Eid greeting card on an Arduino Uno

// Eid greeting card: an LCD with a little crescent and star drawn on it
// that says Eid Mubarak, and a button that turns to the same wish in other
// languages Muslims around the world use.
//
//   LCD       16x2 with an I2C backpack: SDA -> A4, SCL -> A5
//   button    pin 2 -> button -> GND        (INPUT_PULLUP)
//   lamp      pin 5 -> 220 ohms -> yellow LED -> GND, a warm glow
//
// Eid Mubarak means "blessed Eid" in Arabic and is said everywhere. The card
// also has Eid Saeed (Arabic, "happy Eid"), Selamat Hari Raya (Malay and
// Indonesian, "happy day of celebration"), Barka da Sallah (Hausa, spoken in
// Nigeria and Niger) and Ciid Wanaagsan (Somali, "happy Eid").
//
// The crescent and the star are custom characters. A 16x2 LCD lets a sketch
// draw eight of its own, each 5 dots wide and 8 tall, one byte per row.
//
// Things to try. Press the button. Add your family's own greeting to
// GREETINGS: the wish, a second line if it is long, and the language.

#include <Wire.h>
#include <LiquidCrystal_I2C.h>

const int BUTTON_PIN = 2;
const int LAMP_PIN = 5;

LiquidCrystal_I2C lcd(0x27, 16, 2);

const uint8_t CRESCENT[8] = {0b00110, 0b01100, 0b11000, 0b11000, 0b11000, 0b01100, 0b00110, 0b00000};
const uint8_t STAR[8] = {0b00100, 0b00100, 0b11111, 0b01110, 0b01010, 0b10001, 0b00000, 0b00000};

// The wish, a second line if it needs one, and the language.
const char *GREETINGS[][3] = {
  {"Eid Mubarak", "", "Arabic"},
  {"Eid Saeed", "", "Arabic"},
  {"Selamat Hari", "Raya", "Malay"},
  {"Barka da Sallah", "", "Hausa"},
  {"Ciid Wanaagsan", "", "Somali"},
};
const int COUNT = sizeof(GREETINGS) / sizeof(GREETINGS[0]);

int shown = 0;

void show(int n) {
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print(GREETINGS[n][0]);
  lcd.setCursor(0, 1);
  lcd.print(GREETINGS[n][1][0] ? GREETINGS[n][1] : GREETINGS[n][2]);
  lcd.setCursor(14, 1);
  lcd.write(0);   // the crescent
  lcd.write(1);   // the star
  Serial.print(GREETINGS[n][0]);
  if (GREETINGS[n][1][0]) {
    Serial.print(" ");
    Serial.print(GREETINGS[n][1]);
  }
  Serial.print(" (");
  Serial.print(GREETINGS[n][2]);
  Serial.println(")");
}

void setup() {
  Serial.begin(9600);
  pinMode(BUTTON_PIN, INPUT_PULLUP);
  pinMode(LAMP_PIN, OUTPUT);
  lcd.init();
  lcd.backlight();
  lcd.createChar(0, CRESCENT);
  lcd.createChar(1, STAR);
  analogWrite(LAMP_PIN, 120);
  show(0);
}

void loop() {
  if (digitalRead(BUTTON_PIN) == LOW) {
    shown = (shown + 1) % COUNT;
    show(shown);
    while (digitalRead(BUTTON_PIN) == LOW) delay(10);
    delay(50);
  }
  // A slow breathing glow on the lamp.
  int t = (millis() / 8) % 512;
  analogWrite(LAMP_PIN, 60 + (t < 256 ? t : 511 - t) / 2);
  delay(10);
}