bits before programming the lock bits. table 99. fuse high byte fuse low byte bit no description default value ocden (3) 7 enable ocd 1 (unprogrammed, ocd disabled) jtagen (4) 6 enable jtag 0 (programmed, jtag enabled) spien (1) 5 enable serial program and data downloading 0 (programmed, spi prog. enabled) wdton 4 watchdog timer always on 1 (unprogrammed) eesave 3 eeprom memory is preserved through the chip erase 1 (unprogrammed, eeprom not preserved) bootsz1 2 select boot size (see table 93 for details) 0 (programmed) (2) bootsz0 1 select boot size (see table 93 for details) 0 (programmed) (2) bootrst 0 select reset vector 1 (unprogrammed) table 100. fuse low byte fuse low byte bit no description default value ckdiv8 (4) 7 divide clock by 8 0 (programmed) ckout (3) 6 clock output 1 (unprogrammed) sut1 5 select start-up time 1 (unprogrammed) (1) sut0 4 select start-up time 0 (programmed) (1) cksel3 3 select clock source 0 (programmed) (2) cksel2 2 select clock source 0 (programmed) (2) cksel1 1 select clock source 1 (unprogrammed) (2) cksel0 0 select clock source 0 (programmed) (2) 234 2513k?avr?07/09 atmega162/v latching of fuses the fuse values are latched when the device enters programming mode and changes of the fuse values will have no effect until the part leaves programmi ng mode. this does not apply to the eesave fuse which will take effect once it is programmed. the fuses are also latched on power-up in normal mode. signature bytes all atmel microcontrollers have a 3-byte signat ure code which identifies the device. this code can be read in both serial and parallel mode, al so when the device is locked. the three bytes reside in a separate address space. for the atmega162 the signature bytes are: 1. 0x000: 0x1e (indicates manufactured by atmel). 2. 0x001: 0x94 (indicates 16kb flash memory). 3. 0x002: 0x04 (indicates atmega162 device when 0x001 is 0x94). calibration byte the atmega162 has a one-byte calibration va lue for the internal rc oscillator. this byte resides in the high byte of address 0x000 in the signature address space. during reset, this byte is automatically written into the osccal register to ensure correct frequency of the cali- brated rc oscillator. parallel programming parameters, pin mapping, and commands this section describes how to parallel program and verify flash program memory, eeprom data memory, memory lock bits, and fuse bits in the atmega162. pulses are assumed to be at least 250 ns unless otherwise noted. signal names in this section, some pins of the atmega162 are referenced by signal names describing their functionality during parallel programming, see figure 96 and table 101 . pins not described in the following table are referenced by pin names. the xa1/xa0 pins determine the action executed when the xtal1 pin is given a positive pulse. the bit coding is shown in table 103 . when pulsing wr or oe , the command loaded determines the action executed. the different commands are shown in table 104 . figure 96. parallel programming vcc +5v gnd xtal1 pd1 pd2 pd3 pd4 pd5 pd6 pb7 - pb0 data reset pd7 +12 v bs1 xa0 xa1 oe rdy/bsy pagel pa0 wr bs2 235 2513k?avr?07/09 atmega162/v table 101. pin name mapping signal name in programming mode pin name i/o function rdy/bsy pd1 o 0: device is busy programming, 1: device is ready for new command oe pd2 i output enable (active low) wr pd3 i write pulse (active low) bs1 pd4 i byte select 1 (?0? selects low byte, ?1? selects high byte) xa0 pd5 i xtal action bit 0 xa1 pd6 i xtal action bit 1 pagel pd7 i program memory and eeprom data page load bs2 pa0 i byte select 2 (?0? selects low byte, ?1? selects 2?nd high byte) data pb7 - 0 i/o bi-directional data bus (output when oe is low) table 102. pin values used to enter programming mode pin symbol value pagel prog_enable[3] 0 xa1 prog_enable[2] 0 xa0 prog_enable[1] 0 bs1 prog_enable[0] 0 table 103. xa1 and xa0 coding xa1 xa0 action when xtal1 is pulsed 0 0 load flash or eeprom address (high or low address byte determined by bs1) 0 1 load data (high or low data byte for flash determined by bs1). 1 0 load command 1 1 no action, idle 236 2513k?avr?07/09 atmega162/v parallel programming enter programming mode the following algorithm puts the devi ce in parallel programming mode: 1. apply 4.5 - 5.5v between v cc and gnd, and wait at least 100 s. 2. set reset to ?0? and toggle xtal1 at least six times. 3. set the prog_enable pins listed in table 102 on page 235 to ?0000? and wait at least 100 ns. 4. apply 11.5 - 12.5v to reset . any activity on prog_enable pins within 100 ns after +12v has been applied to reset , will cause the device to fail entering programming mode. considerations for efficient programming the loaded command and address are retained in the device during programming. for efficient programming, the following should be considered. ? the command needs only be loaded once when writing or reading multiple memory locations. ? skip writing the data value 0xff, that is t he contents of the enti re eeprom (unless the eesave fuse is programmed) and flash after a chip erase. ? address high byte needs only be loaded before programming or reading a new 256-word window in flash or 256 byte eeprom. this consideration also applies to signature bytes reading. table 104. command byte bit coding command byte command executed 1000 0000 chip erase 0100 0000 write fuse bits 0010 0000 write lock bits 0001 0000 write flash 0001 0001 write eeprom 0000 1000 read signature bytes and calibration byte 0000 0100 read fuse and lock bits 0000 0010 read flash 0000 0011 read eeprom table 105. no. of words in a page and no. of pages in the flash flash size page size pcword no. of pages pcpage pcmsb 8k words (16k bytes) 64 words pc[5:0] 128 pc[12:6] 12 table 106. no. of words in a page and no. of pages in the eeprom eeprom size page size pcword no. of pages pcpage eeamsb 512 bytes 4 bytes eea[1:0] 128 eea[8:2] 8 237 2513k?avr?07/09 atmega162/v chip erase the chip erase will erase the flash and eeprom (1) memories plus lock bits. the lock bits are not reset until the program memory has been completely erased. the fuse bits are not changed. a chip eras e must be performed before the flash or eeprom are reprogrammed. note: 1. the eeprpom memory is preserved duri ng chip erase if the eesave fuse is programmed. load command ?chip erase? 1. set xa1, xa0 to ?10?. this enables command loading. 2. set bs1 to ?0?. 3. set data to ?1000 0000?. this is the command for chip erase. 4. give xtal1 a positive pulse. this loads the command. 5. give wr a negative pulse. this starts the chip erase. rdy/bsy goes low. 6. wait until rdy/bsy goes high before loading a new command. programming the flash the flash is organized in pages, see table 105 on page 236 . when programming the flash, the program data is latched into a page buffer. this allows one page of program data to be pro- grammed simultaneously. the following procedure describes how to program the entire flash memory: a. load command ?write flash? 1. set xa1, xa0 to ?10?. this enables command loading. 2. set bs1 to ?0?. 3. set data to ?0001 0000?. this is the command for write flash. 4. give xtal1 a positive pulse. this loads the command. b. load address low byte 1. set xa1, xa0 to ?00?. this enables address loading. 2. set bs1 to ?0?. this selects low address. 3. set data = address low byte (0x00 - 0xff). 4. give xtal1 a positive pulse. this loads the address low byte. c. load data low byte 1. set xa1, xa0 to ?01?. this enables data loading. 2. set data = data low byte (0x00 - 0xff). 3. give xtal1 a positive pulse. this loads the data byte. d. load data high byte 1. set bs1 to ?1?. this selects high data byte. 2. set xa1, xa0 to ?01?. this enables data loading. 3. set data = data high byte (0x00 - 0xff). 4. give xtal1 a positive pulse. this loads the data byte. e. latch data 1. set bs1 to ?1?. this selects high data byte. 2. give pagel a positive pulse. this latches the data bytes (see figure 98 for signal waveforms). f. repeat b through e until the entire buffer is filled or until all data within the page is loaded. 238 2513k?avr?07/09 atmega162/v while the lower bits in the address are mapped to words within the page, the higher bits address the pages within the flash. this is illustrated in figure 97 on page 238 . note that if less than eight bits are required to address words in the page (pagesize < 256), the most significant bit(s) in the address low byte are used to address the page when performing a page write. g. load address high byte 1. set xa1, xa0 to ?00?. this enables address loading. 2. set bs1 to ?1?. this selects high address. 3. set data = address high byte (0x00 - 0xff). 4. give xtal1 a positive pulse. this loads the address high byte. h. program page 1. give wr a negative pulse. this starts programming of the entire page of data. rdy/bsy goes low. 2. wait until rdy/bsy goes high. (see figure 98 for signal waveforms) i. repeat b through h until the entire flash is programmed or until all data has been programmed. j. end page programming 1. 1. set xa1, xa0 to ?10?. this enables command loading. 2. set data to ?0000 0000?. this is the command for no operation. 3. give xtal1 a positive pulse. this loads the command, and the internal write signals are reset. figure 97. addressing the flash which is organized in pages (1) note: 1. pcpage and pcword are listed in table 105 on page 236 . program memory word address within a page page address within the flash instruction word page pcword[pagemsb:0]: 00 01 02 pageend page pcword pcpage pcmsb pagemsb program counter 239 2513k?avr?07/09 atmega162/v figure 98. programming the flash waveforms note: ?xx? is don?t care. the letters refer to the programming description above. programming the eeprom the eeprom is organized in pages, see table 106 on page 236 . when programming the eeprom, the program data is latche d into a page buffer. this al lows one page of data to be programmed simultaneously. th e programming algorithm for th e eeprom data memory is as follows (refer to ?programming the flash? on page 237 for details on command, address and data loading): 1. a: load command ?0001 0001?. 2. g: load address high byte (0x00 - 0xff). 3. b: load address low byte (0x00 - 0xff). 4. c: load data (0x00 - 0xff). 5. e: latch data (give pagel a positive pulse). k: repeat 3 through 5 until the entire buffer is filled. l: program eeprom page 1. set bs to ?0?. 2. give wr a negative pulse. this starts pr ogramming of the eeprom page. rdy/bsy goes low. 3. wait until to rdy/bsy goes high before programming the next page (see figure 99 for signal waveforms). rdy/bsy wr oe reset +12v pagel bs2 0x10 addr. low addr. high data data low data high addr. low data low data high xa1 xa0 bs1 xtal1 xx xx xx abcdebcdegh f 240 2513k?avr?07/09 atmega162/v figure 99. programming the eeprom waveforms reading the flash the algorithm for reading the flash memory is as follows (refer to ?programming the flash? on page 237 for details on command and address loading): 1. a: load command ?0000 0010?. 2. g: load address high byte (0x00 - 0xff). 3. b: load address low byte (0x00 - 0xff). 4. set oe to ?0?, and bs1 to ?0?. the flash word low byte can now be read at data. 5. set bs to ?1?. the flash word high byte can now be read at data. 6. set oe to ?1?. reading the eeprom the algorithm for reading the eeprom memory is as follows (refer to ?programming the flash? on page 237 for details on command and address loading): 1. a: load command ?0000 0011?. 2. g: load address high byte (0x00 - 0xff). 3. b: load address low byte (0x00 - 0xff). 4. set oe to ?0?, and bs1 to ?0?. the eeprom data byte can now be read at data. 5. set oe to ?1?. programming the fuse low bits the algorithm for programming the fuse low bits is as follows (refer to ?programming the flash? on page 237 for details on command and data loading): 1. a: load command ?0100 0000?. 2. c: load data low byte. bit n = ?0? programs and bit n = ?1? erases the fuse bit. 3. set bs1 to ?0? and bs2 to ?0?. this selects low data byte. 4. give wr a negative pulse and wait for rdy/bsy to go high. rdy/bsy wr oe reset +12v pagel bs2 0x11 addr. high data addr. low data addr. low data xx xa1 xa0 bs1 xtal1 xx agbceb c el k 241 2513k?avr?07/09 atmega162/v programming the fuse high bits the algorithm for programming the fuse high bits is as follows (refer to ?programming the flash? on page 237 for details on command and data loading): 1. a: load command ?0100 0000?. 2. c: load data low byte. bit n = ?0? programs and bit n = ?1? erases the fuse bit. 3. set bs1 to ?1? and bs2 to ?0?. this selects high data byte. 4. give wr a negative pulse and wait for rdy/bsy to go high. 5. set bs1 to ?0?. this selects low data byte. programming the extended fuse bits the algorithm for programming the extended fuse bits is as follows (refer to ?programming the flash? on page 237 for details on command and data loading): 1. 1. a: load command ?0100 0000?. 2. 2. c: load data low byte. bit n = ?0? programs and bit n = ?1? erases the fuse bit. 3. 3. set bs1 to ?0? and bs2 to ?1?. this selects extended data byte. 4. 4. give wr a negative pulse and wait for rdy/bsy to go high. 5. 5. set bs2 to ?0?. this selects low data byte. figure 100. programming the fuses waveforms rdy/bsy wr oe reset +12v pagel 0x40 data data xx xa1 xa0 bs1 xtal1 ac 0x40 data xx ac write fuse low byte write fuse high byte 0x40 data xx ac write extended fuse byte bs2 242 2513k?avr?07/09 atmega162/v programming the lock bits the algorithm for programming the lock bits is as follows (refer to ?programming the flash? on page 237 for details on command and data loading): 1. a: load command ?0010 0000?. 