Example project · Microcontrollers

Binary dice roller

CLICK AND HOLD THE BUTTON to spin the die, release to roll: three LEDs show the face 1 to 6 in binary and every roll is announced on the serial monitor. The result is human-timed (whichever face the 50 ms spin lands on when you let go), which is how fairground reaction games actually work. The Code tab holds the same game as an editable Arduino sketch.

Open this project in the simulator →All example projects

What's on the bench

3× LED
3× Resistor
Arduino Uno
Battery
Button

The code

This Arduino C++ sketch lives in the Code tab; sign in and press Compile & upload to build real firmware for the emulated board.

// The same dice game as an Arduino sketch. Edit it, then Compile &
// upload (sign-in needed): the server builds real AVR firmware.
const int BUTTON_PIN = 2;
const int BIT_PINS[3] = {8, 9, 10};  // 1s, 2s, 4s

int face = 0;  // 0..5

void show(int value) {  // value 1..6 in binary on the LEDs
  for (int b = 0; b < 3; b++) digitalWrite(BIT_PINS[b], (value >> b) & 1);
}

void setup() {
  for (int b = 0; b < 3; b++) pinMode(BIT_PINS[b], OUTPUT);
  pinMode(BUTTON_PIN, INPUT_PULLUP);  // the button closes to ground
  Serial.begin(9600);
  Serial.println("Hold the button to spin  release to roll");
}

void loop() {
  if (digitalRead(BUTTON_PIN) == LOW) {
    while (digitalRead(BUTTON_PIN) == LOW) {  // spinning while held
      face = (face + 1) % 6;
      show(face + 1);
      delay(50);
    }
    Serial.print("Rolled ");
    Serial.println(face + 1);
  }
  delay(10);
}