/* USER CODE BEGIN Header */
/**
  ******************************************************************************
  * @file    Examples_LL/RCC/RCC_UseHSEasSystemClock/Src/main.c
  * @author  MCD Application Team
  * @brief   This example describes how to use the RCC LL API how to start the HSE
  *          and use it as system clock.
  ******************************************************************************
  * @attention
  *
  * Copyright (c) 2020 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.
  *
  ******************************************************************************
  */
/* USER CODE END Header */
/* Includes ------------------------------------------------------------------*/
#include "main.h"

/* Private includes ----------------------------------------------------------*/
/* USER CODE BEGIN Includes */

/* USER CODE END Includes */

/* Private typedef -----------------------------------------------------------*/
/* USER CODE BEGIN PTD */

__IO uint8_t ubReadyState = 0;
/* USER CODE END PTD */

/* Private define ------------------------------------------------------------*/
/* USER CODE BEGIN PD */

#if (USE_TIMEOUT == 1)
#define TIMEOUT_VALUE    1000 /* Time-out set to 1 sec */
#endif /* USE_TIMEOUT */

/* USER CODE END PD */

/* Private macro -------------------------------------------------------------*/
/* USER CODE BEGIN PM */

/* USER CODE END PM */

/* Private variables ---------------------------------------------------------*/

/* USER CODE BEGIN PV */

/* USER CODE END PV */

/* Private function prototypes -----------------------------------------------*/
void SystemClock_Config(void);
static void MX_GPIO_Init(void);
/* USER CODE BEGIN PFP */

void     StartHSE(void);
uint32_t RCC_WaitForHSEReady(void);
void     LED_On(void);
void     LED_Blinking(uint32_t Period);
/* USER CODE END PFP */

/* Private user code ---------------------------------------------------------*/
/* USER CODE BEGIN 0 */

/* USER CODE END 0 */

/**
  * @brief  The application entry point.
  * @retval int
  */
int main(void)
{
  /* USER CODE BEGIN 1 */

  register uint32_t frequency = 0;


  /* USER CODE END 1 */

  /* MCU Configuration--------------------------------------------------------*/

  /* Reset of all peripherals, Initializes the Flash interface and the Systick. */

  /* System interrupt init*/
  NVIC_SetPriorityGrouping(NVIC_PRIORITYGROUP_4);

  /* USER CODE BEGIN Init */

  /* USER CODE END Init */

  /* Configure the system clock */
  SystemClock_Config();

  /* USER CODE BEGIN SysInit */

  /* USER CODE END SysInit */

  /* Initialize all configured peripherals */
  MX_GPIO_Init();
  /* USER CODE BEGIN 2 */

  /* Configure Systick to 1 ms with the current frequency which should be MSI */
  frequency = __LL_RCC_CALC_MSI_FREQ(LL_RCC_MSI_IsEnabledRangeSelect(),       \
                                     (LL_RCC_MSI_IsEnabledRangeSelect() ?      \
                                      LL_RCC_MSI_GetRange() :                 \
                                      LL_RCC_MSI_GetRangeAfterStandby()));

  LL_Init1msTick(frequency);

  /* Start HSE */
  StartHSE();

  if (RCC_WaitForHSEReady() == RCC_ERROR_NONE)
  {
    /* Turn-on LED2 to indicate that HSE is ready */
    LED_On();
    ubReadyState = 1 ;
  }
  else
  {
    /* Problem to switch to HSE, blink LED2 */
    LED_Blinking(LED_BLINK_ERROR);
    ubReadyState = 0xE ;
  }

  /* USER CODE END 2 */

  /* Infinite loop */
  /* USER CODE BEGIN WHILE */
  while (1)
  {
    /* USER CODE END WHILE */

    /* USER CODE BEGIN 3 */
  }
  /* USER CODE END 3 */
}

/**
  * @brief System Clock Configuration
  * @retval None
  */
void SystemClock_Config(void)
{
  LL_FLASH_SetLatency(LL_FLASH_LATENCY_2);
  while(LL_FLASH_GetLatency() != LL_FLASH_LATENCY_2)
  {
  }

  LL_PWR_SetRegulVoltageScaling(LL_PWR_REGU_VOLTAGE_SCALE1);
  LL_RCC_MSI_Enable();

   /* Wait till MSI is ready */
  while(LL_RCC_MSI_IsReady() != 1)
  {
  }

  LL_RCC_MSI_EnableRangeSelection();
  LL_RCC_MSI_SetRange(LL_RCC_MSIRANGE_11);
  LL_RCC_MSI_SetCalibTrimming(0);
  LL_RCC_SetSysClkSource(LL_RCC_SYS_CLKSOURCE_MSI);

   /* Wait till System clock is ready */
  while(LL_RCC_GetSysClkSource() != LL_RCC_SYS_CLKSOURCE_STATUS_MSI)
  {
  }

  LL_RCC_SetAHBPrescaler(LL_RCC_SYSCLK_DIV_1);
  LL_RCC_SetAHB3Prescaler(LL_RCC_SYSCLK_DIV_1);
  LL_RCC_SetAPB1Prescaler(LL_RCC_APB1_DIV_1);
  LL_RCC_SetAPB2Prescaler(LL_RCC_APB2_DIV_1);

  LL_Init1msTick(48000000);

