ST STM32F31xx User Manual

UM1581
Reset and clock control (RCC)
DocID023800 Rev 1
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Return values
 None.
Notes
 After enabling the HSE (RCC_HSE_ON or
RCC_HSE_Bypass), the application software should wait on
HSERDY flag to be set indicating that HSE clock is stable and
can be used to clock the PLL and/or system clock.
 HSE state can not be changed if it is used directly or through
the PLL as system clock. In this case, you have to select
another source of the system clock then change the HSE
state (ex. disable it).
 The HSE is stopped by hardware when entering STOP and
STANDBY modes.
 This function resets the CSSON bit, so if the Clock security
system(CSS) was previously enabled you have to enable it
again after calling this function.
18.2.6.3 RCC_WaitForHSEStartUp
Function Name
ErrorStatus RCC_WaitForHSEStartUp ( void )
Function Description
Waits for HSE start-up.
Parameters
 None.
Return values
 An ErrorStatus enumeration value:
 SUCCESS: HSE oscillator is stable and ready to use
 ERROR: HSE oscillator not yet ready
Notes
 This function waits on HSERDY flag to be set and return
SUCCESS if this flag is set, otherwise returns ERROR if the
timeout is reached and this flag is not set. The timeout value
is defined by the constant HSE_STARTUP_TIMEOUT in
stm32f30x.h file. You can tailor it depending on the HSE
crystal used in your application.
18.2.6.4 RCC_AdjustHSICalibrationValue
Function Name
void RCC_AdjustHSICalibrationValue ( uint8_t
HSICalibrationValue)
Function Description
Adjusts the Internal High Speed oscillator (HSI) calibration value.
Parameters
 HSICalibrationValue : specifies the HSI calibration trimming
value. This parameter must be a number between 0 and

ST STM32F31xx Specifications

General

Brand	ST
Model	STM32F31xx
Category	Microcontrollers
Language	English