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TCAN1042-Q1: Question on implementation

Mitchell
Expert 4915 points
Part Number: TCAN1042-Q1
Other Parts Discussed in Thread: AWR1843

Hi Team,

My customer would like to hear your feedback on whether or not a CAN transceiver is required for their application? In their system, they have a CAN-FD controller that outputs data through a flex cable and over to a downstream device (AWR1843). The total distance between these two devices is about 2 inches.

Thanks,
Mitchell

  • 0
    TI__Intellectual 2090 points
    Hi Mitchell,

    Could you describe the data processing capability of the AWR1843? Does this device have a protocol controller to process CAN FD data on its end? If you only have the ability to output CAN FD protocol data from a controller/transceiver combination, then I want to make sure that the AWR1843 device will be able to decode the CAN FD data on its input pins. How is the AWR1843 meant to receive input data?

    Best Regards,
    Max Megee
    TI TRX Applications
  • 0 in reply to Max Megee
    TI__Expert 4915 points
    Hi Max,

    Yes, AWR1843 has full support for CAN-FD on it's end. Please refer to page 38 or section 5.10.7 of the AWR1843 datasheet.

    Thanks,
    Mitchell
  • 0 in reply to Mitchell
    TI__Guru 62920 points
    Hi Mitchell,

    Logic-level signals should be able to make it across a two-inch cable, so as long as there are no grounding differences that would necessitate differential-mode signaling then there shouldn't be an issue from a signal integrity standpoint.

    From a protocol standpoint, you need to make sure that each node sees the data that it is transmitting looped back to the receiver and allow for cases where both nodes transmit dominant simultaneously (for example, during the arbitration portion of a CAN frame). So, you couldn't just simply connect TXD of one node to RXD of the other and vice-versa.

    However, you could solve this by converting each TXD output to open-drain by using diodes with cathodes connected to TXD and anodes connected to a common bus. This bus could have a pull-up resistance on it and could connect to the RXD line of both nodes. This way, the logic-level signals will behave similarly to the differential signals that a CAN transceiver produces. That is, any node driving the bus low/dominant will result in a low/dominant bus to be observed by all nodes; when no nodes drive the bus low/dominant it will be observed to be high/recessive by all nodes.

    Regards,
    Max