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Discussion Starter · #1 ·
FINALLY: CDC protocol on HU(-1205) has been reverse engineered!

8/8/2006: See pages 17+ for exciting news and examples.

FINALLY!

After months of hard work I've managed to reverse engineer the CDC protocol on my HU-1205 navigation radio! I'll post some pictures of the work and the prototype, if I found out how...


I will soon open a website with more info (and maybe orderinfo....
)

As to be expected, the protocol is completely emulated by a microcontroller, I used an Atmel AT90s2313. Since I own an iPOD, I also embedded some remote commands to control the iPOD. Currently play/pause, next/prev track and rew/ffwd search are supported. In other words, I can control the iPOD from my HU!

Pretty cool, eh?
 

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Discussion Starter · #4 · (Edited)
Re: FINALLY: CDC protocol on HU(-1205) has been reverse engineered! (mrg_Ed)

I got it! Here are the pics:

Work in progress:
here you see the first prototype working! On the right hand you see a bunch full of wires which connects the microcontroller to the HeadUnit. The headunit (HU) displays cd 09, track 99. In the microcontroller software I tried to display cd 99 but it only goes 'till 10 apparently. Further you see the iPOD connected to the HU (audio in) and playing music, which, of course, can be heard via the HU


Here are two pictures of the first official prototype which includes iPOD control via HU (play/pause when HU changes to CD-C /back to radio, when telephone mute is enabled, when radio is switched on / off; next/prev track; rew/ffwd )




The prototype simply plugs into the HU via an 8-pin DIN cable and provides a stereo aux input via 2 RCA plugs.
 

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Re: FINALLY: CDC protocol on HU(-1205) has been reverse engineered! (mrg_Ed)

That's really great news. Unfortunately, for HU-1205 is not available in the North American market. But I'm sure your adapter will work on other HU-xxx units since its also made by Melco.
Questions: I realize the HU-1205 is a radio with RTI but I wonder if your adapter will work with a wide screen DVD based RTI system. I ask because the USA*Spec CD Changer unit does not appear to work with radios with RTI. They admitted to a fault with the firmware.
Secondly, as far as you know, does the Melco HU-xxx radios have provision to show song titles on the HU display??
 

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Discussion Starter · #7 ·
Re: FINALLY: CDC protocol on HU(-1205) has been reverse engineered! (MrTippy)

Q: I have the 10 disc cd changer in my car. Do you think your adapter will work with it present?

A: I've reverse engineered the protocol based on this 10 CD-C (branded by Volvo, but originally build by Mitsubishi), which I bought especially for this project. so that should not be a problem...

Modified by mrg_Ed at 11:33 PM 1-13-2005
 

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Discussion Starter · #8 ·
Re: FINALLY: CDC protocol on HU(-1205) has been reverse engineered! (R-Car)

Q: I realize the HU-1205 is a radio with RTI but I wonder if your adapter will work with a wide screen DVD based RTI system. I ask because the USA*Spec CD Changer unit does not appear to work with radios with RTI. They admitted to a fault with the firmware.

A: I'm not sure, I've reverse engineered the so called melbus protocol that exists between HU and CDC. If other systems provide this as well (have the capability to connect the 10 CD-C from Volvo) it might possibly work.

Q: Secondly, as far as you know, does the Melco HU-xxx radios have provision to show song titles on the HU display??

A: There are no signs in the protocol data in order to display extra info like song titles playlists, etc. I've been looking for it, since the iPOD provides these features.
Theoretically, it might be supported by the protocol, but the CD-C doesn't reveal the data, so I don't know.

