/**
  ******************************************************************************
  * @file    system_stm32f4xx.c
  * @Author  MCD Application Team
  * @version V1.2.0RC2
  * @date    20-February-2013
  * @brief   CMSIS Cortex-M4 Device Peripheral Access Layer System Source File.
  *          This file contains the system clock configuration for STM32F4xx devices,
  *          and is generated by the clock configuration tool
  *          stm32f4xx_Clock_Configuration_V1.1.0.xls
  *            
  * 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
  *                      and Divider factors, AHB/APBx prescalers and Flash settings),
  *                      depending on the configuration made in the clock xls tool.
  *                      This function is called at startup just after reset and
  *                      before branch to main program. This call is made inside
  *                      the "startup_stm32f4xx.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 (16 MHz) is used as system clock source.
  *    Then SystemInit() function is called, in "startup_stm32f4xx.s" file, to
  *    configure the system clock before to branch to main program.
  *
  * 3. If the system clock source selected by user fails to startup, the SystemInit()
  *    function will do nothing and HSI still used as system clock source. User can
  *    add some code to deal with this issue inside the SetSysClock() function.
  *
  * 4. The default value of HSE crystal is set to 25MHz, refer to "HSE_VALUE" define
  *    in "stm32f4xx.h" file. 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.
  *
  * 5. This file configures the system clock as follows:
  *=============================================================================
  *=============================================================================
  *        Supported STM32F40xx/41xx/427x/437x/429x/439x devices
  *-----------------------------------------------------------------------------
  *        System Clock source                    | PLL (HSE)
  *-----------------------------------------------------------------------------
  *        SYSCLK(Hz)                             | 168000000
  *-----------------------------------------------------------------------------
  *        HCLK(Hz)                               | 168000000
  *-----------------------------------------------------------------------------
  *        AHB Prescaler                          | 1
  *-----------------------------------------------------------------------------
  *        APB1 Prescaler                         | 4
  *-----------------------------------------------------------------------------
  *        APB2 Prescaler                         | 2
  *-----------------------------------------------------------------------------
  *        HSE Frequency(Hz)                      | 25000000
  *-----------------------------------------------------------------------------
  *        PLL_M                                  | 25
  *-----------------------------------------------------------------------------
  *        PLL_N                                  | 336
  *-----------------------------------------------------------------------------
  *        PLL_P                                  | 2
  *-----------------------------------------------------------------------------
  *        PLL_Q                                  | 7
  *-----------------------------------------------------------------------------
  *        PLLI2S_N                               | NA
  *-----------------------------------------------------------------------------
  *        PLLI2S_R                               | NA
  *-----------------------------------------------------------------------------
  *        I2S input clock                        | NA
  *-----------------------------------------------------------------------------
  *        VDD(V)                                 | 3.3
  *-----------------------------------------------------------------------------
  *        Main regulator output voltage          | Scale1 mode
  *-----------------------------------------------------------------------------
  *        Flash Latency(WS)                      | 5
  *-----------------------------------------------------------------------------
  *        Prefetch Buffer                        | ON
  *-----------------------------------------------------------------------------
  *        Instruction cache                      | ON
  *-----------------------------------------------------------------------------
  *        Data cache                             | ON
  *-----------------------------------------------------------------------------
  *        Require 48MHz for USB OTG FS,          | Disabled
  *        SDIO and RNG clock                     |
  *-----------------------------------------------------------------------------
  *=============================================================================
  ******************************************************************************
  * @attention
  *
  * <h2><center>&copy; COPYRIGHT 2013 STMicroelectronics</center></h2>
  *
  * Licensed under MCD-ST Liberty SW License Agreement V2, (the "License");
  * You may not use this file except in compliance with the License.
  * You may obtain a copy of the License at:
  *
  *        http://www.st.com/software_license_agreement_liberty_v2
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  *
  ******************************************************************************
  */

/** @addtogroup CMSIS
  * @{
  */

/** @addtogroup stm32f4xx_system
  * @{
  */  
  
/** @addtogroup STM32F4xx_System_Private_Includes
  * @{
  */

#include "stm32f4xx.h"

