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. This FeatherWing will make it real easy to add datalogging to any of our existing Feathers. You get both an I2C real time clock (PCF8523) with 32KHz crystal and battery backup, and a microSD socket that connects to the SPI port pins (+ extra pin for CS). A CR1220 coin cell is required to use the RTC battery-backup capabilities! https://elecena.pl/product/18507246/2922-development-boards-adalogger-featherwing-rtc-sd-addon 2021-05-18 https://elecena.pl/product/18507246/2922-development-boards-adalogger-featherwing-rtc-sd-addon 2021-06-18 https://elecena.pl/product/18507246/2922-development-boards-adalogger-featherwing-rtc-sd-addon 2022-05-03 https://elecena.pl/product/18507246/2922-development-boards-adalogger-featherwing-rtc-sd-addon 2022-09-29 https://elecena.pl/product/18507246/2922-development-boards-adalogger-featherwing-rtc-sd-addon 2022-10-16 https://elecena.pl/product/18507246/2922-development-boards-adalogger-featherwing-rtc-sd-addon 2023-04-29 https://elecena.pl/product/18507246/2922-development-boards-adalogger-featherwing-rtc-sd-addon 2025-04-19 https://elecena.pl/product/18507246/2922-development-boards-adalogger-featherwing-rtc-sd-addon 2026-02-20