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TMS320F28377D: T1 event for EPWMxA output

Jordan Zhou
Genius 10070 points
Part Number: TMS320F28377D
Other Parts Discussed in Thread: SYSCONFIG, C2000WARE

Hi,

Some doubts about EPWM1A output from T1 event.

In my application, PWM1A output is wrong. GPIO29 is used as TZ. TZ is used as T1 event. 

On count up, T1 event will set output low; on count down, set high.

The TZ signal input source comes from another PWM output, the same frequency, period 1500. 

I found that, there's very few action output on PWM1A. For example, 100 PWM cycles, only one PWM1A output appears. And the frequency is not fixed. 

What could be the issue?

Here's the init code for EPWM1:

 EPWM_setEmulationMode(myEPWM1_BASE, EPWM_EMULATION_FREE_RUN);
EPWM_setClockPrescaler(myEPWM1_BASE, EPWM_CLOCK_DIVIDER_1, EPWM_HSCLOCK_DIVIDER_1);
EPWM_setTimeBasePeriod(myEPWM1_BASE, 1500);
EPWM_setTimeBaseCounter(myEPWM1_BASE, 0);
EPWM_setTimeBaseCounterMode(myEPWM1_BASE, EPWM_COUNTER_MODE_UP_DOWN);
EPWM_setCountModeAfterSync(myEPWM1_BASE, EPWM_COUNT_MODE_UP_AFTER_SYNC);
EPWM_disablePhaseShiftLoad(myEPWM1_BASE);
EPWM_setPhaseShift(myEPWM1_BASE, 0);
EPWM_setCounterCompareValue(myEPWM1_BASE, EPWM_COUNTER_COMPARE_A, 250);
EPWM_setCounterCompareShadowLoadMode(myEPWM1_BASE, EPWM_COUNTER_COMPARE_A, EPWM_COMP_LOAD_ON_CNTR_ZERO);
EPWM_setCounterCompareValue(myEPWM1_BASE, EPWM_COUNTER_COMPARE_B, 0);
EPWM_setCounterCompareShadowLoadMode(myEPWM1_BASE, EPWM_COUNTER_COMPARE_B, EPWM_COMP_LOAD_ON_CNTR_ZERO);
EPWM_setActionQualifierT1TriggerSource(myEPWM1_BASE, EPWM_AQ_TRIGGER_EVENT_TRIG_TZ_1);
EPWM_setActionQualifierT2TriggerSource(myEPWM1_BASE, EPWM_AQ_TRIGGER_EVENT_TRIG_TZ_1);
EPWM_setActionQualifierAction(myEPWM1_BASE, EPWM_AQ_OUTPUT_A, EPWM_AQ_OUTPUT_NO_CHANGE, EPWM_AQ_OUTPUT_ON_TIMEBASE_ZERO);
EPWM_setActionQualifierAction(myEPWM1_BASE, EPWM_AQ_OUTPUT_A, EPWM_AQ_OUTPUT_NO_CHANGE, EPWM_AQ_OUTPUT_ON_TIMEBASE_PERIOD);
EPWM_setActionQualifierAction(myEPWM1_BASE, EPWM_AQ_OUTPUT_A, EPWM_AQ_OUTPUT_NO_CHANGE, EPWM_AQ_OUTPUT_ON_TIMEBASE_UP_CMPA);
EPWM_setActionQualifierAction(myEPWM1_BASE, EPWM_AQ_OUTPUT_A, EPWM_AQ_OUTPUT_NO_CHANGE, EPWM_AQ_OUTPUT_ON_TIMEBASE_DOWN_CMPA);
EPWM_setActionQualifierAction(myEPWM1_BASE, EPWM_AQ_OUTPUT_A, EPWM_AQ_OUTPUT_NO_CHANGE, EPWM_AQ_OUTPUT_ON_TIMEBASE_UP_CMPB);
EPWM_setActionQualifierAction(myEPWM1_BASE, EPWM_AQ_OUTPUT_A, EPWM_AQ_OUTPUT_NO_CHANGE, EPWM_AQ_OUTPUT_ON_TIMEBASE_DOWN_CMPB);
