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Zumo Shield for Arduino equivalent to Zumo 32U4 encoder pins

Hi, I’m wiring up a pair of Hall effect encoders to the Zumo Shield for Arduino. In the documentation for the quadrature encoders on the Zumo 32U4 it states:

  • Digital pin 7, or PE6, reads the right encoder XORed signal using external interrupt INT6.
  • Digital pin 8, or PB4, reads the left encoder XORed signal using pin change interrupt PCINT4.
  • Digital pin 23 (analog pin 5), or PF0, reads the right encoder channel B.
  • Pin PE2 reads the left encoder channel B.

While it’s fairly clear what the digital pins 7, 8 and 23 would be on the Arduino shield, what is the equivalent of PE2? I can’t seem to find where I’d plug my encoder connection.

Thanks!

Hello, maltheim.

The PE2 pin is specific to the ATmega32U4, and it is not exposed on all Arduino boards that use the 32U4, so the Zumo Shield for Arduino does not have a dedicated pass-through connection for it. If you are using an Arduino-compatible board like our A-Star 32U4 Prime, the PE2 pin is brought out on the 2x3 grouping of pins toward the middle of the board, as shown in this pinout diagram from the A-Star 32U4 Prime product page.

The Zumo 32U4 is just using that pin to take a digital reading of channel B of the encoder. If you are adding XOR gates to read the encoders the same way the Zumo 32U4 does and use the Zumo 32U4 library, you can use any free pin that is capable of taking digital readings; you would just have to modify the library to refer to that pin instead.

Brandon

Ahh, understood. I was I suppose hoping I could use the library without modification, but as you say it’s just a matter of choosing a different digital pin for channel B.

Thanks for the clarification!

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