#include <Wire.h>
#include <LiquidCrystal_I2C.h>

LiquidCrystal_I2C lcd(0x27, 16, 2);

#define PT 4
#define PE 3
const int relayPin = 2;

long duration = 0;

void setup() {
  Serial.begin(9600 );
  pinMode(PT, OUTPUT );
  pinMode(PE, INPUT );
  pinMode(relayPin, OUTPUT);


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

void loop() {
  digitalWrite(PT, HIGH );
  delay(10 );
  digitalWrite(PT, LOW );
  int dur = pulseIn(PE, HIGH );
  int dis = dur / 58.5 ;
  Serial.print("Distance in CM: ");
  Serial.println(dur / 58.5  ); // duration % 58 = distance in cm 


    lcd.clear();
    lcd.setCursor(0, 0);
    lcd.print("Distance: ");
    lcd.print(dis);
    lcd.print(" cm");
    if (dis < 30) {
        digitalWrite(relayPin, HIGH);
        lcd.setCursor(0, 1);
        lcd.print("Fast Switching");
        delay(20);
    } 
    else if (dis >= 30 && dis < 60) {
        digitalWrite(relayPin, HIGH);
        lcd.setCursor(0, 1);
        lcd.print("Medium Switching");
        delay(50);
    } 
    else if (dis >= 60 && dis <= 100) {
        digitalWrite(relayPin, HIGH);
        lcd.setCursor(0, 1);
        lcd.print("Slow Switching");
        delay(100);
    } 
    else {
        digitalWrite(relayPin, LOW);
        lcd.setCursor(0, 1);
        lcd.print("Out of Range");
    }

    delay(100);
}