Hardware Timer Implementation

[M. Schuurmans]

Hello everyone. I have currently started to work with the NRF5340 chipsets. One of the first tasks that were assigned to me is to implement a singlewire software protocol. To get I need precise timing to get the device working. In the range of nanoseconds. My current implementation looks like this: 

#include "nrfx_timer.h"
#include <zephyr/drivers/gpio.h>
#include <zephyr/devicetree.h>
#include <zephyr/device.h>

void timer_init()
{
  // Initialize HF Clock
  NRF_CLOCK->TASKS_HFCLKSTART = 1;

  // Initialize Timer
  NRF_TIMER1->MODE = TIMER_MODE_MODE_Timer;
  NRF_TIMER1->TASKS_CLEAR = 1;
  NRF_TIMER1->PRESCALER = NRF_TIMER_FREQ_1MHz;
  NRF_TIMER1->BITMODE = TIMER_BITMODE_BITMODE_32Bit;
  NRF_TIMER1->INTENSET = (TIMER_INTEN_COMPARE0_Enabled << TIMER_INTENSET_COMPARE0_Pos);

}

//
//  Delay function for constant 1-Wire timings
//
void OneWire_Delay(uint32_t us)
{
  // Reset compare register
  NRF_TIMER1->EVENTS_COMPARE[0] = 0;
  // Reset capture compare
  NRF_TIMER1->CC[0] = us;
  // Reset timer
  NRF_TIMER1->TASKS_CLEAR = 1;
  NRF_TIMER1->TASKS_STOP = 0;
  NRF_TIMER1->TASKS_START = 1;

  while(!NRF_TIMER1->EVENTS_COMPARE[0])
  {
    __NOP();
    // Busy wait
  }

  NRF_TIMER1->TASKS_STOP = 1;
  NRF_TIMER1->TASKS_CLEAR = 1;
}

static const struct gpio_dt_spec gpio27 = GPIO_DT_SPEC_GET(GPIO0_NODE, gpios);

void main(void)
{
  timer_init();

  for(;;)
  {
    OneWire_Delay((uint32_t)1000);
    gpio_pin_toggle_dt(gpio27);
  }
}

The pin toggles on and off as expected within 1ms. Afterwards the system waits for 400ms untill it starts again. Is something wrong with my implementation? Is this a good approach to the problem?

Best regards Maikel