Pin configuration support for the UPduino 3.1 (iCE40)

[bsiever]

This PR includes PCF support for the UPduino 3.1: https://tinyvision.ai/products/upduino-v3-1 .

Thanks for a great extension!

[lushaylabs]

Hey @bsiever looks great, I am just doing a sanity check on all the OSs and should have this released later today. Thank you

[lushaylabs]

Thank you again for the amazing contribution, and sorry for the delays, it is my fault I got caught up with some other things, merging this now.

One small question regarding the UPduino I saw that you need to bridge a jumper to use the 12Mhz osc, if you don't use that oscillator does it use an internal clock or are you meant to connect an external clock through one of the IO pins ?

[bsiever]

Thanks and no rush.

I'm not an UPduino expert...but yes, it would need to use an internal oscillator if the external 12MHz isn't connected (bridged or jumpered to another pin). The 12MHz is used for the FTDI. See https://upduino.readthedocs.io/en/latest/tutorials/oscillator.html .