#define ledPin 13

void setup() 
{
  Serial.begin(9600);
  pinMode(ledPin, OUTPUT);
  Serial.println("You can type numbers 1,0 or the charchter B or M");
}

void loop() 
{
  int i = 0;
  if (Serial.available() > 0) 
  {
    char data = Serial.read();
    if (data == '1') 
    {
      //Turn on
      digitalWrite(ledPin, HIGH);
      Serial.println("you have pressed the number 1");
    } 
    else if (data == '0') 
    {
      // Turn off
      digitalWrite(ledPin, LOW);
      Serial.println("you have pressed the number 0");
    } 
    else if (data == 'B') 
    {
      // Blink
      Serial.println("you have pressed the letter B");
      while (i < 3)
      {
      digitalWrite(ledPin, HIGH);
      delay(500);
      digitalWrite(ledPin, LOW);
      delay(500);
      i++;
      }
    } 
    else if (data == 'M') 
    {
      // Send a message to the monitor
      Serial.println("you have pressed the letter M");
      Serial.println("I learned how to use serial communication between the computer and Arduino.");
    }
  }
}