TMS320F28379D: Is it possible to enable both TBPRDHR and CMPAHR at the same time?

Hi Ito,

I just put together some code using our existing examples to implement duty control and period control in a highly simplified manner. Only EPWM1 module is used (both channel A and B), CMPxHR values are left constant (able to be changed by the user), and TBPRDHR is very slowly incremented.

I'd recommend you import an existing example (such as {C2000Ware}\driverlib\f2837xd\examples\cpu1\hrpwm\hrpwm_ex4_duty_updown_sfo) into CCS and then replace the hrpwm_ex4_duty_updown_sfo.c file contents with what I have below. Hope this helps show what settings you should implement!

//#############################################################################
//
// FILE:   hrpwm_simple_duty_and_period_control_updown_sfo.c
//
// TITLE:  HRPWM DUTY and PERIOD CONTROL (simplified).
//
//#############################################################################
//
// This is a simplified HRPWM example where HRPWM duty control and
// HRPWM period control capability are both already set up for you on only
// one PWM module (EPWM1). This example uses CMPAHR, CMPBHR, and TBPRDHR to show the
// implementation of HR duty and period modulation together. The user can alter
// CMPAHR and CMPBHR values during run time in the register viewing window of CCS.
// the example slowly increments the TBPRDHR value to increase the TBPRDHR value.
// You can see the outputs of channels EPWM1A and EPWM1B change on an oscilloscope.
// Increasing CMPxHR values will decrease the duty cycle of channel 'x'.
// The incrementing of TBPRDHR will lower the frequency by lengthening the period of both channels.
//
// Period is incremented by default. To adjust the duty cycle while running the code:
// 1. Open the Registers window in CCS.
// 2. Turn on Continuous Refresh using the yellow arrows button.
// 3. Scroll to EPWM1 registers and expand them.
// 4. Find the CMPA and CMPB registers. Click the arrow to expand them so you see the HR elements.
// 5. Right-click on CMPAHR and CMPBHR and change the number formats to Hex for readability.
// 6. Double-click on the CMPAHR or CMPBHR register and change the value from 0x0100 to 0xFF00.
// This changes the CMPxHR value from 1 to the max (255). Maxing out CMPxHR to 255 should result
// in a 1-clock-cycle change.
//
// From here, you can continue to alter the HR numbers as needed for HR duty and period control.
//
//
//#############################################################################
//
// Included Files
//
#include "driverlib.h"
#include "device.h"
#include "board.h"
#include "SFO_V8.h"

//
// Defines
//
#define EPWM_TIMER_TBPRD    100UL           // TBPRD value for this example is set to 100
#define LAST_EPWM_INDEX_FOR_EXAMPLE    2    // Used for the EPWM initialization function

//
// Globals
//

float32_t periodFine = 0.20; //HRPWM period percentage
uint16_t status;

int MEP_ScaleFactor; // Global variable used by the SFO library
                     // Result can be used for all HRPWM channels
                     // This variable is also copied to HRMSTEP
                     // register by SFO() function.

//
// Store the EPWM1 'base' name here (can append other EPWM modules as needed)
//
volatile uint32_t ePWM[] = {0, myEPWM1_BASE};

//
// Function Prototypes
//
void initHRPWM(uint32_t period);
void error(void);
__interrupt void epwm1ISR(void);


//
// Main
//
void main(void)
{
    //
    // Initialize device clock and peripherals
    //
    Device_init();

    //
    // Disable pin locks and enable internal pull ups.
    //
    Device_initGPIO();

    //
    // Initialize PIE and clear PIE registers. Disables CPU interrupts.
    //
    Interrupt_initModule();

    //
    // Initialize the PIE vector table with pointers to the shell Interrupt
    // Service Routines (ISR).
    //
    Interrupt_initVectorTable();

    //
    // Assign the interrupt service routines to ePWM interrupts
    //
    Interrupt_register(INT_EPWM1, &epwm1ISR);


    //
    // Initialize the EPWM GPIOs and change XBAR inputs from using GPIO0
    // This will implement any SysConfig configurations. Note that any configurations
    // that occur after this will overwrite your SysConfig configurations.
    //
    Board_init();

