All, I got the display working using the example program.  All works well except that the contrast changes about once a second.

I have looked at the program and it appears as though this is set in the initialization of the display (range 0..63 and is set at 39).

Does anyone know why the contrast changes?  Does anyone know how to make it stop changing?  Please advise.

Thanks and Regards,  Jim

I can see that this forum isn't going to be that useful. I can't even get a response to a simple question, let alone the answer.

Your problem is a bit vague. You really need to provide more than 3 lines of you want a response.

Those LCDs are a little flaky. The one I had would have a sharp picture and then as the LCD got warm, lines would start to appear (I doubt it was code related, I couldn't fix it).

Are you using the reset() method? If you reset to clear the screen, you can actually see the screen refresh. These displays aren't very fast, you can really notice when the screen is refreshed. Maybe that's what you're referring to.

Igor,

No, I'm not talking about screen refresh.   When I run the example program (from the cookbook), the displays shows as it does in the writeup regarding the program.  However, the screen gets brighter and dimmer about once a second or so.  I thought maybe the screen color was getting written to with different data, but that doesn't appear to be happening. 

The program doesn't show a "RESET" command (Function), so I added one, but that doesn't make any difference.  I suppose I could have a bad display, but I doubt that is the case either.  I can take a movie of the action if you want to see what I'm talking about.  I would really like to find out what the problem is and how I can take care of it.  The display looks rather good and I have a use for it, but if I can't get it to stay stable, it isn't going to be much good anyway.

I'll take a short movie this weekend, and I'll post it to my website, and I'll leave a link here so it can be accessed. 

Thanks all,

Regards,

 Jim

It could also be the back light. What are you using to power the backlight. Make sure the supply can source enough current. At 3.3V, the unit that I had drew over 200 mA for the back light alone. At higher voltages, the unit draws more current (shunt based voltage regulator I assume..) I had a farily stable operation powering the back light with as little as 2V.

All,

It turned out it was the backlight causing the problem.  If I disconnect the internal supply and run it off an external supply, all is stable and working well.

My unit draws about 60ma for the backlight.  I am going to add a 100uF cap from the LCD supply to ground to see if that helps as suggested in a paper I found on the internet.  If it don't, I'll try adding a resist or from the internal supply to limit the current.  If that don't work, I'll have to go to an external supply.

Thanks Igor for pointing me in the right direction.

Regards,

Jim

 Another question, how does one go about changing text color?

Jim