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  #11  
Old 09-11-2021, 01:17 PM
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Quote:
Originally Posted by lkv0315 View Post
So what exactly do you mean by terminated?
There are 120 ohm termination resistors at each end of the bus, see https://www.kmpdrivetrain.com/paddle...-tips-can-bus/. I believe the E53 has them at the cluster and DSC.
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  #12  
Old 09-11-2021, 01:19 PM
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Originally Posted by lkv0315 View Post
Iím using a CAN HAT called the waveshare RS485
I posted saying that won't work then I read about it. The name is deceiving - RS485 is not the same as CAN, but looks like that device does both.
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  #13  
Old 09-11-2021, 01:26 PM
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I don't think the BMW CAN bus uses RS485 which could be part of your problem. RS485 is directional so the software will need to take that into account. Almost anything can be made to work but you might be best off to get a specific CAN bus module.
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Last edited by 80stech; 09-11-2021 at 02:05 PM. Reason: add
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  #14  
Old 09-11-2021, 07:30 PM
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Originally Posted by 80stech View Post
I don't think the BMW CAN bus uses RS485 which could be part of your problem. RS485 is directional so the software will need to take that into account. Almost anything can be made to work but you might be best off to get a specific CAN bus module.
So do you think a module with this kind of specifications is more appropriate?
https://www.amazon.com/dp/B087PWBFV8...TQB2EDBKT15SPK
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  #15  
Old 09-11-2021, 07:39 PM
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I'm more of an Arduino guy, but yes, and that's probably even overkill but nice to have the isolation and for sure the voltage transition since I think the Pi is 3.3v. You should maybe make sure of the voltage that the X5 uses on the CANbus. Is there maybe a sketch to use the Pi as a logic analyzer ??
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  #16  
Old 09-11-2021, 07:41 PM
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Originally Posted by 80stech View Post
I'm more of an Arduino guy, but yes, and that's probably even overkill but nice to have the isolation and for sure the voltage transition since I think the Pi is 3.3v. You should maybe make sure of the voltage that the X5 uses on the CANbus. Is there maybe a sketch to use the Pi as a logic analyzer ??
Not sure about the second part, but Iíll look. I can only find it in a 2 channel variation, which I thought would be nice but I canít terminate the bus so I wouldnít be able to connect the engine and trans systems separately.
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  #17  
Old 09-11-2021, 07:50 PM
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There is no need to terminate the bus ?? Should be no reason you can't read both channels.
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  #18  
Old 09-11-2021, 09:04 PM
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The board you have is fine despite its misleading name. It has a MCP2515 CAN transceiver which I'm familiar with and have used in some BMW CAN projects of my own.

No need to worry about Pi GPIO voltage since that has nothing to do with the CAN bus voltage.

There is also little likelihood that you need to tap into the dedicated DME <-> AGS bus as well. What values are you looking to read and use in your display? I can probably help with that.
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  #19  
Old 09-11-2021, 09:07 PM
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Originally Posted by 80stech View Post
There is no need to terminate the bus ??
No, it is already terminated at each end or else it wouldn't work. If you add another device that has a termination resistor it will likely disrupt existing bus communication.
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  #20  
Old 09-11-2021, 09:08 PM
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Quote:
Originally Posted by gpeterson View Post
The board you have is fine despite its misleading name. It has a MCP2515 CAN transceiver which I'm familiar with and have used in some BMW CAN projects of my own.

No need to worry about Pi GPIO voltage since that has nothing to do with the CAN bus voltage.

There is also little likelihood that you need to tap into the dedicated DME <-> AGS bus as well. What values are you looking to read and use in your display? I can probably help with that.
So the RS458 board I talked about first will be okay? And that is good to know about the voltages. Iím looking to retrieve coolant temp (as a value), oil temp, mpg, AFR and throttle pos
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