#define LED 3


void setup() {
  pinMode(LED, OUTPUT);
  Serial.begin(9600);
  Serial.println("Enter your text here : ? ");
}

void loop() {
  if(Serial.available()){
    String text = Serial.readString();
    Serial.println(text);
    if(text == "on" || text == "ON"){
      digitalWrite(LED, HIGH);
    }
    else{
      digitalWrite(LED, LOW);
    } 
    //int int_number = Serial.parseInt();
    //float float_number = Serial.parseFloat();
    
    //Serial.println(int_number);
    //Serial.println(float_number);
    //Serial.end();
  }

}