Adafruit 3296 - DS1307 Real Time Clock Assembled Breakout Board

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. The DS1307 is the most popular RTC - but it requires 5V power to work (although we've used it with 5V power and 3.3V logic successfully) PCB & header are included Plugs into any breadboard, or you can use wires Two mounting holes Will keep time for 5 years or more Note: This product does not come with a CR1220 coin cell battery.  The DS1307 is simple and inexpensive but not a high precision device. It may lose or gain up to 2 seconds a day.  Adafruit part: 3296