LAUNCHXL-F280039C: EPWM-1B Up Counter Output starting from zero

Hi,

I was trying to use the EPWM module in up count mode to produce the following output in EPWM1B,

I configured EPWM1 for 4kHz frequency (TBPERIOD=30000). CMPA as 50% of the period (15000) and CMPB as 75% of the period (22500).

For EPWM1A, AQ_HIGH at ZERO and AQ_LOW at CMPA.  Hence, it is producing a 50% duty 4kHz square wave. I got this done.

But for EPWM1B, AQ_HIGH at CMPA and AQ_LOW at CMPB. It should have produced a 25% duty square wave starting from the middle of the period. However, my EPWM1B is starting from zero with a 25% duty. I want it to get HIGH when time is half the period as I set CMPA=50% of PERIOD. I am observing EPWM1B and EPWM1A parallelly to see if it is coming proper.

Giving my code here,

#include "driverlib.h"
#include "device.h"

#define PWM_PERIOD 30000 // For 4kHz PWM waveform.

uint32_t PwmDuty = 15000; // Default is 50% duty cycle.
uint32_t PwmDuty_two = 22500; // Default is 75% duty cycle.

// Lab function prototypes.
inline void InitGpio(void);
inline void InitEPwm(void);

//
// Main
//

void main(void)
{
Device_init();
Interrupt_initModule();
Interrupt_initVectorTable();

InitGpio();
InitEPwm();

EINT;
ERTM;

for (;;) {
NOP;
}
}

inline void InitGpio(void)
{
Device_initGPIO();
GPIO_setPinConfig(GPIO_0_EPWM1_A);
GPIO_setPadConfig(0, GPIO_PIN_TYPE_PULLUP);
GPIO_setDirectionMode(0, GPIO_DIR_MODE_OUT);
GPIO_setPinConfig(GPIO_1_EPWM1_B);
GPIO_setPadConfig(1, GPIO_PIN_TYPE_PULLUP);
GPIO_setDirectionMode(1, GPIO_DIR_MODE_OUT);
}

inline void InitEPwm(void)
{
SysCtl_disablePeripheral(SYSCTL_PERIPH_CLK_TBCLKSYNC);
SysCtl_resetPeripheral(SYSCTL_PERIPH_RES_EPWM1);

EPWM_setClockPrescaler(EPWM1_BASE,
EPWM_CLOCK_DIVIDER_1,
EPWM_HSCLOCK_DIVIDER_1);
EPWM_setTimeBasePeriod(EPWM1_BASE, PWM_PERIOD);
EPWM_setPeriodLoadMode(EPWM1_BASE, EPWM_PERIOD_SHADOW_LOAD);
EPWM_setPhaseShift(EPWM1_BASE, 0);
EPWM_setCounterCompareValue(EPWM1_BASE,
EPWM_COUNTER_COMPARE_A,
PwmDuty);
EPWM_setCounterCompareShadowLoadMode(EPWM1_BASE,
EPWM_COUNTER_COMPARE_A,
EPWM_COMP_LOAD_ON_CNTR_ZERO_PERIOD);
EPWM_setCounterCompareValue(EPWM1_BASE,
EPWM_COUNTER_COMPARE_B,
PwmDuty_two);
EPWM_setCounterCompareShadowLoadMode(EPWM1_BASE,
EPWM_COUNTER_COMPARE_B,
EPWM_COMP_LOAD_ON_CNTR_ZERO_PERIOD);
EPWM_setActionQualifierAction(EPWM1_BASE,
EPWM_AQ_OUTPUT_A,
EPWM_AQ_OUTPUT_HIGH,
EPWM_AQ_OUTPUT_ON_TIMEBASE_ZERO);
EPWM_setActionQualifierAction(EPWM1_BASE,
EPWM_AQ_OUTPUT_A,
EPWM_AQ_OUTPUT_LOW,
EPWM_AQ_OUTPUT_ON_TIMEBASE_UP_CMPA);
EPWM_setActionQualifierAction(EPWM1_BASE,
EPWM_AQ_OUTPUT_B,
EPWM_AQ_OUTPUT_HIGH,
EPWM_AQ_OUTPUT_ON_TIMEBASE_UP_CMPA);
EPWM_setActionQualifierAction(EPWM1_BASE,
EPWM_AQ_OUTPUT_B,
EPWM_AQ_OUTPUT_LOW,
EPWM_AQ_OUTPUT_ON_TIMEBASE_UP_CMPB);
EPWM_setTimeBaseCounterMode(EPWM1_BASE, EPWM_COUNTER_MODE_UP);

SysCtl_enablePeripheral(SYSCTL_PERIPH_CLK_TBCLKSYNC);
}