Features: The DS3231 is a low-cost, high-precision I2C real-time clock (RTC) with an integrated thermo-compensated crystal oscillator (TCXO) and crystal. The device contains a battery input that maintains a timing when the main power supply is disconnected. The integrated crystal oscillator improves the longevity of the device and reduces the number of components in the production line. The DS3231 is available in both commercial and industrial grade temperature ranges in a 16-pin 300mil SO package.RTC stores second, minute, hour, day, date, month, and year information. For months with fewer than 31 days, the month end date will be automatically adjusted, including corrections for leap years. The working format of the clock can be 24 hours or 12 hours with /AM/PM indication. Provides two configurable calendar alarms and one configurable square wave output. Address and data are transmitted in serial via I2C bidirectional bus.1. Size :38mm(length)*22mm(width)*14mm(height) 2. Weight :8g 3. Working voltage: 3.3-5.5V 4. Clock chip: high precision clock chip DS3231 5. Clock accuracy: within the range of 0-40 degree C, the accuracy is 2ppm, and the annual error is about 1 minute 6. Bring 2 calendar alarms 7. Programmable square wave output 8. The real-time clock generates seconds, minutes, hours, days, days, months, and years, and provides leap year compensation valid until 2100 9. The temperature sensor inside the chip has an accuracy of +-3C10. Memory chip :AT24C32(storage capacity 32K) 11. IIC bus interface, transmission speed 400KHz(operating voltage is 5V) 12. Other IIC devices can be cascaded. The 24C32 address can be changed by short circuit A0/A1/A2. The default address is 0x57Wiring instructions (using Arduino uno r3 as an example): SCL to A5 SDA to A4 VCC to 5VGND to GNDPackage included:5Pcs DS3231 AT24C32 IIC RTC Clock Module High Precision Real Time Clock Sensor Storage Module