text: /**
    ******************************************************************************
    * @file    WWDG/WWDG_Example/Src/main.c
    * @author  MCD Application Team
    * @version V1.5.0
    * @date    14-April-2017
    * @brief   This sample code shows how to use the STM32F103xB WWDG HAL API
    *          to update at regular period the WWDG counter and how to simulate
    *          a software fault generating an MCU WWDG reset on expiry of a
    *          programmed time period.
    ******************************************************************************
    * @attention
    *
    * <h2><center>&copy; COPYRIGHT(c) 2016 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 STM32F1xx_HAL_Examples
    * @{
    */
  
  /** @addtogroup WWDG_Example
    * @{
    */
  
  /* Private typedef -----------------------------------------------------------*/
  /* Private define ------------------------------------------------------------*/
  /* Private macro -------------------------------------------------------------*/
  /* Private variables ---------------------------------------------------------*/
  /* WWDG handler declaration */
  static WWDG_HandleTypeDef   WwdgHandle;
  
  /* Private function prototypes -----------------------------------------------*/
  static uint32_t TimeoutCalculation(uint32_t timevalue);
  void SystemClock_Config(void);
  static void Error_Handler(void);
  
  /* Private functions ---------------------------------------------------------*/
  
  /**
    * @brief  Main program
    * @param  None
    * @retval None
    */
  int main(void)
  {
    uint32_t delay;
      
    /* STM32F103xB 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 the system clock to 64 MHz */
    SystemClock_Config();
    
    /* Configure LED2 */
    BSP_LED_Init(LED2);
  
    /* Configure User push-button */
    BSP_PB_Init(BUTTON_USER, BUTTON_MODE_EXTI);
  
    /*##-1- Check if the system has resumed from WWDG reset ####################*/
    if (__HAL_RCC_GET_FLAG(RCC_FLAG_WWDGRST) != RESET)
    {
      /* WWDGRST flag set: Turn LED2 on */
      BSP_LED_On(LED2);
  
      /* Insert 4s delay */
      HAL_Delay(4000);
  
      /* Clear reset flags */
      __HAL_RCC_CLEAR_RESET_FLAGS();
    }
    else
    {
      /* WWDGRST flag is not set: Turn LED2 off */
      BSP_LED_Off(LED2);
    }
  
    /*##-2- Configure the WWDG peripheral ######################################*/
    /* WWDG clock counter = (PCLK1 (32MHz)/4096)/8) = 976.56 Hz (~1024 us) 
       WWDG Window value = 80 means that the WWDG counter should be refreshed only 
       when the counter is below 80 (and greater than 64/0x40) otherwise a reset will 
       be generated. 
       WWDG Counter value = 127, WWDG timeout = ~1024 us * 64 = 65 ms */
    WwdgHandle.Instance = WWDG;
  
    WwdgHandle.Init.Prescaler = WWDG_PRESCALER_8;
    WwdgHandle.Init.Window    = 80U;
    WwdgHandle.Init.Counter   = 127U;
  
    if (HAL_WWDG_Init(&WwdgHandle) != HAL_OK)
    {
      /* Initialization Error */
      Error_Handler();
    }
    
    /* calculate delay to enter window. Add 1ms to secure round number to upper number  
       Time to enter inside window
        Window timeout (in ms) = (127 - 80 + 1) * 1.024 = 49.152 ms */
    delay = TimeoutCalculation((WwdgHandle.Init.Counter - WwdgHandle.Init.Window) + 1) + 1;
    
    /* Infinite loop */
    while (1)
    {
      /* Toggle LED2 */
      BSP_LED_Toggle(LED2);
  
      /* Insert calculated delay */
      HAL_Delay(delay);
  
      /* Refresh WWDG */
      if (HAL_WWDG_Refresh(&WwdgHandle) != HAL_OK)
      {
        Error_Handler();
      }
    }
  }
  
