ST STM32F31xx User Manual

UM1581
Reset and clock control (RCC)
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selected, the switch will occur when the clock source will be
ready. You can use RCC_GetSYSCLKSource() function to
know which clock is currently used as system clock source.
18.2.7.2 RCC_GetSYSCLKSource
Function Name
uint8_t RCC_GetSYSCLKSource ( void )
Function Description
Returns the clock source used as system clock.
Parameters
 None.
Return values
 The clock source used as system clock. The returned
value can be one of the following values:
 0x00: HSI used as system clock
 0x04: HSE used as system clock
 0x08: PLL used as system clock
Notes
 None.
18.2.7.3 RCC_HCLKConfig
Function Name
void RCC_HCLKConfig ( uint32_t RCC_SYSCLK)
Function Description
Configures the AHB clock (HCLK).
Parameters
 RCC_SYSCLK : defines the AHB clock divider. This clock is
derived from the system clock (SYSCLK). This parameter can
be one of the following values:
 RCC_SYSCLK_Div1 : AHB clock = SYSCLK
 RCC_SYSCLK_Div2 : AHB clock = SYSCLK/2
 RCC_SYSCLK_Div4 : AHB clock = SYSCLK/4
 RCC_SYSCLK_Div8 : AHB clock = SYSCLK/8
 RCC_SYSCLK_Div16 : AHB clock = SYSCLK/16
 RCC_SYSCLK_Div64 : AHB clock = SYSCLK/64
 RCC_SYSCLK_Div128 : AHB clock = SYSCLK/128
 RCC_SYSCLK_Div256 : AHB clock = SYSCLK/256
 RCC_SYSCLK_Div512 : AHB clock = SYSCLK/512
Return values
 None.
Notes
 Depending on the device voltage range, the software has to
set correctly these bits to ensure that the system frequency
does not exceed the maximum allowed frequency (for more

ST STM32F31xx Specifications

General

Brand	ST
Model	STM32F31xx
Category	Microcontrollers
Language	English