2. c: load data low byte. bit n = ?0? programs the lock bit. if lb mode 3 is programmed (lb1 and lb2 is programmed), it is not possible to program the boot lock bits by any external programming mode. 3. give wr a negative pulse and wait for rdy/bsy to go high. the lock bits can only be cleared by executing chip erase. reading the fuse and lock bits the algorithm for reading the fuse and lock bits is as follows (refer to ?programming the flash? on page 237 for details on command loading): 1. a: load command ?0000 0100?. 2. set oe to ?0?, bs2 to ?0? and bs1 to ?0?. the status of the fuse low bits can now be read at data (?0? means programmed). 3. set oe to ?0?, bs2 to ?1? and bs1 to ?1?. the status of the fuse high bits can now be read at data (?0? means programmed). 4. set oe to ?0?, bs2 to ?1? and bs1 to ?0?. the status of the extended fuse bits can now be read at data (?0? means programmed). 5. set oe to ?0?, bs2 to ?0? and bs1 to ?1?. the status of the lock bits can now be read at data (?0? means programmed). 6. set oe to ?1?. figure 101. mapping between bs1, bs2 and the fuse and lock bits during read reading the signature bytes the algorithm for reading the signature bytes is as follows (refer to ?programming the flash? on page 237 for details on command and address loading): 1. a: load command ?0000 1000?. 2. b: load address low byte (0x00 - 0x02). 3. set oe to ?0?, and bs to ?0?. the selected signature byte can now be read at data. 4. set oe to ?1?. lock bits 0 1 bs2 fuse high byte 0 1 bs1 data fuse low byte 0 1 bs2 extended fuse byte 243 2513k?avr?07/09 atmega162/v reading the calibration byte the algorithm for reading the calibration byte is as follows (refer to ?programming the flash? on page 237 for details on command and address loading): 1. a: load command ?0000 1000?. 2. b: load address low byte, 0x00. 3. set oe to ?0?, and bs1 to ?1?. the calibration byte can now be read at data. 4. set oe to ?1?. parallel programming characteristics figure 102. parallel programming timing, including some general timing requirements figure 103. parallel programming timing, loading sequence with timing requirements (1) note: 1. the timing requirements shown in figure 102 (i.e., t dvxh , t xhxl , and t xldx ) also apply to load- ing operation. data & contol (data, xa0/1, bs1, bs2) xtal1 t xhxl t wlwh t dvxh t xldx t plwl t wlrh wr rdy/bsy pagel t phpl t plbx t bvph t xlwl t wlbx t bvwl wlrl xtal1 pagel t plxh xlxh t t xlph addr0 (low byte) data (low byte) data (high byte) addr1 (low byte) data bs1 xa0 xa1 load address (low byte) load data (low byte) load data (high byte) load data load address (low byte) 244 2513k?avr?07/09 atmega162/v figure 104. parallel programming timing, reading sequence (within the same page) with timing requirements (1) note: 1. the timing requirements shown in figure 102 (i.e., t dvxh , t xhxl , and t xldx ) also apply to read- ing operation. table 107. parallel programming characteristics, v cc = 5 v 10% symbol parameter min typ max units v pp programming enable voltage 11.5 12.5 v i pp programming enable current 250 a t dvxh data and control valid before xtal1 high 67 ns t xlxh xtal1 low to xtal1 high 200 ns t xhxl xtal1 pulse width high 150 ns t xldx data and control hold after xtal1 low 67 ns t xlwl xtal1 low to wr low 0 ns t xlph xtal1 low to pagel high 0 ns t plxh pagel low to xtal1 high 150 ns t bvph bs1 valid before pagel high 67 ns t phpl pagel pulse width high 150 ns t plbx bs1 hold after pagel low 67 ns t wlbx bs2/1 hold after wr low 67 ns t plwl pagel low to wr low 67 ns t bvwl bs1 valid to wr low 67 ns t wlwh wr pulse width low 150 ns t wlrl wr low to rdy/bsy low 0 1 s t wlrh wr low to rdy/bsy high (1) 3.7 4.5 ms t wlrh_ce wr low to rdy/bsy high for chip erase (2) 7.5 9 ms t xlol xtal1 low to oe low 0 ns xtal1 oe addr0 (low byte) data (low byte) data (high byte) addr1 (low byte) data bs1 xa0 xa1 load address (low byte) read data (low byte) read data (high byte) load address (low byte) t bvdv t oldv t xlol t ohdz 245 2513k?avr?07/09 atmega162/v notes: 1. t wlrh is valid for the write flash, write eeprom , write fuse bits and write lock bits commands. 2. t wlrh_ce is valid for the chip erase command. serial downloading spi serial programming pin mapping both the flash and eeprom memo ry arrays can be programmed using the serial spi bus while reset is pulled to gnd. the serial interface consists of pins sck, mosi (input) and miso (out- put). after reset is set low, the programming enable instruction needs to be executed first before program/erase operations can be executed. note, in table 108 on page 245 , the pin mapping for spi programming is listed. not all pa rts use the spi pins dedicated for the internal spi interface. figure 105. spi serial programming and verify (1) note: 1. if the device is clocked by the internal oscillator, it is no need to connect a clock source to the xtal1 pin. when programming the eeprom, an auto-erase cycle is built into the self-timed programming operation (in the serial mode only) and there is no need to first execute the chip erase instruction. the chip erase operation turns the content of every memory location in both the program and eeprom arrays into 0xff. t bvdv bs1 valid to data valid 0 250 ns t oldv oe low to data valid 250 ns t ohdz oe high to data tri-stated 250 ns table 107. parallel programming characteristics, v cc = 5 v 10% (continued) symbol parameter min typ max units table 108. pin mapping spi serial programming symbol pins i/o description mosi pb5 i serial data in miso pb6 o serial data out sck pb7 i serial clock vcc gnd xtal1 sck miso mosi reset 246 2513k?avr?07/09 atmega162/v depending on cksel fuses, a valid clock must be present. the minimum low and high periods for the serial clock (sck) input are defined as follows: low:> 2 cpu clock cycles for f ck < 12 mhz, 3 cpu clock cycles for f ck >= 12 mhz high:> 2 cpu clock cycles for f ck < 12 mhz, 3 cpu clock cycles for f ck >= 12 mhz spi serial programming algorithm when writing serial data to the atmega162, data is clocked on the rising edge of sck. when reading data from the at mega162, data is clocked on the falling edge of sck. see figure 106 . to program and verify the atmega162 in the spi serial programming mode, the following sequence is recommended (see four byte instruction formats in table 110 ): 1. power-up sequence: apply power between v cc and gnd while reset and sck are set to ?0?. in some sys- tems, the programmer can not guarantee that sck is held low during power-up. in this case, reset must be given a positive pulse of at least two cpu clock cycles duration after sck has been set to ?0?. 2. wait for at least 20 ms and enable spi serial programming by sending the programming enable serial instruction to pin mosi. 3. the spi serial programming instructions will no t work if the communication is out of syn- chronization. when in sync. the second byte (0x53), will echo back when issuing the third byte of the programming enable instruction. whether the echo is correct or not, all four bytes of the instruction must be transmitted. if the 0x53 did not echo back, give reset a positive pulse and issue a new programming enable command. 4. the flash is programmed one page at a time. the page size is found in table 105 on page 236 . the memory page is loaded one byte at a time by supplying the 6 lsb of the address and data together with the load program memory page instruction. to ensure correct loading of the page, the data low byte must be loaded before data high byte is applied for a given address. the program memory page is stored by loading the write program memory page instruct ion with the 8 msb of the addr ess. if polling is not used, the user must wait at least t wd_flash before issuing the next page. (see table 109 .) accessing the spi serial programming interface before the flash write operation com- pletes can result in incorrect programming. 5. the eeprom array can either be programmed one page at a time or it can be pro- grammed byte by byte. for page programming, the following algorithm is used: the eeprom memory page is loaded one byte at a time by supplying the 2 lsb of the address and da ta together with th e load eeprom memory page instruction. the eeprom memory page is stored by loading the write eeprom memory page instruction with the 8 msb of the address. if po lling is not used, the user must wait at least t wd_eeprom before issu- ing the next page. (see table 99 .) accessing the spi serial programming interface before the eeprom write oper ation completes ca n result in inco rrect programming. alternatively, the eeprom can be programmed bytewise: the eeprom array is programmed one byte at a time by supplying the address and data together with the write eeprom instruction. an eeprom memory location is first automat- ically erased before new data is written. if polling is not used, the user must wait at least t wd_eeprom before issuing the next byte. (see table 109 .) in a chip erased device, no 0xffs in the data file(s) need to be programmed. 6. any memory location can be verified by using the read instruction which returns the con- tent at the selected address at serial output miso. 247 2513k?avr?07/09 atmega162/v 7. at the end of the programming session, reset can be set high to commence normal operation. 8. power-off sequence (if needed): set reset to ?1?. tu r n v cc power off. figure 106. spi serial progra mming waveforms table 109. minimum wait delay befo re writing the next flash or eeprom location symbol minimum wait delay t wd_flash 4.5 ms t wd_eeprom 9.0 ms t wd_erase 9.0 ms t wd_fuse 4.5 ms msb msb lsb lsb serial clock input (sck) serial data input (mosi) (miso) sample serial data output 248 2513k?avr?07/09 atmega162/v table 110. spi serial programming instruction set (1) instruction instruction format operation byte 1 byte 2 byte 3 byte4 programming enable 1010 1100 0101 0011 xxxx xxxx xxxx xxxx enable spi serial programming after reset goes low. chip erase 1010 1100 100x xxxx xxxx xxxx xxxx xxxx chip erase eeprom and flash. read program memory 0010 h 000 00 aa aaaa bbbb bbbb oooo oooo read h (high or low) data o from program memory at word address a : b . load program memory page 0100 h 000 00xx xxxx xx bb bbbb iiii iiii write h (high or low) data i to program memory page at word address b . data low byte must be loaded before data high byte is applied within the same address. write program memory page 0100 1100 00 aa aaaa bb xx xxxx xxxx xxxx write program memory page at address a : b . read eeprom memory 1010 0000 00xx xx aa bbbb bbbb oooo oooo read data o from eeprom memory at address a : b . write eeprom memory (byte access) 1100 0000 00xx xx aa bbbb bbbb iiii iiii write data i to eeprom memory at address a : b . load eeprom memory page (page access) 1100 0001 0000 0000 0000 00 bb iiii iiii load data i to eeprom memory page buffer. after data is loaded, program eeprom page. write eeprom memory page (page access) 1100 0010 00xx xx aa bbbb bb 00 xxxx xxxx write eeprom page at address a : b . read lock bits 0101 1000 0000 0000 xxxx xxxx xx oo oooo read lock bits. ?0? = programmed, ?1? = unprogrammed. see table 96 on page 231 for details. write lock bits 1010 1100 111x xxxx xxxx xxxx 11 ii iiii write lock bits. set bits = ?0? to program lock bits. see table 96 on page 231 for details. read signature byte 0011 0000 00xx xxxx xxxx xx bb oooo oooo read signature byte o at address b . write fuse bits 1010 1100 1010 0000 xxxx xxxx iiii iiii set bits = ?0? to program, ?1? to unprogram. see table 100 on page 233 for details. write fuse high bits 1010 1100 1010 1000 xxxx xxxx iiii iiii set bits = ?0? to program, ?1? to unprogram. see table 99 on page 233 for details. write extended fuse bits 1010 1100 1010 0100 xxxx xxxx xxxx xxii set bits = ?0? to program, ?1? to unprogram. see table 98 on page 232 for details. read fuse bits 0101 0000 0000 0000 xxxx xxxx oooo oooo read fuse bits. ?0? = programmed, ?1? = unprogrammed. see table 100 on page 233 for details. 249 2513k?avr?07/09 atmega162/v note: 1. a = address high bits, b = address low bits, h = 0 ? low byte, 1 ? high byte, o = data out, i = data in, x = don?t care spi serial programming characteristics for characteristics of the spi module, see ?spi timing characteristics? on page 268 . read fuse high bits 0101 1000 0000 1000 xxxx xxxx oooo oooo read fuse high bits. ?0? = pro- grammed, ?1? = unprogrammed. see table 99 on page 233 for details. read extended fuse bits 0101 0000 0000 1000 xxxx xxxx oooo oooo read extended fuse bits. ?0? = pro-grammed, ?1? = unprogrammed. see table 98 on page 232 for details. read calibration byte 0011 1000 00xx xxxx 0000 0000 oooo oooo read calibration byte poll rdy/bsy 1111 0000 0000 0000 xxxx xxxx xxxx xxx o if o = ?1?, a programming operation is still busy. wait until this bit returns to ?0? before applying another command. table 110. spi serial programming instruction set (1) (continued) instruction instruction format operation byte 1 byte 2 byte 3 byte4 250 2513k?avr?07/09 atmega162/v programming via the jtag interface programming through the jtag interface requires control of the four jtag specific pins: tck, tms, tdi, and tdo. control of the reset and clock pins is not required. to be able to use the jtag interface, the jtagen fuse must be programmed. the device is default shipped with the fuse programmed. in addition, the jtd bit in mcucsr must be cleared. alternatively, if the jtd bit is set, the external reset can be forced low. then, the jtd bit will be cleared after two chip clocks, and th e jtag pins are avail able for programming. this provides a means of usin g the jtag pins as normal port pins in running mode while still allowing in-system programming via the jtag interface. no te that this technique can not be used when using the jtag pins for boundary-scan or on-chi p debug. in these cases the jtag pins must be dedicated for this purpose. as a definition in this datasheet, the lsb is shifted in and out first of all shift registers. programming specific jtag instructions the instruction register is 4-bit wide, supporting up to 16 instructions. the jtag instructions useful for programming are listed below. the opcode for each instruction is shown behind the instruction name in hex format. the text describes which data register is selected as path between tdi and tdo for each instruction. the run-test/idle state of the tap controller is used to generate internal clocks. it can also be used as an idle state between jtag sequences. the state machine sequence for changing the instruction word is shown in figure 107 . 