  /**
    * @brief  Timeout calculation function.
    *         This function calculates any timeout related to 
    *         WWDG with given prescaler and system clock.
    * @param  timevalue: period in term of WWDG counter cycle.
    * @retval None
    */
  static uint32_t TimeoutCalculation(uint32_t timevalue)
  {
    uint32_t timeoutvalue = 0;
    uint32_t pclk1 = 0;
    uint32_t wdgtb = 0;
  
    /* considering APB divider is still 1, use HCLK value */
    pclk1 = HAL_RCC_GetPCLK1Freq();
  
    /* get prescaler */
    wdgtb = (1 << ((WwdgHandle.Init.Prescaler) >> 7)); /* 2^WDGTB[1:0] */
  
    /* calculate timeout */
    timeoutvalue = ((4096 * wdgtb * timevalue) / (pclk1 / 1000));
  
    return timeoutvalue;
  }
  
  /**
    * @brief  System Clock Configuration
    *         The system Clock is configured as follow : 
    *            System Clock source            = PLL (HSI)
    *            SYSCLK(Hz)                     = 64000000
    *            HCLK(Hz)                       = 64000000
    *            AHB Prescaler                  = 1
    *            APB1 Prescaler                 = 2
    *            APB2 Prescaler                 = 1
    *            PLLMUL                         = 16
    *            Flash Latency(WS)              = 2
    * @param  None
    * @retval None
    */
  void SystemClock_Config(void)
  {
    RCC_ClkInitTypeDef clkinitstruct = {0};
    RCC_OscInitTypeDef oscinitstruct = {0};
    
    /* Configure PLL ------------------------------------------------------*/
    /* PLL configuration: PLLCLK = (HSI / 2) * PLLMUL = (8 / 2) * 16 = 64 MHz */
    /* PREDIV1 configuration: PREDIV1CLK = PLLCLK / HSEPredivValue = 64 / 1 = 64 MHz */
    /* Enable HSI and activate PLL with HSi_DIV2 as source */
    oscinitstruct.OscillatorType  = RCC_OSCILLATORTYPE_HSI;
    oscinitstruct.HSEState        = RCC_HSE_OFF;
    oscinitstruct.LSEState        = RCC_LSE_OFF;
    oscinitstruct.HSIState        = RCC_HSI_ON;
    oscinitstruct.HSICalibrationValue = RCC_HSICALIBRATION_DEFAULT;
    oscinitstruct.HSEPredivValue    = RCC_HSE_PREDIV_DIV1;
    oscinitstruct.PLL.PLLState    = RCC_PLL_ON;
    oscinitstruct.PLL.PLLSource   = RCC_PLLSOURCE_HSI_DIV2;
    oscinitstruct.PLL.PLLMUL      = RCC_PLL_MUL16;
    if (HAL_RCC_OscConfig(&oscinitstruct)!= HAL_OK)
    {
      /* Initialization Error */
      while(1); 
    }
  
    /* Select PLL as system clock source and configure the HCLK, PCLK1 and PCLK2 
       clocks dividers */
    clkinitstruct.ClockType = (RCC_CLOCKTYPE_SYSCLK | RCC_CLOCKTYPE_HCLK | RCC_CLOCKTYPE_PCLK1 | RCC_CLOCKTYPE_PCLK2);
    clkinitstruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
    clkinitstruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
    clkinitstruct.APB2CLKDivider = RCC_HCLK_DIV1;
    clkinitstruct.APB1CLKDivider = RCC_HCLK_DIV2;  
    if (HAL_RCC_ClockConfig(&clkinitstruct, FLASH_LATENCY_2)!= HAL_OK)
    {
      /* Initialization Error */
      while(1); 
    }
  }
  
  /**
    * @brief  This function is executed in case of error occurrence.
    * @param  None
    * @retval None
    */
  static void Error_Handler(void)
  {
    /* Turn LED2 off */
    BSP_LED_Off(LED2);
  
    while(1)
    {
    }
  }
  
  #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****/
  