Thread: M-Bus CD changer adapter for car pc integration

I want some how to use the CD changer (M-BUS) port for the aux input on my Alpine HU. There is no way (i know of ) doing it without a CD changer. Most newer M-bus HU has a mute line. Ground the mute line -> enable aux input thru changer port. This HU doesn't do that. It's an old M-bus HU (pre 95 model).
jbor do you have any idea?

http://joerg.hohensohn.bei.t-online.de/mbus/

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.

Originally Posted by MatrixPC

This HU doesn't do that. It's an old M-bus HU (pre 95 model).
jbor do you have any idea?

I would recommend google:
http://www.google.com/search?hl=en&l...er&btnG=Search
If you don't want control over the PC from your HU it will fit you just right.

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.

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.

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.

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.

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.