system_stm32f1xx.c

/**
  ******************************************************************************
  * @file    system_stm32f1xx.c
  * @author  MCD Application Team
  * @brief   CMSIS Cortex-M3 Device Peripheral Access Layer System Source File.
  * 
  * 1.  This file provides two functions and one global variable to be called from 
  *     user application:
  *      - SystemInit(): Setups the system clock (System clock source, PLL Multiplier
  *                      factors, AHB/APBx prescalers and Flash settings). 
  *                      This function is called at startup just after reset and 
  *                      before branch to main program. This call is made inside
  *                      the "startup_stm32f1xx_xx.s" file.
  *
  *      - SystemCoreClock variable: Contains the core clock (HCLK), it can be used
  *                                  by the user application to setup the SysTick 
  *                                  timer or configure other parameters.
  *                                     
  *      - SystemCoreClockUpdate(): Updates the variable SystemCoreClock and must
  *                                 be called whenever the core clock is changed
  *                                 during program execution.
  *
  * 2. After each device reset the HSI (8 MHz) is used as system clock source.
  *    Then SystemInit() function is called, in "startup_stm32f1xx_xx.s" file, to
  *    configure the system clock before to branch to main program.
  *
  * 4. The default value of HSE crystal is set to 8 MHz (or 25 MHz, depending on
  *    the product used), refer to "HSE_VALUE". 
  *    When HSE is used as system clock source, directly or through PLL, and you
  *    are using different crystal you have to adapt the HSE value to your own
  *    configuration.
  *        
  ******************************************************************************
  * @attention
  *
  * <h2><center>&copy; Copyright (c) 2017 STMicroelectronics.
  * All rights reserved.</center></h2>
  *
  * This software component is licensed by ST under BSD 3-Clause license,
  * the "License"; You may not use this file except in compliance with the
  * License. You may obtain a copy of the License at:
  *                        opensource.org/licenses/BSD-3-Clause
  *
  ******************************************************************************
  */

/** @addtogroup CMSIS
  * @{
  */

/** @addtogroup stm32f1xx_system
  * @{
  */  
  
/** @addtogroup STM32F1xx_System_Private_Includes
  * @{
  */

#include "stm32f1xx.h"

/**
  * @}
  */

/** @addtogroup STM32F1xx_System_Private_TypesDefinitions
  * @{
  */

/**
  * @}
  */

/** @addtogroup STM32F1xx_System_Private_Defines
  * @{
  */

#if !defined  (HSE_VALUE) 
  #define HSE_VALUE               8000000U /*!< Default value of the External oscillator in Hz.
                                                This value can be provided and adapted by the user application. */
#endif /* HSE_VALUE */

#if !defined  (HSI_VALUE)
  #define HSI_VALUE               8000000U /*!< Default value of the Internal oscillator in Hz.
                                                This value can be provided and adapted by the user application. */
#endif /* HSI_VALUE */

/*!< Uncomment the following line if you need to use external SRAM  */ 
#if defined(STM32F100xE) || defined(STM32F101xE) || defined(STM32F101xG) || defined(STM32F103xE) || defined(STM32F103xG)
/* #define DATA_IN_ExtSRAM */
#endif /* STM32F100xE || STM32F101xE || STM32F101xG || STM32F103xE || STM32F103xG */

/* Note: Following vector table addresses must be defined in line with linker
         configuration. */
/*!< Uncomment the following line if you need to relocate the vector table
     anywhere in Flash or Sram, else the vector table is kept at the automatic
     remap of boot address selected */
/* #define USER_VECT_TAB_ADDRESS */

