stm32系統(tǒng)時鐘配置問題

RCC->CR |= (uint32_t)0x00000001;

#ifndef STM32F10X_CL
RCC->CFGR &= (uint32_t)0xF8FF0000;
#else
RCC->CFGR &= (uint32_t)0xF0FF0000;
#endif


RCC->CR &= (uint32_t)0xFEF6FFFF;

RCC->CR &= (uint32_t)0xFFFBFFFF;

RCC->CFGR &= (uint32_t)0xFF80FFFF;

#ifdef STM32F10X_CL

RCC->CR &= (uint32_t)0xEBFFFFFF;

RCC->CIR = 0x00FF0000;

RCC->CFGR2 = 0x00000000;
#elif defined (STM32F10X_LD_VL) || defined (STM32F10X_MD_VL) || (defined STM32F10X_HD_VL)

RCC->CIR = 0x009F0000;

RCC->CFGR2 = 0x00000000;
#else

RCC->CIR = 0x009F0000;
#endif

#if defined (STM32F10X_HD) || (defined STM32F10X_XL) || (defined STM32F10X_HD_VL)
#ifdef DATA_IN_ExtSRAM
SystemInit_ExtMemCtl();
#endif
#endif

接著void SystemInit (void)調(diào)用 SetSysClock();函數(shù)，將系統(tǒng)時鐘配置到72m，將AHB,APB1，APB2等外設(shè)之前的時鐘都配置好，然后切換到72mz下運行。所以在使用哪個外設(shè)的時候，只需要使能相應(yīng)的外設(shè)時鐘就可以了