#include <LiquidCrystal_I2C.h>
#define piezoPin 3
#define trigPin 9
#define echoPin 10
#define redPin 11
#define greenPin 12
#define bluePin 13

LiquidCrystal_I2C lcd(0x27, 16, 2);

void setup() {
  pinMode(piezoPin, OUTPUT);
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  
  pinMode(redPin, OUTPUT);
  pinMode(greenPin, OUTPUT);
  pinMode(bluePin, OUTPUT);

  lcd.init(); 
  lcd.backlight();
} 

void loop() {
  long duration, distance;
  
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);
  
  duration = pulseIn(echoPin, HIGH);
  
  distance = duration * 0.034 / 2;

  lcd.clear();
  lcd.setCursor(0,0);
  lcd.print("Dist: ");
  lcd.print(distance);
  lcd.print(" cm");

  float distanceInInches = distance / 2.54;
  
  lcd.setCursor(0,1);
  lcd.print("Dist: ");
  lcd.print(distanceInInches);
  lcd.print(" in");

  if (distance > 100) {
    tone(piezoPin, 600); 
    delay(1000);
    noTone(piezoPin);
  }

  if (distance < 30) {
    digitalWrite(greenPin, HIGH);
    digitalWrite(redPin, LOW);
    digitalWrite(bluePin, LOW);
  } else if (distance >= 30 && distance < 70) {
    digitalWrite(redPin, LOW);   
    digitalWrite(greenPin, HIGH); 
    digitalWrite(bluePin, LOW);
  } else {
    digitalWrite(redPin, HIGH); 
    digitalWrite(greenPin, LOW);
    digitalWrite(bluePin, LOW);
  }

  delay(500); 
}