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CAN bit field access

kevin ***
Prodigy 230 points

HI,

I would like to access individual bits and grouped bits on my mailbox.  I can only find access to the high and low "words" at the moment.  I would ideally like to break down both high and low words into their variable values and assign them to a dedicated structure for that mailbox (does that seem prudent?)

 

Thanks

  • 0
    TI__Mastermind 20600 points

    Hi Kevin,

    The mailboxes for CAN are specific to the micro processor and the software structures and drivers you are using.  This forum is for the actual physical interface, which for CAN is seperate from the protocol layers (what the mailboxes deal with).  In order to get the support you need with respect to the specific micro processor or DSP and software it would be most efficient to post to the E2E forum specifically supporting your TI microprocessor/DSP so the appropriate software and hardware engineers can support the topic directly. 

    -- Scott

  • 0 in reply to Scott Monroe
    Prodigy 230 points

    Hi Scott, are you able to move this post? If so...I'm using a TI F28335 DSP and using CCS4. thanks 

  • 0 in reply to kevin ***
    Mastermind 7585 points

    Kevin,

    the F28x CAN - mailboxes are accesable in 3 ways:  all (32Bit), word (16bit) and byte (8bit) - just inspect the corresponding header file "DSP2833x_ECan.h" and look for union "CANMDH_REG" or "CANMDL_REG"

    Now, to adapt the existing union to accept additional access techniques is just a matter of changing that union definition. For example you can add a float member to read all 32-bit as a single folating point number. Or, you can setup any fancy combination for the 64 bits of the mailbox. It is just standard C.

     

  • 0 in reply to Frank Bormann
    Prodigy 230 points

    Many Thanks Frank - I'm slowly knocking the rust off