assembly code for Lcd display

[ved]

I have  assembly code for lcd display I want to display letter on lcd (keil compiler )but letters are not scrolling.
code is here
     ORG 0H
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
MOV A,#18H
ACALL COMNWRT
ACALL DELAY ;give LCD some time
MOV A,#’J’ ;display letter J
ACALL DATAWRT ;call display subroutine
ACALL DELAY ;give LCD some time
MOV A,#’D’ ;display letter D
ACALL DATAWRT ;call display subroutine
AGAIN: SJMP AGAIN ;stay here
COMNWRT: ;send command to LCD
MOV P1,A ;copy reg A to port 1
CLR P2.0 ;RS=0 for command
CLR P2.1 ;R/W=0 for write
SETB P2.2 ;E=1 for high pulse
ACALL DELAY ;give LCD some time
CLR P2.2 ;E=0 for H-to-L pulse
RET
DATAWRT: ;write data to LCD
MOV P1,A ;copy reg A to port 1
SETB P2.0 ;RS=1 for data
CLR P2.1 ;R/W=0 for write
SETB P2.2 ;E=1 for high pulse
ACALL DELAY ;give LCD some time
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

[Ashutosh Bhatt]

ur code seems to be correct. check out for ur hardware connections

[ved]

I know my code is correct but I want some massage scrolling all time how to do?

[Ashutosh Bhatt]

use command to shift entire display left or right in continuous loop

[ved]

I don’t know how to create continous loop

[SHAH DISHANT H.]

Hi,

 

For scrolling you have to give command 0x18 and you have given that also.

But you have to give this command after you have displayed data. here you are giving command before displaying data.

 

Correct this and it will work for sure.

 

All the ebst.

[ved]

you mean this code

                                 ORG 0H
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

MOV A,#’J’ ;display letter J
ACALL DATAWRT ;call display subroutine
ACALL DELAY ;give LCD some time
MOV A,#’D’ ;display letter D
ACALL DATAWRT ;call display subroutine
MOV A,#18H
ACALL COMNWRT
ACALL DELAY ;give LCD some time
AGAIN: SJMP AGAIN ;stay here
COMNWRT: ;send command to LCD
MOV P1,A ;copy reg A to port 1
CLR P2.0 ;RS=0 for command
CLR P2.1 ;R/W=0 for write
SETB P2.2 ;E=1 for high pulse
ACALL DELAY ;give LCD some time
CLR P2.2 ;E=0 for H-to-L pulse
RET
DATAWRT: ;write data to LCD
MOV P1,A ;copy reg A to port 1
SETB P2.0 ;RS=1 for data
CLR P2.1 ;R/W=0 for write
SETB P2.2 ;E=1 for high pulse
ACALL DELAY ;give LCD some time
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

I tried but letters are not scrolling all time

[Author]

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