#define pinRelay 3
#define ECHO_PIN 5
#define TRIG_PIN 4
int pir = 2;               
int pirState = LOW;          
int val = 0;                   

float x = 400/397.63;

void setup() {
  // put your setup code here, to run once:  
  pinMode(TRIG_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);

  pinMode(pir, INPUT);     
  pinMode(pinRelay, OUTPUT);
  Serial.begin(9600);

}

void loop() {
  // put your main code here, to run repeatedly:
  digitalWrite(TRIG_PIN, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);
  

  int duration = pulseIn(ECHO_PIN, HIGH);
  float distance = duration * 0.034 * x / 2;

  int val = digitalRead(pir);  
   if (val == HIGH && distance < 100) {  
    if (pirState == LOW) {
      Serial.println("AWAS MALING!");
      pirState = HIGH;
    }

    digitalWrite(pinRelay, LOW);
    delay(1000);
    digitalWrite(pinRelay, HIGH);

  } else {
    digitalWrite(pinRelay, LOW);
    if (pirState == HIGH) {
      Serial.println("TIDAK TERDETEKSI!");
      pirState = LOW;
    }
  }
  }