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CAN bus setup problem


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I am setting up a BMW e46 instrument panel through the Can bus. I get the RPM, temp and several warning lights to work (cruise, EML, engine light and high temp). ( FYI: the RPM and temp work with the Mini mode also)

Cruise, EML and engine light is on the same ID 1349, and in the same byte 0. But use different bits of course.

If I make 1 "frame" and test them 1 at a time they work. But If I add a second "frame" on the user stream for a second light there are problems. It seems like frame 2 takes priority because this show 95% of the time but there is sometimes some rapid flicking of the first lamp also. They never light togheter it is just one at a time, but it is very rapid.

Is this me using it wrong or is there a firmware error???

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The problem here is that you are sending (in very quick succession) two frames with the same CAN ID. So the dash receives one with the light on, then one with it off, but the other light on etc...

You need to put everything you wish to transmit on one particular CAN ID into a single frame so that the dash periodically receives only one CAN frame containing the state of all of its inputs.

When trying to replicate OEM can modes, you will never (actually very rarely) have a stream with more than one frame in it. Multi-frame streams are only used by aftermarket devices such as loggers.

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Okay thanks.

I had a feeling it was user error, I am pretty new to CAN bus setup. I was so hung up on the Frames, that I did not try the obvious thing to add another parameter.. I thought it was one frame for each parameter, so thanks for the info. :). Will do some more testing when I get home again.

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