system.c

/**
  ******************************************************************************
  * @file    system_stm32f1xx.c
  * @author  MCD Application Team
  * @version V4.2.0
  * @date    31-March-2017
  * @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</center></h2>
  *
  * Redistribution and use in source and binary forms, with or without modification,
  * are permitted provided that the following conditions are met:
  *   1. Redistributions of source code must retain the above copyright notice,
  *      this list of conditions and the following disclaimer.
  *   2. Redistributions in binary form must reproduce the above copyright notice,
  *      this list of conditions and the following disclaimer in the documentation
  *      and/or other materials provided with the distribution.
  *   3. Neither the name of STMicroelectronics nor the names of its contributors
  *      may be used to endorse or promote products derived from this software
  *      without specific prior written permission.
  *
  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  *
  ******************************************************************************
  */

/** @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 */

/**
  * @}
  */

/** @addtogroup STM32F1xx_System_Private_Macros
  * @{
  */

/**
  * @}
  */

/** @addtogroup STM32F1xx_System_Private_Variables
  * @{
  */

/*******************************************************************************
*  Clock Definitions
*******************************************************************************/
#if defined(STM32F100xB) ||defined(STM32F100xE)
  uint32_t SystemCoreClock         = 24000000U;        /*!< System Clock Frequency (Core Clock) */
#else /*!< HSI Selected as System Clock source */
  uint32_t SystemCoreClock         = 72000000U;        /*!< System Clock Frequency (Core Clock) */
#endif

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)
{
  extern uint32_t g_pfnVectors[];

  /* Reset the RCC clock configuration to the default reset state(for debug purpose) */
  /* Set HSION bit */
  RCC->CR |= 0x00000001U;

  /* Reset SW, HPRE, PPRE1, PPRE2, ADCPRE and MCO bits */
#if !defined(STM32F105xC) && !defined(STM32F107xC)
  RCC->CFGR &= 0xF8FF0000U;
#else
  RCC->CFGR &= 0xF0FF0000U;
#endif /* STM32F105xC */   
  
  /* Reset HSEON, CSSON and PLLON bits */
  RCC->CR &= 0xFEF6FFFFU;

  /* Reset HSEBYP bit */
  RCC->CR &= 0xFFFBFFFFU;

  /* Reset PLLSRC, PLLXTPRE, PLLMUL and USBPRE/OTGFSPRE bits */
  RCC->CFGR &= 0xFF80FFFFU;

#if defined(STM32F105xC) || defined(STM32F107xC)
  /* Reset PLL2ON and PLL3ON bits */
  RCC->CR &= 0xEBFFFFFFU;

  /* Disable all interrupts and clear pending bits  */
  RCC->CIR = 0x00FF0000U;

  /* Reset CFGR2 register */
  RCC->CFGR2 = 0x00000000U;
#elif defined(STM32F100xB) || defined(STM32F100xE)
  /* Disable all interrupts and clear pending bits  */
  RCC->CIR = 0x009F0000U;

  /* Reset CFGR2 register */
  RCC->CFGR2 = 0x00000000U;      
#else
  /* Disable all interrupts and clear pending bits  */
  RCC->CIR = 0x009F0000U;
#endif /* STM32F105xC */
    
#if defined(STM32F100xE) || defined(STM32F101xE) || defined(STM32F101xG) || defined(STM32F103xE) || defined(STM32F103xG)
  #ifdef DATA_IN_ExtSRAM
    SystemInit_ExtMemCtl(); 
  #endif /* DATA_IN_ExtSRAM */
#endif 

  SCB->VTOR = (uint32_t)g_pfnVectors; /* Vector Table Relocation */
}

/**
  * @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****/