Using RTC to get real time for nRF9160DK

[Adeel]

Hi Dev team,

I had an issue regarding getting the real time using RTC. I tried to follow the below dev zone blog but the CAL_RTC does not work in my code.

As such, I am unable to use this to build my application. Does nR9160DK not support "CAL_RTC" like "NRF_CLOCK" .

Can you let me know how I could use the below code to build my app for nRF9160DK.

https://devzone.nordicsemi.com/f/nordic-q-a/51781/rtc-31st-date-problem-in-nrf52840

Also, a question regarding RTC and LFCLK. How can I view the real time value using RTC and LFCLK.

I can see in the debugger that they are running but I need to know the real time through it. Some help in explaining this would be appreciated :).

Regards,

Adeel.

[ovrebekk]

Hi Adeel

How does this case relate to the other one you opened recently?
https://devzone.nordicsemi.com/f/nordic-q-a/64931/using-rtc-to-control-the-real-timestamp

For simplicity I will handle both. 

CAL_RTC is simply a define in nrf_calendar.h, and is defined to NRF_RTC0 by default. 

Please be aware that this example is not developed for NCS/Zephyr, so I am not sure how well it works there. Ideally it would have to be modified to use the nrfx drivers, which are supported both in the nRF5 SDK and in NCS. 

Best regards
Torbjørn

[Adeel]

Hi Tobjorn,

I am basically stuck in an issue wherein I need to get the real time and schedule certain events at that time.

The idea here was to use LFCLK and RTC to try and obtain the real time and schedule events and interrupts based on that.

For that, I needed an idea in order to get and schedules events and interrupts through RTC and LFCLK.

Regards,

Adeel.

[ovrebekk]

Hi Adeel

It is not supported in Zephyr, no. 

I am guessing all the examples you found using NVIC are based on the nRF5 SDK, not on Zephyr.

For nRF52 development the nRF5 SDK is a good option, and you can use that if you want, but for the nRF53 series, nRF91 series and future chip series we will not support the nRF5 SDK. 

Best regards
Torbjørn

[Adeel]

Hi Tobjorn,

Thanks for the help. This clears up the doubts I had regarding the interrupts :).

Regards,

Adeel.

[ovrebekk]

Great Adeel, I am happy to help

[Adeel]

Hi Tobjorn,

One basic question regarding the same observation:

NRF_RTC0->EVENTS_COMPARE[0] = 0;

NRF_RTC0->CC[0] = NRF_RTC0->COUNTER + 1000;

 Do these commands also not work with the nRF91 series ? I am trying to use them but I see no effect. 

[Adeel]

Hi Tobjorn,

Continuing my previous question, I had an issue regarding setting the RTC compare value for periodic compare events. 

https://github.com/Rallare/fw-nrfconnect-nrf/tree/nrf9160_samples/samples/nrf9160/nrfx/rtc

I used the following example and was building on it. Its working fine for 1 compare event but I wish to have periodic compare events at my scheduled times.

To do that, I am trying to update the compare value by adding it to the counter value in the rtc_handler() part of the code as soon as I get my 1st compare event.

The ideas was this: NEW_COMPARE_VALUE = CURRENT_COUNTER_VALUE + PREVIOUS_COMPARE_VALUE;

For some reason, the compare value does not update and I don't get the next compare event. Could you help me with the code structure that updates the compare value of the counter for periodic events.

Regards,

Adeel.

[ovrebekk]

Hi Adeel

I updated the Rallare RTC example to update the CC register as you describe, and it seems to work fine for me. 

The only change I did was to update the rtc_handler function like this:

static void rtc_handler(nrfx_rtc_int_type_t int_type)
{
	int rtc_value;
	if (int_type == NRFX_RTC_INT_COMPARE0) {
		nrf_gpio_pin_toggle(LED_0);

		// Get the current counter value, add COMPARE_COUNTERTIME * 8, and update the CC 0 register
		rtc_value = nrfx_rtc_counter_get(&rtc);
		rtc_value += COMPARE_COUNTERTIME * 8;
		nrfx_rtc_cc_set(&rtc, 0, rtc_value, true);

	} else if (int_type == NRFX_RTC_INT_TICK) {
		nrf_gpio_pin_toggle(LED_1);
	}
}

Flashing the code I can see LED1 on the DK (referred to as LED_0 in the code) blink every few seconds. 

Best regards
Torbjørn

[Adeel]

Hi Tobjorn,

Yes, This works. I forgot about the nrfx_rtc_counter_get() function in order to get the counter value . 

Thanks for helping me out here :).

Regards,

Adeel.

[ovrebekk]

Hi Adeel

I'm happy to help, good to hear you got it working

Best regards
Torbjørn