The DS1307 Real Time Clock module is a low-power, full binary-coded decimal (BCD) clock/calendar plus 56 bytes of NV SRAM. It allows your microcontroller to keep track of time even if it is reprogrammed or power is lost. Address and data are transferred serially through an I2C, bidirectional bus.

This Real Time Clock module is based on the clock chip DS1307 that provides seconds, minutes, hours, day, date, month, and year information for your project. The end of the month date is automatically adjusted for months with fewer than 31 days, including corrections for leap year. The clock operates in either the 24-hour or 12-hour format with AM/PM indicator. The DS1307 has a built-in power sense circuit that detects power failures and automatically switches to the backup supply. The timekeeping operation continues while the part operates from the backup supply.

Note: The DS1307 is not a high-precision device and may lose or gain up to 2 seconds per day.