/*
 HC-SR04 Ping distance sensor
 VCC to arduino 5v GND to arduino GND
 Echo to Arduino pin 9 Trig to Arduino pin 8
 Buzzer +ve to Arduino pin 13 and GND to GND
 Original code sourced from theorycircuit.com
 Some code and wiring inspired by arduino.cc
 */

#define trigPin 8
#define echoPin 9
#define Buzzer 13


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

void loop() {
  
  digitalWrite(trigPin, LOW);  
  delayMicroseconds(2); 
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10); 
  digitalWrite(trigPin, LOW);

  duration = pulseIn(echoPin, HIGH);

  distance = (duration/2) / 29.1;

  if (distance < 30) 
   {  

    digitalWrite(Buzzer,HIGH); // When the Red condition is met, the Green LED should turn off
    
    }
  else {
    digitalWrite(Buzzer,LOW);
        }


  if (distance >= 200 || distance <= 0)
  {
    Serial.println("Out of range");
  }
  else {
    Serial.print(distance);
    Serial.println(" cm");
       }
  delay(500);
}