Re: Memo mapper cannot connect to GPSD server?

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Hi!

On Thu, Apr 10, 2008 at 11:53:22AM -0600, Mark wrote:
> I'm confused; does Maemo Mapper use gpsd, just not through DBus?

Maemo Mapper can use gpsd, but normally gpsd is not running (to save
system resources, I assume).  The dbus bit is just a guess; the only
documentation I could find on maemo.org refers to two system libraries,
libgpsbt and libgpsmgr.  These libraries can start the gpsd for you on
request, but Maemo Mapper doesn't use them when you choose the GPSD
option.  As far as I understand; I haven't actually inspected the source
code.

> Maps
> and Maemo Mapper seem to get along fine running simultaneously

Right, because Maps tells the OS to start gpsd and then Maemo Mapper can
connect to it.

OTOH if you don't have Maps running, you can't use Maemo Mapper with
gpsd at all.  I tried.  Even if you trigger the GPSD by going into the
Control Panel's GPS applet and asking it to refresh your location, Maemo
Mapper only works for about 30 seconds until gpsd times out, notices
there aren't any apps asking for it via the Nokia-approved libraries,
and exits, making Maemo Mapper lose the connection.

> - is
> that possible with a direct Bluetooth connection?

Yes, if you choose the Bluetooth option in Maemo Mapper with an empty BT
address (which means "use the internal GPS" on a N810), then you can
have both MM and Maps running at the same time.

AFAIU, the empty address means "use whatever's configured in the
GPS control panel applet".

> So if NavIT can't find the bluetooth GPSr by itself I'm out of luck?
> (From what I've read, Navit can only access gpsd, not bluetooth or any
> other direct GPSr connection.) Someone has got NavIT running on an
> N800, but details are not available.

I'm sure there's a solution, but I'm not experienced enough to know what
it is.  This:

  Note that gpsd is only running when there is an application that
  wishes to get position data from GPS device. The libgpsmgr makes sure
  that even if there is multiple programs running that need location
  information, only one instance of gpsd is running.

        -- http://maemo.org/community/wiki/howtousegpsframeworkinos2007/

suggests to me that you should add a couple of libgpsmgr calls to NavIT
and then try to connect to gpsd, retrying a few times to give it a
chance to start up, as documented in
http://maemo.org/api_refs/4.0/gpsmgr/group__gpsmgr__api.html#g515fa304360969ba8d59e4e59a0eabf9

Or maybe using http://maemo.org/api_refs/4.0/gpsbt/ would be simpler, at
least the example given ("gpsbt_start(NULL, 0, 0, 0, &ctx);") in
http://maemo.org/api_refs/4.0/gpsbt/group__gpsbt__api.html#gdb860fb35f52c4beaf672d76adfc8c85
is clearer and doesn't require you to hardcode details such as GPS
device names but instead uses the configuration from the Control Panel.

Marius Gedminas
-- 
HOST SYSTEM RESPONDING, PROBABLY UP...

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