//library LCD I2C
#include <LiquidCrystal_I2C.h>

LiquidCrystal_I2C lcd (0x27,16,2);

//mendefinisikan dari sensor jarak
const int TRIG_PIN = 2;
const int ECHO_PIN = 3;
long echotime;

//mendefinisikan led merah
int led = 4;

//mendefinisikan switch
int saklar = 5;

//menyimpan data jarak
float jarak = 0;

void setup() 
{
  Serial.begin(9600);
  lcd.begin(16, 2);
  pinMode(TRIG_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);
  digitalWrite(TRIG_PIN, LOW);

  pinMode(led, OUTPUT);
  pinMode(saklar, INPUT);

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

void loop() 
{
  //jika saklar keadaan hidup
  if (digitalRead(saklar) == HIGH) {
    Aktif();
  }
  //jika saklar keadaan mati
  else {
    NonAktif();
  }
}

void NonAktif() 
{
  //keadaan saklar mati/belum nyala
  digitalWrite(led, LOW);
  
  lcd.clear();
  lcd.setCursor(3, 0);
  lcd.print("Meteran");
  lcd.setCursor(3, 1);
  lcd.print("Laser");
  delay(1000);
}

void Aktif() 
{
  //keadaan saklar hidup/nyala
  //led merah hidup
  digitalWrite(led, HIGH);
  
  //sensor ultrasonic menyala
  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);
  
  echotime = pulseIn(ECHO_PIN, HIGH);
  jarak = 0.0001 * ((float)echotime * 340.0 / 2.0); // perbaikan pada rumus jarak
  
  //menampilkan jarak di serial monitor
  Serial.print("Jarak: ");
  Serial.print(jarak);
  Serial.println(" cm");
  
  //menyalakan lcd I2C
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Jarak: ");
  lcd.print(jarak);
  lcd.print(" cm");
  delay(1000);
}