251 2513k?avr?07/09 atmega162/v figure 107. state machine sequence for changing the instruction word test-logic-reset run-test/idle shift-dr exit1-dr pause-dr exit2-dr update-dr select-ir scan capture-ir shift-ir exit1-ir pause-ir exit2-ir update-ir select-dr scan capture-dr 0 1 0 11 1 00 00 11 1 0 1 1 0 1 0 0 1 0 1 1 0 1 0 0 0 0 1 1 252 2513k?avr?07/09 atmega162/v avr_reset (0xc) the avr specific public jtag in struction for setting the avr device in the reset mode or taking the device out from the reset mode. the tap controller is not reset by this instruction. the one bit reset register is selected as data register. note that the reset will be active as long as there is a logic ?one? in the reset chain. the output from this chain is not latched. the active states are: ? shift-dr: the reset register is shifted by the tck input. prog_enable (0x4) the avr specific public jtag instruction for enabling programming via the jtag port. the 16- bit programming enable register is selected as data register. the active states are the following: ? shift-dr: the programming enable signature is shifted into the data register. ? update-dr: the programming enable signature is compared to the correct value, and programming mode is entered if the signature is valid. prog_commands (0x5) the avr specific public jtag instruction for entering programming commands via the jtag port. the 15-bit programming command register is selected as data register. the active states are the following: ? capture-dr: the result of the previous command is loaded into the data register. ? shift-dr: the data register is shifted by the tck input, shifting out the result of the previous command and shifting in the new command. ? update-dr: the programming command is applied to the flash inputs. ? run-test/idle: one clock cycle is generated, executing the applied command (not always required, see table 111 below). prog_pageload (0x6) the avr specific public jtag instruction to directly load the flash data page via the jtag port. the 1024 bit virtual flash page load register is se lected as register. this is a virtual scan chain with length equal to the number of bits in one fl ash page. internally the shift register is 8-bit. unlike most jtag instructions, the update-dr state is not used to transfer data from the shift register. the data are automatically transferred to the flash page buffer byte-by-byte in the shift-dr state by an internal state machine. this is the only active state: ? shift-dr: flash page data are shifted in fr om tdi by the tck input, and automatically loaded into the flash page one byte at a time. note: the jtag instruction prog_pageload can only be used if the avr device is the first device in jtag scan chain. if the avr cannot be the first de vice in the scan chain, the byte-wise program- ming algorithm must be used. prog_pageread (0x7) the avr specific public jtag instruction to read one full flash data page via the jtag port. the 1032 bit virtual flash page read register is selected as data register. this is a virtual scan chain with length equal to the number of bits in one flash page plus eight. internally the shift register is 8-bit. unlike most jtag instructions, the capture-dr state is not used to transfer data to the shift register. the data are automatically transferred from the flash page buffer byte-by-byte in the shift-dr state by an internal state machine. this is the only active state: ? shift-dr: flash data are automatically read one byte at a time and shifted out on tdo by the tck input. the tdi input is ignored. note: the jtag instruction prog_pageread can only be used if the avr device is the first device in jtag scan chain. if the avr cannot be the first de vice in the scan chain, the byte-wise program- ming algorithm must be used. 253 2513k?avr?07/09 atmega162/v data registers the data registers are selected by the jtag instruction registers described in section ?pro- gramming specific jtag instructions? on page 250 . the data registers relevant for programming operations are: ? reset register ? programming enable register. ? programming command register. ? virtual flash page load register. ? virtual flash page read register. reset register the reset register is a test data register used to reset the part during programming. it is required to reset the part before entering programming mode. a high value in the reset register corresponds to pulling the external reset low. the part is reset as long as there is a high value present in the reset register. depending on the fuse settings for the clock options, the part will remain reset for a reset time-out period (refer to ?clock sources? on page 36 ) after releasing the reset register. the output from this data register is not latched, so the reset will take place immediately, as shown in figure 86 on page 206 . programming enable register the programming enable register is a 16-bit regist er. the contents of this register is compared to the programming enable signature, binary code 1010_0011_0111_0000. when the contents of the register is equal to the programming enable signature, programming via the jtag port is enabled. the register is reset to 0 on power-on reset, and should always be reset when leaving programming mode. figure 108. programming enable register tdi tdo d a t a = dq clockdr & prog_enable programming enable 0xa370 254 2513k?avr?07/09 atmega162/v programming command register the programming command register is a 15-bit regist er. this register is us ed to serially shift in programming commands, and to serially shift out the result of the previous command, if any. the jtag programming instruction set is shown in table 111 . the state sequence when shifting in the programming commands is illustrated in figure 110 . figure 109. programming command register tdi tdo s t r o b e s a d d r e s s / d a t a flash eeprom fuses lock bits 255 2513k?avr?07/09 atmega162/v table 111. jtag programming instruction set instruction tdi sequen ce tdo sequence notes 1a. chip erase 0100011_10000000 0110001_10000000 0110011_10000000 0110011_10000000 xxxxxxx_xxxxxxxx xxxxxxx_xxxxxxxx xxxxxxx_xxxxxxxx xxxxxxx_xxxxxxxx 1b. poll for chip erase complete 0110011_10000000 xxxxx o x_xxxxxxxx (2) 2a. enter flash write 0100011_00010000 xxxxxxx_xxxxxxxx 2b. load address high byte 0000111_ aaaaaaaa xxxxxxx_xxxxxxxx (9) 2c. load address low byte 0000011_ bbbbbbbb xxxxxxx_xxxxxxxx 2d. load data low byte 0010011_ iiiiiiii xxxxxxx_xxxxxxxx 2e. load data high byte 0010111_ iiiiiiii xxxxxxx_xxxxxxxx 2f. latch data 0110111_00000000 1110111_00000000 0110111_00000000 xxxxxxx_xxxxxxxx xxxxxxx_xxxxxxxx xxxxxxx_xxxxxxxx (1) 2g. write flash page 0110111_00000000 0110101_00000000 0110111_00000000 0110111_00000000 xxxxxxx_xxxxxxxx xxxxxxx_xxxxxxxx xxxxxxx_xxxxxxxx xxxxxxx_xxxxxxxx (1) 2h. poll for page write complete 0110111_00000000 xxxxx o x_xxxxxxxx (2) 3a. enter flash read 0100011_00000010 xxxxxxx_xxxxxxxx 3b. load address high byte 0000111_ aaaaaaaa xxxxxxx_xxxxxxxx (9) 3c. load address low byte 0000011_ bbbbbbbb xxxxxxx_xxxxxxxx 3d. read data low and high byte 0110010_00000000 0110110_00000000 0110111_00000000 xxxxxxx_xxxxxxxx xxxxxxx_ oooooooo xxxxxxx_ oooooooo low byte high byte 4a. enter eeprom write 0100011_00010001 xxxxxxx_xxxxxxxx 4b. load address high byte 0000111_ aaaaaaaa xxxxxxx_xxxxxxxx (9) 4c. load address low byte 0000011_ bbbbbbbb xxxxxxx_xxxxxxxx 4d. load data byte 0010011_ iiiiiiii xxxxxxx_xxxxxxxx 4e. latch data 0110111_00000000 1110111_00000000 0110111_00000000 xxxxxxx_xxxxxxxx xxxxxxx_xxxxxxxx xxxxxxx_xxxxxxxx (1) 4f. write eeprom page 0110011_00000000 0110001_00000000 0110011_00000000 0110011_00000000 xxxxxxx_xxxxxxxx xxxxxxx_xxxxxxxx xxxxxxx_xxxxxxxx xxxxxxx_xxxxxxxx (1) 4g. poll for page write complete 0110011_00000000 xxxxx o x_xxxxxxxx (2) 5a. enter eeprom read 0100011_00000011 xxxxxxx_xxxxxxxx 5b. load address high byte 0000111_ aaaaaaaa xxxxxxx_xxxxxxxx (9) 5c. load address low byte 0000011_ bbbbbbbb xxxxxxx_xxxxxxxx 256 2513k?avr?07/09 atmega162/v 5d. read data byte 0110011_ bbbbbbbb 0110010_00000000 0110011_00000000 xxxxxxx_xxxxxxxx xxxxxxx_xxxxxxxx xxxxxxx_ oooooooo 6a. enter fuse write 0100011_01000000 xxxxxxx_xxxxxxxx 6b. load data low byte (6) 0010011_ iiiiiiii xxxxxxx_xxxxxxxx (3) 6c. write fuse extended byte 0111011_00000000 0111001_00000000 0111011_00000000 0111011_00000000 xxxxxxx_xxxxxxxx xxxxxxx_xxxxxxxx xxxxxxx_xxxxxxxx xxxxxxx_xxxxxxxx (1) 6d. poll for fuse write complete 0110111_00000000 xxxxx o x_xxxxxxxx (2) 6e. load data low byte (7) 0010011_ iiiiiiii xxxxxxx_xxxxxxxx (3) 6f. write fuse high byte 0110111_00000000 0110101_00000000 0110111_00000000 0110111_00000000 xxxxxxx_xxxxxxxx xxxxxxx_xxxxxxxx xxxxxxx_xxxxxxxx xxxxxxx_xxxxxxxx (1) 6g. poll for fuse write complete 0110111_00000000 xxxxx o x_xxxxxxxx (2) 6h. load data low byte (8) 0010011_ iiiiiiii xxxxxxx_xxxxxxxx (3) 6i. write fuse low byte 0110011_00000000 0110001_00000000 0110011_00000000 0110011_00000000 xxxxxxx_xxxxxxxx xxxxxxx_xxxxxxxx xxxxxxx_xxxxxxxx xxxxxxx_xxxxxxxx (1) 6j. poll for fuse write complete 0110011_00000000 xxxxx o x_xxxxxxxx (2) 7a. enter lock bit write 0100011_00100000 xxxxxxx_xxxxxxxx 7b. load data byte (9) 0010011_11 iiiiii xxxxxxx_xxxxxxxx (4) 7c. write lock bits 0110011_00000000 0110001_00000000 0110011_00000000 0110011_00000000 xxxxxxx_xxxxxxxx xxxxxxx_xxxxxxxx xxxxxxx_xxxxxxxx xxxxxxx_xxxxxxxx (1) 7d. poll for lock bit write complete 0110011_00000000 xxxxx o x_xxxxxxxx (2) 8a. enter fuse/lock bit read 0100011_00000100 xxxxxxx_xxxxxxxx 8b. read fuse extended byte (6) 0111010_00000000 0111111_00000000 xxxxxxx_xxxxxxxx xxxxxxx_ oooooooo 8c. read fuse high byte (7) 0111110_00000000 0111111_00000000 xxxxxxx_xxxxxxxx xxxxxxx_ oooooooo 8d. read fuse low byte (8) 0110010_00000000 0110011_00000000 xxxxxxx_xxxxxxxx xxxxxxx_ oooooooo 8e. read lock bits (9) 0110110_00000000 0110111_00000000 xxxxxxx_xxxxxxxx xxxxxxx_xx oooooo (5) table 111. jtag programming instruction set (continued) instruction tdi sequen ce tdo sequence notes 257 2513k?avr?07/09 atmega162/v notes: 1. this command sequence is not required if the seven m sb are correctly set by the previous command sequence (which is normally the case). 2. repeat until o = ?1?. 3. set bits to ?0? to program the corresponding fuse, ?1? to unprogram the fuse. 4. set bits to ?0? to program the corresponding lock bit, ?1? to leave the lock bit unchanged. 5. ?0? = programmed, ?1? = unprogrammed. 6. the bit mapping for fuses extended byte is listed in table 98 on page 232 . 7. the bit mapping for fuses high byte is listed in table 99 on page 233 . 8. the bit mapping for fuses low byte is listed in table 100 on page 233 . 9. the bit mapping for lock bits byte is listed in table 96 on page 231 . 10. address bits exceeding pcmsb and eeamsb ( table 105 and table 106 ) are don?t care note: a = address high bits b = address low bits h = 0 ? low byte, 1 ? high byte o = data out i = data in x = don?t care 8f. read fuses and lock bits 0111010_00000000 0111110_00000000 0110010_00000000 0110110_00000000 0110111_00000000 xxxxxxx_xxxxxxxx xxxxxxx_ oooooooo xxxxxxx_ oooooooo xxxxxxx_ oooooooo xxxxxxx_ oooooooo (5) fuse ext. byte fuse high byte fuse low byte lock bits 9a. enter signature byte read 0100011_00001000 xxxxxxx_xxxxxxxx 9b. load address byte 0000011_ bbbbbbbb xxxxxxx_xxxxxxxx 9c. read signature byte 0110010_00000000 0110011_00000000 xxxxxxx_xxxxxxxx xxxxxxx_ oooooooo 10a. enter calibration byte read 0100011_00001000 xxxxxxx_xxxxxxxx 10b. load address byte 0000011_ bbbbbbbb xxxxxxx_xxxxxxxx 10c. read calibration byte 0110110_00000000 0110111_00000000 xxxxxxx_xxxxxxxx xxxxxxx_ oooooooo 11a. load no operation command 0100011_00000000 0110011_00000000 xxxxxxx_xxxxxxxx xxxxxxx_xxxxxxxx table 111. jtag programming instruction set (continued) instruction tdi sequen ce tdo sequence notes 258 2513k?avr?07/09 atmega162/v figure 110. state machine sequence for changing/reading the data word virtual flash page load register the virtual flash page load register is a virtual scan chain with length equal to the number of bits in one flash page. internally the shift regist er is 8-bit, and the data are automatically trans- ferred to the flash page buffer byte-by-byte. shift in all instruction words in the page, starting with the lsb of the first instruction in the page and ending with the msb of the last instruction in the page. this provides an efficient way to load the entire flash page buffer before executing page write. test-logic-reset run-test/idle shift-dr exit1-dr pause-dr exit2-dr update-dr select-ir scan capture-ir shift-ir exit1-ir pause-ir exit2-ir update-ir select-dr scan capture-dr 0 1 0 11 1 00 00 11 1 0 1 1 0 1 0 0 1 0 1 1 0 1 0 0 0 0 1 1 259 2513k?avr?07/09 atmega162/v figure 111. virtual flash page load register virtual flash page read register the virtual flash page read register is a virtual scan chain with length equal to the number of bits in one flash page plus eight. internally the shift register is 8-bit, and the data are automati- cally transferred from the flash data page by te-by-byte. the first eight cycles are used to transfer the first byte to the internal shift regist er, and the bits that are shifted out during these right cycles should be ignored. following this initia lization, data are shifted out starting with the lsb of the first instruction in the page and ending with the msb of the last instruction in the page. this provides an efficient way to read one full flash page to verify programming. tdi tdo d a t a flash eeprom fuses lock bits strobes address state machine 260 2513k?avr?07/09 atmega162/v figure 112. virtual flash page read register programming algorithm all references below of type ?1a?, ?1b?, and so on, refer to table 111 . entering programming mode 1. enter jtag instruction avr_reset and shift one in the reset register. 