.include "8535def.inc"
.org $0000
 rjmp main
.org $0006
 rjmp tim1_compa
main:    ldi r16,low(ramend)   ;棧指針置初值
         out spl,r16
         ldi r16,high(ramend)
         out sph,r16
         ldi r16,$01           ;PC0口定義為輸出口
         out ddrc,r16          
         ldi r16,$10           ;允許T1比較匹配A中斷
         out timsk,r16
         clr r16               ;置TCNT1初值為0
         out tcnt1l,r16
         out tcnt1h,r16
         ldi r16,$7a           ;ocr1a置$7a12,即1秒中斷一次
         out ocr1ah,r16
         ldi r16,$12
         out ocr1al,r16
         ldi r16,$0c           ;T/C1對主頻256分頻定時
         out tccr1b,r16         
         sei
here:    rjmp here
tim1_compa:
        in r1,sreg             ;保護標志
        in r2,portc            ;PC口取反
        com r2
        out portc,r2        
        out sreg,r1            ;恢復標志
        reti