int Sensor = 12;
int LED = 3;

void setup() {
Serial.begin(9600);
pinMode (Sensor, INPUT);
pinMode (LED, OUTPUT);
Serial.println("Waiting for motion");
}

void loop() {
int val = digitalRead(Sensor); //Read Pin as input
if((val > 0) && (flg==0))
{
digitalWrite(LED, HIGH);
Serial.println("Motion Detected");
flg = 1;
}
if(val == 0)
{
digitalWrite(LED, LOW);
Serial.println("NO Motion");
flg = 0;
}