	list      p=16f628
	#include <p16f628.inc>
	
	__CONFIG _CP_OFF & _WDT_OFF & _BODEN_ON & _PWRTE_ON & _INTRC_OSC_NOCLKOUT & _MCLRE_OFF & _LVP_OFF

	org 0x000

count1	equ	0x20
count2	equ	0x21

init
	bsf	STATUS, RP0
	movlw	0x00
	movwf	PORTA
	movwf	PORTB
	bcf	STATUS, RP0

loop
; PortB[0] = 1
	bsf	PORTB, 0

; wait for 0.3sec.
	clrf	count1
wait1a	clrf	count2
wait1b	nop
	decfsz	count2, F
	goto	wait1b
	decfsz	count1, F
	goto	wait1a

; PortB[0] = 0
	bcf	PORTB, 0

; wait for 0.3sec.
	clrf	count1
wait2a	clrf	count2
wait2b	nop
	decfsz	count2, F
	goto	wait2b
	decfsz	count1, F
	goto	wait2a

; repeat loop
	goto	loop

	end
