CAN-BUS Car mediacenter

Project MPi3 – New housing and published all source code

Previous: Display additional data


Hey there, I finally managed to upload source files for my Project!

Program at GitHub

Housing at thingiverse

The program currently listens for the previously mentioned diagnostic data. The Requests are send outside the program. I will change that when i figure out how to get the data without activly asking for them. Just by observing the bus.

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As you can see above, there is also a housing for the raspberry and the other components. The system is now installed hidden in my car, directly connected to the entertainment bus and the aux-in of the headunit.

The Connection is made with a 15-pin d-sub connector as follows:


The audio in connects to the audio out of my tv receiver, the 12V are from the power source for the interrior lighting. This line will be activated when the car gets unlocked and stays active for about 30 minutes after locking the car. So the components won’t stay active all the time and drain my battery but will be available as soon as I enter the car.

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My 12V USB adapter has two USB-ports. One was dissoldered and connected directly to the raspberry solder-pads PP1 and PP3. The other one is connected to my 4G-Router outside of the housing.

The Soundcard is also directly soldered to the Raspberry PP7 (+5V), PP42 (D-), PP45 (D+) and PP40 (GND).


For now I am really satisfied with this build although it is not yet ready. But becaus of that, the next update might still take a lot of time. Sorry for that…


Next: Capture the values without activly asking, upload the values and create nice graphs with them.

CAN-BUS Car mediacenter

Project MPi3 – Display additional Data

Previous: Fully working prototyle


With a controller connected to my Vehicles CAN-bus, I don’t want to limit the use of it to song-title and music controls. So I started to look for some more interesting values to get from the bus.
Sadly the “MS-CAN” (entertainment bus), which I am connected to cause of the info display, doesn’t allow communication to the ECU (also, this factprevents me from messing with the engine or other critical components).

The components connected to the bus do have some interresting informations and GM built a diagnostic protocol that lets you ask the controller for the actual values. This leads to the folling data:

248 # 06 AA 01 01 07 10 11 - Ask the A/C controller (0x0248) for measuringblocks 01, 07, 10 and 11
548 # 01 03 A5 00 00 01 9C 00 - 01: 0x03A5: Solar sensor: 4.665V - 0x019C: Indoor temp sensor: 2.06V
548 # 07 00 90 04 3D FE 70 00 - 07: 0x90: Voltage: 14.4V
548 # 10 00 91 02 B2 03 1E 96 - 10: 0x0091: Out-temp: 14.5°C - 0x02B2: Engine temp: 69.0°C
548 # 11 08 ED 00 30 01 FE 23 - 11: 0x08ED: RPM: 2285 - 0x30: Speed: 48 km/h - 0x23: LED: 35%

The described values are only the ones that I already figured out.

My software now listens for this data on the bus and writes the values on the display.

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The displaymode can be switched with the number keys on the headunit (which are also unused in aux mode)


Next: New housing and published all souce code

CAN-BUS Car mediacenter

Project MPi3 – Fully working prototype

Previous: Music-Player gets CAN-BUS!


Since a very long break caused by many other projects going on, here is now another update.

The System is now functional and works pretty well.
Most important change: The projects now has a Name: “MiP3” (Raspberry Pi based MP3 Player… got it? Yeah, I know…)
Before the technical details, here directly the usage:

There are four play modes:
– My music
– My girlfriends music
– Carpool (society-compatible) music
– Audio from TV-Receiver (DVB-T – The non-american version of ATSC)

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The playlist is switched by pressing the (in AUX-Mode unused) steeringwheel-down button. Holding the button will activate the TV-audio-mode.
By pushing the up button, the song will be skipped and the skip will be marked in the database. Holding up will delete the current song from the actual playlist.
New music will be added to all playlists and stays there until it is removed. So in the beginning, all music was played in all modes. But after two months now, the playmodes fit verry well. I currently have about 20GB of music installed.
There is no chance to play one particular song, this is by design because I wanted to have it more “radio-like” where I can just take slight influence on the music.

When the TV-audio is activated, the sound from the audio-in of the USB-Soundcard will be played with “alsaloop”.