2. enter instruction prog_enable and shift 1010_0011_0111_0000 in the programming enable register. leaving programming mode 1. enter jtag instruction prog_commands. 2. disable all programming instructions by using no operation instruction 11a. 3. enter instruction prog_enable and shift 0000_0000_0000_0000 in the programming enable register. 4. enter jtag instruction avr_reset and shift 0 in the reset register. performing chip erase 1. enter jtag instruction prog_commands. 2. start chip erase using pr ogramming instruction 1a. 3. poll for chip erase complete using prog ramming instruction 1b, or wait for t wlrh_ce (refer to table 107 on page 244 ). programming the flash before programming the flash a chip erase must be performed. see ?performing chip erase? on page 260 . 1. enter jtag instruction prog_commands. 2. enable flash write using programming instruction 2a. 3. load address high byte using programming instruction 2b. 4. load address low byte using programming instruction 2c. 5. load data using programming instructions 2d, 2e and 2f. 6. repeat steps 4 and 5 for all instruction words in the page. tdi tdo d a t a flash eeprom fuses lock bits strobes address state machine 261 2513k?avr?07/09 atmega162/v 7. write the page using programming instruction 2g. 8. poll for flash write complete using programming instruction 2h, or wait for t wlrh_flash (refer to table 107 on page 244 ). 9. repeat steps 3 to 7 until all data have been programmed. a more efficient data transfer can be achieved using the prog_pageload instruction: 1. enter jtag instruction prog_commands. 2. enable flash write using programming instruction 2a. 3. load the page address using programming instructions 2b and 2c. pcword (refer to table 105 on page 236 ) is used to address within one page and must be written as 0. 4. enter jtag instruction prog_pageload. 5. load the entire page by shifting in all instruction words in the page, starting with the lsb of the first instruction in the page and ending with the msb of the last instruction in the page. 6. enter jtag instruction prog_commands. 7. write the page using programming instruction 2g. 8. poll for flash write complete using programming instruction 2h, or wait for t wlrh_flash (refer to table 107 on page 244 ). 9. repeat steps 3 to 8 until all data have been programmed. reading the flash 1. enter jtag instruction prog_commands. 2. enable flash read using programming instruction 3a. 3. load address using programming instructions 3b and 3c. 4. read data using programming instruction 3d. 5. repeat steps 3 and 4 until all data have been read. a more efficient data transfer can be ac hieved using the prog_pageread instruction: 1. enter jtag instruction prog_commands. 2. enable flash read using programming instruction 3a. 3. load the page address using programming instructions 3b and 3c. pcword (refer to table 105 on page 236 ) is used to address within one page and must be written as 0. 4. enter jtag instruction prog_pageread. 5. read the entire page by shifting out all instruction words in the page, starting with the lsb of the first instruction in the page and ending with the msb of the last instruction in the page. remember that the first 8 bits shifted out should be ignored. 6. enter jtag instruction prog_commands. 7. repeat steps 3 to 6 until all data have been read. 262 2513k?avr?07/09 atmega162/v programming the eeprom before programming the eeprom a chip erase must be performed. see ?performing chip erase? on page 260 . 1. enter jtag instruction prog_commands. 2. enable eeprom write using programming instruction 4a. 3. load address high byte using programming instruction 4b. 4. load address low byte using programming instruction 4c. 5. load data using programming instructions 4d and 4e. 6. repeat steps 4 and 5 for all data bytes in the page. 7. write the data using programming instruction 4f. 8. poll for eeprom write complete using prog ramming instruction 4g, or wait for t wlrh (refer to table 107 on page 244 ). 9. repeat steps 3 to 8 until all data have been programmed. note: the prog_pageload instruction c an not be used when programming the eeprom reading the eeprom 1. enter jtag instruction prog_commands. 2. enable eeprom read using programming instruction 5a. 3. load address using programming instructions 5b and 5c. 4. read data using programming instruction 5d. 5. repeat steps 3 and 4 until all data have been read. note: the prog_pageread instruction ca n not be used when reading the eeprom programming the fuses 1. enter jtag instruction prog_commands. 2. enable fuse write using programming instruction 6a. 3. load data low byte using programming instructions 6b. a bit value of ?0? will program the corresponding fuse, a ?1 ? will unprogram the fuse. 4. write fuse extended byte using programming instruction 6c. 5. poll for fuse write complete using prog ramming instruction 6d, or wait for t wlrh (refer to table 107 on page 244 ). 6. load data low byte using pr ogramming instructions 6e. a bit value of ?0? will program the corresponding fuse, a ?1 ? will unprogram the fuse. 7. write fuse high byte using programming instruction 6f. 8. poll for fuse write complete using prog ramming instruction 6g, or wait for t wlrh (refer to table 107 on page 244 ). 9. load data low byte using programming inst ructions 6h. a ?0? will program the fuse, a ?1? will unprogram the fuse. 10. write fuse low byte using programming instruction 6i. 11. poll for fuse write complete using pr ogramming instruction 6j, or wait for t wlrh (refer to table 107 on page 244 ). programming the lock bits 1. enter jtag instruction prog_commands. 2. enable lock bit write using programming instruction 7a. 3. load data using programmin g instructions 7b. a bit value of ?0? will program the corre- sponding lock bit, a ?1? will le ave the lock bit unchanged. 4. write lock bits using programming instruction 7c. 5. poll for lock bit write complete using programming instruction 7d, or wait for t wlrh (refer to table 107 on page 244 ). 263 2513k?avr?07/09 atmega162/v reading the fuses and lock bits 1. enter jtag instruction prog_commands. 2. enable fuse/lock bit read using programming instruction 8a. 3. to read all fuses and lock bits, use programming instruction 8f. to only read fuse extended byte, use programming instruction 8b. to only read fuse high byte, use programming instruction 8c. to only read fuse low byte, use programming instruction 8d. to only read lock bits, use programming instruction 8e. reading the signature bytes 1. enter jtag instruction prog_commands. 2. enable signature byte read using programming instruction 9a. 3. load address 0x00 using programming instruction 9b. 4. read first signature byte using programming instruction 9c. 5. repeat steps 3 and 4 with address 0x01 and address 0x02 to read the second and third signature bytes, respectively. reading the calibration byte 1. enter jtag instruction prog_commands. 2. enable calibration byte read using programming instruction 10a. 3. load address 0x00 using programming instruction 10b. 4. read the calibration byte using programming instruction 10c. 264 2513k?avr?07/09 atmega162/v electrical characteristics dc characteristics absolute maximum ratings* operating temperature.................................. -55 c to +125 c *notice: stresses beyond those listed under ?absolute maximum ratings? may cause permanent dam- age to the device. this is a stress rating only and functional operation of the device at these or other conditions beyond those indicated in the operational sections of this specification is not implied. exposure to absolute maximum rating conditions for extended periods may affect device reliability. storage temperature ..................................... -65c to +150c voltage on any pin except reset with respect to ground ................................-0.5v to v cc +0.5v voltage on reset with respect to ground......-0.5v to +13.0v maximum operating voltage ............................................ 6.0v dc current per i/o pin ............................................... 40.0 ma dc current v cc and gnd pins.......................200.0 ma pdip, 400 ma tqfp/mlf t a = -40 c to 85 c, v cc = 1.8v to 5.5v (unless otherwise noted) symbol parameter condition min. typ. max. units v il input low voltage, except xtal1 and reset pin v cc = 1.8 - 2.4v v cc = 2.4 - 5.5v -0.5 -0.5 0.2 v cc (1) 0.3 v cc (1) v v ih input high voltage, except xtal1 and reset pin v cc = 1.8 - 2.4v v cc = 2.4 - 5.5v 0.7 v cc (2) 0.6 v cc (2) v cc + 0.5 v cc + 0.5 v v il1 input low voltage, xtal1 pin v cc = 1.8 - 5.5v -0.5 0.1 v cc (1) v v ih1 input high voltage, xtal1 pin v cc = 1.8 - 2.4v v cc = 2.4 - 5.5v 0.8 v cc (2) 0.7 v cc (2) v cc + 0.5 v cc + 0.5 v v il2 input low voltage, reset pin v cc = 1.8 - 5.5v -0.5 0.2 v cc v v ih2 input high voltage, reset pin v cc = 1.8 - 5.5v 0.9 v cc (2) v cc + 0.5 v v ol output low voltage (3) , ports a, b, c, d, and e i ol = 20 ma, v cc = 5v i ol = 10 ma, v cc = 3v 0.7 0.5 v v v oh output high voltage (4) , ports a, b, c, d, and e i ol = -20 ma, v cc = 5v i ol = -10 ma, v cc = 3v 4.2 2.3 v v i il input leakage current i/o pin vcc = 5.5 v, p i n l o w (absolute value) 1a i ih input leakage current i/o pin vcc = 5.5 v, pin high (absolute value) 1a r rst reset pull-up resistor 30 60 k r pu i/o pin pull-up resistor 20 50 k 265 2513k?avr?07/09 atmega162/v notes: 1. ?max? means the highest value where the pin is guaranteed to be read as low 2. ?min? means the lowest value where t he pin is guaranteed to be read as high 3. although each i/o port can sink more than the test conditi ons (20 ma at vcc = 5v, 10 ma at vcc = 3v) under steady state conditions (non-transient), th e following must be observed: pdip package: 1] the sum of all iol, for all ports, should not exceed 200 ma. 2] the sum of all iol, for port b0 - b7, d0 - d7, and xtal2, should not exceed 100 ma. 3] the sum of all iol, for ports a0 - a7, e0 - e2, c0 - c7, should not exceed 100 ma. tqfp and qfn/mlf package: 1] the sum of all iol, for all ports, should not exceed 400 ma. 2] the sum of all iol, for ports b0 - b7, d0 - d7, and xtal2, should not exceed 200 ma. 3] the sum of all iol, for ports c0 - c7 and e1 - e2, should not exceed 200 ma. 4] the sum of all iol, for ports a0 - a7 and e0, should not exceed 200 ma. if iol exceeds the test condition, vol may exceed the related specification. pins are not guar anteed to sink current greater than the listed test condition. 4. although each i/o port can source more than the test condition s (20 ma at vcc = 5v, 10 ma at vcc = 3v) under steady state conditions (non-transient), th e following must be observed: pdip package: 1] the sum of all ioh, for a ll ports, should not exceed 200 ma. 2] the sum of all ioh, for port b0 - b7, d0 - d7, and xtal2, should not exceed 100 ma. 3] the sum of all ioh, for ports a0 - a7, e0 - e2, c0 - c7, should not exceed 100 ma. tqfp and mlf package: 1] the sum of all ioh, for a ll ports, should not exceed 400 ma. 2] the sum of all ioh, for ports b0 - b7, d0 - d7, and xtal2, should not exceed 200 ma. 3] the sum of all ioh, for ports c0 - c7 and e1 - e2, should not exceed 200 ma. 4] the sum of all ioh, for ports a0 - a7 and e0, should not exceed 200 ma. i cc power supply current active 1 mhz, v cc = 2v (atmega162v) 0.8 ma active 4 mhz, v cc = 3v (atmega162/v) 5ma active 8 mhz, v cc = 5v (atmega162) 16 ma idle 1 mhz, v cc = 2v (atmega162v) 0.3 ma idle 4 mhz, v cc = 3v (atmega162/v) 2ma idle 8 mhz, v cc = 5v (atmega162) 8ma power-down mode wdt enabled, v cc = 3.0v < 10 14 a wdt disabled, v cc = 3.0v < 1.5 2 a v acio analog comparator input offset voltage v cc = 5v v in = v cc /2 < 10 40 mv i aclk analog comparator input leakage current v cc = 5v v in = v cc /2 -50 50 na t acpd analog comparator propagation delay v cc = 2.7v v cc = 4.0v 750 500 ns t a = -40 c to 85 c, v cc = 1.8v to 5.5v (unless otherwise noted) (continued) symbol parameter condition min. typ. max. units 266 2513k?avr?07/09 atmega162/v if ioh exceeds the test condition, voh may exceed the rela ted specification. pins are not guaranteed to source current greater than the listed test condition. figure 113. absolute maximum frequency as a function of vcc, atmega162v figure 114. absolute maximum frequency as a function of vcc, atmega162 frequency 8 mhz 16 mhz 1 mhz vcc 1.8v 2.4v 5.5v 2.7v 4.5v safe operating area frequency 8 mhz 16 mhz 1 mhz vcc 1.8v 2.4v 5.5v 2.7v 4.5v safe operating area 267 2513k?avr?07/09 atmega162/v external clock drive waveforms figure 115. external clock drive waveforms external clock drive v il1 v ih1 table 112. external clock drive symbol parameter v cc = 1.8 - 5.5v v cc =2.7 - 5.5v v cc = 4.5 - 5.5v units min. max. min. max. min. max. 1/t clcl oscillator frequency 0108016mhz t clcl clock period 1000 125 62.5 ns t chcx high time 400 50 25 ns t clcx low time 400 50 25 ns t clch rise time 2.0 1.6 0.5 s t chcl fall time 2.0 1.6 0.5 s t clcl change in period from one clock cycle to the next 22 2% 268 2513k?avr?07/09 atmega162/v spi timing characteristics see figure 116 and figure 117 for details. note: 1. in spi programming mode, the minimum sck high/low period is: ? 2 t clcl for f ck < 12 mhz ? 