Atmel AVR instruction set

Here is the basic Atmel AVR instruction set.

Arithmetic operations work on registers R0-R31 but not directly on RAM and take one clock cycle, except for multiplication and word-wide addition (ADIW and SBIW) which take two cycles.

RAM and I/O space can be accessed only by copying to or from registers. Indirect access (including optional postincrement, predecrement or constant displacement) is possible through registers X, Y, and Z. All accesses to RAM takes two clock cycles. Moving between registers and I/O is one cycle. Moving eight or sixteen bit data between registers or constant to register is also one cycle. Reading program memory (LPM) takes three cycles.

There are two types of conditional branches: jumps to address and skips. Conditional branches (BRxx) can test an ALU flag and jump to specified address. Skips (SBxx) test an arbitrary bit in a register or I/O and skip the next instruction if the test was true.

AVR instruction set

Arithmetic	Bit & Others	Transfer	Jump	Branch	Call
ADD Rd, Rr ADC Rd, Rr ADIW Rd+1:Rd, K6 SUB Rd, Rr SUBI Rd, K8 SBC Rd, Rr SBCI Rd, K8 SBIW Rd+1:Rd, K6 INC Rd DEC Rd AND Rd, Rr ANDI Rd, K8 OR Rd, Rr ORI Rd, K8 EOR Rd, Rr COM Rd NEG Rd CP Rd, Rr CPC Rd, Rr CPI Rd, K8 SWAP Rd LSR Rd ROR Rd ASR Rd MUL Rd, Rr MULS Rd, Rr MULSU Rd, Rr FMUL Rd, Rr FMULS Rd, Rr FMULSU Rd, Rr	BSET s BCLR s SBI A, b CBI A, b BST Rd, b BLD Rd, b NOP BREAK SLEEP WDR	MOV Rd, Rr MOVW Rd+1:Rd, Rr+1:Rr IN Rd, A OUT A, Rr PUSH Rr POP Rr LDI Rd, K8 LDS Rd, K16 LD Rd, X LD Rd, -X LD Rd, X+ LDD Rd, Y+K6 LD Rd, -Y LD Rd, Y+ LDD Rd, Z+K6 LD Rd, -Z LD Rd, Z+ STS K16, Rr ST X, Rr ST -X, Rr ST X+, Rr STD Y+K6, Rr ST -Y, Rr ST Y+, Rr STD Z+K6, Rr ST -Z, Rr ST Z+, Rr LPM LPM Rd, Z LPM Rd, Z+ ELPM ELPM Rd, Z ELPM Rd, Z+ SPM	RJMP K12 IJMP EIJMP JMP K22	CPSE Rd, Rr SBRC Rr, b SBRS Rr, b SBIC A, b SBIS A, b BRBC s, K7 BRBS s, K7	RCALL K12 ICALL EICALL CALL K22 RET RETI

Instruction set inheritance

Not all instructions are implemented in all AVR controllers. This is the case of the instructions performing multiplications, extended loads/jumps/calls, long jumps, and power control.

See also

* Atmel AVR

External links

* [http://users.rcn.com/rneswold/avr/ GNU Development Environment]
** [http://www.linuxfocus.org/English/November2004/article352.shtml Programming the AVR microcontroller with GCC] by Guido Socher
** [http://users.rcn.com/rneswold/avr/ A GNU Development Environment for the AVR Microcontroller] by Rich Neswold
** [http://gcc.gnu.org/onlinedocs/gcc-3.3.5/gcc/AVR-Options.html AVR Options] in GCC-AVR
* [http://www.atmel.com/dyn/resources/prod_documents/DOC0856.PDF Atmel AVR instruction set PDF(149 pages)]