#if defined(USER_VECT_TAB_ADDRESS)
/*!< Uncomment the following line if you need to relocate your vector Table
     in Sram else user remap will be done in Flash. */
/* #define VECT_TAB_SRAM */
#if defined(VECT_TAB_SRAM)
#define VECT_TAB_BASE_ADDRESS   SRAM_BASE       /*!< Vector Table base address field.
                                                     This value must be a multiple of 0x200. */
#define VECT_TAB_OFFSET         0x00000000U     /*!< Vector Table base offset field.
                                                     This value must be a multiple of 0x200. */
#else
#define VECT_TAB_BASE_ADDRESS   FLASH_BASE      /*!< Vector Table base address field.
                                                     This value must be a multiple of 0x200. */
#define VECT_TAB_OFFSET         0x00000000U     /*!< Vector Table base offset field.
                                                     This value must be a multiple of 0x200. */
#endif /* VECT_TAB_SRAM */
#endif /* USER_VECT_TAB_ADDRESS */

/******************************************************************************/

/**
  * @}
  */

/** @addtogroup STM32F1xx_System_Private_Macros
  * @{
  */

/**
  * @}
  */

/** @addtogroup STM32F1xx_System_Private_Variables
  * @{
  */

  /* This variable is updated in three ways:
      1) by calling CMSIS function SystemCoreClockUpdate()
      2) by calling HAL API function HAL_RCC_GetHCLKFreq()
      3) each time HAL_RCC_ClockConfig() is called to configure the system clock frequency 
         Note: If you use this function to configure the system clock; then there
               is no need to call the 2 first functions listed above, since SystemCoreClock
               variable is updated automatically.
  */
uint32_t SystemCoreClock = 8000000;
const uint8_t AHBPrescTable[16U] = {0, 0, 0, 0, 0, 0, 0, 0, 1, 2, 3, 4, 6, 7, 8, 9};
const uint8_t APBPrescTable[8U] =  {0, 0, 0, 0, 1, 2, 3, 4};

/**
  * @}
  */

/** @addtogroup STM32F1xx_System_Private_FunctionPrototypes
  * @{
  */

#if defined(STM32F100xE) || defined(STM32F101xE) || defined(STM32F101xG) || defined(STM32F103xE) || defined(STM32F103xG)
#ifdef DATA_IN_ExtSRAM
  static void SystemInit_ExtMemCtl(void); 
#endif /* DATA_IN_ExtSRAM */
#endif /* STM32F100xE || STM32F101xE || STM32F101xG || STM32F103xE || STM32F103xG */

/**
  * @}
  */

/** @addtogroup STM32F1xx_System_Private_Functions
  * @{
  */

/**
  * @brief  Setup the microcontroller system
  *         Initialize the Embedded Flash Interface, the PLL and update the 
  *         SystemCoreClock variable.
  * @note   This function should be used only after reset.
  * @param  None
  * @retval None
  */
void SystemInit (void)
{
#if defined(STM32F100xE) || defined(STM32F101xE) || defined(STM32F101xG) || defined(STM32F103xE) || defined(STM32F103xG)
  #ifdef DATA_IN_ExtSRAM
    SystemInit_ExtMemCtl(); 
  #endif /* DATA_IN_ExtSRAM */
#endif 

  /* Configure the Vector Table location -------------------------------------*/
#if defined(USER_VECT_TAB_ADDRESS)
  SCB->VTOR = VECT_TAB_BASE_ADDRESS | VECT_TAB_OFFSET; /* Vector Table Relocation in Internal SRAM. */
#endif /* USER_VECT_TAB_ADDRESS */
}

/**
  * @brief  Update SystemCoreClock variable according to Clock Register Values.
  *         The SystemCoreClock variable contains the core clock (HCLK), it can
  *         be used by the user application to setup the SysTick timer or configure
  *         other parameters.
  *           
  * @note   Each time the core clock (HCLK) changes, this function must be called
  *         to update SystemCoreClock variable value. Otherwise, any configuration
  *         based on this variable will be incorrect.         
  *     
  * @note   - The system frequency computed by this function is not the real 
  *           frequency in the chip. It is calculated based on the predefined 
  *           constant and the selected clock source:
  *             
  *           - If SYSCLK source is HSI, SystemCoreClock will contain the HSI_VALUE(*)
  *                                              
  *           - If SYSCLK source is HSE, SystemCoreClock will contain the HSE_VALUE(**)
  *                          
  *           - If SYSCLK source is PLL, SystemCoreClock will contain the HSE_VALUE(**) 
  *             or HSI_VALUE(*) multiplied by the PLL factors.
  *         
  *         (*) HSI_VALUE is a constant defined in stm32f1xx.h file (default value
  *             8 MHz) but the real value may vary depending on the variations
  *             in voltage and temperature.   
  *    
  *         (**) HSE_VALUE is a constant defined in stm32f1xx.h file (default value
  *              8 MHz or 25 MHz, depending on the product used), user has to ensure
  *              that HSE_VALUE is same as the real frequency of the crystal used.
  *              Otherwise, this function may have wrong result.
  *                
  *         - The result of this function could be not correct when using fractional
  *           value for HSE crystal.
  * @param  None
  * @retval None
  */
void SystemCoreClockUpdate (void)
{
  uint32_t tmp = 0U, pllmull = 0U, pllsource = 0U;