3 t clcl for f ck > 12 mhz. figure 116. spi interface timing requirements (master mode) table 113. spi timing parameters description mode min typ max 1 sck period master see table 68 ns 2 sck high/low master 50% duty cycle 3 rise/fall time master 3.6 4 setup master 10 5 hold master 10 6 out to sck master 0.5 ? t sck 7 sck to out master 10 8 sck to out high master 10 9 ss low to out slave 15 10 sck period slave 4 ? t ck 11 sck high/low (1) slave 2 ? t ck 12 rise/fall time slave 1.6 s 13 setup slave 10 ns 14 hold slave t ck 15 sck to out slave 15 16 sck to ss high slave 20 17 ss high to tri-state slave 10 18 ss low to sck slave 2 ? t ck mo si (data output) sck (cpol = 1) mi so (data input) sck (cpol = 0) ss msb lsb lsb msb ... ... 61 22 3 45 8 7 269 2513k?avr?07/09 atmega162/v figure 117. spi interface timing requirements (slave mode) mi so (data output) sck (cpol = 1) mo si (data input) sck (cpol = 0) ss msb lsb lsb msb ... ... 10 11 11 12 13 14 17 15 9 x 16 18 270 2513k?avr?07/09 atmega162/v external data memory timing notes: 1. this assumes 50% clock duty cycl e. the half peri od is actually the high time of the external clock, xtal1. 2. this assumes 50% clock duty cycle. the half period is actually the low time of the external clock, xtal1. table 114. external data memory characteristics, 4.5 - 5.5 volts, no wait-state symbol parameter 8 mhz oscillator variable oscillator unit min max min max 01/t clcl oscillator frequency 0.0 16 mhz 1t lhll ale pulse width 115 1.0t clcl -10 ns 2t avll address valid a to ale low 57.5 0.5t clcl -5 (1) ns 3a t llax_st address hold after ale low, write access 55 ns 3b t llax_ld address hold after ale low, read access 55 ns 4t avllc address valid c to ale low 57.5 0.5t clcl -5 (1) ns 5t avrl address valid to rd low 115 1.0t clcl -10 ns 6t avwl address valid to wr low 115 1.0t clcl -10 ns 7t llwl ale low to wr low 47.5 67.5 0.5t clcl -15 (2) 0.5t clcl +5 (2) ns 8t llrl ale low to rd low 47.5 67.5 0.5t clcl -15 (2) 0.5t clcl +5 (2) ns 9t dvrh data setup to rd high 40 40 ns 10 t rldv read low to data valid 75 1.0t clcl -50 ns 11 t rhdx data hold after rd high 0 0 ns 12 t rlrh rd pulse width 115 1.0t clcl -10 ns 13 t dvwl data setup to wr low 42.5 0.5t clcl -20 (1) ns 14 t whdx data hold after wr high 115 1.0t clcl -10 ns 15 t dvwh data valid to wr high 125 1.0t clcl ns 16 t wlwh wr pulse width 115 1.0t clcl -10 ns table 115. external data memory characteristics, 4.5 - 5.5 volts, 1 cycle wait-state symbol parameter 8 mhz oscillator variable oscillator unit min max min max 01/t clcl oscillator frequency 0.0 16 mhz 10 t rldv read low to data valid 200 2.0t clcl -50 ns 12 t rlrh rd pulse width 240 2.0t clcl -10 ns 15 t dvwh data valid to wr high 240 2.0t clcl ns 16 t wlwh wr pulse width 240 2.0t clcl -10 ns 271 2513k?avr?07/09 atmega162/v table 116. external data memory characteristics, 4.5 - 5.5 volts, srwn1 = 1, srwn0 = 0 symbol parameter 4 mhz oscillator variable oscillator unit min max min max 01/t clcl oscillator frequency 0.0 16 mhz 10 t rldv read low to data valid 325 3.0t clcl -50 ns 12 t rlrh rd pulse width 365 3.0t clcl -10 ns 15 t dvwh data valid to wr high 375 3.0t clcl ns 16 t wlwh wr pulse width 365 3.0t clcl -10 ns table 117. external data memory characteristics, 4.5 - 5.5 volts, srwn1 = 1, srwn0 = 1 symbol parameter 4 mhz oscillator variable oscillator unit min max min max 01/t clcl oscillator frequency 0.0 16 mhz 10 t rldv read low to data valid 325 3.0t clcl -50 ns 12 t rlrh rd pulse width 365 3.0t clcl -10 ns 14 t whdx data hold after wr high 240 2.0t clcl -10 ns 15 t dvwh data valid to wr high 375 3.0t clcl ns 16 t wlwh wr pulse width 365 3.0t clcl -10 ns table 118. external data memory characteristics, 2.7 - 5.5 volts, no wait-state symbol parameter 4 mhz oscillator variable oscillator unit min max min max 01/t clcl oscillator frequency 0.0 8 mhz 1t lhll ale pulse width 235 t clcl -15 ns 2t avll address valid a to ale low 115 0.5t clcl -10 (1) ns 3a t llax_st address hold after ale low, write access 55 ns 3b t llax_ld address hold after ale low, read access 55 ns 4t avllc address valid c to ale low 115 0.5t clcl -10 (1) ns 5t avrl address valid to rd low 235 1.0t clcl -15 ns 6t avwl address valid to wr low 235 1.0t clcl -15 ns 7t llwl ale low to wr low 115 130 0.5t clcl -10 (2) 0.5t clcl +5 (2) ns 8t llrl ale low to rd low 115 130 0.5t clcl -10 (2) 0.5t clcl +5 (2) ns 9t dvrh data setup to rd high 45 45 ns 10 t rldv read low to data valid 190 1.0t clcl -60 ns 11 t rhdx data hold after rd high 0 0 ns 272 2513k?avr?07/09 atmega162/v notes: 1. this assumes 50% clock duty cycl e. the half peri od is actually the high time of the external clock, xtal1. 2. this assumes 50% clock duty cycle. the half period is actually the low time of the external clock, xtal1. 12 t rlrh rd pulse width 235 1.0t clcl -15 ns 13 t dvwl data setup to wr low 105 0.5t clcl -20 (1) ns 14 t whdx data hold after wr high 235 1.0t clcl -15 ns 15 t dvwh data valid to wr high 250 1.0t clcl ns 16 t wlwh wr pulse width 235 1.0t clcl -15 ns table 118. external data memory characteristics, 2.7 - 5.5 volts, no wait-state (continued) symbol parameter 4 mhz oscillator variable oscillator unit min max min max table 119. external data memory characteristics, 2.7 - 5.5 volts, srwn1 = 0, srwn0 = 1 symbol parameter 4 mhz oscillator variable oscillator unit min max min max 01/t clcl oscillator frequency 0.0 8 mhz 10 t rldv read low to data valid 440 2.0t clcl -60 ns 12 t rlrh rd pulse width 485 2.0t clcl -15 ns 15 t dvwh data valid to wr high 500 2.0t clcl ns 16 t wlwh wr pulse width 485 2.0t clcl -15 ns table 120. external data memory characteristics, 2.7 - 5.5 volts, srwn1 = 1, srwn0 = 0 symbol parameter 4 mhz oscillator variable oscillator unit min max min max 01/t clcl oscillator frequency 0.0 8 mhz 10 t rldv read low to data valid 690 3.0t clcl -60 ns 12 t rlrh rd pulse width 735 3.0t clcl -15 ns 15 t dvwh data valid to wr high 750 3.0t clcl ns 16 t wlwh wr pulse width 735 3.0t clcl -15 ns table 121. external data memory characteristics, 2.7 - 5.5 volts, srwn1 = 1, srwn0 = 1 symbol parameter 4 mhz oscillator variable oscillator unit min max min max 01/t clcl oscillator frequency 0.0 8 mhz 10 t rldv read low to data valid 690 3.0t clcl -60 ns 12 t rlrh rd pulse width 735 3.0t clcl -15 ns 14 t whdx data hold after wr high 485 2.0t clcl -15 ns 15 t dvwh data valid to wr high 750 3.0t clcl ns 16 t wlwh wr pulse width 735 3.0t clcl -15 ns 273 2513k?avr?07/09 atmega162/v figure 118. external memory timing (srwn1 = 0, srwn0 = 0 figure 119. external memory timing (srwn1 = 0, srwn0 = 1) ale t1 t2 t3 write read wr t4 a15:8 address prev. addr. da7:0 address data prev. data xx rd da7:0 (xmbk = 0) data address system clock (clk cpu ) 1 4 2 7 6 3a 3b 5 8 12 16 13 10 11 14 15 9 ale t1 t2 t3 write read wr t5 a15:8 address prev. addr. da7:0 address data prev. data xx rd da7:0 (xmbk = 0) data address system clock (clk cpu ) 1 4 2 7 6 3a 3b 5 8 12 16 13 10 11 14 15 9 t4 274 2513k?avr?07/09 atmega162/v figure 120. external memory timing (srwn1 = 1, srwn0 = 0) figure 121. external memory timing (srwn1 = 1, srwn0 = 1) (1) note: 1. the ale pulse in the last period (t4 - t7) is only present if the next instruction accesses the ram (internal or external). ale t1 t2 t3 write read wr t6 a15:8 address prev. addr. da7:0 address data prev. data xx rd da7:0 (xmbk = 0) data address system clock (clk cpu ) 1 4 2 7 6 3a 3b 5 8 12 16 13 10 11 14 15 9 t4 t5 ale t1 t2 t3 write read wr t7 a15:8 address prev. addr. da7:0 address data prev. data xx rd da7:0 (xmbk = 0) data address system clock (clk cpu ) 1 4 2 7 6 3a 3b 5 8 12 16 13 10 11 14 15 9 t4 t5 t6 275 2513k?avr?07/09 atmega162/v atmega162 typical characteristics the following charts show typical behavior. t hese figures are not tested during manufacturing. all current consumption measurements are performed with all i/o pins configured as inputs and with internal pull-ups enabled. a sine wave generator with rail-to-rail output is used as clock source. the cksel fuse s are programmed to se lect external clock. the power consumption in power-down mode is independent of clock selection. the current consumption is a function of several factors such as: operating voltage, operating frequency, loading of i/o pins, switching rate of i/o pins, code executed and ambient tempera- ture. the dominating factors are operating voltage and frequency. the current drawn from capacitive loaded pins may be estimated (for one pin) as c l * v cc *f where c l = load capacitance, v cc = operating voltage and f = average switching frequency of i/o pin. the parts are characterized at frequencies higher than test limits. parts are not guaranteed to function properly at frequencies higher than the ordering code indicates. the difference between current consumption in power-down mode with watchdog timer enabled and power-down mode with watchdog timer disabled represents the differential cur- rent drawn by the watchdog timer. active supply current figure 122. active supply current vs. frequency (0.1 - 1.0 mhz) active supply current vs. frequency 0.1 - 1.0 mhz 0 0.5 1 1.5 2 2.5 3 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 frequency (mhz) i cc (ma) 5.5v 4.5v 4.0v 3.3v 2.7v 1.8v 5.0v 276 2513k?avr?07/09 atmega162/v figure 123. active supply current vs. frequency (1 - 20 mhz) figure 124. active supply current vs. v cc (internal rc oscillator, 8 mhz) active supply current vs. frequency 1- 20 mhz 0 5 10 15 20 25 30 35 40 45 02468101214161820 frequency (mhz) i cc (ma) 5.5v 4.5v 4.0v 3.3v 2.7v 1.8v 5.0v active supply current vs. v cc internal rc oscillator, 8 mhz 0 2 4 6 8 10 12 14 16 18 20 1.5 2 2.5 3 3.5 4 4.5 5 5.5 v cc (v) i cc (ma) 85c 25c -40c 277 2513k?avr?07/09 atmega162/v figure 125. active supply current vs. v cc (32 khz external oscillator) idle supply current figure 126. idle supply current vs. frequency (0.1 - 1.0 mhz) active supply current vs. v cc 32khz external oscillator 0 50 100 150 200 250 300 1.5 2 2.5 3 3.5 4 4.5 5 5.5 v cc (v) i cc (ua) 25c 85c idle supply current vs. frequency 0.1 - 1.0 mhz 0 0.2 0.4 0.6 0.8 1 1.2 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 frequency (mhz) i cc (ma) 5.5v 4.5v 4.0v 3.3v 2.7v 1.8v 5.0v 278 2513k?avr?07/09 atmega162/v figure 127. idle supply current vs. frequency (1 - 20 mhz) figure 128. idle supply current vs. v cc (internal rc o scillator, 8 mhz) idle supply current vs. frequency 1 - 20 mhz 0 5 10 15 20 25 0 2 4 6 8 10 12 14 16 18 20 frequency (mhz) i cc (ma) 5.5v 4.5v 4.0v 3.3v 2.7v 1.8v 5.0v idle supply current vs. v cc internal rc oscillator, 8 mhz 0 1 2 3 4 5 6 7 8 9 1.5 2 2.5 3 3.5 4 4.5 5 5.5 v cc (v) i cc (ma) 85c 25c -40c 279 2513k?avr?07/09 atmega162/v figure 129. idle supply current vs. v cc (32 khz external oscillator) power-down supply current figure 130. power-down supply current vs. v cc (watchdog timer disabled) idle supply current vs. v cc 32khz external oscillator 0 10 20 30 40 50 60 70 1.5 2 2.5 3 3.5 4 4.5 5 5.5 v cc (v) i cc (ua) 85c 25c power-down supply current vs. v cc watchdog timer disabled 0 0.5 1 1.5 2 2.5 3 1.5 2 2.5 3 3.5 4 4.5 5 5.5 v cc (v) i cc (ua) 85c 25c -40c 280 2513k?avr?07/09 atmega162/v figure 131. power-down supply current vs. v cc (watchdog timer enabled) power-save supply current figure 132. power-save supply current vs. v cc (watchdog timer disabled) power-down supply current vs. v cc watchdog timer enabled 0 5 10 15 20 25 1.5 2 2.5 3 3.5 4 4.5 5 5.5 v cc (v) i cc (ua) 85c 25c -40c power-save supply current vs. v cc watchdog timer disabled 0 5 10 15 20 25 30 1.5 2 2.5 3 3.5 4 4.5 5 5.5 v cc (v) i cc (ua) 85c 25c 281 2513k?avr?07/09 atmega162/v standby supply current figure 133. standby supply current vs. v cc (455 khz resonator, watchdog timer disabled) figure 134. standby supply current vs. v cc (1 mhz resonator, watchdog timer disabled) standby supply current vs. v cc 455 khz resonator, watchdog timer disabled 0 10 20 30 40 50 60 70 1.5 2 2.5 3 3.5 4 4.5 5 5.5 v cc (v) i cc (ua) standby supply current vs. v cc 1 mhz resonator, watchdog timer disabled 0 10 20 30 40 50 60 1.5 2 2.5 3 3.5 4 4.5 5 5.5 v cc (v) i cc (ua) 282 2513k?avr?07/09 atmega162/v figure 135. standby supply current vs. v cc (2 mhz resonator, watchdog timer disabled) figure 136. standby supply current vs. v cc (2 mhz xtal, watchdog timer disabled) standby supply current vs. v cc 2 mhz xtal, watchdog timer disabled 0 10 20 30 40 50 60 70 80 90 1.5 2 2.5 3 3.5 4 4.5 5 5.5 v cc (v) i cc (ua) standby supply current vs. v cc 2 mhz xtal, watchdog timer disabled 0 10 20 30 40 50 60 70 80 90 1.5 2 2.5 3 3.5 4 4.5 5 5.5 v cc (v) i cc (ua) 283 2513k?avr?07/09 atmega162/v figure 137. standby supply current vs. v cc (4 mhz resonator, watchdog timer disabled) figure 138. standby supply current vs. v cc (4 mhz xtal, watchdog timer disabled) standby supply current vs. v cc 4 mhz resonator, watchdog timer disabled 0 20 40 60 80 100 120 140 1.5 2 2.5 3 3.5 4 4.5 5 5.5 v cc (v) i cc (ua) standby supply current vs. v cc 4 mhz xtal, watchdog timer disabled 0 20 40 60 80 100 120 140 1.5 2 2.5 3 3.5 4 4.5 5 5.5 v cc (v) i cc (ua) 284 2513k?avr?07/09 atmega162/v figure 139. standby supply current vs. v cc (6 mhz resonator, watchdog timer disabled) figure 140. standby supply current vs. v cc (6 mhz xtal, watchdog timer disabled) standby supply current vs. v cc 6 mhz resonator, watchdog timer disabled 0 20 40 60 80 100 120 140 160 180 1.5 2 2.5 3 3.5 4 4.5 5 5.5 v cc (v) i cc (ua) standby supply current vs. v cc 6 mhz xtal, watchdog timer disabled 0 20 40 60 80 100 120 140 160 180 200 1.5 2 2.5 3 3.5 4 4.5 5 5.5 v cc (v) i cc (ua) 285 2513k?avr?07/09 atmega162/v pin pull-up figure 141. i/o pin pull-up resistor current vs. input voltage (v cc = 5v) figure 142. i/o pin pull-up resistor current vs. input voltage (v cc = 2.7v) i/o pin pull-up resistor current vs. input voltage vcc = 5v 0 20 40 60 80 100 120 140 160 012345 v io (v) i io (ua) 85c 25c -40c 6 i/o pin pull-up resistor current vs. input voltage vcc = 2.7v 0 10 20 30 40 50 60 70 80 0 0.5 1 1.5 2 2.5 3 v io (v) i io (ua) 85c 25c -40c 286 2513k?avr?07/09 atmega162/v figure 143. i/o pin pull-up resistor current vs. input voltage (v cc = 1.8v) figure 144. reset pull-up resistor current vs. reset pin voltage (v cc = 5v) i/o pin pull-up resistor current vs. input voltage vcc = 1.8v 0 10 20 30 40 50 60 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 v op (v) i op (ua) 85c 25c -40c reset pull-up resistor current vs. reset pin voltage vcc = 5v 0 20 40 60 80 100 120 012345 v reset (v) i reset (ua) -40c 25c 85c 6 287 2513k?avr?07/09 atmega162/v figure 145. reset pull-up resistor current vs. reset pin voltage (v cc = 2.7v) figure 146. reset pull-up resistor current vs. reset pin voltage (v cc = 1.8v) reset pull-up resistor current vs. reset pin voltage vcc = 2.7v 0 10 20 30 40 50 60 0 0.5 1 1.5 2 2.5 3 v reset (v) i reset (ua) -40c 25c 85c reset pull-up resistor current vs. reset pin voltage vcc = 1.8v 0 5 10 15 20 25 30 35 40 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 v reset (v) i reset (ua) -40c 25c 85c 288 2513k?avr?07/09 atmega162/v pin driver strength figure 147. i/o pin source current vs. output voltage (v cc = 5v) figure 148. i/o pin source current vs. output voltage (v cc = 2.7v) i/o pin source current vs. output voltage vcc = 5v 0 10 20 30 40 50 60 70 80 90 012345 v oh (v) i oh (ma) 85c 25c -40c 6 i/o pin source current vs. output voltage vcc = 2.7v 0 5 10 15 20 25 30 0 0.5 1 1.5 2 2.5 3 v oh (v) i oh (ma) 85c 25c -40c 289 2513k?avr?07/09 atmega162/v figure 149. i/o pin source current vs. output voltage (v cc = 1.8v) figure 150. i/o pin sink current vs. output voltage (v cc = 5v) i/o pin source current vs. output voltage vcc = 1.8v 0 1 2 3 4 5 6 7 8 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 v oh (v) i oh (ma) 85c 25c -40c i/o pin sink current vs. output voltage vcc = 5v 0 10 20 30 40 50 60 70 80 90 0 0.5 1 1.5 2 2.5 v ol (v) i ol (ma) 85c 25c -40c 290 2513k?avr?07/09 atmega162/v figure 151. i/o pin sink current vs. output voltage (v cc = 2.7v) figure 152. i/o pin sink current vs. output voltage (v cc = 1.8v) i/o pin sink current vs. output voltage vcc = 2.7v 0 5 10 15 20 25 30 35 0 0.5 1 1.5 2 2.5 v ol (v) i ol (ma) 85c 25c -40c i/o pin sink current vs. output voltage vcc = 1.8v 0 2 4 6 8 10 12 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 v ol (v) i ol (ma) 85c 25c -40c 291 2513k?avr?07/09 atmega162/v pin thresholds and hysteresis figure 153. i/o pin input threshold voltage vs. v cc (v ih , i/o pin read as ?1?) figure 154. i/o pin input threshold voltage vs. v cc (v il , i/o pin read as ?0?) i/o pin input threshold voltage vs. v cc vih, i/o pin read as '1' 0 0.5 1 1.5 2 2.5 3 1.522.533.544.555.5 v cc (v) threshold (v) 85c 25c -40c i/o pin input threshold voltage vs. v cc vil, i/o pin read as '0' 0 0.5 1 1.5 2 2.5 3 1.5 2 2.5 3 3.5 4 4.5 5 5.5 v cc (v) threshold (v) 85c 25c -40c 292 2513k?avr?07/09 atmega162/v figure 155. i/o pin input hysteresis vs. v cc figure 156. reset input threshold voltage vs. v cc (v ih , reset pin read as ?1?) i/o pin input hysteresis vs. v cc 0 0.1 0.2 0.3 0.4 0.5 0.6 1.5 2 2.5 3 3.5 4 4.5 5 5.5 v cc (v) threshold (v) 85c 25c -40c reset input threshold voltage vs. v cc vih, reset pin read as '1' 0 0.5 1 1.5 2 2.5 3 1.5 2 2.5 3 3.5 4 4.5 5 5.5 v cc (v) threshold (v) 85c 25c -40c 293 2513k?avr?07/09 atmega162/v figure 157. reset input threshold voltage vs. v cc (v il , reset pin read as ?0?) figure 158. reset input pin hysteresis vs. v cc reset input threshold voltage vs. v cc vil, reset pin read as '0' 0 0.5 1 1.5 2 2.5 1.5 2 2.5 3 3.5 4 4.5 5 5.5 v cc (v) threshold (v) 85c 25c -40c reset input pin hysteresis vs. vcc 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 1.5 2 2.5 3 3.5 4 4.5 5 5.5 v cc (v) threshold (v) 85c 25c -40c 294 2513k?avr?07/09 atmega162/v bod thresholds and analog comparator offset figure 159. bod thresholds vs. temperature (bod level is 4.3v) figure 160. bod thresholds vs. temperature (bod level is 2.7v) bod thresholds vs. temperature bodlevel is 4.3v 4 4.1 4.2 4.3 4.4 4.5 4.6 -50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 temperature (?c) threshold (v) rising v cc falling v cc bod thresholds vs. temperature bodlevel is 2.7v 2.4 2.5 2.6 2.7 2.8 2.9 3 -50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 temperature (?c) threshold (v) rising v cc falling v cc 295 2513k?avr?07/09 atmega162/v figure 161. bod thresholds vs. temperature (bod level is 2.3v) figure 162. bod thresholds vs. temperature (bod level is 1.8v) bod thresholds vs. temperature bodlevel is 2.3v 2 2.1 2.2 2.3 2.4 2.5 2.6 -50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 temperature (?c) threshold (v) rising v cc falling v cc bod thresholds vs. temperature bodlevel is 1.8v 1.5 1.6 1.7 1.8 1.9 2 2.1 -50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 temperature (?c) threshold (v) rising v cc falling v cc 296 2513k?avr?07/09 atmega162/v figure 163. bandgap voltage vs. v cc figure 164. analog comparator offset voltage vs. common mode voltage (v cc = 5v) bandgap voltage vs. v cc 1.08 1.09 1.1 1.11 1.12 1.13 1.14 1.5 2 2.5 3 3.5 4 4.5 5 5.5 vcc (v) bandgap voltage (v) 85c 25c -40c analog comparator offset voltage vs. common mode voltage v cc = 5v 0 0.001 0.002 0.003 0.004 0.005 0.006 0.007 0.008 0.009 0.01 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 common mode voltage (v) comparator offset voltage (v) 85c 25c -40c 297 2513k?avr?07/09 atmega162/v figure 165. analog comparator offset voltage vs. common mode voltage (v cc =2.7v) internal oscillator speed figure 166. watchdog oscillator frequency vs. v cc analog comparator offset voltage vs. common mode voltage v cc = 2.7v -0.001 0 0.001 0.002 0.003 0.004 0.005 0.006 0 0.5 1 1.5 2 2.5 3 common mode voltage (v) comparator offset voltage (v) 85c 25c -40c watchdog oscillator frequency vs. v cc 1000 1050 1100 1150 1200 1250 1300 1.5 2 2.5 3 3.5 4 4.5 5 5.5 v cc (v) f rc (khz) 85c 25c -40c 298 2513k?avr?07/09 atmega162/v figure 167. calibrated 8 mhz rc oscillator frequen cy vs. temperature figure 168. calibrated 8 mhz rc o scillator frequency vs.v cc calibrated 8mhz rc oscillator frequency vs. temperature 7.5 7.6 7.7 7.8 7.9 8 8.1 8.2 8.3 8.4 -60 -40 -20 0 20 40 60 80 100 t a (?c) f rc (mhz) 4.0v 1.8v 5.5v 2.7v calibrated 8mhz rc oscillator frequency vs. v cc 6 6.5 7 7.5 8 8.5 9 9.5 10 1.5 2 2.5 3 3.5 4 4.5 5 5.5 v cc (v) f rc (mhz) 85 c 25 c -40 c 299 2513k?avr?07/09 atmega162/v figure 169. calibrated 8 mhz rc oscillator frequen cy vs. osccal value current consumption of peripheral units figure 170. brownout detector current vs. v cc calibrated 8mhz rc oscillator frequency vs. osccal value 4 6 8 10 12 14 16 0 163248648096112 osccal value f rc (mhz) brownout detector current vs. v cc -5 0 5 10 15 20 25 30 35 1.5 2 2.5 3 3.5 4 4.5 5 5.5 v cc (v) i cc (ua) 25 c -40 c 85 c 300 2513k?avr?07/09 atmega162/v figure 171. 32 khz tosc current vs. v cc (watchdog timer disabled) figure 172. watchdog timer current vs. v cc 32khz tosc current vs. v cc watchdog timer disabled 0 5 10 15 20 25 30 1.5 2 2.5 3 3.5 4 4.5 5 5.5 v cc (v) i cc (ua) 85 c 25 c watchdog timer current vs. v cc 0 2 4 6 8 10 12 14 16 18 20 1.5 2 2.5 3 3.5 4 4.5 5 5.5 v cc (v) i cc (ua) 85 c 25 c -40 c 301 2513k?avr?07/09 atmega162/v figure 173. analog comparator current vs. v cc figure 174. programming current vs. v cc analog comparator current vs. v cc 0 10 20 30 40 50 60 70 80 1.5 2 2.5 3 3.5 4 4.5 5 5.5 v cc (v) i cc (ua) 85 c 25 c -40 c programming current vs. vcc 0 5 10 15 20 25 1.5 2 2.5 3 3.5 4 4.5 5 5.5 v cc (v) i cc (ma) 85 c 25 c -40 c 302 2513k?avr?07/09 atmega162/v current consumption in reset and reset pulsewidth figure 175. reset supply current vs. frequency (0.1 - 1.0 mhz, excluding current through the reset pull-up) figure 176. reset supply current vs. frequency (1 - 20 mhz, excluding current through the reset pull-up) reset supply current vs. frequency 0.1 - 1.0 mhz, excluding current through the reset pullup 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 frequency (mhz) i cc (ma) 5.5v 4.5v 4.0v 3.3v 2.7v 1.8v 5.0v reset supply current vs. frequency 1 - 20 mhz, excluding current through the reset pullup 0 5 10 15 20 25 30 35 02468101214161820 frequency (mhz) i cc (ma) 5.5v 4.5v 4.0v 3.3v 2.7v 1.8v 5.0v 303 2513k?avr?07/09 atmega162/v figure 177. reset pulse width vs. v cc reset pulse width vs. v cc 0 500 1000 1500 2000 2500 1.5 2 2.5 3 3.5 4 4.5 5 5.5 v cc (v) pulsewidth (ns) 85 c 25 c -40 c 304 2513k?avr?07/09 atmega162/v register summary address name bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 page (0xff) reserved ? ? ? ? ? ? ? ? .. reserved ? ? ? ? ? ? ? ? (0x9e) reserved ? ? ? ? ? ? ? ? (0x9d) reserved ? ? ? ? ? ? ? ? (0x9c) reserved ? ? ? ? ? ? ? ? (0x9b) reserved ? ? ? ? ? ? ? ? (0x9a) reserved ? ? ? ? ? ? ? ? (0x99) reserved ? ? ? ? ? ? ? ? (0x98) reserved ? ? ? ? ? ? ? ? (0x97) reserved ? ? ? ? ? ? ? ? (0x96) reserved ? ? ? ? ? ? ? ? (0x95) reserved ? ? ? ? ? ? ? ? (0x94) reserved ? ? ? ? ? ? ? ? (0x93) reserved ? ? ? ? ? ? ? ? (0x92) reserved ? ? ? ? ? ? ? ? (0x91) reserved ? ? ? ? ? ? ? ? (0x90) reserved ? ? ? ? ? ? ? ? (0x8f) reserved ? ? ? ? ? ? ? ? (0x8e) reserved ? ? ? ? ? ? ? ? (0x8d) reserved ? ? ? ? ? ? ? ? (0x8c) reserved ? ? ? ? ? ? ? ? (0x8b) tccr3a com3a1 com3a0 com3b1 com3b0 foc3a foc3b wgm31 wgm30 131 (0x8a) tccr3b icnc3 ices3 ? wgm33 wgm32 cs32 cs31 cs30 128 (0x89) tcnt3h timer/counter3 ? counter register high byte 133 (0x88) tcnt3l timer/counter3 ? counter register low byte 133 (0x87) ocr3ah timer/counter3 ? output compare register a high byte 133 (0x86) ocr3al timer/counter3 ? output compare register a low byte 133 (0x85) ocr3bh timer/counter3 ? output compare register b high byte 133 (0x84) ocr3bl timer/counter3 ? output compare register b low byte 133 (0x83) reserved ? ? ? ? ? ? ? ? (0x82) reserved ? ? ? ? ? ? ? ? (0x81) icr3h timer/counter3 ? input capture register high byte 134 (0x80) icr3l timer/counter3 ? input capture register low byte 134 (0x7f) reserved ? ? ? ? ? ? ? ? (0x7e) reserved ? ? ? ? ? ? ? ? (0x7d) etimsk ? ? ticie3 ocie3a ocie3b toie3 ? ? 135 (0x7c) etifr ? ? icf3 ocf3a ocf3b tov3 ? ? 135 (0x7b) reserved ? ? ? ? ? ? ? ? (0x7a) reserved ? ? ? ? ? ? ? ? (0x79) reserved ? ? ? ? ? ? ? ? (0x78) reserved ? ? ? ? ? ? ? ? (0x77) reserved ? ? ? ? ? ? ? ? (0x76) reserved ? ? ? ? ? ? ? ? (0x75) reserved ? ? ? ? ? ? ? ? (0x74) reserved ? ? ? ? ? ? ? ? (0x73) reserved ? ? ? ? ? ? ? ? (0x72) reserved ? ? ? ? ? ? ? ? (0x71) reserved ? ? ? ? ? ? ? ? (0x70) reserved ? ? ? ? ? ? ? ? (0x6f) reserved ? ? ? ? ? ? ? ? (0x6e) reserved ? ? ? ? ? ? ? ? (0x6d) reserved ? ? ? ? ? ? ? ? (0x6c) pcmsk1 pcint15 pcint14 pcint13 p cint12 pcint11 pcint10 pcint9 pcint8 88 (0x6b) pcmsk0 pcint7 pcint6 pcint5 pcint4 pcint3 pcint2 pcint1 pcint0 88 (0x6a) reserved ? ? ? ? ? ? ? ? (0x69) reserved ? ? ? ? ? ? ? ? (0x68) reserved ? ? ? ? ? ? ? ? (0x67) reserved ? ? ? ? ? ? ? ? (0x66) reserved ? ? ? ? ? ? ? ? (0x65) reserved ? ? ? ? ? ? ? ? (0x64) reserved ? ? ? ? ? ? ? ? (0x63) reserved ? ? ? ? ? ? ? ? (0x62) reserved ? ? ? ? ? ? ? ? (0x61) clkpr clkpce ? ? ? clkps3 clkps2 clkps1 clkps0 41 305 2513k?avr?07/09 atmega162/v (0x60) reserved ? ? ? ? ? ? ? ? 0x3f (0x5f) sreg i t h s v n z c 10 0x3e (0x5e) sph sp15 sp14 sp13 sp12 sp11 sp10 sp9 sp8 13 0x3d (0x5d) spl sp7 sp6 sp5 sp4 sp3 sp2 sp1 sp0 13 0x3c (2) (0x5c) (2) ubrr1h ursel1 ubrr1[11:8] 190 ucsr1c ursel1 umsel1 upm11 upm 10 usbs1 ucsz11 ucsz10 ucpol1 189 0x3b (0x5b) gicr int1 int0 int2 pcie1 pcie0 ? ivsel ivce 61 , 86 0x3a (0x5a) gifr intf1 intf0 intf2 pcif1 pcif0 ? ? ? 87 0x39 (0x59) timsk toie1 ocie1a ocie1b ocie2 ticie1 toie2 toie0 ocie0 102 , 134 , 154 0x38 (0x58) tifr tov1 ocf1a o cf1b ocf2 icf1 tov2 tov0 ocf0 103 , 135 , 155 0x37 (0x57) spmcr spmie rwwsb ? rwwsre blbset pgwrt pgers spmen 221 0x36 (0x56) emcucr sm0 srl2 srl1 srl0 srw01 srw00 srw11 isc2 30 , 44 , 85 0x35 (0x55) mcucr sre srw10 se sm1 isc11 isc10 isc01 isc00 30 , 43 , 84 0x34 (0x54) mcucsr jtd ? sm2 jtrf wdrf borf extrf porf 43 , 51 , 207 0x33 (0x53) tccr0 foc0 wgm00 com01 com00 wgm01 cs02 cs01 cs00 100 0x32 (0x52) tcnt0 timer/counter0 (8 bits) 102 0x31 (0x51) ocr0 timer/counter0 output compare register 102 0x30 (0x50) sfior tsm xmbk xmm2 xmm1 xmm0 pud psr2 psr310 32 , 70 , 105 , 156 0x2f (0x4f) tccr1a com1a1 com1a0 com1b1 com1b0 foc1a foc1b wgm11 wgm10 128 0x2e (0x4e) tccr1b icnc1 ices1 ? wgm13 wgm12 cs12 cs11 cs10 131 0x2d (0x4d) tcnt1h timer/counter1 ? counter register high byte 133 0x2c (0x4c) tcnt1l timer/counter1 ? counter register low byte 133 0x2b (0x4b) ocr1ah timer/counter1 ? output compare register a high byte 133 0x2a (0x4a) ocr1al timer/counter1 ? output compare register a low byte 133 0x29 (0x49) ocr1bh timer/counter1 ? output compare register b high byte 133 0x28 (0x48) ocr1bl timer/counter1 ? output compare register b low byte 133 0x27 (0x47) tccr2 foc2 wgm20 com21 com20 wgm21 cs22 cs21 cs20 149 0x26 (0x46) assr ? ? ? ? as2 tcn2ub ocr2ub tcr2ub 152 0x25 (0x45) icr1h timer/counter1 ? input capture register high byte 134 0x24 (0x44) icr1l timer/counter1 ? input capture register low byte 134 0x23 (0x43) tcnt2 timer/counter2 (8 bits) 151 0x22 (0x42) ocr2 timer/counter2 output compare register 151 0x21 (0x41) wdtcr ? ? ? wdce wde wdp2 wdp1 wdp0 53 0x20 (2) (0x40) (2) ubrr0h ursel0 ? ? ? ubrr0[11:8] 190 ucsr0c ursel0 umsel0 upm01 upm 00 usbs0 ucsz01 ucsz00 ucpol0 189 0x1f (0x3f) eearh ? ? ? ? ? ? ?eear8 20 0x1e (0x3e) eearl eeprom address register low byte 20 0x1d (0x3d) eedr eeprom data register 21 0x1c (0x3c) eecr ? ? ? ? eerie eemwe eewe eere 21 0x1b (0x3b) porta porta7 porta6 porta5 porta4 porta3 porta2 porta1 porta0 82 0x1a (0x3a) ddra dda7 dda6 dda5 dda4 dda3 dda2 dda1 dda0 82 0x19 (0x39) pina pina7 pina6 pina5 pina4 pina3 pina2 pina1 pina0 82 0x18 (0x38) portb portb7 portb6 portb 5 portb4 portb3 portb2 portb1 portb0 82 0x17 (0x37) ddrb ddb7 ddb6 ddb5 ddb4 ddb3 ddb2 ddb1 ddb0 82 0x16 (0x36) pinb pinb7 pinb6 pinb5 pinb4 pinb3 pinb2 pinb1 pinb0 82 0x15 (0x35) portc portc7 portc6 portc 5 portc4 portc3 portc2 portc1 portc0 82 0x14 (0x34) ddrc ddc7 ddc6 ddc5 ddc4 ddc3 ddc2 ddc1 ddc0 82 0x13 (0x33) pinc pinc7 pinc6 pi nc5 pinc4 pinc3 pinc2 pinc1 pinc0 83 0x12 (0x32) portd portd7 portd6 portd 5 portd4 portd3 portd2 portd1 portd0 83 0x11 (0x31) ddrd ddd7 ddd6 ddd5 ddd4 ddd3 ddd2 ddd1 ddd0 83 0x10 (0x30) pind pind7 pind6 pi nd5 pind4 pind3 pind2 pind1 pind0 83 0x0f (0x2f) spdr spi data register 164 0x0e (0x2e) spsr spif wcol ? ? ? ? ?spi2x 164 0x0d (0x2d) spcr spie spe dord mstr cpol cpha spr1 spr0 162 0x0c (0x2c) udr0 usart0 i/o data register 186 0x0b (0x2b) ucsr0a rxc0 txc0 udre0 fe0 dor0 upe0 u2x0 mpcm0 186 0x0a (0x2a) ucsr0b rxcie0 txcie0 udrie0 rxen0 txen0 ucsz02 rxb80 txb80 187 0x09 (0x29) ubrr0l usart0 baud rate register low byte 190 0x08 (0x28) acsr acd acbg aco aci acie acic acis1 acis0 195 0x07 (0x27) porte ? ? ? ? ? porte2 porte1 porte0 83 0x06 (0x26) ddre ? ? ? ? ? dde2 dde1 dde0 83 0x05 (0x25) pine ? ? ? ? ? pine2 pine1 pine0 83 0x04 (1) (0x24) (1) osccal ? cal6 cal5 cal4 cal3 cal2 cal1 cal0 39 ocdr on-chip debug register 202 0x03 (0x23) udr1 usart1 i/o data register 186 0x02 (0x22) ucsr1a rxc1 txc1 udre1 fe1 dor1 upe1 u2x1 mpcm1 186 address name bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 page 306 2513k?avr?07/09 atmega162/v notes: 1. when the ocden fuse is unprogrammed, the osccal regist er is always accessed on this address. refer to the debug- ger specific documentation for details on how to use the ocdr register. 