const int trigPin=5;
const int echoPin=18;
const int z1=12;
const int z2=13;
const int z3=14;
const int z4=15;

#define SOUND_SPEED 0.034
#define CM_TO_INCH 0.393701

long duration;
float distanceCm;
float distanceInch;

void setup(){
 Serial.begin(115200);
 pinMode(trigPin, OUTPUT);
 pinMode(echoPin, INPUT);
pinMode(z1, OUTPUT);
pinMode(z2, OUTPUT);
pinMode(z3, OUTPUT);
pinMode(z4, OUTPUT);


}

void loop(){
digitalWrite(trigPin, LOW);
delayMicroseconds(2);
digitalWrite(trigPin, HIGH);
delayMicroseconds(10);
digitalWrite(trigPin, LOW);

duration = pulseIn(echoPin,HIGH);
distanceCm = duration * SOUND_SPEED/2;
distanceInch = distanceCm * CM_TO_INCH;

Serial.print("Distance(cm): ");
Serial.println(distanceCm);
Serial.print("Distance(inch): ");
Serial.println(distanceInch);



digitalWrite(z1, LOW);
digitalWrite(z2, HIGH);
digitalWrite(z3, LOW);
digitalWrite(z4, HIGH);
delay(100);

if(distanceCm>=3 && distanceCm<=20){

digitalWrite(z1, HIGH);
digitalWrite(z2, LOW);
digitalWrite(z3, LOW);
digitalWrite(z4, LOW);
delay(3000);

}




}