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TMS320F28075: Time stamps for Controller Area Network (CAN)

Demis Biscaro
Expert 1145 points

Part Number: TMS320F28075

Hello,

I need to use CAN peripheral on TMS320F28075 microcontroller. I've read CAN chapter of Technical Reference Manual (spruh9mb, revised September 2015) but I didn't find any reference to Time stamps.

I used Time Stamps of eCAN module in TMS32F28335 and I presumed that TMS320F28075 implemented them too, but I didn't find them.

To be sure, does CAN module in TMS32F28335 implement Time Stamps? Or not?

Thank you.

Demis Biscaro

  • 0
    TI__Guru* 95315 points

    Demis,

      I think you wanted to ask "does CAN module in TMS320F28075 implement Time Stamps?" The answer is "No". Time-stamping is not implemented on the DCAN module of 28075.

  • 0 in reply to Hareesh Janakiraman
    TI__Guru* 95315 points

    Demis,

                I was searching through my archive and came upon this idea from a colleague of mine. Thought it might be of use to you to implement time-stamping:

     

    Define a 32 x 32-bit array (for 32 mailboxes)

    Configure an available timer for up-counting mode.

    In message transmission/reception interrupt, save counter of timer to corresponding array element

    By reading the content of the array, it is similar to MOTS of each mailbox.

     

    Note that this method only emulates the time-stamp feature of eCAN, not the time-out feature.

     

    In the CAN module of28004 device, CAN interrupt 0 (INT0) is connected to the input of eCAP module. An interrupt generated upon successful transmission/reception could be used to capture the value of the eCAP counter, thereby enabling time-stamping. The INT0 line of each CAN module is connected to the eCAP input as shown in the table below:

     

    Module Interrupt Line           eCAP input

               

                CANB_INT0                             21

                CANA_INT0                             20

     

  • 0 in reply to Hareesh Janakiraman
    Expert 1145 points
    Thank you for your answer, Hareesh.
    You are right: I wanted to ask about Time Stamps in TMS320F28075.

    Thank you for your hints, too.
    The workaround with 32x32 bit array and interrupt routine is clear to me. I thought of it before writing my question, but I don't like it much because of delay in servicing interrupt routine (or interrupt suspending!), software overhead, ecc.

    The second hint with eCAP seems more interesting. However I've read eCAP chapter in Technical Manual of TMS320F28075 but I don't understand how to connect CAN interrupt 0 (INT0) to eCAP module. It seems that only a physical input (i.e. a GPIO) can trigger a capture on eCAP module. So I could connect CAN RX or CAN TX line to eCAP module but not INT0 (or INT1) interrupt line. Is it correct?
  • 0 in reply to Demis Biscaro
    TI__Guru* 95315 points

    Demis,

    I was referring to 280049 device (not released to production yet, but datasheet is available on the web), not the 28075. This method is not applicable to 28075.