I use NTP. I pull time from the RTC until I get a a sync from the internet - then I switch to the internet and I update the RTC whenever I get an update from the network. It all uses UTC, which is converted to local time for display.
On Wednesday, September 29, 2021 at 2:01:32 PM UTC-4 gregebert wrote: > I'm using network time that my Raspberry Pi re-acquires roughly every 20 > minutes, with a DS3232 for backup when the internet is down. I need to > tweak the software a bit more to automatically update the DS3232; right now > I have to use my debug utility to manually update it. But this does allow > me to see how much long-term drift there is. Here is an actual check from > today: > > INIT: RTC module = 09/29/21 08:52:56 > INFO: NTP sync acquired at 09/29/21 09:52:12 > > It's been about 6 months since I sync'd the time, and this particular > DS3232 RTC has gained 44 seconds. That's about 3PPM, which is pretty close > to the datasheet spec of 2PPM. I have not made any attempt to use the trim > register yet, but now that I have this data I might give that a shot. > > > > > On Wednesday, September 29, 2021 at 9:34:27 AM UTC-7 nixiebunny wrote: > >> My latest scope clock uses a DS3232 RTC chip for general timekeeping. >> This chip only keeps time to the nearest second, as far as the >> user-readable registers are concerned. >> I also have a USB port that can read the time from a GlobalSat GPS puck. >> This reports the time once a second through the Arduino TinyGPS library, >> with the age of the time in milliseconds (typically 250). This should let >> me compensate for the read delay by setting the tick (50/60Hz) counter in >> my local time variables. >> What do any of you time nuts do about displaying the time accurately, and >> making the RTC be reasonably accurate compared to the GPS? >> Do you discipline the RTC with GPS? Do you just ignore the RTC when GPS >> is available? Set the RTC occasionally? >> >> -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/75498a13-76c8-4c08-b7a6-c66e923443dan%40googlegroups.com.
