#define  PIN_ECHO 8
#define  PIN_TRIG 7
#define pinBuzzer 13

#include <Servo.h>

Servo myservo;
int rotasi = 90;
int interval = 0;

float readDistanceCM(){
  digitalWrite(PIN_TRIG, LOW);
  delayMicroseconds(2);
  digitalWrite(PIN_TRIG, HIGH);
  delayMicroseconds(10);
  digitalWrite(PIN_TRIG, LOW);
  int duration = pulseIn(PIN_ECHO, HIGH);
  return duration * 0.034/2;
}

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

void setup() {
  pinMode(PIN_TRIG, OUTPUT);
  pinMode(PIN_ECHO, INPUT);
  Serial.begin(115200);
  pinMode(pinBuzzer, OUTPUT);
  myservo.attach(9);
  myservo.write(90);
}

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

void tutupPalang(){
  float jarak = readDistanceCM();
  if(jarak > 0 && jarak < 50 ){
    soundBuzzer();
    tutup();
  }else{
    buka();
    noTone(pinBuzzer);
  }
}

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;
}