An Electronic D20 using an 0.96" OLED display and an Arduino

D20.ino

# Arduino Electronic D20
# Created by Joe Coburn for Make Use Of
# 15/01/2017
# http://www.makeuseof.com/

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

Adafruit_SSD1306 display(4); // create display object
const int buttonPin = 2; // the number of the button pin

void setup()   {
    display.begin(SSD1306_SWITCHCAPVCC, 0x3C); // setup the OLED
    pinMode(buttonPin, INPUT); // setup button  
}

void loop() {
    if(digitalRead(buttonPin) == HIGH) {
        delay(15);
        if(digitalRead(buttonPin) == HIGH) {
              display.fillScreen(BLACK); // erase the whole display
              display.setTextSize(3);
              display.setTextColor(WHITE);
              
              int roll = TrueRandom.random(1, 21); // store the random number
              if(roll == 20) {
                  drawExplosion();
                  display.setCursor(80, 21);
                  display.println("20"); 
              }
              else if(roll == 1) {
                  display.setCursor(24, 21);
                  display.println("1"); 
                  drawSkull();  
              }
              else if (roll < 10) {
                  // single character number
                  display.setCursor(57, 21);
                  display.println(roll); // write the roll
                  drawDie(); // draw the outline
              }
              else {
                  // dual character number
                  display.setCursor(47, 21); 
                  display.println(roll); // write the roll 
                  drawDie(); // draw the outline
              }
              
              display.display(); // write to display
              delay(100);
        }
    }
}

void drawDie() {
    display.drawRect((display.width() - 64) / 2, 0, 64, 64, WHITE);
}

