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FIGURE 6-4: Files contained in the update

FIGURE 6-5: Beginning the firmware update process

That’s all there is to it! I suggest you read any material that accompanies the update (especially any README files contained in the download package) to familiarize yourself with any new features of the firmware and to get any late-breaking information. Many vendors add new features to their GPS units well after release through firmware updates. Be careful about installing updates that have only just been released. Generally, I wait a week or two before updating so that if any bugs are found in the firmware update, they can be fixed before I install it.

Of course, uploading new firmware to a GPS is not hacking the firmware at all, so let’s move on to actual firmware hacking!

Hacking GPS Firmware

The following sections describe how you can hack and tweak the firmware on a GPS unit. In this section, you will learn how you can bypass the startup screen on three different GPS receivers.

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You won’t be able to get any support from the manufacturer for altering or modifying the firmware. In fact, having modified firmware on the device may well invalidate your warranty.

Bypassing the Garmin eTrex Vista Startup Screen

One annoying feature of the eTrex range is that when the unit starts up, it takes you to a startup screen. This means you have to press buttons or wait for the satellite screen, which I find really annoying. There is a way around this, but only using an older firmware version (2.28 as opposed to the latest 3.60). However, using older firmware does mean that you lose

any new features introduced (such as the JumpMaster feature — however, this particular feature is only relevant to experienced parachutists).

Here’s how to bypass the startup screen:

1.Download a copy of the latest firmware from the Garmin website (www.garmin.com). Keep this just in case of problems.

2.Download a copy of the 2.28 version firmware for the Garmin eTrex Vista from www. gpsinformation.org/perry/vista/Vista_2_28.exe (read the agreement at www.gpsinformation.org/perry/agree.html first).

3.The download comes in a compressed file. Uncompress the file and extract the contents.

4.Find the file called 016901000228.RGN, as shown in Figure 6-6.

FIGURE 6-6: The main file that contains the firmware information

5.You now need a program called a hex editor. I’m using one called UltraEdit, available from www.ultraedit.com (shown in Figure 6-7), but many are available on the Internet so fire up your browser and do a search for “hex editor.” You need to open 016901000228.RGN and make a few small edits to it.

6.Go to the address 00024024 (there is a go to function in most good hex editors) and change F5 to 6D, as shown in Figure 6-8.

7.Go to the address 00024025 and change 24 to BA, as shown in Figure 6-9.

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FIGURE 6-7: UltraEdit in action

FIGURE 6-8: Make a change to the firmware.

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FIGURE 6-9: Make another change.

8. Go to the address 00024026 and change 03 to 04, as shown in Figure 6-10.

FIGURE 6-10: The final change!