Hi @anon57585045
I'm doing a comparative study between 3 "clocks".
It's a sketch running on ES8266.
The project has an RTC module with DS3231, a routine in ESP8266 using the ticker.h library and access to NTP, (Network Time Protocol) (Clock on the WEB).
In the DS3231 datashhet, (which has the internal crystal and thermally compensated), the manufacturer informs that the deviation is:
• Accuracy ±2ppm from 0°C to +40°C
• Accuracy ±3.5ppm from -40°C to +85°C
The temperature where I live and run the test varies from 28°C to 32°C.
The sketch has been running for 20 days.
The results were as follows.
Deviation from:
0 seconds between NTP and routine on ESP8266; 0 PPM so far;
13 seconds between NTP and RTC with DS3231; 7.8 PPM so far;
RTC with DS3231 is 13 seconds ahead of NTP.
Advance 1 second every 36 hours.
RV mineirin