Add Adafruit Feather RP2040 Prop-Maker

[dhalbert]

@ladyada

Board name

Name is "Prop-Maker", with a hyphen, to match the FeatherWing name; not "PropMaker", and not "Prop Maker".

Pin names

Board-specific pin names were a bit tricky to decide on. Let me know if you have other ideas.

I2S pins

I2S pins match the argument names for the constructor:

audiobusio.I2SOut(
    bit_clock: microcontroller.Pin,
    word_select: microcontroller.Pin,
    data: microcontroller.Pin,
    *, left_justified: bool)

• board.I2S.BIT_CLOCK
• board.I2S_DATA
• board.I2S_WORD_SELECT

Button pin

The button terminal is called EXTERNAL_BUTTON to distinguish it from the on-board board.BUTTON, which is the name it has on the other similar RP2040 Feathers. I decided against BUTTON2 or similar. EXTERNAL_BUTTON is unambiguous.

• board.EXTERNAL_BUTTON

NeoPixel strip control

As with the external button, calling them EXTERNAL_NEOPIXELS and EXTERNAL_NEOPIXELS_POWER makes them unambiguous, and clearly separate from the on-board board.NEOPIXEL. It looks to me like the POWER control is active high. If not, let me know and I'll add _INVERTED.

• board.EXTERNAL_NEOPIXELS
• board.EXTERNAL_NEOPIXELS_POWER

Servo

Not EXTERNAL_SERVO, because there is no onboard servo :)

• board.SERVO

Accelerometer

• board.ACCELEROMETER_INTERRUPT

[dhalbert]

@ladyada

Proto board tested completely:

• Tested all pins are mapped correctly, checking that they can drive an LED.
• Tested external neopixel capability.
• Tested external power switching on/off.
• Tested I2S amp by playing an MP3.
• Tested EXTERNAL_BUTTON as an input.
• Tested STEMMA I2C with a BNO055
• Tested accelerometer, including tap detection via interrupt pin, and tested state of interrupt pin
• Tested battery power capability

I2S_MOD is called out in the schematic, but is permanently pulled up (no spare pin to use to control it)