#define LIGHT 13
#define FAN 12

void setup() {
  pinMode(LIGHT, OUTPUT);
  pinMode(FAN, OUTPUT);
  Serial.begin(9600);
  Serial.println("Send 'A' for Light ON, 'a' for Light OFF");
  Serial.println("Send 'B' for Fan ON, 'b' for Fan OFF");
}

void loop() {
  if (Serial.available()) {
    char cmd = Serial.read();
    
    if (cmd == 'A') {
      digitalWrite(LIGHT, HIGH);
      Serial.println("Light ON");
    }
    else if (cmd == 'a') {
      digitalWrite(LIGHT, LOW);
      Serial.println("Light OFF");
    }
    else if (cmd == 'B') {
      digitalWrite(FAN, HIGH);
      Serial.println("Fan ON");
    }
    else if (cmd == 'b') {
      digitalWrite(FAN, LOW);
      Serial.println("Fan OFF");
    }
  }
}