maemo.org - Talk - new python GPS wrapper (liblocation.py)

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Re: new python GPS wrapper (liblocation.py)

Pity that liblocation API must have changed. I went with that since it seemed to be the most "officially documented" way of accessing the GPS in maemo and therefore the least likely to change.

I not going to attempt to migrate the code because I don't have an n900 device to test with. If someone else would like to try it, it should involve making the python ctypes structures and function calls line up with whatever is now changed in the C API. This would involve chasing through the new liblocation docs and header files. The python wrapper is very thin so there's not a whole lot that can be going wrong, unless the new API is radically different.

Re: new python GPS wrapper (liblocation.py)

Quote:

Originally Posted by yerga (Post 403610)

The GPS module is being worked by the Pymaemo guys. They have something in the SVN and they will be pushing a package to the repository soon enough.

http://wiki.maemo.org/PyMaemo/Using_Location_API
https://bugs.maemo.org/show_bug.cgi?id=5748#c2

I finally had a chance to look at this, and it seems there are some problems:

using the example code:

Code:

import location

import gobject



def on_error(control, error, data):

    print "location error: %d... quitting" % error

    data.quit()



def on_changed(device, data):

    if not device:

        return

    if device.fix:

        if device.fix[1] & location.GPS_DEVICE_LATLONG_SET:

            print "lat = %f, long = %f" % device.fix[4:6]

            data.stop()



def on_stop(control, data):

    print "quitting"

    data.quit()



def start_location(data):

    data.start()

    return False



loop = gobject.MainLoop()

control = location.GPSDControl.get_default()

device = location.GPSDevice()

control.set_properties(preferred_method=location.METHOD_USER_SELECTED,

                       preferred_interval=location.INTERVAL_DEFAULT)



control.connect("error-verbose", on_error, loop)

device.connect("changed", on_changed, control)

control.connect("gpsd-stopped", on_stop, loop)



gobject.idle_add(start_location, control)



loop.run()

it runs, however, the result returns immediately with:

Code:

Nokia-N900-42-11:~# python test-location.py

lat = 39.400000, long = 0.000000

quitting

No matter what I change the preferred_method= to it always returns instantaneously - even if I reboot the phone to force a cold-start.

Lat is 1.4 degrees south of my current position, and Long is zero which isn't right either....

Re: new python GPS wrapper (liblocation.py)

Follow up to this (I got it working)

I posted my question to the pymaemo developer list and one of the developers, David, pointed out the problem with the code exiting the first time on_changed() gets called when it hasn't fulling acquired a fix. Commenting out the data.stop() line allows a 2nd call to acquire the full fix:

Code:

Nokia-N900-42-11:~# python test-location2.py

lat = 39.400000, long = 0.000000

lat = 40.796683, long = -73.922741

Also, I had updated my location server from supl.nokia.com to supl.google.com per this post: http://talk.maemo.org/showpost.php?p...3&postcount=14

Allowed me to get a quick network-based fix in the Ovi Maps app indoors. Before using the old server I could never get a fix.

Re: new python GPS wrapper (liblocation.py)

Hi
Do you have and example like this but using ctypes?
I need a faster refresh and this wrapper only allows 1 sec or higher

thanks

Re: new python GPS wrapper (liblocation.py)

Quote:

Originally Posted by dhcmega (Post 572296)

Hi
Do you have and example like this but using ctypes?
I need a faster refresh and this wrapper only allows 1 sec or higher
thanks

Have you tried playing with the python-location? See http://wiki.maemo.org/PyMaemo/Using_Location_API for an example .

Re: new python GPS wrapper (liblocation.py)

lizardo, that is the one i have used. but it only allows a max rate of 1 position refresh per second and i need a position refresh of at least 0.1 of second.
thanks