Adafruit Feather M0 Express - Designed for CircuitPython - ATSAMD21 Cortex M0

ATSAMD21G18 ARM Cortex M0+ processor with 256K Flash and 32K RAM CircuitPython is still in beta Measures 2.0" x 0.9" x 0.28" (51mm x 23mm x 8mm) without headers soldered in. 5 grams 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) Comes fully assembled and tested, with a USB bootloader that lets you quickly use it with the Arduino IDE or for loading CircuitPython. We also toss in some header so you can solder it in and plug into a solderless breadboard.