I purchased an LCD screen (model HD44780) for use with my Arduino. I used Lady Ada's LCD tutorial found here:
I got it hooked up to my breadboard/Arduino but was unable to see text on the screen. Turning the potentiometer caused the solid blocks to show up just like in the tutorial but the Hello World text was not seen.
Here's where the weirdness starts.
Unplugging the 5v supply from the breadboard only dimmed the back light but didn't turn it off. I plugged it back in to get the back light the full brightness
Unplugging the 5v supply from the potentiometer caused everything to work properly. Hello World and all.
So what am I doing wrong? It would seem that with the 5v line removed and with power still getting to the back light, that one of the other output pins being used to feed data to the screen is feeding 3.3v of power to the light. Is that normal? Also, why does removing the 5v line from the potentiometer make everything work?
I tested with my digital multimeter and none of the header pins I soldered to the lcd's 16 pads are touching each other.
Here is a picture of it working. I'm sorry I don't have color coded wires but everything is matched up like in the above mentioned tutorial I linked to.