This is my ET Phone Home "Speak and Read" Morse Code DeCoder.

IO_Machine.ino

/*
  This is my ET Phone Home "Speak and Read" Morse Code DeCoder.

  The Arduino code can be adapted for other inputs and outputs.

  Other ways that this Input/Output machine can be used are available at www.13wires.com
  
  I chose the Arduino Mega because it has additional serial ports and pins.
  
  */

//  Let's start with identifying the 13 wires.
const int COL_W1 = 48;
const int COL_W2 = 46;
const int ROW_W3 = 44;
const int ROW_W4 = 42;
const int ROW_W5 = 40;
const int ROW_W6 = 38;
const int ROW_W7 = 36;
const int ROW_W8 = 34;
const int ROW_W9 = 32;
const int ROW_W10 = 30;
const int COL_W11 = 28;
const int COL_W12 = 26;
const int COL_W13 = 24;

int incomingByte;      // a variable to read incoming Serial2 data
char receivedMorse; // as a character

void setup() {

  Serial.begin(9600);
  Serial2.begin(9600);
  
  // initialize the LED pins as an outputs:
  pinMode(COL_W1, OUTPUT);
  pinMode(COL_W2, OUTPUT);
  pinMode(COL_W11, OUTPUT);
  pinMode(COL_W12, OUTPUT);
  pinMode(COL_W13, OUTPUT);
  pinMode(ROW_W3, OUTPUT);
  pinMode(ROW_W4, OUTPUT);
  pinMode(ROW_W5, OUTPUT);
  pinMode(ROW_W6, OUTPUT);
  pinMode(ROW_W7, OUTPUT);
  pinMode(ROW_W8, OUTPUT);
  pinMode(ROW_W9, OUTPUT);
  pinMode(ROW_W10, OUTPUT);

  reset_pins();
  set_pins(ROW_W5, COL_W1); //This is like pushing the "OFF" button.
  delay(200);
  reset_pins_off();
  reset_pins();
  set_pins(ROW_W8, COL_W13); //This is like pushing the "ON" button.
  delay(200);
  Serial.println ("ET Phone Home!");
  Serial.println();
  reset_pins_off();
}

void loop() {
  
  // receive Morse Characters through Serial2
  if (Serial2.available()) {

  char receivedMorse = incomingByte;
  receivedMorse = Serial2.read();
  
   if (incomingByte == ' '); {
     Serial2.print ("Do nothing. That's a space.");
    }
    
    if (receivedMorse == '1') {
    reset_pins();
    set_pins(ROW_W8, COL_W11); //Loads Letter Stumper
    Serial.println ("That's a #1 ...di-dah-dah-dah-dah!");
    Serial.println ("Starting Letter Stumper!");
    Serial.println();
    delay(200);
    reset_pins_off();   
    }

    if (receivedMorse == '2') { 
    reset_pins();
    set_pins(ROW_W8, COL_W1); //Loads Read It
    Serial.println ("That's a #2 ...di-di-dah-dah-dah!");
    Serial.println ("Starting Read It!");
    Serial.println();
    delay(200);
    reset_pins_off();
    }

    if (receivedMorse == '3') { 
    reset_pins();
    set_pins(ROW_W5, COL_W13); //Loads Word Maker
    Serial.println ("That's a #3 ...di-di-di-dah-dah!");
    Serial.println ("Starting Word Maker!");
    Serial.println();
    delay(200);
    reset_pins_off();
    }

    if (receivedMorse == '4') { 
    reset_pins();
    set_pins(ROW_W8, COL_W12); //Loads Hear It
    Serial.println ("That's a #4 ...di-di-di-di-dah!");
    Serial.println ("Starting Hear It!");
    Serial.println();
    delay(200);
    reset_pins_off();
    }
    
