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.
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.
Example
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.