STM32H7xx_System_Private_Functions

Functions
void	SystemInit (void)
	Setup the microcontroller system Initialize the FPU setting and vector table location configuration.
void	SystemCoreClockUpdate (void)
	Update SystemCoreClock variable according to Clock Register Values. The SystemCoreClock variable contains the core clock , it can be used by the user application to setup the SysTick timer or configure other parameters.
void	SystemInit_ExtMemCtl (void)
	Setup the external memory controller. Called in startup_stm32h7xx.s before jump to main. This function configures the external memories (SRAM/SDRAM) This SRAM/SDRAM will be used as program data memory (including heap and stack).

Detailed Description

Function Documentation

SystemCoreClockUpdate()

void SystemCoreClockUpdate

(

void

)

Update SystemCoreClock variable according to Clock Register Values. The SystemCoreClock variable contains the core clock , it can be used by the user application to setup the SysTick timer or configure other parameters.

Updates the SystemCoreClock variable.

Updates the SystemCoreClock with current core Clock retrieved from cpu registers.

Note

Each time the core clock 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 CSI, SystemCoreClock will contain the CSI_VALUE(*)
• 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 CSI_VALUE(*), HSI_VALUE(**) or HSE_VALUE(***) multiplied/divided by the PLL factors.

(*) CSI_VALUE is a constant defined in stm32h7xx_hal.h file (default value 4 MHz) but the real value may vary depending on the variations in voltage and temperature. (**) HSI_VALUE is a constant defined in stm32h7xx_hal.h file (default value 64 MHz) but the real value may vary depending on the variations in voltage and temperature.

(***)HSE_VALUE is a constant defined in stm32h7xx_hal.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.

  Parameters

  None

  Return values

  None

Note

Each time the core clock 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 CSI, SystemCoreClock will contain the CSI_VALUE(*)
  
• 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 CSI_VALUE(*), HSI_VALUE(**) or HSE_VALUE(***) multiplied/divided by the PLL factors.

(*) CSI_VALUE is a constant defined in stm32h7xx_hal.h file (default value 4 MHz) but the real value may vary depending on the variations in voltage and temperature.
(**) HSI_VALUE is a constant defined in stm32h7xx_hal.h file (default value 64 MHz) but the real value may vary depending on the variations in voltage and temperature.

(***)HSE_VALUE is a constant defined in stm32h7xx_hal.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.

  Parameters

  None

  Return values

  None

Note

Each time the core clock 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 CSI, SystemCoreClock will contain the CSI_VALUE(*)
• 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 CSI_VALUE(*), HSI_VALUE(**) or HSE_VALUE(***) multiplied/divided by the PLL factors.

(*) CSI_VALUE is a constant defined in stm32h7xx_hal.h file (default value 4 MHz) but the real value may vary depending on the variations in voltage and temperature. (**) HSI_VALUE is a constant defined in stm32h7xx_hal.h file (default value 64 MHz) but the real value may vary depending on the variations in voltage and temperature.

(***)HSE_VALUE is a constant defined in stm32h7xx_hal.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.

  Parameters

  None

  Return values

  None

Note

Each time the core clock 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 CSI, SystemCoreClock will contain the CSI_VALUE(*)
  
• 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 CSI_VALUE(*), HSI_VALUE(**) or HSE_VALUE(***) multiplied/divided by the PLL factors.

(*) CSI_VALUE is a constant defined in stm32h7xx_hal.h file (default value 4 MHz) but the real value may vary depending on the variations in voltage and temperature.
(**) HSI_VALUE is a constant defined in stm32h7xx_hal.h file (default value 64 MHz) but the real value may vary depending on the variations in voltage and temperature.

(***)HSE_VALUE is a constant defined in stm32h7xx_hal.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.

  Parameters

  None

  Return values

  None

Note

Each time the core clock 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 CSI, SystemCoreClock will contain the CSI_VALUE(*)
• 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 CSI_VALUE(*), HSI_VALUE(**) or HSE_VALUE(***) multiplied/divided by the PLL factors.

(*) CSI_VALUE is a constant defined in stm32h7xx_hal.h file (default value 4 MHz) but the real value may vary depending on the variations in voltage and temperature. (**) HSI_VALUE is a constant defined in stm32h7xx_hal.h file (default value 64 MHz) but the real value may vary depending on the variations in voltage and temperature.

(***)HSE_VALUE is a constant defined in stm32h7xx_hal.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.

  Parameters

  None

  Return values

  None

SystemInit()

void SystemInit

(

void

)

Setup the microcontroller system Initialize the FPU setting and vector table location configuration.

Setup the microcontroller system. Initialize the System and update the SystemFrequency variable.

Setup the microcontroller system.

Setup the microcontroller system. Initialize the System and update the SystemCoreClock variable.

Setup the microcontroller system Initialize the FPU setting, vector table location and External memory configuration.

Parameters

None

Return values

None

SystemInit_ExtMemCtl()

void SystemInit_ExtMemCtl

(

void

)

Setup the external memory controller. Called in startup_stm32h7xx.s before jump to main. This function configures the external memories (SRAM/SDRAM) This SRAM/SDRAM will be used as program data memory (including heap and stack).

Parameters

None

Return values

None