hello everyone

  I'm using stm32L151ccu6.  I want enter stop mode ,so I coding refer to "en.stm32cubel1"  STM32L100C-Discovery.

but it dosn't work.    can't  enter stop mode. what can i do ?

/**
  ******************************************************************************
  * @file    PWR/PWR_STOP/Src/main.c
  * @author  MCD Application Team
  * @brief   This sample code shows how to use STM32L1xx PWR HAL API to enter
  *          and exit the stop mode.
  ******************************************************************************
  * @attention
  *
  * <h2><center>&copy; COPYRIGHT(c) 2017 STMicroelectronics</center></h2>
  *
  * Redistribution and use in source and binary forms, with or without modification,
  * are permitted provided that the following conditions are met:
  *   1. Redistributions of source code must retain the above copyright notice,
  *      this list of conditions and the following disclaimer.
  *   2. Redistributions in binary form must reproduce the above copyright notice,
  *      this list of conditions and the following disclaimer in the documentation
  *      and/or other materials provided with the distribution.
  *   3. Neither the name of STMicroelectronics nor the names of its contributors
  *      may be used to endorse or promote products derived from this software
  *      without specific prior written permission.
  *
  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  *
  ******************************************************************************
  */

/* Includes ------------------------------------------------------------------*/
#include "main.h"

/** @addtogroup STM32L1xx_HAL_Examples
  * @{
  */

/** @addtogroup PWR_STOP
  * @{
  */

/* Private typedef -----------------------------------------------------------*/
typedef enum
{
  WAKE_UP_NONE = 0,
  WAKE_UP_BUTTON,
  WAKE_UP_RTC
} WakeUpSource_TypeDef;

/* Private define ------------------------------------------------------------*/
#define LED_TOGGLE_DELAY         100
/* Private macro -------------------------------------------------------------*/
/* Private variables ---------------------------------------------------------*/
/* RTC handler declaration */
RTC_HandleTypeDef RTCHandle;
static __IO uint32_t TimingDelay;
/* Variable to save last wake-up source */
__IO WakeUpSource_TypeDef WakeUpSource = WAKE_UP_NONE;

/* Private function prototypes -----------------------------------------------*/
void SystemClock_Config(void);
static void SYSCLKConfig_STOP(void);
/* Private functions ---------------------------------------------------------*/

/**
  * @brief  Main program
  * @param  None
  * @retval None
  */
int main(void)
{
  /* STM32L1xx HAL library initialization:
       - Configure the Flash prefetch
       - Systick timer is configured by default as source of time base, but user
         can eventually implement his proper time base source (a general purpose
         timer for example or other time source), keeping in mind that Time base
         duration should be kept 1ms since PPP_TIMEOUT_VALUEs are defined and
         handled in milliseconds basis.
       - Set NVIC Group Priority to 4
       - Low Level Initialization
     */
  HAL_Init();

  /* Configure LED3, and LED4 */
  BSP_LED_Init(LED3);
  BSP_LED_Init(LED4);

  /* Configure the system clock to 32 MHz */
  SystemClock_Config();

  /* User push-button (EXTI_Line0) will be used to wakeup the system from STOP mode */
  BSP_PB_Init(BUTTON_USER, BUTTON_MODE_EXTI);

  /*## Configure the RTC peripheral #######################################*/
  /* Enable Power Clock */
  __HAL_RCC_PWR_CLK_ENABLE();

  /* Allow Access to RTC Backup domaine */
  HAL_PWR_EnableBkUpAccess();

  RTCHandle.Instance = RTC;
  /* Configure RTC prescaler and RTC data registers as follows:
  - Hour Format = Format 24
  - Asynch Prediv = Value according to source clock
  - Synch Prediv = Value according to source clock
  - OutPut = Output Disable
  - OutPutPolarity = High Polarity
  - OutPutType = Open Drain */
  RTCHandle.Init.HourFormat = RTC_HOURFORMAT_24;
  RTCHandle.Init.AsynchPrediv = RTC_ASYNCH_PREDIV;
  RTCHandle.Init.SynchPrediv = RTC_SYNCH_PREDIV;
  RTCHandle.Init.OutPut = RTC_OUTPUT_DISABLE;
  RTCHandle.Init.OutPutPolarity = RTC_OUTPUT_POLARITY_HIGH;
  RTCHandle.Init.OutPutType = RTC_OUTPUT_TYPE_OPENDRAIN;
  if (HAL_RTC_Init(&RTCHandle) != HAL_OK)
  {
    /* Initialization Error */
    Error_Handler();
  }

  while (1)
  {
    /* Insert 5 second delay */
    HAL_Delay(5000);

