mirror of
https://github.com/hsoft/collapseos.git
synced 2024-12-26 16:28:06 +11:00
43 lines
835 B
NASM
43 lines
835 B
NASM
; REGISTER USAGE
|
|
;
|
|
; R1: overflow counter
|
|
; R16: tmp stuff
|
|
|
|
.inc "avr.h"
|
|
.inc "tn254585.h"
|
|
.inc "tn45.h"
|
|
|
|
main:
|
|
ldi r16, RAMEND&0xff
|
|
out SPL, r16
|
|
ldi r16, RAMEND}8
|
|
out SPH, r16
|
|
|
|
sbi DDRB, 0
|
|
cbi PORTB, 0
|
|
|
|
; To have a blinking delay that's visible, we have to prescale a lot.
|
|
; The maximum prescaler is 1024, which makes our TCNT0 increase
|
|
; 976 times per second, which means that it overflows 4 times per
|
|
; second.
|
|
in r16, TCCR0B
|
|
ori r16, 0x05 ; CS00 + CS02 = 1024 prescaler
|
|
out TCCR0B, r16
|
|
|
|
clr r1
|
|
|
|
loop:
|
|
in r16, TIFR ; TIFR0
|
|
sbrc r16, 1 ; is TOV0 flag clear?
|
|
rcall toggle
|
|
rjmp loop
|
|
|
|
toggle:
|
|
ldi r16, 0b00000010 ; TOV0
|
|
out TIFR, R16
|
|
inc r1
|
|
cbi PORTB, 0
|
|
sbrs r1, 1 ; if LED is on
|
|
sbi PORTB, 0
|
|
ret
|