Arduino Project

Morse Code

Course Introduction

In this lesson, you’ll use a button, an LED, and a buzzer with the Arduino R4 UNO to create a simple Morse code trainer.

By pressing the button for short or long durations, you can input dots and dashes. The LED and buzzer provide immediate feedback, and the serial monitor displays whether you sent a dot (·) or a dash (—). This project is great for learning Morse code basics interactively.

Note

If this is your first time working with an Arduino project, we recommend downloading and reviewing the basic materials first.

1.1 Install Arduino IDE(Important)
1.2 Introduction of Arduino IDE

Required Components

In this project, we need the following components:

SN

COMPONENT INTRODUCTION

QUANTITY

PURCHASE LINK

1

Arduino UNO R4 Minima

1

BUY

2

USB Type-C cable

1

×

3

Breadboard

1

BUY

4

Wires

Several

BUY

5

Passive Buzzer

1

BUY

6

Button

1

BUY

7

LED

1

BUY

8

1kΩ resistor

1

BUY

Wiring

Morse_Code_bb.webp__PID:fbf56b14-618b-44e6-a857-fa1b6dc856af

Common Connections:

LED
Connect the LED to a 1kΩ resistor, then to anode to 3 on the Arduino, and the cathode to the negative power bus on the breadboard.

Passive Buzzer
＋: Connect to 2 on the Arduino.
－: Connect to breadboard’s negative power bus.

Button
Connect to the breadboard’s negative power bus, and the other end to 4 on the Arduino board.

Writing the Code

Note
You can copy this code into the Arduino IDE.
Don’t forget to select the board(Arduino UNO R4 Minima) and the correct port before clicking the Upload button.


// Pin Definitions
const int BUTTON_PIN = 4;   // Push button (connect to GND)
const int BUZZER_PIN = 2;   // Active buzzer (+)
const int LED_PIN = 3;      // LED anode (with 220Ω resistor)

// Timing Constants (milliseconds)
const int DOT_DURATION = 200;   // Standard dot duration
const int DASH_DURATION = 600;  // Standard dash duration
const int DEBOUNCE_DELAY = 50;  // Button debounce time

// Global Variables
bool lastButtonState = HIGH;    // Track previous button state
unsigned long pressStartTime = 0; // Timing variable

void setup() {
  // Initialize pins
  pinMode(BUTTON_PIN, INPUT_PULLUP); // Internal pull-up
  pinMode(LED_PIN, OUTPUT);
  pinMode(BUZZER_PIN, OUTPUT);

  // Ensure outputs start OFF
  digitalWrite(LED_PIN, LOW);
  digitalWrite(BUZZER_PIN, LOW);

  // Start serial communication
  Serial.begin(9600);
  Serial.println("Morse Code Trainer Ready");
  Serial.println("Short press: Dot(·)  Long press: Dash(—)");
}

void loop() {
  int currentButtonState = digitalRead(BUTTON_PIN);

  // Handle button press (active LOW)
  if (currentButtonState == LOW && lastButtonState == HIGH) {
    delay(DEBOUNCE_DELAY); // Debounce
    if (digitalRead(BUTTON_PIN) == LOW) { // Confirmed press
      pressStartTime = millis(); // Record start time
      activateFeedback(); // Turn on LED and buzzer
      Serial.println("Button PRESSED");
    }
  }

  // Handle button release
  if (currentButtonState == HIGH && lastButtonState == LOW) {
    delay(DEBOUNCE_DELAY);
    if (digitalRead(BUTTON_PIN) == HIGH) { // Confirmed release
      deactivateFeedback(); // Turn off immediately
      handleMorseSymbol(); // Process the symbol
    }
  }

  lastButtonState = currentButtonState; // Update state
}

// Turn on both visual and audio feedback
void activateFeedback() {
  digitalWrite(LED_PIN, HIGH);
  digitalWrite(BUZZER_PIN, HIGH);
}

// Turn off both feedback channels
void deactivateFeedback() {
  digitalWrite(LED_PIN, LOW);
  digitalWrite(BUZZER_PIN, LOW);
}

// Determine if it's a dot or dash
void handleMorseSymbol() {
  unsigned long pressDuration = millis() - pressStartTime;

  if (pressDuration < DASH_DURATION) {
    Serial.println("Sent: DOT(·)");
    // Ensure minimum dot duration
    if (pressDuration < DOT_DURATION) {
      delay(DOT_DURATION - pressDuration);
    }
  } else {
    Serial.println("Sent: DASH(—)");
    // Ensure minimum dash duration
    if (pressDuration < DASH_DURATION) {
      delay(DASH_DURATION - pressDuration);
    }
  }
}