#include <LiquidCrystal.h>

// LCD pins: RS, EN, D4, D5, D6, D7
LiquidCrystal lcd(7, 8, 4, 5, 6, 9);

// Pins
const int trigPin = 12;
const int echoPin = 11;
const int ledPin = 13;
const int buttonMicro = 2;  // micros() button
const int buttonMilli = 3;  // millis() button

void setup() {
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  pinMode(ledPin, OUTPUT);
  pinMode(buttonMicro, INPUT_PULLUP);
  pinMode(buttonMilli, INPUT_PULLUP);

  lcd.begin(16, 2);

  // Line 1: Always display Prof.Tamer
  lcd.setCursor(0, 0);
  lcd.print("Prof.Tamer      ");
}

void loop() {
  long duration;
  float distance;

  // Trigger ultrasonic sensor
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  // Read echo pulse
  duration = pulseIn(echoPin, HIGH);
  distance = duration * 0.034 / 2;  // Convert to cm

  // Control LED based on distance
  digitalWrite(ledPin, (distance <= 19) ? HIGH : LOW);

  // Show time when buttons are pressed
  if (digitalRead(buttonMicro) == LOW) {
    lcd.setCursor(0, 1);
    lcd.print("Time(us):       ");
    lcd.setCursor(10, 1);
    lcd.print(micros());
  }
  else if (digitalRead(buttonMilli) == LOW) {
    lcd.setCursor(0, 1);
    lcd.print("Time(ms):       ");
    lcd.setCursor(10, 1);
    lcd.print(millis());
  }
  else {
    // Default display: Distance
    lcd.setCursor(0, 1);
    lcd.print("Distance:       ");
    lcd.setCursor(10, 1);
    lcd.print("     ");  // Clear old numbers
    lcd.setCursor(10, 1);
    lcd.print(distance, 1);
    lcd.print("cm");
  }

  delay(200);  // Sensor refresh delay
}