  /* Update CMSIS variable (which can be updated also through SystemCoreClockUpdate function) */
  LL_SetSystemCoreClock(48000000);
}

/**
  * @brief GPIO Initialization Function
  * @param None
  * @retval None
  */
static void MX_GPIO_Init(void)
{
  LL_GPIO_InitTypeDef GPIO_InitStruct = {0};

  /* GPIO Ports Clock Enable */
  LL_AHB2_GRP1_EnableClock(LL_AHB2_GRP1_PERIPH_GPIOB);

  /**/
  LL_GPIO_ResetOutputPin(LED2_GPIO_Port, LED2_Pin);

  /**/
  GPIO_InitStruct.Pin = LED2_Pin;
  GPIO_InitStruct.Mode = LL_GPIO_MODE_OUTPUT;
  GPIO_InitStruct.Speed = LL_GPIO_SPEED_FREQ_LOW;
  GPIO_InitStruct.OutputType = LL_GPIO_OUTPUT_PUSHPULL;
  GPIO_InitStruct.Pull = LL_GPIO_PULL_NO;
  LL_GPIO_Init(LED2_GPIO_Port, &GPIO_InitStruct);

}

/* USER CODE BEGIN 4 */

/**
  * Brief   This function enables the interruption HSE ready,
  *         and start the HSE as external clock.
  * @param  None
  * Retval  None
  */
void StartHSE(void)
{
  /* Configure NVIC for RCC */
  NVIC_EnableIRQ(RCC_IRQn);
  NVIC_SetPriority(RCC_IRQn, 0);

  /* Enable interrupt on HSE ready */
  /* Enable the CSS
     Enable HSE */
  /* Note : the clock is switched to HSE in the RCC_IRQHandler ISR */
  LL_RCC_EnableIT_HSERDY();
  LL_RCC_HSE_EnableCSS();
  LL_RCC_HSE_EnableTcxo();
  LL_RCC_HSE_Enable();
}

/**
  * @brief  Wait for HSE ready
  * @param  None
  * @retval RCC_ERROR_NONE if no error
  */
uint32_t RCC_WaitForHSEReady()
{
#if (USE_TIMEOUT == 1)
  /* Set timeout to 1 sec */
  uint32_t timeout = TIMEOUT_VALUE;
#endif /* USE_TIMEOUT */

  /* Check that the condition is met */
  while (LL_RCC_GetSysClkSource() != LL_RCC_SYS_CLKSOURCE_STATUS_HSE)
  {
#if (USE_TIMEOUT == 1)
    /* Check Systick counter flag to decrement the time-out value */
    if (LL_SYSTICK_IsActiveCounterFlag())
    {
      if (--timeout == 0)
      {
        /* Time-out occurred. Return an error */
        return RCC_ERROR_TIMEOUT;
      }
    }
#endif /* USE_TIMEOUT */
  }
  return RCC_ERROR_NONE;
}

/**
  * @brief  Turn-on LED2.
  * @param  None
  * @retval None
  */
void LED_On(void)
{
  /* Turn LED2 on */
  LL_GPIO_SetOutputPin(LED2_GPIO_Port, LED2_Pin);
}

/**
  * @brief  Set LED2 to Blinking mode for an infinite loop (toggle period based on value provided as input parameter).
  * @param  Period : Period of time (in ms) between each toggling of LED
  *   This parameter can be user defined values. Pre-defined values used in that example are :
  *     @arg LED_BLINK_FAST : Fast Blinking
  *     @arg LED_BLINK_SLOW : Slow Blinking
  *     @arg LED_BLINK_ERROR : Error specific Blinking
  * @retval None
  */
void LED_Blinking(uint32_t Period)
{
  /* Turn LED2 on */
  LL_GPIO_SetOutputPin(LED2_GPIO_Port, LED2_Pin);

  /* Toggle IO in an infinite loop */
  while (1)
  {
    /* Error if LED2 is slowly blinking (1 sec. period) */
    LL_GPIO_TogglePin(LED2_GPIO_Port, LED2_Pin);
    LL_mDelay(Period);
  }
}

/******************************************************************************/
/*   USER IRQ HANDLER TREATMENT                                               */
/******************************************************************************/
/**
  * @brief  This function handles the HSE ready detection (called in RCC_IRQHandler)
  * @param  None
  * @retval None
  */
void HSEReady_Callback(void)
{
  /* Switch the system clock to HSE */
  LL_RCC_SetSysClkSource(LL_RCC_SYS_CLKSOURCE_HSE);

  /* 1ms config with HSE 32MHz*/
  LL_Init1msTick(HSE_VALUE);
}

/**
  * @brief  This function handles failure detected on the HSE clock (called in NMI_Handler)
  * @param  None
  * @retval None
  */
void HSEFailureDetection_Callback(void)
{
  LED_Blinking(LED_BLINK_ERROR);
}


/* USER CODE END 4 */

/**
  * @brief  This function is executed in case of error occurrence.
  * @retval None
  */
void Error_Handler(void)
{
  /* USER CODE BEGIN Error_Handler_Debug */
  /* User can add his own implementation to report the HAL error return state */

  /* USER CODE END Error_Handler_Debug */
}

#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 CODE BEGIN 6 */
  /* 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) */
  /* USER CODE END 6 */
}
#endif /* USE_FULL_ASSERT */