ardunio 实验：超声波测距、声光报警模拟倒车雷达

所用元件：

     1、Arduino 2012 UNO R3开发板
     2、超声波模块：HC-SR04
     3、LED \ 蜂鸣器

功能：

• 输出测距信息至串口
• 距离20CM 蜂鸣器开始报警，LED闪烁
• 20CM 到 3CM 间 报警音不断急促，3CM内报警音长鸣，LED长亮

代码：

int beeppin = 8;
int ledpin=9;
int echo= 6;
int trig=7;
unsigned long time_echo=0; // record the pulse width by sensor returns
unsigned long distance =0; // record the distance value;
 
void setup(){
   Serial.begin(9600);
   pinMode(beeppin,OUTPUT);
   pinMode(ledpin,OUTPUT);   
   pinMode(echo,INPUT);
   pinMode(trig,OUTPUT);
}
 
void loop(){
  digitalWrite(trig,HIGH);  //send pulse
  delayMicroseconds(80);    //set pulse width with 50us(>10us)
  digitalWrite(trig,LOW);   //stop send
 
  time_echo = pulseIn(echo,HIGH); //get return pulse width
  if((time_echo<60000)&&(time_echo>1)) //valid scope 1-60000
  {
    distance = (time_echo*34/100)/2; //mm   
    if(distance < 200)
     {
      if(distance<30){
        digitalWrite(beeppin,HIGH);
        digitalWrite(ledpin,HIGH);
      }else{   
        alert(distance/2);
      }
     }
    Serial.print(distance,DEC);
    Serial.println('\n');
 
  }
  delay(100);
}
void alert(unsigned i){
  digitalWrite(beeppin,HIGH);
  digitalWrite(ledpin,HIGH);
  delay(i);
  digitalWrite(beeppin,LOW);
  digitalWrite(ledpin,LOW);
  delay(i);
}