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TMS320F28379D: Software Continuous Forced Action on EPWM

vincent liebart
Intellectual 550 points
Part Number: TMS320F28379D

Tool/software:

Hello,

In my application, a PWM Module is running.

Sometimes I force the output of the Action Qualifier to be low using the function EPWM_setActionQualifierContSWForceAction(PWM_LE_BASE,EPWM_AQ_OUTPUT_A,EPWM_AQ_SW_OUTPUT_LOW);

The Continuous SW Force Shadow Mode is "immediate mode only"

So, when leaving this forced state using EPWM_setActionQualifierContSWForceAction(PWM_LE_BASE,EPWM_AQ_OUTPUT_A,EPWM_AQ_SW_DISABLED); I expect that I could see a part of a Period of the PWM signal before the nominal signal (red signal on the graph down below)

But the PWM signals seems to start only at the beginning of a new Period (blue signal)

Can someone explain this ?

Thank you

  • 0
    TI__Expert 4180 points

    Hello, 

    This is the note from device TRM, page 2067: "Continuous Software Force on Output A (CSFA) in immediate mode takes effect on the next TBCLK edge.", and there is a note that says: "If the CSFA is not used in shadow mode, the RLDCSF bit must be configured to disable shadow mode."

  • 0 in reply to Stevan Duraskovic
    Intellectual 550 points

    Hello, I already took this into account. My RLDCSF bit is well configured, and I expected that the continuous action would take effect on the next TBCLK edge. But it seems it takes effect on the next PWM period. 

    The TRM mentions continuous pulses for the Continuous Software Forced Action. But I did not understand what are these pulses. Are they linked to the Sync pulses ? These are configured to be generated at each period actually.

  • +1 in reply to vincent liebart
    TI__Expert 4180 points

    Hello,

    Disable action for Continuous SW force is not done using logic gates which would make action to happen immediately when called. But it's tied to Action Qualifier action which happens at the event, in this case event counter zero event. That's why the waveform is like shown in blue.

  • 0 in reply to Stevan Duraskovic
    Intellectual 550 points

    Thank you Stevan, it's very clear for me.