[maemo-users] accessing N900 internal gps for console apps

From: Jason maemo at lakedaemon.net
Date: Thu Dec 24 04:57:55 EET 2009
Jason wrote:
> Craig Woodward wrote:
>>> ---- Jason <maemo at lakedaemon.net> wrote:
>>> ============= Aldon Hynes wrote:
>>>> For a good starting point, I would recommend 
>>>> http://wiki.maemo.org/PyMaemo/Using_Location_API
>>> Okay, that's a good start.  I found the raw C api here [1].  Does
>>> this generate a tcp listener socket on 2947?  It doesn't look like
>>> it.  :-( I'm shooting for a gpsd equivalent so existing gpsd aware
>>> apps don't need to be modified.
>>> [1] - 
>>> http://maemo.org/api_refs/5.0/beta/liblocation/LocationGPSDControl.html
>> A better idea may be to write a mini-gpsd specifically for the N900
>> that translates between the location API and the port.  This would
>> allow the best of both worlds, since we save power when not used and
>> apps talking gpsd can run without major changes.
> I saw that app (minigpsd [2]) in one of the maemo repos, but apt-get
> install failed with unmet dependencies.  As it was in -testing I figured
> it was a work-in-progress and looked to other things...
> The unmet dependencies were:
> #### begin #############
> The following packages have unmet dependencies:
>   minigpsd: Depends: bluez-utils-test but it is not installable
>             Depends: python2.5-gnome but it is not installable
> E: Broken packages
> #### end ###############
> As for a proposed project, it may be easiest to gin up a patch against
> gpsd, adding support for liblocation.  I'd be curious which NMEA
> sentences liblocation spits out.  If it just passes along what it
> receives, that would be great.
> [2] - http://maemo.org/packages/view/minigpsd/

Grrrr.  I took a closer look at the Python API, since it spells out what
is returned...  I could do GLL, maybe RMC, but I'm not sure I can create
a proper GSV from it.  :-(

It would probably be better to write a small daemon that accesses
liblocation and emulates a dumb serial gps, writing raw NMEA sentences
to the psuedo serial port device.  gpsd could then listen on that.
Since 'sb2 apt-get source liblocation' failed, I presume liblocation
isn't open source.  What a pity.

I'll take a closer look tomorrow.



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