16x2 Not Displaying Right

Forum 2005-2010 (read only) Hardware Troubleshooting
1

After breadboarding my 16x2 LCD screen it worked fine. But now that I have soldered it onto my PCB, it doesn't display properly.

It displays zeros, degree signs and arrows instead of the text I want. What could be the problem?

[I don't have a good enough camera to show my soldering]

2

I managed to get it working with this code: http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1237405175/13

kinda!

It showed some grarbage. Then it displayed the right text when I pressed a button. Then the program ran through in about half a second! But that's just my rubbsih prgramming!

I also tried to put a generic sketch on, which displayed garbage again.

Ben

3

I may be way off base but your LCD may need to be initialized. I don't have first hand knowledge of this but you may find some clues to your puzzle by searching for something like "LCD init" or "LCD initialize" or "LCD reset". My only experience with LCD displays is using a driver board like the LCD117 sold by ModernDevice and others. However, while using that board I did experience something similar to what you are saying and was able to reset the driver board. I also vaguely remember reading a thread and initialization of the LCD unit came up in the conversation. I'm pretty sure it was on this forum. I'll look and see what I find too.

Before bothering with that though, have you checked all your connections for continuity? Are all wires routed to the correct pins? Have you checked for shorts or debris at the PCB?

Wish I could offer more help. I think, like you alluded, that a good picture would help with diagnosis as would seeing the sketch you are running.

Best of luck.
Sam

4

I also grabbed one of those boards from moderndevice.com , it makes me feel so lazy, but it sure gets the job done. It's ridiculously easy to use, and its most likely compatible with your LCD. I'd consider it if you can't solve your problem.

5

I had a similar problem with my 16x2 Sparkfun LCD... The problem ended up being that the demo code I was using didn't initialize the LCD in the setup(). Added the necessary code and had no issues.