void setup() {
  pinMode(9, OUTPUT); // SALIDA LDR
  pinMode(2, INPUT); // ENTRADA LED

  Serial.begin(9600);

}

void loop() {
  Serial.print("Signal - ");// put your main code here, to run repeatedly:

Serial.println(digitalRead(2));

  if (digitalRead(2)== HIGH){
    digitalWrite(9, LOW);
  }
  if (digitalRead(2)==LOW){
    digitalWrite(9, HIGH);
  }
}