Create timer in microseconds without nrf_delay_us and __nop() / __NOP()

[Christoph_I]

Hey guys,

I have a timer like this:

const nrf_drv_timer_t TIMER_SEND_DATA = NRF_DRV_TIMER_INSTANCE(1);

static void send_protocol(void)               //function to send protocol to master
{
    // do something...
}

/**
 * @brief Handler for timer events.
 */
void timer_event_handler(nrf_timer_event_t event_type, void* p_context)
{
    switch (event_type)
    {
        case NRF_TIMER_EVENT_COMPARE1:
            send_protocol();
            break;

        default:
            //Do nothing.
            break;
    }
}


static void timer_SendData_init()
{
    uint32_t time_ms = 1000; 
    uint32_t time_ticks;
    uint32_t err_code = NRF_SUCCESS;
    
    //Configure TIMER_SEND_DATA for generating simple light effect - leds on board will invert his state one after the other.
    nrf_drv_timer_config_t timer_cfg = NRF_DRV_TIMER_DEFAULT_CONFIG;
    err_code = nrf_drv_timer_init(&TIMER_SEND_DATA, &timer_cfg, timer_event_handler);
    APP_ERROR_CHECK(err_code);

    time_ticks = nrf_drv_timer_ms_to_ticks(&TIMER_SEND_DATA, time_ms);

    nrf_drv_timer_extended_compare(
         &TIMER_SEND_DATA, NRF_TIMER_CC_CHANNEL1, time_ticks, NRF_TIMER_SHORT_COMPARE1_CLEAR_MASK, true);
}

While this first timer (nrf_drv_timer) is running,  I need a second timer whose interval I have to be able to change constantly.

E.g.

      //Do this

      time_us (10)

      //Do that

      time_us(60)

But the second timer must not influence the first. In this thread I created a timer with Håkon that uses __NOP()s. Unfortunately, these affect the first timer ...

To sum up: The second timer should be a single shot timer, whose interval I can change and which can not influence the first timer. And I know that RTC has a less resolution (~30us) but I need a resolution up to 1us. I think I can not use a timer like the first timer because of I can't changed the interval, right?

I hope, you can help me.

Thanks in advance,

Christoph

[Kenneth]

Hi,

If you want to do this properly you need an additional  timer, and start the second timer from the first timer. So I suggest to check out the nRF52840 which have 5 high frequency timers. Then you can also control the priority of the two timers, and for instance if one should be able to pre-empt the other.

Best regards,
Kenneth

[Christoph_I]

Hey Kenneth,

firstly excuse me for writing back after 9 days. I will come back later to your answer. Another issue has come up.

Best regards,

Christoph