8 Bit LCD Control Using 8051

;8 bit LCD routines with check busy flag before sending data, command to LCD
;*************************************************************
LCD DATA P1 ;define LCD data port on port 1
BUSY BIT LCD.7 ;define LCD busy flag
E BIT P2.2 ;define LCD enable pin on port 2.2
RS BIT P2.0 ;define LCD register select pin on port 2.0
RW BIT P2.1 ;define LCD read/write pin on port 2.1
;*************************************************************
ORG 00H

LCD_INIT:
MOV A,#38H ;2 line 5x7
ACALL COMMAND
MOV A,#0CH ;LCD on cursor on
ACALL COMMAND
MOV A,#01H ;clear LCD
ACALL COMMAND
MOV A,#06H ;shift cursor right
ACALL COMMAND
DISPLAY:MOV A,#81H
ACALL COMMAND
MOV DPTR,#TEST
ACALL DISP_STRING
MOV A,#0C1H
ACALL COMMAND
MOV DPTR,#TEST+0EH
ACALL DISP_STRING
HERE: SJMP HERE
;=============================================================
COMMAND:
ACALL READY ;is LCD ready?
MOV LCD,A ;issue command code
CLR RS ;RS=0 for command
CLR RW ;R/W=0 to write to LCD|
SETB E ;E=1 for H-to-L pulse
CLR E ;E=0 ,latch in
RET
;=============================================================
DATA_DISPLAY:
ACALL READY ;is LCD ready?
MOV LCD,A ;issue data
SETB RS ;RS=1 for data
CLR RW ;R/W=0 to write to LCD
SETB E ;E=1 for H-to-L pulse
CLR E ;E=0 ,latch in
RET
;=============================================================
READY:
SETB BUSY ;make P1.7 input port
CLR RS ;RS=0 access command reg
SETB RW ;R/W=1 read command reg
;read command reg and check busy flag
BACK:
CLR E ;E=1 for H-to-L pulse
SETB E ;E=0 H-to-l pulse
JB BUSY,BACK ;stay until busy flag=0
RET
;=========================================================
DISP_STRING:
CLR A ;A=0
MOV R7,#00H ;R7=0
NEXT_CHAR:
INC R7 ;R7+1
MOVC A,@A+DPTR
ACALL DATA_DISPLAY
MOV A,R7
CJNE R7,#0EH,NEXT_CHAR
RET
;=============================================================
TEST: DB "8-Bit LCD Test","By 80C51 MCU's"
END