nRF52810 will not enter deep sleep (system level power management)

[epolicar]

nRF52810 will not enter deep sleep (system level power management). The method used is through pm_policy_next_state, sleep entry function , sleep exit function, and  PM notifier. All peripherals are suspended/disabled to ensure no blocking. These are in prj.conf:

CONFIG_PM=y

CONFIG_PM_DEVICE=y

CONFIG_PM_POLICY_CUSTOM=y

CONFIG_PM_DEVICE_RUNTIME=y

CONFIG_PM_DEVICE_SYSTEM_MANAGED=y

This is the source code: 

#include <zephyr/kernel.h>

#include <zephyr/device.h>

#include <zephyr/pm/device_runtime.h>

#include <zephyr/pm/pm.h>

#include <zephyr/sys/printk.h>

#include <hal/nrf_gpio.h>

#include <hal/nrf_clock.h>

#include <cmsis_core.h>

#include <hal/nrf_power.h>

#include <hal/nrf_gpiote.h>

#include <nrfx.h>

#include <nrfx_gpiote.h>

// Replace with your actual button pin

#define WAKEUP_PIN 20  // Example: P0.20

// --- Power diagnostics ---

static void print_clock_state(void)

{

    bool hfclk = nrf_clock_hf_is_running(NRF_CLOCK, NRF_CLOCK_DOMAIN_HFCLK);

    bool lfclk = nrf_clock_lf_is_running(NRF_CLOCK);

    printk("HFCLK running: %d\n", hfclk);

    printk("LFCLK running: %d\n", lfclk);

}

static void check_pending_irqs(void)

{

    printk("Checking pending IRQs...\n");

    for (int i = 0; i < 32; i++) {

        if (NVIC_GetPendingIRQ(i)) {

            printk("IRQ %d is pending\n", i);

        }

    }

}

static void check_gpio_sense_config(void)

{

    printk("Checking GPIO sense configs...\n");

    for (int pin = 0; pin < 32; pin++) {

        nrf_gpio_pin_sense_t sense = nrf_gpio_pin_sense_get(pin);

        if (sense != NRF_GPIO_PIN_NOSENSE) {

            printk("Pin P0.%d has sense enabled (%s)\n",

                   pin,

                   sense == NRF_GPIO_PIN_SENSE_HIGH ? "HIGH" : "LOW");

        }

    }

}

const struct pm_state_info *pm_policy_next_state(uint8_t cpu, int32_t ticks)

{

    static const struct pm_state_info suspend_state = {

        .state = PM_STATE_SUSPEND_TO_RAM,

        .substate_id = 0,

        .min_residency_us = 1000,

        .exit_latency_us = 500,

    };

    printk("pm_policy_next_state() called\n");

    // Replace with your custom condition

    bool ready_to_sleep = true;

    if (ready_to_sleep) {

        return &suspend_state;

    }

    return NULL; // Stay in active state

}

void pm_state_set(enum pm_state state, uint8_t substate_id)

{

    if (state == PM_STATE_SUSPEND_TO_RAM) {

        printk("PM: Preparing to suspend...\n");

        // Configure wake-up GPIO

        nrf_gpio_cfg_input(WAKEUP_PIN, NRF_GPIO_PIN_PULLUP);

        nrf_gpio_cfg_sense_set(WAKEUP_PIN, NRF_GPIO_PIN_SENSE_LOW);

        print_clock_state();

        check_pending_irqs();

        check_gpio_sense_config();

        __SEV();

        __WFE();

        __WFE();

        printk("PM: Woke from suspend\n");

    }

}

void pm_state_exit_post_ops(enum pm_state state, uint8_t substate_id)

{

    // Optional: re-init post wake if needed

}

static void on_pm_entry(enum pm_state state)

{

    if (state == PM_STATE_SUSPEND_TO_RAM) {

        //suspend_peripherals();

        printk("Notifier: system preparing to suspend.\n");

    }

}

static void on_pm_exit(enum pm_state state)

{

    if (state == PM_STATE_SUSPEND_TO_RAM) {

        //resume_peripherals();

        printk("Notifier: system resumed from suspend.\n");

    }

}

static struct pm_notifier pm_cb = {

    .state_entry = on_pm_entry,

    .state_exit = on_pm_exit,

};

static int pm_hooks_init(void)

