ST STM32F2 User Manual

UM1940
HAL RCC Generic Driver
DocID028236 Rev 2
423/1371
HAL_RCC_DisableCSS
Function name
void HAL_RCC_DisableCSS (void )
Function description
Disables the Clock Security System.
Return values
None:
HAL_RCC_GetSysClockFreq
Function name
uint32_t HAL_RCC_GetSysClockFreq (void )
Function description
Returns the SYSCLK frequency.
Return values
SYSCLK: frequency
Notes
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, function returns values based on
HSI_VALUE(*)
If SYSCLK source is HSE, function returns values based on
HSE_VALUE(**)
If SYSCLK source is PLL, function returns values based on
HSE_VALUE(**) or HSI_VALUE(*) multiplied/divided by the
PLL factors.
(*) HSI_VALUE is a constant defined in stm32f2xx_hal_conf.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
stm32f2xx_hal_conf.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.
This function can be used by the user application to compute
the baudrate for the communication peripherals or configure
other parameters.
Each time SYSCLK changes, this function must be called to
update the right SYSCLK value. Otherwise, any configuration
based on this function will be incorrect.
HAL_RCC_GetHCLKFreq
Function name
uint32_t HAL_RCC_GetHCLKFreq (void )
Function description
Returns the HCLK frequency.
Return values
HCLK: frequency
Notes
Each time HCLK changes, this function must be called to
update the right HCLK value. Otherwise, any configuration
based on this function will be incorrect.
The SystemCoreClock CMSIS variable is used to store
System Clock Frequency and updated within this function

ST STM32F2 Specifications

General

Brand	ST
Model	STM32F2
Category	Microcontrollers
Language	English