.INCLUDE "tn13def.inc"

; data direction = output
	sbi DDRB, 1 ; PB1

loop:

; clear bit
	cbi PORTB, 1

; wait
loop1:
 	sbiw ZL, 1
	brne loop1

; set bit
	sbi PORTB, 1

; wait
loop2:
	sbiw ZL, 1
	brne loop2

; again! again! again!
	rjmp loop