int ledPin = 13;
int incomingByte;
int letterdelayPeriod = 300;
int spacedelayPeriod = 700;

void setup()
{
  Serial.begin(9600);
  pinMode (ledPin, OUTPUT);
}

void dot()
{
  digitalWrite (ledPin, HIGH);
  delay (100);
  digitalWrite (ledPin, LOW);
  delay (100);
}

void dash()
{
  digitalWrite (ledPin, HIGH);
  delay (300);
  digitalWrite (ledPin, LOW);
  delay (100);
}

void loop()
{
  if (Serial.available () > 0)
  {
    incomingByte = Serial.read();
    if (incomingByte == 'a')
    {
      dot();
      dash();
      delay (letterdelayPeriod);
    }
    if (incomingByte == 'b')
    {
      dash();
      dot();
      dot();
      dot();
      delay (letterdelayPeriod);
    }
    if (incomingByte == 'c')
    {
      dash();
      dot();
      dash();
      dot();
      delay (letterdelayPeriod);
    }
    if (incomingByte == 'd')
    {
      dash();
      dot();
      dot();
      delay (letterdelayPeriod);
    }
    if (incomingByte == 'e')
    {
      dot();
      delay (letterdelayPeriod);
    }
    if (incomingByte == 'f')
    {
      dot();
      dot();
      dash();
      dot();
      delay (letterdelayPeriod);
    }
    if (incomingByte == 'g')
    {
      dash();
      dash();
      dot();
      delay (letterdelayPeriod);
    }
    if (incomingByte == 'h')
    {
      dot();
      dot();
      dot();
      dot();
      delay (letterdelayPeriod);
    }
    if (incomingByte == 'i')
    {
      dot();
      dot();
      delay (letterdelayPeriod);
    }
    if (incomingByte == 'j')
    {
      dot();
      dash();
      dash();
      dash();
      delay (letterdelayPeriod);
    }
    if (incomingByte == 'k')
    {
      dash();
      dot();
      dash();
      delay (letterdelayPeriod);
    }
    if (incomingByte == 'l')
    {
      dot();
      dash();
      dot();
      dot();
      delay (letterdelayPeriod);
    }
    if (incomingByte == 'm')
    {
      dash();
      dash();
      delay (letterdelayPeriod);
    }
    if (incomingByte == 'n')
    {
      dash();
      dot();
      delay (letterdelayPeriod);
    }
     if (incomingByte == 'o')
    {
      dash();
      dash();
      dash();
    }
    if (incomingByte == 'p')
    {
      dot();
      dash();
      dash();
      dot();
      delay (letterdelayPeriod);
    }
    if (incomingByte == 'q')
    {
      dash();
      dash();
      dot();
      dash();
      delay (letterdelayPeriod);
    }
    if (incomingByte == 'r')
    {
      dot();
      dash();
      dot();
      delay (letterdelayPeriod);
    }
    if (incomingByte == 's')
    {
      dot();
      dot();
      dot();
      delay (letterdelayPeriod);
    }
    if (incomingByte == 't')
    {
      dash();
      delay (letterdelayPeriod);
    }
    if (incomingByte == 'u')
    {
      dot();
      dot();
      dash();
      delay (letterdelayPeriod);
    }
    if (incomingByte == 'v')
    {
      dot();
      dot();
      dot();
      dash();
      delay (letterdelayPeriod);
    }
    if (incomingByte == 'w')
    {
      dot();
      dash();
      dash();
      delay (letterdelayPeriod);
    }
    if (incomingByte == 'y')
    {
      dash();
      dot();
      dash();
      dash();
      delay (letterdelayPeriod);
    }
    if (incomingByte == 'z')
    {
      dash();
      dash();
      dot();
      dot();
      delay (letterdelayPeriod);
    }
    if (incomingByte == ' ')
    {
      delay (spacedelayPeriod);
    }
  }
}