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LP87745: Writing into watchdog disable bit

Nibin Augustine
Prodigy 90 points
Part Number: LP87745

Tool/software:

Hello,

I am working on external watchdog implementation. 

What will happen if I write value 0x00 to WD_ENABLE_REG when it's already '0' (I mean current value of WD_ENABLE_REG is zero already and we write the same value after some time )

Is there any chance for malfunctioning if we re-write the value again?

Regards

Nibin Augustine

  • 0
    TI__Genius 16350 points

    Hi Nibin,

    No nothing should happen. It would just keep it in the same state if your write is successful. 

    Regards,

    Ishtiaque

  • 0 in reply to Ishtiaque Panhwar
    Prodigy 90 points

    Thanks for your response

    I have one more question

    Consider I set reset threshold + fail threshold = 5

    current reset threshold + fail threshold value = 5

    Now i set WD_RETURN_LONGWIN = True

     and send  four wrong answer bytes to PMIC. So after this step watchdog will trigger a reset or it will return to long window?

    Regards

    Nibin Augustine

  • 0 in reply to Nibin Augustine
    TI__Genius 16350 points

    Hi Nibin,

    When wrong answer is provided the WD fail counter (WD_FAIL_CNT) increase. so if the WD_FAIL_CNT increase more than 5 (of WD reset threshold+WD fail threshold) and if the WD_RST_EN=1 bit is set then device would have warm reset, error flag set (WD_RST) and activates the interrupt  pin and CAN_DIS output. 

    After the warm_reset  time extension has elapsed then it returns back to the long window and expects the correct answer sequence with long window time period. 

    You can refer to the page 42 for watchdog section in the datasheet. Also refer the WD flow diagram in the DS. 

    Regards,

    Ishtiaque