RM48L952: Watchdog monitoring program sequence

Part Number: RM48L952

Hi TI,

We are currently working on the safety application which should be compliant to IEC-61508 standards. We are using the Hercules RM48x microcontroller in our design. 

For safety, is there a way the watchdog can monitor the program sequence? Is there any reference application code or design available?

Please provide your suggestions, if any.

Regards,

Monish P

  • Hi Monitor,

    The watchdog timer is based on a counter that counts down from some initial value to zero. The software specifies the counter’s initial value and periodically restarts it by servicing the watchdog within the time window. If the counter ever reaches zero before the watchdog is serviced, the software is presumed to be malfunctioning, and either the processor’s reset signal or a NMI interrupt signal is asserted.

    A watchdog timer can get a system out of a lot of dangerous situations. However, you need to know what kinds of things could go wrong with your software, and ensure that the watchdog timer will detect them, if any occur. The maximum watchdog expiration time is (4095 + 1) × 2^13/RTICLK. It will be a challenge if some part of your software takes a long time to complete.

    I am not sure how to monitor the program sequence using the watchdog. 

  • Thanks, Wang,

    Our requirement is by using the external watchdog IC, we want to monitor the program sequence. Also, the other requirement is watchdog should reset the MCU when any kind of ESM error occurs.

    So, we want to choose the watchdog IC which shall satisfy the above cases. 

    Regards,

    Monish P 

  • Hi Wang,

    Please provide your suggestions, if any.

  • Hi Monish,

    TPS65381 can be used to power supply TMS570 MCU. It has a watchdog accepting command from MCU through SPI interface. The TPS65382 can issue a power-on reset if a severe error occurs (ESM group 3 error).

    https://www.ti.com/lit/an/spna176a/spna176a.pdf?ts=1632512457947&ref_url=https%253A%252F%252Fwww.google.com%252F