const int pingPin = 7; // trigger pin of ultrasonic sensor
const int echoPin = 6; // echo pin of ultrasonic sensor
void setup() {
  Serial.begin(9600); // starting serial terminal
}

void loop() {
  long duration, inches, cm;
  pinMode(pingPin, OUTPUT);
  digitalWrite(pingPin, LOW);
  delayMicroseconds(2);
  digitalWrite(pingPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(pingPin, LOW);
  pinMode(echoPin, INPUT);
  duration = pulseIn(echoPin, HIGH);
  inches = microsecondsToInches (duration);
  cm = microsecondsToCentimeters (duration);
  Serial.print(inches);
  Serial.print("in, ");
  Serial.print(cm);
  Serial.print("cm, ");.,
  Serial.println();
  delay(100);
}

long microsecondsToInches (long microseconds) {
  return microseconds / 74 / 2;
  }
long microsecondsToCentimeters (long microseconds) {
  return microseconds / 29 / 2;
}