AnsweredAssumed Answered

system_stm32fxxxx.c clock setting issue

Question asked by price.kyle on Apr 15, 2016
Latest reply on Apr 18, 2016 by price.kyle
I have been working with a few STM32 products for a little while now, and have tried the SPL and HAL and have noticed something that is simple to work around, but I think should be fixed in the next release of these files.  In the system_stm32fxxxx.c files for at least the f0xx and f4xx products, the global that stores the system clock (SystemCoreClock) is initialized to the max clock frequency of the device, and the SetSysClock() function attempts to change the clock to match this value.  If it fails, there is a section where user can handle this appropriately, though there is not any call made to the SystemCoreClockUpdate() function to update the value...  I have been changing this code when starting a project to add a call to the SystemCoreClockUpdate() at the end of the SetSysClock() function and initializingthe SystemCoreClock global to the default HSI since that is the default clock for the part.  Below is the system_stm32f4xx.c file for reference, please correct me if I am off-base here...

[code]
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           
/**
  ******************************************************************************
  * @file    system_stm32f4xx.c
  * @author  MCD Application Team
  * @version V1.1.0
  * @date    11-January-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 devices
  *-----------------------------------------------------------------------------
  *        System Clock source                    | PLL (HSE)
  *-----------------------------------------------------------------------------
  *        SYSCLK(Hz)                             | 168000000
  *-----------------------------------------------------------------------------
  *        HCLK(Hz)                               | 168000000
  *-----------------------------------------------------------------------------
  *        AHB Prescaler                          | 1
  *-----------------------------------------------------------------------------
  *        APB1 Prescaler                         | 4
  *-----------------------------------------------------------------------------
  *        APB2 Prescaler                         | 2
  *-----------------------------------------------------------------------------
  *        HSE Frequency(Hz)                      | 8000000
  *-----------------------------------------------------------------------------
  *        PLL_M                                  | 8
  *-----------------------------------------------------------------------------
  *        PLL_N                                  | 336
  *-----------------------------------------------------------------------------
  *        PLL_P                                  | 2
  *-----------------------------------------------------------------------------
  *        PLL_Q                                  | 7
  *-----------------------------------------------------------------------------
  *        PLLI2S_N                               | 271
  *-----------------------------------------------------------------------------
  *        PLLI2S_R                               | 2
  *-----------------------------------------------------------------------------
  *        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 mounted
     on STM324xG_EVAL/STM324x7I_EVAL boards as data memory  */
/* #define DATA_IN_ExtSRAM */
           
/*!< 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      8
#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
           
#define PLLI2S_N  271
#define PLLI2S_R  2
           
/******************************************************************************/
           
/**
  * @}
  */
           
/** @addtogroup STM32F4xx_System_Private_Macros
  * @{
  */
           
/**
  * @}
  */
           
/** @addtogroup STM32F4xx_System_Private_Variables
  * @{
  */
           
  uint32_t SystemCoreClock = 168000000;
           
const 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);
#ifdef DATA_IN_ExtSRAM
  static void SystemInit_ExtMemCtl(void);
#endif /* DATA_IN_ExtSRAM */
           
/**
  * @}
  */
           
/** @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;
           
#ifdef DATA_IN_ExtSRAM
  SystemInit_ExtMemCtl();
#endif /* DATA_IN_ExtSRAM */
        
  /* 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 the I2S PLL */
    RCC->PLLI2SCFGR = (PLLI2S_N << 6) | (PLLI2S_R << 28);
           
    /* Enable the I2S PLL */
    RCC->CR |= RCC_CR_PLLI2SON;
           
    /* Wait until the I2S PLL is ready */
    while (!(RCC->CR & RCC_CR_PLLI2SRDY));
  
