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Arduino
Brain
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Dice Simulator
variables plus random for dice
Roll a die 1–6 with random() stored in a variable when you press a button.
Pin connections
| Part 1 | Part 2 | |
|---|---|---|
Pushbutton pin 1 | → | Arduino pin 2 |
Pushbutton pin 2 | → | Arduino GND |
See it
Roll the dice!
Press the button — lastRoll stores random(1, 7) for a fresh 1–6 each time.
Board games and apps store the latest roll in a variable before showing it.
The story
The problem
You want a die face that changes only when the player asks to roll.
Think of it like
Like shaking a dice cup — the number stays until you roll again.
Meet the parts
How it works
1
Wait for roll button
Nothing changes until you press — lastRoll keeps the previous value.
if (digitalRead(BUTTON_PIN) == LOW)
2
Pick random die face
random(1, 7) gives 1 through 6 — stored in lastRoll until the next roll.
lastRoll = random(1, 7);
3
Show result
Print the stored roll, debounce the button, then loop() waits again.
Serial.print("You rolled: ");
Serial.println(lastRoll);Then loop back to step 1
Build the circuit
Follow these steps in order. Match the wires to the colors shown.
- 1
Place Arduino
Place the Arduino (uno) on the breadboard.
Arduino placed!
Loading part…
Try it
- Press the button — You rolled: 1–6 on Serial.
- Press again for a new random face!
Peek at code
lastRoll variable
const int BUTTON_PIN = 2; int lastRoll = 1;
lastRoll remembers the most recent die face between button presses.
Setup and seed
pinMode(BUTTON_PIN, INPUT_PULLUP);
Serial.begin(9600);
randomSeed(analogRead(0));
Serial.println("Dice — press button to roll");
}Button pin, Serial, and randomSeed() prepare for fair rolls.
Roll on press
lastRoll = random(1, 7);
Serial.print("You rolled: ");
Serial.println(lastRoll);
while (digitalRead(BUTTON_PIN) == LOW) {
delay(20);
}
delay(200);
}
delay(20);
}
Press → random roll → store in lastRoll → print → wait for next press.
Show full sketch (dice-simulator.ino)
const int BUTTON_PIN = 2;
int lastRoll = 1;
void setup() {
pinMode(BUTTON_PIN, INPUT_PULLUP);
Serial.begin(9600);
randomSeed(analogRead(0));
Serial.println("Dice — press button to roll");
}
void loop() {
if (digitalRead(BUTTON_PIN) == LOW) {
lastRoll = random(1, 7);
Serial.print("You rolled: ");
Serial.println(lastRoll);
while (digitalRead(BUTTON_PIN) == LOW) {
delay(20);
}
delay(200);
}
delay(20);
}
Quick quiz
Q1. What is a variable?
- A. A named place to store a value ✓
- B. A type of wire
- C. Only delay()
Why: Correct — int score = 0; creates a box named score.
Q2. What does random(1, 7) return?
- A. 1 to 6 inclusive ✓
- B. 1 to 7 inclusive
- C. Always 1
Why: Correct — you get 1, 2, 3, 4, 5, or 6 — perfect for a die.
Code lab — try on your own
Pretend last roll was 6 — change int lastRoll = 1 to int lastRoll = 6.
Hint: Line 2.
Add a comment on lastRoll = random(1, 7) explaining “new die face”.
Hint: Line 13 inside the if block.
Code walkthrough
A line-by-line tour of the sketch — the same steps as in Robo Gurukul Studio.
Program overview
Technical
Sketches have globals, then setup() once, then loop() forever.
In this project
Roll a die 1–6 with random() stored in a variable when you press a button.
Why here
Read from top to bottom. Hover words or lines for help!
const int BUTTON_PIN = 2; int lastRoll = 1;
setup()
Technical
Runs one time when the board turns on.
In this project
Sets up pins and libraries for Dice Simulator.
Why here
One-time setup belongs here—not in loop().
void setup() {
pinMode(BUTTON_PIN, INPUT_PULLUP);
Serial.begin(9600);
randomSeed(analogRead(0));
Serial.println("Dice — press button to roll");
}loop()
Technical
Runs again and again after setup() is done.
In this project
This is the main action you see in Dice Simulator.
Why here
Repeating work (blink, read sensors) goes here.
void loop() {
if (digitalRead(BUTTON_PIN) == LOW) {
lastRoll = random(1, 7);
Serial.print("You rolled: ");
Serial.println(lastRoll);
while (digitalRead(BUTTON_PIN) == LOW) {
delay(20);
}
delay(200);
}
delay(20);
}
Try this: Change numbers in loop(), then compile and run the simulator.
pinMode
Technical
Tells a pin if it listens or drives something.
In this project
Gets the Dice Simulator circuit ready in the simulator.
Why here
Goes in setup() because we only set pins once at the start.
pinMode(BUTTON_PIN, INPUT_PULLUP);
digitalRead
Technical
Checks if a pin is ON or OFF.
In this project
Reads buttons or sensors in Dice Simulator.
Why here
Goes in loop() so we can react when something changes.
if (digitalRead(BUTTON_PIN) == LOW) {analogRead
Technical
Reads a sensor number from 0 to 1023.
In this project
Turns a sensor signal into a number for Dice Simulator.
Why here
Goes in loop() to keep checking the sensor.
randomSeed(analogRead(0));
delay
Technical
Waits for some time. Nothing else runs during the wait.
In this project
Controls speed so you can see Dice Simulator in the simulator.
Why here
Right after an action that should stay the same for a moment.
delay(20);
random
Technical
Picks a random number in a range.
In this project
Adds randomness in Dice Simulator.
Why here
In loop() when you want different values each time.
lastRoll = random(1, 7);
begin
Technical
Starts talking to the computer screen (serial monitor).
In this project
Lets Dice Simulator print debug messages.
Why here
Goes in setup() once before any Serial.print.
Serial.begin(9600);
Technical
Sends text to the serial monitor without a new line.
In this project
Shows values from Dice Simulator on the screen.
Why here
In loop() or setup() when you want to see what the board is doing.
Serial.print("You rolled: ");println
Technical
Sends text to the serial monitor and starts a new line.
In this project
Prints one line of output for Dice Simulator.
Why here
In loop() when each reading should appear on its own line.
Serial.println("Dice — press button to roll");