#include <LiquidCrystal_I2C.h>

// Define the pins for the ultrasonic sensor
#define PIN_TRIG 12
#define PIN_ECHO 11

// Define the pins for the button and LEDs
const int buttonPin = 2;
const int merah = 10;  // Red LED
const int kuning = 9;  // Yellow LED
const int biru = 8;    // Blue LED
const int btn = 7;     // Button pin

// Variables to store the measured distance and echo time
float cm;
float temp;

// Initialize the LCD with I2C address 0x27 and size 20x4
LiquidCrystal_I2C lcd(0x27, 20, 4);

int displayState = 0; // Variable to track the current display state
unsigned long lastDebounceTime = 0; // the last time the output pin was toggled
unsigned long debounceDelay = 50; // the debounce time; increase if the output flickers

void setup() {
  // Start serial communication for debugging
  Serial.begin(9600);

  // Set the pin modes for the ultrasonic sensor
  pinMode(PIN_TRIG, OUTPUT);
  pinMode(PIN_ECHO, INPUT);

  // Initialize the LCD and turn on the backlight
  lcd.init();
  lcd.backlight();

  // Set the pin modes for the button and LEDs
  pinMode(buttonPin, INPUT_PULLUP);
  pinMode(merah, OUTPUT);
  pinMode(kuning, OUTPUT);
  pinMode(biru, OUTPUT);
  pinMode(btn, INPUT_PULLUP);  // Set button pin as input with pull-up resistor
}

void loop() {
  // Read the state of the button and handle debouncing
  int reading = digitalRead(btn);
  if (reading == LOW && (millis() - lastDebounceTime) > debounceDelay) {
    lastDebounceTime = millis();
    displayState = (displayState + 1) % 3; // Cycle through display states (0, 1, 2)
  }

  // Trigger the ultrasonic sensor
  digitalWrite(PIN_TRIG, LOW);
  delayMicroseconds(2);
  digitalWrite(PIN_TRIG, HIGH);
  delayMicroseconds(10);  // Ensure the TRIG pin is HIGH for 10 microseconds
  digitalWrite(PIN_TRIG, LOW);

  // Measure the duration of the echo signal
  temp = float(pulseIn(PIN_ECHO, HIGH));
  cm = (temp * 0.0343) / 2;  // Convert the echo time to distance in cm

  // Print the echo time and distance to the serial monitor
  Serial.print("Echo = ");
  Serial.print(temp);
  Serial.print(", Distance = ");
  Serial.print(cm);
  Serial.println(" cm");

  // Update the LCD based on the current display state
  lcd.clear();
  switch (displayState) {
    case 0:
      lcd.setCursor(0, 0);
      lcd.print("Echo =");
      lcd.print(temp);
      lcd.setCursor(0, 1);
      lcd.print("Distance=");
      lcd.print(cm);
      lcd.print(" cm");
      break;
    case 1:
      lcd.setCursor(0, 0);
      lcd.print("Distance=");
      lcd.print(cm);
      lcd.print(" cm");
      lcd.setCursor(0, 1);
      lcd.print("Button: ");
      if (reading == LOW) {
        lcd.print("ON");
      } else {
        lcd.print("OFF");
      }
      break;
    case 2:
      lcd.setCursor(0, 0);
      lcd.print("Temp=");
      lcd.print(temp);
      lcd.print(" us");
      lcd.setCursor(0, 1);
      lcd.print("Press btn to toggle");
      break;
  }

  // Light up LEDs based on the measured distance
  if (cm <= 100) {
    digitalWrite(merah, HIGH); 
    digitalWrite(kuning, LOW);
    digitalWrite(biru, LOW);
  } else if (cm <= 200) {
    digitalWrite(merah, LOW); 
    digitalWrite(kuning, HIGH);
    digitalWrite(biru, LOW);
  } else {
    digitalWrite(merah, HIGH);
    digitalWrite(kuning, HIGH);
    digitalWrite(biru, HIGH);
  }

  // Wait for 200 milliseconds before the next loop iteration
  delay(200);
}