• RCC初始化学习

    一、设置RCC时钟

    1. //#define SYSCLK_HSE
    2. #define SYSCLK_FREQ_20MHz
    3. //#define SYSCLK_FREQ_36MHz
    4. //#define SYSCLK_FREQ_48MHz
    5. //#define SYSCLK_FREQ_72MHz

    7. /*******************************************************************************
    8. * Function Name : SetSysClock
    9. * Description : Configures the System clock frequency, HCLK, PCLK2 and PCLK1 prescalers.
    10. * Input : None
    11. * Output : None
    12. * Return : None
    13. *******************************************************************************/
    14. void SetSysClock(void)
    15. {
    16. #if defined SYSCLK_HSE
    17.         SetSysClockToHSE();
    18. #elif defined SYSCLK_FREQ_20MHz
    19.         SetSysClockTo20();
    20. #elif defined SYSCLK_FREQ_36MHz
    21.         SetSysClockTo36();
    22. #elif defined SYSCLK_FREQ_48MHz
    23.         SetSysClockTo48();
    24. #elif defined SYSCLK_FREQ_72MHz
    25.         SetSysClockTo72();
    26. #endif
    27. }
    SetSysClockToHSE：
    1. ErrorStatus HSEStartUpStatus;
    2. /*******************************************************************************
    3. * Function Name : SetSysClockToHSE
    4. * Description : Selects HSE as System clock source and configure HCLK,PCLK2 and PCLK1 prescalers.
    5. * Input : None
    6. * Output : None
    7. * Return : None
    8. *******************************************************************************/
    9. void SetSysClockToHSE(void)
    10. {
    11.     /* Deinitialize the RCC registers */
    12.     RCC_DeInit();
    13.     /* Enable the HSE */
    14.     RCC_HSEConfig(RCC_HSE_ON);
    15.     /* Wait till HSE is ready and if Time out is reached exit */
    16.     HSEStartUpStatus = RCC_WaitForHSEStartUp();
    17.     if(HSEStartUpStatus == SUCCESS)
    18.     {
    19.         /* Add here PLL ans system clock config */
    20.         
    21.         /* Enable The Prefetch Buffer */
    22.         FLASH_PrefetchBufferCmd(FLASH_PrefetchBuffer_Enable);
    23.         
    24.         /* Configure Tthe Latency cycle: Set 0 Latency cycles */
    25.         FLASH_SetLatency(FLASH_Latency_0);
    26.         
    27.         /* Configure HCLK such as HCLK = SYSCLK */
    28.         RCC_HCLKConfig(RCC_SYSCLK_Div1);
    29.         
    30.         /* PCLK2 = HCLK*/
    31.         RCC_PCLK2Config(RCC_HCLK_Div1);
    32.         
    33.         /* PCLK1 = HCLK*/
    34.         RCC_PCLK1Config(RCC_HCLK_Div1);
    35.         
    36.         /* Select HSE as system clock source*/
    37.         RCC_SYSCLKConfig(RCC_SYSCLKSource_HSE);
    38.         
    39.         /* Wait till HSE is used as system clock source */
    40.         if(RCC_GetSYSCLKSource() != 0x04)
    41.         {
    42.             
    43.         }
    44.         else
    45.         {
    46.             
    47.         }
    48.     }
    49.     else
    50.     {
    51.         /* If HSE fails to start-up. */
    52.         while(1)
    53.         {
    54.         }
    55.     }
    56. }
    SetSysClockTo20：
    1. /*******************************************************************************
    2. * Function Name : SetSysClockTo20
    3. * Description : Sets System clock frequency to 20MHz and configure HCLK, PCLK2 and PCLK1 prescalers.
    4. * Input : None
    5. * Output : None
    6. * Return : None
    7. *******************************************************************************/
    8. void SetSysClockTo20(void)
    9. {
    10.     /* SYSCLK, HCLK, PCLK2 and PCLK1 configuration -----------------------------*/
    11.     /* RCC system reset(for debug purpose) */
    12.     RCC_DeInit();    
    13.     
    14.     /* Enable HSE */
    15.     RCC_HSEConfig(RCC_HSE_ON);
    16.     
    17.     /* Wait till HSE is ready */
    18.     HSEStartUpStatus = RCC_WaitForHSEStartUp();
    19.     if(HSEStartUpStatus == SUCCESS)
    20.     {
    21.      /* Enable Prefetch Buffer */
