On Fri, 16 Aug 2002, Vasile Surducan wrote:

>I'ts an interesting effect because the contrast usual must have nothing to
>do with the communication ( and I'm not talking about sharing one cursor
>at two different positions where multiplexation will decrease the contrast
>) If all communication timing are ok then only Vlc must modify the
>contrast. Vlc may be a positive or negative voltage depends on LCD
>characteristics, tipically is somewhere between +2.5 to +4V or -3 to -5V.
>But in your case I think is a 4bit mode error if the 8 bit looks great.

It's not the 'contrast' that changes, the funny codes sent probably
reprogram the display with every command sent. This could cause strange
contrast effects. What happens if you hold the MCU in reset after it
prints something ? Does the contrast become normal ?

Peter

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