text: /**
    ******************************************************************************
    * @file    CRC/CRC_UserDefinedPolynomial/Src/main.c
    * @author  MCD Application Team
    * @brief   This sample code shows how to use the STM32F7xx CRC HAL API
    *          to compute a CRC code of a given buffer of data words (32-bit),
    *          based on a user-defined generating polynomial.
    ******************************************************************************
    * @attention
    *
    * Copyright (c) 2016 STMicroelectronics.
    * All rights reserved.
    *
    * This software is licensed under terms that can be found in the LICENSE file
    * in the root directory of this software component.
    * If no LICENSE file comes with this software, it is provided AS-IS.
    *
    ******************************************************************************
    */
  
  /* Includes ------------------------------------------------------------------*/
  #include "main.h"
  
  /** @addtogroup STM32F7xx_HAL_Examples
    * @{
    */
  
  /** @addtogroup CRC_UserDefinedPolynomial
    * @{
    */
  
  /* Private typedef -----------------------------------------------------------*/
  /* Private define ------------------------------------------------------------*/
  /* aDataBuffer is 32 bit long*/
  #define BUFFER_SIZE 1
  
  /* The user defined polynomial*/
  #define CRC_POLYNOMIAL_8B 0x9B /* X^8 + X^7 + X^4 + X^3 + X + 1 */
  
  /* Private macro -------------------------------------------------------------*/
  /* Private variables ---------------------------------------------------------*/
  /* CRC handler declaration */
  CRC_HandleTypeDef   CrcHandle;
  
  /* Used for storing CRC Value */
  __IO uint32_t uwCRCValue = 0;
  
  /* Buffer containing the data on which the CRC will be calculated 
    (one-word buffer in this example) */
  static const uint32_t aDataBuffer = 0x1234;
  
  /* Expected CRC Value */
  uint32_t uwExpectedCRCValue = 0xEF;
  
  /* Private function prototypes -----------------------------------------------*/
  static void MPU_Config(void);
  void SystemClock_Config(void);
  static void CPU_CACHE_Enable(void);
  static void Error_Handler(void);
  
  /* Private functions ---------------------------------------------------------*/
  
  /**
    * @brief  Main program
    * @param  None
    * @retval None
    */
  int main(void)
  {
    /* Configure the MPU attributes */
    MPU_Config();
  
    /* Enable the CPU Cache */
    CPU_CACHE_Enable();
    
    /* STM32F7xx HAL library initialization:
         - Configure the Flash ART accelerator
         - 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 216 MHz */
    SystemClock_Config();
  
    /* Configure LED5 and LED6 */
    BSP_LED_Init(LED5);
    BSP_LED_Init(LED6);  
  
    /*##-1- Configure the CRC peripheral #######################################*/
    CrcHandle.Instance = CRC;
  
    /* The default polynomial is not used. It is required to defined it in CrcHandle.Init.GeneratingPolynomial*/  
    CrcHandle.Init.DefaultPolynomialUse    = DEFAULT_POLYNOMIAL_DISABLE;
    
    /* Set the value of the polynomial */
    CrcHandle.Init.GeneratingPolynomial    = CRC_POLYNOMIAL_8B;
    
    /* The user-defined generating polynomial generates a
       8-bit long CRC */
    CrcHandle.Init.CRCLength               = CRC_POLYLENGTH_8B;
  
    /* The default init value is used */
    CrcHandle.Init.DefaultInitValueUse     = DEFAULT_INIT_VALUE_ENABLE;
  
    /* The input data are not inverted */
    CrcHandle.Init.InputDataInversionMode  = CRC_INPUTDATA_INVERSION_NONE;
  
    /* The output data are not inverted */
    CrcHandle.Init.OutputDataInversionMode = CRC_OUTPUTDATA_INVERSION_DISABLE;
  
    /* The input data are 32-bit long */
    CrcHandle.InputDataFormat              = CRC_INPUTDATA_FORMAT_WORDS;
  
    if (HAL_CRC_Init(&CrcHandle) != HAL_OK)
    {
      /* Initialization Error */
      Error_Handler();
    }
  
    /*##-2- Compute the CRC of "aDataBuffer" ###################################*/
    uwCRCValue = HAL_CRC_Calculate(&CrcHandle, (uint32_t *)&aDataBuffer, BUFFER_SIZE);
  
