I have an Arduino Mega board with a 16x2 LCD connected to it. I have left it powered on for a couple of weeks. This morning I noticed that it was displaying only part of the characters. Now it is connected to the Arduino board via a breadboard, so my immediate thoughts is one of the wires came loose. I did find that the Data bit 3 (I have it wired in 4-bit parallel mode). So I thought for sure that was my problem, but after checking all the other wires and rebooting the board, the problem still persists:( Could I have damaged the LCD? What other things should I try? The first row of characters appear to be cut in half horizontally and the first 8 characters are very dim.
Yeah, there is a piece of conductive rubber strip between the circuit board and the liquid crystal panel. This strip may be displaced on the top left corner. Has it been dropped or subject to extreme temperature?
I'm assuming this 16x2 is a display based on the HD44780 type chips. The issue would clearly between on the LCD; a flaw in a data connection would change which character was being displayed but not cause it to display only part of a character. None of the power, enable, etc lines could have that effect.
If it were displaying only one line that could be due to faulty initialization in software.
Yes it is a 16x2 based on the HD44780. It has not been dropped or subjected to extreme pressure or temperature...at least I don't recall any. I don't think it is SW related, since I uploaded one of the LCD examples and the display did the same thing. I also don't thing it is Arduino HW, since I changed the pins used from my code to the ones used by the LCD example.
I ordered a couple more and will give those a shot...is this a fairly common problem?
I have 7 LCD panels and none of them has shown this problem. I would look at the rubbers.
Second pic on this forum post. The gray strips are what I'm talking about. Inspect (without actually opening it) the strip on the top left corner as well as the metal twisted end on that corner (see 10 L-shaped black ends?). If that end is loose, that corner will have poor contact. Try pushing that corner down to see if the LCD flickers and improves and then release pressure to see if it worsens. I suspect the metal twist ends now.
Here is more info: I suspect you have type 1 connection, which is conductive rubber.