Hacking the

Firmware

One guaranteed way to personalize your GPS is to update and modify the firmware that controls the actual running of the device. In this chapter, we’ll be looking at how you can modify your GPS at a

fundamental level.

Firmware

Firmware is the software that controls how hardware works and responds to inputs. It’s called firmware instead of software because users generally aren’t supposed to play around with it. But you’re not just any old user, are you?

Almost all electronic hardware contains some form of firmware. A television remote control contains firmware that controls what signals are sent via IR depending on what button is pressed. A cell phone contains a lot of firmware controlling cell access, phone books, security, and much, much more.

A GPS contains a lot of firmware controlling many of the key functions of the device (as shown in Figure 6-1):

Reception of satellite data

Decoding of positional information

Processing of data

Conversion of data into different formats

Interpretation and display of information

External communication with devices

Storing and managing route/waypoint data

chapter

in this chapter

˛What is firmware?

˛Steps for safe firmware updating

˛How to update firmware

˛Hacking the firmware

126 Part II — Software Hacks

Reception of data

Managing data

Decoding

Data display

Data conversion

Interpreting data	External
	communication

Data processing

FIGURE 6-1: The basic functions of a GPS receiver

As you can see, being able to influence the firmware means you have influence on the actual workings of the GPS receiver itself. Not only can you make alterations to the text that is displayed on the screen of the GPS, you can also hide features that get in the way (such as startup screens). You can also add your contact details to the GPS in such a way that would discourage theft of your unit and encourage its return to you if it were found.

But you have to be careful . . .

Updating Warnings

You must be careful when making any changes or modifications to the firmware of your GPS because there is a risk that things can go wrong and render the GPS inoperable. Problems are rare, however, and you can take steps to reduce, if not eliminate, firmware update problems:

1.Make sure your GPS contains a new set of batteries. Batteries suddenly dying midfirmware updating could cause big problems. Add fresh or recently recharged batteries, fire up the GPS, and confirm that the power levels are high. Figure 6-2 shows a healthy battery level in the lower-left corner of the screen on a Garmin eTrex.

2.Because you will be using a PC to do the update, it is better if the PC is connected to a UPS (uninterruptible power supply) battery backup, because the PC shutting off midupdate can be just as bad as the GPS battery dying. If you are using a laptop, power it from the mains supply or make sure the battery is fully charged.

Chapter 6 — Hacking the Firmware 127

FIGURE 6-2: Healthy battery level on a Garmin eTrex

3.Shut down any running applications, including screen savers that will appear if the system is left unattended.

4.Make sure the cable connection is sound. If you have a screw-in com port connector, attach it securely.

5.Don’t use the PC during the update — just in case it crashes and hangs the firmware update. Step away from the keyboard!

6.Finally, don’t jolt or shake the GPS while the firmware update is being piped to the device, as this can cause the connection to drop or the device to cut out.

Before making any changes to the firmware, I strongly recommend that you visit the website of your GPS’s manufacturer and download the latest firmware update and keep it handy.

Here are the websites of some of the most popular manufacturers:

www.garmin.com

www.magellangps.com

www.delorme.com

www.lowrance.com

www.laipac.com

www.haicom.com.tw

www.navman.com

www.miogps.com

www.emtac.com.tw

www.trimble.com

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If things do go wrong, there is a good chance you will be able to reload the firmware and get the GPS receiver unit back up and running.

Messing with the firmware of a GPS receiver is likely to invalidate the warranty, so take great care and weigh the benefits against the potential drawbacks. Everything described in this book has been tested by many people, but there is always a chance that things can go wrong.

Updating the Firmware

Updating the firmware on a GPS unit is a relatively easy process that takes only a few minutes. It varies slightly from unit to unit and maker to maker but usually the process is as follows:

1.Download the latest version of the firmware. A download package is shown in Figure 6-3. Make sure that the firmware that you download is the right firmware for the unit you are updating. Downloading and loading the wrong firmware onto a GPS unit is guaranteed to cause problems.

FIGURE 6-3: A firmware download package

2.Downloads are usually available in a zipped, or compressed, file. Uncompress the file and extract the contents. The file for an update to a Garmin unit is shown in Figure 6-4.

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

4.Run the main executable file that you extracted. This will begin the firmware updating process, as shown in Figure 6-5.

5.The firmware updating application will keep you posted as to the progress of the update.

6.After the update is complete, disconnect the GPS from the cable and switch it on — the system should fire up with the new firmware installed.