本帖最后由 justdying 于 2022-11-18 18:56 编辑
修改时钟频率也很简单,这里说明下怎么修改,我使用的是外部晶振 8M
使用的标准库函数
修改system_stm32f4xx.c的文件
1、修改全局变量频率 ,SystemCoreClock
[C] 纯文本查看 复制代码 #if defined (STM32F40_41xxx)
uint32_t SystemCoreClock = 25000000;//168000000;
#endif /* STM32F40_41xxx */
#if defined (STM32F427_437xx) || defined (STM32F429_439xx)
uint32_t SystemCoreClock = 180000000;
#endif /* STM32F427_437x || STM32F429_439xx */
#if defined (STM32F401xx)
uint32_t SystemCoreClock = 84000000;
#endif /* STM32F401xx */
#if defined (STM32F411xE)
uint32_t SystemCoreClock = 100000000;
#endif /* STM32F401xx */
2、修改倍频参数
[C] 纯文本查看 复制代码 #define PLL_M 4 //8
#else /* STM32F411xE */
#if defined (USE_HSE_BYPASS)
#define PLL_M 8
#else /* STM32F411xE */
#define PLL_M 16
#endif /* USE_HSE_BYPASS */
#endif /* STM32F40_41xxx || STM32F427_437xx || STM32F429_439xx || STM32F401xx */
/* USB OTG FS, SDIO and RNG Clock = PLL_VCO / PLLQ */
#define PLL_Q 7
#if defined (STM32F40_41xxx)
#define PLL_N 50//336
/* SYSCLK = PLL_VCO / PLL_P */
#define PLL_P 4//2
#endif /* STM32F40_41xxx */
3、改完之后,注意系统延时函数的配置 |