Adafruit 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)
Works great with an Arduino using our RTC library or with a Raspberry Pi (or similar single board linux computer)
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. We recommend you purchase a coin cell battery to use with this product.
The DS1307 is simple and inexpensive but not a high precision device. It may lose or gain up to 2 seconds a day.
Mounting holes are 2.2mm(0.086in) diameter, 25mm(0.98in) apart
This board/chip uses I2C 7-bit address 0x68