int led =12;            
 int data =2 ;       
 int state =LOW ;      
 int value =0;            

void setup() {
  pinMode(led, OUTPUT);      
  pinMode(data, INPUT);     

  Serial.begin(9600);
}

void loop() {
  value = digitalRead(data);  
  if (value == HIGH) {           
    digitalWrite(led, HIGH);  
    if (state == LOW) {
     
      Serial.println("Motion detected!");
      
      state = HIGH;
    }
  } else {
    digitalWrite(led, LOW); 
    if (state == HIGH) {
      
      Serial.println("Motion ended!");
     
      state = LOW;
    }
  }
}