int led =13 ;
int sensor = 2;
int state =LOW;
int val = 0;
void setup()
{
  pinMode(led, OUTPUT); 
  pinMode(sensor, INPUT); 
  Serial.begin(9600);
}

void loop() 
{
 val=digitalRead(sensor);
 if (val == HIGH)
  {
    digitalWrite(led, HIGH);
    delay(100);
    if (state==LOW)
    {
     Serial.println("motion detected");
     state=HIGH;
    }
  }
 else
 {
   digitalWrite(led, LOW);
   delay(200);
   Serial.println("motion stopped");
 }
}