LCD program :help required

[kiranmayik]

lcd_send_command( hd44780

hi everyone,
i tried interfacing at89c51 with 20X2 lcd display(ODM-20216S).
i have connected port1 to LCD and P3.0 to RS, P3.1 to R/W, P3.2 to E.
but the LCD is not showing any output.
this is the code:



;communicating with lcd
;checking busy flag before sending data, command to lcd
; P1= data pin, P3.0=RS, P3.1=R/W, P3.2=E pins
ORG 0H

MOV A,#38H ;initialize lcd 2 lines
ACALL COMMAND ;issue command

MOV A,#0EH ;lcd on, cursor on
ACALL COMMAND
MOV A,#02H ;return home
ACALL COMMAND
MOV A,#01H ;clear lcd command
ACALL COMMAND
MOV A,#06H ;shift cursor right
ACALL COMMAND
MOV A,#80H ;cursor:line 1,position 0
ACALL COMMAND
MOV A,#'L' ;display letter L
ACALL DATADISP
MOV A,#'C'
ACALL DATADISP
MOV A,#'D'
ACALL DATADISP
HERE:
SJMP HERE ;stay here


COMMAND:
ACALL READY ;check if lcd ready
MOV P1,A ;issue command code
CLR P3.0 ;RS=0 for command
CLR P3.1 ;R/W=0 to write to lcd
SETB P3.2 ;E=1 for H-to-L pulse
ACALL DELAY
CLR P3.2 ;E=0, latch in
RET


DATADISP:
ACALL READY ;check if lcd ready
MOV P1,A ;issue data
SETB P3.0 ;RS=1 for data
CLR P3.1 ; R/W=0 to write to lcd
SETB P3.2 ;E=1 for H-to-L pulse
ACALL DELAY ;give lcd some time
CLR P3.2 ;E=0, latch in
RET


READY:
SETB P1.7 ;make P1.7 input port
CLR P3.0 ;RS=0 access commang register
SETB P3.1 ;R/W=1 read command register
;read command register and check busy flag
BACK:
CLR P3.2 ;E=0 for L-to-H pulse
ACALL DELAY ;give lcd some time
SETB P3.2 ;E=1 L-to-H pulse
JB P1.7,BACK ;stay until busy flag=0
RET


DELAY:
MOV R3,#50
HERE1: MOV R4,#255
HERE2: DJNZ R4,HERE2
DJNZ R3,HERE1
RET
END


i'm not sure how much delays to give.do i have to give delay at the starting for power on.if so how much?and approximately how much delay is required for the enable pin.

please help.
thank you.

 

[nandhu015]

Hai

Here is the tutorial
**broken link removed**

If your lcd is based on HD44780 (the commands make me to think so)
Here is the timings

http://home.iae.nl/users/pouweha/lcd/lcd0.shtml#hd44780

Happy coding
Nandhu

 

[sofi_je]

hi everyone,
i tried interfacing at89c51 with 16X2 lcd display (hd44780)
i have connected port1 to LCD and P1.0 to RS, P1.1 to R/W, P1.2 to E.
but the LCD is not showing any output

Added after 2 minutes:

hi everyone,
i tried interfacing at89c51 with 16X2 lcd display (hd44780)
i have connected port1 to LCD and P1.0 to RS, P1.1 to R/W, P1.2 to E.
but the LCD is not showing any output


any one please help to complete my lcd circuit

 

[vibeeshpv]

Also put some delays between the write enale signals..ten chk the pot for the contrast adjustment...

 

[shafee001]

dear
this is source code of developed program used for lcd 16*1

;LCD interface 89s52
;LCD		8952
;D7  14		p1.7
;D6  13		p1.6
;D5  12		P1.5
;D4  11		p1.4
;EN  6		p1.3
;RS  4		p1.2	
;GND 1,3,5		
;VCC  2

#INCLUDE "8051EQU.INC"
LCD_DATA_4 .equ P1.4
LCD_DATA_5 .equ P1.5
LCD_DATA_6 .equ P1.6
LCD_DATA_7 .equ P1.7
LCD_RS .equ P1.2
LCD_EN .equ P1.3

; RESET
   .ORG   0H
   AJMP   START
; INTERRUPTS  (not used)        ;place interrupt routines at appropriate
                                ;memory locations
   .ORG   03H                   ;external interrupt 0
    RETI
   .ORG   0BH                   ;timer 0 interrupt
    RETI
   .ORG   13H                   ;external interrupt 1
    RETI
   .ORG   1BH                   ;timer 1 interrupt
    RETI
   .ORG   23H                   ;serial port interrupt
    RETI
   .ORG   25H                   ;locate beginning of rest of program
INITIALIZE:                     ;set up control registers

    MOV   R4,#00H
    MOV   A,#00H
    MOV   TCON,#00H
    MOV   TMOD,#00H
    MOV   PSW,#00H             
    MOV   IE,#00H               ;disable interrupts
    RET
LCD_INITIALIZE:
    NOP
	mov P1, #20h
	CLR LCD_RS
	SETB LCD_EN
	ACALL DELAYMS
	CLR LCD_EN
	ACALL DELAYMS
	mov a, #28h
	ACALL LCD_SEND_COMMAND
	mov a, #0ch
	ACALL LCD_SEND_COMMAND
	mov a, #02h
	ACALL LCD_SEND_COMMAND
	RET

