int trigPin = 7;
int echoPin = 6;
float duration_us, distance_cm;

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

void loop() {
  digitalWrite(trigPin, HIGH);
  delay(10);
  digitalWrite(trigPin, LOW);
  duration_us = pulseIn(echoPin, HIGH);
  distance_cm = 0.017 * duration_us;
  Serial.println("distance = ");
  Serial.print(distance_cm);
  Serial.println("cm");
  delay(1000);
}