compare match 4 Interrupt with EvB PWM

Hi,

I am using F2812 chip to implement the following.

1- Generate a symmetric three phase PWM, PWM7-12, using EVB on chip.

2- Map the compare match 4, CMP4, to call a software Interrupt service routine using PIE.

The first task, PWM generation, was successfully done. I have verified the physical hardware output using a scope.

However, for the second part, compare match Interrupt, I couldn’t get the expected output.

The Interrupt was delayed from the moment it should start.

My debug approach was as following.

In CMP4 Interrupt service routine, I set a hardware pin HI and maintain it for 5 micro second so I can monitor it on a scope.

For such configuration, CMP4 Hardware debug pin should go high when PWM7 goes high too.

But PWM7 was leading CMP4 hardware debug pin with big time difference, not dead-band.

Also changing the PWM ratio was only affecting the PWM7 on time period, as expected, but there was no change to the moment where CMP4 occurs.

I don’t know why this delay between the CMP4 interrupt and PWM7 goes Hi happen

void CMP4INT_isr_init(void)

{

                //Remap CMP4INT to CMP4INT_isr()

                EALLOW;

                PieVectTable.CMP4INT                                                 = &CMP4INT_isr;

                EDIS;

                //Enable CMP4INT Mask

                EvbRegs.EVBIMRA.bit.CMP4INT               = 1;

                //Reset/enable CMP4INT Flag

                EvbRegs.EVBIFRA.bit.CMP4INT     = 1;

                //Enable PIE CMP4INT in group 4

                PieCtrlRegs.PIEIER4.bit.INTx1     = 1;

                //enable Interrupt from group 4

                IER                                                                                             |= M_INT4;

}

-------------------------------------------------------------------------------------------------

interrupt void CMP4INT_isr(void)

{

                //Serve the interrupt

                // Enable more interrupts from this timer

                EvbRegs.EVBIMRA.bit.CMP4INT = 1;

                //Reset CMP4INT Flag

                EvbRegs.EVBIFRA.all |= BIT1;     

                //Acknowldge PIE from group 4

                PieCtrlRegs.PIEACK.all |= PIEACK_GROUP4;

                //Interrupt function

                GpioDataRegs.GPBDAT.bit.GPIOB6=1;  

                DELAY_US(5);

                GpioDataRegs.GPBDAT.bit.GPIOB6=0;

Could you guide me in any error I am doing in either the interrupt configuration or service function which may result in this delay?

thank you in advance.

Regards,

Bahaa