STM32F4xx_System_Private_Functions

Functions
void	SystemInit (void)
	Setup the microcontroller system Initialize the Embedded Flash Interface, the PLL and update the SystemFrequency variable. More...
void	SystemCoreClockUpdate (void)
	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. More...
static void	SetSysClock (void)
	Configures the System clock source, PLL Multiplier and Divider factors, AHB/APBx prescalers and Flash settings This function should be called only once the RCC clock configuration is reset to the default reset state (done in SystemInit() function). More...

Detailed Description

Function Documentation

static void SetSysClock ( void  )

static

Configures the System clock source, PLL Multiplier and Divider factors, AHB/APBx prescalers and Flash settings This function should be called only once the RCC clock configuration is reset to the default reset state (done in SystemInit() function).

Return values

None

Definition at line 267 of file cmsis_system.c.

void SystemCoreClockUpdate

(

void

)

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.

- 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.

Return values

None

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.

- 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 stm32f30x.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 stm32f30x.h file (default value 8 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.

Return values

None

Definition at line 289 of file cmsis_system.c.

void SystemInit

(

void

)

Setup the microcontroller system Initialize the Embedded Flash Interface, the PLL and update the SystemFrequency variable.

Return values

None

Definition at line 213 of file cmsis_system.c.