TMS320F280049C: Hrpwm: question of duty cycle adjustment in up-down mode

Green Deng said:

(1) In "both edge" mode, CMPAHR will phase shift the waveform instead of changing the duty cycle

This should not shift both edges in the same direction. It will shift the two edges towards/away from each other causing change in duty cycle only.

Hi Nima:

My customer tested it and found that the duty cycle can be modified with high accuracy in the asymmetric mode. But in symmetric mode, the two edges will move in the same direction.

What is the action qualifier settings your customer is using?

Hi Nima:

This is the action qualifier settings:

EPWM_setActionQualifierAction(ePWM[j],EPWM_AQ_OUTPUT_A,EPWM_AQ_OUTPUT_HIGH,EPWM_AQ_OUTPUT_ON_TIMEBASE_UP_CMPA);

EPWM_setActionQualifierAction(ePWM[j],EPWM_AQ_OUTPUT_A,EPWM_AQ_OUTPUT_LOW,EPWM_AQ_OUTPUT_ON_TIMEBASE_DOWN_CMPA);


HRPWM_setMEPEdgeSelect(ePWM[j], HRPWM_CHANNEL_A, HRPWM_MEP_CTRL_RISING_AND_FALLING_EDGE);
HRPWM_setMEPControlMode(ePWM[j], HRPWM_CHANNEL_A, HRPWM_MEP_DUTY_PERIOD_CTRL);
HRPWM_setCounterCompareShadowLoadEvent(ePWM[j], HRPWM_CHANNEL_A, HRPWM_LOAD_ON_CNTR_ZERO);

Hi Nima:

In addition, I would like to ask a question.

Note in the routine: The loading method of CMPA must also be ZERO and PRD.

In the manual: The loading modes of HRPWM are ZERO and PRD, but actually only the value of the shadow register is loaded at ZERO, and PRD is used for internal logic.

So will CMPA load the value of the shadow register at ZERO and PRD, or will it follow HRPWM to load only the value of the shadow register at ZERO?