Digital dice on a 74HC595 (pins 11, 8 and 12), on an Arduino Uno

// Digital dice: the digit spins, press the button and it stops on a roll.
//
//   74HC595 DS -> pin 11   SH_CP -> pin 8   ST_CP -> pin 12
//   Q0 to Q6 -> segments a to g; the common cathode -> 220 ohm -> GND
//   button: one side -> 5V, the other -> pin 2 and 10k to GND
//   the Uno's own LED on pin 13 lights while the dice settles
//
// The digit flicks through 1 to 6 quickly. A press makes each step a little
// slower until it stops; random() picks every number, so the stop is fair.

const int DS = 11;
const int SHCP = 8;
const int STCP = 12;
const int BUTTON = 2;
const int LED = 13;

//                      gfedcba
const byte PATTERNS[7] = {0x3F, 0x06, 0x5B, 0x4F, 0x66, 0x6D, 0x7D};

void show(int n) {
  digitalWrite(STCP, LOW);
  shiftOut(DS, SHCP, MSBFIRST, PATTERNS[n]);
  digitalWrite(STCP, HIGH);
}

void setup() {
  pinMode(DS, OUTPUT);
  pinMode(SHCP, OUTPUT);
  pinMode(STCP, OUTPUT);
  pinMode(BUTTON, INPUT);
  pinMode(LED, OUTPUT);
  randomSeed(analogRead(A0));
  Serial.begin(9600);
  Serial.println("Mokxi Uno: digital dice. Press the button on pin 2 to roll.");
}

void loop() {
  show(random(1, 7));
  delay(60);
  if (digitalRead(BUTTON) == HIGH) {
    digitalWrite(LED, HIGH);
    int n = 1;
    for (int wait = 60; wait < 400; wait += 40) {
      n = random(1, 7);
      show(n);
      delay(wait);
    }
    digitalWrite(LED, LOW);
    Serial.print("rolled a ");
    Serial.println(n);
    while (digitalRead(BUTTON) == HIGH) {
    }
    delay(1500);
  }
}