[time-nuts] looking for low-power system for gps ntp timekeeping NANOSG20

[Hal Murray]

> It is a garmin 18x lvc.

That's pretty vanilla.  It really should work.  I won't be surprised if the 
NMEA is off by hundreds of ms and/or has 100 ms of wander, but the PPS should 
work.

Would you please try ntpd's NMEA driver, preferably from the latest ntp-dev
  http://support.ntp.org/bin/view/Main/SoftwareDownloads
The PPS code used by ntpd is different from gpsd.

If that doesn't work we should try to fix it.


>> rather than ntpd's NMEA driver?
> Oh for convenience. I need to patch ntpd to use linux
> pps (afaik) and on other systems I successfully run gpsd
> with ntpd (read: low jitter).

Were any of those systems ARM?

---------

One possibility is that the CPU is getting turned off when idle to save 
power.  If that includes the stuff normally used for timekeeping, things 
could get screwed up when it gets turned back on.  It has to reset the time, 
probably getting it from the RTC.

Can you measure the power when idle?  (kill off as much as possible, things 
like ntpd)  If that's suspiciously low that might be the problem.

Can you keep it busy?  If nothing else, "while true; do true; done"


-- 
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