{

    pm_notifier_register(&pm_cb);

    return 0;

}

SYS_INIT(pm_hooks_init, POST_KERNEL, CONFIG_KERNEL_INIT_PRIORITY_DEFAULT);

void main(void)

{

    printk("System starting.\n");

    print_clock_state();

    check_pending_irqs();

    check_gpio_sense_config();

    printk("Sleeping now...\n");

    k_sleep(K_FOREVER);

   

}

I expect that after the message "Sleeping now...", I will get a message "pm_policy_next_state() called" followed by "PM: Preparing to suspend..." then "Notifier: system preparing to suspend." But the board is stuck at "Sleeping now..." Here's the RTT Viewer output:

System starting.
HFCLK running: 0
LFCLK running: 0
Checking pending IRQs...
Checking GPIO sense configs...
Sleeping now...

Does anyone have an idea on what I am doing wrong? 

I am using nRF Connect SDK v2.9.0 for VS Code, and Zephyr v3.7.99.

Thanks!

[Kazi Afroza Sultana]

Hello,

I think you need to change your power state from PM_STATE_SUSPEND_TO_RAM to PM_STATE_SOFT_OFF if you want to implement deep sleep.

The nRF52810 and other Nordic devices only support two main power modes:

System ON mode - This is the normal operating mode where the CPU can be put to sleep, but peripherals remain powered.

System OFF mode - This is the deepest power saving mode available on Nordic devices, which corresponds to PM_STATE_SOFT_OFF in Zephyr's power management states. 

You can change your code following way

a. Modifying the pm_policy_next_state() function to return PM_STATE_SOFT_OFF instead of PM_STATE_SUSPEND_TO_RAM:

const struct pm_state_info *pm_policy_next_state(uint8_t cpu, int32_t ticks)
{
    static const struct pm_state_info soft_off_state = {
        .state = PM_STATE_SOFT_OFF,
        .substate_id = 0,
        .min_residency_us = 1000,
        .exit_latency_us = 500,
    };
    printk("pm_policy_next_state() called\n");
    // Replace with your custom condition
    bool ready_to_sleep = true;
    if (ready_to_sleep) {
        return &soft_off_state;
    }

    return NULL; // Stay in active state
}

b. Updating your pm_state_set() function to handle PM_STATE_SOFT_OFF:

void pm_state_set(enum pm_state state, uint8_t substate_id)
{
    if (state == PM_STATE_SOFT_OFF) {
        printk("PM: Preparing to enter system off...\n");

        // Configure wake-up GPIO
        nrf_gpio_cfg_input(WAKEUP_PIN, NRF_GPIO_PIN_PULLUP);
        nrf_gpio_cfg_sense_set(WAKEUP_PIN, NRF_GPIO_PIN_SENSE_LOW);

        print_clock_state();
        check_pending_irqs();
        check_gpio_sense_config();

        // Enter system off mode
        printk("Entering system off mode\n");
        
        // This will put the system into deep sleep
        nrf_regulators_system_off(NRF_REGULATORS);
        
        // Code will not reach here unless system off fails
        printk("ERROR: System off failed\n");
    }
}

c. Updating your notifier callbacks to handle PM_STATE_SOFT_OFF

static void on_pm_entry(enum pm_state state)
{
    if (state == PM_STATE_SOFT_OFF) {
        //suspend_peripherals();
        printk("Notifier: system preparing to enter system off.\n");
    }
}

static void on_pm_exit(enum pm_state state)
{
    if (state == PM_STATE_SOFT_OFF) {
        //resume_peripherals();
        printk("Notifier: system resumed from system off.\n");
    }
}

Can try this and let me know if this works?

Thanks.

BR

Kazi

[epolicar]

Hi Kazi,

Thank you for your reply. PM_STATE_SOFT_OFF does work but it resets my board upon wake up. My board needs to resume upon wake up. That is why I chose PM_STATE_SUSPEND_TO_RAM. Maybe the term deep sleep is incorrect. I just need my board to consume 20uA during sleep. 

Also, as I stated in my description, all peripherals are either suspended or are disabled before sleeping.

Awaiting your reply.

Regards,

Edgar