Comments: Pro Micro & Fio v3 Hookup Guide


Comments 10 comments

  • What is the type of the USB connector? There are several types of the mini and micro. Thanks

  • I’m a bit confused on the FIO hookup guide. I was under the impression the I2C connections are on A4 & A5. Though the image shows them on D2 & D3. Which is correct?

    • D2 and D3 is correct for this version of the FIO; it uses the ATmega32U4, which has those pins assigned to I2C.

      You’re right that any Arduino that uses an ATmega328 (like the Uno, Pro Mini, Pro, etc.) would have the I2C pins on A4/A5.

      • So a got a couple of the Sparkfun 32U4 v3 FIOs, imagine my disappointment when I noticed what appeared to be a slam dunk for mounting an Adafruit ADC 16 bit analog board straight on top, only to find the SDA and SCL were swapped!

        Any suggestions for swapping the pins short of artful soldering of a miniature metal helix?

  • If you have problems uploading code with this error using the Pro Micro on a Linux machine:

     avrdude: ser_recv(): programmer is not responding
     avrdude: butterfly_recv(): programmer is not responding

    try following these instructions from Arduino => They need to change some udev rules. There was a customer had the same problem but got it working after changing the settings.

  • It looks like pins 14 and 17 are swapped on the hookup guide (hopefully not swapped on the board!).

    Can you confirm/deny this is the case?

    • Ahhhh…. The short answer is all the boards work correctly. Somewhere along the line something got mislabled (it might be on the actual part). I think the current boards/schematics are all correct though. On the Fio the ISP header works, on the Pro Micro the SPI pins are all there. Otherwise I suggest ignoring the labels and just seeing what works.

      • I should clarify: the blue pin numbers on the hookup guide (not the board) look swapped. So maybe just needs a photoshop on the image to avoid confusion. Suspect the board is fine and the graphic is just mistaken.

  • As mentioned in this tutorial the Arduino add files on do not work for Arduino V1.5. I have fixed this and put up a set of files that work with Arduino V1.5.5 These are available from

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