網上大多數延時函式都是通過中斷方式的通用定時器來實現，如果實現1us的延時那麼每1us就來一次中斷，很影響cpu的效率。

本文不使用中斷通過是用通用定時器來實現精確延時。

程式碼如下（基於stm32f103）

static void udelay(uint32_t us)
{
	uint32_t count = us;

	TIM_SetCounter(TIM2, count);
	TIM_Cmd(TIM2, ENABLE);

	while (count > 1)//一般改為>= 1,只是 > 1延時偶爾會不夠
	{
		count = TIM_GetCounter(TIM2);
	}
	TIM_Cmd(TIM2, DISABLE);
}

static void TIM_Configuration(void)//2us
{
	TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;

	RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);

	TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1;
	TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Down;
	TIM_TimeBaseStructure.TIM_Period = 1;
	TIM_TimeBaseStructure.TIM_Prescaler = 71;//72Mhz
	TIM_TimeBaseStructure.TIM_RepetitionCounter = 0;

	TIM_TimeBaseInit(TIM2, &TIM_TimeBaseStructure);

	TIM_Cmd(TIM2, DISABLE);
}
 

示波器測試抓到的5us延時如下：