Operating voltage: 3.3-5V Clock chip: high-precision clock chip DS3231 Programmable square-wave output IIC bus interface, the transmission speed of 400KHz @ working voltage of 5V Can be cascaded with other IIC device, 24C32 addresses can be shorted A0/A1/A2 modify default address is 0x57 Real time clock generator seconds, minutes, hours, day, date, month and year timing and provide valid until the year 2100 leap year compensation Pin instructions : 32KHz:32KHz output SQW:Active LOW Interrupt or Square wave output SCL:Serial Clock Input SDA:Serial Data I/O VCC:DC Power Pin GND:Ground If you use other board with this RTC module, you need check and change their SCL and SDA pins. Nano: SDA?A4, SCL?A5 MEGA: SDA?20, SCL?21 Leonardo: SDA?20, SCL?21 Wiring instructions: SCL ? A5 SDA ? A4 VCC ? 5Vv GND ? GND Package Included: 6 x DS3231 clock module See more

The RST pin is monitored as a pushbutton input for generating a microprocessor reset. A precision temperature-compensated voltage reference and comparator circuit monitors the status of VCC to detect power failures, provide a reset output. In addition, RST pin is monitored as generating a µP reset. The DS3231 RTC IC with communication over I2C Interface. DS3231 RTC IC is that it has integrated crystal oscillator and temperature sensor and hence you don’t have to connect an external crystal. DS3231 is available in the same footprint as the popular DS3231 RTC. The RTC maintains seconds, minutes, hours, day, date, month, and year information. DS3231 RTC module can work on either 3.3V or 5V.