Modified by mrg_Ed at 11:29 PM 1-13-2005
 

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Re: FINALLY: CDC protocol on HU(-1205) has been reverse engineered! (mrg_Ed)

That's what I thought, it may be difficult, if not impossible, to display song titles, etc. with the current line of HUs as they stand now. Perhaps a HU firmware upgrade from Volvo would change that. So do you feel like reverse engineering the HU's firmware to add this capability??
Seeing that you are successful in simulating the CDC, does the code going from your adapter to the head unit have any pattern? What I mean is that by changing/rearranging the code pattern, would it be possible to open up another channel such as the DAB, MD, etc. If you are successful at that, then you can make a multi-input adapter. This would be well suited to many owners here as many want to connect their iPod, satellite radio, etc. and be able to select them from the HU. So for example, you can select CDC (CD CHGR) for those that have the Volvo CD Changer already installed, the DAB for those with satellite radio, MD for iPod.
Since the HU is capable of controlling and changing 10 discs, can you change the playlist on the iPod by turning the change disc knob and perhaps match the playlist with the disc number on the display? At least you can choose between 10 playlists on the iPod from the HU. Can you also change the iPod to shuffle play when you press the RND button?? I have so many ideas!!!
BTW, I think you have done something that the likes of Soundgate and Blitzsafe have failed to do. For that, I applaud your efforts!

Modified by R-Car at 2:15 AM 1-14-2005
 

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Discussion Starter · #10 ·
Re: FINALLY: CDC protocol on HU(-1205) has been reverse engineered! (R-Car)

Quote, originally posted by R-Car »
That's what I thought, it may be difficult, if not impossible, to display song titles, etc. with the current line of HUs as they stand now. Perhaps a HU firmware upgrade from Volvo would change that. So do you feel like reverse engineering the HU's firmware to add this capability??
Seeing that you are successful in simulating the CDC, does the code going from your adapter to the head unit have any pattern? What I mean is that by changing/rearranging the code pattern, would it be possible to open up another channel such as the DAB, MD, etc. If you are successful at that, then you can make a multi-input adapter. This would be well suited to many owners here as many want to connect their iPod, satellite radio, etc. and be able to select them from the HU. So for example, you can select CDC (CD CHGR) for those that have the Volvo CD Changer already installed, the DAB for those with satellite radio, MD for iPod.
Since the HU is capable of controlling and changing 10 discs, can you change the playlist on the iPod by turning the change disc knob and perhaps match the playlist with the disc number on the display? At least you can choose between 10 playlists on the iPod from the HU. Can you also change the iPod to shuffle play when you press the RND button?? I have so many ideas!!!
BTW, I think you have done something that the likes of Soundgate and Blitzsafe have failed to do. For that, I applaud your efforts!

Modified by R-Car at 2:15 AM 1-14-2005

Thanks!


Reverse engineering HU firmware might be possible, first I'll need the binary file of the firmware (where do I get this??
), find out what kind of processor is used in the HU and then run it through a disassembler - that's how the apple iPOD guys are doing it....(e.g. here: http://www.engadget.com/entry/1234000610023097/ ) it's a long road, though

I haven't fooled around with the protocol data yet, there is a special startup sequence, though, that might be used to address more devices on the bus. Further, the data only contains disc, track, time and some status (like play, pause, disc change, etc.) info, nothing more. I'm not sure whether the HU is capable of handling more than one device?
A more practical solution is one CD-C emulator which itself is capable of handling more audio inputs by use of a (digital controlled) audio mixer. The only problem is then how to select the audiosource. Might be done with the CD change knob... or some autosensing of the signal...

Yes, it should be possible to change playlists with the CD knob, but I haven't found this info in the iPOD protocol on the web. There is some info here http://www.maushammer.com/syst....html and here http://stud3.tuwien.ac.at/~e00....html on the iPOD protocol.
But that's all I could find. I am using for now only the basic remote protocol, so I can only use the remote buttons functionality.

Further, the iPOD has the capability to be controlled via the dock connector (see icelink, BMW solution, etc), which I haven't been able to get working. I am still using the top connector of the iPOD (where the remote attaches)

Strangely, I forgot to sniff the RND button... no problem... I have made a protocol sniffer for my project so I can easily check the protocol data on this. Again enabling shuffle on the iPOD has not yet been documented on the web.

