making a monkey keychain scream a morse code message, while displaying on a little 128x64 OLED screen

morse-ape-scream.ino

#include <SPI.h>
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

#define OLED_MOSI   9
#define OLED_CLK   10
#define OLED_DC    11
#define OLED_CS    12
#define OLED_RESET 13
Adafruit_SSD1306 display(OLED_MOSI, OLED_CLK, OLED_DC, OLED_RESET, OLED_CS);

int current_char = 0;
String str = "hello world";

void setup()   {
  Serial.begin(9600);
  display.begin(SSD1306_SWITCHCAPVCC);
}

void loop() {
  int highlighted_char = current_char % str.length();

  // write the string to the screen
  display.clearDisplay();
  ape_scream_string(str, 1, highlighted_char);
  display.display();

  // now make let Chuggzilla do his thing
  morse_transmit(str[highlighted_char]);

  current_char++;
}

void ape_scream_string(String s, int row, int highlightedPosition) {
  for (int i = 0; i < s.length(); i++) {
    ape_scream_char(s[i], i, row, highlightedPosition);
  }
}

void ape_scream_char(char c, int n, int row, int highlightedPosition) {
  if (n == highlightedPosition) {
    display.drawChar(n * 6, row * 8, c, BLACK, WHITE, 1);
  } else {
    display.drawChar(n * 6, row * 8, c, WHITE, BLACK, 1);
  }
}

// https://github.com/smcl/arduino_morse quickly ported from C
// using pin 2 instead of pin 13.
#define MORSE_UNIT 100

void morse_setup() {
  pinMode(2, OUTPUT);
}

void key_down() {
  digitalWrite(2, HIGH);
}

void key_up() {
  digitalWrite(2, LOW);
}

void key_press(int n) {
  key_down();

  delay(n * MORSE_UNIT);

  key_up();
}

void dit() {
  key_press(1);
}

void dah() {
  key_press(3);
}

void morse_nop() {
  delay(3 * MORSE_UNIT);
}

String morse_translate(char c) {
  switch (c) {
    case 'a':
      return ".-";
    case 'b':
      return "-...";
    case 'c':
      return "-.-.";
    case 'd':
      return "-..";
    case 'e':
      return ".";
    case 'f':
      return "..-.";
    case 'g':
      return "--.";
    case 'h':
      return "....";
    case 'i':
      return "..";
    case 'j':
      return ".---";
    case 'k':
      return "-.-";
    case 'l':
      return ".-..";
    case 'm':
      return "--";
    case 'n':
      return "-.";
    case 'o':
      return "---";
    case 'p':
      return ".--.";
    case 'q':
      return "--.-";
    case 'r':
      return ".-.";
    case 's':
      return "...";
    case 't':
      return "-";
    case 'u':
      return "..-";
    case 'v':
      return "...-";
    case 'w':
      return ".--";
    case 'x':
      return "-..-";
    case 'y':
      return "-.--";
    case 'z':
      return "--..";
    case '0':
      return "-----";
    case '1':
      return ".----";
    case '2':
      return "..---";
    case '3':
      return "...--";
    case '4':
      return "....-";
    case '5':
      return ".....";
    case '6':
      return "-....";
    case '7':
      return "--...";
    case '8':
      return "---..";
    case '9':
      return "----.";
    default:
      return " ";
  }
}

void morse_transmit(char ascii_char) {
  String morse_char = morse_translate(ascii_char);

  delay(MORSE_UNIT);

  for (int i = 0; i < morse_char.length(); i++) {
    delay(MORSE_UNIT);

    switch (morse_char[i]) {
      case '.':
        dit();
        break;
      case '-':
        dah();
        break;
      default:
        morse_nop();
        break;
    }
  }
}