    /*##-3- Compare the CRC value to the Expected one ##########################*/
    if (uwCRCValue != uwExpectedCRCValue)
    {
      /* Wrong CRC value: Turn LED5 on */  
      Error_Handler();
    }
    else
    {
      /* Right CRC value: Turn LED6 on */
      BSP_LED_On(LED6);    
    }
  
    /* Infinite loop */
    while (1)
    {
    }
  }
  
  /**
    * @brief  System Clock Configuration
    *         The system Clock is configured as follow : 
    *            System Clock source            = PLL (HSE)
    *            SYSCLK(Hz)                     = 216000000
    *            HCLK(Hz)                       = 216000000
    *            AHB Prescaler                  = 1
    *            APB1 Prescaler                 = 4
    *            APB2 Prescaler                 = 2
    *            HSE Frequency(Hz)              = 25000000
    *            PLL_M                          = 25
    *            PLL_N                          = 432
    *            PLL_P                          = 2
    *            PLL_Q                          = 9
    *            VDD(V)                         = 3.3
    *            Main regulator output voltage  = Scale1 mode
    *            Flash Latency(WS)              = 7
    * @param  None
    * @retval None
    */
  void SystemClock_Config(void)
  {
    RCC_ClkInitTypeDef RCC_ClkInitStruct;
    RCC_OscInitTypeDef RCC_OscInitStruct;
    
    /* Enable HSE Oscillator and activate PLL with HSE as source */
    RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSE;
    RCC_OscInitStruct.HSEState = RCC_HSE_ON;
    RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
    RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSE;
    RCC_OscInitStruct.PLL.PLLM = 25;
    RCC_OscInitStruct.PLL.PLLN = 432;  
    RCC_OscInitStruct.PLL.PLLP = RCC_PLLP_DIV2;
    RCC_OscInitStruct.PLL.PLLQ = 9;
    if(HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
    {
      while(1) {};
    }
    
    /* Activate the OverDrive to reach the 216 Mhz Frequency */
    if(HAL_PWREx_EnableOverDrive() != HAL_OK)
    {
      while(1) {};
    }
    
    
    /* 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_DIV4;  
    RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV2;  
    if(HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_7) != HAL_OK)
    {
      while(1) {};
    }
  }
  
  
  /**
    * @brief  CPU L1-Cache enable.
    * @param  None
    * @retval None
    */
  static void CPU_CACHE_Enable(void)
  {
    /* Enable I-Cache */
    SCB_EnableICache();
  
    /* Enable D-Cache */
    SCB_EnableDCache();
  }
  
  /**
    * @brief  This function is executed in case of error occurrence.
    * @param  None
    * @retval None
    */
  static void Error_Handler(void)
  {
    while (1)
    {
      /* Error if LED5 is slowly blinking (1 sec. period) */
      BSP_LED_Toggle(LED5); 
      HAL_Delay(1000);   
    }  
  
  }
  
  
  /**
    * @brief  Configure the MPU attributes
    * @param  None
    * @retval None
    */
  static void MPU_Config(void)
  {
    MPU_Region_InitTypeDef MPU_InitStruct;
  
    /* Disable the MPU */
    HAL_MPU_Disable();
  
    /* Configure the MPU as Strongly ordered for not defined regions */
    MPU_InitStruct.Enable = MPU_REGION_ENABLE;
    MPU_InitStruct.BaseAddress = 0x00;
    MPU_InitStruct.Size = MPU_REGION_SIZE_4GB;
    MPU_InitStruct.AccessPermission = MPU_REGION_NO_ACCESS;
    MPU_InitStruct.IsBufferable = MPU_ACCESS_NOT_BUFFERABLE;
    MPU_InitStruct.IsCacheable = MPU_ACCESS_NOT_CACHEABLE;
    MPU_InitStruct.IsShareable = MPU_ACCESS_SHAREABLE;
    MPU_InitStruct.Number = MPU_REGION_NUMBER0;
    MPU_InitStruct.TypeExtField = MPU_TEX_LEVEL0;
    MPU_InitStruct.SubRegionDisable = 0x87;
    MPU_InitStruct.DisableExec = MPU_INSTRUCTION_ACCESS_DISABLE;
  
    HAL_MPU_ConfigRegion(&MPU_InitStruct);
  
    /* Enable the MPU */
    HAL_MPU_Enable(MPU_PRIVILEGED_DEFAULT);
  }
  
  #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
  
  /**
    * @}
    */
  
  /**
    * @}
    */
  
  