const int trigPin = 9;
const int echoPin = 8;

void setup() {
  Serial.begin(9600);
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
}

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

  float duration = pulseIn(echoPin, HIGH);

  float distance = (duration * 0.0343 ) / 2;

  Serial.print("distance: ");
  Serial.print(distance);
  Serial.println(" cm");
}