AVR

Modified Harvard architecture 8-bit RISC microcontroller. Atmel's AVRs have a two-stage, single-level pipeline design.

There are the following registers:

• 32 general purpose 8-bit registers, r0-r31; with some alias like x=r27:r26, y=r29:28 and z=r31:r30
• pc 16- or 22-bit program counter
• sp 8- or 16-bit stack pointer
• sreg 8-bit status register
• rampx, rampy, rampz and eind

Usually r0 and r1 are fixed as usage.

Links

• Wikipedia's AVR Instruction set
• Instruction set manual
• Instruction set summary
• Branching
• AVR opcodes table by as
• Instructions encoding
• Table with opcode
• GCC-AVR Inline Assembler Cookbook
• A few remarks on the avr-gcc inline assembler