Triggering saadc with RTC2 compare channel - initially working and than stops

RE: Triggering saadc with RTC2 compare channel - initially working and than stops

Ron — Wed, 22 Sep 2021 10:03:31 GMT

Hi Vidar,

I wrongly assumed that resetting the CC (By nrf_drv_rtc_cc_set) will be enough and no writing to the CC itself directly will not be required. anyway that fixed it,

Thanks!

RE: Triggering saadc with RTC2 compare channel - initially working and than stops

Vidar Berg — Thu, 16 Sep 2021 14:07:02 GMT

Hi,

You also need to clear the counter from your adc_rtc2_start_sequence() function. Depending on your RTC configuration, It can take quite a while for the counter register to wrap over.

RE: Triggering saadc with RTC2 compare channel - initially working and than stops

Ron — Thu, 16 Sep 2021 14:04:00 GMT

Hey,

That is the handler,

I am calling it exactly the same from a different place as well, a timer handler which is called cyclically

void adc_rtc2_start_sequence(void)
{
	err_code = nrf_drv_rtc_cc_set(&rtc,0,COMPARE_COUNTERTIME * 200,true);
	APP_ERROR_CHECK(err_code);
}

static void meas_timeout_handler(void * p_context)
{
    adc_rtc2_start_sequence();
}

//---------------
#define BATTERY_MEAS_INTERVAL_FIRST     	APP_TIMER_TICKS((1000)) 
APP_TIMER_DEF(m_battery_timer_id);
//---------------
app_timer_create(&m_battery_timer_id, APP_TIMER_MODE_REPEATED, meas_timeout_handler);
app_timer_start(m_battery_timer_id, BATTERY_MEAS_INTERVAL_FIRST, NULL);

RE: Triggering saadc with RTC2 compare channel - initially working and than stops

Vidar Berg — Thu, 16 Sep 2021 13:57:07 GMT

Hi,

I only see you calling nrf_drv_rtc_cc_set(&rtc,0,COMPARE_COUNTERTIME * 200,true); when you hit the else statement in rtc_handler() and not if you enter the first if statement.

RE: Triggering saadc with RTC2 compare channel - initially working and than stops

Ron — Thu, 16 Sep 2021 13:48:07 GMT

Hi,

[quote userid="4240" url="~/f/nordic-q-a/79693/triggering-saadc-with-rtc2-compare-channel---initially-working-and-than-stops/329862#329862"]Can you set the CC register to trigger the interrupt again in 1 second [/quote]

Yes, after 1 sec I do call the same command again; I call it cyclically every 1 sec,

err_code = nrf_drv_rtc_cc_set(&rtc,0,COMPARE_COUNTERTIME * 200,true);

But the interrupt does not appear again as in the first call, and I don't know why

Thanks

RE: Triggering saadc with RTC2 compare channel - initially working and than stops

Vidar Berg — Thu, 16 Sep 2021 13:28:49 GMT

Hi,

[quote userid="67544" url="~/f/nordic-q-a/79693/triggering-saadc-with-rtc2-compare-channel---initially-working-and-than-stops/329860#329860"]regrading the retriggering, what if I want it to stop after 4 samples for example, and than start the cycle again in the future, say after 1 sec?[/quote]

Can you set the CC register to trigger the interrupt again in 1 second then?

RE: Triggering saadc with RTC2 compare channel - initially working and than stops

Ron — Thu, 16 Sep 2021 13:27:17 GMT

Hi,

I understand regarding the rest,

regrading the retriggering, what if I want it to stop after 4 samples for example, and than start the cycle again in the future, say after 1 sec?

Thanks again

RE: Triggering saadc with RTC2 compare channel - initially working and than stops

Vidar Berg — Thu, 16 Sep 2021 12:57:06 GMT

Hi,

[quote userid="67544" url="~/f/nordic-q-a/79693/triggering-saadc-with-rtc2-compare-channel---initially-working-and-than-stops/329845#329845"]If I clear it, do I still need to do the following? :[/quote]

The driver is responsible for clearing of these events. So no, you shouldn't clear them in the application callback.

You have to explicitly re-enable the event by calling nrf_drv_rtc_cc_set() after you have gotten a compare event if you want the compare event to trigger again. This is because the driver's IRQ handler is disables it.

RE: Triggering saadc with RTC2 compare channel - initially working and than stops

Ron — Thu, 16 Sep 2021 12:42:46 GMT

Hi Vidar,

Thanks for your help,

If I clear it, do I still need to do the following? :

	NRF_RTC2->EVENTS_COMPARE[0] = 0;
	NRF_RTC2->EVENTS_COMPARE[1] = 0;
	NRF_RTC2->EVENTS_COMPARE[2] = 0;
	NRF_RTC2->EVENTS_COMPARE[3] = 0;
    NRF_RTC2->EVENTS_TICK       = 0;
    NRF_RTC2->EVENTS_OVRFLW     = 0;

Anyway I implemented the following code

static void rtc_handler(nrf_drv_rtc_int_type_t int_type)
{
    ret_code_t err_code;
		
		if (int_type == NRF_DRV_RTC_INT_COMPARE0)
		{
			nrf_drv_rtc_counter_clear(&rtc);
				
			//-------------------------------------
			if (rtc2_c0_counter >= ADC_BUFFER_SIZE)
			{
				rtc2_c0_counter = 0;
			}			
			else
			{
				err_code = nrf_drv_rtc_cc_set(&rtc,0,COMPARE_COUNTERTIME * 200,true);
				rtc2_c0_counter++;
			}		
		}
}

It still does not work beyond the first series of samples, as long as I am resetting the the CC -

nrf_drv_rtc_cc_set(&rtc,0,COMPARE_COUNTERTIME * 200,true);

it is working, but after I stop it on the ADC_BUFFER_SIZE sample, it never starts again, clearing the RTC does not seems to fix it.

Any ideas?

Thanks!

RE: Triggering saadc with RTC2 compare channel - initially working and than stops

Vidar Berg — Thu, 16 Sep 2021 12:06:55 GMT

Hello,

Looks like you are forgetting to clear the RTC counter from the driver callback?

Please try to clear it like this:

static void rtc_handler(nrf_drv_rtc_int_type_t int_type)
{
    uint32_t err_code; 

    if (int_type == NRF_DRV_RTC_INT_COMPARE0)
    {
        nrf_gpio_pin_toggle(COMPARE_EVENT_OUTPUT);
        
        nrf_drv_rtc_counter_clear(&rtc);
        err_code = nrf_drv_rtc_cc_set(&rtc,0 ,COMPARE_COUNTERTIME * 200,true);
        APP_ERROR_CHECK(err_code);
    }
}

Best regards,

Vidar