RTC usage on Zephyr Issues

Hello,

I'm trying to run a simple example setting the RTC1 in a nRF52840-DK, but I'm having some issues.

Here is my prj,conf and code:

# nothing here
CONFIG_PM=y
CONFIG_PM_DEVICE=y
CONFIG_NRFX_RTC1=y

#include <zephyr/kernel.h>
#include <nrfx_rtc.h>
#include <nrfx_timer.h>

#define RTC_INSTANCE 1
#define ALARM_PERIOD_SECONDS  2
static nrfx_rtc_t rtc = NRFX_RTC_INSTANCE(RTC_INSTANCE);


void rtc_event_handler(nrfx_rtc_int_type_t int_type)
{
    if (int_type == NRFX_RTC_INT_COMPARE0) {
        // Handle RTC event here
        printk("RTC event occurred\n");
    }
}

void main(void)
{
    printk("Hello World!\n");

    nrfx_rtc_config_t config = NRFX_RTC_DEFAULT_CONFIG;
	config.prescaler = RTC_FREQ_TO_PRESCALER(1);
    nrfx_rtc_init(&rtc, &config, rtc_event_handler);
    nrfx_rtc_tick_enable(&rtc, true);
	
	uint32_t alarm_ticks = ALARM_PERIOD_SECONDS;
	nrfx_rtc_cc_set(&rtc, 0, alarm_ticks, true);
    nrfx_rtc_enable(&rtc);
}

The idea above is set the prescaler to 1 second and fire at every 2 seconds.

The RTC handler is simply not firing, as follows:

Can you help me to figure out what is missing? Code attached.

rtc_sleep.zip

Parents

0 Joao Dullius over 3 years ago

I was able to get it running with the following code:

#include <zephyr/kernel.h>
#include <zephyr/drivers/gpio.h>
#include <nrfx_rtc.h>
#include <nrfx_timer.h>

#define RTC_INSTANCE 2
#define CC_CHANNEL 0
#define RTC_TIMEOUT_MS 5000
#define RTC_PRESCALER_MS 125

static nrfx_rtc_t rtc = NRFX_RTC_INSTANCE(RTC_INSTANCE);
static const struct gpio_dt_spec led = GPIO_DT_SPEC_GET(DT_ALIAS(led1), gpios);

void rtc_event_handler(nrfx_rtc_int_type_t int_type)
{
	switch(int_type) {
		case NRFX_RTC_INT_COMPARE0:
			printk("RTC compare event occurred\n");
			gpio_pin_toggle_dt(&led);
			nrfx_rtc_counter_clear(&rtc);
        	nrfx_rtc_cc_set(&rtc, CC_CHANNEL, RTC_TIMEOUT_MS / RTC_PRESCALER_MS, true);
			break;
		default:
			break;
	}
}

void main(void)
{
    printk("Hello World!\n");

    nrfx_rtc_config_t config = NRFX_RTC_DEFAULT_CONFIG;
	config.prescaler = RTC_FREQ_TO_PRESCALER(1000 / RTC_PRESCALER_MS);
	
    nrfx_rtc_init(&rtc, &config, rtc_event_handler);

	IRQ_CONNECT(DT_IRQN(DT_NODELABEL(rtc2)),
			DT_IRQ(DT_NODELABEL(rtc2), priority),
			nrfx_isr, nrfx_rtc_2_irq_handler, 0);
	irq_enable(DT_IRQN(DT_NODELABEL(rtc2)));			

	if (!device_is_ready(led.port)) {
        return;
    }

    if (gpio_pin_configure_dt(&led, GPIO_OUTPUT_ACTIVE) < 0) {
        return;
    }

 	nrfx_rtc_tick_disable(&rtc);
    nrfx_rtc_counter_clear(&rtc);
    nrfx_rtc_enable(&rtc);
    nrfx_rtc_cc_set(&rtc, CC_CHANNEL, RTC_TIMEOUT_MS / RTC_PRESCALER_MS, true);
}

My followup question here is the following:

I'm toggling a led based on the RTC alarm.

If I set my defines as:

#define RTC_TIMEOUT_MS 5000
#define RTC_PRESCALER_MS 125

And set my prescaler and cc timer as:

config.prescaler = RTC_FREQ_TO_PRESCALER(1000 / RTC_PRESCALER_MS);

nrfx_rtc_cc_set(&rtc, CC_CHANNEL, RTC_TIMEOUT_MS / RTC_PRESCALER_MS, true);

I get the expected toggle ratio defined at RTC_TIMEOUT_MS (5 seconds).

If I change the RTC_PRESCALER_MS to a larger value, like 500 ms, I get my toogle ratio 4x faster (1.25 seconds), and not the same as I expected.

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