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/* ... */
/* ... */
/* ... */
/* ... */
#include "stm32f4xx.h"
#if !defined (HSE_VALUE)
#define HSE_VALUE ((uint32_t)25000000)
#endif
#if !defined (HSI_VALUE)
#define HSI_VALUE ((uint32_t)16000000)
#endif
/* ... */
/* ... */
/* ... */
/* ... */
/* ... */
/* ... */
#define VECT_TAB_OFFSET 0x00
/* ... */
Miscellaneous Configuration
/* ... */
/* ... */
/* ... */
/* ... */
/* ... */
uint32_t SystemCoreClock = 16000000;
const uint8_t AHBPrescTable[16] = {0, 0, 0, 0, 0, 0, 0, 0, 1, 2, 3, 4, 6, 7, 8, 9};
const uint8_t APBPrescTable[8] = {0, 0, 0, 0, 1, 2, 3, 4};
/* ... */
/* ... */
#if defined (DATA_IN_ExtSRAM)
static void SystemInit_ExtMemCtl(void);
#endif
/* ... */
/* ... */
/* ... */
void SystemInit(void)
{
#if (__FPU_PRESENT == 1) && (__FPU_USED == 1)
SCB->CPACR |= ((3UL << 10*2)|(3UL << 11*2));
#endifFPU settings
RCC->CR |= (uint32_t)0x00000001;
RCC->CFGR = 0x00000000;
RCC->CR &= (uint32_t)0xFEF6FFFF;
RCC->PLLCFGR = 0x24003010;
RCC->CR &= (uint32_t)0xFFFBFFFF;
RCC->CIR = 0x00000000;
#if defined (DATA_IN_ExtSRAM)
SystemInit_ExtMemCtl();
#endif
Reset the RCC clock configuration to the default reset state
#ifdef VECT_TAB_SRAM
SCB->VTOR = SRAM_BASE | VECT_TAB_OFFSET;
#else
SCB->VTOR = FLASH_BASE | VECT_TAB_OFFSET;
#endif
}{ ... }
/* ... */
void SystemCoreClockUpdate(void)
{
uint32_t tmp = 0, pllvco = 0, pllp = 2, pllsource = 0, pllm = 2;
tmp = RCC->CFGR & RCC_CFGR_SWS;
switch (tmp)
{
case 0x00:
SystemCoreClock = HSI_VALUE;
break;case 0x00:
case 0x04:
SystemCoreClock = HSE_VALUE;
break;case 0x04:
case 0x08:
/* ... */
pllsource = (RCC->PLLCFGR & RCC_PLLCFGR_PLLSRC) >> 22;
pllm = RCC->PLLCFGR & RCC_PLLCFGR_PLLM;
if (pllsource != 0)
{
pllvco = (HSE_VALUE / pllm) * ((RCC->PLLCFGR & RCC_PLLCFGR_PLLN) >> 6);
}if (pllsource != 0) { ... }
else
{
pllvco = (HSI_VALUE / pllm) * ((RCC->PLLCFGR & RCC_PLLCFGR_PLLN) >> 6);
}else { ... }
pllp = (((RCC->PLLCFGR & RCC_PLLCFGR_PLLP) >>16) + 1 ) *2;
SystemCoreClock = pllvco/pllp;
break;case 0x08:
default:
SystemCoreClock = HSI_VALUE;
break;default
}switch (tmp) { ... }
Get SYSCLK source
tmp = AHBPrescTable[((RCC->CFGR & RCC_CFGR_HPRE) >> 4)];
SystemCoreClock >>= tmp;
}{ ... }
#if defined (DATA_IN_ExtSRAM)
/* ... */
void SystemInit_ExtMemCtl(void)
{
RCC->AHB1ENR |= 0x00000078;
GPIOD->AFR[0] = 0x00CC00CC;
GPIOD->AFR[1] = 0xCCCCCCCC;
GPIOD->MODER = 0xAAAA0A0A;
GPIOD->OSPEEDR = 0xFFFF0F0F;
GPIOD->OTYPER = 0x00000000;
GPIOD->PUPDR = 0x00000000;
GPIOE->AFR[0] = 0xC00CC0CC;
GPIOE->AFR[1] = 0xCCCCCCCC;
GPIOE->MODER = 0xAAAA828A;
GPIOE->OSPEEDR = 0xFFFFC3CF;
GPIOE->OTYPER = 0x00000000;
GPIOE->PUPDR = 0x00000000;
GPIOF->AFR[0] = 0x00CCCCCC;
GPIOF->AFR[1] = 0xCCCC0000;
GPIOF->MODER = 0xAA000AAA;
GPIOF->OSPEEDR = 0xFF000FFF;
GPIOF->OTYPER = 0x00000000;
GPIOF->PUPDR = 0x00000000;
GPIOG->AFR[0] = 0x00CCCCCC;
GPIOG->AFR[1] = 0x000000C0;
GPIOG->MODER = 0x00080AAA;
GPIOG->OSPEEDR = 0x000C0FFF;
GPIOG->OTYPER = 0x00000000;
GPIOG->PUPDR = 0x00000000;
-- GPIOs Configuration
RCC->AHB3ENR |= 0x00000001;
FSMC_Bank1->BTCR[2] = 0x00001091;
FSMC_Bank1->BTCR[3] = 0x00110212;
FSMC_Bank1E->BWTR[2] = 0x0FFFFFFF;
}SystemInit_ExtMemCtl (void) { ... }
/* ... */#endif
/* ... */
/* ... */
/* ... */