Linux/Ubuntu/GoogleEarthPlusRealTimeGPS: gegpsd.py

#!/usr/bin/python

# Copyright (C) 2007 by Jaroslaw Zachwieja <grok!warwick.ac.uk>
# Copyright (C) 2008 by TJ <linux!tjworld.net>
# Published under the terms of GNU General Public License v2 or later.
# License text available at http://www.gnu.org/licenses/licenses.html#GPL

import serial
import string
import sys
import getopt

def usage():
                print "Usage:"
                print " -p | --port <device>   e.g. /dev/ttyS0"
                print " -b | --baud <speed>    e.g. 4800"
                print " -f | --file <filename> e.g. /tmp/gps.kml"
                print " -h | --help     display options"

def main():
        # defaults
        serial_port = "/dev/ttyS0"
        serial_baud = 4800
        file = './realtime/Realtime GPS.kml'

        try:
                opts, args = getopt.getopt(sys.argv[1:], "p:b:f:h", ["port=", "baud=", "file=", "help"])
        except getopt.GetoptError:
                usage()
                sys.exit(1)
        else:
                for opt, arg in opts:
                        if opt in ("-p", "--port"):
                                serial_port = arg
                        elif opt in ("-b", "--baud"):
                                serial_baud = string.atof(arg)
                        elif opt in ("-f", "--file"):
                                file = arg
                        elif opt in ("-h", "--help"):
                                usage()
                                sys.exit(0)
                        else:
                                print "Unknown option"

        gps = serial.Serial(serial_port, serial_baud, timeout=1)

        print "Serving data from %s (%d baud) to %s" % (serial_port, serial_baud, file)

        latitude = 0
        longitude = 0
        speed = 0
        heading_in = 0
        altitude = 0
        range = 1000
        tilt = 30

        while 1:
                line = gps.readline()
                datablock = line.split(',') 

                if line[0:6] == '$GPRMC':
                        latitude_in = string.atof(datablock[3])
                        longitude_in = string.atof(datablock[5])
                        try:
                                altitude = string.atof(datablock[8])
                        except ValueError:
                                # use last good value
                                altitude = altitude
                        speed_in = string.atof(datablock[7])
                        try:
                                heading_in = string.atof(datablock[8])
                        except ValueError:
                                # use last good value
                                heading_in = heading_in
                        if datablock[4] == 'S':
                                latitude_in = -latitude_in
                        if datablock[6] == 'W':
                                longitude_in = -longitude_in

                        latitude_degrees = int(latitude_in/100)
                        latitude_minutes = latitude_in - latitude_degrees*100

                        longitude_degrees = int(longitude_in/100)
                        longitude_minutes = longitude_in - longitude_degrees*100

                        latitude = latitude_degrees + (latitude_minutes/60)
                        longitude = longitude_degrees + (longitude_minutes/60)

                        speed = int(speed_in * 1.852)
                        range = ( ( speed / 100  ) * 350 ) + 650
                        tilt = ( ( speed / 120 ) * 43 ) + 30
                        heading = heading_in

                        if speed < 10:
                                range = 200
                                tilt = 30
                                heading = 0

                        output = """<?xml version="1.0" encoding="UTF-8"?>
        <kml xmlns="http://earth.google.com/kml/2.0">
                <Placemark>
                        <name>%s km/h</name>
                        <description>^</description>
                        <LookAt>
                                <longitude>%s</longitude>
                                <latitude>%s</latitude>
                                <range>%s</range>
                                <tilt>%s</tilt>
                                <heading>%s</heading>
                        </LookAt>
                        <Point>
                                <coordinates>%s,%s,%s</coordinates>
                        </Point>
                </Placemark>
        </kml>""" % (speed,longitude,latitude,range,tilt,heading,longitude,latitude,altitude)

                        f=open(file, 'w')
                        f.write(output)
                        f.close()

        ser.close()

if __name__ == "__main__":
        main()