//vars
#define LED_BLUE    1
#define SENSOR_PIR  4
const int TIMER = 1;
bool PIR;

void setup() {
  
  pinMode(SENSOR_PIR, INPUT);
  pinMode(LED_BLUE, OUTPUT);
  digitalWrite(LED_BLUE, LOW);

}

void loop() {
  
  PIR = digitalRead(SENSOR_PIR);

  if(PIR){
    digitalWrite(LED_BLUE, HIGH);
  }else{
    digitalWrite(LED_BLUE, LOW);
  }
}