[time-nuts] Holdover, RTC for Pi as NTP GPS source
MLewis
mlewis000 at rogers.com
Wed Nov 1 19:21:43 EDT 2017
Is this a workable or worthwhile strategy?:
- RTC providing date & time to second to system on boot
- RTC frequency output driving a counter/divider to produce PPS
- GPS module providing UTC PPS
- GPS module's secondary PPS disciplining the RTC-counter-divider PPS by
resetting the RTC's counter/divider (I'm assuming there's one that will
rest fast enough to sync; I've never looked into these...)
If GPS PPS is lost, then the RTC counter/divider is producing a recently
disciplined PPS.
Valid or invalid?
And the DS3231 has:
- a 32K output, and
- an Active-Low-Interrupt/SQW output that can be set to PPS.
It's unclear to me how to sync the DS3231 PPS to the GPS PPS, or if that
can be done.
Thanks,
Michael
More information about the time-nuts
mailing list