SAMD21x18

This port brings MicroPython to SAMD21x18 based development boards under the name CircuitPython. Supported boards include the Adafruit CircuitPlayground Express, Adafruit Feather M0 Express, Adafruit Metro M0 Express, Arduino Zero, Adafruit Feather M0 Basic and Adafruit M0 Bluefruit LE.

Pinout

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.

microcontroller.pin board
Datasheet arduino_zero circuitplayground_express feather_m0_adalogger feather_m0_basic feather_m0_express gemma_m0 metro_m0_express trinket_m0
PA00   ACCELEROMETER_SDA       APA102_MOSI   APA102_MOSI
PA01   ACCELEROMETER_SCL       APA102_SCK   APA102_SCK
PA02 A0 A0 / SPEAKER A0 A0 A0 A0 / D1 A0 D1 / A0
PA03                
PB08 A1 A7 / TX A1 A1 A1   A1  
PB09 A2 A6 / RX A2 A2 A2   A2  
PA04 A3 IR_PROXIMITY A3 A3 A3 D0 / TX / SDA A3  
PA05 A4 A1 A4 A4 A4 D2 / RX / SCL A4  
PA06 D8 A2     NEOPIXEL   D8 D4 / TX
PA07 D9 A3 D9 D9 D9   D9 D3 / RX
PA08 D4 MICROPHONE_DO SD_CS       D4 D0 / SDA
PA09 D3 TEMPERATURE / A9         D3 D2 / SCL
PA10 D1 / TX MICROPHONE_SCK D1 / TX D1 / TX D1 / TX   D1 / TX D13
PA11 D0 / RX LIGHT / A8 D0 / RX D0 / RX D0 / RX   D0 / RX  
PB10 MOSI   MOSI MOSI MOSI   MOSI  
PB11 SCK   SCK SCK SCK   SCK  
PA12 MISO REMOTEIN / IR_RX MISO MISO MISO   MISO  
PA13   ACCELEROMETER_INTERRUPT         FLASH_CS  
PA14 D2 BUTTON_B / D5         D2  
PA15 D5 SLIDE_SWITCH / D7 D5 D5 D5   D5  
PA16 D11 MISO D11 D11 D11   D11  
PA17 D13 D13 D13 D13 D13   D13  
PA18 D10   D10 D10 D10   D10  
PA19 D12   D12 D12 D12   D12  
PA20 D6 MOSI D6 D6 D6   D6  
PA21 D7 SCK         D7  
PA22 SDA   SDA SDA SDA   SDA  
PA23 SCL REMOTEOUT / IR_TX SCL SCL SCL L / D13 SCL  
PA24                
PA25                
PB22   FLASH_CS            
PB23   NEOPIXEL / D8            
PA27                
PA28   BUTTON_A / D4            
PA29                
PA30   SPEAKER_ENABLE         NEOPIXEL  
PA31                
PB02 A5 A5 / SDA A5 A5 A5   A5  
PB03   A4 / SCL            

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.

microcontroller.pin 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  
PA24                                    
PA25                                    
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

Building

To build for the Arduino Zero:

make

To build for other boards you must change it by setting BOARD. For example:

make BOARD=feather_m0_basic

Board names are the directory names in the boards folder.

Deploying

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 platforms.

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

Connecting

Serial

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.