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
   pinMode(13, OUTPUT);
   pinMode(12, OUTPUT);
}

void loop() {
   bool hall = 0;
   bool king = 0;
   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);
   cm = microsecondsToCentimeters(duration);
   if(cm > 10)
   {
    digitalWrite(13, HIGH);
    digitalWrite(12, LOW);
   }
   if(cm <= 10)
   {
    digitalWrite(13, LOW);
    digitalWrite(12, HIGH);
   }
   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;
}