Support pin IO41 (aka ANTENNA_SWITCH)

[JonNelson]

Support pin IO41 (aka ANTENNA_SWITCH), which allows a user to switch from the built-in antenna to the uFL antenna. This pin is only on the "D" series of Unexpected Maker S3 series of boards.

https://unexpectedmaker.com/shop.html#!/FeatherS3-D/p/759221736

[JonNelson]

It's not clear how one might differentiate among "D" and non-"D" series at build time, or if there is value in doing so.
While I have one of these devices (and a uFL antenna), it's not clear how I might comprehensively test this.

[tannewt]

This is fine with me. I'm ok having it on the non-D version.

[grgrant]

The pin was always available as microcontroller.pin.GPIO41 but this is a nice shortcut so thanks @JonNelson

I tested the new release and it correctly aliases pin GPIO41.

Adafruit CircuitPython 10.3.0-alpha.1-7-gb9305fc290 on 2026-05-07; FeatherS3 with ESP32S3
>>> import board
>>> import microcontroller
>>> dir(board)
['__class__', '__name__', 'A0', 'A1', 'A10', 'A11', 'A12', 'A2', 'A3', 'A4', 'A5', 'A6', 'A7', 'A8', 'A9', 
'AMB', 'ANTENNA_SWITCH', 'BATTERY', 
'D0', 'D1', 'D10', 'D11', 'D12', 'D13', 'D14', 'D15', 'D16', 'D17', 'D18', 'D19', 'D21', 'D22', 'D23', 'D24', 'D25', 'D4', 'D5', 'D6', 'D9', 'I2C', 'I2C2', 'IO0', 'IO1', 'IO10', 'IO11', 'IO12', 'IO14', 'IO15', 'IO16', 'IO17', 'IO18', 'IO3', 'IO33', 'IO35', 'IO36', 'IO37', 'IO38', 'IO39', 'IO4', 'IO41', 'IO43', 'IO44', 'IO5', 'IO6', 'IO7', 'IO8', 'IO9', 'LDO2', 'LED', 'MISO', 'MOSI', 'NEOPIXEL', 'NEOPIXEL_POWER', 'RX', 'SCK', 'SCL', 'SCL2', 'SDA', 'SDA2', 'SPI', 'STEMMA_I2C', 'STEMMA_I2C2', 'STEMMA_VERTICAL_I2C', 'TX', 'UART', 'VBAT', 'VBAT_SENSE', 'VBUS', 'VBUS_SENSE', 'VOLTAGE_MONITOR', '__dict__', 'board_id']
>>> microcontroller.pin.GPIO41 == board.ANTENNA_SWITCH
True
>>>