    if (receivedMorse == '5') {
      reset_pins();
      set_pins(ROW_W5, COL_W2);
      Serial.println ("That's a #5 ...di-di-di-di-dit!");
      Serial.println ("GO!");
      Serial.println();
      delay(200);
      reset_pins_off();
    }
    if (receivedMorse == 'A') {
      reset_pins();
      set_pins(ROW_W6, COL_W1);
      Serial.println ("That's an A ...di-dah!");
      Serial.println();
      delay(200);
      reset_pins_off(); 
    }
      if (receivedMorse == 'B') {
      reset_pins();
      set_pins(ROW_W6, COL_W2);
      Serial.println ("That's a B ...dah-di-di-dit!");
      Serial.println();
      delay(200);
      reset_pins_off(); 
    }
    if (receivedMorse == 'C') {
      reset_pins();
      set_pins(ROW_W6, COL_W11);
      Serial.println ("That's a C ...dah-di-dah-dit!");
      Serial.println();
      delay(200);
      reset_pins_off(); 
    }
    if (receivedMorse == 'D') {
      reset_pins();
      set_pins(ROW_W6, COL_W12);
      Serial.println ("That's a D ...dah-di-dit!");
      Serial.println();
      delay(200);
      reset_pins_off();
    }
    if (receivedMorse == 'E') {
      reset_pins();
      set_pins(ROW_W6, COL_W13);
      Serial.println ("That's an E ...dit!");
      Serial.println();
      delay(200);
      reset_pins_off();
    }
    if (receivedMorse == 'F') {
      reset_pins();
      set_pins(ROW_W7, COL_W1);
      Serial.println ("That's an F ...di-di-dah-dit!");
      Serial.println();
      delay(200);
      reset_pins_off(); 
    }
    if (receivedMorse == 'G') {
      reset_pins();
      set_pins(ROW_W7, COL_W2);
      Serial.println ("That's a G ...dah-dah-dit!");
      Serial.println();
      delay(200);
      reset_pins_off(); 
    }
    if (receivedMorse == 'H') {
      reset_pins();
      set_pins(ROW_W7, COL_W11);
      Serial.println ("That's an H ...di-di-di-dit!");
      Serial.println();
      delay(200);
      reset_pins_off(); 
    }
    if (receivedMorse == 'I') {
      reset_pins();
      set_pins(ROW_W7, COL_W12);
      Serial.println ("That's an I ...di-dit!");
      Serial.println();
      delay(200);
      reset_pins_off();
    }
    if (receivedMorse == 'J') {
      reset_pins();
      set_pins(ROW_W7, COL_W13);
      Serial.println ("That's a J ...di-dah-dah-dah!");
      Serial.println();
      delay(200);
      reset_pins_off();
    }
    if (receivedMorse == 'K') {
      reset_pins();
      set_pins(ROW_W4, COL_W1);
      Serial.println ("That's a K ...dah-di-dah!");
      Serial.println();
      delay(200);
      reset_pins_off();
    }
    if (receivedMorse == 'L') {
      reset_pins();
      set_pins(ROW_W4, COL_W2);
      Serial.println ("That's an L ...di-dah-di-dit!");
      Serial.println();
      delay(200);
      reset_pins_off(); 
    }
    if (receivedMorse == 'M') {
      reset_pins();
      set_pins(ROW_W4, COL_W11);
      Serial.println ("That's an M ...dah-dah!");
      Serial.println();
      delay(200);
      reset_pins_off(); 
    }
    if (receivedMorse == 'N') {
      reset_pins();
      set_pins(ROW_W4, COL_W12);
      Serial.println ("That's an N ...dah-dit!");
      Serial.println();
      delay(200);
      reset_pins_off();
    }
    if (receivedMorse == 'O') {
      reset_pins();
      set_pins(ROW_W4, COL_W13);
      Serial.println ("That's an O ...dah-dah-dah!");
      Serial.println();
      delay(200);
      reset_pins_off();
    }
    if (receivedMorse == 'P') {
      reset_pins();
      set_pins(ROW_W9, COL_W1);
      Serial.println ("That's a P ...di-dah-dah-dit!");
      Serial.println();
      delay(200);
      reset_pins_off(); 
    }
    if (receivedMorse == 'Q') {
      reset_pins();
      set_pins(ROW_W9, COL_W2);
      Serial.println ("That's a Q ...dah-dah-di-dah!");
      Serial.println();
      delay(200);
      reset_pins_off(); 
    }
    if (receivedMorse == 'R') {
      reset_pins();
      set_pins(ROW_W9, COL_W11);
      Serial.println ("That's an R ...di-dah-dit!");
      Serial.println();
      delay(200);
      reset_pins_off(); 
    }
    if (receivedMorse == 'S') {
      reset_pins();
      set_pins(ROW_W9, COL_W12);
      Serial.println ("That's an S ...di-di-dit!");
      Serial.println();
      delay(200);
      reset_pins_off();
    }
    if (receivedMorse == 'T') {
      reset_pins();
      set_pins(ROW_W9, COL_W13);
      Serial.println ("That's a T ...dah!");
      Serial.println();
      delay(200);
      reset_pins_off();
    }
    if (receivedMorse == 'U') {
      reset_pins();
      set_pins(ROW_W3, COL_W1);
      Serial.println ("That's a U ...di-di-dah!");
      Serial.println();
      delay(200);
      reset_pins_off();
    }
    if (receivedMorse == 'V') {
      reset_pins();
      set_pins(ROW_W3, COL_W2);
      Serial.println ("That's a V ...di-di-di-dah!");
      Serial.println();
      delay(200);
      reset_pins_off(); 
    }
    if (receivedMorse == 'W') {
      reset_pins();
      set_pins(ROW_W3, COL_W11);
      Serial.println ("That's a W ...di-dah-dah!");
      Serial.println();
      delay(200);
      reset_pins_off(); 
    }
    if (receivedMorse == 'X') {
      reset_pins();
      set_pins(ROW_W3, COL_W12);
      Serial.println ("That's an X ...dah-di-di-dah!");
      Serial.println();
      delay(200);
      reset_pins_off();
    }
    if (receivedMorse == 'Y') {
      reset_pins();
      set_pins(ROW_W3, COL_W13);
      Serial.println ("That's a Y ...dah-di-dah-dah!");
      Serial.println();
      delay(200);
      reset_pins_off();
    }
    if (receivedMorse == 'Z') {
      reset_pins();
      set_pins(ROW_W10, COL_W1);
      Serial.println ("That's a Z ...dah-dah-di-dit!");
      Serial.println();
      delay(200);
      reset_pins_off(); 
    }
  }
}
    
