So there’s a nice project for the mathematically inclined. My ESP boards get the time (summer time and location corrected) via MQTT where that’s worked out on a more powerful Raspberry Pi. They also get dusk and dawn times.
As it is possible on the ESP to get the time via NTP, and it is easy to add the regional offset, all that is missing is summer/winter time correction and dusk and dawn times in a stand-alone environment. I found one piece of code which looked like it might do the job but it would not compile as all the various floating point libraries such as sin/cosine etc. etc. are all missing.
Is there another way to get local, summer adjusted time and date along with lighting up and dawn times, from a server without having to do lots of maths locally. Clearly one could write something on a server somewhere in PHP to do the job – but that might be re-inventing the wheel?