EPWM_setActionQualifierAction(myEPWM1_BASE, EPWM_AQ_OUTPUT_A, EPWM_AQ_OUTPUT_LOW, EPWM_AQ_OUTPUT_ON_T1_COUNT_UP);
EPWM_setActionQualifierAction(myEPWM1_BASE, EPWM_AQ_OUTPUT_A, EPWM_AQ_OUTPUT_HIGH, EPWM_AQ_OUTPUT_ON_T1_COUNT_DOWN);
EPWM_setActionQualifierAction(myEPWM1_BASE, EPWM_AQ_OUTPUT_B, EPWM_AQ_OUTPUT_NO_CHANGE, EPWM_AQ_OUTPUT_ON_TIMEBASE_ZERO);
EPWM_setActionQualifierAction(myEPWM1_BASE, EPWM_AQ_OUTPUT_B, EPWM_AQ_OUTPUT_NO_CHANGE, EPWM_AQ_OUTPUT_ON_TIMEBASE_PERIOD);
EPWM_setActionQualifierAction(myEPWM1_BASE, EPWM_AQ_OUTPUT_B, EPWM_AQ_OUTPUT_NO_CHANGE, EPWM_AQ_OUTPUT_ON_TIMEBASE_UP_CMPA);
EPWM_setActionQualifierAction(myEPWM1_BASE, EPWM_AQ_OUTPUT_B, EPWM_AQ_OUTPUT_NO_CHANGE, EPWM_AQ_OUTPUT_ON_TIMEBASE_DOWN_CMPA);
EPWM_setActionQualifierAction(myEPWM1_BASE, EPWM_AQ_OUTPUT_B, EPWM_AQ_OUTPUT_HIGH, EPWM_AQ_OUTPUT_ON_TIMEBASE_UP_CMPB);
EPWM_setActionQualifierAction(myEPWM1_BASE, EPWM_AQ_OUTPUT_B, EPWM_AQ_OUTPUT_LOW, EPWM_AQ_OUTPUT_ON_TIMEBASE_DOWN_CMPB);
EPWM_setTripZoneAction(myEPWM1_BASE, EPWM_TZ_ACTION_EVENT_TZA, EPWM_TZ_ACTION_DISABLE);
EPWM_setTripZoneAction(myEPWM1_BASE, EPWM_TZ_ACTION_EVENT_TZB, EPWM_TZ_ACTION_DISABLE);
EPWM_selectDigitalCompareTripInput(myEPWM1_BASE, EPWM_DC_TRIP_TRIPIN2, EPWM_DC_TYPE_DCAL);

Thanks a lot.

Br, Jordan

  • 0
    TI__Mastermind 25916 points

    Hi Jordan,

    Could you provide an screenshot of your scope readings for TZ1, and the PWM output at A? TZ1 is active low input signal.

    Also keep in mind that a minimum of 3*TBCLK low pulse width on the inputs is sufficient to cause a trigger.

  • 0 in reply to Ryan Ma
    TI__Genius 10070 points

    Will you provide me a domo code, please?

    I did a demo, PWM output to TZ, TZ was used as T1. The output of PWM is not what we want, there is PWM output pulse, but the output is not the same as TZ input,

    Br, Jordan

  • 0 in reply to Jordan Zhou
    TI__Mastermind 25916 points

    Hi Jordan,

    Most of your setup seems correct, however how are you tripping your outputs? are you doing a one shot or cycle by cycle clearing? Are you configuring this setup through SysConfig?

    It seems you might be missing a configuration similar to our example within our C2000Ware SDK (example 1), where we configure epwm1 to be one shot tripped, and epwm2 to be cycle by cycle tripped.

    In order to trigger the trip, you will need the input to go low. Then depending on your setup make sure you're clearing the one shot or cycle by cycle flags in order to repeat the trip behaviors.

    Best,

    Ryan Ma