    /*## Configure the Wake up timer ###########################################*/
    /*  RTC Wakeup Interrupt Generation:
        Wakeup Time Base = (RTC_WAKEUPCLOCK_RTCCLK_DIV /(LSI))
        Wakeup Time = Wakeup Time Base * WakeUpCounter
                    = (RTC_WAKEUPCLOCK_RTCCLK_DIV /(LSI)) * WakeUpCounter
        ==> WakeUpCounter = Wakeup Time / Wakeup Time Base
 
        To configure the wake up timer to 4s the WakeUpCounter is set to 0x242B:
          RTC_WAKEUPCLOCK_RTCCLK_DIV = RTCCLK_Div16 = 16
          Wakeup Time Base = 16 /(~37KHz) = ~0,432 ms
          Wakeup Time = ~4s = 0,432ms  * WakeUpCounter
          ==> WakeUpCounter = ~4s/0,432ms = 9259 = 0x242B */
    HAL_RTCEx_SetWakeUpTimer_IT(&RTCHandle, 0x242B, RTC_WAKEUPCLOCK_RTCCLK_DIV16);

    /* Turn OFF LED's */
    BSP_LED_Off(LED3);
    BSP_LED_Off(LED4);

    /* Enter Stop Mode */
    HAL_PWR_EnterSTOPMode(PWR_LOWPOWERREGULATOR_ON, PWR_STOPENTRY_WFI);

    /* Disable Wakeup Counter */
    HAL_RTCEx_DeactivateWakeUpTimer(&RTCHandle);

    /* Configures system clock after wake-up from STOP: enable HSE, PLL and select
    PLL as system clock source (HSE and PLL are disabled in STOP mode) */
    SYSCLKConfig_STOP();
        BSP_LED_Off(LED3);
        HAL_Delay(2000);
        BSP_LED_On(LED3);
        HAL_Delay(2000);
  }
}

/**
  * @brief  System Clock Configuration
  *         The system Clock is configured as follow :
  *            System Clock source            = PLL (HSI)
  *            SYSCLK(Hz)                     = 32000000
  *            HCLK(Hz)                       = 32000000
  *            AHB Prescaler                  = 1
  *            APB1 Prescaler                 = 1
  *            APB2 Prescaler                 = 1
  *            HSI Frequency(Hz)              = 16000000
  *            PLLMUL                         = 6
  *            PLLDIV                         = 3
  *            Flash Latency(WS)              = 1
  * @retval None
  */
void SystemClock_Config(void)
{
  RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};
  RCC_OscInitTypeDef RCC_OscInitStruct = {0};

  /* Enable HSE Oscillator and Activate PLL with HSE as source */
  RCC_OscInitStruct.OscillatorType      = RCC_OSCILLATORTYPE_HSI;
  RCC_OscInitStruct.HSIState            = RCC_HSI_ON;
  RCC_OscInitStruct.HSICalibrationValue = RCC_HSICALIBRATION_DEFAULT;
  RCC_OscInitStruct.PLL.PLLState        = RCC_PLL_ON;
  RCC_OscInitStruct.PLL.PLLSource       = RCC_PLLSOURCE_HSI;
  RCC_OscInitStruct.PLL.PLLMUL          = RCC_PLL_MUL6;
  RCC_OscInitStruct.PLL.PLLDIV          = RCC_PLL_DIV3;
  if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
  {
    Error_Handler();
  }

  /* Set Voltage scale1 as MCU will run at 32MHz */
  __HAL_RCC_PWR_CLK_ENABLE();
  __HAL_PWR_VOLTAGESCALING_CONFIG(PWR_REGULATOR_VOLTAGE_SCALE1);
 
  /* Poll VOSF bit of in PWR_CSR. Wait until it is reset to 0 */
  while (__HAL_PWR_GET_FLAG(PWR_FLAG_VOS) != RESET) {};