void drawExplosion() {
    // store image in EEPROM
    static const unsigned char PROGMEM imExp[] = {
        0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x30,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0xfc,0x00,0x00,0x00,0x00,0x00,0x78,0x7f,0xff,0xc0,0x00,0x00,0x00,0x00,0xfe,0xff,0xff,0xf0,0x00,0x00,0x00,0x3f,0xff,0xff,0xff,0xfb,0x00,0x00,0x00,0x7f,0xff,0xff,0xff,0xff,0xc0,0x00,0x00,0x7f,0xff,0xff,0xff,0xff,0xff,0x00,0x01,0xff,0xff,0xff,0xff,0xff,0xff,0x80,0x03,0xff,0xff,0xff,0xff,0xff,0xff,0x80,0x03,0xff,0xff,0xff,0xff,0xff,0xff,0x80,0x03,0xff,0xff,0xff,0xff,0xff,0xff,0xc0,0x03,0xff,0xff,0xff,0xff,0xff,0xff,0xf0,0x07,0xff,0xff,0xff,0xff,0xff,0xff,0xf0,0x07,0xff,0xff,0xff,0xff,0xff,0xff,0xf0,0x07,0xff,0xff,0xff,0xff,0xff,0xff,0xe0,0x07,0xff,0xff,0xff,0xff,0xff,0xff,0xc0,0x0f,0xff,0xff,0xff,0xff,0xff,0xff,0xe0,0x1f,0xff,0xff,0xff,0xff,0xff,0xff,0xe0,0x1f,0xff,0xff,0xff,0xff,0xff,0xff,0xe0,0x0f,0xff,0xff,0xff,0xff,0xff,0xff,0xf0,0x03,0xff,0xff,0xff,0xff,0xff,0xff,0xf0,0x03,0xff,0xff,0xff,0xff,0xff,0xff,0xf0,0x03,0xff,0xff,0xff,0xff,0xff,0xff,0xe0,0x01,0xff,0xff,0xff,0xff,0xff,0xff,0x00,0x00,0x0f,0xff,0xff,0xff,0xff,0xfe,0x00,0x00,0x07,0xff,0xff,0xf9,0xff,0xd8,0x00,0x00,0x00,0x3f,0xff,0xf0,0x0f,0x00,0x00,0x00,0x00,0x1f,0x1f,0xf0,0x00,0x00,0x00,0x00,0x00,0x00,0x0f,0xe0,0x00,0x00,0x00,0x00,0x00,0x00,0x0f,0xe0,0x00,0x00,0x00,0x00,0x00,0x00,0x0f,0xe0,0x00,0x00,0x00,0x00,0x00,0x00,0x0f,0xf0,0x00,0x00,0x00,0x00,0x00,0x00,0x0f,0xf0,0x00,0x00,0x00,0x00,0x00,0x00,0x0f,0xf0,0x00,0x00,0x00,0x00,0x00,0x00,0x3f,0xf8,0x00,0x00,0x00,0x00,0x00,0x00,0x7f,0xff,0x00,0x00,0x00,0x00,0x00,0x00,0x7f,0xff,0x00,0x00,0x00,0x00,0x00,0x00,0x7f,0xff,0x00,0x00,0x00,0x00,0x00,0x00,0x7f,0xfe,0x00,0x00,0x00,0x00,0x00,0x00,0x7f,0xfc,0x00,0x00,0x00,0x00,0x00,0x00,0x0f,0xf0,0x00,0x00,0x00,0x00,0x00,0x00,0x07,0xf0,0x00,0x00,0x00,0x00,0x00,0x00,0x07,0xe0,0x00,0x00,0x00,0x00,0x00,0x00,0x07,0xe0,0x00,0x00,0x00,0x00,0x00,0x00,0x07,0xe0,0x00,0x00,0x00,0x00,0x00,0x00,0x07,0xf0,0x00,0x00,0x00,0x00,0x00,0x00,0x0f,0xf0,0x00,0x00,0x00,0x00,0x00,0x00,0x0f,0xf8,0x00,0x00,0x00,0x00,0x00,0x00,0x0f,0xfc,0x00,0x00,0x00,0x00,0x00,0x00,0x1f,0xff,0x00,0x00,0x00,0x00,0x00,0x0f,0xff,0xff,0xff,0x00,0x00,0x00,0x07,0xff,0xff,0xff,0xff,0xf0,0x00,0x00,0x0f,0xff,0xff,0xff,0xff,0xff,0x00,0x00,0x1f,0xff,0xff,0xff,0xff,0xff,0x00,0x00,0x1f,0xff,0xff,0xff,0xff,0xfc,0x00,0x00,0x01,0xbf,0xff,0xff,0xff,0x30,0x00,0x00,0x00,0x13,0xf7,0xb8,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00
    };
    display.drawBitmap(0, 0, imExp, 64, 62, 1); // draw mushroom cloud
}

