Factory Stereo BUS specifications

dgeist · **Posted:** Thu Apr 27, 2006 12:06 pm

I have a 2005 Limited CRD with the in-dash 6-disc changer and Sirius. I'm interested in developing a car-pc interface (line-in plus rs-232 or USB, probably) and I've been trying to get information on what BUS protocol the Mopar stereos use to talk to peripherals. Anyone have this info?

Dan

billforde · **Posted:** Thu Apr 27, 2006 2:13 pm

I am not sure what the protocol that chrysler uses, but you can get a P.I.E interface that will convert it to sony (s-link) or alpine (ai-net), which you can find the specs for.

dgeist · **Posted:** Thu Apr 27, 2006 2:32 pm

Forgive the ignorance, but "P.I.E"? Is that a manufacturer or an acronym for a description of the device?

billforde · **Posted:** Thu Apr 27, 2006 2:54 pm

My bad, i should have posted some links.
http://www.pie.net/store/index.cfm?Action=ViewCategory&Category=100
http://www.brian-patti.com/s-link/ Unfortunately most of the links here are dead.

billforde · **Posted:** Thu Apr 27, 2006 5:10 pm

The other protocol is Unilink (forgot to post that one).
http://cleggy.umcus.org/index.htm

CaKJFreedom · **Posted:** Thu Apr 27, 2006 6:15 pm

Off topic: excellent avatar choice!

dgeist · **Posted:** Thu Apr 27, 2006 6:26 pm

Assuming you're talking to me, then thank you. It's the fraggle that most closely resembles my personality, even if it doesn't resemble me visually...

CaKJFreedom · **Posted:** Thu Apr 27, 2006 6:57 pm

Good thing, you'd have some crazy hair!

dgeist · **Posted:** Thu Apr 27, 2006 7:02 pm

Nah, I look more like this.

I'm only a fraggle at heart.

unixxx · **Posted:** Sun Apr 30, 2006 1:27 am

degeist, the factory radio communicates with Sirius via a "PCI" bus which is a superset of OBD-II. This is the same bus that travels thoughout the entire car and the same bus that the OBD-II port directly taps into. The bus uses the J1850 VPW communication format. You can grab a chip from Elm Electronics (ELM327) which should allow you to read/write to the bus via serial port. I'm working on this circuit right now for Sirius integration with my car pc. I still don't know if the inerface will actually end up working though as documentation is kind of few and far between.

Skymech · **Posted:** Mon May 01, 2006 6:31 pm

CaKJFreedom wrote:

Off topic: excellent avatar choice!

If i remember thats "Traveling Mat" He wrote the Kids back at the "rock" about all the places he had been to in his travels.

dgeist · **Posted:** Tue May 02, 2006 11:22 am

unixxx wrote:

degeist, the factory radio communicates with Sirius via a "PCI" bus which is a superset of OBD-II. This is the same bus that travels thoughout the entire car and the same bus that the OBD-II port directly taps into. The bus uses the J1850 VPW communication format. You can grab a chip from Elm Electronics (ELM327) which should allow you to read/write to the bus via serial port. I'm working on this circuit right now for Sirius integration with my car pc. I still don't know if the inerface will actually end up working though as documentation is kind of few and far between.

Sounds interesting. I was thinking of possibly a switching unit under the dash, etc, to direct control and audio pins between the sirius and serial/PCM line signals.

If you come up with something, I'd love to help you test, etc. I can hack the PC C-code for serial control, but my wife is more the EE type, she could probably help me prototype a board.

Dan

unixxx · **Posted:** Sat Oct 28, 2006 8:03 pm

Dan,

I managed to get my ELM327 interface working using the identical schematic out of the ELM datasheet. I spent over four hours troubleshooting it and the problem ended up being that the socket was loose causing the RTS pin to float instead of being brought high. I tested it out by grabbing the engine coolant temperature which the Libby reported to be 68 degrees fahrenheit, which seemed about right. I also had it stream current PCI bus data that maybe I can decode later. If you have any questions on it let me know.

unixxx · **Posted:** Tue Oct 31, 2006 1:03 am

Yesterday I managed to sniff the PCI bus for the steering wheel audio control "packets." Hopefully soon I'll have some software written to monitor the bus for these packets and use them to control the volume, etc on my car PC.

dirtykj · **Posted:** Tue Oct 31, 2006 1:48 pm

This should be stickied --- assuming you guys can reverse-engineer the protocol and can document it.

Factory Stereo BUS specifications

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