See the Wiki section Time <https://github.com/weewx/weewx/wiki/Raspberry-Pi#time> about this issue.
-tk On Sat, Mar 9, 2019 at 11:50 AM Greg Troxel <[email protected]> wrote: > Thomas Keffer <[email protected]> writes: > > > Do you have a real-time clock? > > No. I knew I should, and had thought I had avoided the problems and > forgot about the issue. Or rather I think I have one someplace that I > haven't installed yet :-) > > I just checked and added some instrumentation. > > First, when NetBSD boots, it grabs the time from the filesystem, so the > time is behind, but definitely not 1970. Startup is not parallelized, > so things after ntpdate should have the right time. > > A recent reboot looked like > > Mar 9 13:20:32 wx ntpdate[276]: Can't find host 0.netbsd.pool.ntp.org: > hostname nor servname provided, or not known (8) > Mar 9 13:23:53 wx ntpdate[276]: step time server 204.9.54.119 offset > 173.216131 sec > > (not sure about that DNS, but other things were found). > > weewx is not started until ntpdate has run and ntpd is started. So > normally, weewx does not encounter bad times. > > However, I suspect that on restoration of power, there were some other > issues in my network which caused the weewx RPI3 to not get an IP > address, and thus ntpdate to time out, and therefore weewx to start with > time that is based on the crash time. So probably still ahead of the > last time it ran, but sort of a few minutes into the failure, not the > restoration time plus a bit like it should be. > > So, I wonder if weewx was changing the Davis console clock, based on the > computer being 1.25h slow. > > To avoid this in the future, I wrote a script to delay weewx start until > ntpd is happy. On a reboot of the RPI with everything else stably > powered, this resulted in a delay of 3m20s. The time was already ok > (from ntpdate), but that's not reliable. (I think the script depends > only on ntpd/etc. and things specified by POSIX.) > > I wonder about weewx being able to check ntp sync, and only being > willing to adjust the console if ntp reports that it is synced. In a > way the console is a RTC. > > Thanks again for paying attention to my question. > > > #!/bin/sh > > date > ntpq -c sysinfo > ntpq -pn > > while sleep 5; do > trace=`ntptrace -n | head -1` > stratum=`echo $trace | sed -e 's/.*stratum \([0-9]*\),.*/\1/'` > if [ "$stratum" -lt 16 ]; then > echo OK $trace > break; > fi > echo UNSYNC $trace > done > > date > ntpq -c sysinfo > ntpq -pn > > bin/weewxd weewx.conf > > -- You received this message because you are subscribed to the Google Groups "weewx-user" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
