lcd

hey..me havin a similar prod as yun..my lcd displayed da required msg a couple of times...but thereafter its just da bars...i adjusted da contrast,tried programmin da chip again...but nothin...n i checked da voltages at da crystal input..they r fine..so da controller is ok...any suggestions...plz...this is urgent...i need to submit da proj in 3 days..

thanks in advance

well, im using d following assembly language code in my project(using AT89S52),
if dis is wat u require, then hav a look, its working fine in my project




;LCD PORT DEFINITIONS
DATAPORT EQU P0
EN EQU P1.2
RW EQU P1.1
RS EQU P1.0
D7 EQU P0.7

ORG 0000h
LJMP MAIN


MAIN:

MOV DATAPORT,#0FFH
ACALL LCD216 ;LCD INITIALISATION
ACALL LCDCLR
ACALL RETHOME
ACALL DONCOFF ;LCD INITIALISED
ACALL LCDCLR
ACALL FCBFL
ACALL COMMAND
MOV DPTR,#TABLE15
ACALL WRITE
ACALL FCBSL
ACALL COMMAND
MOV DPTR,#TABLE25
ACALL WRITE
RET

TABLE15: DB 'RESULT MODE',0 ;U MAY WRITE HERE WATEVER U WAN2 DISPLAY
TABLE25: DB 'STARTING...',0








;LCD ROUTINES

CHKBUSY: ;Checks for the status of the LCD
SETB D7
CLR RS
SETB RW

LOOP:
CLR EN
SETB EN
JB D7,LOOP
RET

DISPLAY:
ACALL CHKBUSY
MOV DATAPORT,A
SETB RS
CLR RW
SETB EN
CLR EN
RET

COMMAND:
ACALL CHKBUSY
MOV DATAPORT,A
CLR RS
CLR RW
SETB EN
CLR EN
RET

LCD216:
MOV A,#38H ;FORCES 2 X 16 MATRIX
ACALL COMMAND
RET

LCDCLR:
MOV A,#01H
ACALL COMMAND
RET

RETHOME:
MOV A,#02H ;RETURN HOME
ACALL COMMAND
RET

DONCOFF:
MOV A,#0CH
ACALL COMMAND
RET

DONCB:
MOV A,#0FH
ACALL COMMAND
RET

FCBFL:
MOV A,#80H
ACALL COMMAND
RET

FCBSL:
MOV A,#0C0H
ACALL COMMAND
RET

WRITE:
CLR A
MOVC A,@A+DPTR
JZ BACK2
ACALL DISPLAY
INC DPTR
JMP WRITE

BACK2: RET



END


sorry for those irritating tabs n identations

waaauuu....., dis is good, no iritating tabs n identations, d windows "notepad" makers need to learn smthng frm here...

hey...thanks...i don think anythin's wrong wid my code..but still...will try usin urs n check...thanks again..n yes...no tabs..:)...i was wonderin at tabs u talkin abt...

well, either ur code has some problem or ur hardware. so try sending ur circuit and/or ur code and maybe we can find the bug which is bugging u

well i saw ur code from the other forum topic. looks fine to me. can u send the circuit so that we can have an idea about how it is wired?.check the following:
1. power supply. preferably connect a 0.1uF decoupling cap across vcc and gnd and as close to microcontroller as possible.
2. connct two 33pF caps across the xtal and gnd.

And have you hooked up a proper power-on reset ckt?
Try checking loose connections to the LCD.

To add onto what pdi33 said, i suggest u use 0.1uF tantalum caps. They make a world of a change.
Check the supply o/p on the board depending on how well ur board is ul come to know how noisy ur gnd or vcc is. A friend of mine had a terrible time cleaning his ground
I was lucky dint face that problem.

Dont worry ul get amazing advice over here, have faith... I have learnt alot from this forum.

Good luck :bye

Oops.....when you can,avoid tantalums like plague.They are prone to leakage and when compared to ceramics are fairly 'slow'.They do have a speed advantage over hefty electrolytics but when choosing between 0.1uF ceramic or tant' always prefer ceramics.Ceramics also have a lower self inductance and are non-polar whereas tants' are essentially polarized(correct me if I'm wrong) and may lead to mishaps when reverse connected.They do have a size advantage over electrolytics though.
Amit..where did you get this info yaar?

thanks all...hey pdi33...my hardware's pretty simple...lcd on p1 n da 3 control signals from p3.0,3.1,3.2...i forgot abt da decoup capa completely...is it dat imp...will add it n try again today...n i m average at solderin,but shashijoseph i checked da continuity on each pin..should i do anythin else...n where can i get good moderately priced dev boards...atleast i won't hav to worry abt da solderin then...
thanks again... :-)