/**
  * @}
  */

/** @addtogroup STM32F4xx_System_Private_TypesDefinitions
  * @{
  */

/**
  * @}
  */

/** @addtogroup STM32F4xx_System_Private_Defines
  * @{
  */

/************************* Miscellaneous Configuration ************************/
/*!< Uncomment the following line if you need to use external SRAM or SDRAM mounted
     on STM324xG_EVAL/STM324x7I_EVAL/STM324x9I_EVAL boards as data memory  */
/* #define DATA_IN_ExtSRAM */
/* #define DATA_IN_ExtSDRAM */

/*!< Uncomment the following line if you need to relocate your vector Table in
     Internal SRAM. */
/* #define VECT_TAB_SRAM */
#define VECT_TAB_OFFSET  0x00 /*!< Vector Table base offset field.
                                   This value must be a multiple of 0x200. */
/******************************************************************************/

/************************* PLL Parameters *************************************/
/* PLL_VCO = (HSE_VALUE or HSI_VALUE / PLL_M) * PLL_N */
#define PLL_M      24
#define PLL_N      336

/* SYSCLK = PLL_VCO / PLL_P */
#define PLL_P      2

/* USB OTG FS, SDIO and RNG Clock =  PLL_VCO / PLLQ */
#define PLL_Q      7

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

/**
  * @}
  */

/** @addtogroup STM32F4xx_System_Private_Macros
  * @{
  */

/**
  * @}
  */

/** @addtogroup STM32F4xx_System_Private_Variables
  * @{
  */

  uint32_t SystemCoreClock = 168000000;

  __I uint8_t AHBPrescTable[16] = {0, 0, 0, 0, 0, 0, 0, 0, 1, 2, 3, 4, 6, 7, 8, 9};

/**
  * @}
  */

/** @addtogroup STM32F4xx_System_Private_FunctionPrototypes
  * @{
  */

static void SetSysClock(void);
#if defined (DATA_IN_ExtSRAM) || defined (DATA_IN_ExtSDRAM)
  static void SystemInit_ExtMemCtl(void);
#endif /* DATA_IN_ExtSRAM || DATA_IN_ExtSDRAM */

/**
  * @}
  */

/** @addtogroup STM32F4xx_System_Private_Functions
  * @{
  */

/**
  * @brief  Setup the microcontroller system
  *         Initialize the Embedded Flash Interface, the PLL and update the
  *         SystemFrequency variable.
  * @param  None
  * @retval None
  */
void SystemInit(void)
{
  /* FPU settings ------------------------------------------------------------*/
  #if (__FPU_PRESENT == 1) && (__FPU_USED == 1)
    SCB->CPACR |= ((3UL << 10*2)|(3UL << 11*2));  /* set CP10 and CP11 Full Access */
  #endif
  /* Reset the RCC clock configuration to the default reset state ------------*/
  /* Set HSION bit */
  RCC->CR |= (uint32_t)0x00000001;

  /* Reset CFGR register */
  RCC->CFGR = 0x00000000;

  /* Reset HSEON, CSSON and PLLON bits */
  RCC->CR &= (uint32_t)0xFEF6FFFF;

  /* Reset PLLCFGR register */
  RCC->PLLCFGR = 0x24003010;

  /* Reset HSEBYP bit */
  RCC->CR &= (uint32_t)0xFFFBFFFF;

  /* Disable all interrupts */
  RCC->CIR = 0x00000000;

#if defined (DATA_IN_ExtSRAM) || defined (DATA_IN_ExtSDRAM)
  SystemInit_ExtMemCtl();
#endif /* DATA_IN_ExtSRAM || DATA_IN_ExtSDRAM */
         
  /* Configure the System clock source, PLL Multiplier and Divider factors,
     AHB/APBx prescalers and Flash settings ----------------------------------*/
  SetSysClock();

  /* Configure the Vector Table location add offset address ------------------*/
#ifdef VECT_TAB_SRAM
  SCB->VTOR = SRAM_BASE | VECT_TAB_OFFSET; /* Vector Table Relocation in Internal SRAM */
#else
  SCB->VTOR = FLASH_BASE | VECT_TAB_OFFSET; /* Vector Table Relocation in Internal FLASH */
#endif
}

