Firmware Disassembly

Ido Bar-Tana ido.bartana@gmail.com
 

1.  Introduction

This page is a live document of my effort to disassemble and understand the Garmin Etrex firmware. If you're interested in this effort and especially if you're willing to participate in it, please contact me. There is a CDROM loaded with ARM tools I can send you if you are able and willing to participate.

The Garmin etrex is built around the StrongARM processor. The firmware is downloadable and includes both the data and the graphics used in the various screens.

2. What I've got so far

Not much actually, but here goes.

• Links to current and past firmwares. This may be useful for compares and understanding (for example, the additional 'advanced skyview' screen, added to version 2.10).

• I have mapped the graphics images for version 2.10, that latest firmware. The table at the end of the page shows this mapping. You can also download an Excel version of this table.
• I have an evaluation version of the ARM developer suite. It includes the ARM C,C++ compiler, IDE (codeworrior), Extended Debugger, Instruction Set Simulator and tons of documentation. It is freely available from ARM. Using the Extended Debugger, I can easily disassemble the firmware. Understanding what I'm seeing is, well, a different story.

3. Worthy goals

• Create a 'summit' firmware version, that'll display an altitude profile of the trackback log. Now if the source code was available, this would have been pretty much a copy-paste operation.
• Let me know your wishlist (but please don't hold your breath)