nrf54l15: RTC causing increase in sleep current

RE: nrf54l15: RTC causing increase in sleep current

Jørgen Holmefjord — Tue, 01 Apr 2025 11:26:59 GMT

Hi,

Attaching a minimal sample where I used a k_timer to wakeup every 1000ms to toggle a LED: devzone.nordicsemi.com/.../k_5F00_timer_5F00_sample_5F00_ncs290.zip

Measured average current consumption over 60 seconds on nRF54L15 DK is about 5.4uA (VDD=3.0V) or 5.7uA (VDD=1.8V):

Best regards,
Jørgen

RE: nrf54l15: RTC causing increase in sleep current

payalD — Mon, 31 Mar 2025 06:10:22 GMT

Hello,

Any updates on the above query?

RE: nrf54l15: RTC causing increase in sleep current

payalD — Fri, 28 Mar 2025 08:44:00 GMT

Hello,

[quote userid="14926" url="~/f/nordic-q-a/120231/nrf54l15-rtc-causing-increase-in-sleep-current/529322"]You can use the Timer API to configure periodical wakeup[/quote]

I tried the Timer API to configure periodic wakeups. The wake-up functionality works as expected, but the sleep current has increased to 8 - 10 micro Amps. Following is the code snipped I have used to configure the periodic wake-up timer.

#define WAKEUP_INTERVAL_MS          120000

uint8_t timer_wakeup;

void init_wakeup_timer(void)
{
    k_timer_start(&wakeup_timer, K_NO_WAIT, K_MSEC(WAKEUP_INTERVAL_MS));
    k_timer_status_sync(&wakeup_timer);
}

void wakeup_handler(struct k_timer * timer)
{
    timer_wakeup = 1;
}

uint8_t get_timer_wakeup_flag(void)
{
    return timer_wakeup;
}

void set_timer_wakeup_flag(uint8_t val)
{
    timer_wakeup = val;
}

I continuously check the value of timer_wakeup; if it is 1, action is taken to wake-up the device from sleep mode.

void execute_sleep_app(void)
{
    if(sleep_flag)
    {
		pm_device_action_run(UART0, PM_DEVICE_ACTION_SUSPEND);
		pm_device_action_run(UART1, PM_DEVICE_ACTION_SUSPEND);

        while(1)
        {
            k_sleep(K_SECONDS(5));
            if(get_timer_wakeup_flag() == 1)
            {
                break;
            }
        }

        if(get_timer_wakeup_flag())
        {
			pm_device_action_run(UART0, PM_DEVICE_ACTION_RESUME);
			pm_device_action_run(UART1, PM_DEVICE_ACTION_RESUME);
            set_timer_wakeup_flag(0);
            set_sleep_flag(0);
            notify_wakeup(APP_METER);
        }
    }
}

What changes should I make to reduce the sleep current?

I tried to stop the timer using k_timer_stop(&wakeup_timer); before putting the device in sleep mode, it reduced the sleep current to 4 micro Amps, but the device did not wake up once put in sleep mode.

Thanks,

Payal

RE: nrf54l15: RTC causing increase in sleep current

Jørgen Holmefjord — Thu, 27 Mar 2025 14:01:32 GMT

Hi,

The GRTC is already used as the kernel timer in Zephyr and will be always running to handle scheduling. You can use the Timer API to configure periodical wakeup. The timer API is very simple and explained well in the examples in the documentation.

Best regards,
Jørgen