LoPy - getting datetime after power interrupt
When having a (battery) power interrupt one can possibly use a cheap GPS module connected to the LoPy to get the correct datetime (and enter in the RTC) when power is again available. Is/are there other ways to get the datetime after a power interrupt: e.g. is it possible to get the datetime from the concentrator/gateway?
@robmarkcole choices I see other than from GPS are
use a real battery backed up RTC (maybe via i2c https://www.sparkfun.com/products/12708).
get the time from network on startup.
obviously NTP works with Cat-M1 and Wifi if you have an internet connection.
It appears you could send date/time via downlink on sigfox, but due to rate limitations you would probably need to explicitly request time on boot.
Lorawan - you would need to provide a time service. It doesn't appear to be in the protocol spec, and traversal time would mean time is a bit wrong if you hop through nodes.
Option 1 would probably be the best option in my opinion. Works without a network if datetime/set correctly initially.