Modified by mrg_Ed at 4:19 AM 1-14-2005

Modified by mrg_Ed at 4:34 PM 10-9-2006
 

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Re: FINALLY: CDC protocol on HU(-1205) has been reverse engineered! (mrg_Ed)

I don't know if you're doing this as a project for self interest or you actually plan to sell it. I know of at least two companies, besides Volvo, that will be marketing an iPod adapter for Volvo HU-xxx and the first one will be selling for less than US$100 due out in February. So you will face some competition if you plan to sell your adapter.
On the other hand, now that you have developed the tools and the knowledge of MELBUS, I think you're ready for your next challenge. Volvo markets a TV Tuner option for their cars in Europe and Japan. The TV tuner unit is also made by Melco and daisy chains itself behind the RTI unit. I, for one, would like to use the RTI screen not so much to watch TV but to watch DVD. By opening up the TV channel in the HU, I can connect a Pioneer DVD changer to the back of the RTI unit and play DVD on screen (when the car is not moving of course).
I have tried getting a TV Tuner from a dealer overseas but I have my reservations due to cost and compatibility. Even if I swallow the cost of the tuner, I'm not sure my head unit will recognize it. And, of course, there's no refund or support.
It would be awesome if you can get a hold of a Volvo with the RTI and TV option installed (car rental?) for you to do your magic on. At the same time, you can test your adapter with a car that has the RTI. Instead of competing with other iPod adapters, you can create your own market by making an adapter that will open up the TV channel on the HU. And its as simple as a little box with a DIN socket since the video goes through another connector.
Just some food for thought!

Modified by R-Car at 7:44 PM 1-14-2005
 

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Discussion Starter · #12 ·
Re: FINALLY: CDC protocol on HU(-1205) has been reverse engineered! (R-Car)

Hmm, interesting info, thanks for that, I didn't know..

The project is mainly self interest (and frustration, since there was no info on the web about the protocol or HU radios - the only thing I could ever find was a pin layout of the CD-C connector, which by the way was correct)

There were no suppliers anywhere that made a CD changer emulator for the HU-series and, as I noticed, there is still enough interest. I was desperate to connect my iPOD to the HU, so I took the challenge and started the project. It took me about 3/4 of a year to build all the stuff in my spare time. (I've built a logic analyser to analyse the signals, a protocol sniffer to get the data out, some PDA software to upload the data (I don't own a laptop), and some other supporting hardware.)
As I started it, I couldn't imagine that it was that much work! So, I am thinking of selling a couple to compensate for the invested time. (I don't need to be filthy rich
)

Anyway, since I don't have to charge development costs in the final product pricing (to keep a company running), I can sell for half of the price you mentioned, or even less... And if there are some DIY people that can handle a solder iron, I could only sell the programmed microcontroller. In that case you could have the emulator for less than US$30!

I am interested to know what functionality the companies offer to control the iPOD...

Your suggestions are quite interesting, though. Since I only own a HU-1205 with the navigation embedded, could you tell me more about the setup (what devices, what does it look like etc. - I don't have a clue)?
 

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Re: FINALLY: CDC protocol on HU(-1205) has been reverse engineered! (mrg_Ed)

I have little technical details on the iPod adapter coming to market besides preliminary pricing info and that it will be announced early February.
I have little details to provide you on the TV tuner since its not an available option here. However, I can certainly point you to a thread that peaked my interest. http://www.vvspy.com/w-agora4/...27365
Several people on Swedespeed including bylle have successfully tapped into the TV tuner. http://forums.swedespeed.com/z...age=1

The TV tuner is a box that fits on top of the RTI (DVD drive) in the trunk. The cable from the head unit (DIN8) goes to the RTI unit (DIN8), then from another connector on the RTI (DIN13) connects to TV tuner (DIN8). The CD Changer is the last on the chain since it only has one DIN8 connector.
 

