cmsis_system.c

Go to the documentation of this file.

#include "stm32f4xx.h"

/************************* Miscellaneous Configuration ************************/
/* #define DATA_IN_ExtSRAM */

/* #define VECT_TAB_SRAM */
#define VECT_TAB_OFFSET  0x00 
/******************************************************************************/

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

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

  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};

static void SetSysClock(void);
#ifdef DATA_IN_ExtSRAM
  static void SystemInit_ExtMemCtl(void);
#endif /* DATA_IN_ExtSRAM */

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
}

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;
}

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_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 */

          /* better to hang here than to start with a wrong clock */
          while (1);
  }

}

#ifdef DATA_IN_ExtSRAM

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 | PE3  <-> FSMC_A19  | PF2  <-> FSMC_A2 | PG2 <-> FSMC_A12 |
 | PD5  <-> FSMC_NWE | PE4  <-> FSMC_A20  | PF3  <-> FSMC_A3 | PG3 <-> FSMC_A13 |
 | PD8  <-> FSMC_D13 | PE7  <-> FSMC_D4   | PF4  <-> FSMC_A4 | PG4 <-> FSMC_A14 |
 | PD9  <-> FSMC_D14 | PE8  <-> FSMC_D5   | PF5  <-> FSMC_A5 | PG5 <-> FSMC_A15 |
 | PD10 <-> FSMC_D15 | PE9  <-> FSMC_D6   | PF12 <-> FSMC_A6 | PG9 <-> FSMC_NE2 |
 | PD11 <-> FSMC_A16 | PE10 <-> FSMC_D7   | PF13 <-> FSMC_A7 |------------------+
 | PD12 <-> FSMC_A17 | PE11 <-> FSMC_D8   | PF14 <-> FSMC_A8 |
 | PD13 <-> FSMC_A18 | PE12 <-> FSMC_D9   | PF15 <-> FSMC_A9 |
 | PD14 <-> FSMC_D0  | PE13 <-> FSMC_D10  |------------------+
 | PD15 <-> FSMC_D1  | 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]  = 0xcc0ccccc;
  /* 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]  = 0xc00cc0cc;
  GPIOE->AFR[1]  = 0xcccccccc;
  /* Configure PEx pins in Alternate function mode */
  GPIOE->MODER   = 0xaaaa828a;
  /* Configure PEx pins speed to 100 MHz */
  GPIOE->OSPEEDR = 0xffffc3cf;
  /* 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]  = 0x00001015;
  FSMC_Bank1->BTCR[3]  = 0x00010603;
  FSMC_Bank1E->BWTR[2] = 0x0fffffff;
/*
  Bank1_SRAM2 is configured as follow:

  p.FSMC_AddressSetupTime = 3;
  p.FSMC_AddressHoldTime = 0;
  p.FSMC_DataSetupTime = 6;
  p.FSMC_BusTurnAroundDuration = 1;
  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_PSRAM;
  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 2011 STMicroelectronics *****END OF FILE****/