    //
    // Calling SFO() updates the HRMSTEP register with calibrated MEP_ScaleFactor.
    // HRMSTEP must be populated with a scale factor value prior to enabling
    // high resolution period control.
    //
    while(status == SFO_INCOMPLETE)
    {
        status = SFO();
        if(status == SFO_ERROR)
        {
            error();   // SFO function returns 2 if an error occurs & # of MEP
        }              // steps/coarse step exceeds maximum of 255.
    }

    //
    // Disable sync(Freeze clock to PWM as well)
    //
    SysCtl_disablePeripheral(SYSCTL_PERIPH_CLK_TBCLKSYNC);


    //
    // Initialize the EPWM1 module in code with PRD set to EPWM_TIMER_TBPRD (in this example, 100)
    //
    initHRPWM(EPWM_TIMER_TBPRD);

    //
    // Enable sync and clock to PWM
    //
    SysCtl_enablePeripheral(SYSCTL_PERIPH_CLK_TBCLKSYNC);


    // Enable ePWM interrupts
    //
    Interrupt_enable(INT_EPWM1);


    //
    // Enable Global Interrupt (INTM) and realtime interrupt (DBGM)
    //
    EINT;
    ERTM;


    for(;;)
    {
        //
        // Apply HRPWM Period Control (slowly increments 0.2 to 0.9 in 0.1 steps, then starts over)
        //
        for(periodFine = 0.2; periodFine < 0.9; periodFine += 0.1)
        {
            DEVICE_DELAY_US(1000000);
            uint16_t i = 0;

            for(i=1; i<LAST_EPWM_INDEX_FOR_EXAMPLE; i++)
            {
                float32_t count = ((EPWM_TIMER_TBPRD-1) << 8UL) + (float32_t)(periodFine * 256);
                uint32_t compCount = count;
                HRPWM_setTimeBasePeriod(ePWM[i], compCount);
            }

            //
            // Call the scale factor optimizer lib function SFO()
            // periodically to track for any change due to temp/voltage.
            // This function generates MEP_ScaleFactor by running the
            // MEP calibration module in the HRPWM logic. This scale
            // factor can be used for all HRPWM channels. The SFO()
            // function also updates the HRMSTEP register with the
            // scale factor value.
            //
            status = SFO(); // in background, MEP calibration module
                                 // continuously updates MEP_ScaleFactor

            if (status == SFO_ERROR)
            {
                error();   // SFO function returns 2 if an error occurs & #
                                // of MEP steps/coarse step
            }              // exceeds maximum of 255.
        }
    }
}

//
// Define the EPWM1 ISR
//
__interrupt void epwm1ISR(void)
{
    //
    // This is left empty for the user to fill as needed
    //

    EPWM_clearEventTriggerInterruptFlag(EPWM1_BASE); // Clear the interrupt flag from the PWM module
    Interrupt_clearACKGroup(INTERRUPT_ACK_GROUP3); // Acknowledge the EPWM interrupt group in the PIE to reset the ACK bit
}

//
// Initialize your EPWM1 module as with HR configurations (PRD is function input)
//
void initHRPWM(uint32_t period)
{
    uint16_t j;

    // Parse through all EPWM modules you want this to apply to. In this case, only EPWM1 will be initalized.

    for (j=1;j<LAST_EPWM_INDEX_FOR_EXAMPLE;j++)
    {
        //
        // Set PWM mode to free run so that debugger does not stop it
        //
        EPWM_setEmulationMode(ePWM[j], EPWM_EMULATION_FREE_RUN);

        //
        // Set-up TBCLK
        //
        EPWM_setPeriodLoadMode(ePWM[j], EPWM_PERIOD_SHADOW_LOAD);
        EPWM_setTimeBasePeriod(ePWM[j], period-1);
        EPWM_setPhaseShift(ePWM[j], 0U);
        EPWM_setTimeBaseCounter(ePWM[j], 0U);

        //
        // Set up base duty to be 50% (CMPx = 50, TBPRD = 100)
        // Initialize CMPxHR values to be 1 (these are within the CMPA and CMPB registers, but must be written to in a particular way as shown below.
        //
        HRPWM_setCounterCompareValue(ePWM[j], HRPWM_COUNTER_COMPARE_A, (period/2 << 8) + 1);
        HRPWM_setCounterCompareValue(ePWM[j], HRPWM_COUNTER_COMPARE_B, (period/2 << 8) + 1);


        //
        // Set up counter mode to be up-down counter mode
        //
        EPWM_setTimeBaseCounterMode(ePWM[j], EPWM_COUNTER_MODE_UP_DOWN);