/**
   * @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/divided by the PLL factors.
  *         
  *         (*) HSI_VALUE is a constant defined in stm32f4xx.h file (default value
  *             16 MHz) but the real value may vary depending on the variations
  *             in voltage and temperature.   
  *   
  *         (**) HSE_VALUE is a constant defined in stm32f4xx.h file (default value
  *              25 MHz), 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 = 0, pllvco = 0, pllp = 2, pllsource = 0, pllm = 2;
  
  /* Get SYSCLK source -------------------------------------------------------*/
  tmp = RCC->CFGR & RCC_CFGR_SWS;

  switch (tmp)
  {
    case 0x00:  /* HSI used as system clock source */
      SystemCoreClock = HSI_VALUE;
      break;
    case 0x04:  /* HSE used as system clock source */
      SystemCoreClock = HSE_VALUE;
      break;
    case 0x08:  /* PLL used as system clock source */

      /* PLL_VCO = (HSE_VALUE or HSI_VALUE / PLL_M) * PLL_N
         SYSCLK = PLL_VCO / PLL_P
         */   
      pllsource = (RCC->PLLCFGR & RCC_PLLCFGR_PLLSRC) >> 22;
      pllm = RCC->PLLCFGR & RCC_PLLCFGR_PLLM;
      
      if (pllsource != 0)
      {
        /* HSE used as PLL clock source */
        pllvco = (HSE_VALUE / pllm) * ((RCC->PLLCFGR & RCC_PLLCFGR_PLLN) >> 6);
      }
      else
      {
        /* HSI used as PLL clock source */
        pllvco = (HSI_VALUE / pllm) * ((RCC->PLLCFGR & RCC_PLLCFGR_PLLN) >> 6);      
      }

      pllp = (((RCC->PLLCFGR & RCC_PLLCFGR_PLLP) >>16) + 1 ) *2;
      SystemCoreClock = pllvco/pllp;
      break;
    default:
      SystemCoreClock = HSI_VALUE;
      break;
  }
  /* Compute HCLK frequency --------------------------------------------------*/
  /* Get HCLK prescaler */
  tmp = AHBPrescTable[((RCC->CFGR & RCC_CFGR_HPRE) >> 4)];
  /* HCLK frequency */
  SystemCoreClock >>= tmp;
}

/**
  * @brief  Configures the System clock source, PLL Multiplier and Divider factors,
  *         AHB/APBx prescalers and Flash settings
  * @Note   This function should be called only once the RCC clock configuration  
  *         is reset to the default reset state (done in SystemInit() function).   
  * @param  None
  * @retval None
  */
static void SetSysClock(void)
{
/******************************************************************************/
/*            PLL (clocked by HSE) used as System clock source                */
/******************************************************************************/
  __IO uint32_t StartUpCounter = 0, HSEStatus = 0;
  
  /* Enable HSE */
  RCC->CR |= ((uint32_t)RCC_CR_HSEON);

  /* Wait till HSE is ready and if Time out is reached exit */
  do
  {
    HSEStatus = RCC->CR & RCC_CR_HSERDY;
    StartUpCounter++;
  } while((HSEStatus == 0) && (StartUpCounter != HSE_STARTUP_TIMEOUT));

  if ((RCC->CR & RCC_CR_HSERDY) != RESET)
  {
    HSEStatus = (uint32_t)0x01;
  }
  else
  {
    HSEStatus = (uint32_t)0x00;
  }

  if (HSEStatus == (uint32_t)0x01)
  {
    /* Select regulator voltage output Scale 1 mode, System frequency up to 168 MHz */
    RCC->APB1ENR |= RCC_APB1ENR_PWREN;
    PWR->CR |= PWR_CR_VOS;

    /* HCLK = SYSCLK / 1*/
    RCC->CFGR |= RCC_CFGR_HPRE_DIV1;
      
    /* PCLK2 = HCLK / 2*/
    RCC->CFGR |= RCC_CFGR_PPRE2_DIV2;
   
    /* PCLK1 = HCLK / 4*/
    RCC->CFGR |= RCC_CFGR_PPRE1_DIV4;