#if defined(STM32F105xC) || defined(STM32F107xC)
  uint32_t prediv1source = 0U, prediv1factor = 0U, prediv2factor = 0U, pll2mull = 0U;
#endif /* STM32F105xC */

#if defined(STM32F100xB) || defined(STM32F100xE)
  uint32_t prediv1factor = 0U;
#endif /* STM32F100xB or STM32F100xE */
    
  /* Get SYSCLK source -------------------------------------------------------*/
  tmp = RCC->CFGR & RCC_CFGR_SWS;
  
  switch (tmp)
  {
    case 0x00U:  /* HSI used as system clock */
      SystemCoreClock = HSI_VALUE;
      break;
    case 0x04U:  /* HSE used as system clock */
      SystemCoreClock = HSE_VALUE;
      break;
    case 0x08U:  /* PLL used as system clock */

      /* Get PLL clock source and multiplication factor ----------------------*/
      pllmull = RCC->CFGR & RCC_CFGR_PLLMULL;
      pllsource = RCC->CFGR & RCC_CFGR_PLLSRC;
      
#if !defined(STM32F105xC) && !defined(STM32F107xC)      
      pllmull = ( pllmull >> 18U) + 2U;
      
      if (pllsource == 0x00U)
      {
        /* HSI oscillator clock divided by 2 selected as PLL clock entry */
        SystemCoreClock = (HSI_VALUE >> 1U) * pllmull;
      }
      else
      {
 #if defined(STM32F100xB) || defined(STM32F100xE)
       prediv1factor = (RCC->CFGR2 & RCC_CFGR2_PREDIV1) + 1U;
       /* HSE oscillator clock selected as PREDIV1 clock entry */
       SystemCoreClock = (HSE_VALUE / prediv1factor) * pllmull; 
 #else
        /* HSE selected as PLL clock entry */
        if ((RCC->CFGR & RCC_CFGR_PLLXTPRE) != (uint32_t)RESET)
        {/* HSE oscillator clock divided by 2 */
          SystemCoreClock = (HSE_VALUE >> 1U) * pllmull;
        }
        else
        {
          SystemCoreClock = HSE_VALUE * pllmull;
        }
 #endif
      }
#else
      pllmull = pllmull >> 18U;
      
      if (pllmull != 0x0DU)
      {
         pllmull += 2U;
      }
      else
      { /* PLL multiplication factor = PLL input clock * 6.5 */
        pllmull = 13U / 2U; 
      }
            
      if (pllsource == 0x00U)
      {
        /* HSI oscillator clock divided by 2 selected as PLL clock entry */
        SystemCoreClock = (HSI_VALUE >> 1U) * pllmull;
      }
      else
      {/* PREDIV1 selected as PLL clock entry */
        
        /* Get PREDIV1 clock source and division factor */
        prediv1source = RCC->CFGR2 & RCC_CFGR2_PREDIV1SRC;
        prediv1factor = (RCC->CFGR2 & RCC_CFGR2_PREDIV1) + 1U;
        
        if (prediv1source == 0U)
        { 
          /* HSE oscillator clock selected as PREDIV1 clock entry */
          SystemCoreClock = (HSE_VALUE / prediv1factor) * pllmull;          
        }
        else
        {/* PLL2 clock selected as PREDIV1 clock entry */
          
