On Thursday, October 17, 2019 at 11:15:00 AM UTC-7, David VE3STI wrote: > I have used the RPi because it is a power miser, it is small and it is > cheap enough to be bought new and 'dedicated' to a single purpose. >
Yup. Most pi users do the same, as do people with similar tiny/low-power non-RTC systems (like me - I run on a Seagate Dockstar, which is essentially a stripped down PogoPlug). There have been MANY discussions about weewx/pi/etc. and databases needing accurate time here in the past. Almost too many to recount. But the short 'software' solution is: - disable anything that tries to keep track of the software time either periodically, or when you do an orderly shutdown - run ntpd or equivalent in your boot sequence if your system will be connected to an Internet time source - 'test' your system's powerout behavior. Every computer comes up at a predictable date+time when it is powered on, if you do not have a RTC. See what that value is. Note: systemd (grrrrrr) 'also' seems to have something like the user-space 'fake-hwclock' that is also in debian(ish) operating systems. You need to disable systemd helping too much (grrrrrr!). Again, do a few controlled tests. See what time is. Yank the power. See what date+time it boots to. Reboot the box. See what it does 'then' re: date+time. Basically baseline your system. Weewx shouldn't start up if the date+time of weewx.conf is newer than the system clock, if I remember the code correctly, so you should be safe from reboots. FWIW, I do 'not' have a RTC on my Dockstar nor do I have a UPS for several reasons. I 'do' have the battery in the Davis VP2 console however, so theoretically I should be able to run the console on battery there for a long long time. I only had one power out for more than a couple minutes in the last 10 years I've had this in place, we were down for about 2 days, but the datalogger stayed ok and weewx recovered just fine for me back then when power came back up. Of course your mileage might vary. RTC is good. RTC+UPS is better. All comes down to your budget etc. -- 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]. To view this discussion on the web visit https://groups.google.com/d/msgid/weewx-user/230e9226-adad-4a38-903f-f6fe48e17ed0%40googlegroups.com.
