#include <LiquidCrystal_I2C.h>
LiquidCrystal_I2C lcd(0x27, 16,2);
#define trigPin  A0
#define echoPin A1
int ledhijau = 9; 
int Buzzer = 7; 
int ledmerah = 8; 

int duration, distance; 
void setup() {
        Serial.begin (9600); 
        lcd.init();
  lcd.backlight();
  lcd.home();
        pinMode(trigPin, OUTPUT); 
        pinMode(echoPin, INPUT);
        pinMode(Buzzer, OUTPUT);
        pinMode(ledmerah, OUTPUT);
        pinMode(ledhijau, OUTPUT);
}
void loop() {
      lcd.clear();
    digitalWrite(trigPin, HIGH);
    delayMicroseconds(10);
    digitalWrite(trigPin, LOW);
    duration = pulseIn(echoPin, HIGH);
    distance = (duration/2) / 29.1;
    Serial.println(distance);
  if (distance <= 10 ) 
        {
       // Serial.println("object detected \n");
        //Serial.print("distance= ");
        lcd.setCursor(0,0);
      lcd.print("ada benda");              
        Serial.print(distance);        //mendeteksi jarak jika berada di antara kisaran 0 hingga 200
        digitalWrite (ledhijau,LOW);
        digitalWrite (ledmerah,HIGH);
        tone(Buzzer,900); 
        delay (500);   
        digitalWrite (ledmerah,LOW);
        tone(Buzzer,500);     
        delay (500); 
        }
  else {
     //  Serial.println("no object detected");
     lcd.setCursor(0,0);
      lcd.print("tidak ada benda");
        noTone(Buzzer);
        digitalWrite (ledhijau,HIGH);
        digitalWrite (ledmerah,LOW);      
  }
}