int Servo = 9;
int PirSensor = 3;
int pirState = 0;
int val = 0;

void setup() {
  // put your setup code here, to run once:
  pinMode(Servo, OUTPUT);
  pinMode(pirSensor, INPUT);

  Serial.begin(9600);


}

void loop() {
  // put your main code here, to run repeatedly:

val = digitalRead(PirSensor);
if (val == HIGH){  //if cat tough the Pir sensor
  digitalWrite(Servo, HIGH);
  if (pirState == LOW){
    Serial.println("蕃薯有飯食!");
    pirState = HIGH;
  }
}else{
  digitalWrite(Servo, Low);
  if (pirState == HIGH){
    Serial.println("蕃薯走了!!!!!");
    pirState = LOW;

  }
}

}