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22 KiB


This port brings MicroPython to SAMD21x18 based development boards under the name
CircuitPython. Supported boards include:

- Adafruit CircuitPlayground Express
- Adafruit Feather M0 Basic
- Adafruit Feather M0 Express
- Adafruit Metro M0 Express
- Adafruit M0 Bluefruit LE
- Arduino Zero
- Arduino MKR Zero


All of the boards share the same core pin functionality but call pins by
different names. The table below matches the pin order in
`the datasheet <>`_
and omits the pins only available on the largest package because all supported
boards use smaller version.

===================== =================== =============== =========================== ====================== ================ ================== ========================= ================ ================================ ====================== ================
`` `board`
--------------------- --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Datasheet arduino_mkrzero arduino_zero circuitplayground_express feather_m0_adalogger feather_m0_basic feather_m0_express gemma_m0 metro_m0_express sparkfun_samd21_mini sparkfun_samd21_dev trinket_m0
===================== =================== =============== =========================== ====================== ================ ================== ========================= ================ ================================ ====================== ================
PA02 ``A0`` ``A0`` ``A0`` / ``SPEAKER`` ``A0`` ``A0`` ``A0`` ``A0`` / ``D1`` ``A0`` ``A0`` ``A0`` ``D1`` / ``A0``
PB08 ``L`` ``A1`` ``A7`` / ``TX`` ``A1`` ``A1`` ``A1`` ``A1`` ``A1`` ``A1``
PB09 ``BATTERY`` ``A2`` ``A6`` / ``RX`` ``A2`` ``A2`` ``A2`` ``A2`` ``A2`` ``A2``
PA04 ``A3`` ``A3`` ``IR_PROXIMITY`` ``A3`` ``A3`` ``A3`` ``D0`` / ``TX`` / ``SDA`` ``A3`` ``A3`` ``A3``
PA05 ``A4`` ``A4`` ``A1`` ``A4`` ``A4`` ``A4`` ``D2`` / ``RX`` / ``SCL`` ``A4`` ``A4``
PA06 ``A5`` ``D8`` ``A2`` ``D8`` / ``GREEN_LED`` ``NEOPIXEL`` ``D8`` ``D8`` ``D8`` ``D4`` / ``TX``
PA07 ``A6`` ``D9`` ``A3`` ``D9`` ``D9`` ``D9`` ``D9`` ``D9`` ``D9`` ``D3`` / ``RX``
PA08 ``D11`` / ``SDA`` ``D4`` ``MICROPHONE_DO`` ``D4`` / ``SD_CS`` ``D4`` ``D4`` ``D4`` ``D0`` / ``SDA``
PA09 ``D12`` / ``SCL`` ``D3`` ``TEMPERATURE`` / ``A9`` ``D3`` ``D3`` ``D3`` ``D2`` / ``SCL``
PA10 ``D2`` ``D1`` / ``TX`` ``MICROPHONE_SCK`` ``D1`` / ``TX`` ``D1`` / ``TX`` ``D1`` / ``TX`` ``D1`` / ``TX`` ``D1`` / ``TX`` ``D1`` / ``TX`` ``D13``
PA11 ``D3`` ``D0`` / ``RX`` ``LIGHT`` / ``A8`` ``D0`` / ``RX`` ``D0`` / ``RX`` ``D0`` / ``RX`` ``D0`` / ``RX`` ``D0`` / ``RX`` ``D0`` / ``RX``
PB10 ``D4`` ``MOSI`` ``MOSI`` ``MOSI`` ``MOSI`` ``MOSI`` ``MOSI``
PB11 ``D5`` ``SCK`` ``SCK`` ``SCK`` ``SCK`` ``SCK`` ``SCK``
PA12 ``SD_MOSI`` ``MISO`` ``REMOTEIN`` / ``IR_RX`` ``MISO`` ``MISO`` ``MISO`` ``MISO`` ``MISO``
PA14 ``SD_CS`` ``D2`` ``BUTTON_B`` / ``D5`` ``D2`` ``D2`` ``D2``
PA15 ``SD_MISO`` ``D5`` ``SLIDE_SWITCH`` / ``D7`` ``D5`` ``D5`` ``D5`` ``D5`` ``D5`` ``D5``
PA16 ``D8`` / ``MOSI`` ``D11`` ``MISO`` ``D11`` ``D11`` ``D11`` ``D11`` ``D11`` / ``MOSI`` ``D11``
PA17 ``D9`` / ``SCK`` ``D13`` ``D13`` ``D13`` / ``RED_LED`` ``D13`` ``D13`` ``D13`` ``D13`` / ``SCK`` / ``BLUE_LED`` ``D13`` / ``BLUE_LED``
PA18 ``D10`` ``D10`` ``D10`` ``D10`` ``D10`` ``D10`` ``D10``
PA19 ``D10`` / ``MISO`` ``D12`` ``D12`` ``D12`` ``D12`` ``D12`` ``D12`` / ``MISO`` ``D12``
PA20 ``D6`` ``D6`` ``MOSI`` ``D6`` ``D6`` ``D6`` ``D6`` ``D6`` ``D6``
PA21 ``D7`` ``D7`` ``SCK`` ``D7`` / ``SD_CD`` ``D7`` ``D7`` ``D7``
PA22 ``D0`` ``SDA`` ``SDA`` ``SDA`` ``SDA`` ``SDA`` ``SDA`` ``SDA``
PA23 ``D1`` ``SCL`` ``REMOTEOUT`` / ``IR_TX`` ``SCL`` ``SCL`` ``SCL`` ``L`` / ``D13`` ``SCL`` ``SCL`` ``SCL``
PB22 ``D14`` / ``TX`` ``FLASH_CS`` ``D30`` / ``TX1``
PB23 ``D13`` / ``RX`` ``NEOPIXEL`` / ``D8`` ``D31`` / ``RX1``
PA28 ``BUTTON_A`` / ``D4``
PB02 ``A1`` ``A5`` ``A5`` / ``SDA`` ``A5`` ``A5`` ``A5`` ``A5`` ``A5``
PB03 ``A2`` ``A4`` / ``SCL`` ``YELLOW_LED`` ``YELLOW_LED``
===================== =================== =============== =========================== ====================== ================ ================== ========================= ================ ================================ ====================== ================

