#define  ECHO_PIN 3 // pin echo pin 3
#define  TRIG_PIN 2 // trig pin 2 ke pin 2
#define pinBuzzer 5 // pin buzzer  ke 5

#include <Servo.h> // library servo
Servo myservo;
int rotasi = 90;
int interval = 0;

float readDistanceCM(){
  // program trigger memancarkan ultrasonic
  digitalWrite(TRIG_PIN, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);

  //durasi adalah waktu tunngi pin Echo bernilai HIGH
  //setelah mendapat pantulan gelombang ultrasonic dari pin Trigger
  int duration = pulseIn(ECHO_PIN, HIGH);
  return duration * 0.034/2; //konversi nilai durasi ke jarak
}

void soundBuzzer(){
  if(interval < 500){
    tone(pinBuzzer, 250);
  }else
  if(interval > 500){
    tone(pinBuzzer, 100,800);
  };
}

void setup() {
  pinMode(TRIG_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);
  pinMode(13, OUTPUT);
  Serial.begin(115200);// kecepatan komunikasi serial dengan komputer
  pinMode(pinBuzzer, OUTPUT);
  
  myservo.attach(9); //pin pwm ke pin 9 
  myservo.write(90);
}

void loop() {
 tutupPalang();
 interval +=100;
 if(interval>1000) interval = 0;
}

void tutupPalang(){
  float jarak = readDistanceCM();
  if(jarak > 0 && jarak < 100 ){
    soundBuzzer();
    tutup();
    digitalWrite(13, HIGH);
  }else{
    buka();
    noTone(pinBuzzer);
    digitalWrite(13, LOW);
    
  }
}

void tutup(){
  if(rotasi <= 90){
    myservo.write(rotasi);
    delay(100);
    rotasi--;
  }
  if(rotasi <= 0 ) rotasi = 0;
}

void buka(){
  if(rotasi <= 90){
    myservo.write(rotasi);
    delay(100);
    rotasi+=4;
  }
  if(rotasi >= 90 ) rotasi = 90;
}