[RFC] Unmanaged GPS setup / location source

Dan Williams dcbw at redhat.com
Fri Jun 27 08:45:44 PDT 2014

On Fri, 2014-06-27 at 10:51 +0200, Aleksander Morgado wrote:
> Hey,
> I've been asked whether it would make sense to allow having
> ModemManager control the status of the GPS module in a device, *but*
> leaving the tty where the NMEA traces are dumped untouched. This would
> allow to integrate with other standard GPS applications which read
> from a tty, while leaving MM the control over when to enable/disable
> the GPS module.
> Any comments on this?

I haven't looked at the code yet, but the approach seems OK.

> I have a draft implementation (mmcli commands not yet done) already in
> the 'aleksander/gps-unmanaged' branch in upstream git, where I just
> define a new MM_MODEM_LOCATION_SOURCE_GPS_UNMANAGED source. When this
> source is enabled, GPS module is started but the GPS tty is not used.
> Of course, the implementation also forbids trying to enable unmanaged
> and raw/nmea GPS at the same time. Also, currently only done for
> Option/HSO (the only plugin which does GPS over a tty for now). I may
> add GPS support for Cinterion one of these days as well.

Gobi! :)  The fun thing here is that you have to open the port and run
$GPSSTART or something like that, then it starts spewing NMEA, and to
stop it you  have to re-grab the port and run $GPSEND.  I guess that
would be fun if the port is still locked by the consumer.

Also, I think the Ericsson devices do raw NMEA to a TTY too.


More information about the ModemManager-devel mailing list