I’m here to ask you about you about the accuracy of the Photon’s RTC that you’re using to keep the time on the clocks that are not connected to the internet. Do you have an idea now at how much time drift you get using Photons built-in RTC?
I’ve been testing the DS3231 RTC which is supposed to be one of the more accurate options and it’s off by 2 mins and 20 seconds after a little less than 1 year. I’m tracking the suns position in the sky and accurate time is needed to do this.
@RWB Hello! Many thanks, I am pleased you like our clock!
The accuracy of Photon’s RTC is not good, far from DS3231. In my case, the Photon drifts around 1-2 seconds per day when the clock is running without connection to internet. I am not actually sure if the time is maintained by RTC or caculated by the processor when the module is running - the internal RTC might be used only when Photon is not powered (and RTC is supplied from backup battery). I tried to explore RTC calibration features which should improve this significantly, but I didnt find satisfactory information on this topic (too many contradictory information) and because almost all customers use the clock online (time is in sync), I assigned this task low priority. I will have to solve the calibration one day as we are working on several projects with Swiss watch/clockmakers and the clocks are supposed to run also offline. If you find something, please let me know.
You can find some more info here: https://community.particle.io/t/internal-rtc-calibration
If there is anyone who is capable of setting up the calibration functions on Photon, I am willing to pay for his services.
I think I may just have to spend a little more money and just use a GPS module for accurate time. The RTC was an attempt to avoid the use of a GPS sensor.
Good luck with the Nixie Clocks! When I reach some financial goals I plan on getting your tubes and PCB.
