add Adafruit feather, itsybitsy, qtpy board headers

[hathach]

This PR adds board headers for Adafruit

• Feather RP2040
• Itsy Bitsy RP2040
• QT Py RP2040

I didn't see any boards define SPI pin, but the name is very obvious. Let me know if you would like to change the name

• PICO_DEFAULT_SPI
• PICO_DEFAULT_SPI_MOSI_PIN
• PICO_DEFAULT_SPI_MISO_PIN
• PICO_DEFAULT_SPI_SCK_PIN

PS: It would be nice if this PR is merged before #192 , so that it got updated as well.

@ladyada

[lurch]

PICO_DEFAULT_SPI_MOSI_PIN
PICO_DEFAULT_SPI_MISO_PIN

That would make sense if those functions were on fixed pins, but IIRC the "MOSI" and "MISO" pins depend on whether you're using the SPI on the RP2040 in master-mode or slave-mode? Which is why https://www.raspberrypi.org/documentation/rp2040/getting-started/ simply labels them as "SPI RX" and "SPI TX".
See section 4.4.3.15 in https://datasheets.raspberrypi.org/rp2040/rp2040-datasheet.pdf

But I don't want to second-guess how @kilograham will be handling PICO_DEFAULT_SPI_* in #192 , so probably best to hold fire for now 😉

[kilograham]

PICO_DEFAULT_SPI_MOSI_PIN
PICO_DEFAULT_SPI_MISO_PIN

That would make sense if those functions were on fixed pins, but IIRC the "MOSI" and "MISO" pins depend on whether you're using the SPI on the RP2040 in master-mode or slave-mode? Which is why https://www.raspberrypi.org/documentation/rp2040/getting-started/ simply labels them as "SPI RX" and "SPI TX".
See section 4.4.3.15 in https://datasheets.raspberrypi.org/rp2040/rp2040-datasheet.pdf

But I don't want to second-guess how @kilograham will be handling PICO_DEFAULT_SPI_* in #192 , so probably best to hold fire for now wink

ha, i didn't see this, and found it myself. I would want to use TX and RX. Are you currently using these defines?

[hathach]

ha, i didn't see this, and found it myself. I would want to use TX and RX. Are you currently using these defines?

Currently we don't use it at all, just though it would be nice to have. We are happy whichever standard name that you choose. Would you like us to make another PR to change the name to SPI RX & TX ?

[kilograham]

nope i already have merged it in and will fix it up