LAUNCHXL-F280025C: Universal motor lab: Using a higher system clock

Jagbir

Part Number: LAUNCHXL-F280025C
Other Parts Discussed in Thread: C2000WARE

Hi ,

The lab example uses a PWM time period number macro, which I believe is for a 100Mhz system clock using the LAUNCHXL-F280025C.

#define USER_M1_PWM_TBPRD_NUM (uint16_t)(USER_SYSTEM_FREQ_MHz * 1000.0f / USER_M1_PWM_FREQ_kHz / 2.0f)

This macro is being used by HAL_setupPWMs() for setting the pwmPeriodCycles.

uint16_t pwmPeriodCycles = (uint16_t)(USER_M1_PWM_TBPRD_NUM);

I plan to run at 50KHz PWM with a system clock of 200MHz on my custom board. What is the recommended value for this macro for a 200MHz system clock? I have tried a few combinations. For example, if I divide by 4 in the macro, to compensate for doubling the sys clock, then my PWM out is 50 KHz, but the example did not run. The TBPRD was 1000, and CMPA was 500.

If I try to set TBPRD as 2500 and CMPA as 1250 (divided by 1.6) then my output PWM is 20KHz, against the target PWM of 50Khz.

void HAL_setupPWMs(HAL_MTR_Handle handle)
{
    HAL_MTR_Obj    *obj = (HAL_MTR_Obj *)handle;
    uint16_t  cnt;

    uint16_t       pwmPeriodCycles = (uint16_t)(USER_M1_PWM_TBPRD_NUM);
    uint16_t       numPWMTicksPerISRTick = USER_M1_NUM_PWM_TICKS_PER_ISR_TICK;

    // disable the ePWM module time base clock sync signal
    // to synchronize all of the PWMs
    SysCtl_disablePeripheral(SYSCTL_PERIPH_CLK_TBCLKSYNC);

    // turns off the outputs of the EPWM peripherals which will put the power
    // switches into a high impedance state.
    EPWM_forceTripZoneEvent(obj->pwmHandle[0], EPWM_TZ_FORCE_EVENT_OST);
    EPWM_forceTripZoneEvent(obj->pwmHandle[1], EPWM_TZ_FORCE_EVENT_OST);
    EPWM_forceTripZoneEvent(obj->pwmHandle[2], EPWM_TZ_FORCE_EVENT_OST);

#if defined(BSXL8323RS_REVA) || defined(BSXL8323RH_REVB) || \
    defined(BSXL8353RS_REVA) || defined(BSXL8316RT_REVA) || \
    defined(BSXL3PHGAN_REVA) || defined(HVMTRPFC_REV1P1) || \
    defined(DRV8329AEVM_REVA)

    for(cnt=0; cnt<3; cnt++)
    {
        // setup the Time-Base Control Register (TBCTL)
        EPWM_setTimeBaseCounterMode(obj->pwmHandle[cnt],
                                    EPWM_COUNTER_MODE_UP_DOWN);

        EPWM_disablePhaseShiftLoad(obj->pwmHandle[cnt]);

        EPWM_setPeriodLoadMode(obj->pwmHandle[cnt], EPWM_PERIOD_DIRECT_LOAD);
/* Commented JS
        EPWM_enableSyncOutPulseSource(obj->pwmHandle[cnt],
                                      EPWM_SYNC_OUT_PULSE_ON_SOFTWARE);
*/
        EPWM_setClockPrescaler(obj->pwmHandle[cnt], EPWM_CLOCK_DIVIDER_2,
                                 EPWM_HSCLOCK_DIVIDER_2);

        EPWM_setCountModeAfterSync(obj->pwmHandle[cnt],
                                   EPWM_COUNT_MODE_UP_AFTER_SYNC);

        EPWM_setEmulationMode(obj->pwmHandle[cnt], EPWM_EMULATION_FREE_RUN);

        // setup the Timer-Based Phase Register (TBPHS)
        EPWM_setPhaseShift(obj->pwmHandle[cnt], 0);

        // setup the Time-Base Counter Register (TBCTR)
        EPWM_setTimeBaseCounter(obj->pwmHandle[cnt], 0);

        // setup the Time-Base Period Register (TBPRD)
        // set to zero initially
        EPWM_setTimeBasePeriod(obj->pwmHandle[cnt], 0);

