TMS320F28379D: F2837 ecap captures two channel PWM

Hi,

I don't think there is any such priority between the two ECAP modules. Are you resetting the counters of both capture modules at same time stamp ? It would be easier to debug if you can share the software configuration that you are using.

Regards

Himanshu

thank you so much for your reply, my software configuration as bellow:

void main(void)
{
   InitSysCtrl();

   InitECap1Gpio(20);       //inc a
   GPIO_SetupPinOptions(20, GPIO_INPUT, GPIO_ASYNC);

   InitECap2Gpio(21);       //inc b
   GPIO_SetupPinOptions(21, GPIO_INPUT, GPIO_ASYNC);

   DINT;
   InitPieCtrl();
   IER = 0x0000;
   IFR = 0x0000;
   InitPieVectTable();

   EALLOW;
   PieVectTable.ECAP1_INT = &ecap1_isr;
   PieVectTable.ECAP2_INT = &ecap2_isr;
   EDIS;

   InitECapture();

   IER |= M_INT4;
   PieCtrlRegs.PIEIER4.bit.INTx1 = 1;
   PieCtrlRegs.PIEIER4.bit.INTx2 = 1;

   EINT;
   ERTM;

   for(;;)
   {
      asm("          NOP");
   }
}


void InitECapture()
{
   ECap1Regs.ECCTL1.bit.CAP1POL = 0;      //rising
   ECap1Regs.ECCTL1.bit.CAP2POL = 1;      //fall
   ECap1Regs.ECCTL1.bit.CAP3POL = 0;      //rising
   ECap1Regs.ECCTL1.bit.CAP4POL = 1;      //fall

   ECap1Regs.ECCTL1.bit.CTRRST1 = 0;       // abs
   ECap1Regs.ECCTL1.bit.CTRRST2 = 0;       // abs
   ECap1Regs.ECCTL1.bit.CTRRST3 = 0;       // abs
   ECap1Regs.ECCTL1.bit.CTRRST4 = 0;       // abs

   ECap1Regs.ECCTL1.bit.CAPLDEN = 1;       // Enable capture units
   ECap1Regs.ECCTL1.bit.PRESCALE = 0;      // /1

   ECap1Regs.ECCTL2.bit.CAP_APWM = 0;      //capture mode
   ECap1Regs.ECCTL2.bit.CONT_ONESHT = 0;   //continuous mode

   ECap1Regs.ECEINT.all = 0x0000;
   ECap1Regs.ECCLR.all = 0xFFFF;
   ECap1Regs.ECCTL2.bit.TSCTRSTOP = 1;     // Start Counter
   ECap1Regs.ECEINT.bit.CEVT4 = 1;         // 4 events = __interrupt

   ECap2Regs.ECCTL1.bit.CAP1POL = 0;      //rising
   ECap2Regs.ECCTL1.bit.CAP2POL = 1;      //fall
   ECap2Regs.ECCTL1.bit.CAP3POL = 0;      //rising
   ECap2Regs.ECCTL1.bit.CAP4POL = 1;      //fall

   ECap2Regs.ECCTL1.bit.CTRRST1 = 0;       // abs
   ECap2Regs.ECCTL1.bit.CTRRST2 = 0;       // abs
   ECap2Regs.ECCTL1.bit.CTRRST3 = 0;       // abs
   ECap2Regs.ECCTL1.bit.CTRRST4 = 0;       // abs

   ECap2Regs.ECCTL1.bit.CAPLDEN = 1;       // Enable capture units
   ECap2Regs.ECCTL1.bit.PRESCALE = 0;      // /1

   ECap2Regs.ECCTL2.bit.CAP_APWM = 0;      //capture mode
   ECap2Regs.ECCTL2.bit.CONT_ONESHT = 0;   //continuous mode

   ECap1Regs.ECCTL2.bit.SYNCI_EN = 1;
   ECap1Regs.ECCTL2.bit.SYNCO_SEL =0;
   ECap2Regs.ECCTL2.bit.SYNCI_EN = 1;
   ECap2Regs.ECCTL2.bit.SYNCO_SEL =0;

   ECap1Regs.ECCTL2.bit.SWSYNC=1;
   ECap2Regs.ECCTL2.bit.SWSYNC=0;

   EALLOW;
   InputXbarRegs.INPUT5SELECT = 0x51;
   GpioDataRegs.GPBDAT.bit.GPIO51 = 0;
   SyncSocRegs.SYNCSELECT.bit.ECAP1SYNCIN = 0x5;
   EDIS;

   ECap2Regs.ECEINT.all = 0x0000;
   ECap2Regs.ECCLR.all = 0xFFFF;
   ECap2Regs.ECCTL2.bit.TSCTRSTOP = 1;     // Start Counter
   ECap2Regs.ECEINT.bit.CEVT4 = 1;         // 4 events = __interrupt
}


__interrupt void ecap1_isr(void)
{
   a_rise_time1 = ECap1Regs.CAP1;
   a_fall_time1 = ECap1Regs.CAP2;
   a_rise_time2 = ECap1Regs.CAP3;
   a_fall_time2 = ECap1Regs.CAP4;

   ECap1Regs.ECCLR.all = 0xFFFF;
   PieCtrlRegs.PIEACK.all = PIEACK_GROUP4;
}

__interrupt void ecap2_isr(void)
{
   b_rise_time1 = ECap2Regs.CAP1;
   b_fall_time1 = ECap2Regs.CAP2;
   b_rise_time2 = ECap2Regs.CAP3;
   b_fall_time2 = ECap2Regs.CAP4;

  phase_ab1 =   a_rise_time1 - b_rise_time1;
  phase_ab2 =   a_fall_time1 - b_fall_time1;

   ECap2Regs.ECCLR.all = 0xFFFF;
   PieCtrlRegs.PIEACK.all = PIEACK_GROUP4;
}

Hi,

If the incoming signal frequency is too high then it might be possible the counter for one of the ECAP module gets overflowed and which might be resulting the incorrect reading. Best way I see is to use the ECAP modules in One-shot mode and start the counters of both at the same time. And instead of measuring the difference between rising edges of both, measure the difference between the falling edges i.e. second events of ECAP. This will help in the case where the phase difference between the two signals if greater than 180 degree. You can ReArm the modules again at the end of ECAP2 interrupt.

Let me know if the suggested configuration works for you.

Regards

Himanshu

hi,

   Are the time bases of ecap1 and ecap2 synchronized? How can I configure them to synchronize?

hi,

      if i use software to synchronized ecap1 and ecap2, is this the right setting? if not , please tell me how to configure it.

      ECap1Regs.ECCTL2.bit.SWSYNC = 1;      

      ECap2Regs.ECCTL2.bit.SWSYNC = 1;