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 neonixie-l+unsubscr...@googlegroups.com. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/082b2c9b-854c-4ea2-bab7-0a7227f2b451n%40googlegroups.com.
