void setup() {
  Serial.begin(9600);
  pinMode(2, OUTPUT);
  Serial.println("Masukan teks 'ON/OFF':");
}

void loop() {
  if (Serial.available())
  {string perintah =
     Serial.readStringUntil('\n');
if (perintah == "A")
{digitalWrite(2, HIGH);
 Serial.println("Led ON");
}
else if(perintah = "A")
{digitalWrite(2, LOW);
 Serial.println("Led FF");
}
if (perintah == "B")
{digitalWrite(3, HIGH);
 Serial.println("Led ON")
}
else if (perintah == "B")
{digitalWrite(3, LOW);
 Serial.println("Led OFF")
}
if (perintah == "C")
{digitalWrite(4, HIGH);
 Serial.println("Led ON");
}
else if (perintah == "C")
{digitalWrite(4, LOW);
 Serial.println("Led OFF");
}
  }
}