• MCO from ST-LINK: MCO output of ST-LINK MCU is used as input clock. This
frequency cannot be changed, it is fixed at 8 MHz and connected to PF0/PD0/PH0-
OSC_IN of STM32 microcontroller.

我手頭有片Nucleo STM32F411RE BOARD,外部晶振8MZ,固定不能改,我在Keil C/C++ 頁面定義:USE_STDPERIPH_DRIVER,STM32F411xE,我移值标准固件库,
SYSTEM_STMF32F4XX.H,下列藍 {MOD}字體判斷STM32F411xE關鍵字有效,就會執行這句 #define HSE_VALUE    ((uint32_t)25000000) /*!< Value of the External oscillator in Hz
就跟原廠定義8MHZ不同,我需要調整為: 8MHZ,還是不用理它!!!!


#if defined(STM32F40_41xxx) || defined(STM32F427_437xx)  || defined(STM32F429_439xx) || defined(STM32F401xx)  || defined(STM32F411xE)
#if !defined  (HSE_VALUE)
  #define HSE_VALUE    ((uint32_t)25000000) /*!< Value of the External oscillator in Hz

#endif /* HSE_VALUE */
#elif defined(STM32F446xx)
#if !defined  (HSE_VALUE)
  #define HSE_VALUE    ((uint32_t)8000000) /*!< Value of the External oscillator in Hz */
#endif /* HSE_VALUE */
#endif /* STM32F40_41xxx || STM32F427_437xx || STM32F429_439xx || STM32F401xx || STM32F411xE */
/**