Seeed Studio Real Time Clock (RTC) with DS1307 and Battery Backup for Raspberry Pi

The Pi RTC is based on the clock chip DS1307, it can provide a real-time clock(RTC) for raspberry pi via the I2C interface. Real-time clock of this module counts seconds,minutes, hours, date of the month,month, day of the week, and year with leap-year compensation valid up to 2100. The clock operates in either the 24-hour or 12-hour format with AM/PM indicator. If you want to keep this module timing when the Raspberry Pi is powered off, you need to put a 3-Volt CR1225 lithium cell in the battery-holder.

Support Raspberry Pi 2/ 3 B/B+ Zero
Support seconds,minutes,hours,day of week,month, year
Support 24-hour or 12-hour format with AM/PM indicator
56-byte, battery-backed, non-volatile (NV) RAM for data storage
Programmable square wave output signal
Automatic power-fail detect and switch circuitry
Applications
Applications need Real Time on Raspberry.