    22.         FLASH_PrefetchBufferCmd(FLASH_PrefetchBuffer_Enable);
    23.         
    24.         /* Flash 0 wait state */
    25.         FLASH_SetLatency(FLASH_Latency_0);
    26.         
    27.      /* HCLK = SYSCLK */
    28.         RCC_HCLKConfig(RCC_SYSCLK_Div1);
    29.         
    30.      /* PCLK2 = HCLK */
    31.         RCC_PCLK2Config(RCC_HCLK_Div1);
    32.         
    33.      /* PCLK1 = HCLK */
    34.         RCC_PCLK1Config(RCC_HCLK_Div1);
    35.         
    36.      /* PLLCLK = (8MHz / 2) * 5 = 20 MHz */
    37.         RCC_PLLConfig(RCC_PLLSource_HSE_Div2, RCC_PLLMul_5);
    38.         
    39.         /* Enable PLL */
    40.         RCC_PLLCmd(ENABLE);
    41.         
    42.      /* Wait till PLL is ready */
    43.         while(RCC_GetFlagStatus(RCC_FLAG_PLLRDY) == RESET)
    44.         {
    45.             
    46.         }
    47.         
    48.      /* Select PLL as system clock source */
    49.         RCC_SYSCLKConfig(RCC_SYSCLKSource_PLLCLK);
    50.         
    51.      /* Wait till PLL is used as system clock source */
    52.         if(RCC_GetSYSCLKSource() != 0x80)
    53.         {
    54.         }
    55.         else
    56.         {
    57.         }
    58.     }
    59.     else
    60.     {
    61.         /* If HSE fails to start-up. */
    62.         while(1)
    63.         {
    64.         }
    65.     }
    SetSysClockTo36：
    1. /*******************************************************************************
    2. * Function Name : SetSysClockTo36
    3. * Description : Sets System clock frequency to 36MHz and configure HCLK, PCLK2 and PCLK1 prescalers.
    4. * Input : None
    5. * Output : None
    6. * Return : None
    7. *******************************************************************************/
    8. void SetSysClockTo36(void)
    9. {
    10.     /* RCC system reset */
    11.     RCC_DeInit();
    12.     /* Enable HSE */
    13.     RCC_HSEConfig(RCC_HSE_ON);
    14.     
    15.     /* Wait till HSE is ready */
    16.     HSEStartUpStatus = RCC_WaitForHSEStartUp();
    17.     if(HSEStartUpStatus == SUCCESS)
    18.     {
    19.         /* Enable Prefetch Buffer*/
    20.         FLASH_PrefetchBufferCmd(FLASH_PrefetchBuffer_Enable);
    21.         
    22.         /* Flash 1 wait state */
    23.         FLASH_SetLatency(FLASH_Latency_1);
    24.         
    25.         /* HCLK = SYSCLK */
    26.         RCC_HCLKConfig(RCC_SYSCLK_Div1);
    27.         
    28.         /* PCLK2 = HCLK */
    29.         RCC_PCLK2Config(RCC_HCLK_Div1);
    30.         
    31.         /* PCLK1 = HCLK */
    32.         RCC_PCLK1Config(RCC_HCLK_Div1);
    33.         
    34.         /* PLLCLK = (8MHz / 2) * 9 = 36MHz */
    35.         RCC_PLLConfig(RCC_PLLSource_HSE_Div2, RCC_PLLMul_9);
    36.         
    37.         /* Enable PLL */
    38.         RCC_PLLCmd(ENABLE);
    39.         
    40.         /* Wait till PLL is ready */
    41.         while(RCC_GetFlagStatus(RCC_FLAG_PLLRDY) == RESET);
    42.         
    43.         /* Select PLL as system clock source */
    44.         RCC_SYSCLKConfig(RCC_SYSCLKSource_PLLCLK);
    45.         
    46.         /* Wait till PLL is used as system clock source */
    47.         if(RCC_GetSYSCLKSource() == 0x08)
    48.         {
    49.             
    50.         }
    51.         else
    52.         {
    53.             
    54.         }
    55.     }
    56.     else
    57.     {
    58.         /* If HSE fails to start-up. */
    59.         while(1)
    60.         {
    61.         }
    62.     }
    63. }
    SetSysClockTo48：
    1. /*******************************************************************************
    2. * Function Name : SetSysClockTo48
    3. * Description : Sets System clock frequency to 48MHz and configure HCLK, PCLK2 and PCLK1 prescalers.
    4. * Input : None
    5. * Output : None
    6. * Return : None
    7. *******************************************************************************/
