This is shield for WeMos D1 mini / PRO- RTC DS1307 Shield  (Real Time Clock) + battery  with pin-headers set RobotDyn  WeMos D1 mini / PRO is not included .

you can use it to add time management to your project with days week years functionality so if you are looking for time management  without internet access this is what you need .

and now let's give some info about the DS1307 chip :

eal time clocks (RTC), as the name recommends are clock modules. The DS1307 real time clock (RTC) IC is an 8 pin device using an I2C interface. The DS1307 is a low-power clock/calendar with 56 bytes of battery backup SRAM. The clock/calendar provides seconds, minutes, hours, day, date, month and year qualified data. The end date of each month is automatically adjusted, especially for months with less than 31 days.

They are available as integrated circuits (ICs) and supervise timing like a clock and also operate date like a calendar. The main advantage of RTC is that they have an arrangement of battery backup which keeps the clock/calendar running even if there is power failure. An exceptionally little current is required for keeping the RTC animated. We can find these RTCs in many applications like embedded systems and computer mother boards, etc. In this article we are going to see about one of the real time clock (RTC), i.e. DS1307.

Features:

• Programmable square wave output signal
• Automatic power-fail detect and switch circuitry
• Consumes less than 500nA in battery backup mode with oscillator running
• Available in 8-pin DIP or SOIC
• Underwriters Laboratory (UL) recognized
• Real-time clock (RTC) counts seconds, minutes, hours, date of the month, month, day of the week, and year with leap-year compensation valid up to 2100
• 56-byte non-volatile RAM for data storage
• Two-wire interface (I2C)