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F28335 eZDSP CAN Communication

Ryan Hunt
Prodigy 90 points

Hello,

 

I am currently attempting to use the F28335 eZDSP to communicate to a motor controller. I have written the code, and I have working communication between two identical DSP's. However, when I add a motor controller to the CAN bus, communication does not work. I am using a Vistieon motor controller that is programmed using MotoHawk software. Baud rate is set at 250 kbaud.

I have altered the parameters on the DSP to transmit at 250 kbaud. They are as follows:

 

BRPREG = 11

TSEG2REG = 7

TSEG1REG = 15

 

I can view messages from both the motor controller and the DSP. In both, I can see the length of one bit is approximately 4 microseconds, appropriate for 250 kbaud. Mailboxes are properly set up. I can even tell that my DSP is receiving Ack bits by pausing the code in debug mode (there is a while loop that will hold to infinity if no Ack is received, this is indeed passed).

 

I am getting very frustrated, as I am out of ideas as to why communication would not be working (especially when it has worked already on two DSP's). Any help would be appreciated.

 

Thanks,

Ryan

  • 0
    Mastermind 7585 points

    That's difficult to answer.

    Your CAN - timing is correct for a data rate of 250 kbit/s. You also said that the two F28335 are able to communicate via CAN, when the motor controller is not attached.

    If you attach the motor device to your CAN you said that you can "see" messages from the motor controller device - but the communication does not work.What exactly does not work? Is the physical traffic still ok? Do you see any error frames on a CAN - Analyzer? If the physical traffic is error-free, then I guess the problems are related to the protocol, which is used in your F28335's and in the motor controller device.   Do they use the same identifier length ( 11 or 29)? Is there a conflict between identifiers in use, are some ID's used simultaneously by the nodes?