Re: [avr-chat] LCD corruption

[Royce Pereira]

Hi,

On Wed, 28 Sep 2005 20:59:20 +0530, Andy Warner <address@hidden> wrote:

> Royce Pereira wrote:
> > [...]
> > I'm using my LCD in 4 bit mode- is this mode more susceptible to noise?
>
> How are the remaining 4 data lines terminated ?

They are not terminated. Should they be?
I have not experienced a problem with this in some other projects.
> > I think I'll try adding 10n (or less) capacitors from each of the LCD  
> > pins to gnd. Any comments on this would be helpful..
>
> Doubtful, IMHO.

The improvement from adding a pull-down resistor to E led me to believe  
that a low pass filter on the LCD pins might work. Yet to try it out,  
though.

> A couple of extra questions - you said the problem only occurs
> when the 220V side of the relays is active ? Without 220V,
> energising the relays results in no corruption ?

Without any load connected to the relays, theres no problem.


> Have you tried switching a non-inductive 220V load instead
> of the solenoids ?

No, not yet.

> Without knowing more of your design, you might want to try and isolate
> whether the problem is on your board (feel free to post a url to pdfs
> of the layout), or back through the power supply ?

I expect the CPU to hang or something in case of a noise on signal or  
supply lines.
But the CPU works fine. Only the LCD gives the problem.

Thanks for all the replies,
--Royce.

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