m820250116extint.asm

; (C) David Vajda
; 2025-01-16
; AVR/Atmega8 LED, Extern Interrupt

.include "m8def.inc"

.org 0x000
rjmp RESET
.org INT0addr
rjmp ExtInt0
.org INT1addr
rjmp ExtInt1

RESET:
ldi r16, HIGH (RAMEND)
out SPH, r16
ldi r16, LOW (RAMEND)
out SPL, r16

ldi r16, 0xff
out DDRB, r16

ldi r16, 0x00
out DDRD, r16

ldi r16, 0xff
out PORTB, r16

ldi r16, (1 << INT1) | (1 << INT0)
out GICR, r16
ldi r16, (1 << ISC11) | (1 << ISC10) | (1 << ISC01) | (1 << ISC00)
out MCUCR, r16

sei

end: rjmp end

ExtInt0:
dec r16
out PORTB, r16
reti

ExtInt1:
inc r16
out PORTB, r16
reti