WiFi on FiPy issues with Expansion Board 3

  • The Wifi does not work when plugged into power from both the Expansion Board 3 as well as USB, which I am using for debugging. When plugged into the expansion board sensors and power but not usb, or vice versa, everything works but I need them both plugged in for coding reasons. Thanks in advance!

  • We do not have schematics publically available for the Expansionboard 3, though I'm not completely sure what is/ is not working for you.

    You mention powering the Fipy directly in the expansionboard using the Vin header (right next to the battery connector i presume) with 3.3V? Then, you attached the USB cable, and the expansionboard got damaged?

    Could you verify the Fipy is receiving power on Vin, and generating 3.3V on the output, using the presumably broken expansionboard with a multimeter (of course without attaching the separate 3.3V supply).

    The mosfet you encircled is, if memory serves me correctly, the power switching mosfet, switching the power source between battery and USB, depending on which is connected, perhaps explaining why it is broken, as the 3.3V was backfeeding, though I would expect the USB voltage to overpower your 3.3V source.

    You also mention you're able to flash the PIC, does it then also show up on your computer as a COM port? Could you also let me know of the voltage on the Vin pin without the Fipy present?

    There is no way to disable USB power going to the Fipy, without doing some physical damage to the board (ie, remove one of the components or scratching a trace).

  • @robert-hh looks like this unidentified chip is what's toast on the one board. It's marked J13 and looks to be some type of dual mosfet? There's what looks like a tiny hairline fizzure horizontally across it.


  • @robert-hh The ATM board was outputting 3v3 to the Vin pin of the Expansion board 3.1, so when USB was plugged in, the PC was back-feeding 5v to the ATM board thru the USB/Expansion board 3.. The ATM board fortunately didn't get damaged. But one of the expansion boards did. Nothing looks visibly burned and no odd smells. After removing and troubleshooting the expansion board separate from our project, I can flash the PIC to the latest firmware with DFU-util but the Fipy won't connect via USB. I tested the Fipy on another expansion board 3.1 and it appears OK. Is there any schematic available for the Expansion Board 3.1? I'm trying to see if there's a way to disable the USB power on the board since it's getting good power elsewhere, and we should only need the USB for diagnostics once things are up and running.

  • @Thomas-Johnson said in WiFi on FiPy issues with Expansion Board 3:

    This voltage goes to the Vin on the expansion board 3

    With Vin, do you mean the battery connector or Vin of the FiPy module at Pin 24? The latter will have ~5V when USB is connected.

  • @jcaron We have an ATM90E36 hooked up, which has a wall outlet plug which goes to 9V then 3.3V to the microcontroller. This voltage goes to the Vin on the expansion board 3 so we dont have to use usb power when it is in the field. It seems that when there are two power sources the FiPy esp32 does not work.

  • @Thomas-Johnson I'm not sure I understand, isn't the power from the expansion board coming from the USB port? Or are you using a battery as well? Or another power source? Can you clarify what is connected where exactly?

Log in to reply

Pycom on Twitter