M-Bus CD changer adapter for car pc integration - Page 2

MatrixPC · 12-20-2004, 04:13 PM

I bought an Alpine M-bus adapter (I think this is the model KCM-122B) from Crutchfield once and returned it because that adapter is not work with my HU.
I search the net and the only solution I found what from one of the link from this site http://joerg.hohensohn.bei.t-online.de/mbus/, but I don't really understand the whole circuit.
Searching this board there are some long old member stated that using a resistor (3.3K) may trick the HU to "think" that the changer is connected and thus enable the CDC port. I just don't know where to put the resistor.
Some info I also found that the Honda/Acura HU also using the same Alpine M-bus for CDC and some stated that use 6V instead of 3.3K resistor. They just didn't stated that to which pin of the 8 pins (Data+, Data-, IGN/ACC, ...). Before I found solid information, I don't want to blew up the fantastic HU.

Again, before the HU can talk to the CDC, the HU must "knows" that the CDC is connected. I need to know this part.

jbors · 12-20-2004, 07:18 PM

In order to fool the HU you have to send the special sequence to it.
Crutchfield has aux adapters that fools most of the M-Bus HU but not all.
Joerg project does that fooling in PIC code. No PC involved.
I prefer the PC solution as it is easily upgreadable. So it can tweak it if the default driver does not work.

lanman1 · 12-20-2004, 07:24 PM

Quote: Originally Posted by jbors

My schematics not finished yet. I will release it all on mid Jan. It will be M-Bus, AI-NET USB adapter. Sorry don't want to mess up with serial. It will be available either as PCB+parts so you can solder it or as a finished product. Of course all the schematics will be available for public. I estimate the fully functional assembled device for ~39 by end of Jan. May be little cheaper...
The link above is the good place to start but my schematics is different.

Sweet! Let us know what we can do to help.

MatrixPC · 12-21-2004, 12:05 PM

Quote: Originally Posted by jbors

In order to fool the HU you have to send the special sequence to it.
Crutchfield has aux adapters that fools most of the M-Bus HU but not all.
Joerg project does that fooling in PIC code. No PC involved.
I prefer the PC solution as it is easily upgreadable. So it can tweak it if the default driver does not work.

Dam.... back to square one.

Thankanyway.

jbors · 12-24-2004, 02:04 AM

Quote: Originally Posted by MatrixPC

Dam.... back to square one.

Just let me know _exactly_ what you need. It would be much easier to answer that way. Probably I'm missing something.

MatrixPC · 12-27-2004, 02:02 PM

My HU is an older Alpine cassette with CD changer control M-bus (TDM 7534 10 years old) installed in my Supra. Prior to CarPC thinggy, I have a CD changer S600 connect to the HU. After CarPC installed, I use tape adapter for computer sound to the HU. That CD changer was never been use since.
I took the changer out and install in my Honda Accord original HU via one of the Adapter (PIE) I bought from Cruchfield. I also bought an Alpine M-bus to Aux adapter, but this thing doesn't work with the HU because the HU is OLD. To use this adapter, the HU must have an option in the setup to enable the sound in put from that adapter. This HU doesn't. I have to return it.

After I search the internet, I found some info on the Honda/Acura(older Honda/Acura use the same CD changer with switch Left/Right audio channel) forum saying that by using 3kohm resistor or 6V to foul the HU into "thinking" that the CD changer is connect to the HU and thus enable the sound from the changer port. So that when I hit the CD button on the HU, the HU switch to CD mode and the sound is feed from the PC.

Now what I don't know is how this 3Kohm resistor is connect to. Power Supply and DataBus? or ... ?????
CD changer connecto Pin out

The HU is similar to this.

jbors · 01-05-2005, 10:50 PM

Hmm,
All the data from/to MBus goes through Data Bus connector, so you should connect your 3kOm resistor between that line and +12V( Battery ? ).
Personally I don't believe that putting 6V onto data bus line will do the trick. All my headunits require certain packets to be returned every 1/2 second.
Hope this helps.

jbors · 01-05-2005, 10:53 PM

Just to give a heads up on adapter's development.
I ordered the PCb board and it came 2 days ago... Here are the pics.

I'm still waiting for the parts to come for a challenge to begin.
Will keep you posted.

AdReNaLiN · 01-06-2005, 12:26 AM

I am VERY interested in the development of this. Anything I can contribute to the completion of this device, please let me know.

Will the device allow owners of Alpine Ai-Net headunits to control a CarPC with the headunit therefore for music playback this would eliminate the need for a screen mounted to the dash?

jbors · 01-06-2005, 01:52 AM

My preliminary tests shows that Ai-NET can be compatible with MBus. Some extended features needs more investigation but in general it will work just fine.

Dominik · 01-06-2005, 07:00 AM

In your first post you mentioned that it should accept commands from any head unit through an adapter. Any chance i can use my Kenwood KDC9016 headunit for this?

If not, This kind of thing would make me consider selling my headunit to buy an alpine headunit!!! Cant wait to hear how it goes...

AdReNaLiN · 01-06-2005, 09:47 AM

I have a query as to what the head unit will display when it is controlling the carpc?

What will happen when you want to change from MP3 playback to a DVD or Video playback? What about when you switch to GPS?

Also, like I said before, can I contribute in any way to the development of this device?

jbors · 01-06-2005, 10:43 AM

Quote: Originally Posted by Dominik

In your first post you mentioned that it should accept commands from any head unit through an adapter. Any chance i can use my Kenwood KDC9016 headunit for this?

If you can find which CDC can be connected to this HU it will tell you.
Right now my device will understand only MBus and AI-NET.

jbors · 01-06-2005, 10:46 AM

Quote: Originally Posted by AdReNaLiN

I have a query as to what the head unit will display when it is controlling the carpc?

What will happen when you want to change from MP3 playback to a DVD or Video playback? What about when you switch to GPS?

Also, like I said before, can I contribute in any way to the development of this device?

You see that MBus HU has very limited set of commands, so the software may hardcode that DVD is track 7 and GPS is track 8 or something. For AI-NET I think it will be possible to display graphical info instead. I will talk to it once I got AI-NET protocol diagrams.

If you want to help, just start from AI-NET hacking, commands and features supported would be the thing we all need.

AdReNaLiN · 01-06-2005, 11:23 AM

So do you currently have an Ai-Net headunit or a M-Bus headunit?

I also found this thread: http://www.mp3car.com/vbulletin/general-hardware-discussion/19108-alpine-ai-net-rs232-interface.html in my searching on this topic some time ago - I followed it through to his website and I emailed him with no reply.

This topic from the website also may be of interest: http://www.intravention.co.uk/forum/viewtopic.php?t=6

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