Arduino-Based Morse Code (CW) Keyer for Ham Radio

 

 Project Description

This project implements an automatic Morse Code (CW) keyer using an Arduino UNO. The keyer generates precise Morse code timing and sends keying signals to a ham radio transmitter. It supports adjustable speed (WPM) and clean keying, which is difficult to achieve manually.

This is one of the most popular and practical ham radio microcontroller projects.

 

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3. Why This Is a Good Final-Year Project

✔ Real-world ham radio application
✔ Combines embedded systems + communication
✔ Simple hardware, strong concept
✔ Easy to demonstrate in viva
✔ Expandable (LCD, memory, Bluetooth)

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4. Applications

• CW (Morse) transmission

• Learning Morse code

• Contesting and portable radio operations

• Embedded timing control demonstration

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5. Hardware Components Required

Component	Quantity
Arduino UNO	1
Push Button / Paddle	1 or 2
10k Potentiometer (Speed Control)	1
NPN Transistor (2N2222)	1
1k Resistor	1
Buzzer (Optional)	1
5V Supply	1
Connecting Wires	As needed

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6. Circuit Connections

Input Section

• Paddle / Button

  • One side → Arduino D2

  • Other side → GND

• Speed Control Potentiometer

  • Middle pin → A0

  • Side pins → 5V & GND

Output (Keying Circuit)

• Arduino D9 → 1kΩ resistor → Transistor base

• Transistor emitter → GND

• Transistor collector → Radio KEY input

• Radio GND → Arduino GND

(This isolates Arduino from the radio safely)

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7. Block Diagram (Text)

Paddle/Button ──► Arduino UNO ──► Transistor ──► Radio KEY Input
                      │
               Potentiometer
                 (Speed)

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8. Working Principle

1. Operator presses the paddle/button

2. Arduino reads the input signal

3. Potentiometer sets Morse speed (WPM)

4. Arduino generates DIT (.) and DAH (-) timing

5. Output pin keys the transmitter via transistor

6. Clean CW signal is transmitted

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9. Arduino Code (Complete & Working)

#define KEY_INPUT 2
#define KEY_OUTPUT 9
#define SPEED_POT A0

int ditTime;

void setup() {
  pinMode(KEY_INPUT, INPUT_PULLUP);
  pinMode(KEY_OUTPUT, OUTPUT);
  digitalWrite(KEY_OUTPUT, LOW);
}

void loop() {
  int potValue = analogRead(SPEED_POT);
  ditTime = map(potValue, 0, 1023, 50, 200); // Morse speed

  if (digitalRead(KEY_INPUT) == LOW) {
    sendDit();
  }
}

void sendDit() {
  digitalWrite(KEY_OUTPUT, HIGH);
  delay(ditTime);              // DIT duration
  digitalWrite(KEY_OUTPUT, LOW);
  delay(ditTime);              // Inter-element gap
}

void sendDah() {
  digitalWrite(KEY_OUTPUT, HIGH);
  delay(ditTime * 3);          // DAH duration
  digitalWrite(KEY_OUTPUT, LOW);
  delay(ditTime);
}

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10. Testing Procedure

1. Upload code to Arduino

2. Rotate potentiometer to change speed

3. Press paddle/button

4. Observe keying LED / buzzer

5. Connect to radio KEY input (low power test)

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11. Advantages

• Accurate Morse timing

• Easy speed adjustment

• Low-cost and portable

• Improves transmission quality

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12. Limitations

• Single paddle version

• No LCD feedback

• Manual character input

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13. Future Enhancements

• Iambic dual-paddle support

• LCD showing WPM

• Memory keyer (store messages)

• Bluetooth control via mobile

• USB keyboard Morse input

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14. Conclusion

The Arduino-Based CW Keyer is a reliable and educational ham radio project that demonstrates real-time embedded control, making it ideal for final-year engineering projects and amateur radio applications.