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Chapter 6 — Hacking the Firmware 133

9.Connect the GPS unit to the PC using the appropriate cable and switch the GPS receiver on.

10.Run the main executable file that you extracted. This will begin the firmware update process.

11.The firmware updating application will keep you posted as to the progress of the update. The process will complete reasonably quickly and the GPS will be ready for use.

Bypassing the Garmin eTrex Legend Startup Screen

The Garmin eTrex Legend suffers from the same problem as the Vista in that is has a startup screen that you must wait to get past. There is a way around this, but only using an older firmware version (2.41 as opposed to the latest 3.60).

This example uses UltraEdit as the hex editor.

Here’s what you do:

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 2.41 version firmware for the Garmin eTrex Vista from www. gpsinformation.org/perry/legend/Legend_2_41.exe (read the agreement at www.gpsinformation.org/perry/agree.html first).

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

4.Find the file called 017901000241.RGN.

5.Open 017901000241.RGN in a hex editor and make the following changes to it.

6.Go to the address 000229DC (there is a go to function in most good hex editors) and change 91 to 49.

7.Go to the address 000229DD and change DE to 39.

8.Go to the address 0011CB07 and change 91 to 7E.

9.Connect the GPS unit to the PC using the appropriate cable and switch the GPS receiver on.

10.Run the main executable file that you extracted. This will begin the firmware update process.

11.The firmware updating application will keep you posted as to the progress of the update. The process will complete reasonably quickly and the GPS will be ready for use.

Bypassing the Garmin eTrex Venture Startup Screen

Just like the Garmin eTrex Vista and Legend, the Venture also suffers from the same problem as the Vista in that is has a startup screen that you have to get past.

134 Part II — Software Hacks

Like the other models, the way around this uses an older firmware version (2.34 as opposed to the latest 3.70).

Here’s what you do:

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

2.Download a copy of the 2.34 version firmware for the Garmin eTrex Vista from www. gpsinformation.org/perry/venture/etrexventure_mariner_234.exe (read the agreement at www.gpsinformation.org/perry/agree.html first).

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

4.Find the file called 015401000234.RGN.

5.Open 015401000234.RGN in a hex editor to make the following changes.

6.Go to the address 0001F4DC (there is a go to function in most good hex editors) and change E1 for C9.

7.Go to the address 0001F4DC and change 99 to FE.

8.Go to the address 0001F4DE and change 02 to 01.

9.Go to the address 000D002F and change A7 to 5B.

10.Connect the GPS unit to the PC using the appropriate cable and switch the GPS receiver on.

11.Run the main executable file that you extracted. This will begin the firmware update process.

12.The firmware updating application will keep you posted as to the progress of the update. The process will complete reasonably quickly and the GPS will be ready for use.

MeMap Personalization

An interesting way to personalize the text that displays on your Garmin eMap and eTrex range GPS is to use a program called MeMap. The MeMap firmware editing package is available for download on the web from Ido Bar Tana’s site at www.geocities.com/etrexkb/ textpatch.zip. More information about the application can be found at www.geocities. com/etrexkb/textpatch.htm.

MeMap enables you to search for text strings within the firmware so that you can edit them with your own strings.

MeMap was written by Gilles Kohl (http://ourworld.compuserve.com/homepages/ gilles/memap/index.htm).

This product is free, so it won’t cost you anything if you want to experiment.

Chapter 6 — Hacking the Firmware 135

While this software does what it says it does, it can be a little quirky at times and your initial efforts may not work. If this is the case, revert to the original firmware and try again.

One possible quirk you might come across is that the preview screen displays the text upside down and left to right. This is because of the way that certain firmware versions store the text within their code. If you see this, don’t worry; things should work out for you fine anyway.

The Garmin eTrex range includes the following units:

Basic yellow

Camo

Legend

Venture

Summit

Vista

Before you start, you will need the following:

Garmin eTrex range GPS

A cable to connect the GPS to a PC

A PC running Microsoft Windows on which to run the software

The process involved is a simple one. Here’s what you need to do:

1.Download the software from www.geocities.com/etrexkb/textpatch.zip. The zipped file is shown in Figure 6-11.

FIGURE 6-11: The compressed application

2.Extract the contents of the file to a convenient folder on your PC. The contents of the file are shown in Figure 6-12.

136 Part II — Software Hacks

FIGURE 6-12: Contents of the MeMap download

3.Because the software works on a firmware file (files that have the extension .RGN), you should now download a copy of the appropriate firmware for your device from Garmin (www.garmin.com/support/download.jsp).

4.Extract the files from the firmware download into a convenient location.

5.Copy the .RGN file from the location in which you extracted the firmware and copy it to the location of the MeMap application.

6.Now run the MeMap application (memap.exe). After a few seconds, the application will start and you will be presented with the main screen, as shown in Figure 6-13.

FIGURE 6-13: MeMap main screen

7.You can now start searching for strings to replace. A good one to start with is “WARNING,” as shown in Figure 6-14.

FIGURE 6-14: Searching for the word “WARNING”

Chapter 6 — Hacking the Firmware 137

8.Click the button marked Search! This will take you to the first instance of the string found in the firmware. This is shown in Figure 6-15.

FIGURE 6-15: The first instance of the word “WARNING” in the firmware

9.You can now either choose to make edits to the text at the location of the word you searched for in the firmware or you can click the button marked Find Next to find the next instance of the string in the firmware. The string to be replaced is shown in the upper-left window, while the text to replace it with is in the lower-left. Figure 6-16 shows some edits I have made.

10.When you have finished making edits based on a particular keyword, click OK to take you back to the main screen.

FIGURE 6-16: Making edits to the firmware

138 Part II — Software Hacks

11.You can also search for your own strings using the box at the bottom of the main screen. In Figure 6-17, we are searching for the string “GPS”.

FIGURE 6-17: Searching for the term “GPS”

12.The longer the search string that you search for, the better. If you search for a small string, you will find many instances of them, whereas longer strings narrow the search better (see Figure 6-18).

FIGURE 6-18: Longer strings provide better results, as short search strings return a large number of results.

13.After you are done making changes, click OK to close the edit window.

14.Now click Exit to close the application, and then click Yes to save the changes (see Figure 6-19).

15.All that remains for you to do now is to take the firmware and load it onto your GPS and try it out. If everything has worked thus far, the firmware should work — if you have problems, reload the original firmware on the device and try again.