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How the generator works
The sketch reads characters, finds each letter or number in a Morse lookup table, then switches the output on and off according to that character’s dot-and-dash sequence. A dot lasts one timing unit; a dash lasts three. The output pauses briefly between symbols, longer between characters, and longest between words.
Arduino’s Morse Code Project demonstrates the one-LED approach. Its wiring guidance emphasizes that the output pin in the sketch must match the pin connected to the LED.
Parts and wiring
- Arduino-compatible board and USB cable
- One LED
- 220-ohm resistor
- Breadboard and jumper wires
- Optional piezo buzzer for audio output
- Connect the LED’s longer anode leg to a digital output pin, such as pin 13.
- Connect the shorter cathode leg through the 220-ohm resistor to GND.
- If adding a buzzer, connect it to a digital pin supported by the sketch; the example below uses pin 9.
- Check that the pin numbers in the sketch match your actual wiring before uploading.
Upload a text-to-Morse sketch
Install Arduino IDE, connect the board, and select the matching board and serial port. The following implementation pattern uses arrays for A–Z and 0–9. Pin 13, pin 9, and the 700 Hz tone are example choices, not guarantees that every board or buzzer will behave identically.
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const int ledPin = 13;
const int buzzerPin = 9;
const int dotDelay = 200;
const char* letters[] = {
".-", "-...", "-.-.", "-..", ".", "..-.", "--.", "....", "..",
".---", "-.-", ".-..", "--", "-.", "---", ".--.", "--.-", ".-.",
"...", "-", "..-", "...-", ".--", "-..-", "-.--", "--.."
};
const char* numbers[] = {
"-----", ".----", "..---", "...--", "....-",
".....", "-....", "--...", "---..", "----."
};
void flashSymbol(char symbol) {
digitalWrite(ledPin, HIGH);
if (buzzerPin >= 0) tone(buzzerPin, 700);
delay(symbol == '.' ? dotDelay : 3 * dotDelay);
digitalWrite(ledPin, LOW);
if (buzzerPin >= 0) noTone(buzzerPin);
delay(dotDelay);
}
void setup() {
pinMode(ledPin, OUTPUT);
pinMode(buzzerPin, OUTPUT);
Serial.begin(9600);
}
void loop() {
if (!Serial.available()) return;
char ch = Serial.read();
if (ch >= 'a' && ch <= 'z') ch -= 'a' - 'A';
if (ch == ' ') {
delay(4 * dotDelay);
return;
}
const char* code = nullptr;
if (ch >= 'A' && ch <= 'Z') code = letters[ch - 'A'];
else if (ch >= '0' && ch <= '9') code = numbers[ch - '0'];
else return; // Ignore unsupported characters
for (const char* p = code; *p; ++p) flashSymbol(*p);
delay(2 * dotDelay); // Character gap, including the final symbol gap
}Set the Serial Monitor to 9600 baud to match Serial.begin(9600). The dotDelay value controls the speed: reducing it makes the sequence faster; increasing it makes the flashes easier to follow. This sketch ignores punctuation that is not explicitly mapped.
Test and troubleshoot the output
- Upload a basic blink sketch first to confirm the board and LED circuit work.
- Upload the Morse sketch and enter
Sin the Serial Monitor. The LED should flash three short times for.... - Enter
O; the LED should produce three long flashes for---. - Try a word with a space to check that the sketch pauses between words.
- If the LED stays dark, check its polarity, the ground connection, and that the wired pin matches
ledPin. - If the sequence is too fast or slow, adjust
dotDelay. Add and troubleshoot the buzzer only after the LED output is reliable.
Ways to expand the project
Add a buzzer
A piezo buzzer can play a tone during each LED flash; Arduino’s Morse Code Project and a SunFounder R4 UNO lesson describe buzzer-based output. The sketch’s tone frequency is an example setting, so adjust it to suit the buzzer and board.
Rank #2
- Morse code experiment kit for use in teaching principles of the telegraph
- Includes D-cell battery holder, telegraph key, lamp with holder, and three connector cords
- Package Dimensions: 6.858 L x 14.224H x13.97W x(centimeters)
- Country Of Origin: United States
Use a button as a Morse key
A button-based trainer reverses the input direction: measure how long the button is held, treat a short press as a dot and a long press as a dash, then display or report the interpreted symbol. SunFounder’s R4 UNO lesson uses a button, LED, and buzzer and reports the interpreted dot or dash in Serial Monitor.
Add an LCD or keyboard
For a standalone text-to-Morse unit, a keyboard can supply text and an LCD can show characters while the LED or buzzer outputs Morse. Arduino Project Hub examples include a Nano with a 128x64 LCD and PS/2 keyboard, and an Uno Rev3 build with a 16x2 LCD that encodes serial messages while displaying characters. A simpler LCD-and-button build is also described in the Arduino forum. These additions increase wiring complexity and may require extra libraries.
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Quick Recap
Best Value
- Compatible Brand:Universal
- Custom Bundle:Regular
- Compatible Model:Universal
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Rank #3
- Kit Contents: Includes all necessary components for assembly, offering hands-on experience with electronic components and soldering
- Learning Tool: Practice Morse code communication while developing essential soldering skills through practical assembly
- Project Components: Features a custom PCB board, electronic parts, and protective enclosure for a complete build experience
- Skill Development: Build confidence in component identification, circuit assembly, and basic electronics principles
- Educational Value: Learn about electronic communication methods while gaining practical experience in circuit construction
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