Chapter 2 — Building GPS Data Cables and Power Cords

37

The easiest way to solder these is to heat up the wire from the cable, coat that in solder, and then put the coated wire against the appropriate pin. Using the soldering iron, heat up the appropriate pin in the cradle and when the solder melts, take the soldering iron away to fix it. This minimizes the risk of short circuits and splashing solder on something important.

8.Make a hole in the cradle exterior for the wire to come out of. Once you have done that, reassemble the cradle and then confirm that you can access your GPS from the iPAQ via the cradle.

Testing the Connection

The easiest way to test the connection is to use simple software, and software doesn’t come much simpler than WinFast Navigator. This application is available free for download (the best, most reliable source for this can be found at www.pocketgpsworld.com/modules.php?name= Downloads&d_op=getit&lid=15) and can be installed and up and running on a Pocket PC device in minutes. Once installed, you should find Navigator showing on your Start menu.

Set your GPS to the NMEA data transfer protocol (more than 95 percent of units support this standard, and although it is old and a bit slow compared to the more modern SiRF, it is still likely to remain popular for a long time to come). Now connect the GPS to the cable connected to the cradle and seat the iPAQ in the cradle. Tap View and then Diagnostics. This will present you with another screen devoid of data, as shown in Figure 2-28. This is the diagnostics screen, and it’s best to be sitting on this when you try to connect.

You can find more information on these protocols in Chapter 9.

FIGURE 2-28: WinFast Navigator

If you don’t see any data appear onscreen when connected, there is a problem somewhere — usually the wrong settings have been input. Connecting to the GPS unit can involve quite a lot of trial and error until you find the correct settings.

38 Part I — Hardware Hacks

Now tap Tools followed by Settings and you will see the window shown in Figure 2-29.

FIGURE 2-29: The settings window

This shows you the protocols available (e.g., NMEA and SiRF), the serial port on which you will connect, and the baud rate to use.

I recommend that you always try out NMEA first, so make sure this is selected. When it comes to baud rate (the rate at which communication should occur, measured in bits per second), generally NMEA prefers to use 4800, so make sure it’s set to that.

For the Port setting, you know that you are connecting to a GPS receiver that plugs into the bottom of the sync port, and most of the time this is regarded as Serial1 COM1, so you can set it to this.

Tap the OK button. You should be taken back to the Development window in WinFast Navigator, where you should see a screen like the one shown in Figure 2-30.

FIGURE 2-30: Development window in WinFast