        // setup the Counter-Compare Control Register (CMPCTL)
        EPWM_setCounterCompareShadowLoadMode(obj->pwmHandle[cnt],
                                             EPWM_COUNTER_COMPARE_A,
                                             EPWM_COMP_LOAD_ON_CNTR_ZERO);

        EPWM_setCounterCompareShadowLoadMode(obj->pwmHandle[cnt],
                                             EPWM_COUNTER_COMPARE_B,
                                             EPWM_COMP_LOAD_ON_CNTR_ZERO);

        EPWM_setCounterCompareShadowLoadMode(obj->pwmHandle[cnt],
                                             EPWM_COUNTER_COMPARE_C,
                                             EPWM_COMP_LOAD_ON_CNTR_ZERO);

        EPWM_setCounterCompareShadowLoadMode(obj->pwmHandle[cnt],
                                             EPWM_COUNTER_COMPARE_D,
                                             EPWM_COMP_LOAD_ON_CNTR_ZERO);

#if defined(MOTOR1_ISBLDC)
        // setup the Action-Qualifier Output A Register (AQCTLA)
        EPWM_setActionQualifierAction(obj->pwmHandle[cnt],
                                      EPWM_AQ_OUTPUT_A,
                                      EPWM_AQ_OUTPUT_HIGH,
                                      EPWM_AQ_OUTPUT_ON_TIMEBASE_UP_CMPA);

        EPWM_setActionQualifierAction(obj->pwmHandle[cnt],
                                      EPWM_AQ_OUTPUT_A,
                                      EPWM_AQ_OUTPUT_LOW,
                                      EPWM_AQ_OUTPUT_ON_TIMEBASE_DOWN_CMPA);

        // setup the Action-qualifier Continuous Software Force Register (AQCSFRC)
        EPWM_setActionQualifierContSWForceAction(obj->pwmHandle[cnt],
                                                 EPWM_AQ_OUTPUT_B,
                                                 EPWM_AQ_SW_OUTPUT_LOW);

        // setup the Dead-Band Generator Control Register (DBCTL)
        EPWM_setDeadBandDelayMode(obj->pwmHandle[cnt], EPWM_DB_RED, false);
        EPWM_setDeadBandDelayMode(obj->pwmHandle[cnt], EPWM_DB_FED, false);

#else   //!MOTOR1_ISBLDC


#if defined(MOTOR1_DCLINKSS)
        // setup the Action-Qualifier Output A Register (AQCTLA)
        EPWM_setActionQualifierAction(obj->pwmHandle[cnt],
                                      EPWM_AQ_OUTPUT_A,
                                      EPWM_AQ_OUTPUT_HIGH,
                                      EPWM_AQ_OUTPUT_ON_TIMEBASE_UP_CMPA);

        EPWM_setActionQualifierAction(obj->pwmHandle[cnt],
                                      EPWM_AQ_OUTPUT_A,
                                      EPWM_AQ_OUTPUT_LOW,
                                      EPWM_AQ_OUTPUT_ON_TIMEBASE_DOWN_CMPB);

        EPWM_setActionQualifierAction(obj->pwmHandle[cnt],
                                      EPWM_AQ_OUTPUT_A,
                                      EPWM_AQ_OUTPUT_LOW,
                                      EPWM_AQ_OUTPUT_ON_TIMEBASE_ZERO);

        EPWM_setActionQualifierAction(obj->pwmHandle[cnt],
                                      EPWM_AQ_OUTPUT_A,
                                      EPWM_AQ_OUTPUT_HIGH,
                                      EPWM_AQ_OUTPUT_ON_TIMEBASE_PERIOD);
#else  // !(MOTOR1_DCLINKSS)
        // setup the Action-Qualifier Output A Register (AQCTLA)
        EPWM_setActionQualifierAction(obj->pwmHandle[cnt],
                                      EPWM_AQ_OUTPUT_A,
                                      EPWM_AQ_OUTPUT_HIGH,
                                      EPWM_AQ_OUTPUT_ON_TIMEBASE_UP_CMPA);

        EPWM_setActionQualifierAction(obj->pwmHandle[cnt],
                                      EPWM_AQ_OUTPUT_A,
                                      EPWM_AQ_OUTPUT_HIGH,
                                      EPWM_AQ_OUTPUT_ON_TIMEBASE_PERIOD);