LCD_SEND_COMMAND:
	mov 20H,a
	ACALL LCD_DATA
	clr LCD_RS
	setb LCD_EN
	ACALL DELAYMS
	clr LCD_EN
	ACALL DELAYMS

	mov a,20H
	swap a
	ACALL LCD_DATA
	clr LCD_RS
	setb LCD_EN
	ACALL DELAYMS
	clr LCD_EN
	ACALL DELAYMS
	ret

LCD_SEND_DATA:
	mov 20H,a
	ACALL LCD_DATA
	setb LCD_RS
	setb LCD_EN
	ACALL DELAYMS
	clr LCD_EN
	ACALL DELAYMS

	mov a,20H
	swap a
	ACALL LCD_DATA
	setb LCD_RS
	setb LCD_EN
	ACALL DELAYMS
	clr LCD_EN
	ACALL DELAYMS
	ret

LCD_DATA: 
	clr c
	mov 20h,a
	mov c,4h
	mov LCD_DATA_4, c
	mov c,5h
	mov LCD_DATA_5, c
	mov c,6h
	mov LCD_DATA_6, c
	mov c,7h
	mov LCD_DATA_7, c
; MOV   20H,A         ;Save A for low nibble
; ORL   P1,#0F0h    ;Bits 4..7 <- 1
; ORL   A,#0Fh        ;Don't affect bits 0-3
; ANL   P1,A        ;High nibble to display
; MOV   A,20H
 	RET

LCD_CLEAR:
	MOV a,#01H
	ACALL LCD_SEND_COMMAND
	RET

LCD_SEND_SPACES:
	MOV R4,#20H
LOOP_SPACES:
	MOV A,#' '
	ACALL LCD_SEND_DATA
	DJNZ R4,LOOP_SPACES
	RET	


DELAYMS:                        ;millisecond delay routine
   MOV   R7,#00H
LOOPA:                          
   INC   R7
   MOV   A,R7
   CJNE   A,#0FFH,LOOPA
   RET

DELAYHS:                        ;half second delay above millisecond delay
   MOV   R6,#00H
   MOV   R5,#002H
LOOPB:
   INC   R6
   ACALL   DELAYMS
   MOV   A,R6
   JNZ   LOOPB
   DEC   R5
   MOV   A,R5
   JNZ   LOOPB
   RET

DELAY1S:                        ;one second delay above millisecond delay
   MOV   R6,#00H
   MOV   R5,#004H
LOOPC:
   INC   R6
   ACALL   DELAYMS
   MOV   A,R6
   JNZ   LOOPC
   DEC   R5
   MOV   A,R5
   JNZ   LOOPC 
   RET

DELAY5S:		;5 SECONDS DELAY
   MOV   R6,#00H
   MOV   R5,#010H
LOOPD:
   INC   R6
   ACALL   DELAYMS
   MOV   A,R6
   JNZ   LOOPD
   DEC   R5
   MOV   A,R5
   JNZ   LOOPD 
   RET

DELAY20S:		;20 SECONDS DELAY
   MOV   R6,#00H
   MOV   R5,#030H
LOOPE:
   INC   R6
   ACALL   DELAYMS
   MOV   A,R6
   JNZ   LOOPE
   DEC   R5
   MOV   A,R5
   JNZ   LOOPE 
   RET

WRITE_MOBISERVE:
	mov a, #'M'
	ACALL LCD_SEND_DATA
	mov a, #'O'
	ACALL LCD_SEND_DATA
	mov a, #'B'
	ACALL LCD_SEND_DATA
	mov a, #'I'
	ACALL LCD_SEND_DATA
	mov a, #'S'
	ACALL LCD_SEND_DATA
	mov a, #'E'
	ACALL LCD_SEND_DATA
	mov a, #'R'
	ACALL LCD_SEND_DATA
	mov a, #'V'
	ACALL LCD_SEND_DATA

	ACALL LCD_SEND_SPACES

	mov a, #'E'
	ACALL LCD_SEND_DATA
	mov a, #'-'
	ACALL LCD_SEND_DATA
	mov a, #'E'
	ACALL LCD_SEND_DATA
	mov a, #'g'
	ACALL LCD_SEND_DATA
	mov a, #'y'
	ACALL LCD_SEND_DATA
	mov a, #'p'
	ACALL LCD_SEND_DATA
	mov a, #'t'
	ACALL LCD_SEND_DATA



	RET
;************************* program entry *********************************************
START:                          ;main program (on power up, program starts at this point)
	ACALL INITIALIZE
	ACALL LCD_INITIALIZE
	ACALL LCD_CLEAR
	ACALL WRITE_MOBISERVE
	MOV P1,#01H
	ACALL DELAY1S
FREEZ:
	NOP
	CPL P1.1
	CPL P1.0
	ACALL DELAY1S
	AJMP FREEZ

.END