here some samples ASM code of 8051(89C51) ...try load this programe and test ur microcontroller circuit ...make sure ur microcontroller circuit is working properly...i confirm that this code is working.best of luck! i recomanded that to use LCD from OPTREX company....
---------------------example1----------------------------------
;Check busy flag before sending data, command to LCD
;P1=data pin
;P2.0 connected to RS pin
;P2.1 connected to R/W pin
;P2.2 connected to E pin
ORG
MOV A,#38H ;init. LCD 2 lines,5x7 matrix
ACALL COMMAND ;issue command
MOV A,#0EH ;LCD on, cursor on
ACALL COMMAND ;issue command
MOV A,#01H ;clear LCD command
ACALL COMMAND ;issue command
MOV A,#06H ;shift cursor right
ACALL COMMAND ;issue command
MOV A,#86H ;cursor: line 1, pos. 6
ACALL COMMAND ;command subroutine
MOV A,#'N' ;display letter N
ACALL DATA_DISPLAY
MOV A,#'O' ;display letter O
ACALL DATA_DISPLAY
HERE: SJMP HERE ;STAY HERE
COMMAND: ACALL READY ;is LCD ready?
MOV P1,A ;issue command code
CLR P2.0 ;RS=0 for command
CLR P2.1 ;R/W=0 to write to LCD
SETB P2.2 ;E=1 for H-to-L pulse
CLR P2.2 ;E=0 ,latch in
RET
DATA_DISPLAY:
ACALL READY ;is LCD ready?
MOV P1,A ;issue data
SETB P2.0 ;RS=1 for data
CLR P2.1 ;R/W=0 to write to LCD
SETB P2.2 ;E=1 for H-to-L pulse
CLR P2.2 ;E=0, latch in
RET

READY:
SETB P1.7 ;make P1.7 input port
CLR P2.0 ;RS=0 access command reg
SETB P2.1 ;R/W=1 read command reg
;read command reg and check busy flag
BACK:CLR P2.2 ;E=1 for H-to-L pulse
SETB P2.2 ;E=0 H-to-L pulse
JB P1.7,BACK ;stay until busy flag=0
RET
END

------------------------example2------------------------------

;calls a time delay before sending next data/command
; P1.0-P1.7 are connected to LCD data pins D0-D7
; P2.0 is connected to RS pin of LCD
; P2.1 is connected to R/W pin of LCD
; P2.2 is connected to E pin of LCD
ORG
MOV A,#38H ;init. LCD 2 lines,5x7 matrix
ACALL COMNWRT ;call command subroutine
ACALL DELAY ;give LCD some time
MOV A,#0EH ;display on, cursor on
ACALL COMNWRT ;call command subroutine
ACALL DELAY ;give LCD some time
MOV A,#01 ;clear LCD
ACALL COMNWRT ;call command subroutine
ACALL DELAY ;give LCD some time
MOV A,#06H ;shift cursor right
ACALL COMNWRT ;call command subroutine
ACALL DELAY ;give LCD some time
MOV A,#84H ;cursor at line 1,pos. 4
ACALL COMNWRT ;call command subroutine
ACALL DELAY ;give LCD some time
MOV A,#'N' ;display letter N
ACALL DATAWRT ;call display subroutine
ACALL DELAY ;give LCD some time
MOV A,#'O' ;display letter O
ACALL DATAWRT ;call display subroutine
AGAIN: SJMP AGAIN ;stay here
COMNWRT: ;send command to LCD
MOV P1,A ;copy reg A to port1
CLR P2.0 ;RS=0 for command
CLR P2.1 ;R/W=0 for write
SETB P2.2 ;E=1 for high pulse
CLR P2.2 ;E=0 for H-to-L pulse
RET
DATAWRT: ;write data to LCD
MOV P1,A ;copy reg A to port1
SETB P2.0 ;RS=1 for data
CLR P2.1 ;R/W=0 for write
SETB P2.2 ;E=1 for high pulse
CLR P2.2 ;E=0 for H-to-L pulse
RET
DELAY: MOV R3,#50 ;50 or higher for fast CPUs
HERE2: MOV R4,#255 ;R4=255
HERE: DJNZ R4,HERE ;stay until R4 becomes 0
DJNZ R3,HERE2
RET
END

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