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-   -   Subaru Radio Digital Control Data Decoded (http://legacygt.com/forums/showthread.php?t=175168)

jazzymt 11-28-2011 09:07 PM

Subaru Radio Digital Control Data Decoded
 
Ok - first off - don't get your hopes up. I'm not sure how much farther I will take this, but after years of on & off working on this - being shelved multiple times due to busy life/jobs, etc. Check this out:

Using a logic analyzer I decoded the data protocol for the CD changer & radio (this was a royal pain). Then I programmed a microprocessor to read & display the data.

https://lh5.googleusercontent.com/-N...-54-47_833.jpg

Yay - it works!


ssbtech 11-28-2011 11:15 PM

Cool! Now for the climate control interface :p

jazzymt 12-01-2011 01:02 PM

I'm not sure if no one understand the significance of this or if just nobody cares anymore.

For those interested - the reason this is significant is because this can be used to both capture commands (like track fwd/rwd, etc.) and send phony info to the radio (like track time, number, etc.). In short - it can be used to fool the radio - negating the need for a silent CD - and it can be used to control an external device.

My plan right now is to continue development using a bluetooth chip so that you can stream music to your stereo with no external wires or soldering. Any device capable of sending audio via A2DP would be compatible. It also wouldn't be very difficult to add a provision for a mic and provide hands-free bluetooth calling capability through the stereo.

Chameleon 12-05-2011 11:45 PM

Nice job Jazzy glad you finally got the "break through" you have been working for. This will make life a lot easier when u accomplish creating the A2DP interface.

SVXdc 12-06-2011 02:03 AM

Great work!

That also means one could build a fairly basic device that only fools the HU enough so you can use the CD changer port as an aux input. Interfacing to/from an iPod would just be icing.

I wonder how many other Subaru HU models use that same protocol.

jazzymt 12-06-2011 07:50 AM

Quote:

Originally Posted by SVXdc (Post 3657660)
Great work!

That also means one could build a fairly basic device that only fools the HU enough so you can use the CD changer port as an aux input. Interfacing to/from an iPod would just be icing.

I wonder how many other Subaru HU models use that same protocol.

Fooling the headunit so you don't need a silent CD should not be very difficult at this point. I'm still debugging all possible messages (there is one when loading a CD that still interrupts comms that I'm working out) but I'm nearly there. Once it's purring like a kitten, I'll try it out on some Legacy radios I have. I assume they're very similar if not identical - but the MP3 version could be interesting since it has to read a lot more info (and text).

A2DP should be fairly straight forward at this point too. I've found a couple combinations of microprocessor/radios that have what I need. It's not the cheapest route to go, but it's the only sensible way for a do-it-yourself project.

Interfacing with an iPod is not going to be possible anymore though. A few years ago Apple locked down their products with authentication chips so that you can not develop an accessory for them without paying the Apple tax. If you're an iPod owner - you may recall the sudden need to buy all new adapters & higher prices for all Apple accessories. I wouldn't mind paying that per-item royalty really, but developing a MFI (made for ipod) accessory also has an entry fee of about $20-50k due to the required 3rd party testing prior to Apple's blessing. That ain't gunna happen.

I *could* buy a more expensive bluetooth module that has MFi approval so that you could stream music from your iPhone/iPod (bluetooth is also locked down with authentication), but I'll likely just continue with the 3rd party cable I'm using now for Apple users.

Malt Beverage 12-06-2011 03:48 PM

Even though I ditched the factory radio last year, I find this very interesting. Lazy subscribe :D.

technicalgarage 12-06-2011 03:52 PM

subscribed. love threads like this

jazzymt 12-08-2011 09:40 PM

Update 2
 
I think I have it running pretty good now. I changed some things up to handle the corrupted packet created when loading a new cd. Showing several radio functions including loading a CD, track up/dn, changer cd's loaded, etc.

Maybe this weekend some time I will grab a Legacy radio and see if I'm on the same page there or if I have to start over.

Also hoping my bluetooth chip shows up tomorrow and I can get started on that part (A2DP) once the Legacy radio's are in working order. UPS is starting to piss me off though - delayed delivery 2 days in a row now.

Until then..

jazzymt 12-10-2011 11:32 AM

Well the overwhelming lack of interest isn't exactly encouraging. Thanks for the couple that have posted. If anyone else is even remotely interested - please say something so I know you're there.

Until then - I guess I'll just keep going since I'm actually making progress. Here's a radio you might all recognize a little better. As I suspected - the CD changer module is identical and the communication protocol is too - without any changes I'm reading the Legacy GT CD changer with no problems.

Next I'll take a look at an MP3 changer & try to figure out A) How does it communicate title text, etc. B) Is that protocol also universal and can I display text on a non-MP3 radio?


Code 12-10-2011 11:49 AM

Subscribed

shoop 12-11-2011 04:07 AM

Quote:

Originally Posted by Code (Post 3663756)
Subscribed


balrock01 12-11-2011 08:49 AM

All I can say is WOW! I would love to connect my Android via BT and play through the car. Better than any FM modulator I am guessing. Subscribed

lilbrudder 12-11-2011 09:32 AM

Bt with my Droid would be great

Lucid 12-11-2011 10:21 AM

Subscribed


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