Adafruit Feather M0 Basic Proto

Overview

The Adafruit Feather M0 Basic Proto is a 32-bit ARM Cortex-M0+ development board in the Feather form factor, built around the Microchip ATSAMD21G18 running at 48 MHz. It represents a significant step up from AVR-based Feathers, offering 256KB of flash, 32KB of RAM, 12-bit ADC/DAC, and native USB support — all in a thin, lightweight 51 × 23 mm package at just 4.6 grams.

The ATSAMD21 handles USB natively, enabling the board to appear as a USB disk drive for drag-and-drop CircuitPython firmware uploads. It also supports Arduino IDE via the Arduino SAMD board package, providing PWM on all pins, six 12-bit analog inputs, one 10-bit DAC output, and standard Serial, I2C, and SPI interfaces. A 32.768 kHz RTC crystal is included for timekeeping applications.

An integrated 100mA LiPoly charger manages battery charging when USB power is present, with automatic switchover between battery and USB. The 3.3V regulator provides 500mA peak output. A small prototyping area with through-holes is included on the PCB for minor circuit additions.

As the first Feather to support CircuitPython, the M0 Basic Proto established the SAMD21 as a core platform across dozens of Feather variants and FeatherWing accessories. Its combination of 32-bit performance, USB versatility, and compact size makes it suitable for data logging, audio, USB instruments, and battery-powered sensor nodes.