    /* Configure the main PLL */
    RCC->PLLCFGR = PLL_M | (PLL_N << 6) | (((PLL_P >> 1) -1) << 16) |
                   (RCC_PLLCFGR_PLLSRC_HSE) | (PLL_Q << 24);

    /* Enable the main PLL */
    RCC->CR |= RCC_CR_PLLON;

    /* Wait till the main PLL is ready */
    while((RCC->CR & RCC_CR_PLLRDY) == 0)
    {
    }
   
    /* Configure Flash prefetch, Instruction cache, Data cache and wait state */
    FLASH->ACR = FLASH_ACR_PRFTEN | FLASH_ACR_ICEN |FLASH_ACR_DCEN |FLASH_ACR_LATENCY_5WS;

    /* Select the main PLL as system clock source */
    RCC->CFGR &= (uint32_t)((uint32_t)~(RCC_CFGR_SW));
    RCC->CFGR |= RCC_CFGR_SW_PLL;

    /* Wait till the main PLL is used as system clock source */
    while ((RCC->CFGR & (uint32_t)RCC_CFGR_SWS ) != RCC_CFGR_SWS_PLL);
    {
    }
  }
  else
  { /* If HSE fails to start-up, the application will have wrong clock
         configuration. User can add here some code to deal with this error */
    RCC->CR &= ~((uint32_t)RCC_CR_HSEON);
    RCC->CR &= ~((uint32_t)RCC_CR_HSION);
    StartUpCounter = 0;
    do
    {
      HSEStatus = RCC->CR & RCC_CR_HSIRDY;
      StartUpCounter++;
    } while((HSEStatus == 0) && (StartUpCounter != HSE_STARTUP_TIMEOUT));
    /* Select regulator voltage output Scale 1 mode, System frequency up to 168 MHz */
    RCC->APB1ENR |= RCC_APB1ENR_PWREN;
    PWR->CR |= PWR_CR_VOS;

    /* HCLK = SYSCLK / 1*/
    RCC->CFGR |= RCC_CFGR_HPRE_DIV1;
      
    /* PCLK2 = HCLK / 2*/
    RCC->CFGR |= RCC_CFGR_PPRE2_DIV2;
   
    /* PCLK1 = HCLK / 4*/
    RCC->CFGR |= RCC_CFGR_PPRE1_DIV4;

    /* Configure the main PLL */
    RCC->PLLCFGR = 16 | (PLL_N << 6) | (((PLL_P >> 1) -1) << 16) |
                   (RCC_PLLCFGR_PLLSRC_HSI) | (PLL_Q << 24);

    /* Enable the main PLL */
    RCC->CR |= RCC_CR_PLLON;

    /* Wait till the main PLL is ready */
    while((RCC->CR & RCC_CR_PLLRDY) == 0)
    {
    }
   
    /* Configure Flash prefetch, Instruction cache, Data cache and wait state */
    FLASH->ACR = FLASH_ACR_PRFTEN | FLASH_ACR_ICEN |FLASH_ACR_DCEN |FLASH_ACR_LATENCY_5WS;

    /* Select the main PLL as system clock source */
    RCC->CFGR &= (uint32_t)((uint32_t)~(RCC_CFGR_SW));
    RCC->CFGR |= RCC_CFGR_SW_PLL;

    /* Wait till the main PLL is used as system clock source */
    while ((RCC->CFGR & (uint32_t)RCC_CFGR_SWS ) != RCC_CFGR_SWS_PLL);
    {
    }   
  }

