To make it easy to use for portable projects, Adafruit has added a JST connector for their 3.7V Lithium polymer batteries and built in battery charging. The battery isn’t a requirement for using it, the board will run just fine straight from the micro USB connector or other external power sources. But, if you do have a battery, you can take it on the go, then plug in the USB to recharge. The Feather will automatically switch over to USB power when its available.

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.

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)

Comes fully assembled and tested, with the UF2 USB bootloader. We also toss in some header so you can solder it in and plug into a solderless breadboard.