Hacks for the Nuvi 350

Not so far

That too remains a complete mystery!

http://www.gpspassion.com/forumsen/topic.asp?TOPIC_ID=88861

I agree, it'd be great to add custom software, customize the layout of the screens, etc., but I don't really expect it to happen. If GPS service was not free, I'm SURE someone would find a way to hack it until they found a way to get it for free. However, since it's already free, the 'hackers' probably have bigger things on their minds.

We can still keep our fingers crossed though..

We know it's an ARM processor. Look at the shutdown diagnostics and you see a CPSR register which is defined in the ARM architecture.

If you are familiar with computer architecture take a look at pg 8 ARM7 register set at http://tinyurl.com/2sjw4t

As far as the OS I have examined the binary in a hex editor and it's ARM assembler. There is no indication what OS is used. I suspect Vxworks or home grown closed os based on the licenses in the system about. No GPL or BSD license so probably not a Unix derivative. Note: the FreeType Project, JPEG and the Expat XML parser licenses.

Most embedded OSes are stripped to the bare minimum, so it may not be easy to determine the OS components.

The diagnostics screen showing the OS stacks really does not indicate an OS , but you can see the memory foot print of the functions of the OS.

Note: I have worked on various embedded OSes on various computer architectures (Intel, PPC, ARM, MIPS).

Could be palm OS? I knew that they made Aviation GPS software for the Palm OS and it is a lightweight fit for the function.

The Garmin iQue used Palm OS 5.2. I am pretty sure the nuvi os is not Palm OS based unless Access has stripped down version of Palm OS. I have not used an OS from Access since they bought PalmOS so I am not familiar with their recent offerings.

Ok, So I dont know exactly what to do with this information, so use it at your own risk.

I JUST DISCOVERED THE NUVI TEST MODE!

From your navigate screen, Touch the miles per hour in the lower left hand corner of the screen.

Touch the Speedometer on the top of the screen and hold your finger there for 5 seconds.

VIOLA! Theres more to my nuvi than I thought.

Anyone have any idea what the FM MODE is all about?
And why is there messages talking about XM Radio Compatibility?

Be careful...

Touch Overall Avg and hold Max Speed to see the stuff inside from available mem size to how much is in use. (just in case don't hit reset)

Another test mode (or something) can be accessed by holding your finger down on the Current Time in the upper right hand corner of the screen...

It enters a test mode that has a couple of nice video tests.

Now what do we do with this information... Does anyone understand it?

Some of it? It is just diagnostics pages for Garmin engineering and manufacturing. Manufacturing uses it to make sure your Garmin is not dead-on-arrival.

The batter test page is very useful! The number of cycles (Chrg Cycles) will tell you when your battery will die. Around 300-500 discharges/charge cycles until your battery will be worthless.The Bat Chrg stats are very useful for anyone making a homemade charger from parts.

The Audio Test page has a great tone generator you can use to tune a piano or guitar.

Data Card Test Page would be great to use if you suspect your data card is corrupting data.

Also we can extract some information on the design. It's an ARM based custom processor and a few other tidbits like the USB_ID which your Nuvi uses on USB bus to identify itself to your PC. I'd have to go through all the data....

you get it by holding your finger in the left upper corner as you are looking at the unit during power up. Also I noticed holding the power button down displays some boot message too, not sure what that's about.