Arduino Digital Tug of War

In this project, we’ll build a fun “Tug of War” game using an Arduino, a LED bar graph display, and buttons. The game mimics a classic tug-of-war, where two players compete to press their button rapidly to pull the “rope” (represented by a LED) to their side.

Contents

Components Needed

Arduino Uno (or similar) – 1
LED bar graph display (10-segment) – 1
Push buttons – 2
Resistors (10kΩ for pull-downs) – 2
Resistors (220Ω or 330Ω for LEDs) – 10
Breadboard – 1
Jumper wires

Wiring Diagram

Component	Arduino Pin	Notes
LED bar graph pins	D2–D11	Each pin controls one LED
Button 1	D12	Player 1’s button
Button 2	D13	Player 2’s button
10kΩ resistors	GND	Pull-down for buttons
220Ω resistors	Series with LEDs	Protect LEDs

LED Bar Graph:
- Connect the cathodes of the LEDs to GND through a 220Ω resistor.
- Connect each anode to Arduino pins D2 to D11.
Buttons:
- Connect one leg of each button to GND through a 10kΩ resistor (pull-down configuration).
- Connect the other leg to D12 (Player 1) and D13 (Player 2).

Gameplay Overview

A “marker” (one lit LED) starts in the middle of the LED bar graph.
Players press their respective buttons to move the marker toward their end.
The game ends when the marker reaches one side, indicating the winner.

Code

Here’s the Arduino sketch for the Tug of War game:

// Tug of War Game for Arduino

const int ledPins[] = {2, 3, 4, 5, 6, 7, 8, 9, 10, 11}; // LED pins
const int numLeds = 10; // Number of LEDs
const int button1Pin = 12; // Player 1 button
const int button2Pin = 13; // Player 2 button

int markerPosition = numLeds / 2; // Start in the middle

void setup() {
   // Initialize LED pins as output
   for (int i = 0; i < numLeds; i++) {
       pinMode(ledPins[i], OUTPUT);
   }

   // Initialize button pins as input
   pinMode(button1Pin, INPUT);
   pinMode(button2Pin, INPUT);

   // Light up the starting LED
   updateLeds();
}

void loop() {
   // Read button states
   int button1State = digitalRead(button1Pin);
   int button2State = digitalRead(button2Pin);

   // Check if Player 1 presses their button
   if (button1State == HIGH) {
      markerPosition = max(0, markerPosition - 1); // Move left
      updateLeds();
      delay(200); // Debounce delay
   }

   // Check if Player 2 presses their button
   if (button2State == HIGH) {
      markerPosition = min(numLeds - 1, markerPosition + 1); // Move right
      updateLeds();
      delay(200); // Debounce delay
   }

   // Check for win condition
   if (markerPosition == 0) {
      gameOver(1); // Player 1 wins
   } else if (markerPosition == numLeds - 1) {
      gameOver(2); // Player 2 wins
   }
}

void updateLeds() {
  for (int i = 0; i < numLeds; i++) {
     digitalWrite(ledPins[i], i == markerPosition ? HIGH : LOW);
  }
}


void gameOver(int winner) {
   for (int i = 0; i < 5; i++) {
   
      // Flash LEDs to indicate the winner
      for (int j = 0; j < numLeds; j++) {
         digitalWrite(ledPins[j], HIGH);
      }

      delay(200);
      for (int j = 0; j < numLeds; j++) {
         digitalWrite(ledPins[j], LOW);
      }

      delay(200);
   }

   // Display winner LED permanently
   if (winner == 1) {
      digitalWrite(ledPins[0], HIGH); // Player 1 wins
   } else {
      digitalWrite(ledPins[numLeds - 1], HIGH); // Player 2 wins
   }

   while (true) {} // Stop the game
}

Explanation

LED Control:
- The updateLeds() function ensures only one LED (the marker) is lit at any time, based on the markerPosition.
Button Handling:
- The loop checks if either button is pressed and adjusts the marker’s position accordingly.
- A debounce delay is added to prevent multiple detections from a single press.
Win Condition:
- If the marker reaches the first or last LED, the game ends, and the LEDs flash to indicate the winner.
Game Over:
- After flashing, the winner’s LED stays lit, and the game stops.