sensor HC-SR04

  int trigPin2  = 2 ;
  int echoPin2 = 3 ;
  int trigPin1  = 4 ;
  int echoPin1 = 5 ;
 
 
  int revright = 8 ;       //REVerse motion of Left motor
  int fwdleft = 9 ;       //ForWarD motion of Left motor
  int revleft = 10 ;      //REVerse motion of Right motor
  int fwdright = 11 ;
  int duration = pulseIn( echoPin2, HIGH );
  int distance = (duration * 0.0343) / 2;


 
  void setup() {
  pinMode(8, OUTPUT);
  pinMode(9, OUTPUT);
  pinMode(10, OUTPUT);
  pinMode(11, OUTPUT);
  pinMode(trigPin1, OUTPUT);
  pinMode(echoPin1, INPUT );
  pinMode(trigPin2, OUTPUT);
  pinMode(echoPin2, INPUT );
  


 
      Serial.begin(9600);
}
 
      void loop() {
      digitalWrite(trigPin2, LOW);
      delayMicroseconds(2);
      digitalWrite(trigPin2, HIGH);
      delayMicroseconds(10);
      digitalWrite(trigPin2, LOW);
      duration = pulseIn(echoPin2, HIGH);
      distance = (duration * 0.0343) / 2;
      
      digitalWrite(trigPin1, LOW);
      delayMicroseconds(2);
      digitalWrite(trigPin1, HIGH);
      delayMicroseconds(10);
      digitalWrite(trigPin1, LOW);
      duration = pulseIn(echoPin1, HIGH);
      distance = (duration * 0.0343) / 2;
      
          if (distance < 30){ 
  
     digitalWrite(8,  LOW);
     digitalWrite(9,  LOW);
     digitalWrite(10,  LOW);
     digitalWrite(11,  LOW);
     delay(1000);


        
     digitalWrite(8, LOW);
     digitalWrite(9, HIGH);
     digitalWrite(10, LOW);
     digitalWrite(11, HIGH);
     delay(500);
      
     digitalWrite(8, LOW); 
     digitalWrite(9, LOW);
     digitalWrite(10, LOW);
     digitalWrite(11, LOW);
     delay(2000);


  
     digitalWrite(8, LOW );
     digitalWrite(9, LOW );
     digitalWrite(10, LOW );
     digitalWrite(11, HIGH );
     delay(500);
  

     digitalWrite(8,  LOW);
     digitalWrite(9,  LOW);
     digitalWrite(10,  LOW);
     digitalWrite(11,  LOW);
    delay(1000); 
    
          } else { 
  digitalWrite(8, HIGH);
  digitalWrite(9, LOW);
  digitalWrite(10, HIGH);
  digitalWrite(11, LOW);
          }}