LCD應用控制 8051 assembly

	;------------------------------------------
	; ==================================
	; == lcd應用控制 ==
	; == 2014/12/29 ==
	; == 蘇偉諺 ==
	; ==================================
	;------------------------------------------
	;於lcd顯示第二列顯示'THIS IS 2ND LINE'並閃爍三次，然後由左而右依序清除
	;-----------------------------------------------------------------------------
	; parameter define
	;-----------------------------------------------------------------------------
	lcd_enable equ p3.7
	lcd_rs equ p2.1
	lcd_bus equ p0
	;-----------------------------------------------------------------------------
	; main program
	;-----------------------------------------------------------------------------
	org 00h
	mov sp,#5fh
	call initlcd
	mov r5,#3
	glint: call clrlcd;;;;;;;
	mov r7,#20
	call delay50ms
	mov a,#1
	mov b,#0
	call goxy
	mov dptr,#str
	call prtstring
	mov r7,#20
	call delay50ms
	djnz r5,glint
	mov r4,#16
	mov b,#15
	clrrr: mov a,#1
	call goxy
	mov a,#20h
	call wrdr
	mov r7,#20
	call delay50ms
	dec b
	djnz r4,clrrr
	jmp $
	str: db 'THIS IS 2ND LINE','$'
	;-----------------------------------------------------------------------------
	; go x line, y char
	;-----------------------------------------------------------------------------
	goxy: anl b,#00001111b
	cjne a,#1,chk1
	mov a,b
	add a,#10000000b;setb a.7 orl 10000000b
	call wrir
	ret
	chk1: mov a,b
	add a,#11000000b
	call wrir
	ret
	;-----------------------------------------------------------------------------
	; initial lcd
	;-----------------------------------------------------------------------------
	initlcd: mov a,#38h
	call wrir
	mov a,#0dh
	call wrir
	mov a,#06h
	call wrir
	clrlcd: mov a,#01h
	call wrir
	mov r7,#40;清除需延遲2ms
	call delay
	ret
	;-------------------------------------------------------------------------------
	; delay time=r7*0.05ms
	;-------------------------------------------------------------------------------
	delay: mov tmod,#00100001b
	dloop: mov th0,#high(65536-50)
	mov tl0,#low(65536-50)
	setb tr0
	jnb tf0,$
	clr tr0
	clr tf0
	djnz r7,dloop
	ret
	;-------------------------------------------------------------------------------
	; delay time=r7*50ms
	;-------------------------------------------------------------------------------
	delay50ms:
	dloop1: mov th0,#high(65536-50000)
	mov tl0,#low(65536-50000)
	setb tr0
	jnb tf0,$
	clr tr0
	clr tf0
	djnz r7,dloop1
	ret
	prtstring: push acc
	prtloop: clr a
	movc a,@a+dptr
	cjne a,#'$',next
	jmp endprt
	next: call wrdr
	inc dptr
	jmp prtloop
	endprt: pop acc
	ret
	;-----------------------------------------------------------------------------
	; write control word to instruction register
	;-----------------------------------------------------------------------------
	wrir: setb lcd_enable
	clr lcd_rs
	mov lcd_bus,a
	clr lcd_enable
	mov r7,#1
	call delay
	ret
	;-----------------------------------------------------------------------------
	; write data to data register
	;-----------------------------------------------------------------------------
	wrdr: setb lcd_enable
	setb lcd_rs
	mov lcd_bus,a
	clr lcd_enable
	mov r7,#1
	call delay
	ret
	end

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