System_off example has increased power consumption when using k_sleep iso system_off

[Ypenburg]

I run the system_off example without the system actually going off, by removing all the calls to start the system_off worker. Instead of going to off, I let the system enter sleep mode (k_sleep()).

I enabled wake up on nfc.

After a reset, the system enters sleep (4-5uA sleep current). After waking the system by nfc, the sleep current sometimes becomes 200uA, sometimes stays at 4uA. See picture below.

It seems to be related to the state of the nfc peripheral as this is the only peripheral used.

Any idea how to prevent the system going to sleep with a 200uA sleep current?

[Simonr]

Hi

Are you seeing this on an nRF54L15 DK or a custom board? If possible, can you upload the project here so we can try to reproduce this on our end?

Best regards,

Simon

[Ypenburg]

It is on an nRF54L15 DK.

/*
 * Copyright (c) 2020 Nordic Semiconductor ASA
 *
 * SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
 */

#include <stdio.h>
#include <zephyr/kernel.h>
#include <zephyr/sys/poweroff.h>
#include <zephyr/pm/device.h>

#include <nrfx.h>
#include <hal/nrf_power.h>
#if !NRF_POWER_HAS_RESETREAS
#include <hal/nrf_reset.h>
#endif

#include <nfc_t2t_lib.h>
#include <nfc/ndef/msg.h>
#include <nfc/ndef/text_rec.h>

#include <dk_buttons_and_leds.h>

#define SYSTEM_OFF_DELAY_S	3

#define MAX_REC_COUNT		1
#define NDEF_MSG_BUF_SIZE	128

#define NFC_FIELD_LED		DK_LED1
#define SYSTEM_ON_LED		DK_LED2


/* Delayed work that enters system off. */
static struct k_work_delayable system_off_work;

/**
 * @brief Function that receives events from NFC.
 */
static void nfc_callback(void *context,
			 nfc_t2t_event_t event,
			 const uint8_t *data,
			 size_t data_length)
{
	ARG_UNUSED(context);
	ARG_UNUSED(data);
	ARG_UNUSED(data_length);

	switch (event) {
	case NFC_T2T_EVENT_FIELD_ON:
		/* Cancel entering system off */
		// k_work_cancel_delayable(&system_off_work);
		dk_set_led_on(NFC_FIELD_LED);
		break;
	case NFC_T2T_EVENT_FIELD_OFF:
		/* Enter system off after delay */
		// k_work_reschedule(&system_off_work,
		// 		K_SECONDS(SYSTEM_OFF_DELAY_S));
		dk_set_led_off(NFC_FIELD_LED);
		break;
	default:
		break;
	}
}


/**
 * @brief Function for configuring and starting the NFC.
 */
static int start_nfc(void)
{
	/* Text message in its language code. */
	static const uint8_t en_payload[] = {
		'H', 'e', 'l', 'l', 'o', ' ', 'W', 'o', 'r', 'l', 'd', '!'
	};
	static const uint8_t en_code[] = {'e', 'n'};

	/* Buffer used to hold an NFC NDEF message. */
	static uint8_t buffer[NDEF_MSG_BUF_SIZE];

	NFC_NDEF_TEXT_RECORD_DESC_DEF(nfc_text_rec,
				      UTF_8,
				      en_code,
				      sizeof(en_code),
				      en_payload,
				      sizeof(en_payload));

	NFC_NDEF_MSG_DEF(nfc_text_msg, MAX_REC_COUNT);

	uint32_t len = sizeof(buffer);

	/* Set up NFC */
	if (nfc_t2t_setup(nfc_callback, NULL) < 0) {
		printk("Cannot setup NFC T2T library!\n");
		return -1;
	}

	/* Add record */
	if (nfc_ndef_msg_record_add(&NFC_NDEF_MSG(nfc_text_msg),
				&NFC_NDEF_TEXT_RECORD_DESC(nfc_text_rec)) < 0) {
		printk("Cannot add record!\n");
		return -1;
	}

