The Adafruit Feather are a complete line of development boards from Adafruit that are both standalone and stackable. They're able to be powered by lipo batteries for on-the-go use or by their micro-USB plugs for stationary projects. Feathers are flexible, portable, and as light as their namesake. At the Feather M0's heart is an ATSAMD21G18 ARM Cortex M0 processor, clocked at 48 MHz and at 3.3V logic. This chip has a whopping 256K of FLASH (8x more than the Atmega328 or 32u4) and 32K of RAM (16x as much)! This chip comes with built in USB so it has USB-to-Serial program & debug capability built in with no need for an FTDI-like chip. https://elecena.pl/product/18331829/2772-development-boards-adafruit-feather-m0-basic-proto 2021-05-05 https://elecena.pl/product/18331829/2772-development-boards-adafruit-feather-m0-basic-proto 2021-10-27 https://elecena.pl/product/18331829/2772-development-boards-adafruit-feather-m0-basic-proto 2022-06-15 https://elecena.pl/product/18331829/2772-development-boards-adafruit-feather-m0-basic-proto 2022-10-31 https://elecena.pl/product/18331829/2772-development-boards-adafruit-feather-m0-basic-proto 2022-11-17 https://elecena.pl/product/18331829/2772-development-boards-adafruit-feather-m0-basic-proto 2024-07-23 https://elecena.pl/product/18331829/2772-development-boards-adafruit-feather-m0-basic-proto 2025-04-07