This is what is known as a Real Time Clock (RTC) module and can be used with any Arduino so that it can tell time. The Arduino does not have a RTC on board and therefore can not tell time for an extended period of time with any accuracy. When the Arduino does tell time it uses an internal counter to calculate an amount of elapsed time, this is inaccurate, limited (the clock can only count so high), cannot be related to the real time (i.e. the time on your watch), and is reset every time the Arduino is reset. The RTC allows you to create projects that are time dependent such as automating your coffee maker to make coffee at a set time of the day. It can also be used to create a clock in any of your Arduino projects such as an Arduino with an LCD display showing the values of various sensors.
This RTC board also includes an ambient temperature sensor with a sensing range from 0-40°C
Information on how to implement this RTC can be found here on the Arduino.cc website.
This RTC has been successfully tested with 3.3vdc microcontrollers.
Uses the DS3231 high-precision real-time clock chip (IIC interface rate 400KHz)
Also incorporates a AT24Cxx IIC interface with EEPROM memory interface through the header pins or solder pads
Chip integrated internal precision 32.768KHz TCXO crystal with an annual error of about 1 minute
Chip integrated temperature sensor (0-40°C), accuracy 3°C, and a resolution of 0.5°C can be used to measure the ambient temperature
CR927 non-rechargeable 3V battery is included on the board to ensure the real time clock is alaways opperating
The power supply terminal is protected by a anti-reverse diode and reverse power burn circuit
Leads SQW / INT and 32KHz square wave output interface, can output different frequency square wave, and output an alarm interrupt
Can be cascaded to other the IIC devices using the header pins
Dimensions: Depth 20mm, Height 34mm, Width 15mm, Weight 3.2g