Next: Display additional data



CAN-BUS Car mediacenter Electronic upgrades

Music-Player gets CAN-BUS!

Lets’s get deeper in the car’s electronics

My XBMC-Mediacenter works pretty well. But the only way to skip a song is the I/R remote placed in my armrest and to see what song is playing, I need to switch the whole display to mediacenter mode.
Because I always wanted to take a closer look at the CAN-BUS in my opel astra, I decided to give the music player another update.

So I ordered a MCP2515 / MCP2551 CAN-BUS interface for a raspberry pi and started to scan the bus.

The opel astra h (2004-2010) has the following busses:

  • SW-CAN (SingleWire) 33.3 kbps also known as “GMLAN”
  • MS-CAN (MidSpeed) 95.0 kbps
  • HS-CAN (HighSpeed) 500 kbps

The car body bus

The first was to capture some “base noise” with the bus awake and the ignition off. Then I performed some actions like pressing buttons, locking/unlocking the car etc.
That capture could be compared to the base noise to identify the messages only send in that capture. That gave me some results:


This means that when I send 160#0340C803, followd by 160#0300C803, the car locks! This point was a huge milestone!

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The entertainment bus

What I really was interested on was the MS-CAN with the unusual 95 kbps!
So I did the same as above and found what I wanted:

206 # 01 91 00 - Steering Remote UP
206 # 01 92 00 - Steering Remote Down

I also found the outdoor temperature:

683 # 46 01 XX where the temp in celsius is XX/2-40 so 0x00 is -20.0°C and 0x76 is 19.0°C.

But the really cool data goes to the display:

6C1 # 10 2E C0 00 2B 03 01 01
6C1 # 21 00 20 23 03 00 41 00
6C1 # 22 75 00 78 10 0A 00 1B
6C1 # 23 00 5B 00 66 00 53 00
6C1 # 24 5F 00 67 00 6D 00 41
6C1 # 25 00 75 00 78 11 01 00
6C1 # 26 20 12 01 00 20 01 00

The first byte of the packet identifies a multi-packet message. It starts with 0x10, than follows 0x2X where X increments from 1 to F. So after 0x2F comes 0x20, 0x21…
The second Byte of the first packet is the number in Bytes. The last packet is always 8 Byte long but the rest is ignored (these are either filled with 0x00 or the same then the previous package).
Than are two byte of command or mode. This is 0x4000, 0xC000, 0x5000 or 0xA000. Don’t know what that means… Than comes the size and type of the following container. Type 0x03 seems to update the main screen.
Now follow some strings, starting with an ID (here 0x01,0x10,0x11 and 0x12), the number of characters and the characters in UTF-16 (where only very vew unicode-chars are supported but that comes in the next post).

That’s all…

This is a schematic view of the above packet:

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With that knowledge, I generated my own packet:

6C1 # 10 54 C0 00 51 03 01 01 - 84 Bytes, mode 0xC000, 81 Bytes payload, type 0x03, id 0x01, 1 char
6C1 # 21 00 20 02 03 00 41 00 - Whitespace, id 0x02, A
6C1 # 22 75 00 78 10 07 00 48 - u x, mode 0x10, 7 chars, H
6C1 # 23 00 61 00 63 00 6B 00 - a, c, k
6C1 # 24 65 00 64 00 21 11 0C - e, d, !, id 0x11, 12 chars
6C1 # 25 00 76 00 69 00 73 00 - v, i, s
6C1 # 26 69 00 74 00 20 00 6A - i, t, Whitespace, j
6C1 # 27 00 62 00 30 00 2E 00 - b, 0, .
6C1 # 28 64 00 65 12 0C 00 68 - d, e, id 0x12, 12 chars, h
6C1 # 29 00 61 00 63 00 6B 00 - a, c, k
6C1 # 2A 61 00 64 00 61 00 79 - a, d, a, y
6C1 # 2B 00 2E 00 63 00 6F 00 - ., c. o
6C1 # 2C 6D 00 00 00 00 00 00 - m

And what happened? This:

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Next: Fully working prototype