MP3 players emulating CD changers?

**cddaly** · 01-09-2001, 10:14 AM

Hi Guys - I am wondering if anyone has wired their MP3 player to emulate a CD changer. I looked at a couple of CD changers (one a Nissan OEM made by Clarion and an aftermarket Alpine) and they both have serial communications going between the radio and the CD changer to switch tracks, display track time, etc. Has anybody done this? Figured out the command format? Any help would be appreciated. Thanks, Dave Daly

**Richard91** · 01-19-2001, 06:39 PM

http://www.phatnoise.com/

**mccleanp** · 01-22-2001, 12:48 PM

I too would like to emulate a CD changer, at the very least it would solve the problem of getting nice buttons and a display.

The Phatbox looks pretty good, and credit certainly does have to go to the designers. But most people on this site are interested in engineering their own solution, not just lifting an after-market device.

Does anyone have any info on the communications specification between CD changers and head units. I have a Kenwood head unit, so Kenwood info would be of most use to me. I had a look around the phatbox web site, but there were no technical details.

I am fairly confident, that given the pinouts and protocol details of the interface, I could come up with the necessary hardware and software.

Regards,
Paul

**gizmomkr** · 01-22-2001, 04:17 PM

Im working on trying to dig up some info.. I also have a kenwood head unit - KDC-515S

I wrote kenwood a leter, I doubt I will hear back...

**killfiend** · 02-01-2001, 11:25 PM

i was just about to start a topic about this. i just got a jvc, and its gotta be possible.

**gizmomkr** · 02-02-2001, 09:16 AM

well, its definately possible, but geting that interface info from the Mfgr is going to be dificult, might even require licensing....fees...Etc.
Im not exactly sure

So far, Kenwood has been bad with responding to my requests.

**jjohnson** · 02-02-2001, 12:49 PM

I'm actually working on this right now, for a commercial product ( www.m2pc.com ). I am getting a Kenwood CD Changer and plan on using a scope and logic probe/analyzer to "peek" at the signals going to <-> from the CD changer and head unit. I plan on making a PIC module that connects to the parallel or serial port and talks to the head unit, so the car PC looks like a CD changer to the head unit.

All I know at this point is:

- The protocols are serial
- Each MFR has their own standard, so I would potentially need to "hack" each brand to discover its protocol.
- There are audio signal lines in the same cable for getting audio to the head unit -- useful for units with no line in or aux in jacks!

I'll keep y'all posted...

**gizmomkr** · 02-02-2001, 03:14 PM

I would deffinately buy that pic if/when you made one.

I have a scope, but am not well versed in using them. I also have access to a serial line data analyzer at work. let me know if there is anything I can do to help.

**r0cket-** · 02-02-2001, 08:19 PM

I've thought about this quite a bit too, but, lacking the resources, I haven't really done anything about it. I think it might be nice to have the elapsed time and track/playlist number of the current song displayed on the head unit, and use a character LCD for directory browsing and whatnot. Free up a little space on the LCD, and have the time display where you would normally expect it. But, using just the head unit for all that (like the phat-whatever.com guys are doing) seems pretty lame, not to mention ackward.

**lifter** · 02-03-2001, 07:35 AM

I have an old Alpine CD changer/head unit, and I have the pinout somewhere. If anyone really needs it just email me and I'll dig it up the link. Supposedly, the Alpine pinout is identical to the stock Acura Integra (not sure which years) changer. But like JJ said, 3 of the pins are regular old analog audio signals, one is power (12V I think), one is ground, and there is a bus data send and recieve. 9 pins total, I think - same as a serial port.