#include <LiquidCrystal.h>

const int rs = 12, en = 11, d4 = 5, d5 = 4, d6 = 3, d7 = 2;
LiquidCrystal lcd(rs,en,d4,d5,d6,d7);

const int trigPin = 8;
const int echoPin = 9;
const int buzzer = 13;
long duration;

int distanceCm;
int maxDistance = 100;

int redLEDPin = 10;
int greenLEDPin = 6;
int blueLEDPin = 7;

int red = 0;
int blue = 0;
int green = 0;




void setup()
{  
  	lcd.begin(16,2);
  	pinMode(trigPin, OUTPUT);
  	pinMode(echoPin, INPUT);
    pinMode(redLEDPin, OUTPUT);
  	pinMode(greenLEDPin, OUTPUT);
 	pinMode(blueLEDPin, OUTPUT);  
}

void loop()
{
  //Initialization of Ultrasonic sensor and distance calculation.
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);
  duration = pulseIn(echoPin, HIGH);
  distanceCm = duration * 0.034 / 2;
  // RGB LED changes color from green to red if the distance is lower than 25.
  	if(distanceCm<25)
  	{	
    	green=0;
    	red=255;
  	}
  	else
  	{	
    	red=0;
    	green=255;
  	}
  
  analogWrite(redLEDPin, red);
  analogWrite(greenLEDPin, green);
  analogWrite(blueLEDPin, blue);
  delay(10);
    
 //Buzzer tones at different distances
    if(distanceCm < 10)
  	{
    	tone(buzzer,480);
    	delay(15);
    	noTone(buzzer);
    }
  
    else if(distanceCm <= 20)
  	{
    	tone(buzzer,480);
    	delay(50);
    	noTone(buzzer);
    }
    else if(distanceCm <= 30)
  	{
    	tone(buzzer,480);
    	delay(100);
    	noTone(buzzer);
  
    }

  //Display values to LCD
  
  lcd.setCursor(0,0);
  delay(150);
  
  if(distanceCm>maxDistance)
  	{
    	distanceCm = 0;
  	}
  lcd.print("Distance: ");
  lcd.setCursor(10,0);
  
  if(distanceCm != 0)
  	{
  		lcd.print(distanceCm);
  		lcd.println(" cm    ");
  	}
  else
 	{
    	lcd.print("---   ");
  	}
  lcd.setCursor(0,1);
  lcd.print("Max dist: ");
  lcd.print(maxDistance);
  lcd.print(" cm  ");
   
  delay(10);
  
}