METRO M0 Express

Adafruit METRO M0 Express is an upgrade from the original METRO 328 and features an ATSAMD21G18 ARM Cortex MO+ chip instead of the ATmega328. The ATSAMD21G18 ARM Cortex M0 processor is clocked at 48MHz and has 3.3V logic, the same as in the Arduino Zero. This chip has 256K of FLASH (8x more than the Atmega328) and 32K of RAM (16x as much). This chip comes with a built-in USB so it has USB-to-Serial program and debug capability with no need for an FTDI-like chip. CircuitPython is based on the open-source MicroPython that brings the popular Python language to microcontrollers. CircuitPython is a full-featured version of the popular Python programming language for use with circuitry and electronics. The METRO is powered with 7-9V polarity protected DC or the micro USB connector to any 5V USB source. The METRO will automagically switch between USB and DC.