#include <LiquidCrystal_I2C.h>
LiquidCrystal_I2C lcd(0x27, 16, 2);
const int TRIG_PIN  = 2;  // Arduino pin connected to Ultrasonic Sensor's TRIG pin
const int ECHO_PIN  = 3;  // Arduino pin connected to Ultrasonic Sensor's ECHO pin
//const int RELAY_PIN = 8; // Arduino pin connected to Relay's pin
const int DISTANCE_THRESHOLD = 50; // centimeters
const int buzzer = 8;
const int led1 = 6;
const int led2 = 5;


// variables will change:
float waktu, jarak_cm;

void setup() {
  lcd.init();
  lcd.backlight();
  Serial.begin (9600);        // initialize serial port
  pinMode(TRIG_PIN, OUTPUT);  // set arduino pin to output mode
  pinMode(ECHO_PIN, INPUT);   // set arduino pin to input mode
  //pinMode(RELAY_PIN, OUTPUT); // set arduino pin to output mode
  pinMode(buzzer, OUTPUT);
  pinMode(led1, OUTPUT);
  pinMode(led2, OUTPUT);
}

void loop() {
  // generate 10-microsecond pulse to TRIG pin
  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);

  // measure duration of pulse from ECHO pin
  waktu = pulseIn(ECHO_PIN, HIGH);
  // calculate the distance
  jarak_cm = 0.017 * waktu;

  if(jarak_cm < DISTANCE_THRESHOLD){
    //digitalWrite(RELAY_PIN, HIGH); // turn on Relay
    digitalWrite(buzzer, LOW);
    digitalWrite(led1, HIGH);
    digitalWrite(led2, LOW);
    delay(200);
    digitalWrite(led1, LOW);
    digitalWrite(led2, HIGH);
    delay(200);
    lcd1();
  }
  else{
    //digitalWrite(RELAY_PIN, LOW);  // turn off Relay
    digitalWrite(led1, LOW);
    digitalWrite(led2, LOW);
    digitalWrite(buzzer, HIGH);
    delay(100);
    digitalWrite(buzzer, LOW);
    delay(100);
    lcd2();
    
  }
  // print the value to Serial Monitor
}


void lcd1(){
  lcd.clear();
    lcd.setCursor(0, 0);
    lcd.print("Jarak: ");
    lcd.setCursor(7, 0);
    lcd.print(jarak_cm);
    lcd.setCursor(14, 0);
    lcd.print("cm");
    lcd.setCursor(0, 1);
    lcd.print("Aman Bro");
    Serial.print("jarak: ");
    Serial.print(jarak_cm);
    Serial.println(" cm");
    Serial.println("Aman");
    Serial.println(" ");
    delay(100);
}


void lcd2(){
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Jarak: ");
  lcd.setCursor(7, 0);
  lcd.print(jarak_cm);
  lcd.setCursor(14, 0);
  lcd.print("cm");
  lcd.setCursor(0, 1);
  lcd.print("Bahaya Cok");
  Serial.print("jarak: ");
  Serial.print(jarak_cm);
  Serial.println(" cm");
  Serial.println("Bahaya");
  Serial.println(" ");
  delay(100);
}