void RCC_Configuration(void)
{
//----------使用外部RC晶振-----------
RCC_DeInit(); //初始化为缺省值
RCC_HSEConfig(RCC_HSE_ON); //使能外部的高速时钟
while(RCC_GetFlagStatus(RCC_FLAG_HSERDY) == RESET); //等待外部高速时钟使能就绪
FLASH_PrefetchBufferCmd(FLASH_PrefetchBuffer_Enable); //Enable Prefetch Buffer
FLASH_SetLatency(FLASH_Latency_2); //Flash 2 wait state
RCC_HCLKConfig(RCC_SYSCLK_Div1); //HCLK = SYSCLK
RCC_PCLK2Config(RCC_HCLK_Div1); //PCLK2 = HCLK
RCC_PCLK1Config(RCC_HCLK_Div2); //PCLK1 = HCLK/2
RCC_PLLConfig(RCC_PLLSource_HSE_Div1,RCC_PLLMul_9); //PLLCLK = 8MHZ * 9 =72MHZ
RCC_PLLCmd(ENABLE); //Enable PLLCLK
while(RCC_GetFlagStatus(RCC_FLAG_PLLRDY) == RESET); //Wait till PLLCLK is ready
RCC_SYSCLKConfig(RCC_SYSCLKSource_PLLCLK); //Select PLL as system clock
while(RCC_GetSYSCLKSource()!=0x08); //Wait till PLL is used as system clock source
//---------打开相应外设时钟--------------------
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA,ENABLE); //使能APB2外设的GPIOA的时钟
}
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