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TCAN4550-Q1: How do enable internal loop back or external loopback mode

QJ Wang
Guru**** 192486 points
Part Number: TCAN4550-Q1
Other Parts Discussed in Thread: TCAN4550

Hello Expert,

TCAN4550 has two kind of loop back modes for diagnostic test. Setting LBCK bit (bit 4 of test register) will enable the loop back mode. Is there a bit to enable internal loop back and external loop back?

If loop back (internal or external) is enabled, I write data to TX fifo and transmit, I will get the same data in RX FIFO, is that correct?

  • 0
    TI__Guru 62920 points
    Hi QJ,

    We are looking into this one too. It is taking a little longer due to having people out of the office.

    Max
  • 0
    TI__Guru 73102 points
    QJ,

    You are correct in that setting LBCK bit enables the loopback mode. To set external loopback mode, you must set bit 5 in the CCCR register (0x1018) to 0, and for internal loopback mode you set bit 5 in the CCCR register to 1.

    And yes, that is correct. In loopback mode, the M_CAN treats its own transsmitted messages as received messages and stores them into an RX buffer or an RX FIFO.

    Please let me know if you have any other questions or concerns.

    Regards,
  • 0 in reply to Eric Hackett
    TI__Guru**** 192486 points
    Thanks Eric. You answered my question. I noticed that Max gave me the answer last year. Thank you all!