The Seeed Pi RTC is based on the DS1307 clock chip and can provide a real-time clock (RTC) for your Raspberry Pi via the I2C interface. The 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. Features Supports all models of Raspberry Pi Model B or A Supports seconds, minutes, hours, day of week, month, year Supports 24-hour or 12-hour format with AM/PM indicator 56-byte, battery-backed, nonvolatile (NV) RAM for data storage Programmable squarewave output signal Automatic power-fail detect and switch circuitry Product number: Seeed103030277 Pinout Specifications Dimensions 30mm x23mm x15mm Weight 13.2g Battery CR1225 (not included) Package Contents 1x Pi RTC (DS1307) 1x 2-pin header Battery NOT included Resources Product Wiki Seeed Pi RTC Library DS1307 Datasheet Eagle Files