STM32驅動超聲波測距傳感器

先貼代碼，以後再補說明

TIM_ICInitTypeDef  TIM5_ICInitStructure;

void TIM5_Cap_Init(u16 arr,u16 psc)
{	 
	GPIO_InitTypeDef GPIO_InitStructure;
	TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;
   	NVIC_InitTypeDef NVIC_InitStructure;

	RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM5, ENABLE);	//使能TIM5時鐘
 	RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE);  //使能GPIOA時鐘
	
	GPIO_InitStructure.GPIO_Pin  = GPIO_Pin_0;  //PA0 清除之前設置  
	GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IPD; //PA0 輸入  
	GPIO_Init(GPIOA, &GPIO_InitStructure);
	GPIO_ResetBits(GPIOA,GPIO_Pin_0);						 //PA0 下拉
	
	//初始化定時器5 TIM5	 
	TIM_TimeBaseStructure.TIM_Period = arr; //設定計數器自動重裝值 
	TIM_TimeBaseStructure.TIM_Prescaler =psc; 	//預分頻器   
	TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1; //設置時鐘分割:TDTS = Tck_tim
	TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;  //TIM向上計數模式
	TIM_TimeBaseInit(TIM5, &TIM_TimeBaseStructure); //根據TIM_TimeBaseInitStruct中指定的參數初始化TIMx的時間基數單位
  
	//初始化TIM5輸入捕獲參數
	TIM5_ICInitStructure.TIM_Channel = TIM_Channel_1; //CC1S=01 	選擇輸入端 IC1映射到TI1上
  	TIM5_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_Rising;	//上升沿捕獲
  	TIM5_ICInitStructure.TIM_ICSelection = TIM_ICSelection_DirectTI; //映射到TI1上
  	TIM5_ICInitStructure.TIM_ICPrescaler = TIM_ICPSC_DIV1;	 //配置輸入分頻,不分頻 
  	TIM5_ICInitStructure.TIM_ICFilter = 0x00;//IC1F=0000 配置輸入濾波器 不濾波
  	TIM_ICInit(TIM5, &TIM5_ICInitStructure);
	
	//中斷分組初始化
	NVIC_InitStructure.NVIC_IRQChannel = TIM5_IRQn;  //TIM3中斷
	NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 2;  //先佔優先級2級
	NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;  //從優先級0級
	NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE; //IRQ通道被使能
	NVIC_Init(&NVIC_InitStructure);  //根據NVIC_InitStruct中指定的參數初始化外設NVIC寄存器 
	
	TIM_ITConfig(TIM5,TIM_IT_Update|TIM_IT_CC1,ENABLE);//允許更新中斷 ,允許CC1IE捕獲中斷	
	
   	TIM_Cmd(TIM5,ENABLE ); 	//使能定時器5
   


}

u8  TIM5CH1_CAPTURE_STA=0;	//輸入捕獲狀態		    				
u16	TIM5CH1_CAPTURE_VAL;	//輸入捕獲值
 
//定時器5中斷服務程序	 
void TIM5_IRQHandler(void)
{ 

 	if((TIM5CH1_CAPTURE_STA&0X80)==0)//還未成功捕獲	
	{	  
		if (TIM_GetITStatus(TIM5, TIM_IT_Update) != RESET)
		 
		{	    
			if(TIM5CH1_CAPTURE_STA&0X40)//已經捕獲到高電平了
			{
				if((TIM5CH1_CAPTURE_STA&0X3F)==0X3F)//高電平太長了
				{
					TIM5CH1_CAPTURE_STA|=0X80;//標記成功捕獲了一次
					TIM5CH1_CAPTURE_VAL=0XFFFF;
				}else TIM5CH1_CAPTURE_STA++;
			}	 
		}
	if (TIM_GetITStatus(TIM5, TIM_IT_CC1) != RESET)//捕獲1發生捕獲事件
		{	
			if(TIM5CH1_CAPTURE_STA&0X40)		//捕獲到一個下降沿 		
			{	  			
				TIM5CH1_CAPTURE_STA|=0X80;		//標記成功捕獲到一次高電平脈寬
				TIM5CH1_CAPTURE_VAL=TIM_GetCapture1(TIM5);
		   		TIM_OC1PolarityConfig(TIM5,TIM_ICPolarity_Rising); //CC1P=0 設置爲上升沿捕獲
			}else  								//還未開始,第一次捕獲上升沿
			{
				TIM5CH1_CAPTURE_STA=0;			//清空
				TIM5CH1_CAPTURE_VAL=0;
	 			TIM_SetCounter(TIM5,0);
				TIM5CH1_CAPTURE_STA|=0X40;		//標記捕獲到了上升沿
		   		TIM_OC1PolarityConfig(TIM5,TIM_ICPolarity_Falling);		//CC1P=1 設置爲下降沿捕獲
			}		    
		}			     	    					   
 	}
 
    TIM_ClearITPendingBit(TIM5, TIM_IT_CC1|TIM_IT_Update); //清除中斷標誌位
 
}

主函數調用如下：

TIM5_Cap_Init(0XFFFF,72-1);	//以1Mhz的頻率計數 
if(TIM5CH1_CAPTURE_STA&0X80)//成功捕獲到了一次上升沿
		{
			temp=TIM5CH1_CAPTURE_STA&0X3F;
			temp*=65536;//溢出時間總和
			temp+=TIM5CH1_CAPTURE_VAL;//得到總的高電平時間
			printf("HIGH:%d us,\tLength: %.3f m\r\n",temp,((float)temp*346/1000/1000/2));//打印總的高點平時間
			TIM5CH1_CAPTURE_STA=0;//開啓下一次捕獲
		}

打印Log直接輸出採樣到的高電平時間和目標到傳感器的直線距離。