1、Use Maxim DS1307 chip 2、Automatic Power-Fail Detect and Switch Circuitry 3、Can be operated by a shell 4、Set a serial port connector 5、Programmable square-wave output signal Description: The RTC module is specifically designed for Raspberry Pi. It communicated with for Raspberry Pi through I2C bus. Features: Use Maxim DS1307 chip Can be operated by a shell Set a serial port connector Programmable square-wave output signal Automatic Power-Fail Detect and Switch Circuitry Programmable Square-Wave Output Signal Port: Raspberry Pi B module 2X13 connection port Raspberry Pi A+/B+/2 module 2X13 connection port 2*5pin 2.54mm connector Specifications: Accuracy: ±2ppm from 0°C to +40°C Battery Backup Input for Continuous Time keeping Real-Time Clock Counts Seconds, Minutes,Hours, Day, Date, Month, and Year with Leap Year Compensation Valid Up to 2100 Work Temperature: 0°C to +70°C Typical Application: Smart home Utility Power Meters Telematics Color: Red Size: Approx. 2.65 * 2.27 cm / 1.04 * 0.89 in Package Weight: About 5g Package Included: 1x RTC Module for Raspberry Pi (Not including battery.)