        EPWM_setActionQualifierAction(obj->pwmHandle[cnt],
                                      EPWM_AQ_OUTPUT_A,
                                      EPWM_AQ_OUTPUT_LOW,
                                      EPWM_AQ_OUTPUT_ON_TIMEBASE_DOWN_CMPA);

        EPWM_setActionQualifierAction(obj->pwmHandle[cnt],
                                      EPWM_AQ_OUTPUT_A,
                                      EPWM_AQ_OUTPUT_LOW,
                                      EPWM_AQ_OUTPUT_ON_TIMEBASE_ZERO);

#endif  // !(MOTOR1_DCLINKSS)

        // setup the Dead-Band Generator Control Register (DBCTL)
        EPWM_setDeadBandDelayMode(obj->pwmHandle[cnt], EPWM_DB_RED, true);
        EPWM_setDeadBandDelayMode(obj->pwmHandle[cnt], EPWM_DB_FED, true);

        // select EPWMA as the input to the dead band generator
        EPWM_setRisingEdgeDeadBandDelayInput(obj->pwmHandle[cnt],
                                             EPWM_DB_INPUT_EPWMA);

        // configure the right polarity for active high complementary config.
        EPWM_setDeadBandDelayPolarity(obj->pwmHandle[cnt],
                                      EPWM_DB_RED,
                                      EPWM_DB_POLARITY_ACTIVE_HIGH);
        EPWM_setDeadBandDelayPolarity(obj->pwmHandle[cnt],
                                      EPWM_DB_FED,
                                      EPWM_DB_POLARITY_ACTIVE_LOW);

        // setup the Dead-Band Rising Edge Delay Register (DBRED)
        EPWM_setRisingEdgeDelayCount(obj->pwmHandle[cnt], MTR1_PWM_DBRED_CNT);

        // setup the Dead-Band Falling Edge Delay Register (DBFED)
        EPWM_setFallingEdgeDelayCount(obj->pwmHandle[cnt], MTR1_PWM_DBFED_CNT);

#endif  //!MOTOR1_ISBLDC

        // setup the PWM-Chopper Control Register (PCCTL)
        EPWM_disableChopper(obj->pwmHandle[cnt]);

        // setup the Trip Zone Select Register (TZSEL)
        EPWM_disableTripZoneSignals(obj->pwmHandle[cnt], HAL_TZSEL_SIGNALS_ALL);
    }

    // BSXL8323RS_REVA || BSXL8323RH_REVB || BSXL8353RS_REVA || \
    // BSXL8316RT_REVA || BSXL3PHGAN_REVA || HVMTRPFC_REV1P1 || \
    // DRV8329AEVM_REVA
#else
#error The PWM is not configured for motor_1 control
#endif  // boards

#if defined(MOTOR1_ISBLDC)
    // setup the Event Trigger Selection Register (ETSEL)
    EPWM_setInterruptSource(obj->pwmHandle[0], EPWM_INT_TBCTR_ZERO);

    EPWM_disableInterrupt(obj->pwmHandle[0]);

    EPWM_setADCTriggerSource(obj->pwmHandle[0],
                             EPWM_SOC_A, EPWM_SOC_TBCTR_ZERO);

    EPWM_enableADCTrigger(obj->pwmHandle[0], EPWM_SOC_A);

    EPWM_setADCTriggerSource(obj->pwmHandle[0],
                              EPWM_SOC_B, EPWM_SOC_TBCTR_U_CMPB);

    EPWM_enableADCTrigger(obj->pwmHandle[0], EPWM_SOC_B);
#elif defined(MOTOR1_DCLINKSS)
    // setup the Event Trigger Selection Register (ETSEL)
    EPWM_setInterruptSource(obj->pwmHandle[0], EPWM_INT_TBCTR_ZERO);

    EPWM_enableInterrupt(obj->pwmHandle[0]);

    EPWM_setADCTriggerSource(obj->pwmHandle[0],
                             EPWM_SOC_A, EPWM_SOC_TBCTR_D_CMPC);

    EPWM_enableADCTrigger(obj->pwmHandle[0], EPWM_SOC_A);

