translation missing: en.general.accessibility.skip_to_content

Feather M0 Express ATSAMD21 Cortex M0 (ID: 3403)

SKU 2159
1 review
£19.96 inc VAT
£16.63 ex VAT
26 in stock.

The Feather M0 Express is specifically designed for use with CircuitPython (created by Adafruit), a beginner orientated version of MicroPython, a small but full-featured version of the popular Python programming language specifically for use with circuitry and electronics. This tiny development board is not limited to the CircuitPython programming language and can be used with the Arduino IDE.

Easy reprogramming: the Feather M0 comes pre-loaded with the UF2 bootloader, which looks like a USB storage key. Simply drag firmware on to program, no special tools or drivers needed! It can be used to load up CircuitPython, PXT MakeCode or Arduino IDE (it is bossa-compatible)

At the Feather M0's heart is an ATSAMD21G18 ARM Cortex M0+ processor, clocked at 48 MHz and at 3.3V logic, the same one used in the new Arduino Zero. This chip has a whopping 256K of FLASH (8x more than the Atmega328 or 32u4) and 32K of RAM (16x as much)! This chip comes with built in USB so it has USB-to-Serial program & debug capability built in with no need for an FTDI-like chip.

The Feather M0 Express uses the extra space left over to add a Mini NeoPixel, 2 MB SPI Flash storage and a little prototyping space. You can use the SPI Flash storage like a very tiny hard drive. When used in CircuitPython, the 2 MB flash acts as storage for all your scripts, libraries and files. When used in Arduino, you can read/write files to it, like a little datalogger or SD card, and then with our helper program, access the files over USB.

Note: CircuitPython is still in beta. You can pick up one of these Feather M0 Expresses if you want to try it out - maybe even help Adafruit find bugs and make improvements!

Note: Lipoly battery and USB cable not included.


  • Dimensions: 2.0" x 0.9" x 0.28" (51mm x 23mm x 8mm) without headers soldered in
  • Weight: 5 grams
  • ATSAMD21G18 @ 48MHz with 3.3V logic/power
  • 256KB of FLASH + 32KB of RAM
  • 32.768 KHz crystal for clock generation & RTC
  • 3.3V regulator with 500mA peak current output
  • USB native support, comes with USB bootloader and serial port debugging
  • You also get tons of pins - 20 GPIO pins
  • Hardware Serial, hardware I2C, hardware SPI support
  • PWM outputs on all pins
  • 6 x 12-bit analog inputs
  • 1 x 10-bit analog ouput (DAC)
  • Built in 100mA lipoly charger with charging status indicator LED
  • Pin #13 red LED for general purpose blinking
  • Power/enable pin
  • 4 mounting holes
  • Reset button

Feather M0 Express ATSAMD21 Cortex M0 Resources

UF2 Bootloader

ATSAMD21 Datasheet (the main chip on the Feather M0)

Fritzing object in the Adafruit Fritzing Library

EagleCAD PCB files in GitHub

Feather M0 Express Pinout

'Classic' Feather M0 Bootloader - You'll need to program it in using an ST-Link, JLink or other SWD-capable programmer.HEX available in the github repo

Product overview and datasheets

Circuit Python Downloads

Latest Circuit Python release

Circuit Python GitHub