“While looking for the accuracy of the ESP32 RTC, the idea came up to measure it and continue working with the data.
The ESP32 should get the time from a time server via WiFi and compare it with the RTC of the ESP. The times and the time difference should be shown on the display. Between the measurements, the ESP should go into deep sleep mode. In addition, the data should be saved on a web server.
A Raspberry Pi with Apache and PHP serves as the web server.
The SH1106 display is connected via I2C, with GPIO22 on the ESP with SCK on the Display (yellow line) and GPIO21 with SDA (green line). Ground with ground (black line) and 3.3V with VDD (red wire). The 10k Ohm resitor comes from 3.3v and go to GPIO15 (white line) and the push button. Ground go to push button (black line).
In this Sketch you have to set your Wlan-Name and Wlan-Password, your Router or Timeserver IP, your URL of the Webside, the Messurement Cycle is 5 min (must between 2 and 59 min).
The Timezone is GMT+1 with Daylightsavingtime, you may have to change it.”