const int trigPin = 5;
const int echoPin = 18;

//define sound speed in cm/uS
#define SOUND_SPEED 0.034

long duration;
float distanceCm;

void setup() {
  Serial.begin(115200); 
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT); 
}

void loop() {
    digitalWrite(trigPin, LOW);
     digitalWrite(trigPin, HIGH);
    digitalWrite(trigPin, LOW);
  
  
  duration = pulseIn(echoPin, HIGH);
  
  
  distanceCm = duration * SOUND_SPEED/2;
   
  Serial.print("Distance (cm): ");
  Serial.println(distanceCm);
   
  delay(1000);
}