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Interrupting mainISR

Kevin Bontrager
Prodigy 70 points

Hi,

I'm working on an SPI controlled motor controller using a TMS320F28069. The mainISR where the controller runs from takes about 50-60us to complete. My SPI data needs to be moved from the RxFifo to a buffer every 4 words or I will get an overflow and loose data. To prevent that I want to interrupt the mainISR with my SPI ISR. My question is this, is it a good idea to interrupt the mainISR to service the SPI? Are there certain function calls in the mainISR that should not be interrupted?

Thanks,

Kevin

  • 0
    TI__Guru** 118000 points
    Kevin,
    I moved this to the C2000 forum to get a faster / better response.
    e2e.ti.com/.../449319


    I know in general though you shouldn't interrupt the fastest ISR that is running off your ADC conversion done data for your control loop.
  • 0 in reply to ChrisClearman
    Prodigy 70 points

    My question is more one of motor control I believe. I'm wondering if delaying any of this by interrupting it will have adverse effects on motor performance.

    Here is my mainISR

    interrupt void mainISR(void)
{
	ENABLE_INTERRUPTS;
	static uint16_t stCnt = 0;
	CTRL_Obj *obj = (CTRL_Obj *)ctrlHandle;
	ST_Obj *stObj = (ST_Obj *)stHandle;

  // toggle status LED
  if(gLEDcnt++ > (uint_least32_t)(USER_ISR_FREQ_Hz / LED_BLINK_FREQ_Hz))
  {
    HAL_toggleLed(halHandle,(GPIO_Number_e)HAL_Gpio_LED2);
    gLEDcnt = 0;
  }

  if(stCnt++ >= ISR_TICKS_PER_SPINTAC_TICK) {
	ST_runPosConv(stHandle, encHandle, ctrlHandle);
	ST_runVelCtl(stHandle, ctrlHandle);
	stCnt = 1;
  }
  
  if(gVariables.userControlMode == current_mode)
  {
	 gMotorVars.IqRef_A = gVariables.set_current;
  }
  else if(gVariables.userControlMode == velocity_mode)
  {
	  gMotorVars.IqRef_A = _IQmpy(STVELCTL_getTorqueReference(stObj->velCtlHandle), _IQ(USER_IQ_FULL_SCALE_CURRENT_A));
  }

  // update Iq reference
  updateIqRef(ctrlHandle);

  // compute the electrical angle
  ENC_calcElecAngle(encHandle, HAL_getQepPosnCounts(halHandle));

  // acknowledge the ADC interrupt
  HAL_acqAdcInt(halHandle,ADC_IntNumber_1);

  // convert the ADC data
  HAL_readAdcData(halHandle,&gAdcData);

  // Run the SpinTAC Components
  CTRL_run(ctrlHandle,halHandle,&gAdcData,&gPwmData,ENC_getElecAngle(encHandle));

  // write the PWM compare values
  HAL_writePwmData(halHandle,&gPwmData);

  // setup the controller
  CTRL_setup(ctrlHandle);

  // if we are forcing alignment, using the Rs Recalculation, align the eQEP angle with the rotor angle
  if((EST_getState(obj->estHandle) == EST_State_Rs) && (USER_MOTOR_TYPE == MOTOR_Type_Pm)) //TODO figure this out
  {
	  ENC_setZeroOffset(encHandle, (uint32_t)(HAL_getQepPosnMaximum(halHandle) - HAL_getQepPosnCounts(halHandle)));
  }
  GPIO_setLow(halHandle->gpioHandle, GPIO_Number_29);
  return;
} // end of mainISR() function

  • 0 in reply to Kevin Bontrager
    TI__Guru** 118000 points
    yes, this is probably an issue to have anything that can interrupt the main control loop.
    it is critical in a closed loop application that you have samples from a known time that get processed to create a control output.

    if your serial interrupt were of a known small amount of time perhaps you could fit it in without issues, but this certainly is NOT recommended.