AVR Assembler is the lowest level of human-readable code for Atmel (now Microchip) AVR microcontrollers—the brains inside Arduino Uno (ATmega328P), Nano, and many custom boards. While most people use Arduino's C++ environment, learning Assembly gives you absolute control over every clock cycle, every register, and every byte of memory.
DELAY: ; Delay loop (approximate) ldi r17, 0xFF L1: ldi r18, 0xFF L2: dec r18 brne L2 dec r17 brne L1 dec r16 brne DELAY ret avr assembler download
So, you want to blink an LED by talking directly to the metal? Welcome. AVR Assembler is the lowest level of human-readable
Now assemble it using GNU toolchain:
Now go download. Make that LED blink in pure Assembly. You'll never look at digitalWrite() the same way again. Last updated: 2025. Toolchain versions change, but the GNU assembler for AVR has been stable for 15+ years. If a link is dead, search for "avr-gcc" on your OS's package manager. Welcome
LOOP: ; Turn LED on sbi PORTB, 5 ldi r16, 0xFF call DELAY ; Turn LED off cbi PORTB, 5 ldi r16, 0xFF call DELAY rjmp LOOP
RESET: ; Set PB5 as output sbi DDRB, 5