Real-time GPS to GMap

A quick mash-up to display GPS position data from a bluetooth GPS device in real-time on a Google map inside a web browser.

Built using a signed processing applet to read NMEA GPS-data from a RoyalTek RBT 2210 via the bluetooth RFCOMM profile (using the bluecove implementation of javax.bluetooth), parse it and send it to a Google map using the Google Maps API, JSObject and JavaScript.

 

This should be working with other NMEA GPS devices, too. Possibly StupidNMEAParser.parseNMEAString(String s) has to be changed.

 

 

Code snippets

Connecting using the RFCOMM profile:

 

void connect() {
  try {
    StreamConnection con = (StreamConnection)Connector.open(RBTUrl);
    is = con.openInputStream();
  } catch (IOException ioe) {
    ioe.printStackTrace();
  }
}

Read data:

void read() {
  if (is==null) return;
  try {
    char inchar;
    if (is.available()<=0) {
      return;
    }
    while (is.available()>0) {
      inchar = (char)is.read();
      inb.append(inchar);
      if (inchar=='n') {
        parser.parseNMEAString(inb+"");
        inb = new StringBuffer();
      }
    }
  } catch (IOException ioe) {
    ioe.printStackTrace();
  }
}

Parse data:

void parseNMEAString(String s) {
    if (s.indexOf("$GPGGA")==0) {
      try {
        String[] matches = s.split(",");
        String time = matches[1];
        float lat = Float.parseFloat(matches[2]);
        lat /= 100.0;
        lat = floor(lat) + (lat%1)/60.0*100.0;
        if (matches[3].equals("S")) lat = -lat;
        float lng = Float.parseFloat(matches[4]);
        lng /= 100.0;
        lng = floor(lng) + (lng%1)/60.0*100.0;
        if (matches[4].equals("W")) lng = -lng;

        gotPosition(new LatLngTime(lat, lng, time));
      } catch (Exception e) {
        e.printStackTrace();
      }
    }
  }
}

Accessing JavaSript:

JSObject window = JSObject.getWindow(this);
...
window.eval("addMarker("+pos.getLat()+","+pos.getLng()+")");

Source Codes

› nmea2gmap.zip (100 KB)

› applet.zip (272 KB)