The ADAFRUIT INDUSTRIES Feather M0 basic proto is a comprehensive product with all the basic features shared by the Feather M0 range along with a small prototyping area. In simple projects that require you to attach a button or sensor, you could skip on a breadboard and wire it directly on the board. The Feather M0 is a range of development boards from Adafruit. It is powered by the Atmel ATSAMD21G18 ARM Cortex M0 processor clocked at 48MHz with 3.3V logic. This board features the same chip as is in the Arduino Zero (RS 883-7383). It has 256K of flash (8x more than the Feather 32u4 range) and 32K of RAM (16x). The Feather M0 is designed for low power, portable projects. This chip has built-in USB so it has USB-to-serial programming and debugs capability so no need for an FTDI-like chip. The product is fully assembled and tested, with a USB bootloader that lets you quickly use it with the Arduino IDE.
51 x 23 x 8 mm/2.0in x 0.9in x 0.28in without headers
4.6g
Atmel ATSAMD21G18 @ 48MHz with 3.3V logic/power
256 KB flash and 32KB RAM (No EEPROM)
32.768kHz crystal for clock generation and RTC
3.3V regulator with 500mA peak current output
USB native support comes with USB bootloader and serial port debugging
20 GPIO pins
Hardware Serial, hardware I²C, hardware SPI support
PWM outputs on all pins
6 x 12-bit analogue inputs
1 x 10-bit analogue output (DAC)
Built-in 100 mA LiPo charger with charging status indicator LED
Pin #13 red LED for general purpose blinking
Power/enable pin
4 mounting holes
Reset button

Dedicated connector for 3.7 V lithium batteries
Built-in battery charging circuit enables you can use to measure and monitor battery levels
Process type is MCU