#include <LiquidCrystal.h> 

LiquidCrystal lcd(13, 7, 9, 8, 10, 11);
const int trigPin = 12;
const int echoPin = 6;
long duration;
int distanceCm, distanceInch;
int GREEN = 4;
int YELLOW = 3;
int RED = 2;
int DELAY_GREEN = 5000;
int DELAY_YELLOW = 2000;
int DELAY_RED = 5000;


void setup() { 
lcd.begin(16,2); 
pinMode(trigPin, OUTPUT);
pinMode(echoPin, INPUT);
pinMode(GREEN, OUTPUT);
pinMode(YELLOW, OUTPUT);
pinMode(RED, OUTPUT);

}

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

  duration = pulseIn(echoPin, HIGH);
  distanceCm= duration*0.034/2;
  distanceInch = duration*0.0133/2;

lcd.setCursor(0,0); 
lcd.print("Distance: "); 
lcd.print(distanceCm); 
lcd.print("  cm");
delay(10);
lcd.setCursor(0,1);
lcd.print("Distance: ");
lcd.print(distanceInch);
lcd.print("inch");
delay(10);
  
green_light();
delay(DELAY_GREEN);
yellow_light();
delay(DELAY_YELLOW);
red_light();
delay(DELAY_RED);
}

void green_light()
{
  digitalWrite(GREEN, HIGH);
  digitalWrite(YELLOW, LOW);
  digitalWrite(RED, LOW);
}

void yellow_light()
{
  digitalWrite(GREEN, LOW);
  digitalWrite(YELLOW, HIGH);
  digitalWrite(RED, LOW);
}

void red_light()
{
  digitalWrite(GREEN, LOW);
  digitalWrite(YELLOW, LOW);
  digitalWrite(RED, HIGH);
}