Wiring the Circuit 

To wire the mini F1 Reaction game circuit, I followed these steps:

1. Power Rails Setup

• Connected the Arduino’s 5V pin to the positive rail (+) of the breadboard.
  
  

• Connected the GND pin to the negative rail (–) to provide a common ground for all components.
  
  

2. Connecting the LCD (I2C)

• Connected the VCC pin of the LCD module to the +5V rail and the GND pin to the ground rail.
  
  

• Connected the SDA pin of the LCD to Arduino A4 and the SCL pin to Arduino A5 (these are the I2C communication lines).
  
  

3. Connecting the Buttons

• Placed three push buttons on the breadboard: one for Start, one for Player 1, and one for Player 2.
  
  

• Connected one side of each button to Arduino pins 2, 3, and 4, respectively.
  
  

• Connected the other side of each button to the ground rail (–).
  
  

• Enabled internal pull-up resistors in the code (using INPUT_PULLUP), so no external resistors were needed.
  
  

4. Connecting the LEDs

• Placed three LEDs: green (start indicator) on pin 5, red (Player 1) on pin 6, and red (Player 2) on pin 7.
  
  

• Connected each LED’s positive (long) leg to its assigned pin through a 220Ω resistor to limit current.
  
  

• Connected each LED’s negative (short) leg to the ground rail (–).
  
  

5. Final Check

• Verified all connections were secure, ensuring no loose wires or short circuits.
  
  

• Powered the Arduino through USB to test the circuit.

The Code

🧩 Block 1 — Libraries and LCD Setup

#include <Wire.h>                 

#include <LiquidCrystal_I2C.h>    

LiquidCrystal_I2C lcd(0x27, 16, 2);

What it does:

• Adds the libraries needed to communicate with the LCD through I2C (which uses only 2 Arduino pins).
  
  

• Creates an lcd object with the I2C address 0x27, 16 columns, and 2 rows.
  
  

This allows you to display messages on the LCD screen.

🧩 Block 2 — Pin Assignments

const int startButton = 2;

const int player1Button = 3;

const int player2Button = 4;

const int greenLED = 5;

const int player1LED = 6;

const int player2LED = 7;

What it does:

• Assigns names to each input/output pin.
  
  

• Using const int ensures these pin numbers never change during the program.
  
  

Inputs: Start button, Player1 button, Player2 button
Outputs: Green LED, Player1 LED, Player2 LED

🧩 Block 3 — Game State Variables

bool gameRunning = false;

int startTime = 0;

bool winnerDeclared = false;

What it does:

• gameRunning: Tracks whether the game has started.
  
  

• startTime: Stores the time (in ms) when the “GO” signal appears to measure reaction time.
  
  

• winnerDeclared: Makes sure only the first button press counts as the winner.
  
  

🧩 Block 4 — setup() Function

void setup() {

  pinMode(startButton, INPUT_PULLUP);

  pinMode(player1Button, INPUT_PULLUP);

  pinMode(player2Button, INPUT_PULLUP);

  pinMode(greenLED, OUTPUT);

  pinMode(player1LED, OUTPUT);

  pinMode(player2LED, OUTPUT);

  lcd.init();

  lcd.backlight();

  lcd.setCursor(0, 0);

  lcd.print("F1 Reaction Game");

  lcd.setCursor(0, 1);

  lcd.print("Press Start!");

}

What it does:

• Configures the pins as inputs (buttons) or outputs (LEDs).
  
  

• Initializes and turns on the LCD.
  
  

• Shows a welcome message when the Arduino powers up.
  
  

🧩 Block 5 — loop() Function (Main Logic)

void loop() {

  if (!gameRunning && digitalRead(startButton) == LOW) {

    startGame();

  }

  if (gameRunning && !winnerDeclared) {

    checkWinner();

  }

}

What it does:

• Continuously checks if the start button is pressed → starts the game.
  
  

• If the game is running and no winner yet → checks who presses their button first.
  
  

🧩 Block 6 — startGame() Function

void startGame() {

  gameRunning = true;

  winnerDeclared = false;

  digitalWrite(player1LED, LOW);

  digitalWrite(player2LED, LOW);

  lcd.clear();

  lcd.setCursor(0, 0);

  lcd.print("Get Ready...");

  delay(1000);

  digitalWrite(greenLED, HIGH);

  for (int i = 1; i <= 3; i++) {

    lcd.clear();

    lcd.setCursor(0, 0);

    lcd.print("Countdown:");

    lcd.setCursor(0, 1);

    lcd.print(i);

    delay(1000);

  }

  digitalWrite(greenLED, LOW);

  lcd.clear();

  lcd.setCursor(0, 0);

  lcd.print("GO!");

  lcd.setCursor(0, 1);

  lcd.print("Press Button!");

  startTime = millis();

}

What it does:

• Starts the game, resets LEDs, and displays “Get Ready” then a countdown on the LCD.

• Green LED stays on during the countdown.

• Shows “GO!” then starts the reaction timer.

🧩 Block 7 — checkWinner() Function

void checkWinner() {

  if (digitalRead(player1Button) == LOW) {

    declareWinner(1);

  } else if (digitalRead(player2Button) == LOW) {

    declareWinner(2);

  }

}

What it does:

• Checks which player pressed their button first.

• Calls declareWinner() and sends the player number.
  
  

🧩 Block 8 — declareWinner() Function

void declareWinner(int player) {

  winnerDeclared = true;

  gameRunning = false;

  int reactionTime = millis() - startTime;

  lcd.clear();

  lcd.setCursor(0, 0);

  lcd.print("Player ");

  lcd.print(player);

  lcd.print(" Wins!");

  lcd.setCursor(0, 1);

  lcd.print("Time: ");

  lcd.print(reactionTime);

  lcd.print(" ms");

  if (player == 1) {

    digitalWrite(player1LED, HIGH);

  } else {

    digitalWrite(player2LED, HIGH);

  }

}

What it does:

• Stops the game and records reaction time.
  
  

• Displays the winner and their time on the LCD.
  
  

• Lights up the winner’s LED.