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TCAN1146-Q1: WAKE via WUP only

Antoine Chapuis1
Expert 5950 points
Part Number: TCAN1146-Q1

Hello team,

My customer is looking to wake up the TCAN1146 via WUP only, meaning they want to disable completely any 'wake via CAN' or WUF functionality.

To do so, they have configured the transceiver in the following way:

Register ->          Value

0x1C      ->           0x04      /*SWE timer disabled*/

0x15      ->           0x00      /*Disable Wdg_1*/ /*Should already be OFF */

0x56      ->           0x00      /*Disable all interrupts on INT_1*/

0x57      ->           0x00      /*Disable all interrupts on INT_2*/

0x58      ->           0x00      /*Disable all interrupts on INT_3*/

0x59      ->           0x00      /*Disable all interrupts on INT_CANBUS*/           

0x51      ->           0xFF       /*Clear all interrupts on INT_1*/

0x52      ->           0xFF       /*Clear all interrupts on INT_2*/

0x53      ->           0xE1      /*Clear all interrupts on INT_3*/

0x54      ->           0x7F      /*Clear all interrupts on INT_CANBUS*/

0x10      ->           0x47      /*Mode register to normal*/

However after this, putting the tcan in sleep mode is immediately followed by a wake-up, and the interrupt register mentions a 'CAN bus wake up'. This happens only when the trx is connection to a CAN bus. If the CAN connections are open, nothing happens.

I have asked about WAKE pin connection and configuration, but in the meantime I submit this question to you: How should they do to disable wake up via CAN?

Best regards, Antoine

  • +1
    TI__Guru 53575 points

    Hi Antoine,

    It is not possible to explicitly disable wake via CAN. If partial networking is disabled, the wake up pulse (WUP) recognition will be used. However, we can use the partial networking feature of the device to ignore any CAN frame that does not fit the desired requirements. In other words, a wake up frame (WUF) can be defined that is never expected to exist on this CAN network. See this app note for a configuration guide for selective wake. With this setup, the only expected wake event will be a local wake up (LWU) via the WAKE pin. 

    Let me know if you have any more questions.

    Regards,
    Eric Schott

  • 0 in reply to Eric Schott1
    TI__Expert 5950 points

    Hi Eric,

    Your explanation is clear. The customer has just shared that in fact they do not use the WAKE pin, so I expect they use the SPI

    I will share your answer with the appnote and come back to you in case it does not solve the case.

    Best regards, Antoine