Grove - DS1307 RTC (Real-Time Clock)

The Grove - DS1307 RTC is based on the clock chip DS1307 and supports I2C communication! It uses a Lithium cell battery (CR1225). We choose to use the RTC based on DS1307 as it is low cost and also very energy efficient. It can run for years on a very small coin cell. The clock/calendar provides seconds, minutes, hours, day, date, month, and year. The end-of-the-month date is automatically adjusted for months with fewer than 31 days, including corrections for leap years. The clock operates in either the 24-hour or 12-hour format with an AM/PM indicator. And it is valid up to 2100. In order to gain robust performance, you must put a 3-Volt CR1225 lithium cell in the battery-holder. The DS1307 has a built-in power sense circuit that detects power failures and automatically switches to the battery supply. If you use primary power only, the module may not work normally, because the crystal may not oscillate.