Arduino Mega 2560 R3 + RTC DS3231 excellent accuracy (60 months) ~ Česky ⁴ᴷ

Exact time was taken from NTP server 5 years ago. Backup RTC kept almost exact time. Not accurate time and difference was shown on the TFT display.

DS3231 Extremely Accurate I²C - real accuracy for 61 months (1860 days):
difference between RTC and NTP is circa 278 seconds, so accuracy is about 0,15 sec per day. It is much better than datasheet says!

DS3231 RTC module - 5V & 3.3V TTL logic, I²C interface

Datasheet says:
● Accuracy ±2ppm from 0°C to +40°C
● Accuracy ±3.5ppm from -40°C to +85°C
2ppm accuracy corresponds 63 seconds per year.
3.5ppm accuracy corresponds 111 seconds per year.

Performed by Actors:
Arduino Mega 2560 R3 + Ethernet Shield + RTC DS3231 + SPI TFT 1.8"

Source code:
Uncomment next line in source code if you want to update time in the RTC chip
//#define ENABLE_RTC_UPDATE

Purchased:

#arduino