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RCC Driver (stm32f407xx_rcc_driver.h/.c)

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stm32f407xx_rcc_driver.h

Path: Project/Drivers/Inc/

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/*******************************************************************************
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 * File     : stm32f407xx_rcc_driver.h
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 * Brief    : STM32F407xx MCU specific RCC driver header file
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 * Author   ; Kyungjae Lee
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 * Date     : Jun 20, 2023
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 *
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 * Note     : This code includes only the features that are necessary for my
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 *            personal projects.
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 * ****************************************************************************/
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#ifndef STM32F407XX_RCC_DRIVER_H
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#define STM32F407XX_RCC_DRIVER_H
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#include "stm32f407xx.h"
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/*******************************************************************************
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 * APIs supported by the SPI driver
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 * (See function definitions for more information)
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 ******************************************************************************/
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uint32_t RCC_GetPCLK1Value(void);
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uint32_t RCC_GetPCLK2Value(void);
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uint32_t RCC_GetPLLOutputClk(void);
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#endif /* STM32F407XX_RCC_DRIVER_H */

stm32f407xx_rcc_driver.c

Path: Project/Drivers/Src/

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/*******************************************************************************
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 * File     : stm32f407xx_spi_driver.c
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 * Brief    : STM32F407xx MCU specific RCC driver source file
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 * Author   ; Kyungjae Lee
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 * Date     : Jun 20, 2023
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 *
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 * Note     : This code includes only the features that are necessary for my
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 *            personal projects.
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 * ****************************************************************************/
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#include "stm32f407xx.h"
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/* RCC_CFGR HPRE[7:4] */
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uint16_t AHB_Prescalar[8] = {2, 4, 8, 16, 64, 128, 256, 512};
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/* RCC_CFGR PPRE1[10:8] */
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uint16_t APB1_Prescalar[4] = {2, 4, 8, 16};
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/**
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 * RCC_GetPCLK1Value()
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 * Brief    : Computes and returns APB1 peripheral clock frequency
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 * Param    : None
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 * Retval   : APB1 peripheral clock frequency
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 * Note     : N/A
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 */
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uint32_t RCC_GetPCLK1Value(void)
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{
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    uint32_t pclk1;     /* APB1 peripheral clock frequency */
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    uint32_t sysClk;    /* System clock frequency */
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    uint8_t clkSrc;     /* Clock source */
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    uint8_t temp;
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    uint16_t ahbp;      /* AHB prescalar */
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    uint16_t apb1p;     /* APB1 prescalar */
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    clkSrc = (RCC->CFGR >> RCC_CFGR_SWS) & 0x03;
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    if (clkSrc == 0)
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    {
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        /* 00: HSI oscillator used as the system clock */
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        sysClk = 16000000;  /* System clock = 16 MHz */
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    }
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    else if (clkSrc == 1)
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    {
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        /* 01: HSE oscillator used as the system clock */
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        sysClk = 8000000;   /* In the case of STM32 Discovery board */
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    }
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    else if (clkSrc == 2)
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    {
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        /* 10: PLL used as the system clock */
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        sysClk = RCC_GetPLLOutputClk();
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    }
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    /* Obtain AHB prescalar */
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    temp = ((RCC->CFGR >> RCC_CFGR_HPRE) & 0xF);
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    if (temp < 8)
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    {
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        ahbp = 1;
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    }
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    else
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    {
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        ahbp = AHB_Prescalar[temp - 8];
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    }
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    /* Obtain APB1 prescalar */
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    temp = ((RCC->CFGR >> RCC_CFGR_PPRE1) & 0x7);
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    if (temp < 4)
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    {
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        apb1p = 1;
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    }
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    else
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    {
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        apb1p = APB1_Prescalar[temp - 4];
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    }
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    /* Compute APB1 peripheral clock frequency */
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    pclk1 = (sysClk / ahbp) / apb1p;
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    return pclk1;
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} /* End of RCC_GetPCLK1Value */
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/**
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 * RCC_GetPCLK2Value()
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 * Brief    : Computes and returns APB2 peripheral clock frequency
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 * Param    : None
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 * Retval   : APB2 peripheral clock frequency
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 * Note     : N/A
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 */
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uint32_t RCC_GetPCLK2Value(void)
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{
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    uint32_t pclk2;     /* APB2 peripheral clock frequency */
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    uint32_t sysClk;    /* System clock frequency */
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    uint8_t clkSrc;     /* Clock source */
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    uint8_t temp;
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    uint16_t ahbp;      /* AHB prescalar */
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    uint16_t apb2p;     /* APB2 prescalar */
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    clkSrc = (RCC->CFGR >> RCC_CFGR_SWS) & 0x03;
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    if (clkSrc == 0)
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    {
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        /* 00: HSI oscillator used as the system clock */
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        sysClk = 16000000;  /* System clock = 16 MHz */
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    }
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    else
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    {
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        sysClk = 8000000;   /* In the case of STM32 Discovery board */
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    }
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    /* Obtain AHB prescalar */
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    temp = ((RCC->CFGR >> RCC_CFGR_HPRE) & 0xF);
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    if (temp < 8)
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    {
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        ahbp = 1;
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    }
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    else
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    {
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        ahbp = AHB_Prescalar[temp - 8];
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    }
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    /* Obtain APB2 prescalar */
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    temp = ((RCC->CFGR >> RCC_CFGR_PPRE2) & 0x7);
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    if (temp < 4)
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    {
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        apb2p = 1;
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    }
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    else
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    {
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        apb2p = APB1_Prescalar[temp - 4];
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    }
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    /* Compute APB2 peripheral clock frequency */
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    pclk2 = (sysClk / ahbp) / apb2p;
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    return pclk2;
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} /* End of RCC_GetPCLK2Value */
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/**
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 * RCC_GetPLLOutputClk()
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 * Brief    : Controls PLL ouput clock
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 * Param    : None
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 * Retval   : None
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 * Note     : To be implemented as per the project requirements. Not used
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 *            at this point.
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 */
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uint32_t RCC_GetPLLOutputClk(void)
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{
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    return 0;
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} /* End of RCC_GetPLLOutputClk */