Description:
Macro to configure the External High Speed oscillator
(HSE).
Parameters:
__STATE__: specifies the new state of the HSE. This
parameter can be one of the following values:
RCC_HSE_OFF: turn OFF the HSE oscillator,
HSERDY flag goes low after 6 HSE oscillator
clock cycles.
RCC_HSE_ON: turn ON the HSE oscillator.
RCC_HSE_BYPASS: HSE oscillator bypassed
with external clock.
Notes:
Transition HSE Bypass to HSE On and HSE On to
HSE Bypass are not supported by this macro. User
should request a transition to HSE Off first and then
HSE On or HSE Bypass. 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 reset the CSSON bit, so if the clock
security system(CSS) was previously enabled you
have to enable it again after calling this function.
To Next Page
Loading...
Need help?
General
