const int leds[4] = {4, 5, 6, 7};

• Defines an array containing the digital pin numbers for the 4 LEDs. Each index corresponds to one LED.

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const int buttons[4] = {8, 9, 10, 11};

• Defines an array with the pin numbers for the 4 buttons, each paired with an LED by index.

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const int buzzer = 3;

• Assigns pin 3 to the buzzer. This will be used to output tones during the game.

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int sequence[100];

• Creates an array to store up to 100 values representing the LED sequence the player must remember.

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int level = 0;

• Keeps track of the current game level (or sequence length). Starts at 0 and increases as the player succeeds.

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void setup() {

• Starts the setup section, which runs once when the Arduino powers on or resets.

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for (int i = 0; i < 4; i++) { pinMode(leds[i], OUTPUT); pinMode(buttons[i], INPUT); }

• Loops through all 4 LEDs and buttons, setting the LED pins as OUTPUT and button pins as INPUT (for reading presses).

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pinMode(buzzer, OUTPUT);

• Sets the buzzer pin as an output so tones can be played.

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randomSeed(analogRead(0));
Seeds the random number generator using noise from analog pin 0 for better randomness.

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nextRound();

• Calls the function to start the first round and generate the first LED in the sequence.

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void loop() {

• Begins the main game loop, which runs continuously.

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if (!playSequence()) { gameOver(); nextRound(); }

• Plays the current sequence. If the player gets it wrong, the game over sequence plays and a new game starts.

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delay(500);

• Pauses for half a second between rounds.

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level++;

• Increases the level after a successful round.

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sequence[level] = random(0, 4);

• Adds a new random LED to the sequence, choosing a number from 0 to 3 (representing the 4 LEDs).

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bool playSequence() {

• Starts a function that plays the sequence and checks player input.

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for (int i = 0; i <= level; i++) { lightLED(sequence[i]); delay(250); clearLEDs(); delay(250); }

• Loops through the sequence, lights each LED briefly, and clears it to show the pattern to the player.

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for (int i = 0; i <= level; i++) { int guess = waitForButton(); if (guess != sequence[i]) { return false; } }

• Waits for player input, one button at a time. If any input doesn’t match the stored sequence, the function returns false (indicating a mistake).

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return true;

• If the player completed the whole sequence correctly, return true.

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int waitForButton() {

• Starts a function that waits until one of the buttons is pressed.

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while (true) { for (int i = 0; i < 4; i++) { if (digitalRead(buttons[i]) == HIGH) {

• Loops forever until any one of the 4 buttons reads HIGH (pressed).

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lightLED(i); delay(200); clearLEDs();

• Lights the matching LED for feedback and clears it shortly after.

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while (digitalRead(buttons[i]) == HIGH);

• Waits until the player releases the button (prevents multiple counts from one press).

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return i;

• Returns the index of the button that was pressed.

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void lightLED(int i) {

• Lights up the LED at index i and plays a tone based on its index.

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digitalWrite(leds[i], HIGH);

• Turns on the selected LED.

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tone(buzzer, 200 + i * 100, 150);

• Plays a short tone using the buzzer. The frequency depends on which LED is lit.

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void clearLEDs() {

• Turns off all the LEDs.

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for (int i = 0; i < 4; i++) { digitalWrite(leds[i], LOW); }

• Loops through all LED pins and turns them off.

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void gameOver() {

• Plays a game over pattern of lights and sound.

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for (int i = 0; i < 3; i++) { for (int j = 0; j < 4; j++) { digitalWrite(leds[j], HIGH); }

• Flashes all LEDs on.

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tone(buzzer, 200, 300); delay(300); clearLEDs(); delay(300); }

• Plays a low tone, waits, turns off LEDs, and pauses briefly — repeated 3 times.

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level = 0;

• Resets the level to start a new game.

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void nextRound() {

• Prepares for the next game session or restarts the first round.

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sequence[0] = random(0, 4);

• Creates the first item in the new LED sequence.

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level = 0;

• Sets the level back to zero.