    8. void SetSysClockTo48(void)
    9. {
    10.     /* RCC system reset */
    11.     RCC_DeInit();
    12.     /* Enable HSE */
    13.     RCC_HSEConfig(RCC_HSE_ON);
    14.     
    15.     /* Wait till HSE is ready */
    16.     HSEStartUpStatus = RCC_WaitForHSEStartUp();
    17.     if(HSEStartUpStatus == SUCCESS)
    18.     {
    19.         /* Enable Prefetch Buffer*/
    20.         FLASH_PrefetchBufferCmd(FLASH_PrefetchBuffer_Enable);
    21.         
    22.         /* Flash 1 wait state */
    23.         FLASH_SetLatency(FLASH_Latency_1);
    24.         
    25.         /* HCLK = SYSCLK */
    26.         RCC_HCLKConfig(RCC_SYSCLK_Div1);
    27.         
    28.         /* PCLK2 = HCLK */
    29.         RCC_PCLK2Config(RCC_HCLK_Div1);
    30.         
    31.         /* PCLK1 = HCLK/2 */
    32.         RCC_PCLK1Config(RCC_HCLK_Div2);
    33.         
    34.         /* PLLCLK = 8MHz * 6 = 48MHz */
    35.         RCC_PLLConfig(RCC_PLLSource_HSE_Div1, RCC_PLLMul_6);
    36.         
    37.         /* Enable PLL */
    38.         RCC_PLLCmd(ENABLE);
    39.         
    40.         /* Wait till PLL is ready */
    41.         while(RCC_GetFlagStatus(RCC_FLAG_PLLRDY) == RESET);
    42.         
    43.         /* Select PLL as system clock source */
    44.         RCC_SYSCLKConfig(RCC_SYSCLKSource_PLLCLK);
    45.         
    46.         /* Wait till PLL is used as system clock source */
    47.         if(RCC_GetSYSCLKSource() == 0x08)
    48.         {
    49.             
    50.         }
    51.         else
    52.         {
    53.             
    54.         }
    55.     }
    56.     else
    57.     {
    58.         /* If HSE fails to start-up. */
    59.         while(1)
    60.         {
    61.         }
    62.     }    
    63. }
    SetSysClockTo72：
    1. /*******************************************************************************
    2. * Function Name : SetSysClockTo72
    3. * Description : Sets System clock frequency to 72MHz and configure HCLK, PCLK2
    4. * and PCLK1 prescalers.
    5. * Input : None
    6. * Output : None
    7. * Return : None
    8. *******************************************************************************/
    9. void SetSysClockTo72(void)
    10. {
    11.     /* RCC system reset */
    12.     RCC_DeInit();
    13.     /* Enable HSE */
    14.     RCC_HSEConfig(RCC_HSE_ON);
    15.     
    16.     /* Wait till HSE is ready */
    17.     HSEStartUpStatus = RCC_WaitForHSEStartUp();
    18.     if(HSEStartUpStatus == SUCCESS)
    19.     {
    20.         /* Enable Prefetch Buffer*/
    21.         FLASH_PrefetchBufferCmd(FLASH_PrefetchBuffer_Enable);
    22.         
    23.         /* Flash 1 wait state */
    24.         FLASH_SetLatency(FLASH_Latency_2);
    25.         
    26.         /* HCLK = SYSCLK */
    27.         RCC_HCLKConfig(RCC_SYSCLK_Div1);
    28.         
    29.         /* PCLK2 = HCLK */
    30.         RCC_PCLK2Config(RCC_HCLK_Div1);
    31.         
    32.         /* PCLK1 = HCLK/2 */
    33.         RCC_PCLK1Config(RCC_HCLK_Div2);
    34.         
    35.         /* PLLCLK = 8MHz * 6 = 48MHz */
    36.         RCC_PLLConfig(RCC_PLLSource_HSE_Div1, RCC_PLLMul_9);
    37.         
    38.         /* Enable PLL */
    39.         RCC_PLLCmd(ENABLE);
    40.         
    41.         /* Wait till PLL is ready */
    42.         while(RCC_GetFlagStatus(RCC_FLAG_PLLRDY) == RESET);
    43.         
    44.         /* Select PLL as system clock source */
    45.         RCC_SYSCLKConfig(RCC_SYSCLKSource_PLLCLK);
    46.         
    47.         /* Wait till PLL is used as system clock source */
    48.         if(RCC_GetSYSCLKSource() == 0x08)
    49.         {
    50.             
    51.         }
    52.         else
    53.         {
    54.             
    55.         }
    56.     }
    57.     else
    58.     {
    59.         /* If HSE fails to start-up. */
    60.         while(1)
    61.         {
    62.         }
    63.     }    
    64. }

