This module is an RTc module specifically designed for Raspberry Pi. The module communicates with Raspberry pi via the 12cprotocol. The on-board Ds1307 clock chip and a 1220 button battery ensure that the Raspberry pi can stil remember the timeeven after power loss. A serial port is reserved for convenient online debugging in TTL mode. t has a compact size but providessignificant power. One battery can record for approximately 3 vears.