}

/**
  * @brief  Setup the external memory controller. Called in startup_stm32f4xx.s
  *          before jump to __main
  * @param  None
  * @retval None
  */
#ifdef DATA_IN_ExtSRAM
/**
  * @brief  Setup the external memory controller.
  *         Called in startup_stm32f4xx.s before jump to main.
  *         This function configures the external SRAM mounted on STM324xG_EVAL/STM324x7I boards
  *         This SRAM will be used as program data memory (including heap and stack).
  * @param  None
  * @retval None
  */
void SystemInit_ExtMemCtl(void)
{
/*-- GPIOs Configuration -----------------------------------------------------*/
/*
+-------------------+--------------------+------------------+--------------+
+                       SRAM pins assignment                               +
+-------------------+--------------------+------------------+--------------+
| PD0  <-> FMC_D2  | PE0  <-> FMC_NBL0 | PF0  <-> FMC_A0 | PG0 <-> FMC_A10 |
| PD1  <-> FMC_D3  | PE1  <-> FMC_NBL1 | PF1  <-> FMC_A1 | PG1 <-> FMC_A11 |
| PD4  <-> FMC_NOE | PE3  <-> FMC_A19  | PF2  <-> FMC_A2 | PG2 <-> FMC_A12 |
| PD5  <-> FMC_NWE | PE4  <-> FMC_A20  | PF3  <-> FMC_A3 | PG3 <-> FMC_A13 |
| PD8  <-> FMC_D13 | PE7  <-> FMC_D4   | PF4  <-> FMC_A4 | PG4 <-> FMC_A14 |
| PD9  <-> FMC_D14 | PE8  <-> FMC_D5   | PF5  <-> FMC_A5 | PG5 <-> FMC_A15 |
| PD10 <-> FMC_D15 | PE9  <-> FMC_D6   | PF12 <-> FMC_A6 | PG9 <-> FMC_NE2 |
| PD11 <-> FMC_A16 | PE10 <-> FMC_D7   | PF13 <-> FMC_A7 |-----------------+
| PD12 <-> FMC_A17 | PE11 <-> FMC_D8   | PF14 <-> FMC_A8 |
| PD13 <-> FMC_A18 | PE12 <-> FMC_D9   | PF15 <-> FMC_A9 |
| PD14 <-> FMC_D0  | PE13 <-> FMC_D10  |-----------------+
| PD15 <-> FMC_D1  | PE14 <-> FMC_D11  |
|                  | PE15 <-> FMC_D12  |
+------------------+------------------+
*/
   /* Enable GPIOD, GPIOE, GPIOF and GPIOG interface clock */
  RCC->AHB1ENR   |= 0x00000078;
  
  /* Connect PDx pins to FMC Alternate function */
  GPIOD->AFR[0]  = 0x00cc00cc;
  GPIOD->AFR[1]  = 0xcccccccc;
  /* Configure PDx pins in Alternate function mode */  
  GPIOD->MODER   = 0xaaaa0a0a;
  /* Configure PDx pins speed to 100 MHz */  
  GPIOD->OSPEEDR = 0xffff0f0f;
  /* Configure PDx pins Output type to push-pull */  
  GPIOD->OTYPER  = 0x00000000;
  /* No pull-up, pull-down for PDx pins */
  GPIOD->PUPDR   = 0x00000000;

  /* Connect PEx pins to FMC Alternate function */
  GPIOE->AFR[0]  = 0xcccccccc;
  GPIOE->AFR[1]  = 0xcccccccc;
  /* Configure PEx pins in Alternate function mode */
  GPIOE->MODER   = 0xaaaaaaaa;
  /* Configure PEx pins speed to 100 MHz */
  GPIOE->OSPEEDR = 0xffffffff;
  /* Configure PEx pins Output type to push-pull */  
  GPIOE->OTYPER  = 0x00000000;
  /* No pull-up, pull-down for PEx pins */
  GPIOE->PUPDR   = 0x00000000;

  /* Connect PFx pins to FMC Alternate function */
  GPIOF->AFR[0]  = 0x00cccccc;
  GPIOF->AFR[1]  = 0xcccc0000;
  /* Configure PFx pins in Alternate function mode */   
  GPIOF->MODER   = 0xaa000aaa;
  /* Configure PFx pins speed to 100 MHz */
  GPIOF->OSPEEDR = 0xff000fff;
  /* Configure PFx pins Output type to push-pull */  
  GPIOF->OTYPER  = 0x00000000;
  /* No pull-up, pull-down for PFx pins */
  GPIOF->PUPDR   = 0x00000000;

  /* Connect PGx pins to FMC Alternate function */
  GPIOG->AFR[0]  = 0x00cccccc;
  GPIOG->AFR[1]  = 0x000000c0;
  /* Configure PGx pins in Alternate function mode */
  GPIOG->MODER   = 0x00080aaa;
  /* Configure PGx pins speed to 100 MHz */
  GPIOG->OSPEEDR = 0x000c0fff;
  /* Configure PGx pins Output type to push-pull */  
  GPIOG->OTYPER  = 0x00000000;
  /* No pull-up, pull-down for PGx pins */
  GPIOG->PUPDR   = 0x00000000;
  