    二、中断初始化


    1. /****************************************************************************
    2. * Function Name : NVIC_Configuration
    3. * Description : Configures Vector Table base location.
    4. * Input : None
    5. * Output : None
    6. * Return : None
    7. ****************************************************************************/
    8. void NVIC_Configuration(void)
    9. {
    10.     NVIC_InitTypeDef NVIC_InitStructure;

    12. #ifdef VET_TAB_RAM
    13.     /* Set the Vector Table base location at 0x2000 0000 */
    14.     NVIC_SetVectorTable(NVIC_VectTab_RAM, 0x0);
    15. #else
    16.     /* Set the Vector Table base location at 0x8000 0000 */
    17.     NVIC_SetVectorTable(NVIC_VectTab_FLASH, 0x0);
    18. #endif
    19.     
    20.     /* Enable and configure RCC global IRQ channel */
    21.     NVIC_InitStructure.NVIC_IRQChannel = RCC_IRQn;
    22.     NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
    23.     NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
    24.     NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
    25.     NVIC_Init(&NVIC_InitStructure);
    26. }

    三、GPIO口初始化


    1. /****************************************************************************
    2. * Function Name : LED_Init
    3. * Description : Configures GPIOB
    4. * Input : None
    5. * Output : None
    6. * Return : None
    7. ****************************************************************************/
    8. void LED_Init()
    9. {
    10.     /* Configure all the GPIOB in Output Push-Pull */
    11.     GPIO_InitStructure.GPIO_Pin = GPIO_Pin_15 | GPIO_Pin_14;
    12.     GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    13.     GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;
    14.     
    15.     /* Enable GPIOB clock */
    16.     RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB, ENABLE);
    17.     
    18.     /* Initialize GPIOB*/
    19.     GPIO_Init(GPIOB, &GPIO_InitStructure);
    20. }

    四、main函数

    1. /****************************************************************************
    2. * Function Name : main
    3. * Description : Main program.
    4. * Input : None
    5. * Output : None
    6. * Return : None
    7. ****************************************************************************/

    9. int main(void)
    10. {
    11.     /* Set system clock HCLK PCLK2 PCLK1 and PLLCLK */
    12.     SetSysClock();
    13.     
    14.     /* Get current frequency and fill in RCC_ClockFreq */
    15.     RCC_GetClocksFreq(&RCC_ClockFreq);
    16.     
    17.     /* Enable Clock Security System(CSS), this will generate an NMI exception (Non-Maskable Interrupt)
    18.      when HSE clock fails*/
    19.     RCC_ClockSecuritySystemCmd(ENABLE);
    20.     
    21.     /* NVIC configuration */
    22.     NVIC_Configuration();
    23.     
    24.     /* LED configuration */
    25.     LED_Init();
    26.     
    27.     /* Set the GPIOB prot pin 15 and pin 14*/
    28.     GPIO_SetBits(GPIOB, GPIO_Pin_15 | GPIO_Pin_14);
    29.     
    30.     /* Output HSE clock on MCO pin */
    31.     RCC_MCOConfig(RCC_MCO_HSE);
    32.             
    33.     while(1)
    34.     {
    35.         GPIO_Write(GPIOB, (u16)~GPIO_ReadOutputData(GPIOB));

    37.         Delay(DELAY_COUNT);        
    38.     }
    39. }








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  • 原文地址：https://www.cnblogs.com/ch122633/p/7363272.html
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