What we need now is a way to extract each individual sentence out of the stream to be passed for parsing to the NMEA object. For that I wrote the wf_get_token function. This will extract a string based upon a delimiter. For the NMEA stream, that is the newline character.

Finally, we will need a way to convert the latitude and longitude returned by the receiver to decimal degrees. This is necessary for the MapPoint method GetLocation. The formula for doing so is:

There are some other conversions necessary for GetLocation as well. They are as follows:

We can determine the sign based upon the direction returned by the NMEA sentence. Finally, we can map our current position by using the following MapPoint code.

loo_Location = ioo_Map.GetLocation(ldb_Lat, ldb_Long, ldb_Alt)
loo_PinCurrentFix=ioo_Map.AddPushpin(loo_Location,"You are here!")
loo_Location.GoTo()
loo_PinCurrentFix.Select()

There are many other operations you can perform in MapPoint, for example, directions from point A to point B. A good resource is an article written in PBDJ (Vol. 11, issue 10) entitled "Using MS MapPoint in PowerBuilder" by Arthur Hefti. The source for that article can be found here: http://gemsres.com/story/jul05/107019/source.html.

Step 5: Put it all together. Add the following code to the clicked button of your "Get GPS Data" button.

ib_Connected = wf_detect_bt()
If ib_Connected Then
      wf_write_gps()
      sleep(3)
      wf_read_gps()
End If

Step 6: Cleanup

ole_MapControl.Object.CloseMap()
wf_close_bt()

That's it.

One final note, if you plan on connecting to a Bluetooth serial port greater than COM9, you will need to use this syntax "\\.\COMxx" as the port name. Just substitute the port number you wish to use for xx. The cause of the problem is that CreateFile accepts strings "COM1" - "COM9" as names of devices but rejects doing so for two or more digit numbers.

If you are interested in learning more, check out the following references. In addition, you can find the complete source code for this project on CodeExchange in the PowerBuilder special hardware section.

Resources

• How GPS Receivers Work: http://electronics.howstuffworks.com/gps.htm
• A General Overview of the NMEA Protocol: www.gpsinformation.org/dale/nmea.htm
• Powerbuilder MapPoint Code Examples: http://gemsres.com/story/jul05/107019/source.html