Radio on or steering wheel controls via CAN

Hello everyone,

Has anyone managed to send data via CAN bus to a car radio and achieve a specific result?
I have a Raspberry Pi with an MCP2515 transceiver connected to the CAN 1 port of an Android radio, and I'm trying to send data to it, but it's not working.
There are now many possible causes for the problem, including wiring, kbps, and messages.
I can adjust the vehicle settings on the radio, and it also has CAN1 and CAN2 interfaces.
CAN1 is likely the main bus, while CAN2 might be the multimedia bus, or perhaps it's the other way around.
The question is, for example, whether the ignition and lights are only connected to the main bus, or if they are also connected to the multimedia bus.
The most interesting aspect would be ignition and lighting – which vehicle type/bus/kBps/message has someone successfully used for that before?
The steering wheel buttons, likely on bus 2, would also be something to check. That would tell me if it even works. For example, the CAN transceiver only has 5 volts; is that enough power for the car accessories at the other end?
Here's the translation:

'With the radio, you can program the steering wheel buttons. I'm now wondering how that works. Does the radio only receive messages through the multimedia bus? When programming, does the radio simply receive the message that corresponds to the button press? I thought many messages were transmitted through the bus, so how does the radio know which message to use during the programming process?' Does it already know an ID range to filter, or does it check which new or changed messages are acyclic? However, if other messages are also acyclic at times or change, it might be difficult to distinguish them.

Hello chipy,

What kind of car do you have, and what kind of radio?

What kind of data are you sending to your radio?

CAN-Bus uses approximately 5V. In the bus system, IDs and frames are constantly being sent, and these vary.

The devices identify whether a frame is intended for them based on the ID.

It's a kind of broadcasting. So, all the data is simply broadcast, and the receiving device retrieves what it needs based on the ID.

The best way to start is to connect your Raspberry Pi to your CAN bus and sniff the data using Wireshark. You need to know which ID the radio is using. I think everyone who starts working with CAN bus encounters this problem. Where can I find documentation that describes the IDs? That's why the great CAN interface exists (located in the top left corner of this page), which makes it possible to efficiently decode the data.

I have an Android radio where I can set the vehicle type.

I found an 'Ignition On Message' for Mercedes W2xy in this forum.

001# 04 00 00 00 00 00 00 00

I tried that approach. If it's actually the number 1, it could be the same ID for Mercedes every time.

I also have a Mercedes-Benz A-Class W169. For testing, I can tune the radio to settings for various common car makes and models, such as BENZ (Smart).

chipy wrote:

I have an Android radio where I can set the vehicle type. I found an "Ignition On Message" for Mercedes W2xy in this forum. 001# 04 00 00 00 00 00 00 00 I tried that approach. If it's actually the number 1, it could be the same ID for Mercedes every time. I otherwise have a Mercedes-Benz A-Class W169, and for testing, I can adjust the radio to settings for various common vehicles, such as BENZ (Smart).

Unfortunately, since I still don't know what kind of radio you have, I can't help you.

"It definitely sounds like a Chinese radio to me. Since Smart has several models, and not every message in the CAN bus is the same, what you're planning won't work. The Mercedes W200 series is huge, so there will be extreme differences in the IDs." I would suggest looking into VW forums, as the IDs are often the same there, and there's more information available online.

I also don't have a recording of "ignition on," as that information isn't available in the CAN system either!

Furthermore, I don't want to send anything, as the vehicle identification number (VIN) is also found in the log. I recommend you create a connector and simply perform a CAN dump on a vehicle that has CAN communication accessible through the OBD port.

It's best to figure out what ID the radio expects when, for example, a Mercedes (SMART) profile is selected. You say it's an Android, so rooting... somewhere there must be a definition of which profile expects which ID.

"Or try searching the internet for a complete list of IDs, preferably from a VAG vehicle." Then, adjust your radio accordingly.

You might be experiencing the same problem I am right now (I can't send anything).

Unfortunately, since I still don't know what kind of radio you have, I can't help you.

Since there are multiple models of Smart cars, and not every message in the CAN bus is the same, what you're planning won't work. The W200 series from Mercedes is huge, so there will be extreme differences in the IDs.

Regarding the radio, as I mentioned, I can adjust the settings for the car, so it's irrelevant in this case.
I don't understand the question. Do you know all the different types of radios, or do you know what you need to send to your radio for it to turn on?

I often hear that things are extremely different, but are you sure that this applies to such basic things as starting the engine?

Is there an ID 001# in your logs that looks similar to the one I mentioned?

chipy wrote:

Regarding the radio, as I mentioned, I can adjust the settings for the car, so it's irrelevant in this case. I don't understand the question, do you know all the possible radios?

Because I might want to look for a document about the expected IDs.
Furthermore, you can see what the CAN bus connections are actually used for.
It's a Chinese radio, and I don't know what the radio's developer was thinking by trying to cram the entire W2xy series into one device! There must be some documentation for this. A W202 does not have a CAN bus... neither does the older W210...

chipy wrote:

I often hear that everything is extremely different, are you sure that this is also the case for such basic things like starting the engine?

Yes, 99.9% certain! There might be some similarities here and there, of course, but not in the way you suspect.

chipy wrote:

Is there an ID 001#

in your logs that looks similar to the one I mentioned?

"I don't have any entries with an ID like 001 or similar in my logs."

Because I might want to look for a document about the expected IDs.
Furthermore, you can see what the CAN-Bus connectors are actually for.
In the past, there was a wire that, when connected, would turn the radio on and off.
Now it's being done via CAN, and the radio only receives constant power.
There need to be signals like 'ignition on,' 'engine started,' etc., which the radio can respond to.
And then, turn on the light where the keyboard backlight comes on.
Third-party radios also need to respond to these announcements.
Such news is definitely going to be on the main bus.
Then there might be a secondary control unit with fewer functions, where things like steering wheel buttons are located. It would make sense for functions like 'start/stop engine' and 'lights on/off' to be included there, but perhaps not.
Have you observed during your tests when the notifications appear regarding the bus, specifically from the moment the door unlocks, the key is inserted, and the ignition is turned?
When should I no longer use it, should I take the key out or lock it up after a while?

I haven't tested that specific functionality yet, but I've noticed that my bus system only transmits frames relevant to the engine, speedometer, ABS, ESP, and central locking. I think your radio is likely activated through the multimedia CAN bus. There are these CAN interfaces available that are needed to integrate older radios into newer vehicles. Perhaps you'll find something there, because these devices must also receive an ID, which triggers the interface to switch certain voltages.

In multimedia applications, it is quite possible that standardized frames and IDs are used.

It's possible that the large number of different equipment options also leads to many variations in the CAN bus system, and that similar components might still share the same ID.