/*
 HC-SR04 Ultrasonic Distance Sensor
 CODED BY: Nitish Dash [nitishdash95@gmail.com]
 More info at: http://eweekend.blogspot.com
 */

#define trig 13
#define echo 12
#define red 11
#define green 10

void setup() {
  Serial.begin (9600);
  pinMode(trig, OUTPUT);
  pinMode(echo, INPUT);
  pinMode(red, OUTPUT);
  pinMode(green, OUTPUT);
}

void loop() {
  long time, dist;
  digitalWrite(trig, LOW); 
  delayMicroseconds(2); 
  digitalWrite(trig, HIGH);
  delayMicroseconds(10); 
  digitalWrite(trig, LOW);
  time = pulseIn(echo, HIGH);
  dist = ((time/2) / 29.1); //measure in cms
  if (dist < 12) //change this to set proximity distance 
  
{  
    digitalWrite(red,HIGH); 
  digitalWrite(green,LOW);
}
  else {
    digitalWrite(red,LOW);
    digitalWrite(green,HIGH);
  }
  if (dist >= 200 || dist <= 0){
    Serial.println("Out of range");
  }
  else {
    Serial.print(dist);
    Serial.println(" cm");
  }
  delay(400);
}