schufti wrote:as the used crystal is no precision part and heavily dependant on teperature, there is nothing much to improve. In average it wakes ~3% early ...
I think that: when the esp8266 is in deep sleep mode, the internal time is managed by a counter. The idea would be to compare the incremental value of the counter with an incremental real-time value before sleeping the esp8266. With these values, the counter and the real, would get a factor that would allow me to correct the time