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TCAN4550-Q1: Loopback mode on TCAN4550

QJ Wang
Guru**** 192956 points
Part Number: TCAN4550-Q1
Other Parts Discussed in Thread: TCAN4550

Hello,

I am working on a project with Hercules MCU + TCAN4550. In my code, I want to add safety related diagnostic test for TCAN45x. How can I used the external and internal loopback which is stated in datasheet? I could not find the register for selecting internal and external loopback mode. Thanks

  • 0
    TI__Guru 62920 points
    Hi QJ,

    You can enable MCAN loopback by setting bit 4 (LBCK) of register 0x1010. Please let me know if you have any issues with it.

    Regards,
    Max
  • 0 in reply to Miguel Robertson
    TI__Guru**** 192956 points
    Thanks Max.

    This bit is to enable the loopback. Which bits are used to select external loop back mode and internal loopback mode?
  • 0 in reply to QJ Wang
    TI__Guru 62920 points
    Hi QJ,

    Sorry, I was out on vacation for the last week and a half and missed your message. Setting LPBK makes it so that the RX input to the CAN controller comes from its TX output rather than the bus, which corresponds to the "external" loop back configuration. To disable the external TX output from the controller (i.e., to achieve internal-only loop back), you can set the MON bit (bit 5) of register 0x1018. This forces a "1" at the TX line going to the transceiver, keeping it in a recessive state.

    Regards,
    Max