/*
 * My first Arduino program : LM (Rev.1 - 5-letter groups)
 *                               (Rev.2 - Speed control  )
 *                               (Rev.3 - Add '/' character + minor cleanup) 
 */

// Constants -
const boolean TEST = false;   // Canned sentence (all letters and period)
const boolean incNum = false; // Include numbers in 5-character groups
//
const int keyPressPin = 13;
const int timeConstant = 850; // Experimentally determined
const int minSpeed = 5;       // Prevent possible divide error and extend max speed
//  Digital pins to read speed as binary number (Add minSpeed to value)
const int d0 = 2;
const int d1 = 3;
const int d2 = 4;
const int d3 = 5;
const int d4 = 6;
//  Analog pin for speed potentiometer
const int a0 = 0;
//
const String testString = "The quick brown fox jumped over the lazy dog's back.";

// Variables -
int sndSpeed = 9; //   Will be revalued as read from Arduino
int dotTime;      //   Valued in setSpeed()
int dashTime;     // = dotTime + dotTime + dotTime;
int charTime;     // = dashTime;
int wordTime;     // = dashTime + dashTime + dotTime;

void setup() {
  // Runs once
  pinMode(keyPressPin, OUTPUT);
  pinMode(LED_BUILTIN, OUTPUT);     // Visual indicator
  //
  pinMode(d0, INPUT);               // Binary speed specification
  pinMode(d1, INPUT);
  pinMode(d2, INPUT);
  pinMode(d3, INPUT);
  pinMode(d4, INPUT);
  //
  digitalWrite(d0, LOW);            // Not sure this does anything..
  digitalWrite(d1, LOW);            // Each pin will be grounded
  digitalWrite(d2, LOW);            // through a 10K resistor if used
  digitalWrite(d3, LOW);
  digitalWrite(d4, LOW);
  //
  digitalWrite(keyPressPin, LOW);   // key up
  digitalWrite(LED_BUILTIN, LOW);   // LED off
  delay(2000);                      // Dark after upload
  randomSeed(analogRead(5));        // Initialize random number generator
                                    // (floating analog pin)
}

void loop() {
  // Runs repeatedly
  // Adjust speed
  analogReadSpeed();
  setSpeed();
  // 
  if (TEST) {
    outputString(testString);
    delay(4000); // Between repetitions of test string
  } 
  else outputString(fiveCharacterGroup() + " ");
}

String fiveCharacterGroup() {
  byte b;
  String s = "";
  
  for (int i=0; i<5; i++) {
    if (incNum) {
      b = random(36); // Can be changed to < 36 for partial numbers
      if (b < 26) b = 65 + b;
      else b = 22 + b;
    }
    else b = 65 + random(26);
    s = s + (char) b;
  }
  return s;
}

void dot() {
  digitalWrite(LED_BUILTIN, HIGH);   // Visual indicator on
  digitalWrite(keyPressPin, HIGH);   // key down
  delay(dotTime);
  digitalWrite(LED_BUILTIN, LOW);    // Visual indicator off
  digitalWrite(keyPressPin, LOW);    // key up
  delay(dotTime);
}

void dash() {
  digitalWrite(LED_BUILTIN, HIGH);   // Visual indicator on
  digitalWrite(keyPressPin, HIGH);   // key down
  delay(dashTime);
  digitalWrite(LED_BUILTIN, LOW);    // Visual indicator off
  digitalWrite(keyPressPin, LOW);    // key up
  delay(dotTime);
}

void outputString(String str) {
  char c;
  int i;
  str.toLowerCase();
  for (i = 0; i < str.length(); i ++) {
    c = str.charAt(i);
    if (c == ' ') delay(wordTime);
    else outputChar(c);
  }
}

void outputChar(char chr) {
  switch (chr) {
    case 'a' : dot(); dash(); break;
    case 'b' : dash(); dot(); dot(); dot(); break;
    case 'c' : dash(); dot(); dash(); dot(); break;
    case 'd' : dash(); dot(); dot(); break;
    case 'e' : dot(); break;
    case 'f' : dot(); dot(); dash(); dot(); break;
    case 'g' : dash(); dash(); dot(); break;
    case 'h' : dot(); dot(); dot(); dot(); break;
    case 'i' : dot(); dot(); break;
    case 'j' : dot(); dash(); dash(); dash(); break;
    case 'k' : dash(); dot(); dash(); break;
    case 'l' : dot(); dash(); dot(); dot();; break;
    case 'm' : dash(); dash(); break;
    case 'n' : dash(); dot(); break;
    case 'o' : dash(); dash(); dash(); break;
    case 'p' : dot(); dash(); dash(); dot(); break;
    case 'q' : dash(); dash(); dot(); dash(); break;
    case 'r' : dot(); dash(); dot(); break;
    case 's' : dot(); dot(); dot(); break;
    case 't' : dash(); break;
    case 'u' : dot(); dot(); dash(); break;
    case 'v' : dot(); dot(); dot(); dash(); break;
    case 'w' : dot(); dash(); dash(); break;
    case 'x' : dash(); dot(); dot(); dash(); break;
    case 'y' : dash(); dot(); dash(); dash(); break;
    case 'z' : dash(); dash(); dot(); dot(); break;
    case '0' : dash(); dash(); dash(); dash(); dash(); break;
    case '1' : dot(); dash(); dash(); dash(); dash();  break;
    case '2' : dot(); dot(); dash(); dash(); dash();  break;
    case '3' : dot(); dot(); dot(); dash(); dash();  break;
    case '4' : dot(); dot(); dot(); dot(); dash();  break;
    case '5' : dot(); dot(); dot(); dot(); dot(); break;
    case '6' : dash(); dot(); dot(); dot(); dot(); break;
    case '7' : dash(); dash(); dot(); dot(); dot(); break;
    case '8' : dash(); dash(); dash(); dot(); dot(); break;
    case '9' : dash(); dash(); dash(); dash(); dot(); break;
    case ',' : dash(); dash(); dot(); dot(); dash(); dash(); break;
    case '.' : dot(); dash(); dot(); dash(); dot(); dash(); break;
    case '?' : dot(); dot(); dash(); dash(); dot(); dot(); break;
    case '/' : dash(); dot(); dot(); dash(); dot();
    default : dash(); dot(); dot(); dot(); dash();
  }
  delay(charTime);
}

void readSpeed() {  // As binary number (words per minute)
  // Could do as int, however, sndSpeed is global variable
  int sum = 0;
  if (digitalRead(d0) == HIGH) sum = 1;
  if (digitalRead(d1) == HIGH) sum = sum + 2;
  if (digitalRead(d2) == HIGH) sum = sum + 4;
  if (digitalRead(d3) == HIGH) sum = sum + 8;
  if (digitalRead(d4) == HIGH) sum = sum + 16;
  if (sum > 0) sndSpeed = sum + minSpeed;  // words per minute
}

void analogReadSpeed() {  // As voltage * 1024 / 5
  sndSpeed = analogRead(a0) / 32 + minSpeed; // 0-1023 to w.p.m.
}

void setSpeed() { // After initialization, based on input from board
  dotTime = timeConstant / sndSpeed;
  dashTime = dotTime + dotTime + dotTime;
  charTime = dashTime;
  wordTime = dashTime + dashTime + dotTime;
}