Sending Tones and Key Events

Ardulink-2 can play tones through Arduino’s piezo buzzer and simulate keyboard events — useful for audio feedback and HID-like interactions.

Playing Tones

Basic Tone 

import org.ardulink.core.Link;
import org.ardulink.core.pin.Pin;
import org.ardulink.core.pin.Pin.AnalogPin;
import org.ardulink.core.Tone;
import org.ardulink.core.convenience.Links;

public class ToneExample {
    public static void main(String... args) throws Exception {
        try (Link link = Links.getDefault()) {
            AnalogPin pin = Pin.analogPin(8);  // Piezo buzzer on pin 8

            // Play a 440Hz tone (A4) for 200ms
            Tone tone = new Tone(pin, 440, 200);
            link.sendTone(tone);

            Thread.sleep(300);

            // Play a different frequency
            link.sendTone(new Tone(pin, 880, 200));

            Thread.sleep(300);

            // Stop the tone
            link.sendNoTone(pin);
        }
    }
}

Tone Parameters

The Tone class takes:

  • Pin — The analog pin connected to the buzzer
  • Frequency — Tone frequency in Hz (e.g., 440 for A4, 880 for A5)
  • Duration — How long to play in milliseconds

Common Frequencies

Note Hz Note Hz
C4 262 C5 523
D4 294 D5 587
E4 330 E5 659
F4 349 F5 698
G4 392 G5 784
A4 440 A5 880
B4 494 B5 988

Melody Example 

AnalogPin buzzer = Pin.analogPin(8);

int[] notes = {262, 294, 330, 349, 392, 440, 494, 523};
int[] durations = {200, 200, 200, 200, 200, 200, 200, 400};

for (int i = 0; i < notes.length; i++) {
    link.sendTone(new Tone(buzzer, notes[i], durations[i]));
    Thread.sleep(durations[i] + 50);
}

link.sendNoTone(buzzer);

Sending Key Press Events

Ardulink-2 can simulate keyboard events on the Arduino side:

import org.ardulink.core.Link;
import org.ardulink.core.convenience.Links;

public class KeyEventExample {
    public static void main(String... args) throws Exception {
        try (Link link = Links.getDefault()) {
            // Send key press: character, keycode, key location, modifiers, modifier extras
            link.sendKeyPressEvent('a', 65, 0, 0, 0);  // 'a' key
            Thread.sleep(100);
            link.sendKeyPressEvent('b', 66, 0, 0, 0);  // 'b' key
            Thread.sleep(100);

            // Ctrl+C (modifiers)
            link.sendKeyPressEvent('c', 67, 0, 2, 0);  // Ctrl=2
        }
    }
}

Key Event Parameters

Parameter Description
keychar The character value
keycode Virtual key code
keylocation Key location (0=standard, 3=numpad)
keymodifiers Modifier mask (1=Shift, 2=Ctrl, 4=Alt)
keymodifiersex Extended modifiers

Use Cases

  • Audio feedback — Beep when a button is pressed, play melodies for alerts
  • HID emulation — Simulate keyboard input to control connected displays or other devices
  • Interactive installations — Sound and input in art/education projects
  • Game controllers — Combine tones with button reads for interactive games

Next Steps