This is a great battery-backed real time clock (RTC) that allows your microcontroller project to keep track of time even if it is reprogrammed, or if the power is lost. Perfect for datalogging, clock-building, time stamping, timers and alarms, etc. Equipped with PCF8523 RTC - it can run from 3.3V or 5V power & logic! https://elecena.pl/product/17501461/adafruit-pcf8523-real-time-clock-assembled-breakout-board 2021-04-07 https://elecena.pl/product/17501461/adafruit-pcf8523-real-time-clock-assembled-breakout-board 2022-03-26