          /* Get PREDIV2 division factor and PLL2 multiplication factor */
          prediv2factor = ((RCC->CFGR2 & RCC_CFGR2_PREDIV2) >> 4U) + 1U;
          pll2mull = ((RCC->CFGR2 & RCC_CFGR2_PLL2MUL) >> 8U) + 2U; 
          SystemCoreClock = (((HSE_VALUE / prediv2factor) * pll2mull) / prediv1factor) * pllmull;                         
        }
      }
#endif /* STM32F105xC */ 
      break;

    default:
      SystemCoreClock = HSI_VALUE;
      break;
  }
  
  /* Compute HCLK clock frequency ----------------*/
  /* Get HCLK prescaler */
  tmp = AHBPrescTable[((RCC->CFGR & RCC_CFGR_HPRE) >> 4U)];
  /* HCLK clock frequency */
  SystemCoreClock >>= tmp;  
}

#if defined(STM32F100xE) || defined(STM32F101xE) || defined(STM32F101xG) || defined(STM32F103xE) || defined(STM32F103xG)
/**
  * @brief  Setup the external memory controller. Called in startup_stm32f1xx.s 
  *          before jump to __main
  * @param  None
  * @retval None
  */ 
#ifdef DATA_IN_ExtSRAM
/**
  * @brief  Setup the external memory controller. 
  *         Called in startup_stm32f1xx_xx.s/.c before jump to main.
  *         This function configures the external SRAM mounted on STM3210E-EVAL
  *         board (STM32 High density devices). This SRAM will be used as program
  *         data memory (including heap and stack).
  * @param  None
  * @retval None
  */ 
void SystemInit_ExtMemCtl(void) 
{
  __IO uint32_t tmpreg;
  /*!< FSMC Bank1 NOR/SRAM3 is used for the STM3210E-EVAL, if another Bank is 
    required, then adjust the Register Addresses */

  /* Enable FSMC clock */
  RCC->AHBENR = 0x00000114U;

  /* Delay after an RCC peripheral clock enabling */
  tmpreg = READ_BIT(RCC->AHBENR, RCC_AHBENR_FSMCEN);
  
  /* Enable GPIOD, GPIOE, GPIOF and GPIOG clocks */
  RCC->APB2ENR = 0x000001E0U;
  
  /* Delay after an RCC peripheral clock enabling */
  tmpreg = READ_BIT(RCC->APB2ENR, RCC_APB2ENR_IOPDEN);

  (void)(tmpreg);
  
/* ---------------  SRAM Data lines, NOE and NWE configuration ---------------*/
/*----------------  SRAM Address lines configuration -------------------------*/
/*----------------  NOE and NWE configuration --------------------------------*/  
/*----------------  NE3 configuration ----------------------------------------*/
/*----------------  NBL0, NBL1 configuration ---------------------------------*/
  
  GPIOD->CRL = 0x44BB44BBU;  
  GPIOD->CRH = 0xBBBBBBBBU;

  GPIOE->CRL = 0xB44444BBU;  
  GPIOE->CRH = 0xBBBBBBBBU;

  GPIOF->CRL = 0x44BBBBBBU;  
  GPIOF->CRH = 0xBBBB4444U;

  GPIOG->CRL = 0x44BBBBBBU;  
  GPIOG->CRH = 0x444B4B44U;
   
/*----------------  FSMC Configuration ---------------------------------------*/  
/*----------------  Enable FSMC Bank1_SRAM Bank ------------------------------*/
  
  FSMC_Bank1->BTCR[4U] = 0x00001091U;
  FSMC_Bank1->BTCR[5U] = 0x00110212U;
}
#endif /* DATA_IN_ExtSRAM */
#endif /* STM32F100xE || STM32F101xE || STM32F101xG || STM32F103xE || STM32F103xG */

/**
  * @}
  */

/**
  * @}
  */
  
/**
  * @}
  */    
/************************ (C) COPYRIGHT STMicroelectronics *****END OF FILE****/