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.
- 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.
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- 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:
(*) 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
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- Return values
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