    // ADC SOC trigger for the 1st dc-link current sampling
    EPWM_setADCTriggerSource(obj->pwmHandle[1],
                                 EPWM_SOC_A,
                                 EPWM_SOC_TBCTR_U_CMPC);

    EPWM_enableADCTrigger(obj->pwmHandle[1], EPWM_SOC_A);

    // ADC SOC trigger for the 2nd dc-link current sampling
    EPWM_setADCTriggerSource(obj->pwmHandle[1],
                             EPWM_SOC_B,
                             EPWM_SOC_TBCTR_U_CMPD);

    EPWM_enableADCTrigger(obj->pwmHandle[1], EPWM_SOC_B);

    // ADC SOC trigger for the 3rd dc-link current sampling
    EPWM_setADCTriggerSource(obj->pwmHandle[2],
                                 EPWM_SOC_A,
                                 EPWM_SOC_TBCTR_D_CMPC);

    EPWM_enableADCTrigger(obj->pwmHandle[2], EPWM_SOC_A);

    // ADC SOC trigger for the 4th dc-link current sampling
    EPWM_setADCTriggerSource(obj->pwmHandle[2],
                             EPWM_SOC_B,
                             EPWM_SOC_TBCTR_D_CMPD);

    EPWM_enableADCTrigger(obj->pwmHandle[2], EPWM_SOC_B);
#else   //!(MOTOR1_ISBLDC || MOTOR1_DCLINKSS)
    // setup the Event Trigger Selection Register (ETSEL)
    EPWM_setInterruptSource(obj->pwmHandle[0], EPWM_INT_TBCTR_ZERO);

    EPWM_enableInterrupt(obj->pwmHandle[0]);

    EPWM_setADCTriggerSource(obj->pwmHandle[0],
                             EPWM_SOC_A, EPWM_SOC_TBCTR_D_CMPC);

    EPWM_enableADCTrigger(obj->pwmHandle[0], EPWM_SOC_A);
#endif  // !(MOTOR1_ISBLDC || MOTOR1_DCLINKSS)

    // setup the Event Trigger Prescale Register (ETPS)
    if(numPWMTicksPerISRTick > 15)
    {
        numPWMTicksPerISRTick = 15;
    }
    else if(numPWMTicksPerISRTick < 1)
    {
        numPWMTicksPerISRTick = 1;
    }

    EPWM_setInterruptEventCount(obj->pwmHandle[0], numPWMTicksPerISRTick);

    EPWM_setADCTriggerEventPrescale(obj->pwmHandle[0], EPWM_SOC_A,
                                    numPWMTicksPerISRTick);
    EPWM_setADCTriggerEventPrescale(obj->pwmHandle[0], EPWM_SOC_B,
                                    numPWMTicksPerISRTick);

#if defined(MOTOR1_DCLINKSS)
    EPWM_setADCTriggerEventPrescale(obj->pwmHandle[1], EPWM_SOC_A,
                                    numPWMTicksPerISRTick);
    EPWM_setADCTriggerEventPrescale(obj->pwmHandle[1], EPWM_SOC_B,
                                    numPWMTicksPerISRTick);

    EPWM_setADCTriggerEventPrescale(obj->pwmHandle[2], EPWM_SOC_A,
                                    numPWMTicksPerISRTick);
    EPWM_setADCTriggerEventPrescale(obj->pwmHandle[2], EPWM_SOC_B,
                                    numPWMTicksPerISRTick);
#endif  //MOTOR1_DCLINKSS

    // setup the Event Trigger Clear Register (ETCLR)
    EPWM_clearEventTriggerInterruptFlag(obj->pwmHandle[0]);
    EPWM_clearADCTriggerFlag(obj->pwmHandle[0], EPWM_SOC_A);
    EPWM_clearADCTriggerFlag(obj->pwmHandle[0], EPWM_SOC_B);

    // since the PWM is configured as an up/down counter, the period register is
    // set to one-half of the desired PWM period
    EPWM_setTimeBasePeriod(obj->pwmHandle[0], pwmPeriodCycles);
    EPWM_setTimeBasePeriod(obj->pwmHandle[1], pwmPeriodCycles);
    EPWM_setTimeBasePeriod(obj->pwmHandle[2], pwmPeriodCycles);

    // write the PWM data value  for ADC trigger
    EPWM_setCounterCompareValue(obj->pwmHandle[0], EPWM_COUNTER_COMPARE_C, 10);

