Build Instructions

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  #include<Serial.h>

  //Baudot lookup table

  unsigned char lookup[] = {

  ' ', 'E', ' ', 'A', ' ', 'S', 'I', 'U',

  '\n', 'D', 'R', 'J', 'N', 'F', 'C', 'K',

  'T', 'Z', 'L', 'W', 'H', 'Y', 'P', 'Q',

  'O', 'B', 'G', 0, 'M', 'X', 'V', 0,

  ' ', '3', '\n', '-', ' ', '`', '8', '7',

  '\r', ' ', '4', '\'', ',', '!', ':', '(',

  '5', '+', ')', '2', '$', '6', '0', '1',

  '9', '?', '&', 0, '.', '/', ';', 0 };

  const int RELAY_PIN = 4;

  const int CHAR_DELAY = 22; //milliseconds

  const int START_BIT_DELAY = 22; // milliseconds

  const int STOP_BIT_DELAY = 44; // milliseconds

  const int SPACE = 4;

  const int F_SHIFT = 27;

  const int L_SHIFT = 31;

  const int CR = 8;

  const int LF = 2;

  boolean letters_on = true;

  boolean print_debug = false;

  /* transmits 5 bit integers */

  void byte_send(int _byte){

  send_start_bit();

  // loop through all 5 bits and send a space for zero bits, and mark for one bits.

  for(int _bit = 0; _bit < 5; _bit++){

  switch (bitRead(_byte,_bit)) {

  case 0:

  Serial.print(0);

  space();

  break;

  case 1:

  Serial.print(1);

  mark();

  break;

  } // end switch

  } // end for loop

  send_stop_bit();

  } // end byte_send()

  /* Lookup and decode characters before transmitting. */

  void char_send(char letter){

  char l = toupper(letter);

  Serial.print("sending ");

  Serial.print(l);

  int idx = lookupChar(l);

  Serial.print(" idx: ");

  Serial.print(idx);

  Serial.print(" Binary: ");

  // check for offset

  if (31 < idx){ // shift for figures

  if (letters_on){

  figure_shift();

  }

  idx = idx - 32;

  } else { // shift for letters

  if (false == letters_on){

  letter_shift();

  }

  }

  byte_send(idx);

  Serial.println();

  } // end char_send()

  void letter_shift(){

  Serial.print(" [L_SHIFT] ");

  letters_on = true;

  byte_send(L_SHIFT);

  }

  void figure_shift(){

  Serial.print(" [F_SHIFT] ");

  letters_on = false;

  byte_send(F_SHIFT);

  }

  void cr(){ Serial.print(" <CR> "); byte_send(CR); }

  void lf(){ Serial.print(" <LF>"); byte_send(LF); }

  void send_start_bit(){

  digitalWrite(RELAY_PIN, HIGH);

  delay(START_BIT_DELAY);

  }

  void send_stop_bit(){

  digitalWrite(RELAY_PIN, LOW);

  delay(STOP_BIT_DELAY);

  }

  void mark(){

  digitalWrite(RELAY_PIN, LOW);

  delay(CHAR_DELAY);

  }

  void space(){

  digitalWrite(RELAY_PIN, HIGH);

  delay(CHAR_DELAY);

  }

  int lookupChar(char letter){

  if (' ' == letter){ return 4; }

  for (int lookupIdx = 0; lookupIdx < sizeof(lookup); lookupIdx++){

  if (letter == lookup[lookupIdx]){

  return lookupIdx;

  }

  }

  return 0;

  }

  void setup(){

  Serial.begin(115200);

  pinMode(RELAY_PIN, OUTPUT);

  pinMode(5, OUTPUT);

  digitalWrite(RELAY_PIN, LOW);

  }

  void demo(){

  cr();

  lf();

  letter_shift();

  for (int i = 0; i < 34; i++){

  char_send('R');

  char_send('Y');

  }

  }

  void demo2(){

  int idx = 0;

  char demo_string[] = "THE QUICK BROWN FOX JUMPED OVER THE LAZY DOG'S BACK 1234567890 TIMES";

  cr();

  lf();

  letter_shift();

  for (int i = 0; i < sizeof(demo_string); i++){

  char_send(demo_string[i]);

  }

  }

  void demo3(){

  int cur = 0;

  while (cur < 68) {

  if (Serial.available() > 0) {

  Serial.print(cur);

  Serial.print(": ");

  char_send(Serial.read());

  cur++;

  }

  }

  cr();

  lf();

  }

  void loop() {

  demo();

  demo2();

  //demo3();

  }

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