#define PIR_PIN 2
#define LED_PIN 4
void setup() {
  // put your setup code here, to run once:
    pinMode(PIR_PIN,INPUT);
    pinMode(LED_PIN,OUTPUT);  // opens serial port, sets data rate to 9600 bps
}
void loop()
{
    if(digitalRead(PIR_PIN))
        digitalWrite(LED_PIN,HIGH);
    else
      digitalWrite(LED_PIN,LOW);
}