库函数默认8MHz晶振，应根据实际硬件选择
# CMSIS/stm32f10x.h
#define HSE_VALUE ((uint32_t)12000000)
#if !defined HSE_VALUE #ifdef STM32F10X_CL #define HSE_VALUE ((uint32_t)25000000) /*!< Value of the External oscillator in Hz */ #else #define HSE_VALUE ((uint32_t)8000000) /*!< Value of the External oscillator in Hz */ #endif /* STM32F10X_CL */ #endif /* HSE_VALUE */
原文：http://www.cnblogs.com/lvzaina/p/6198376.html