DS1307 is a real-time chip of DALLAS company, which adopt I2C protocol to communicate with SCM, and there was this kind interface on Arduino, therefore is very convenient to link with each other. DS1307 have a programmable waveforms output, it can be used to drive LED lights or trigger a certain event as a break-off, but be careful when you use it to take some kind of high power module. We design the real clock module to pin out the I2C interface of Ds1307 and programmable waveforms output interface SQW are connected, but usually, we will only use the I2C interface to realize basic set the clock/read function. Note, this module must be installed on the battery can work normally. The battery is button batteries (type CR2032 will be better), the positive upward:

Features

1. Real-time clock counts seconds, minutes, hours, date, month, day, year, and leap year to 2100 
2. 56-bytes general-purpose NV RAM 
3. Accuracy > 2 minutes/month at 25oC 
4. Automatic power management circuitry 
5. 2-wire serial interface 
6. The programmable square wave output signal 
7. Uses <300nA in backup mode with oscillator running