I've just received my Duemilanove and, of course, did everything I had the hardware to do - PWM, ADC, Serial comm, and so on - and everything worked flawlessly. The reason for saying is that when I got to the LCD examples things started getting inconsistent (which makes me believe it's the LCD itself). It wasn't the usual "Hey, dudes - I'm getting jibberish on my display" but rather the fact that it was functioning perfectly for about 5 seconds and then would only display properly if (this sounds weird) it were "twisted" a certain way. My discovery of this "remedy" came when bending wires to make the display lay flat on the desk. Keep in mind we're only talking MINOR pressure applied to the LCD's board - no more than it would experience from moving 16 22-gauge solid core wires around that've been soldered into it. The next problem is that it slowly began losing track of cursor position, flickered the backlight and, eventually, wouldn't initialize at all (still showed blocks on top row with backlight)...
I'd really hate to throw it away as it's the only one I have and i don't have any needs for other components to fill an order big enough to justify shipping another one. Has anyone else experienced this and is it enough to diagnose a brick? Just wanted to ask around before the display had to meet a properly-disposed-of end...
then would only display properly if (this sounds weird) it were "twisted" a certain way.
I agree with Paul. This is the classic behavior that results from a broken trace or a cold solder joint. It's time to get out the magnifying glass and the soldering iron.
I had checked the joints but not very closely so wicking everything out and starting over may, indeed, be the best option. What's frustrating is that while it's a standard HD44780, the lead pads are configured in two columns instead of the one row along the top/bottom of the display which makes it difficult to see both sides of the board where the wires connect. Every other display of this class seems to have the 16 pins in one row so it can be fitted with a header and dropped right into a breadboard. Might be worth making some kind of adapter...
At any rate you guys have definitely given me a few things to consider. Should be able to get to it in the next day or so.
Some people plug these directly into a Mega. You have to power the LCD and the backlight with I/O pins which requires some more software, but the tradeoff is that you get software control of both those functions. If you want to pursue this approach further then search out 'jrraines' on this forum and ask him about it.
Well it's certainly not the prettiest thing in the world but I was able to convert my 2x8 into a 16x1 for breadboarding. The suggestions to re-wire/solder must have been correct as this course of action has resulted in a perfectly consistent display even with light pressure applied. The construction of the 16x1 adapter should also relieve the wires/on-board solder joints from all stress as well.
This is all probably obvious to some but just thought I'd "document" my solution in case someone else should run across the same issue.
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