/*-- FMC Configuration ------------------------------------------------------*/
  /* Enable the FMC interface clock */
  RCC->AHB3ENR         |= 0x00000001;

  /* Configure and enable Bank1_SRAM2 */
  FMC_Bank1->BTCR[2]  = 0x00001011;
  FMC_Bank1->BTCR[3]  = 0x00000201;
  FMC_Bank1E->BWTR[2] = 0x0fffffff;
/*
  Bank1_SRAM2 is configured as follow:

  NORSRAMTimingStructure.FMC_AddressSetupTime = 1;
  NORSRAMTimingStructure.FMC_AddressHoldTime = 0;
  NORSRAMTimingStructure.FMC_DataSetupTime = 2;
  NORSRAMTimingStructure.FMC_BusTurnAroundDuration = 0;
  NORSRAMTimingStructure.FMC_CLKDivision = 0;
  NORSRAMTimingStructure.FMC_DataLatency = 0;
  NORSRAMTimingStructure.FMC_AccessMode = FMC_AccessMode_A;

  FMC_NORSRAMInitStructure.FMC_Bank = FMC_Bank1_NORSRAM2;
  FMC_NORSRAMInitStructure.FMC_DataAddressMux = FMC_DataAddressMux_Disable;
  FMC_NORSRAMInitStructure.FMC_MemoryType = FMC_MemoryType_SRAM;
  FMC_NORSRAMInitStructure.FMC_MemoryDataWidth = FMC_MemoryDataWidth_16b;
  FMC_NORSRAMInitStructure.FMC_BurstAccessMode = FMC_BurstAccessMode_Disable;
  FMC_NORSRAMInitStructure.FMC_AsynchronousWait = FMC_AsynchronousWait_Disable;  
  FMC_NORSRAMInitStructure.FMC_WaitSignalPolarity = FMC_WaitSignalPolarity_Low;
  FMC_NORSRAMInitStructure.FMC_WrapMode = FMC_WrapMode_Disable;
  FMC_NORSRAMInitStructure.FMC_WaitSignalActive = FMC_WaitSignalActive_BeforeWaitState;
  FMC_NORSRAMInitStructure.FMC_WriteOperation = FMC_WriteOperation_Enable;
  FMC_NORSRAMInitStructure.FMC_WaitSignal = FMC_WaitSignal_Disable;
  FMC_NORSRAMInitStructure.FMC_ExtendedMode = FMC_ExtendedMode_Disable;
  FMC_NORSRAMInitStructure.FMC_WriteBurst = FMC_WriteBurst_Disable;
  FMC_NORSRAMInitStructure.FMC_ContinousClock = FMC_CClock_SyncOnly;
  FMC_NORSRAMInitStructure.FMC_ReadWriteTimingStruct = &NORSRAMTimingStructure;
  FMC_NORSRAMInitStructure.FMC_WriteTimingStruct = &NORSRAMTimingStructure;
*/
  
}
#endif /* DATA_IN_ExtSRAM */
  
#ifdef DATA_IN_ExtSDRAM
/**
  * @brief  Setup the external memory controller.
  *         Called in startup_stm32f4xx.s before jump to main.
  *         This function configures the external SDRAM mounted on STM324x9I_EVAL board
  *         This SDRAM will be used as program data memory (including heap and stack).
  * @param  None
  * @retval None
  */
void SystemInit_ExtMemCtl(void)
{
  register uint32_t tmpreg = 0, timeout = 0xFFFF;
  register uint32_t index;

  /* Enable GPIOC, GPIOD, GPIOE, GPIOF, GPIOG, GPIOH and GPIOI interface
      clock */
  RCC->AHB1ENR |= 0x000001FC;
  