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Discussion Starter · #14 ·
Re: FINALLY: CDC protocol on HU(-1205) has been reverse engineered! (R-Car)

Nice!
Since I know the Melbus protocol (at least for the CDC) I can understand what is said on the link you gave. I will very soon fiddle around with the data on the bus to see if I am able to 'fit in' an other device to the HU. I'll let you know...
 

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Re: FINALLY: CDC protocol on HU(-1205) has been reverse engineered! (mrg_Ed)

That will be most cool. Thanks for the effort. I will be anxiously waiting for another message: "FINALLY: TV protocol has been reverse engineered!"
 

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Discussion Starter · #16 ·
Re: FINALLY: CDC protocol on HU(-1205) has been reverse engineered! (MrTippy)

Thanks for the kind offer (laptop), I appreciate it.
Indeed too bad I am on this side, I would have liked to test the system on your configurations.

The CANBUS is quite well documented and I even have several articles of DIY building projects about it. This means that actual deciphering should not be necessary. CANBUS is mainly used to read out the cars computer as far as I know. It never catched my interest, however.
Should it? Is it the way to read/update the firmware for example?
 

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Discussion Starter · #17 ·
Re: FINALLY: CDC protocol on HU(-1205) has been reverse engineered! (mrg_Ed)

I just finished fiddling around with the data on the bus as I suggested earlier. I concentrated on the startup sequence, unfortunately without any positive results. I am afraid my HU simply doesn't support other devices. It might need a firmware upgrade or it might not be capable at all to get more devices on the bus (since there is no need to).

To tell you a little bit more about the startup seqence:
The HU sends out a series of bytes, which I think is a kind of device list. If the device is attached to the bus it responses to its 'device-id' by sending a response byte. So, what I did was try to respond to all existing device-id's. Nothing happened (besides the CD-C of course). This seems to be very similar as described in http://www.vvspy.com/w-agora4/...27365 as R-Car already found out.

So, I am kind of stuck. I do have a Melbus sniffer (as I mentioned before) but need the devices to sniff around....

It might be possible to get some of my sniffing electronics to you guys, so you can test and sniff around and send me the results back (the data is easily captured by an RS232 port on a laptop) to process.
If anyone is interested in this scenario, pls. let me know. However, it requires EE skills, like soldering and wiring a schematic to a PCB?


Besides: I made up my mind and decided to purchase a Dension icelink adapter. I really want to know what they are doing with the iPOD. They also make a very nice car cradle, which nicely fits in my car, I'm sure. I am planning to integrate their cradle into my CDC emulator (also). The cradle can be ordered separately and that should make a nice couple. I'll post some pics once installed...
 

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Re: FINALLY: CDC protocol on HU(-1205) has been reverse engineered! (mrg_Ed)

You're right, CANBUS is well documented but I'm sure Volvo would add their own twist to the protocol. I'd be leery about connecting anything foreign to CANBUS since the car's critical control systems (from ABS to airbags, etc) are on that bus.
I'm sure there is a way to access each of the 18+ control modules in the car including the AUM via CANBUS through the OBD port. One of the more creative application I've see is to display the status of the Valentine 1 radar detector through the information centre on the drivers information module (DIM). Someone markets such a box for BMW. But then, you would have to reverse engineer the protocol used by Valentine and Volvo. Too much trouble!
You're on the right track though, working on MELBUS. Just make sure you have a paypal account when you have the TV Tuner simulator box ready for sale.
 

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Re: FINALLY: CDC protocol on HU(-1205) has been reverse engineered! (mrg_Ed)

Dension does make a nice setup with their Ice-Link. They were relying on Soundgate to come with a Volvo adapter which never happened.
Does anyone on the board have a S60/V70 with the RTI and TV Tuner option willing to drive over to mrg_Ed's place for an afternoon??
 
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