Product Material: Electronic material Size: 38mm (length) * 22mm (width) * 14mm (height) Working voltage: 3.3--5.5V Clock chip: DS3231 Clock accuracy: In the range of 0-40℃, the accuracy is 2ppm and the annual error is about 1 minute With 2 calendar alarm clocks Programmable square wave output Real-time clock generates seconds, Minutes, hours, day of the week, date, month and year and provides leap year compensation with a validity period of up to 2100 Built-in temperature sensor in the chip with an accuracy of 3℃ Memory chip: AT24C32 (storage capacity 32K) IIC bus interface, the maximum transmission speed is 400KHz (at a working voltage of 5V) Other IIC devices can be cascaded, the 24C32 address can be changed by short-circuiting A0/A1/A2, the default address is 0x57 With CR2032 battery Wiring instructions (take Arduino uno r3 as an example): SCL A5 SDA A4 VCC 5V GND GND Packing method: individual antistatic packaging Quantity: 3 Piece Set Package Contents: 3 * IIC Modules 1. DS3231 AT24C32 is used as a real-time clock chip that keeps time even when the main power is off (using a battery). 2. Functionality including seconds, minutes, hours, day, date, month and year, with leap year compensation up to the year 2100. 3. DS3231 memory chips - AT24C32, I2C real-time clock (RTC), with an integrated temperature-compensated crystal oscillator (TCXO) and crystal. 4. Provides programmable time of day alarms and a calendar can be set to square wave output. Address and data are transmitted serially over a bi-directional I2C bus. 5. A precise temperature-compensated voltage reference and comparator circuit monitors the status of VCC to detect power failures and provide a reset output. It also monitors that the RST pin generates a P reset.