Left encoder on Zumo does not work right

I bought the Pololu Zumo 32U4 Robot Kit (No Motors) with two 75:1 Micro Metal Gear Motor HP with Extended Motor Shaft.
I assembled it and everything seemed to work fine. :smiley:
But then I loaded the Encoder Example and recognized that the counter of the left encoder only went from 0 to 1, 1 to 0 and so on. :frowning:
Does anybody know what causes this problem?
Iā€™m pretty sure that I mounted the encoder in the right way.
And now Iā€™m a little bit afraid to disassemble the Zumo again. Especially to pull the magnetic encoder from the shaft without damaging the motor because it is pretty stiff on the shaft.
So, is there anything I could try before to find the error?


I am sorry you are having trouble getting your Zumo 32U4 encoder to work. Can you tell me more about your setup? Are you running our Zumo32U4 encoder sketch unmodified? Do you have anything connected to digital pin 8 or PE2 (the two pins reading the left encoder outputs)? Can you also post a picture that clearly shows the magnetic encoder disk on the motor shaft?


Hello Jon,

yes, I used your original sketch and I have nothing else connected then the original kit does.

Posting a picture or something else was exactly what I tried to avoid, because to do this I have to disassemble the zumo of what Iā€™m afraid to do in terms of destroying something.

Anyway I did it, shot the pictures and even changed the motors against each other while reassembling.

The error stays on the left side:
The before on the right side working proper motor and magnetic encoder disc does not count on the left side and the before working wrong on the left side motor and magnetic encoder disc does now works proper on the right side.

Is the sensor be defect?

Thanks for disassembling your Zumo 32U4. It does seem like something is wrong with the encoder sensors, so we would like to get a better look at what could be going on. Can you email us with your salesorder information and reference this thread?