  /* Connect PCx pins to FMC Alternate function */
  GPIOC->AFR[0]  = 0x0000000c;
  GPIOC->AFR[1]  = 0x00007700;
  /* Configure PCx pins in Alternate function mode */  
  GPIOC->MODER   = 0x00a00002;
  /* Configure PCx pins speed to 50 MHz */  
  GPIOC->OSPEEDR = 0x00a00002;
  /* Configure PCx pins Output type to push-pull */  
  GPIOC->OTYPER  = 0x00000000;
  /* No pull-up, pull-down for PCx pins */
  GPIOC->PUPDR   = 0x00500000;
  
  /* Connect PDx pins to FMC Alternate function */
  GPIOD->AFR[0]  = 0x000000CC;
  GPIOD->AFR[1]  = 0xCC000CCC;
  /* Configure PDx pins in Alternate function mode */  
  GPIOD->MODER   = 0xA02A000A;
  /* Configure PDx pins speed to 50 MHz */  
  GPIOD->OSPEEDR = 0xA02A000A;
  /* Configure PDx pins Output type to push-pull */  
  GPIOD->OTYPER  = 0x00000000;
  /* No pull-up, pull-down for PDx pins */
  GPIOD->PUPDR   = 0x00000000;

  /* Connect PEx pins to FMC Alternate function */
  GPIOE->AFR[0]  = 0xC00000CC;
  GPIOE->AFR[1]  = 0xCCCCCCCC;
  /* Configure PEx pins in Alternate function mode */
  GPIOE->MODER   = 0xAAAA800A;
  /* Configure PEx pins speed to 50 MHz */
  GPIOE->OSPEEDR = 0xAAAA800A;
  /* Configure PEx pins Output type to push-pull */  
  GPIOE->OTYPER  = 0x00000000;
  /* No pull-up, pull-down for PEx pins */
  GPIOE->PUPDR   = 0x00000000;

  /* Connect PFx pins to FMC Alternate function */
  GPIOF->AFR[0]  = 0xcccccccc;
  GPIOF->AFR[1]  = 0xcccccccc;
  /* Configure PFx pins in Alternate function mode */   
  GPIOF->MODER   = 0xAA800AAA;
  /* Configure PFx pins speed to 50 MHz */
  GPIOF->OSPEEDR = 0xAA800AAA;
  /* Configure PFx pins Output type to push-pull */  
  GPIOF->OTYPER  = 0x00000000;
  /* No pull-up, pull-down for PFx pins */
  GPIOF->PUPDR   = 0x00000000;

  /* Connect PGx pins to FMC Alternate function */
  GPIOG->AFR[0]  = 0xcccccccc;
  GPIOG->AFR[1]  = 0xcccccccc;
  /* Configure PGx pins in Alternate function mode */
  GPIOG->MODER   = 0xaaaaaaaa;
  /* Configure PGx pins speed to 50 MHz */
  GPIOG->OSPEEDR = 0xaaaaaaaa;
  /* Configure PGx pins Output type to push-pull */  
  GPIOG->OTYPER  = 0x00000000;
  /* No pull-up, pull-down for PGx pins */
  GPIOG->PUPDR   = 0x00000000;
  
  /* Connect PHx pins to FMC Alternate function */
  GPIOH->AFR[0]  = 0x00C0CC00;
  GPIOH->AFR[1]  = 0xCCCCCCCC;
  /* Configure PHx pins in Alternate function mode */
  GPIOH->MODER   = 0xAAAA08A0;
  /* Configure PHx pins speed to 50 MHz */
  GPIOH->OSPEEDR = 0xAAAA08A0;
  /* Configure PHx pins Output type to push-pull */  
  GPIOH->OTYPER  = 0x00000000;
  /* No pull-up, pull-down for PHx pins */
  GPIOH->PUPDR   = 0x00000000;
  
  /* Connect PIx pins to FMC Alternate function */
  GPIOI->AFR[0]  = 0xCCCCCCCC;
  GPIOI->AFR[1]  = 0x00000CC0;
  /* Configure PIx pins in Alternate function mode */
  GPIOI->MODER   = 0x0028AAAA;
  /* Configure PIx pins speed to 50 MHz */
  GPIOI->OSPEEDR = 0x0028AAAA;
  /* Configure PIx pins Output type to push-pull */  
  GPIOI->OTYPER  = 0x00000000;
  /* No pull-up, pull-down for PIx pins */
  GPIOI->PUPDR   = 0x00000000;
  
