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LCD help needed

Hello EveryBody, I am working on LCD (16x2) and i have built some of my ideas about LCD programming but i am using Assembly language for my LCD, well as all things was going sweet so as every programmer is having something wrong ... (in starting) my problem specification is that i am using that LCD in 8-bit mode and i have connected my AT89C2051 (with some pull-ups)
P1 DB
P3.7 RS
P3.5 RW
P3.4 E
and i have interfaced my LCD with my MCu but my problem is that i am getting the LCD not working ... (i dont know why) .... i have interfaced my LCD but there only little bit of contrast....i mean to say that there nothing visible... even i move my 10K-ohm-POT to the ground.....

and i have done some programming, so could any one please help me .... (i am really stucked)
any help will be appritiatable.....

<code> ORG 0000H LJMP MAIN ORG 0030H RS EQU P3.7 RW EQU P3.5 EN EQU P3.4
MAIN: LCALL DELAY CLR EN MOV DPTR,#MYCOM LCALL LCD_INI MOV DPTR,#MYDATA LCALL LOOP MOV A,#0C9h LCALL COM LCALL DELAY MOV DPTR,#MYDAT2 LCALL LOOP
AGAIN: SJMP AGAIN
;========================================
COM: MOV P1,A CLR RS CLR RW SETB EN LCALL DELAY CLR EN RET
;========================================
DATAW: MOV P1,A SETB RS CLR RW SETB EN LCALL DELAY CLR EN RET
;========================================
DELAY: MOV R6,#100
HERE2: MOV R7,#250
HERE: DJNZ R7,HERE DJNZ R6,HERE2 RET
;========================================
LCD_INI: CLR A MOVC A,@A+DPTR LCALL COM LCALL DELAY JZ GO_B1 INC DPTR SJMP LCD_INI
GO_B1: RET
;========================================
LOOP: CLR A MOVC A,@A+DPTR LCALL DATAW LCALL DELAY INC DPTR JZ GO_B2 SJMP LOOP
GO_B2: RET
;========================================
MYCOM: DB 38H,0EH,06,01,84H,0
MYDATA: DB "DAREDEVIL",0
MYDAT2: DB "GUNS AND ROSES",0
;======================================== END
</code>

Asif Ali "DareDevil"

Parents

0 Asif Ali over 18 years ago

This is the Code which worked for me, and also there is the pin configuration of My MCu (AT89C2051) with the LCD, Hoping that it will help the Noob Programmers (just like me) ;-)

VSS ----> GROUND (PIN-NO 1 ON LCD)
VCC ----> +5V (PIN-NO 2 ON LCD)
CONTRAST-> 10KPOT (PIN-NO 3 ON LCD) [ONE SIDE GROUND ONE SIDE +5V]
P3.4 ----> RS (PIN-NO 4 ON LCD)
P3.5 ----> RW (PIN-NO 5 ON LCD)
P3.7 ----> EN (PIN-NO 6 ON LCD)
P1.0 ----> DB0 (PIN-NO 7 ON LCD)
P1.1 ----> DB1 (PIN-NO 8 ON LCD)
P1.2 ----> DB2 (PIN-NO 9 ON LCD)
P1.3 ----> DB3 (PIN-NO 10 ON LCD)
P1.4 ----> DB4 (PIN-NO 11 ON LCD)
P1.5 ----> DB5 (PIN-NO 12 ON LCD)
P1.6 ----> DB6 (PIN-NO 13 ON LCD)
P1.7 ----> DB7 (PIN-NO 14 ON LCD)

