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Adafruit Feather M0 Basic Proto


The Adafruit Feather M0 Basic Proto is a thin, light ARM development board with an onboard battery connector and charger for 3.7 V lithium polymer batteries, charging status indicator and user LEDs, native USB connector, 20 I/O pins, and a small prototyping area.

Adafruit Feather M0 Basic Proto


  • ATSAMD21G18A ARM Cortex-M0+ processor at 48 MHz

  • 32.768 kHz crystal oscillator

  • 256 KiB flash memory and 32 KiB of RAM

  • Battery connector and charger for 3.7 V lithium polymer batteries

  • Charging indicator LED

  • User LED

  • Reset button

  • Native USB port

Supported Features

The adafruit_feather_m0_basic_proto board configuration supports the following hardware features:






Nested vector interrupt controller



Can be used with LittleFS to store files









I/O ports



Serial port



Serial Peripheral Interface port



USB device

Other hardware features are not currently supported by Zephyr.

The default configuration can be found in the Kconfig file boards/arm/adafruit_feather_m0_basic_proto/adafruit_feather_m0_basic_proto_defconfig.

Connections and IOs

The Adafruit Feather M0 Basic Proto Learn site 1 has detailed information about the board including pinouts 2 and the schematic 3.

System Clock

The SAMD21 MCU is configured to use the 32.768 kHz external oscillator with the on-chip PLL generating the 48 MHz system clock.

Serial Port

The SAMD21 MCU has 6 SERCOM based USARTs. On the Adafruit Feather M0 Basic Proto, SERCOM0 is the Zephyr console and is available on pins 0 (RX) and 1 (TX).

SPI Port

The SAMD21 MCU has 6 SERCOM based SPIs. On the Adafruit Feather M0 Basic Proto, SERCOM4 is available on pin 22 (MISO), pin 23 (MOSI), and pin 24 (SCK).

USB Device Port

The SAMD21 MCU has a USB device port that can be used to communicate with a host PC. See the USB Samples sample applications for more, such as the USB CDC ACM Sample Application sample which sets up a virtual serial port that echos characters back to the host PC.

Programming and Debugging

The Adafruit Feather M0 Basic Proto ships with a BOSSA compatible SAM-BA bootloader. The bootloader can be entered by quickly tapping the reset button twice.


  1. Build the Zephyr kernel and the Hello World sample application:

    west build -b adafruit_feather_m0_basic_proto samples/hello_world
  2. Connect the Adafruit Feather M0 Basic Proto to your host computer using USB

  3. Connect a 3.3 V USB to serial adapter to the board and to the host. See the Serial Port section above for the board’s pin connections.

  4. Run your favorite terminal program to listen for output. Under Linux the terminal should be /dev/ttyACM0. For example:

    $ minicom -D /dev/ttyACM0 -o

    The -o option tells minicom not to send the modem initialization string. Connection should be configured as follows:

    • Speed: 115200

    • Data: 8 bits

    • Parity: None

    • Stop bits: 1

  5. Tap the reset button twice quickly to enter bootloader mode

  6. Flash the image:

    west build -b adafruit_feather_m0_basic_proto samples/hello_world
    west flash

    You should see “Hello World! arm” in your terminal.