TIMER and PWL why doesn't TASKS_CLEAR work?

Question

I'm trying to generate a 1kHz PWL and call a function every 1ms the code is below. My initial though was to set TASKS_CLEAR once the timer reached the max pwl value. Oddly this worked of the reset value was 32,000 but not 256. I think I have fixed it by using the "SHORTS" function to clear the timer, but I'd like to know why using clear did not work. The BLE was disabled during the test.

I want to use this chip to control a sensored brushless motor (with ble off when the motor is running, will I able to get enough through put).

Using this chip has become a real pain. So many poorly documented issues.

void timers_init2(void){
  nrf_gpio_cfg_output(3);
  // Start 16 MHz crystal oscillator .                                                                                                       
  NRF_CLOCK->EVENTS_HFCLKSTARTED = 0;
  NRF_CLOCK->TASKS_HFCLKSTART    = 1;

  // Wait for the external oscillator to start up.                                                                                           
  while (NRF_CLOCK->EVENTS_HFCLKSTARTED == 0)
    {
      //Do nothing.                 
    }

  NRF_TIMER2->TASKS_STOP = 1;// Stop timer               
  NRF_TIMER2->MODE =TIMER_MODE_MODE_Timer;

  NRF_TIMER2->TASKS_CLEAR = 1;
  NRF_TIMER2->PRESCALER = 6; // max=9   6 gives 250khz         
  NRF_TIMER2->BITMODE = TIMER_BITMODE_BITMODE_16Bit; // 8 bit mode does not work            
  NRF_TIMER2->CC[0]=256; //reset value                   
  NRF_TIMER2->CC[1]=m.pwm;
           
  NRF_TIMER2->INTENSET = (TIMER_INTENSET_COMPARE0_Enabled << TIMER_INTENSET_COMPARE0_Pos)
  |    (TIMER_INTENSET_COMPARE1_Enabled<< TIMER_INTENSET_COMPARE1_Pos);

  NRF_TIMER2->SHORTS = (TIMER_SHORTS_COMPARE0_CLEAR_Enabled << TIMER_SHORTS_COMPARE0_CLEAR_Pos);

  NVIC_EnableIRQ(TIMER2_IRQn);

  NRF_TIMER2->TASKS_START = 1;

}

void TIMER2_IRQHandler(void){

  if((NRF_TIMER2->EVENTS_COMPARE[0] != 0) 
       && ((NRF_TIMER2->INTENSET & TIMER_INTENSET_COMPARE0_Msk) !=0)){

    // reset timer and start pulse                  
    NRF_TIMER2->EVENTS_COMPARE[0] = 0;
    //NRF_TIMER2->TASKS_CLEAR; // needed to replace this with shorts call above 
     call_func_every_ms();
    if(m.pwm> 0) {
      NRF_TIMER2->CC[1]=m.pwm;           
    }
      nrf_gpio_pin_set(3);
  }
if((NRF_TIMER2->EVENTS_COMPARE[1] !=0) 
       && ((NRF_TIMER2->INTENSET & TIMER_INTENSET_COMPARE1_Msk) !=0)){

    // End of pwm pulse            

    NRF_TIMER2->EVENTS_COMPARE[1] = 0;
    nrf_gpio_pin_clear(3);
  }

Ole Bauck · Accepted Answer

Change NRF_TIMER2->TASKS_CLEAR; to NRF_TIMER2->TASKS_CLEAR = 1;