int trigPin=9;
int echoPin=10;
float duration_us,distance_cm;
void setup() {
  // put your setup code here, to run once:
Serial.begin(9600);
pinMode(trigPin, OUTPUT);
pinMode(echoPin, INPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
digitalWrite(trigPin, HIGH);
delayMicroseconds(10);
digitalWrite(trigPin, LOW);
duration_us=pulseIn(echoPin,HIGH);
distance_cm=0.017*duration_us;
Serial.print("distance");
Serial.print(distance_cm);
Serial.println("cm");
delay(500);
}