Recording CAN Bus data in an Audi A4

Hi everyone, I'm currently working on replacing the old Audi Concert head unit in my 2009 Audi A4 B8 with a Raspberry Pi running Open Auto Pro. I wanted to record all the CAN signals that are being sent and received by the Audi Concert radio.
I'm using a Raspberry Pi 3 along with a CarPiHAT, an expansion board for the Pi that includes an MCP2515 chip for CAN communication. I've connected the board to the CAN-L and CAN-H lines (which are normally connected to the radio) using jumper cables. On the Pi, I've configured the `can0` interface and started `candump`. So far, I haven't been able to receive anything (meaningful). I've also already tried the CAN connections in the OBD2 connector, but without success.

Does anyone perhaps have an idea what I'm doing wrong? I've already read that VW/Audi CAN systems are tricky .

Hi! I'm not familiar with the Audi Concert system, but I had the MMI3G in my 2009 A6 4F. Everything was connected via the MOST bus (Gateway > Headunit > DAB tuner > Bose > Gateway). All multimedia data was transmitted through this bus. This means that no data is available on the CAN bus.

It's possible that only the radio is running on the multimedia CAN bus, in which case you'll need to rely on that.

Hey Zampan0
I believe the MOST bus is only available with MMI systems. My Audi Concert only has the positive and negative terminals, as well as connections for the speakers, AUX jack, microphone, and the two CAN bus lines. Everything has to run through those connections. From the inputs of the steering wheel controls to the oil level.
I think the problem is that I first need to send the correct request to the CAN gateway behind the radio in order to receive the data I want. Unfortunately, I have no idea what he's trying to hear.

Okay, then it should be easier!
In any case, all the "relevant data" is available on the CAN bus where the concert is connected, so there's no need for a request.
And no, not all data, from the steering wheel controls to the oil pressure, is being transmitted through it!

The gateway provides 4 or 5 CAN buses (plus MOST), depending on the configuration.
Depending on the software and encoding, relevant data is passed from one CAN (Controller Area Network) node to another (routing table).

I'm not sure if component protection was an issue during the concert, as that can sometimes be a very complex matter.

Zampan0

Code:

can0 1503FAFF [2] remote request can0 71B [8] DA 13 2A 7D 31 BD FF 6D can0 06FEC488 [8] FF E9 DF A8 EF 6E EE DD

And no, not all data, from the steering wheel controls to the oil pressure, goes through it!

Quote:

"By 'all data,' I meant the information that is available through the radio system. For example, you can display the oil pressure, adjust settings from the instrument cluster, and see how the automatic climate control is configured. To name just a few key examples. What led me to my assumption about the request is this sequence of frames that I was eventually able to capture:

"I receive that signal as soon as I connect the jumper cables to the CAN connectors. However, nothing else happens after that. Could it be that this is some kind of beacon from the gateway, and I need to respond to it before I can receive any data?" Unfortunately, I can't really make sense of it with just a few bytes.

I once tried setting it up with a VW Discover Pro, and it constantly received data from the gateway.

"Ignition on" is sent every 1000 milliseconds (0x3C0).

Please press the volume up or down button on the steering wheel during the log recording.

Quieter -> press 0x5BF 0x11 0x00 0x01 0x40, release 0x5BF 0x00 0x00 0x01 0x40.

Loud -> 0x5BF 0x10 0x00 0x01 0x40 release 0x5BF 0x00 0x00 0x01 0x40

I no longer have any current data because I have replaced all vehicles from the VW Group .

Hello,

If I remember correctly, the gateway should be sending data continuously.

Best regards, Rainer.

I actually thought the same thing, but I'm still getting no response. I've also read a few times in this interior/comfort-related CAN forum that there seems to be a kind of "registration" process for the radio.

https://www.canhack.de/en/viewtopic.php?t=35
and
https://www.canhack.de/en/viewtopic.php?t=988

My theory is still that you need to send something into the CAN bus before you can receive anything. Is there any truth to this, or am I completely misunderstanding everything?