;dc motor drive sub-program
;=======register define================
mr1		equ	p2.4
mr2		equ	p2.5
ml1		equ	p2.6
ml2		equ	p2.7
;
mtr_cnt0	equ	6fh
mtr_cnt1	equ	6eh
mtr_time	equ	6dh		;dc motor run time
;======================================
		org	00h
		clr	mr1		;initial status off
		clr	mr2		;initial status off
		clr	ml1		;initial status off
		clr	ml2		;initial status off
;
mtr_loop:
		mov	mtr_time,#20	;motor run time=2 Sec
		call	forward
;
		mov	mtr_time,#20	;motor run time=2 Sec
		call	stop
;
		mov	mtr_time,#20	;motor run time=2 Sec
		call	back
;
		mov	mtr_time,#20	;motor run time=2 Sec
		call	stop
;
		jmp	mtr_loop
;====================================================================
;-------------car forwarding-----------
forward:
		clr	mr1		;right must inverse
		setb	mr2
		setb	ml1		;left is correct
		clr	ml2
		call	run_dl
		ret
;------------car backing---------------
back:
		setb	mr1		;right must inverse
		clr	mr2
		clr	ml1		;left is correct
		setb	ml2
		call	run_dl
		ret
;------------car lefting---------------
left:
;------------car righting--------------
right:
;------------car stop------------------
stop:
		clr	mr1
		clr	mr2
		clr	ml1
		clr	ml2
		call	run_dl
		ret	
;------------car run time--------------
run_dl:
dl1:		mov	mtr_cnt0,#200	;about 100mS x mtr_time
dl2:		mov	mtr_cnt1,#250
		djnz	mtr_cnt1,$
		djnz	mtr_cnt0,dl2
		djnz	mtr_time,dl1
		ret
;
		end