	/* Encode welcome message */
	if (nfc_ndef_msg_encode(&NFC_NDEF_MSG(nfc_text_msg),
				buffer, &len) < 0) {
		printk("Cannot encode message!\n");
		return -1;
	}

	/* Set created message as the NFC payload */
	if (nfc_t2t_payload_set(buffer, len) < 0) {
		printk("Cannot set payload!\n");
		return -1;
	}

	/* Start sensing NFC field */
	if (nfc_t2t_emulation_start() < 0) {
		printk("Cannot start emulation!\n");
		return -1;
	}

	printk("NFC configuration done\n");
	return 0;
}


/**
 * @brief Function entering system off.
 * System off is delayed to make sure that NFC tag was correctly read.
 */
static void system_off(struct k_work *work)
{
	printk("Powering off.\nApproach a NFC reader to restart.\n");

	dk_set_led_off(SYSTEM_ON_LED);

	if (IS_ENABLED(CONFIG_PM_DEVICE) && IS_ENABLED(CONFIG_SERIAL)) {
		static const struct device *dev = DEVICE_DT_GET(DT_CHOSEN(zephyr_console));
		int err;
		enum pm_device_state state;

		if (dev) {
			do {
				err = pm_device_state_get(dev, &state);
			} while ((err == 0) && (state == PM_DEVICE_STATE_ACTIVE));
		}
	}

	// k_sleep(K_SECONDS(100));
	sys_poweroff();
}


/**
 * @brief  Helper function for printing the reason of the last reset.
 * Can be used to confirm that NCF field actually woke up the system.
 */
static void print_reset_reason(void)
{
	uint32_t reas;

#if NRF_POWER_HAS_RESETREAS

	reas = nrf_power_resetreas_get(NRF_POWER);
	nrf_power_resetreas_clear(NRF_POWER, reas);
	if (reas & NRF_POWER_RESETREAS_NFC_MASK) {
		printk("Wake up by NFC field detect\n");
	} else if (reas & NRF_POWER_RESETREAS_RESETPIN_MASK) {
		printk("Reset by pin-reset\n");
	} else if (reas & NRF_POWER_RESETREAS_SREQ_MASK) {
		printk("Reset by soft-reset\n");
	} else if (reas) {
		printk("Reset by a different source (0x%08X)\n", reas);
	} else {
		printk("Power-on-reset\n");
	}

#else

	reas = nrf_reset_resetreas_get(NRF_RESET);
	nrf_reset_resetreas_clear(NRF_RESET, reas);
	if (reas & NRF_RESET_RESETREAS_NFC_MASK) {
		printk("Wake up by NFC field detect\n");
	} else if (reas & NRF_RESET_RESETREAS_RESETPIN_MASK) {
		printk("Reset by pin-reset\n");
	} else if (reas & NRF_RESET_RESETREAS_SREQ_MASK) {
		printk("Reset by soft-reset\n");
	} else if (reas) {
		printk("Reset by a different source (0x%08X)\n", reas);
	} else {
		printk("Power-on-reset\n");
	}

#endif
}


int main(void)
{
	/* Configure LED-pins */
	if (dk_leds_init() < 0) {
		printk("Cannot init LEDs!\n");
		return 0;
	}
	dk_set_led_on(SYSTEM_ON_LED);

	/* Configure and start delayed work that enters system off */
	// k_work_init_delayable(&system_off_work, system_off);
	// k_work_reschedule(&system_off_work, K_SECONDS(SYSTEM_OFF_DELAY_S));

	/* Show last reset reason */
	print_reset_reason();

	/* Start NFC */
	if (start_nfc() < 0) {
		printk("ERROR: NFC configuration failed\n");
		return 0;
	}

	while (1) {
		k_sleep(K_SECONDS(5));
	}

	/* Exit main function - the rest will be done by the callbacks */
	return 0;
}

Almost identical to the system_off example. Replace the code in that example with the code above

BR,

Renger