CODE FOR 8-BIT HD44780 LCD FOR WRITING "DARE DEVIL" ON LCD

                ORG 0000H
                LJMP MAIN
                ORG 0030H
                RS EQU P3.5
                RW EQU P3.4
                EN EQU P3.7
                                        ;initialization
MAIN:           MOV A,#038H             ;8 bit mode ON, 2 lines, 5*8 font
                LCALL COM               ;first time
                MOV A,#038H             ;second time
                LCALL COM
                MOV A,#038H             ;third time
                LCALL COM
                MOV A,#038H             ;fourth time
                LCALL COM
                MOV A,#00CH             ;display ON, cursor OFF, blink OFF
                LCALL COM
                MOV A,#001H             ;clear screen
                LCALL COM
                MOV A,#006H             ;increase cursor position, scroll display OFF
                LCALL COM
                MOV A,#080H             ;Set DDRAM address to 0 (means to starting)
                LCALL COM               ;initialization End
                MOV A,#'D'              ;data to write on LCD
                LCALL DATAW
                MOV A,#'A'
                LCALL DATAW
                MOV A,#'R'
                LCALL DATAW
                MOV A,#'E'
                LCALL DATAW
                MOV A,#' '
                LCALL DATAW
                MOV A,#'D'
                LCALL DATAW
                MOV A,#'E'
                LCALL DATAW
                MOV A,#'V'
                LCALL DATAW
                MOV A,#'I'
                LCALL DATAW
                MOV A,#'L'
                LCALL DATAW             ;data end
AGAIN:          SJMP AGAIN              ;endless loop
COM:            MOV P1,A                ;command write sequence
                CLR RS
                CLR RW
                SETB EN
                ;LCALL TEST
                CLR EN
                LCALL DELAY
                RET
DATAW:          MOV P1,A                ;data write sequence
                SETB RS
                CLR RW
                SETB EN
                ;LCALL TEST
                CLR EN
                LCALL DELAY
                RET
DELAY:          MOV R6,#50              ;simple delay routine
HERE2:          MOV R7,#255             ;for 0.0124S or 124MS
HERE:           DJNZ R7,HERE
                DJNZ R6,HERE2
                RET
TEST:           JB P3.0,TEST
TEST2:          JNB P3.0,TEST2
                RET
                END

Reply

0 Asif Ali over 18 years ago

This is the Code which worked for me, and also there is the pin configuration of My MCu (AT89C2051) with the LCD, Hoping that it will help the Noob Programmers (just like me) ;-)

CODE FOR 8-BIT HD44780 LCD FOR WRITING "DARE DEVIL" ON LCD

                ORG 0000H
                LJMP MAIN
                ORG 0030H
                RS EQU P3.5
                RW EQU P3.4
                EN EQU P3.7
                                        ;initialization
MAIN:           MOV A,#038H             ;8 bit mode ON, 2 lines, 5*8 font
                LCALL COM               ;first time
                MOV A,#038H             ;second time
                LCALL COM
                MOV A,#038H             ;third time
                LCALL COM
                MOV A,#038H             ;fourth time
                LCALL COM
                MOV A,#00CH             ;display ON, cursor OFF, blink OFF
                LCALL COM
                MOV A,#001H             ;clear screen
                LCALL COM
                MOV A,#006H             ;increase cursor position, scroll display OFF
                LCALL COM
                MOV A,#080H             ;Set DDRAM address to 0 (means to starting)
                LCALL COM               ;initialization End
                MOV A,#'D'              ;data to write on LCD
                LCALL DATAW
                MOV A,#'A'
                LCALL DATAW
                MOV A,#'R'
                LCALL DATAW
                MOV A,#'E'
                LCALL DATAW
                MOV A,#' '
                LCALL DATAW
                MOV A,#'D'
                LCALL DATAW
                MOV A,#'E'
                LCALL DATAW
                MOV A,#'V'
                LCALL DATAW
                MOV A,#'I'
                LCALL DATAW
                MOV A,#'L'
                LCALL DATAW             ;data end
AGAIN:          SJMP AGAIN              ;endless loop
COM:            MOV P1,A                ;command write sequence
                CLR RS
                CLR RW
                SETB EN
                ;LCALL TEST
                CLR EN
                LCALL DELAY
                RET
DATAW:          MOV P1,A                ;data write sequence
                SETB RS
                CLR RW
                SETB EN
                ;LCALL TEST
                CLR EN
                LCALL DELAY
                RET
DELAY:          MOV R6,#50              ;simple delay routine
HERE2:          MOV R7,#255             ;for 0.0124S or 124MS
HERE:           DJNZ R7,HERE
                DJNZ R6,HERE2
                RET
TEST:           JB P3.0,TEST
TEST2:          JNB P3.0,TEST2
                RET
                END

Children

0 Jonny Doin over 18 years ago in reply to Asif Ali

Congratulations. Now that you have it working in HW, you can try your original code, using DPTR and MOVC to write asciiz strings.
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0 Asif Ali over 18 years ago in reply to Jonny Doin

Thanks sir Jhonny i have tested my MOVC and DPTR code its working like dream .... :-)
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