Real Time Clock (DS3231)
Product Description
Specifications:
Size: 38mm x 22mm x 14mm
Operating voltage: 3.3 – 5.5V
Clock chip: DS3231
Clock accuracy: 0-40°C, accuracy of 2ppm, ±1minyear
2 calendar alarms
Programmable square wave output
The real-time clock saves seconds, minutes, hours, week, date, month and year, and provides leap year correction.
12 and 24-hour format with AM/PM indication.
Integrated temperature sensor, ±3°C
On-board Memory: AT24C32 (Storage capacity of 32K)
I2C bus interface, the maximum transmission speed of 400KHz (operating voltage of 5V)
Default I2C address is 0x57
A0-A2 can be modified for additional I2C addresses.
CR2032 battery holder with backup battery
Links
https://learn.adafruit.com/adafruit-ds3231-precision-rtc-breakout/overview
http://www.instructables.com/id/Real-time-clock-using-DS3231-EASY/
http://www.instructables.com/id/Arduino-DS3231-RTC-Clock/