[时钟函数]RCC_APB2PeriphClockCmd()

//功能为打开或关闭对应的外设输出时钟端口void RCC_APB2PeriphClockCmd(uint32_t RCC_APB2Periph, FunctionalState NewState){    assert_param(IS_RCC_APB2_PERIPH(RCC_APB2Periph)); //参数纠正  assert_param(IS_FUNCTIONAL_STATE(NewState));      //参数验证  /*参考结构体RCC_TypeDef,APB2NR为外设时钟使能寄存器，偏移地址0x18 */  if (NewState != DISABLE)  {    RCC->APB2ENR |= RCC_APB2Periph; //打开对应的外设时钟输出口  }  else  {    RCC->APB2ENR &= ~RCC_APB2Periph;//关闭对应的外设时钟输出口  }}