[info] CAN bus: BMW instrument cluster

[AndreyB]

It's too damn dark & cold outside, so I'll distract myself with some CAN bus fun. 2002 BMW 330 instrument cluster was $57 shipped from car-part.com.

Wiring diagram:


The CAN shield is http://www.wvshare.com/product/SN65HVD230-CAN-Board.htm based on http://www.ti.com/product/sn65hvd230

More on BMW e46 Can bus

[AndreyB]

The cluster has arrived and it took me 'only' two hours to figure out that it wants +12 on three wires in order to start sending out CAN messages.
So, "BATTERY" + "IGN (START/RUN)" + "IGN (ACCY/RUN/START)" powered (and obviously GND) got me a constant flow of CAN messages. Here they are on the logic analyzer (that white box in the top-right corner)

[AndreyB]

With a hint from ChibiOS forum I have received my first CAN message! ARBID 0x613 is one of the cluster status messages. Big day for our CAN subsystem

[AndreyB]

That's a miracle. This cluster has arrived yesterday and today I am controlling it?!


I hope one day we will control injectors via CAN.

[jedediah_frey]

I hope one day we will control injectors via CAN.

Unfortunately CAN isn't deterministic (FlexRay will be) so CAN is best used for communication of non-realtime information.

[AndreyB]

Turned out e46 has a CAN message for speed, but the instrument cluster does not use it! Speedometer works via a PWM on a dedicated wire fed from some other block somewhere else. Tach an temperature is controlled by CAN. With 30 wires coming to the cluster it looks like the e46 is an intermediate technology mixing some CAN with some analog.

For example Mercedes W220 instrument cluster has only 11 wires connected to it - but no one has bothered to reverse-engineer the protocol yet.

Anyway, this was interesting experience and e46 cluster goes to eBay

[AndreyB]

Since PCI is still pending and plans B and C have failed

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