int sensor=6;
int led=2;
int n;
void setup()
{
  pinMode(led, OUTPUT);
  pinMode(sensor, INPUT);
  Serial.begin(9600);
}
void loop()
{
  n=digitalRead(sensor);
  if(n==HIGH){
    Serial.println("Motion not detected");
    digitalWrite(led, HIGH);
    delay(1000);
  }
  if(n==LOW)
 {
  digitalWrite(led, LOW);
 Serial.println("Motion detected");
 delay(1000);
}
}