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.