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GPS timeout in python

Hello!

I've followed the guide on http://wiki.maemo.org/PyMaemo/Using_Location_API. The purpose is to every 3rd hour connect with the GPS, fetch 10 coordinates and send them to my server. If I lose my phone I can always go to my server and find the coordinates of the phone. The script works fine, but the problem occurs when I enter a closed building without GPS-reception, then my phone tries forever until it finds GPS-reception which ofcourse drains the battery. So I'd like to implement a function that cancels the update if the script takes longer than 5 minutes. How can this be made?

Thanks!

Code:

import location

import gobject





x=0

 

def on_error(control, error, data):

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

    data.quit()

 

def on_changed(device, data):

    global x



    if not device:

        return

    if device.fix:

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

            #http://maps.google.com/maps?q=62.62991%2C17.040443

            print "http://maps.google.com/maps?q=%f,%f" % device.fix[4:6]

            if x>8:

                #commented out to allow continuous loop for a reliable fix - press ctrl c to break the loop, or program your own way of exiting)

                    data.stop() 

            else:

                x=x+1

                

 

def on_stop(control, data):

    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_5S)

 

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()

Re: GPS timeout in python

Just a rough explanation.

When you start the GPS register the time

Code:

global StartTime

StartTime = time.time()

Then in the function you listen for the GPS changes add a check

Code:

PastTime = time.time() - StartTime

if PastTime >= GPSTIMEOUT:

   data.stop()

ofcourse you need to import time.

I think this is all you need to make it work, this is also how the smscon_daemon does it.

Re: GPS timeout in python

Yes, I've tried similar like that. But the problem is that when the GPS doesn't find any coordinates (i.e. doesnt have any reception) it doesn't change and therefore that function doesn't update. So I need to put it somewhere else

Re: GPS timeout in python

a suggestion...
invoke a shell script that checks for the GPS update and run the shell script in background mode using & before calling this script put a counter (timer) and if it exceeds limit (say 5 mins) , kill the shell script using PID from ps -ef <shell script name> and the kill -9 command.

Re: GPS timeout in python

You know, you could use Google Latitude and ZapLoc to do this...

But anyway, in ZapLoc, I have two timers.

One timer in the main loop, which is the polling interval. Then, when that timeout calls its function, that function setts up a second timeout, which turns the GPS back off.

Note that timeouts using the gobject.timeout_add() function, if the function you call return True, it will loop and repeat your timeout, if it returns False, it will only happen once.

So roughtly, I have something like this:

Code:

def turn_off_gps(control):

     control.stop()

     return False



def start_gps(control):

    control.start()

    gobject.timeout_add(30000, turn_off_gps, control)

    return True



def init ():

   control =  ...

   gobject.timeout_add(120000, start_gps, control)

Roughly, this will start the GPS every two minutes, and keep it running for 30 seconds.

/Z