void set_pins(int high_pin, int low_pin)
{
  // reset all the pins
  reset_pins();

  // set the high and low pins to output
  pinMode(high_pin, OUTPUT);
  pinMode(low_pin, OUTPUT);

  // set high pin to logic high, low to logic low
  digitalWrite(high_pin, HIGH);
  digitalWrite(low_pin,LOW);
}

void reset_pins()
{
  // start by ensuring all pins are ready to register the character
  //COLs are set to HIGH in order to reverse the current, and hence turn them off
  digitalWrite(COL_W1, HIGH);
  digitalWrite(COL_W2, HIGH);
  digitalWrite(COL_W11, HIGH);
  digitalWrite(COL_W12, HIGH);
  digitalWrite(COL_W13, HIGH);
  digitalWrite(ROW_W3, LOW);
  digitalWrite(ROW_W4, LOW);
  digitalWrite(ROW_W5, LOW);
  digitalWrite(ROW_W6, LOW);
  digitalWrite(ROW_W7, LOW);
  digitalWrite(ROW_W8, LOW);
  digitalWrite(ROW_W9, LOW);
  digitalWrite(ROW_W10, LOW);
}
void reset_pins_off()
{
  //COLUMNS and ROWS all set LOW, just so we don't have a circuit anywhere messing things up
  digitalWrite(COL_W1, LOW);
  digitalWrite(COL_W2, LOW);
  digitalWrite(COL_W11, LOW);
  digitalWrite(COL_W12, LOW);
  digitalWrite(COL_W13, LOW);
  digitalWrite(ROW_W3, LOW);
  digitalWrite(ROW_W4, LOW);
  digitalWrite(ROW_W5, LOW);
  digitalWrite(ROW_W6, LOW);
  digitalWrite(ROW_W7, LOW);
  digitalWrite(ROW_W8, LOW);
  digitalWrite(ROW_W9, LOW);
  digitalWrite(ROW_W10, LOW);
}