        //
        // Disable phase shifting
        //
        EPWM_disablePhaseShiftLoad(ePWM[j]);

        //
        // Set up both EPWM1 clock dividers and disable sync out pulses
        //
        EPWM_setClockPrescaler(ePWM[j],
                               EPWM_CLOCK_DIVIDER_1,
                               EPWM_HSCLOCK_DIVIDER_1);
        EPWM_setSyncOutPulseMode(ePWM[j], EPWM_SYNC_OUT_PULSE_DISABLED);

        //
        // Set up shadowing
        // MUST BE CTR=(ZER & PRD)
        //
        EPWM_setCounterCompareShadowLoadMode(ePWM[j],
                                             EPWM_COUNTER_COMPARE_A,
                                             EPWM_COMP_LOAD_ON_CNTR_ZERO_PERIOD);
        EPWM_setCounterCompareShadowLoadMode(ePWM[j],
                                             EPWM_COUNTER_COMPARE_B,
                                             EPWM_COMP_LOAD_ON_CNTR_ZERO_PERIOD);

        //
        // Set up Action Qualifiers for Channels A and B
        // (set high on CMPxU, set low on CMPxD for both channels)
        //

        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);
        EPWM_setActionQualifierAction(ePWM[j],
                                      EPWM_AQ_OUTPUT_B,
                                      EPWM_AQ_OUTPUT_HIGH,
                                      EPWM_AQ_OUTPUT_ON_TIMEBASE_UP_CMPB);
        EPWM_setActionQualifierAction(ePWM[j],
                                      EPWM_AQ_OUTPUT_B,
                                      EPWM_AQ_OUTPUT_LOW,
                                      EPWM_AQ_OUTPUT_ON_TIMEBASE_DOWN_CMPB);

        //
        // Select Channel A and B control mode to utilize CMPxHR or TBPRDHR
        //
        HRPWM_setMEPControlMode(ePWM[j], HRPWM_CHANNEL_A, HRPWM_MEP_DUTY_PERIOD_CTRL);
        HRPWM_setMEPControlMode(ePWM[j], HRPWM_CHANNEL_B, HRPWM_MEP_DUTY_PERIOD_CTRL);

        //
        // Select Channel A and B edge mode to control both edges
        //
        HRPWM_setMEPEdgeSelect(ePWM[j], HRPWM_CHANNEL_A, HRPWM_MEP_CTRL_RISING_AND_FALLING_EDGE);
        HRPWM_setMEPEdgeSelect(ePWM[j], HRPWM_CHANNEL_B, HRPWM_MEP_CTRL_RISING_AND_FALLING_EDGE);

        //
        // Set up shadow loading for CMPAHR (this MUST be set to shadow load on CTR=(ZER & PRD))
        //
        HRPWM_setCounterCompareShadowLoadEvent(ePWM[j], HRPWM_CHANNEL_A, HRPWM_LOAD_ON_CNTR_ZERO_PERIOD);
        HRPWM_setCounterCompareShadowLoadEvent(ePWM[j], HRPWM_CHANNEL_B, HRPWM_LOAD_ON_CNTR_ZERO_PERIOD);

        //
        // Turn on auto-conversion
        //
        HRPWM_enableAutoConversion(ePWM[j]);

        //
        // Turn on high-resolution period control in order to let HR duty control occur on BOTH EDGEs.
        //
        HRPWM_enablePeriodControl(ePWM[j]);
        HRPWM_disablePhaseShiftLoad(ePWM[j]);


        //
        // Set up an empty interrupt where user can fill with whatever is desired
        // Select INT on Time base counter zero event,
        // Enable INT, generate INT on 1st event
        //
        EPWM_setInterruptSource(ePWM[j], EPWM_INT_TBCTR_ZERO);
        EPWM_enableInterrupt(ePWM[j]);
        EPWM_setInterruptEventCount(ePWM[j], 1U);

        //
        // Turn on high-resolution period control.
        //

        HRPWM_enablePeriodControl(ePWM[j]);
        HRPWM_enablePhaseShiftLoad(ePWM[j]);

        EPWM_forceSyncPulse(ePWM[j]);
    }

}

//
// error - Halt debugger when called
//
void error (void)
{
    ESTOP0;         // Stop here and handle error
}

Best Regards,

Allison