[Ovmsdev] Car lost GPRS connection notification

Pierre Uhl pi.uhl at bluewin.ch
Sat May 19 22:07:02 HKT 2012

At least it should be possible to switch off the feature. When parking at
home there is no GSM/GPRS coverage in my garage. I do not want to get

an alert every day after I parked my car.




Von: ovmsdev-bounces at lists.teslaclub.hk
[mailto:ovmsdev-bounces at lists.teslaclub.hk] Im Auftrag von Mark Webb-Johnson
Gesendet: Dienstag, 15. Mai 2012 07:15
An: OVMS Developers
Betreff: [Ovmsdev] Car lost GPRS connection notification



Rafael has suggested that we add a car-lost-gprs-connection notification to
the OVMS system. The idea being that when your car loses GPRS connection
(cellular coverage, fault, whatever), you get a notification to your app to
let you know. And, presumably, another notification should it come back.


*	It is common for a car to lose cellular connection for a minute or
so, then re-establish.
*	It is also reasonably common to lose connectivity when the GSM
signal is lost.
*	It does seem a nice idea, and not too hard to do.


The way it would work would be to have a threshold in the server. A
notification time, presumably in seconds.


1.	If a car disconnected (or 20 minute timeout was force disconnected),
we would put a record in a pending table, timestamped
2.	If the car connected, and the pending table has a record for that
car, we would just remove the record.
3.	If the car connected, and there was no pending table record for that
car, we would send a push notification for all apps on that car to tell them
that the car is connected.
4.	Periodically, we check the pending table and if any records have
timed out, we (a) send a push notification for all the apps on that car to
tell them that the car has disconnected, and (b) remove the record.


The result of this is that if the car disconnects for a short time, then
reconnects, no notification is raised. But, if the car disconnects for a
long time, you get a notification both when we find it has disconnected and
when we see it reconnect. This can all be done from the server, irrespective
of version of firmware in the car/apps.


The questions are: (a) what do people think, (b) what should a reasonable
timeout be, and (c) could this be _on_ for everyone.


Would anyone here _not_ want this?


I would suggest a reasonable timeout, to alert after, would be an hour or


It is easier to code this if it is universally on for everyone - we can just
have a single timeout in the server. If we want individual control, we'd
have to have a setting per-vehicle and provide the users a mechanism to
change that setting. That would be much more work.


Regards, Mark.


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