int trigPin = 9;
int echoPin = 8;

long duration, cm, inches;

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, LOW);
  delayMicroseconds(5);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  // read singal
  pinMode(echoPin, INPUT);
  duration=pulseIn(echoPin, HIGH);

  //convert distance
  cm = (duration/2) / 29.1;
  inches = (duration/2) / 74;


  Serial.print(inches);
  Serial.print("in, ");
  Serial.print(cm);
  Serial.print("cm, ");
  Serial.println();
  delay(1000);
}