This is DS1307 RTC Real Time Clock Module Without Battery. It contains a DS1307 real-time clock IC with a backup battery. It’s one of the easiest to use RTCs out there, with Arduino and other libraries or simply use I2C commands to set and retrieve the time and date. Includes a lithium coin cell battery which should be good for four years at least.

Along with the DS1307 real-time clock, the module also has an Atmel 24C32 EEPROM chip which is handy for storing data without worrying about power loss. There is also space on the board to solder your own DS18B20 temperature sensor.

This battery-powered clock allows you to keep a reasonably accurate time even when your Arduino is powered off.  It is very useful in data logging and other time-sensitive applications. The device uses I2C to communicate with your Arduino.

Note: Battery is not included in the package, you need to buy it separately.

Features :

1. Two-wire I2C interface
2. Hour: Minutes: Seconds AM/PM
3. Leap year compensation
4. Accurate calendar up to the year 2100
5. Consumes Less than 500nA
6. 1Hz output pin
7. 56 Bytes of Non-volatile memory available to the user
8. 4KB of serial electrically erasable and programmable read-only memory (EEPROM)
9. Embed DS18B20 temperature sensor interface with the pull-up resistor.

Package Includes :

1 x DS1307 RTC Real Time Clock Module Without Battery