  /* Select PLL as system clock source and configure the HCLK, PCLK1 and PCLK2
  clocks dividers */
  RCC_ClkInitStruct.ClockType = (RCC_CLOCKTYPE_SYSCLK | RCC_CLOCKTYPE_HCLK | RCC_CLOCKTYPE_PCLK1 | RCC_CLOCKTYPE_PCLK2);
  RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
  RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
  RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV1;
  RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;
  if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_1) != HAL_OK)
  {
    Error_Handler();
  }
}
/**
  * @brief  Configures system clock after wake-up from STOP: enable HSI, PLL
  *         and select PLL as system clock source.
  * @param  None
  * @retval None
  */
static void SYSCLKConfig_STOP(void)
{
  RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};
  RCC_OscInitTypeDef RCC_OscInitStruct = {0};
  uint32_t pFLatency = 0;

  /* Enable Power Control clock */
  __HAL_RCC_PWR_CLK_ENABLE();

  /* Get the Oscillators configuration according to the internal RCC registers */
  HAL_RCC_GetOscConfig(&RCC_OscInitStruct);

  /* After wake-up from STOP reconfigure the system clock: Enable HSI and PLL */
  RCC_OscInitStruct.OscillatorType      = RCC_OSCILLATORTYPE_HSI;
  RCC_OscInitStruct.HSIState            = RCC_HSI_ON;
  RCC_OscInitStruct.HSICalibrationValue = RCC_HSICALIBRATION_DEFAULT;
  RCC_OscInitStruct.PLL.PLLState        = RCC_PLL_ON;
  if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
  {
    Error_Handler();
  }

  /* Get the Clocks configuration according to the internal RCC registers */
  HAL_RCC_GetClockConfig(&RCC_ClkInitStruct, &pFLatency);

  /* Select PLL as system clock source and configure the HCLK, PCLK1 and PCLK2
     clocks dividers */
  RCC_ClkInitStruct.ClockType     = RCC_CLOCKTYPE_SYSCLK;
  RCC_ClkInitStruct.SYSCLKSource  = RCC_SYSCLKSOURCE_PLLCLK;
  if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, pFLatency) != HAL_OK)
  {
    Error_Handler();
  }
}

/**
  * @brief  This function is executed in case of error occurrence.
  * @param  None
  * @retval None
  */
void Error_Handler(void)
{
  /* Suspend tick */
  HAL_SuspendTick();
 
  /* Turn LED3 & LED4 */
  BSP_LED_On(LED3);
  BSP_LED_On(LED4);
  while (1)
  {
  }
}

/**
  * @brief SYSTICK callback
  * @param None
  * @retval None
  */
void HAL_SYSTICK_Callback(void)
{
  HAL_IncTick();

  if (TimingDelay != 0)
  {
    TimingDelay--;
  }
  else
  {
    if (WakeUpSource == WAKE_UP_RTC)
    {
      /* Wake source was RTC, Toggle LED4 */
      BSP_LED_Toggle(LED4);
    }
    else if (WakeUpSource == WAKE_UP_BUTTON)
    {
      /* Wake source was BUTTON, Toggle LED3 */
      BSP_LED_Toggle(LED3);
    }
    else
    {
      /* No Wake source yet, Toggle LED3 */
      BSP_LED_Toggle(LED3);
    }
    TimingDelay = LED_TOGGLE_DELAY;
  }
}

/**
  * @brief  Wake Up Timer callback
  * @param  hrtc : hrtc handle
  * @retval None
  */
void HAL_RTCEx_WakeUpTimerEventCallback(RTC_HandleTypeDef *hrtc)
{
  WakeUpSource = WAKE_UP_RTC;
  /* Switch on LED3 */
  BSP_LED_On(LED3);
}

/**
  * @brief EXTI line detection callbacks
  * @param GPIO_Pin: Specifies the pins connected EXTI line
  * @retval None
  */
void HAL_GPIO_EXTI_Callback(uint16_t GPIO_Pin)
{
  if (GPIO_Pin == USER_BUTTON_PIN)
  {
    WakeUpSource = WAKE_UP_BUTTON;
    /* Switch on LED4 */
    BSP_LED_On(LED4);
  }
}

#ifdef  USE_FULL_ASSERT

/**
  * @brief  Reports the name of the source file and the source line number
  *         where the assert_param error has occurred.
  * @param  file: pointer to the source file name
  * @param  line: assert_param error line source number
  * @retval None
  */
void assert_failed(uint8_t *file, uint32_t line)
{
  /* User can add his own implementation to report the file name and line number,
     ex: printf("Wrong parameters value: file %s on line %d\r\n", file, line) */

  /* Infinite loop */
  while (1)
  {
  }
}
#endif

/**
  * @}
  */

/**
  * @}
  */

/************************ (C) COPYRIGHT STMicroelectronics *****END OF FILE****/