/*-- FMC Configuration ------------------------------------------------------*/
  /* Enable the FMC interface clock */
  RCC->AHB3ENR |= 0x00000001;
  
  /* Configure and enable SDRAM bank1 */
  FMC_Bank5_6->SDCR[0] = 0x000029D0;
  FMC_Bank5_6->SDTR[0] = 0x01115351;      
  
  /* SDRAM initialization sequence */
  /* Clock enable command */
  FMC_Bank5_6->SDCMR = 0x00000011;
  tmpreg = FMC_Bank5_6->SDSR & 0x00000020;
  while((tmpreg != 0) & (timeout-- > 0))
  {
    tmpreg = FMC_Bank5_6->SDSR & 0x00000020;
  }
  
  /* Delay */
  for (index = 0; index<1000; index++);
  
  /* PALL command */
  FMC_Bank5_6->SDCMR = 0x00000012;           
  timeout = 0xFFFF;
  while((tmpreg != 0) & (timeout-- > 0))
  {
  tmpreg = FMC_Bank5_6->SDSR & 0x00000020;
  }
  
  /* Auto refresh command */
  FMC_Bank5_6->SDCMR = 0x00000073;
  timeout = 0xFFFF;
  while((tmpreg != 0) & (timeout-- > 0))
  {
  tmpreg = FMC_Bank5_6->SDSR & 0x00000020;
  }

  /* MRD register program */
  FMC_Bank5_6->SDCMR = 0x00046014;
  timeout = 0xFFFF;
  while((tmpreg != 0) & (timeout-- > 0))
  {
  tmpreg = FMC_Bank5_6->SDSR & 0x00000020;
  }
  
  /* Set refresh count */
  tmpreg = FMC_Bank5_6->SDRTR;
  FMC_Bank5_6->SDRTR = (tmpreg | (0x0000027C<<1));
  
  /* Disable write protection */
  tmpreg = FMC_Bank5_6->SDCR[0];
  FMC_Bank5_6->SDCR[0] = (tmpreg & 0xFFFFFDFF);
  
/*
  Bank1_SDRAM is configured as follow:

  FMC_SDRAMTimingInitStructure.FMC_LoadToActiveDelay = 2;      
  FMC_SDRAMTimingInitStructure.FMC_ExitSelfRefreshDelay = 6;  
  FMC_SDRAMTimingInitStructure.FMC_SelfRefreshTime = 4;        
  FMC_SDRAMTimingInitStructure.FMC_RowCycleDelay = 6;         
  FMC_SDRAMTimingInitStructure.FMC_WriteRecoveryTime = 2;      
  FMC_SDRAMTimingInitStructure.FMC_RPDelay = 2;               
  FMC_SDRAMTimingInitStructure.FMC_RCDDelay = 2;               

  FMC_SDRAMInitStructure.FMC_Bank = SDRAM_BANK;
  FMC_SDRAMInitStructure.FMC_ColumnBitsNumber = FMC_ColumnBits_Number_8b;
  FMC_SDRAMInitStructure.FMC_RowBitsNumber = FMC_RowBits_Number_11b;
  FMC_SDRAMInitStructure.FMC_SDMemoryDataWidth = FMC_SDMemory_Width_16b;
  FMC_SDRAMInitStructure.FMC_InternalBankNumber = FMC_InternalBank_Number_4;
  FMC_SDRAMInitStructure.FMC_CASLatency = FMC_CAS_Latency_3;
  FMC_SDRAMInitStructure.FMC_WriteProtection = FMC_Write_Protection_Disable;
  FMC_SDRAMInitStructure.FMC_SDClockPeriod = FMC_SDClock_Period_2;
  FMC_SDRAMInitStructure.FMC_ReadBurst = FMC_Read_Burst_disable;
  FMC_SDRAMInitStructure.FMC_ReadPipeDelay = FMC_ReadPipe_Delay_1;
  FMC_SDRAMInitStructure.FMC_SDRAMTimingStruct = &FMC_SDRAMTimingInitStructure;
*/
  
}
#endif /* DATA_IN_ExtSDRAM */


/**
  * @}
  */

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

以上是1.2版本的system_stm32f4xx.c