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AM2434: How can PWM be shut down by interrupt ?

Hideaki Matsumoto
Genius 9090 points
Part Number: AM2434

Tool/software:

Hi,

My customer wants to shut down each PWM separately by interrupt like a emergency stop. How can they do that ?

Q1)  Is it possible to use the following signal detection for PWM shutdown ?

  1.  Input the signal into PWM Trip (TZ_IN)

  2.  Input the signal into GPIO on Main Domain

  3.  Input the signal into GPI on PRU-ICSSG

  4.  Any Other way ?

Q2) Could you tell them what the latency is by the above each method ?

Q3) What is the trigger type available ? Edge, Level or other ?

It would be appreciated if we can receive your answers as soon as possible.

If it's difficult, could you please give an answer to at least Q1) at first.

Thanks and regards,

Hideaki

  • 0
    TI__Mastermind 39100 points

    Matsumoto-san, I will reach out to one of our experts for confirmation, but my understanding is that we should use TZ for this type of scenarios.

    From academy (EPWM C2000 - as a reference) Enhanced Pulse Width Modulation (EPWM)

    "The trip-zone submodule utilizes a fast clock-independent logic mechanism to quickly handle fault conditions by forcing the EPWMxA and EPWMxB outputs to a safe state, such as high, low, or high-impedance, thus avoiding any interrupt latency that may not protect the hardware when responding to over current conditions or short circuits through ISR software."

    Additional information in TRM's  "12.4.3.1.1 EPWM Features" AM64x/AM243x Technical Reference Manual (Rev. H) (ti.com)

    Also, there is a TZ example in our MCU+SDK in case your customer wants to test it. They can directly check the type of input/outputs available for TZ and use it to get latency numbers directly from there:

    AM243x MCU+ SDK: EPWM trip zone (ti.com)

    Please let me know if this clarifies your questions or if you need additional information

    thank you,

    Paula

  • 0 in reply to Paula Carrillo
    TI__Genius 9090 points

    Hi Paula,

    Thank you for your reply and sorry for my late response.

    Is it possible to use GPIO in Main domain or PRU-ICSSG ?

    If it’s possible, could you tell them what the latency is ?

    We know it takes much latency, but there is no available pin of PWM Trip (TZ_IN) due to PinMux.

    Thanks and regards,
    Hideaki

  • 0 in reply to Hideaki Matsumoto
    TI__Mastermind 39100 points

    Matsumoto-san, I am out of office today, but tomorrow I will check if we have any GPIO latency data available to share

    thank you,

    Paula 

  • 0 in reply to Hideaki Matsumoto
    TI__Mastermind 46276 points
    Hideaki Matsumoto said:

    We know it takes much latency, but there is no available pin of PWM Trip (TZ_IN) due to PinMux.

    Hello Hideaki,

    The use of a trip zone is if any short circuit or over voltage or over current happens, then we need to stop the PWM very quickly.

    This is already supported by the PWM and there is already an example on this topic.

    Please look at the Application  path  .

    C:\ti\mcu_plus_sdk_am243x_09_02_00_50\examples\drivers\epwm\epwm_trip_zone

    Currently, the TZ pin is not configurable on the CFG system, but users can manually write the PAD cfg registers to enable the TZ function.

    Please look at the image below .

    With this example you can just confirm how much latency it is taking to stop the PWM once the TZ signal is triggered.

    ​We don't have data on this latency . If this method is causing more latency, then we can check other methods, but I am assuming that this feature is supported by the PWM module itself. So, the latency will be less as  compared to other methods.

    Regards,

    Anil.