Frank,

 What you say about synchronization may be true, but I've never had
 anything like that happen to me, and I use 4 bit mode all the time.
 The syncronization comes in by using the handshake signals provided
 by the LCD Module (ie strobe).   As far as I can tell, there is no
 reason to have the LCD controller and the microcontroller synchronized.
 Let me know why you think what you said is true, and I'll definitely
 listen.  I'm open to learning new things.  It's just that I've never
 heard this before, nor have I experienced it.

                                                 Regards,

                                                   Jim








>> -----Original Message-----
>> From: Steve Campbell [mailto:DigitalTech@WORLDNET.ATT.NET]
>> Sent: Thursday, November 01, 2001 12:27 AM
>> To: PICLIST@MITVMA.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:  f.wollenberg@gsp-berlin.de
>
>
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