    // write the PWM data value  for ADC trigger
#if defined(MOTOR1_DCLINKSS)
    EPWM_clearADCTriggerFlag(obj->pwmHandle[1], EPWM_SOC_A);
    EPWM_clearADCTriggerFlag(obj->pwmHandle[1], EPWM_SOC_B);

    EPWM_clearADCTriggerFlag(obj->pwmHandle[2], EPWM_SOC_A);
    EPWM_clearADCTriggerFlag(obj->pwmHandle[2], EPWM_SOC_B);

    EPWM_setCounterCompareValue(obj->pwmHandle[1],
                                EPWM_COUNTER_COMPARE_C, pwmPeriodCycles>>1);
    EPWM_setCounterCompareValue(obj->pwmHandle[1],
                                EPWM_COUNTER_COMPARE_D, pwmPeriodCycles>>1);

    EPWM_setCounterCompareValue(obj->pwmHandle[2],
                                EPWM_COUNTER_COMPARE_C, pwmPeriodCycles>>1);
    EPWM_setCounterCompareValue(obj->pwmHandle[2],
                                EPWM_COUNTER_COMPARE_D, pwmPeriodCycles>>1);

#endif  //MOTOR1_DCLINKSS


    // enable the ePWM module time base clock sync signal
    SysCtl_enablePeripheral(SYSCTL_PERIPH_CLK_TBCLKSYNC);

    return;
}  // end of HAL_setupPWMs() function

over 1 year ago

0 Yanming Luo over 1 year ago

TI__Guru** 109740 points

No. You can't change the system clock to 200Mhz for F280025C. The maximum system clock is 100MHz for F280025C. If you need a C2000 with 200MHz, you should select the F2837x or F2838x device.

Actually, the 100MHz F28002x, or 120MHZ F28003x is good enough for 50KHz PWM, you may just need to decimate the control ISR frequency to 25KHz.

0 Jagbir over 1 year ago in reply to Yanming Luo

Expert 1515 points

Hi Yanming,

I am using a custom board based on F28379s with a clock of 200Mhz.

Thanks,

Jagbir

0 Yanming Luo over 1 year ago in reply to Jagbir

TI__Guru** 109740 points

OK. You can refer to the device.c and device.h files for F28379s in C2000Ware to configure the PLL according to the crystal/oscillator used on the board.

BTW, the PWM clock is still 100MHz on F28379s even you set its system clock to 200MHz. Please take a look at the datasheet and TRM of F28379s tohave more details about EPWM clock on F28379s.

0 Jagbir over 1 year ago in reply to Yanming Luo

Expert 1515 points

I have set the EPWM clock on F28379 as 100MHz. Based on that my value of TBPRD comes out to be 1000 with CMPAs of 500. My ISR is every 20uS(50KHz PWM). I can run the motor only at low speeds. Below are the issues I am facing.

My ADC conversion is not in the middle of the PWM/current waveform
The current waveform is not sinusoidal.

Question:

Is my TBPRD calculation correct
Why is my ADC conversion not in the middle of the current waveform.

0 Yanming Luo over 1 year ago in reply to Jagbir

TI__Guru** 109740 points

Jagbir said:
Is my TBPRD calculation correct

Yes, it's right.

Jagbir said:
Why is my ADC conversion not in the middle of the current waveform.

Which inverter board and build level are you using? The ADC sampling is trigger at the TBCNT=zero every PWM period.

You should zoom out the current waveform to see if the current waveform is a similar sinusoidal shape with the motor running electrical frequency.

0 Jagbir over 1 year ago in reply to Yanming Luo

Expert 1515 points

Yanming Luo said:
Which inverter board and build level are you using

I am using DRV8323RS.

Yanming Luo said:
You should zoom out the current waveform to see if the current waveform is a similar sinusoidal shape with the motor running electrical frequency.

The current waveform is not sinusoidal. It is triangular in shape.

0 Yanming Luo over 1 year ago in reply to Jagbir

TI__Guru** 109740 points

The current waveform is dependent on the BEMF shape that could be similar as sinusoidal, not a ideal sinusoidal on some of the motor.

You may try to set the time of the oscilloscope to 10ms to monitor the motor phase current.

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LAUNCHXL-F280025C: Universal motor lab: Using a higher system clock