s19-4.asm

手把手教你学单片机实验程序

;********89C51引脚定义********
	RS BIT P3.3
	R_W BIT P3.4
	E BIT P3.5
	DB0_DB7 EQU P1
;*******程序开始******
	ORG 0000H
	LJMP MAIN
	ORG 030H
MAIN:	MOV SP,#60H
	LCALL INITIAL
	LCALL CLS
	MOV R4,#8
	LCALL SAVE_CGRAM
	MOV A,#11000000B
	LCALL WRITE_COM
	MOV A,#00H
	LCALL WRITE_DATA
	SJMP $
;****** 启动LCM子程序******
INITIAL:MOV A,#00111000B
	LCALL WRITE_COM
	MOV A,#00001100B 
	LCALL WRITE_COM 
	MOV A,#00000110B 
	LCALL WRITE_COM 
	RET
;******查询忙碌标志信号子程序******
CHECK_BUSY: 	PUSH ACC
BUSY_LOOP:	CLR E
	SETB R_W
	CLR RS
	SETB E
	MOV A, DB0_DB7
	CLR E
	JB ACC.7,BUSY_LOOP
	POP ACC
	LCALL DEL
	RET
;****** 写指令到LCM子程序******
WRITE_COM: 	LCALL CHECK_BUSY
	CLR E
	CLR RS 
	CLR R_W
	SETB E
	MOV DB0_DB7,A
	CLR E
	RET
;****** 写数据到LCM子程序******
WRITE_DATA: 	LCALL CHECK_BUSY
	CLR E
	SETB RS 
	CLR R_W
	SETB E
	MOV  DB0_DB7,A
	CLR E
	RET
;*******清除LCM子程序*******
CLS:	MOV A,#00000001B
	LCALL WRITE_COM
	RET
;****延时2.7mS子程序****
DEL:	MOV R6,#5
L1:	MOV R7,#248
	DJNZ R7,$
	DJNZ R6,L1
	RET
;*******自定义图形写入CGRAM子程序********
SAVE_CGRAM:	MOV A,#01000000B
	LCALL WRITE_COM
	MOV DPTR,#TAB
CGRAM_LOOP:	 CLR A
	MOVC A,@A+DPTR
	LCALL WRITE_DATA
	INC DPTR
	DJNZ R4, CGRAM_LOOP
	RET
;*******字符串************
TAB:	DB 04H,04H,1FH,15H,1FH,04H,04H,00H
	END