piclist 2001\11\01\081121a >
Thread: LCD panel init problems
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face BY : Wollenberg, Frank email (remove spam text)



> -----Original Message-----
> From: Steve Campbell [DigitalTechRemoveMEspamWORLDNET.ATT.NET]
> Sent: Thursday, November 01, 2001 12:27 AM
> To: PICLIST@spam@spamMITVMA.MIT.EDU
> Subject: Re: [EE]: LCD panel init problems
>
> Are you using it in 4 or 8 bit mode?  4 bit is a little
> harder to init but
> there are many sources for LCD code available.  Check for
> some sample code
> and compare your init code with other's.
>
>

I'm using LCD in 8 bit mode only. 4 bit has the problem that both the
controlling uC and the LCD controller must be synchronous. LCD modules has
only internal reset circuitry, there's no external reset pin available. So
let us assume:

1)      both uC and LCD module are powered up correctly
2)      uC initialize the LCD module correctly
3)      uC must send 8 bit in two 4bit chunks to the LCD
4)      after the first 4bit, the uC only resets (powering problem, ESD are
what ever)
5)      the uC powers up and will initialize the LCD module

But: the LCD is awaiting the 2nd 4bit chunk, the uC is sending the first
4bit of initialization data.
I don't see, how to synchronize uC and LCD without resetting the LCD module
via a power down/up cycle.

Any ideas ?

Frank

GSP Sprachtechnologie GmbH
Frank Wollenberg
HW-Entwicklung
Tel.:   +49 (0)30 769929-78
Fax:    +49 (0)30 769929-12
eMail:  RemoveMEf.wollenberg.....spamspamBeGonegsp-berlin.de


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Tel.:  +49 (0)30 769929-0
Fax:   +49 (0)30 769929-12
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