PyMaemo/Python-GPSbt

Introduction

Python-GPSbt is a binding, based on libgpsbt, that provides access to GPS data through osso-gpsd. It only depends on a Bluetooth GPS device already paired. How it works

Libgpsbt allows to connect with Bluetooth GPS devices and uses osso-gpsd daemon to provide a socket where you can send/receive information.

After a gps.start() its possible to send commands (trhough query) and receive data from GPS. Almost all information acquired from socket is stored inside a structure called 'fix'. To fill it just call the get_fix(). It does a query to get all necessary information from GPS device.

To finish the Bluetooth connection just call the gps.stop() method, providing the context (returned by gps.start()). API

• gpsbt.start - establishes a new GPS connection and returns a context. This one is is used to inform stop method what connection to be ended.

<source lang="python"> context = gps.start() </source>

• gpsbt.stop - ends an active connection, passed through the context. gps.stop(context)
• gpsbt.gps() - the class that gets information from GPS. Through it its possible to query, get_fix, get_position, etc.
• gpsbt.gps.get_fix() - fills in the 'fix' structure with GPS data. The fields are: mode, time, ept, latitude, longitude, eph, altitude (meters), epv, track (degrees from true north), speed (knots), climb (meters per second), epd, eps and epc.
• gpsbt.gps.get_position() - its a shortcut to return (latitude, longitude) info.
• gpsbt.gps.query() - allows user to send one letter commands to the GPS device. Its possible to group a sequence of commands to send, e.g.:
  • gpsbt.gps.query('a') fills in the altitude field of 'fix' structure
  • gpsbt.gps.query('as') fills in the altitude and speed fields
• gpsbt.gps.satellites - contains a list of detected satellites, including information about usage and quality.

Example

The code below shows how to connect with a GPS device, get data and close this connection: <source lang="python"> import gpsbt import time

def main():

   context = gpsbt.start()

   if context == None:
       print 'Problem while connecting!'
       return

   # ensure that GPS device is ready to connect and to receive commands
   time.sleep(2)
   gpsdevice = gpsbt.gps()

   # read 3 times and show information
   for a in range(4):
       gpsdevice.get_fix()
       time.sleep(2)

       # print information stored under 'fix' variable
       print 'Altitude: %.3f'%gpsdevice.fix.altitude
       # dump all information available
       print gpsdevice

   # ends Bluetooth connection
   gpsbt.stop(context)

main() </source>

Download source code here.