Here is a table about which pins can do what in CircuitPython terms. However,
just because something is listed, doesn't mean it will always work. Existing use
of other pins and functionality will impact your ability to use a pin for your
desired purpose. For example, only certain combinations of SPI pins will work
because they use shared hardware internally.

===================== ======== ========= ========= ======= ======= ======= ========= ========= ======= ========== ========== ========= ========= ========= ============ ======= ======= =========
`` `analogio` `audioio` `bitbangio` `busio` `digitalio` `pulseio` `touchio`
--------------------- ------------------- --------- ------------------------- -------------------------------------------------------------------------------------- ------------ ---------------- ---------
Datasheet AnalogIn AnalogOut AudioOut I2C OneWire SPI I2C - SDA I2C - SCL OneWire SPI - MISO SPI - MOSI SPI - SCK UART - RX UART - TX DigitalInOut PulseIn PWMOut TouchIn
===================== ======== ========= ========= ======= ======= ======= ========= ========= ======= ========== ========== ========= ========= ========= ============ ======= ======= =========
PA00 **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes**
PA01 **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes**
PA02 **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes**
PA03 **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes**
PB08 **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes**
PB09 **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes**
PA04 **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes**
PA05 **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes**
PA06 **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes**
PA07 **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes**
PA08 **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes**
PA09 **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes**
PA10 **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes**
PA11 **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes**
PB10 **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes**
PB11 **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes**
PA12 **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes**
PA13 **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes**
PA14 **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes**
PA15 **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes**
PA16 **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes**
PA17 **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes**
PA18 **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes**
PA19 **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes**
PA20 **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes**
PA21 **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes**
PA22 **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes**
PA23 **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes**
PB22 **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes**
PB23 **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes**
PA27 **Yes** **Yes** **Yes** **Yes** **Yes** **Yes**
PA28 **Yes** **Yes** **Yes** **Yes** **Yes** **Yes**
PA29 **Yes** **Yes** **Yes** **Yes** **Yes** **Yes**
PA30 **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes**
PA31 **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes**
PB02 **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes**
PB03 **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes** **Yes**
===================== ======== ========= ========= ======= ======= ======= ========= ========= ======= ========== ========== ========= ========= ========= ============ ======= ======= =========


An ARM compiler is required for the build, along with the associated binary
utilities. They can be installed as follows:

- Ubuntu

.. code-block:: shell

sudo add-apt-repository ppa:team-gcc-arm-embedded/ppa
sudo apt-get install gcc-arm-embedded

- Arch Linux

.. code-block:: shell

sudo pacman -S arm-none-eabi-gcc arm-none-eabi-newlib

For other systems, the `GNU Arm Embedded Toolchain <>`_
may be available in binary form.

The latest available package from team-gcc-arm-embedded is used to produce the
binaries shipped by AdaFruit. Other compiler versions, particularly older
ones, may not work properly. In particular, the ``gcc-arm-none-eabi`` package
in Debian Stretch is too old.

The compiler can be changed using the ``CROSS_COMPILE`` variable when invoking


Before building the firmware for a given board, there are two additional steps.
These commands should be executed from the root directory of the repository

1. There are various submodules that reside in different repositories. In order
to have these submodules locally, you must pull them into your clone, using:

.. code-block:: shell

git submodule update --init --recursive

2. The MicroPython cross-compiler must be built; it will be used to pre-compile
some of the built-in scripts to bytecode. The cross-compiler is built and
run on the host machine, using:

.. code-block:: shell

make -C mpy-cross

Build commands are run from the ``circuitpython/ports/atmel-samd`` directory.

To build for a given board you must specify it by setting ``BOARD``. For example:

.. code-block:: shell

make BOARD=feather_m0_basic

Board names are the directory names in the `boards <>`_ folder.


Arduino Bootloader

If your board has an existing Arduino bootloader on it then you can use bossac
to flash MicroPython. First, activate the bootloader. On Adafruit Feathers you
can double click the reset button and the #13 will fade in and out. Finally,
run bossac:

tools/bossac_osx -e -w -v -b -R build-feather_m0_basic/firmware.bin

No Bootloader via GDB

This method works for loading MicroPython onto the Arduino Zero via the
programming port rather than the native USB port.

Note: These instructions are tested on Mac OSX and will vary for different

openocd -f ~/Library/Arduino15/packages/arduino/hardware/samd/1.6.6/variants/arduino_zero/openocd_scripts/arduino_zero.cfg

In another terminal from ``micropython/atmel-samd``:

arm-none-eabi-gdb build-arduino_zero/firmware.elf
(gdb) tar ext :3333
(gdb) load
(gdb) monitor reset init
(gdb) continue



All boards are currently configured to work over USB rather than UART. To
connect to it from OSX do something like this:

screen /dev/tty.usbmodem142422 115200

You may not see a prompt immediately because it doesn't know you connected. To
get one either hit enter to get `>>>` or do CTRL-B to get the full header.

Mass storage

All boards will also show up as a mass storage device. Make sure to eject it
before resetting or disconnecting the board.

Port Specific modules

.. toctree::