2. refer to the usart description for details on how to access ubrrh and ucsrc. 3. for compatibility with future devices, reserved bits should be written to zero if accessed. reserved i/o memory addresses should never be written. 4. some of the status flags are cleared by writing a logical one to them. note that the cbi and sbi instructions will operate on all bits in the i/o register, writing a one back into any flag read as set, thus clearing the flag. the cbi and sbi instruction s work with registers 0x00 to 0x1f only. 0x01 (0x21) ucsr1b rxcie1 txcie1 udrie1 rxen1 txen1 ucsz12 rxb81 txb81 187 0x00 (0x20) ubrr1l usart1 baud rate register low byte 190 address name bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 page 307 2513k?avr?07/09 atmega162/v instruction set summary mnemonics operands description operation flags #clocks arithmetic and logic instructions add rd, rr add two registers rd rd + rr z,c,n,v,h 1 adc rd, rr add with carry two registers rd rd + rr + c z,c,n,v,h 1 adiw rdl,k add immediate to word rdh:rdl rdh:rdl + k z,c,n,v,s 2 sub rd, rr subtract two registers rd rd - rr z,c,n,v,h 1 subi rd, k subtract constant from register rd rd - k z,c,n,v,h 1 sbc rd, rr subtract with carry two registers rd rd - rr - c z,c,n,v,h 1 sbci rd, k subtract with carry constant from reg. rd rd - k - c z,c,n,v,h 1 sbiw rdl,k subtract immediate from word rdh:rdl rdh:rdl - k z,c,n,v,s 2 and rd, rr logical and registers rd rd ? rr z,n,v 1 andi rd, k logical and register and constant rd rd ? k z,n,v 1 or rd, rr logical or registers rd rd v rr z,n,v 1 ori rd, k logical or register and constant rd rd v k z,n,v 1 eor rd, rr exclusive or registers rd rd rr z,n,v 1 com rd one?s complement rd 0xff ? rd z,c,n,v 1 neg rd two?s complement rd 0x00 ? rd z,c,n,v,h 1 sbr rd,k set bit(s) in register rd rd v k z,n,v 1 cbr rd,k clear bit(s) in register rd rd ? (0xff - k) z,n,v 1 inc rd increment rd rd + 1 z,n,v 1 dec rd decrement rd rd ? 1 z,n,v 1 tst rd test for zero or minus rd rd ? rd z,n,v 1 clr rd clear register rd rd rd z,n,v 1 ser rd set register rd 0xff none 1 mul rd, rr multiply unsigned r1:r0 rd x rr z,c 2 muls rd, rr multiply signed r1:r0 rd x rr z,c 2 mulsu rd, rr multiply signed with unsigned r1:r0 rd x rr z,c 2 fmul rd, rr fractional multiply unsigned r1:r0 (rd x rr) << 1 z,c 2 fmuls rd, rr fractional multiply signed r1:r0 (rd x rr) << 1 z,c 2 fmulsu rd, rr fractional multiply signed with unsigned r1:r0 (rd x rr) << 1 z,c 2 branch instructions rjmp k relative jump pc pc + k + 1 none 2 ijmp indirect jump to (z) pc z none 2 jmp k direct jump pc knone3 rcall k relative subroutine call pc pc + k + 1 none 3 icall indirect call to (z) pc znone3 call k direct subroutine call pc knone4 ret subroutine return pc stack none 4 reti interrupt return pc stack i 4 cpse rd,rr compare, skip if equal if (rd = rr) pc pc + 2 or 3 none 1/2/3 cp rd,rr compare rd ? rr z, n,v,c,h 1 cpc rd,rr compare with carry rd ? rr ? c z, n,v,c,h 1 cpi rd,k compare register with immediate rd ? k z, n,v,c,h 1 sbrc rr, b skip if bit in register cleared if (rr(b)=0) pc pc + 2 or 3 none 1/2/3 sbrs rr, b skip if bit in register is set if (rr(b)=1) pc pc + 2 or 3 none 1/2/3 sbic p, b skip if bit in i/o register cleared if (p(b)=0) pc pc + 2 or 3 none 1/2/3 sbis p, b skip if bit in i/o register is set if (p(b)=1) pc pc + 2 or 3 none 1/2/3 brbs s, k branch if status flag set if (sreg(s) = 1) then pc pc+k + 1 none 1/2 brbc s, k branch if status flag cleared if (sreg(s) = 0) then pc pc+k + 1 none 1/2 breq k branch if equal if (z = 1) then pc pc + k + 1 none 1/2 brne k branch if not equal if (z = 0) then pc pc + k + 1 none 1/2 brcs k branch if carry set if (c = 1) then pc pc + k + 1 none 1/2 brcc k branch if carry cleared if (c = 0) then pc pc + k + 1 none 1/2 brsh k branch if same or higher if (c = 0) then pc pc + k + 1 none 1/2 brlo k branch if lower if (c = 1) then pc pc + k + 1 none 1/2 brmi k branch if minus if (n = 1) then pc pc + k + 1 none 1/2 brpl k branch if plus if (n = 0) then pc pc + k + 1 none 1/2 brge k branch if greater or equal, signed if (n v= 0) then pc pc + k + 1 none 1/2 brlt k branch if less than zero, signed if (n v= 1) then pc pc + k + 1 none 1/2 brhs k branch if half carry flag set if (h = 1) then pc pc + k + 1 none 1/2 brhc k branch if half carry flag cleared if (h = 0) then pc pc + k + 1 none 1/2 brts k branch if t flag set if (t = 1) then pc pc + k + 1 none 1/2 brtc k branch if t flag cleared if (t = 0) then pc pc + k + 1 none 1/2 brvs k branch if overflow flag is set if (v = 1) then pc pc + k + 1 none 1/2 brvc k branch if overflow flag is cleared if (v = 0) then pc pc + k + 1 none 1/2 308 2513k?avr?07/09 atmega162/v brie k branch if interrupt enabled if ( i = 1) then pc pc + k + 1 none 1/2 brid k branch if interrupt disabled if ( i = 0) then pc pc + k + 1 none 1/2 data transfer instructions mov rd, rr move between registers rd rr none 1 movw rd, rr copy register word rd+1:rd rr+1:rr none 1 ldi rd, k load immediate rd knone1 ld rd, x load indirect rd (x) none 2 ld rd, x+ load indirect and post-inc. rd (x), x x + 1 none 2 ld rd, - x load indirect and pre-dec. x x - 1, rd (x) none 2 ld rd, y load indirect rd (y) none 2 ld rd, y+ load indirect and post-inc. rd (y), y y + 1 none 2 ld rd, - y load indirect and pre-dec. y y - 1, rd (y) none 2 ldd rd,y+q load indirect with displacement rd (y + q) none 2 ld rd, z load indirect rd (z) none 2 ld rd, z+ load indirect and post-inc. rd (z), z z+1 none 2 ld rd, -z load indirect and pre-dec. z z - 1, rd (z) none 2 ldd rd, z+q load indirect with displacement rd (z + q) none 2 lds rd, k load direct from sram rd (k) none 2 st x, rr store indirect (x) rr none 2 st x+, rr store indirect and post-inc. (x) rr, x x + 1 none 2 st - x, rr store indirect and pre-dec. x x - 1, (x) rr none 2 st y, rr store indirect (y) rr none 2 st y+, rr store indirect and post-inc. (y) rr, y y + 1 none 2 st - y, rr store indirect and pre-dec. y y - 1, (y) rr none 2 std y+q,rr store indirect with displacement (y + q) rr none 2 st z, rr store indirect (z) rr none 2 st z+, rr store indirect and post-inc. (z) rr, z z + 1 none 2 st -z, rr store indirect and pre-dec. z z - 1, (z) rr none 2 std z+q,rr store indirect with displacement (z + q) rr none 2 sts k, rr store direct to sram (k) rr none 2 lpm load program memory r0 (z) none 3 lpm rd, z load program memory rd (z) none 3 lpm rd, z+ load program memory and post-inc rd (z), z z+1 none 3 spm store program memory (z) r1:r0 none - in rd, p in port rd pnone1 out p, rr out port p rr none 1 push rr push register on stack stack rr none 2 pop rd pop register from stack rd stack none 2 bit and bit-test instructions sbi p,b set bit in i/o register i/o(p,b) 1none2 cbi p,b clear bit in i/o register i/o(p,b) 0none2 lsl rd logical shift left rd(n+1) rd(n), rd(0) 0 z,c,n,v 1 lsr rd logical shift right rd(n) rd(n+1), rd(7) 0 z,c,n,v 1 rol rd rotate left through carry rd(0) c,rd(n+1) rd(n),c rd(7) z,c,n,v 1 ror rd rotate right through carry rd(7) c,rd(n) rd(n+1),c rd(0) z,c,n,v 1 asr rd arithmetic shift right rd(n) rd(n+1), n=0..6 z,c,n,v 1 swap rd swap nibbles rd(3..0) rd(7..4),rd(7..4) rd(3..0) none 1 bset s flag set sreg(s) 1 sreg(s) 1 bclr s flag clear sreg(s) 0 sreg(s) 1 bst rr, b bit store from register to t t rr(b) t 1 bld rd, b bit load from t to register rd(b) tnone1 sec set carry c 1c1 clc clear carry c 0 c 1 sen set negative flag n 1n1 cln clear negative flag n 0 n 1 sez set zero flag z 1z1 clz clear ze ro flag z 0 z 1 sei global interrupt enable i 1i1 cli global interrupt disable i 0 i 1 ses set signed test flag s 1s1 cls clear signed test flag s 0 s 1 sev set twos complement overflow. v 1v1 clv clear twos complement overflow v 0 v 1 set set t in sreg t 1t1 clt clear t in sreg t 0 t 1 seh set half carry flag in sreg h 1h1 mnemonics operands description operation flags #clocks 309 2513k?avr?07/09 atmega162/v clh clear half carry flag in sreg h 0 h 1 mcu control instructions nop no operation none 1 sleep sleep (see specific descr. for sleep function) none 1 wdr watchdog reset (see specific descr. for wdr/timer) none 1 break break for on-chip debug only none n/a mnemonics operands description operation flags #clocks 310 2513k?avr?07/09 atmega162/v ordering information notes: 1. this device can also be supplied in wafer form. please contact your local atmel sales office for detailed ordering info rmation and minimum quantities. 2. pb-free packaging alternative, complies to the european dire ctive for restriction of hazardous substances (rohs direc- tive).also halide free and fully green. 3. see figure 113 on page 266 . 4. see figure 114 on page 266 . speed (mhz) power supply ordering code package (1) operation range 8 (3) 1.8 - 5.5v atmega162v-8ai atmega162v-8pi atmega162v-8mi atmega162v-8au (2) atmega162v-8pu (2) atmega162v-8mu (2) 44a 40p6 44m1 44a 40p6 44m1 industrial (-4 0 c to 85 c) 16 (4) 2.7 - 5.5v atmega162-16ai atmega162-16pi atmega162-16mi atmega162-16au (2) atmega162-16pu (2) atmega162-16mu (2) 44a 40p6 44m1 44a 40p6 44m1 industrial (-4 0 c to 85 c) package type 44a 44-lead, thin (1.0 mm) plastic gull wing quad flat package (tqfp) 40p6 40-pin, 0.600? wide, plastic dual inline package (pdip) 44m1 44-pad, 7 x 7 x 1.0 mm body, lead pitch 0.50 mm, micro lead frame package (qfn/mlf) 311 2513k?avr?07/09 atmega162/v packaging information 44a 2325 orchard parkway san jose, ca 95131 title drawing no. r rev. 44a, 44-lead, 10 x 10 mm body size, 1.0 mm body thickness, 0.8 mm lead pitch, thin profile plastic quad flat package (tqfp) b 44a 10/5/2001 pin 1 identifier 0?~7? pin 1 l c a1 a2 a d1 d e e1 e b common dimensions (unit of measure = mm) symbol min nom max note notes: 1. this package conforms to jedec reference ms-026, variation acb. 2. dimensions d1 and e1 do not include mold protrusion. allowable protrusion is 0.25 mm per side. dimensions d1 and e1 are maximum plastic body size dimensions including mold mismatch. 3. lead coplanarity is 0.10 mm maximum. a 1.20 a1 0.05 0.15 a2 0.95 1.00 1.05 d 11.75 12.00 12.25 d1 9.90 10.00 10.10 note 2 e 11.75 12.00 12.25 e1 9.90 10.00 10.10 note 2 b 0.30 0.45 c 0.09 0.20 l 0.45 0.75 e 0.80 typ 312 2513k?avr?07/09 atmega162/v 40p6 2325 orchard parkway san jose, ca 95131 title drawing no. r rev. 40p6 , 40-lead (0.600"/15.24 mm wide) plastic dual inline package (pdip) b 40p6 09/28/01 pin 1 e1 a1 b ref e b1 c l seating plane a 0?~ 15? d e eb common dimensions (unit of measure = mm) symbol min nom max note a 4.826 a1 0.381 d 52.070 52.578 note 2 e 15.240 15.875 e1 13.462 13.970 note 2 b 0.356 0.559 b1 1.041 1.651 l 3.048 3.556 c 0.203 0.381 eb 15.494 17.526 e 2.540 typ notes: 1. this package conforms to jedec reference ms-011, variation ac. 2. dimensions d and e1 do not include mold flash or protrusion. mold flash or protrusion shall not exceed 0.25 mm (0.010"). 313 2513k?avr?07/09 atmega162/v 44m1 title drawing no. gpc rev. packa g e drawin g contact: p a ck a gedr a wing s @ a tmel.com 44m1 zw s h 44m1, 44-pad, 7 x 7 x 1.0 mm body, lead pitch 0.50 mm, 5.20 mm exposed pad, thermally enhanced plastic very thin quad flat no lead package (vqfn) 9/26/0 8 common dimen s ion s (unit of me asu re = mm) s ymbol min nom max note a 0. 8 0 0.90 1.00 a1 ? 0.02 0.05 a 3 0.20 ref b 0.1 8 0.2 3 0. 3 0 d d2 5.00 5.20 5.40 6.90 7.00 7.10 6.90 7.00 7.10 e e2 5.00 5.20 5.40 e 0.50 b s c l 0.59 0.64 0.69 k 0.20 0.26 0.41 note: jedec s t a nd a rd mo-220, fig. 1 ( s aw s ing u l a tion) vkkd- 3 . top view s ide view bottom view d e m a rked pin# 1 id e2 d2 b e pin #1 corner l a1 a 3 a s eating plane pin #1 tr i a ngle pin #1 ch a mfer (c 0. 