void drawSkull() {
    // store image in EEPROM
    static const unsigned char PROGMEM imSku[] = {
       0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0xe0,0x00,0x00,0x00,0x00,0x30,0x00,0x00,0xf0,0x00,0x00,0x00,0x00,0x78,0x00,0x07,0xf0,0x00,0x00,0x00,0x00,0xfc,0x00,0x07,0xf8,0x00,0x00,0x00,0x00,0xfe,0x00,0x07,0xf8,0x00,0x00,0x00,0x01,0xfe,0x00,0x07,0xfc,0x00,0x00,0x00,0x01,0xfe,0x00,0x07,0xfe,0x00,0x3f,0xc0,0x03,0xfe,0x00,0x01,0xff,0x81,0xff,0xfc,0x07,0xec,0x00,0x00,0x3f,0xc7,0xff,0xff,0x1f,0xc0,0x00,0x00,0x0f,0xcf,0xff,0xff,0xdf,0x00,0x00,0x00,0x07,0xbf,0xff,0xff,0xee,0x00,0x00,0x00,0x01,0x7f,0xff,0xff,0xf0,0x00,0x00,0x00,0x00,0xff,0xff,0xff,0xf8,0x00,0x00,0x00,0x01,0xff,0xff,0xff,0xf8,0x00,0x00,0x00,0x03,0xff,0xff,0xff,0xfc,0x00,0x00,0x00,0x07,0xff,0xff,0xff,0xfe,0x00,0x00,0x00,0x0f,0xff,0xff,0xff,0xff,0x00,0x00,0x00,0x0f,0xff,0xff,0xff,0xff,0x00,0x00,0x00,0x1f,0xff,0xff,0xff,0xff,0x80,0x00,0x00,0x1f,0xff,0xff,0xff,0xff,0x80,0x00,0x00,0x1f,0xff,0xff,0xff,0xff,0x80,0x00,0x00,0x1f,0xff,0xff,0xff,0xff,0x80,0x00,0x00,0x1f,0xff,0xff,0xff,0xff,0x80,0x00,0x00,0x1f,0xff,0xff,0xff,0xff,0x80,0x00,0x00,0x1e,0x3f,0xff,0x3f,0xc7,0x80,0x00,0x00,0x1e,0x0c,0x0f,0x00,0x07,0x80,0x00,0x00,0x1e,0x00,0x0f,0x00,0x0f,0x80,0x00,0x00,0x1e,0x00,0x19,0x80,0x0f,0x00,0x00,0x00,0x0f,0x00,0x19,0x80,0x0f,0x00,0x00,0x00,0x0d,0x00,0x30,0xc0,0x1f,0x00,0x00,0x00,0x05,0x80,0x70,0xc0,0x1e,0x00,0x00,0x00,0x05,0xf0,0xe0,0xe0,0x36,0x00,0x00,0x00,0x01,0xff,0xe0,0x7f,0xf0,0x00,0x00,0x00,0x03,0xff,0xc4,0x7f,0xf0,0x00,0x00,0x00,0x03,0xff,0xcc,0x7f,0xf0,0x00,0x00,0x00,0x03,0xff,0xcc,0x7f,0xf0,0x00,0x00,0x00,0x03,0xff,0x9e,0x7f,0xf0,0x00,0x00,0x00,0x00,0xff,0xfe,0x7f,0xc0,0x00,0x00,0x00,0x00,0x01,0xff,0xf8,0x1c,0x00,0x00,0x00,0x03,0xe0,0x3f,0x01,0xbf,0x00,0x00,0x00,0x07,0xa6,0x40,0x09,0x9f,0x80,0x00,0x00,0x1f,0x27,0x5a,0x39,0x9f,0xf8,0x00,0x01,0xff,0x27,0xdb,0x39,0x0f,0xfc,0x00,0x03,0xfe,0x31,0x7f,0x39,0x07,0xfc,0x00,0x03,0xfc,0x10,0x1a,0x02,0x03,0xf8,0x00,0x03,0xf8,0x10,0x00,0x02,0x01,0xf0,0x00,0x01,0xf8,0x10,0x00,0x02,0x01,0xe0,0x00,0x00,0x78,0x10,0x00,0x02,0x00,0xe0,0x00,0x00,0x70,0x30,0x00,0x02,0x00,0x00,0x00,0x00,0x30,0x20,0x00,0x03,0x00,0x00,0x00,0x00,0x00,0x64,0x00,0x1b,0x00,0x00,0x00,0x00,0x00,0x73,0x55,0x63,0x00,0x00,0x00,0x00,0x00,0xf9,0x55,0x4f,0x00,0x00,0x00,0x00,0x00,0x7f,0x14,0x1f,0x00,0x00,0x00,0x00,0x00,0x1f,0xe0,0xfe,0x00,0x00,0x00,0x00,0x00,0x0f,0xff,0xfc,0x00,0x00,0x00,0x00,0x00,0x07,0xff,0xf0,0x00,0x00,0x00,0x00,0x00,0x03,0xff,0xc0,0x00,0x00,0x00,0x00,0x00,0x00,0x38,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00
    };
    display.drawBitmap(64, 0, imSku, 60, 64, 1); // draw skull cloud
}