    /* 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 */
  }
           
}
           
/**
  * @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  <-> FSMC_D2  | PE0  <-> FSMC_NBL0 | PF0 <-> FSMC_A0  | PG0 <-> FSMC_A10 |
| PD1  <-> FSMC_D3  | PE1  <-> FSMC_NBL1 | PF1 <-> FSMC_A1  | PG1 <-> FSMC_A11 |
| PD4  <-> FSMC_NOE | PE2  <-> FSMC_A23  | PF2 <-> FSMC_A2  | PG2 <-> FSMC_A12 |
| PD5  <-> FSMC_NWE | PE3  <-> FSMC_A19  | PF3 <-> FSMC_A3  | PG3 <-> FSMC_A13 |
| PD8  <-> FSMC_D13 | PE4  <-> FSMC_A20  | PF4 <-> FSMC_A4  | PG4 <-> FSMC_A14 |
| PD9  <-> FSMC_D14 | PE5  <-> FSMC_A21  | PF5 <-> FSMC_A5  | PG5 <-> FSMC_A15 |
| PD10 <-> FSMC_D15 | PE6  <-> FSMC_A22  | PF12 <-> FSMC_A6 | PG9 <-> FSMC_NE2 |
| PD11 <-> FSMC_A16 | PE7  <-> FSMC_D4   | PF13 <-> FSMC_A7 |------------------+
| PD12 <-> FSMC_A17 | PE8  <-> FSMC_D5   | PF14 <-> FSMC_A8 |
| PD13 <-> FSMC_A18 | PE9  <-> FSMC_D6   | PF15 <-> FSMC_A9 |
| PD14 <-> FSMC_D0  | PE10 <-> FSMC_D7   |------------------+
| PD15 <-> FSMC_D1  | PE11 <-> FSMC_D8   |
+-------------------| PE12 <-> FSMC_D9   |
                     | PE13 <-> FSMC_D10  |
                     | PE14 <-> FSMC_D11  |
                     | PE15 <-> FSMC_D12  |
                     +--------------------+
*/
   /* Enable GPIOD, GPIOE, GPIOF and GPIOG interface clock */
  RCC->AHB1ENR   |= 0x00000078;
 
  /* Connect PDx pins to FSMC 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 FSMC 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 FSMC 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 FSMC 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;
 
/*-- FSMC Configuration ------------------------------------------------------*/
  /* Enable the FSMC interface clock */
  RCC->AHB3ENR         |= 0x00000001;
           
  /* Configure and enable Bank1_SRAM2 */
  FSMC_Bank1->BTCR[2]  = 0x00001011;
  FSMC_Bank1->BTCR[3]  = 0x00000201;
  FSMC_Bank1E->BWTR[2] = 0x0fffffff;
/*
  Bank1_SRAM2 is configured as follow:
  p.FSMC_AddressSetupTime = 1;
  p.FSMC_AddressHoldTime = 0;
  p.FSMC_DataSetupTime = 2;
  p.FSMC_BusTurnAroundDuration = 0;
  p.FSMC_CLKDivision = 0;
  p.FSMC_DataLatency = 0;
  p.FSMC_AccessMode = FSMC_AccessMode_A;
  FSMC_NORSRAMInitStructure.FSMC_Bank = FSMC_Bank1_NORSRAM2;
  FSMC_NORSRAMInitStructure.FSMC_DataAddressMux = FSMC_DataAddressMux_Disable;
  FSMC_NORSRAMInitStructure.FSMC_MemoryType = FSMC_MemoryType_SRAM;
  FSMC_NORSRAMInitStructure.FSMC_MemoryDataWidth = FSMC_MemoryDataWidth_16b;
  FSMC_NORSRAMInitStructure.FSMC_BurstAccessMode = FSMC_BurstAccessMode_Disable;
  FSMC_NORSRAMInitStructure.FSMC_AsynchronousWait = FSMC_AsynchronousWait_Disable; 
  FSMC_NORSRAMInitStructure.FSMC_WaitSignalPolarity = FSMC_WaitSignalPolarity_Low;
  FSMC_NORSRAMInitStructure.FSMC_WrapMode = FSMC_WrapMode_Disable;
  FSMC_NORSRAMInitStructure.FSMC_WaitSignalActive = FSMC_WaitSignalActive_BeforeWaitState;
  FSMC_NORSRAMInitStructure.FSMC_WriteOperation = FSMC_WriteOperation_Enable;
  FSMC_NORSRAMInitStructure.FSMC_WaitSignal = FSMC_WaitSignal_Disable;
  FSMC_NORSRAMInitStructure.FSMC_ExtendedMode = FSMC_ExtendedMode_Disable;
  FSMC_NORSRAMInitStructure.FSMC_WriteBurst = FSMC_WriteBurst_Disable;
  FSMC_NORSRAMInitStructure.FSMC_ReadWriteTimingStruct = &p;
  FSMC_NORSRAMInitStructure.FSMC_WriteTimingStruct = &p;
*/
}
#endif /* DATA_IN_ExtSRAM */
           
           
/**
  * @}
  */
           
/**
  * @}
  */
 
/**
  * @}
  */   
/************************ (C) COPYRIGHT STMicroelectronics *****END OF FILE****/

[/code]

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