This a custom designed module for the DS1307 Real Time Clock. The module comes fully assembled and pre-programmed with the current time (ok, so it’s * our current time - *MST). The included Lithium coin cell battery (CR1225 41mAh) will run the module for a minimum of 9 years (17 years typical) without external 5V power. The DS1307 RTC is accessed via the I2C protocol. We’ve written a test-bed to program the modules. This test-bed code should give you some insight on how to interface the module to any microcontroller using our example software I2C and BCD routines.