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Zumo 32U4 LCD

Problem/symptom: LCD shows 8 blocks (same symptom as photographed and described here Zumo 32U4 LCD shows 8 black squares (photo attached)).

The LCD has been working until today.

What I did (not sure if this has anything to do with the LCD issue):

  1. Removed the front blade, the forward emitter IR LED holder and the front sensor array
  2. Uploaded the “Balancing” example, and tried balancing
  3. Turned off the power switch on the main board
  4. Put back the front blade, the forward emitter IR LED holder and the front sensor array
  5. Uploaded “BlinkLEDs” example, the LEDs blink.
    This is when I noticed the LCD issue.
    What I have tried:
  6. Re-seated the LCD board
  7. Uploaded “LCDBasics” example
  8. Adjusted the LCD contrast using a screw driver
    No change.
    Any help would be appreciated.


The “BlinkLEDs” example does not use the LCD, so not seeing anything useful on the LCD when that program runs is expected, but the “LCDBasics” example should cause something to show up. Can you post some pictures of your Zumo with the LCD installed? Is it possible at some point the LCD was installed incorrectly while the Zumo was powered (through either the batteries or the USB port)?

- Patrick

  1. BlinkLED – Understood. I used it to confirm the issue is not the entire Zumo.
  2. LCDBasics — it doesn’t show anything else other than the 8 blocks (as shown in the picture). The picture shows that the LCD display when Zumo is powered via USB. The battery is in but the switch is OFF. The display is the same when only powered via battery (with the switch on).
    3.The battery was in but the switch was OFF when I re-seated the LCD (no USB connection). I don’t recall there was anytime that I installed/moved the LCD when the power was on (either via USB connection or the power switch).

Thanks for the extra information. It seems like your LCD is probably damaged. Please email us at support@pololu.com with your order info and a reference to this thread and we can help you out with a replacement.

- Patrick

Email sent as instructed. Thanks for your help.