Adafruit Trinket M0 Development Board
Adafruit Trinket M0 Development Board is a tiny easy to use microcontroller board that is small enough to fit into any project without hesitation. This development board retains the same size (27mm x 15.3mm x 2.75mm / 1.07" x 0.6" x 0.1"), form-factor, and pinout as classic Trinket. The Trinket M0 is built around the Atmel ATSAMD21E18 Cortex M0+ powerhouse and can be used with Arduino IDE or Adafruit's CircuitPython. The Trinket M0 board is equipped with main.py for coding using Python in any text editor of the user's choice. This eliminates the need for any software installs, IDE, or compilers.

The ATSAMD21E18 32-bit Cortex M0+ feature 256KB flash, 32KB RAM, and 48MHz speedups. The native USB of this Trinket M0 board is supported by every OS and can be used in Arduino or CircuitPython as USB serial console. This development board offers built-in LEDs and five General Purpose IO (GPIO) pins that are not shared with USB for multipurpose usage. The Trinket M0 board is designed with native hardware SPI, I2C, and serial on two pads for true hardware support.

Features
Programmable using Arduino IDE or CircuitPython
5 General Purpose I/O (GPIO) pins:
All five pins with digital input/output for internally connected pull-ups or pulldowns
Three pins can be used for 12-bit analog input
Native true hardware support for SPI, I2C, and serial
Two high-speed PWM outputs - for servos or LEDs etc
Same Reset switch for starting your project code over
Built-in LEDs
RGB DotStar
Red #13
ON
Native USB supported by every OS
Power with either USB or external output (such as a battery)
Supports automatic switchover
Specifications
Super small form factor
Dimensions: 27mm x 15.3mm x 2.75mm / 1.07" x 0.6" x 0.1"
Height with MicroUSB: 3.5mm / 0.14"
Powered by ATSAMD21E18 32-bit Cortex M0+ (48MHz processor)
32KB RAM
256KB Flash
3VO output pad can provide up to 500mA at a steady 3.3V