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.
context = gps.start()
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.
The code below shows how to connect with a GPS device, get data and close this connection:
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()
Download source code here.
- This page was last modified on 22 June 2010, at 11:51.
- This page has been accessed 2,792 times.