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Usage of WDT in power conversion application.

Asad Hameed
Intellectual 725 points

Part Number: TMS320F28377S
Other Parts Discussed in Thread: C2000WARE

We are designing a power conversion application for hybrid solar system. We have completed the alpha phase and now planning the Beta stage. So far we have not used WDT in our application and it appears that the software design is robust enough and working without any software freezing. We understand that the software design for real time controls must be properly scheduled and checked with time profiling to ensure all processes get required CPU bandwidth. We are not sure if WDT is actually a good or necessary feature to be enabled for real time controls applications such as power conversion and should we consider using it for better system reliability. Related to this subject: does a WDT reset places all the PWMs into safe trip state?.

Please guide in this regard.

  • 0
    TI__Guru** 116081 points

    Hi Asad,

    WDT is device recovery mechanism for safety application so user need to see if this is really needed for them. If you enable WD then you need to have periodic function call to service this WD so that it does not overflow. 

    Asad Hameed said:
    Related to this subject: does a WDT reset places all the PWMs into safe trip state?.

    Yes, WDT reset reset the PWMs as well as IOs so it goes into safe state.

    Regards,

    Vivek Singh

  • 0 in reply to Vivek Singh
    Intellectual 725 points

    Hi Vivek Singh,

         Thank you very much for a precise reply. Actually I have noticed that the watch dog timer is usually disabled in the examples available in C2000Ware.  The device initialization functions start with the following lines of code:

    void Device_init(void)
    {
    //
    // Disable the watchdog
    //
    SysCtl_disableWatchdog();

    We have also built up our application using this default approach. 

    From your response we understand that:  it is as such not recommended to necessarily use WDT but it is a matter of choice depending on the application. Please correct me if I am wrong.

  • 0 in reply to Asad Hameed
    TI__Guru** 116081 points

    Hi Asad,

    Asad Hameed said:
    it is as such not recommended to necessarily use WDT but it is a matter of choice depending on the application. Please correct me if I am wrong.

    As mentioned earlier, usage of WDT depends on application need and user need to decide if they want to use it or not. If application is safety critical then user need to refer to our safety manual and follow the recommendations provided in it.

    Regards,

    Vivek Singh