Circuitpython: Rotary encoder support

[tannewt]

SAMD51 has a peripheral for it.

[sommersoft]

Just wanted to make some notes here. I was skimming through Noridc documentation, and noticed that nRF52x also has rotary encoder as a peripheral. Not surprising, since it's M4 based.

They refer to it as "Quadrature decoder" or "QDEC". Here are links to the documentation:

• nRF52832: QDEC

• nRF52840: QDEC

[microbuilder]

The Arduino nRF52 Repo contains a RotaryEncoder library with both HW and SW implementations for this, just as a reference. If a common API is added at the HAL layer, it shouldn't be too complicated to add nRF52 support used the QDEC peripheral or GPIO.

[ladyada]

making a note here that SAMD has very fixed pins for QDEC - so for that platform, at least, we should just DIY with a timer interrupt - an existing one would probably be fine as the checking code is very small

[tannewt]

Anyone mind if I punt this to 4.0?