/*
 * Copyright (c) 2006-2021, RT-Thread Development Team
 *
 * SPDX-License-Identifier: Apache-2.0
 *
 * Change Logs:
 * Date           Author       Notes
 * 2019-05-09     Zero-Free    first implementation
 */

#include <board.h>
#include <rtthread.h>
#include <rtdevice.h>

#ifdef RT_USING_PM

#define WAKEUP_EVENT_BUTTON                 (1 << 0)
#define PIN_LED_R                           GET_PIN(E, 7)
#define WAKEUP_PIN                          GET_PIN(C, 13)
#define WAKEUP_APP_THREAD_STACK_SIZE        1024

static rt_event_t wakeup_event;

static void wakeup_callback(void *args)
{
    rt_event_send(wakeup_event, WAKEUP_EVENT_BUTTON);
}

static void wakeup_init(void)
{
    rt_pin_mode(WAKEUP_PIN, PIN_MODE_INPUT_PULLUP);
    rt_pin_attach_irq(WAKEUP_PIN, PIN_IRQ_MODE_FALLING, wakeup_callback, RT_NULL);
    rt_pin_irq_enable(WAKEUP_PIN, 1);
}

static void wakeup_app_entry(void *parameter)
{
    wakeup_init();

while (1)
    {
        if (rt_event_recv(wakeup_event,
                          WAKEUP_EVENT_BUTTON,
                          RT_EVENT_FLAG_AND | RT_EVENT_FLAG_CLEAR,
                          RT_WAITING_FOREVER, RT_NULL) == RT_EOK)
        {
            rt_pm_request(PM_SLEEP_MODE_NONE);

rt_pin_mode(PIN_LED_R, PIN_MODE_OUTPUT);
            rt_pin_write(PIN_LED_R, 0);
            rt_thread_delay(rt_tick_from_millisecond(500));
            rt_pin_write(PIN_LED_R, 1);

rt_pm_release(PM_SLEEP_MODE_NONE);
        }
    }
}

static int wakeup_app(void)
{
    rt_thread_t tid;

wakeup_event = rt_event_create("wakup", RT_IPC_FLAG_PRIO);
    RT_ASSERT(wakeup_event != RT_NULL);

tid = rt_thread_create("wakeup_app", wakeup_app_entry, RT_NULL,
                           WAKEUP_APP_THREAD_STACK_SIZE, RT_MAIN_THREAD_PRIORITY, 20);
    RT_ASSERT(tid != RT_NULL);

rt_thread_startup(tid);

return 0;
}
INIT_APP_EXPORT(wakeup_app);

#endif
现在创建了一个wakeup_app的线程，通过终端发送Pm_release进入睡眠，等待按键事件按下，然后唤醒。待进入睡眠后，按下按键，可以看到wakeup_app线程里的指示灯点亮，但没有熄灭，程序未死机，还一直在运行。
static void sleep(struct rt_pm *pm, uint8_t mode)
{
    switch (mode)
    {
    case PM_SLEEP_MODE_NONE:
        break;

case PM_SLEEP_MODE_IDLE:
        // __WFI();
        break;

case PM_SLEEP_MODE_LIGHT:
        if (pm->run_mode == PM_RUN_MODE_LOW_SPEED)
        {
            /* Enter LP SLEEP Mode, Enable low-power regulator */
            HAL_PWR_EnterSLEEPMode(PWR_LOWPOWERREGULATOR_ON, PWR_SLEEPENTRY_WFI);
        }
        else
        {
            /* Enter SLEEP Mode, Main regulator is ON */
            HAL_PWR_EnterSLEEPMode(PWR_MAINREGULATOR_ON, PWR_SLEEPENTRY_WFI);
        }
        break;

case PM_SLEEP_MODE_DEEP:
        /* Enter STOP 2 mode  */
        SysTick->CTRL &= ~SysTick_CTRL_ENABLE_Msk;
        HAL_PWREx_EnterSTOP2Mode(PWR_STOPENTRY_WFI);
        /* Re-configure the system clock */
        SysTick->CTRL =| SysTick_CTRL_ENABLE_Msk;
        SystemClock_ReConfig(pm->run_mode);
        break;

case PM_SLEEP_MODE_STANDBY:
        /* Enter STANDBY mode */
        HAL_PWR_EnterSTANDBYMode();
        break;

case PM_SLEEP_MODE_SHUTDOWN:
        /* Enter SHUTDOWNN mode */
        HAL_PWREx_EnterSHUTDOWNMode();
        break;

default:
        RT_ASSERT(0);
        break;
    }
}
在进入深睡眠前关闭systick，唤醒后开启systick.