1：processing
2：arduino代码，自己稍改了一下
const int TrigPin = 3;
const int EchoPin = 4;

float SR04cm;
float m;
float dis=0;
float dis2=0;
float SR04()
{
      digitalWrite
      (TrigPin, LOW);
      delayMicroseconds(2);  
      digitalWrite(TrigPin, HIGH);
      delayMicroseconds(12);
      digitalWrite(TrigPin, LOW);  
      SR04cm = pulseIn(EchoPin, HIGH) / 58.00; //算成厘米 //
      SR04cm = (int(m * 100.0)) / 100.0; //保留两位小数
      delayMicroseconds(2);return SR04cm;}
void setup()
{
      Serial.begin(9600);  
      pinMode(TrigPin, OUTPUT);
      pinMode(EchoPin, INPUT);
}
void loop()
{
      int echocm=SR04();
      Serial.println(echocm);
      delay(10);
}

processing代码，没改过

import processing.serial.*;
Serial myPort=new Serial(this, Serial.list()[1], 9600);

float r=250;
float a=0;
float x, y;
void setup()
{  
     size(600, 600);  
     background(0);  
     smooth();  
     stroke(255);  
     frameRate(100);  
     println(Serial.list());
}
void draw()
{  
     displayX();  
     displayY();  
     fill(0,3);  
     noStroke();  
     rect(0, 0, width, height);  
     x=r*cos(a);  
     y=r*sin(a);  
     if (myPort.available()>0)
     {    
         int data;    
         data=myPort.read();      
         fill(255);    
         text("DISTANCE:", 30, 50);    
         text(data, 100, 50);    
         stroke(0, 200, 0);    
         strokeWeight(4);    
         line(width/2, height/2, width/2+x, height/2+y);//步进电机转一下，扫描线转一下    
         a=a+0.0124;//弧度增加    
         if (data<=50)
         {      
            stroke(255, 0, 0);      
            strokeWeight(10);      
            float locx, locy;      
            locx=5*(data-1)*cos(a);      
            locy=5*(data-1)*sin(a);      
            point(width/2+locx, height/2+locy);    
          }  
      }
}
void displayX()
{  
     for (int i=-250;i<300;i+=50)
     {    
         fill(255);    
         if (i<=0)      
           text(i, i+300, 300);    
         else      
           text(i, i+285, 300);  
      }
}
void displayY()
{  
      for (int i=250;i>=-250;i-=50)
      {    
          if (i!=0)
          {      
              fill(255);      
              text(i, 300, 300-i);    
           }  
       }
}
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