WIFI D1 mini - Data logger shield: RTC DS1307 with battery MicroSD
The set includes:
Data Logger and RTC Shield for WeMos / WiFi D1 mini PRO. This shield allows you to store data on an SD card. The included RTC (Real Time Clock) can be used to add a timestamp, so that you know the exact time of each record! The coin cell backup battery keeps the real time clock going even when the power is disconnected. The real-time clock has reverse polarity protection.