Basic template for getting started with bare metal GNU Assembler development on arduino uno
make build
make sure to update the port the arduino uno is attached to your system in the Makefile in that line:
PROGRAMMER = -v -patmega328p -carduino -P/dev/cu.usbmodem142201 -b115200 -D
Run:
make flash
make
Registers like PORTB, DDRB ... are mapped to the beginning of the memory the adresses can be found in the datasheet
main.s contains some example on accessing the PORTB to make the onboard pin blink
; register memory mapping (check datasheet)
.equiv PORTB, 0x05
.equiv DDRB, 0x04
.equiv PINB, 0x03
...
out PORTB,r16