3pi LCD defect


looks like as I destroyed the LCD of the 3pi.
It stays “green”.
I´m not sure how it happens exactly.
I detected it after a battery change. Might be I ripped the LCD out
before switching of 3pi???
Looks like the 328p output PINs are ok …I generate some output pulse for
PD2 …PD7 and they look ok.

Does it make sense to analyse the LCD module …or just order a new one?

I wonder if you have a SW for checking the LCD module?
Just to see if the LCD chip does any meaningful thing as response to some commands?

Before the battery change I did some 180 degree turns at full speed.
Could it be a mechanical problem?

In some manner 3pi has room for improvement. Thinking about a new LCD …brought up the
idea of using a I2C module and win some output pins. But the I2C (TWI) are used for the IR sensors.
Swapping here the Ports/Pins would give more flexibility for extending the 3pi.

Have you tried adjusting the potentiometer on the bottom of the robot? If you turn the 3pi over, you will see two potentiometers that can be adjusted with a small screwdriver. the one that is closest to the ball caster adjusts the contrast for the LCD. It could be that the contrast was inadvertently turned all the way to one direction.

Hi alzabo,

thanks for the hint … meanwhile I did some more checks. Power input of the LCD of the does not take any current.
So seems to be dead.
Tricky part is, to get a new one. $10 for the LCD is no issue …but the transport cost etc. makes it expensive.
So I think about a improved solution …like bluetooth to a smart phone.
Or recycle an old nokia display.
I will see.


If your LCD went from working to not working between battery changes, then I think the most likely explanation is that you accidentally plugged it in wrong when replacing it. The LCD header is not shrouded or keyed, so it does not enforce proper alignment or orientation, and it isn’t difficult to unintentionally plug the LCD in offset by a set of pins or rotated 180 degrees. Unfortunately, doing this can kill the LCD.

If you are interested in a replacement LCD, please email us (and reference this forum thread) and we should at least be able to get you a discount.

- Ben