ePWM, Trip zone and analog comparator

Hi JHi,

Did you find a solution for this problem - I am struggling over a similar issue. I use the comparator to sense a current and issue an interrupt when the current is bigger than the threshold, when the current is smaller again, another interrupt should be called. The problem is, that the interrupt is called over and over again as soon as the current value is bigger than the threshold, that drives me nuts. Any proposals would be greatly appreciated!

BR andreas

In your case you could use digital compare. First configure it trigger to when digital compare is high. When you then service your interrupt change the trigger to when the digital compare is low. Now you should only get one interrupt and when the current decreases under your threshold and you get another interrupt, change the trigger back to digital compare high. Do you think this could work?

JHi

Hi JHi

Thanks for the proposal, I do agree with you that this should be a useful solution, however for some reasons I am not able to implement it on the target.... Something in my configuration is wrong. This submodule is definitly not the one that has the best description..... I'll try again, if you or anybody else could give me hints, go on they are welcome :-)

BR Andreas

Example:

EPwm1Regs.TZDCSEL.bit.DCAEVT2 = 2; // DCAH = high, DCAL = don't care

EPwm1Regs.DCTRIPSEL.bit.DCAHCOMPSEL = 8; Digital Compare A High Input Select, COMP1OUT input

EPwm1Regs.DCACTL.bit.EVT2FRCSYNCSEL = 1; // Source Is Asynchronous Signal

EPwm1Regs.TZEINT.bit.DCAEVT2 = 1; Digital Comparator Output A Event 2 Interrupt Enable

in first interrupt

EPwm1Regs.TZDCSEL.bit.DCAEVT2 = 1; // DCAH = low, DCAL = don't care

and back again second interrupt:

EPwm1Regs.TZDCSEL.bit.DCAEVT2 = 2; // DCAH = high, DCAL = don't care

I hope I have everything here :)

Edit: You will also have to enable the TZ interrupt :

PieCtrlRegs.PIEIER2.bit.INTx1 = 1;              // Enable INT 2.1 in the PIE

Hi JHi

OK I'm there now - the config you proposed is correct. What you have to do in in addition in the TZ ISR, is to poll the status bit of the comparator and take the action according, see the example below. Thanks very much for the support!

BR Andreas

interrupt void EPWM3_TZINT_ISR(void)    // EPwm3 Trip Zone
{
  // Set interrupt priority:
  volatile Uint16 TempPIEIER = PieCtrlRegs.PIEIER2.all;
  IER |= M_INT2;
  IER    &= MINT2;                         // Set "global" priority
  PieCtrlRegs.PIEIER2.all &= MG23;   // Set "group"  priority
  PieCtrlRegs.PIEACK.all = 0xFFFF;   // Enable PIE interrupts
  EINT;

  if(Comp1Regs.COMPSTS.bit.COMPSTS == 1)
  {
    EALLOW;
    EPwm3Regs.TZDCSEL.bit.DCAEVT2 = 0x1;
    GpioDataRegs.GPASET.bit.GPIO4 = 1;
  }
  else
  {
    EALLOW;
    EPwm3Regs.TZDCSEL.bit.DCAEVT2 = 0x2;
    GpioDataRegs.GPACLEAR.bit.GPIO4 = 1;
  }
   
  EPwm3Regs.TZCLR.bit.INT = 1;
  EPwm3Regs.TZCLR.bit.DCAEVT2 = 1;
  EDIS;
   
  // Restore registers saved:
  DINT;
  PieCtrlRegs.PIEIER2.all = TempPIEIER;

  // Next two lines for debug only to halt the processor here
  // Remove after inserting ISR Code
  //asm ("      ESTOP0");
  //for(;;);
}

Hi JHi

OK I'm there now - the config you proposed is correct. What you have to do in in addition in the TZ ISR, is to poll the status bit of the comparator and take the action according, see the example below. Thanks very much for the support!

BR Andreas

interrupt void EPWM3_TZINT_ISR(void)    // EPwm3 Trip Zone
{
  // Set interrupt priority:
  volatile Uint16 TempPIEIER = PieCtrlRegs.PIEIER2.all;
  IER |= M_INT2;
  IER    &= MINT2;                         // Set "global" priority
  PieCtrlRegs.PIEIER2.all &= MG23;   // Set "group"  priority
  PieCtrlRegs.PIEACK.all = 0xFFFF;   // Enable PIE interrupts
  EINT;

  if(Comp1Regs.COMPSTS.bit.COMPSTS == 1)
  {
    EALLOW;
    EPwm3Regs.TZDCSEL.bit.DCAEVT2 = 0x1;
    GpioDataRegs.GPASET.bit.GPIO4 = 1;
  }
  else
  {
    EALLOW;
    EPwm3Regs.TZDCSEL.bit.DCAEVT2 = 0x2;
    GpioDataRegs.GPACLEAR.bit.GPIO4 = 1;
  }
   
  EPwm3Regs.TZCLR.bit.INT = 1;
  EPwm3Regs.TZCLR.bit.DCAEVT2 = 1;
  EDIS;
   
  // Restore registers saved:
  DINT;
  PieCtrlRegs.PIEIER2.all = TempPIEIER;

  // Next two lines for debug only to halt the processor here
  // Remove after inserting ISR Code
  //asm ("      ESTOP0");
  //for(;;);
}