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Moderators: Ajay, Junied , abbas1707, Arun Kumar V, pdi33, Shailesh NAYAK, ۞ TPS ۞, shyam, sashijoseph

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anee

Mon Apr 07 2008, 03:56AM

Registered Member #3763

Joined: Thu Aug 30 2007, 03:56AM

Posts: 17
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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

geetikagupta

Mon Apr 07 2008, 10:47AM

Registered Member #6257

Joined: Sun Feb 24 2008, 11:40PM

Posts: 34
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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

This post has been thanked 1 time

anee

geetikagupta

Mon Apr 07 2008, 10:54AM

Registered Member #6257

Joined: Sun Feb 24 2008, 11:40PM

Posts: 34
Thanked 4 times in 4 posts

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

This post has been thanked 1 time

anee

anee

Mon Apr 07 2008, 10:56AM

Registered Member #3763

Joined: Thu Aug 30 2007, 03:56AM

Posts: 17
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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...

pdi33

Mon Apr 07 2008, 11:57AM

Registered Member #1329

Joined: Mon Jun 04 2007, 09:28AM

Posts: 655
Thanked 144 times in 140 posts

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

* inspired to develop,developing to inspire *

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anee

pdi33

Mon Apr 07 2008, 12:09PM

Registered Member #1329

Joined: Mon Jun 04 2007, 09:28AM

Posts: 655
Thanked 144 times in 140 posts

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.

* inspired to develop,developing to inspire *

This post has been thanked 1 time

anee

sashijoseph

Mon Apr 07 2008, 07:23PM

Registered Member #5870

Joined: Mon Feb 04 2008, 06:26PM

Posts: 552
Thanked 124 times in 117 posts

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

Let there be music........

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anee

Amit Radha

Mon Apr 07 2008, 07:47PM

Registered Member #4203

Joined: Sun Sep 30 2007, 04:52AM

Posts: 205
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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

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anee

sashijoseph

Mon Apr 07 2008, 08:41PM

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Joined: Mon Feb 04 2008, 06:26PM

Posts: 552
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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?

Let there be music........

This post has been thanked 1 time

anee

anee

Tue Apr 08 2008, 03:58AM

Registered Member #3763

Joined: Thu Aug 30 2007, 03:56AM

Posts: 17
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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...