M-Bus CD changer adapter for car pc integration

**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

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

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: Alpine Ai-Net to RS232 interface. 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