The DS3231 is a low-cost, high-precision I2C real-time clock (RTC) with an integrated temperature-compensated crystal oscillator (TCXO) and crystal.

Specifications

• Size: 38mm (length) * 22mm (width) * 14mm (height)
• Working voltage: 3.3--5.5V
• Clock chip: high-precision clock chip DS3231
• Clock accuracy :0-40℃ range, accuracy 2ppm, annual error 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 valid until 2100
• The chip has its own temperature sensor with an accuracy of ±3℃
• Memory chip: AT24C32 (storage capacity 32K)
• IIC bus interface, maximum transmission speed 400KHz (when the operating voltage is 5V )
• Can be cascaded with other IIC devices. The 24C32 address can be modified by short-circuiting A0/A1/A2. The default address is 0x57

wiring instructions (taking uno r3 as an example):
SCL→A5
SDA→A4
VCC→5V
GND→GND