3 0) option a option b pin #1 notch (0.20 r) option c k k 1 2 3 314 2513k?avr?07/09 atmega162/v errata the revision letter in this section refers to the revision of the atmega162 device. atmega162, all rev. there are no errata for this revision of atmega162. however, a proposal for solving problems regarding the jtag instruction idcode is presented below. ? idcode masks data from tdi input ? reading eeprom by using st or sts to set eer e bit triggers unexp ected interr upt request ? interrupts may be lost when writing th e timer register in asynchronous timer 1. idcode masks data from tdi input the public but optional jtag in struction idcode is not implemented correctly according to ieee1149.1; a logic one is scanned into the shift register instead of the tdi input while shift- ing the device id register. hence, captured data from the preceding devices in the boundary scan chain are lost and replaced by all-ones, and data to succeeding devices are replaced by all-ones during update-dr. if atmega162 is the only device in the scan chain, the problem is not visible. problem fix / workaround select the device id register of the atmeg a162 (either by issuing the idcode instruction or by entering the test-logic-reset state of the tap controller) to read out the contents of its device id register and possibly data from succeeding devices of the scan chain. note that data to succeeding devices cannot be entered during this scan, but data to preceding devices can. iss ue the bypass instruction to the atmeg a162 to select its bypass register while reading the device id registers of preceding devices of the boundary scan chain. never read data from succeeding devices in the boundary scan chain or upload data to the succeeding devices while the device id register is selected for the atmega162. note that the idcode instruction is the default instruction selected by the test-logic-reset state of the tap-controller. alternative problem fix / workaround if the device ids of all devices in the bounda ry scan chain must be captured simultaneously (for instance if blind interrogation is used), the boundary scan chain can be connected in such way that the atmega162 is the first devi ce in the chain. update-dr will still not work for the succeeding devices in the boundary scan chain as long as idcode is present in the jtag instruction register, but the device id registered cannot be uploaded in any case. 2. reading eeprom by using st or sts to set eere bit triggers unexpected interrupt request. reading eeprom by using the st or sts command to set th e eere bit in the eecr reg- ister triggers an unexpecte d eeprom interrupt request. problem fix / workaround always use out or sbi to set eere in eecr. 3. interrupts may be lost when writing the timer register in asynchronous timer the interrupt will be lo st if a timer register that is synchr onous timer clock is written when the asynchronous timer/counter register (tcntx) is 0x00. problem fix / workaround always check that the asynchronous timer/counter register neither have the value 0xff nor 0x00 before writing to the asynchronous timer control register (tccrx), asynchronous timer counter register (tcntx), or asynchronous output compare register (ocrx). 315 2513k?avr?07/09 atmega162/v datasheet revision history please note that the referring page numbers in th is section are referred to this document. the referring revision in this section are referring to the document revision. changes from rev. 2513j-08/07 to rev. 2513k-07/09 1. updated ?errata? on page 314 . 2. updated the last page with atmel?s new adresses. changes from rev. 2513i-04/07 to rev. 2513j-08/07 1. updated ?features? on page 1 . 2. added ?data retention? on page 7 . 3. updated ?errata? on page 314 . 4. updated ?version? on page 205 . 5. updated ?c code example (1) ? on page 172 . 6. updated figure 18 on page 35 . 7. updated ?clock distribution? on page 35 . 8. updated ?spi serial programming algorithm? on page 246 . 9. updated ?slave mode? on page 162 . changes from rev. 2513h-04/06 to rev. 2513i-04/07 1. updated ?using all 64kb locations of external memory? on page 34 . 2. updated ?bit 6 ? acbg: analog comparator bandgap select? on page 195 . 3. updated v oh conditions in ?dc characteristics? on page 264 . changes from rev. 2513g-03/05 to rev. 2513h-04/06 1. added ?resources? on page 7 . 2. updated ?calibrated internal rc oscillator? on page 38 . 3. updated note for table 19 on page 50 . 4. updated ?serial peripheral interface ? spi? on page 157 . changes from rev. 2513f-09/03 to rev. 2513g-03/05 1. mlf-package alternative changed to ?quad flat no-lead/micro lead frame package qfn/mlf?. 2. updated ?electrical characteristics? on page 264 3. updated ?ordering information? on page 310 changes from rev. 2513d-04/03 to rev. 2513e-09/03 1. removed ?preliminary? from the datasheet. 2. added note on figure 1 on page 2 . 316 2513k?avr?07/09 atmega162/v 3. renamed and updated ?on-chip debug system? to ?jtag interface and on-chip debug system? on page 46 . 4. updated table 18 on page 48 and table 19 on page 50 . 5. updated ?test access port ? tap? on page 197 regarding jtagen. 6. updated description for the jtd bit on page 207 . 7. added note on jtagen in table 99 on page 233 . 8. updated absolute maximum ratings* and dc characteristics in ?electrical character- istics? on page 264 . 9. added a proposal for solving problems regarding the jtag instruction idcode in ?errata? on page 314 . changes from rev. 2513c-09/02 to rev. 2513d-04/03 1. updated the ?ordering information? on page 310 and ?packaging information? on page 311 . 2. updated ?features? on page 1 . 3. added characterization plots under ?atmega162 typical characteristics? on page 275 . 4. added chip erase as a first step under ?programming the flash? on page 260 and ?programming the eeprom? on page 262 . 5. changed cal7, the highest bit in the osccal register, to a reserved bit on page 39 and in ?register summary? on page 304 . 6. changed cpce to clkpce on page 41 . 7. corrected code examples on page 55 . 8. corrected ocn waveforms in figure 52 on page 120 . 9. various minor timer1 corrections. 10. added note under ?filling the temporary buffer (page loading)? on page 224 about writing to the eeprom during an spm page load. 11. added section ?eeprom write during power-down sleep mode? on page 24 . 12. added information about pwm symmetry for timer0 on page 98 and timer2 on page 147 . 13. updated table 18 on page 48 , table 20 on page 50 , table 36 on page 77 , table 83 on page 205 , table 109 on page 247 , table 112 on page 267 , and table 113 on page 268 . 14. added figures for ?absolute maximum frequency as a function of vcc, atmega162? on page 266 . 317 2513k?avr?07/09 atmega162/v 15. updated figure 29 on page 64 , figure 32 on page 68 , and figure 88 on page 210 . 16. removed table 114, ?external rc oscillator, typical frequencies (1) ,? on page 265. 17. updated ?electrical characteristics? on page 264 . changes from rev. 2513b-09/02 to rev. 2513c-09/02 1. changed the endurance on the flash to 10,000 write/erase cycles. changes from rev. 2513a-05/02 to rev. 2513b-09/02 1. added information for atmega162u. information about atmega162u included in ?features? on page 1 , table 19, ?bodlevel fuse coding,? on page 50 , and ?ordering information? on page 310 . 318 2513k?avr?07/09 atmega162/v i 2513k?avr?07/09 atmega162/v table of contents features 1 pin configurations 2 disclaimer 2 overview 3 block diagram 3 atmega161 and atmega162 compatibility 4 pin descriptions 5 resources 7 data retention 7 about code examples 8 avr cpu core 9 introduction 9 architectural overview 9 alu ? arithmetic logic unit 10 status register 10 general purpose register file 12 stack pointer 13 instruction execution timing 14 reset and interrupt handling 14 avr atmega162 memories 17 in-system reprogrammable flash program memory 17 sram data memory 18 eeprom data memory 19 i/o memory 25 external memory interface 26 xmem register description 30 ii 2513k?avr?07/09 atmega162/v system clock and clock options 35 clock systems and their distribution 35 clock sources 36 default clock source 36 crystal oscillator 36 low-frequency crys tal oscillator 38 calibrated internal rc oscillator 38 external clock 40 clock output buffer 40 timer/counter oscillator 41 system clock prescaler 41 power management and sleep modes 43 idle mode 44 power-down mode 44 power-save mode 45 standby mode 45 extended standby mode 45 minimizing power consumption 46 system control and reset 47 internal voltage reference 52 watchdog timer 52 timed sequences for changing the configuration of the watchdog timer 56 interrupts 57 interrupt vectors in atmega162 57 i/o-ports 63 introduction 63 ports as genera l digital i/o 63 alternate port functions 68 register description for i/o-ports 82 external interrupts 84 8-bit timer/counter0 with pwm 89 overview 89 timer/counter clock sources 90 counter unit 91 output compare unit 91 compare match output unit 93 modes of operation 94 timer/counter timing diagrams 98 8-bit timer/counter register description 100 iii 2513k?avr?07/09 atmega162/v timer/counter0, timer/counter1, and timer/counter3 prescalers 104 16-bit timer/counter (timer/c ounter1 and timer/counter3) 106 restriction in atmega161 compatibility mode 106 overview 106 accessing 16-bit registers 109 timer/counter clock sources 112 counter unit 112 input capture unit 113 output compare units 114 compare match output unit 117 modes of operation 118 timer/counter timing diagrams 126 16-bit timer/counter re gister description 128 8-bit timer/counter2 with pwm and asynchr onous operation 138 overview 138 timer/counter clock sources 139 counter unit 140 output compare unit 140 compare match output unit 142 modes of operation 143 timer/counter timing diagrams 147 8-bit timer/counter register description 149 asynchronous operation of the timer/counter 152 timer/counter prescaler 156 serial peripheral interface ? spi 157 ss pin functionality 162 data modes 165 usart 166 dual usart 166 clock generation 168 frame formats 171 usart initialization 172 data transmission ? the usart transmitter 173 data reception ? the usart receiver 175 asynchronous data reception 179 multi-processor communication mode 182 accessing ubrrh/ ucsrc registers 184 usart register description 186 examples of baud rate setting 191 iv 2513k?avr?07/09 atmega162/v analog comparator 195 jtag interface and on- chip debug system 197 features 197 overview 197 test access port ? tap 197 tap controller 200 using the boundary-scan chain 200 using the on-chip debug system 201 on-chip debug specific jtag instructions 202 on-chip debug related register in i/o memory 202 using the jtag progra mming capabilities 202 bibliography 203 ieee 1149.1 (jtag) boundary-scan 204 features 204 system overview 204 data registers 205 boundary-scan specific jtag instructions 206 boundary-scan chain 208 atmega162 boundary-scan order 213 boundary-scan description language files 216 boot loader support ? read-while -write self-programming 217 features 217 application and boot loader flash sections 217 read-while-write and no read-w hile-write flash sections 217 boot loader lock bits 219 entering the boot loader program 221 addressing the flash during self-programming 223 self-programming the flash 224 memory programming 231 program and data memory lock bits 231 fuse bits 232 signature bytes 234 calibration byte 234 parallel programming parameters, pin mapping, and commands 234 parallel programming 236 serial downloading 245 spi serial programming pin mapping 245 programming via the jtag interface 250 v 2513k?avr?07/09 atmega162/v electrical characteristics 264 absolute maximum ratings* 264 dc characteristics 264 external clock drive waveforms 267 external clock drive 267 spi timing characteristics 268 external data memory timing 270 atmega162 typical characteristics 275 register summary 304 instruction set summary 307 ordering information 310 packaging information 311 44a 311 40p6 312 44m1 313 errata 314 atmega162, all rev. 314 datasheet revision history 315 changes from rev. 2513i-04/07 to rev. 2513j-08/07 315 changes from rev. 2513h-04/06 to rev. 2513i-04/07 315 changes from rev. 2513g-03/05 to rev. 2513h-04/06 315 changes from rev. 2513f-09/03 to rev. 2513g-03/05 315 changes from rev. 2513d-04/03 to rev. 2513e-09/03 315 changes from rev. 2513c-09/02 to rev. 2513d-04/03 316 changes from rev. 2513b-09/02 to rev. 2513c-09/02 317 changes from rev. 2513a-05/02 to rev. 2513b-09/02 317 2513k?avr?07/09 headquarters international atmel corporation 2325 orchard parkway san jose, ca 95131 usa tel: 1(408) 441-0311 fax: 1(408) 487-2600 atmel asia unit 1-5 & 16, 19/f bea tower, millennium city 5 418 kwun tong road kwun tong, kowloon hong kong tel: (852) 2245-6100 fax: (852) 2722-1369 atmel europe le krebs 8, rue jean-pierre timbaud bp 309 78054 saint-quentin-en- yvelines cedex france tel: (33) 1-30-60-70-00 fax: (33) 1-30-60-71-11 atmel japan 9f, tonetsu shinkawa bldg. 1-24-8 shinkawa chuo-ku, tokyo 104-0033 japan tel: (81) 3-3523-3551 fax: (81) 3-3523-7581 product contact web site www.atmel.com technical support avr@atmel.com sales contact www.atmel.com/contacts literature requests www.atmel.com/literature disclaimer: the information in this document is provided in connection with atmel products. no license, express or implied, by estoppel or otherwise, to any intellectual property right is granted by this document or in connection with the sale of atmel products. except as set forth in atmel?s terms and condi- tions of sale located on atmel?s web site, atmel assumes no li ability whatsoever and disclaims any express, implied or statutor y warranty relating to its products including, but not limited to, the implied warranty of merchantability, fitness for a particu lar purpose, or non-infringement. in no event shall atmel be liable for any direct, indirect, consequential, punitive, special or i nciden- tal damages (including, without limitation, damages for loss of profits, business interruption, or loss of information) arising out of the use or inability to use this document, even if atme l has been advised of the possibility of such damages. atmel makes no representations or warranties with respect to the accuracy or comp leteness of the contents of this document and reserves the rig ht to make changes to specifications and product descriptions at any time without notice. atmel does not make any commitment to update the information contained her ein. unless specifically provided otherwise, atmel products are not suitable for, and shall not be used in, automotive applications. atmel?s products are not int ended, authorized, or warranted for use as components in applications in tended to support or sustain life. ? 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