#include 	"c:\miniide\hcs12.inc"
hi_time 	equ     	900
lo_time 	equ     	2100
		org     	$1500
		movb    	#$90,TSCR1      	; enable TCNT with fast timer flag clear
		movb    	#$03,TSCR2      	; disable TCNT interrupt, set prescaler to 8
		bset   	TIOS,OC0       	; enable OC0
		movb    	#$03,TCTL2      	; select pull high as pin action
		ldd     	TCNT            	; start an OC0 operation with 700 us as delay
repeat	addd    	#lo_time       	;       "
		std     	TC0             	;       "
low		brclr   	TFLG1,C0F,low   	; wait until OC0 pin go high
		movb    	#$02,TCTL2      	; select pull low as pin action
		ldd     	TC0             	; start an OC operation with 300 us as delay
		addd    	#hi_time       	;       "
		std     	TC0             	;       "
high    	brclr  	TFLG1,C0F,high  	; wait until OC0 pin go low
		movb    	#$03,TCTL2      	; select pull high as pin action
		ldd     	TC0
		bra     	repeat
		end