STM32时钟问题

只看该作者 · 2012-2-24 12:02

RCC_DeInit();
/* Enable HSE */
  RCC_HSEConfig(RCC_HSE_ON); /*HSE时钟为8MHZ*/
/* Wait till HSE is ready */
  HSEStartUpStatus = RCC_WaitForHSEStartUp();
  if(HSEStartUpStatus == SUCCESS)
  { /* HCLK = SYSCLK */
RCC_HCLKConfig(RCC_SYSCLK_Div1);
/* PCLK2 = HCLK */
RCC_PCLK2Config(RCC_HCLK_Div1);
/* PCLK1 = HCLK/2 */
RCC_PCLK1Config(RCC_HCLK_Div2);
/* Flash 2 wait state */
FLASH_SetLatency(FLASH_Latency_2);
/* Enable Prefetch Buffer */
FLASH_PrefetchBufferCmd(FLASH_PrefetchBuffer_Enable);
/* PLLCLK = 8MHz * 9 = 72 MHz */
RCC_PLLConfig(RCC_PLLSource_HSE_Div1, RCC_PLLMul_9);
/* Enable PLL */
RCC_PLLCmd(ENABLE);
/* Wait till PLL is ready */
while(RCC_GetFlagStatus(RCC_FLAG_PLLRDY) == RESET)
{
}
/* Select PLL as system clock source */
RCC_SYSCLKConfig(RCC_SYSCLKSource_PLLCLK);
/* Wait till PLL is used as system clock source */
while(RCC_GetSYSCLKSource() != 0x08)
{
}
  }
复位后系统时钟首先是采用HSI，后来根据配置才发生切换。是不是这样的？？？
上面代码中 RCC_HCLKConfig(RCC_SYSCLK_Div1); 这句函数后，AHB时钟到底是多少？72还是8MHZ？
求解答