STM32C5xx_System_Private_Functions

Functions
void	SystemInit (void)
	Setup the microcontroller system.
void	SystemCoreClockUpdate (void)
	Update SystemCoreClock variable according to Clock Register Values.

Detailed Description

Function Documentation

SystemCoreClockUpdate()

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 PSI, SystemCoreClock will contain the PSI_VALUE(*)
• If SYSCLK source is HSI, SystemCoreClock will contain the HSI_VALUE(**)
• If SYSCLK source is HSI_DIV_X, SystemCoreClock will contain the HSI_VALUE/X(**)
• If SYSCLK source is HSE, SystemCoreClock will contain the HSE_VALUE(***)

(*) PSI_VALUE is one of the value [100, 144, 160] MHz. The value of PSI can change slightly depending on the clock source reference of the PSI.

(**) HSI_VALUE is a constant defined in stm32c5xxxx.h file (default value 144 MHz) but the real value can vary depending on the variations in voltage and temperature.

(***) HSE_VALUE is a constant defined in stm32_external_env.h file (default value 24 MHz or 48MHz), user has to ensure that HSE_VALUE is same as the real frequency of the crystal used. Otherwise, this function can have wrong result.

• The result of this function could be not correct when using fractional value for HSE crystal.