contrast.
The voltage however varies for different LCDs (Some are happy with a 0-5V
range others need a -Ve supply. You will need to check the data sheet
One simple thing to try is to wire a potentiometer (the value is not
critical , 1K - 10K is fine) between GND and 5V with the wiper going to the
contrast pin (sometimes labelled VLCD).
As you vary the voltage (by turning the pot) you should see the LCD 'dots'
change intensity.
It is easy to get caught out thinking the LCD is dead/not initialised and
its just the contrast setting.
Although, to he honest, in this case it is MOST likely the init sequence as
David points out. :-)
Have a look at AVRfreaks.net - I am sure that there would be some sample
code for a text based LCD there
HTH
Ivan
----- Original Message -----
From: "Dave VanHorn" <dvanhorn@dvanhorn.org>
To: <AVR-Chat@yahoogroups.com>; <AVR-Chat@yahoogroups.com>
Sent: Saturday, April 23, 2005 11:27 AM
Subject: Re: [AVR-Chat] New LCD will not work.
>
> LCD displays generally don't display anything
> useful on powerup, but you should be able to vary
> the contrast voltage, and get black squares.
> If you can't get that, then even if you are
> talking to it right, you may never know it.
>
> Other than that, it's TIMING, TIMING, TIMING.
> Do ALL the init steps, and insure that all your delays meet spec plus a
bit.
> You can always trim the delays back to spec+1 after you get it talking.
>
> It can be tedious, since you don't usually get
> anything viewable until you get all of it right.
>
> I can sympathize, I just went through this with a
> small 16 bit color LCD on another project, with a
> VERY long init sequence, where the parts that
> were correct, were poorly documented. :)
>
>
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