I am suffering from no internet providings at the moment and it has brought up quite a few issues that had never entered my head before, one of which is anything that relies on fetching the time from the internet can be unreliable.
As the Cerbo is always on and supplied by the batteries which should practically never be so flat that the cerbo is not powered up, I would like to set up an ntp server on it for other devices on the same network to look to for the time.
Well, I’ve got a NUC on the LAN as well, running Debian. Would that be better than the Cerbo for an ntp server ?
OGPS
(Ed @ Off-Grid Power Systems - offgridps.com)
4
Most definitely. Keep your power system as simple as practical and think of it as critical infrastructure. General network services are better suited for another device.
If you only need relative time, a GPS (USB module) on a Cerbo provides milliseconds since midnight (UTC) into NR.
The dbus doc for the GPS service say it reads GPS data in NMEA0183 format, which might include time & date? Code appears to parse that all away to get the UTC mS data
So if I plug a Globalsat BU353-S4 into a usb socket on the Cerbo, it should work ?
Edit: Yes, looking around it seems like it has been tested with the Cerbo. Probably need to tell the Cerbo to get the time from it rather than the net. Best would be maybe to have the net time when available and swing over to GPS when no net.
You said you have a NUC – so plug the GPS module in there and use it via chrony (or ntpd/ntpsec) as a stratum-1 time source; that way, you can redistribute the time in your LAN, and it automatically falls back to sources from the Internet when GPS reception drops out.
If you care about milliseconds, you need a GPS module with PPS signal ($10 on aliexpress) and a way to interface that to your computer, which might be easier on a raspberry pi than a NUC. (If you really care, you distribute three of those raspberrys geographically )
Thanks. A few minutes accuracy is fine for me, it’s just to stop things getting stuck on 01:00 01/01/1970 and stuff when the internet goes off.
I was thinking the Cerbo because it hosts Node-red as well as it’s own OS plus it is practically never going to switch off. Then I can give the GPS time to the NUC and EVSE, but if it would be easier on the NUC then I will probably do that.
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