I'm using the analog Pins of Arduino Mega to read voltage, current and power values. Next step is to save this information in a SD Card (done) and also send it to a webserver, with an ESP8266-01, via AT commands (also done).
Now i wanna save the timestamp of each readed value so i can analyse the data if the wi-fi signal is lost, without using any external clock.
My idea: ask a website for the time and receive a string with the date and hour like: Mon, 09/07/2018, 14:40. Any suggestion for this problem? I've tried to find similar problems but can't find any solutions.