void setup() {
  // put your setup code here, to run once:
  Serial.begin(115200);
  Serial.println(4,INPUT_PULLUP);
}

void loop() {
  int a=digitalRead(4);
  Serial.println(a);

  if(a==HIGH)
  {
    Serial.println("motion detected");
  }
  if (a==LOW)
  {  
     Serial.println("motion not detected");
  }   
  // put your main code here, to run repeatedly:
  delay(10); // this speeds up the simulation
}