LCd (44780 controller)

[Martin Mehner]

Hi!

help wanted! I have several (more thant 10 pieces now) of that 2x16
char LCD here. In former times I wrote a pic assembly program that
uses this one - worked great)
I came up to use it again and: does not work!
So i connected the display to an application known as working well and
guess what: not working!
I tried 10 different displays now all show the same behaviour.
Anybody has a clou what went wrong?

Mart

ps: I take the usually precaution to ESD. And I assume not ALL of the
displays can be defective since they withstood all my "treatings" so
far

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[Rich Webb]

Hi!

help wanted! I have several (more thant 10 pieces now) of that 2x16
char LCD here. In former times I wrote a pic assembly program that
uses this one - worked great)
I came up to use it again and: does not work!
So i connected the display to an application known as working well and
guess what: not working!
I tried 10 different displays now all show the same behaviour.
Anybody has a clou what went wrong?

Not all 44780-style displays have the same characteristics for things
like setup and hold time. If you can't get the docs for that specific
display, try adding a couple of NOPs around the E strobe, etc. A good
scope or logic analyzer might help show what's happening.

 

[Martin Mehner]

Not all 44780-style displays have the same characteristics for things
like setup and hold time. If you can't get the docs for that specific
display, try adding a couple of NOPs around the E strobe, etc. A good
scope or logic analyzer might help show what's happening.

I'll check that out thou I think it does not need a negative volage
nor it#s a timing problem (I use a PIC clocked @4MHz so every
instruciton is at least a 1us. But it's worth a try anyway).

Thanks to all who answered so far.

Mart

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[Rein Wiehler]

I'll check that out thou I think it does not need a negative volage
nor it#s a timing problem (I use a PIC clocked @4MHz so every
instruciton is at least a 1us. But it's worth a try anyway).

Thanks to all who answered so far.

Mart

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have you used this exact model of LCD before?
Compare the diferrent model numbers you have, not every LCD follows
the same spec.
rw