Setting Up the Arduino Firmware

Before using Ardulink-2 from Java, your Arduino board needs the Ardulink firmware. This firmware implements the Ardulink protocol, enabling communication between the Java library and the Arduino hardware.

Quick Upload: WebSerial Flasher

The fastest way to flash the firmware is the browser-based WebSerial Flasher — no software installation required.

  1. Open the WebSerial Flasher in Chrome or Edge (WebSerial support required)
  2. Click ↻ Latest to automatically fetch the latest firmware release
  3. Click Program
  4. When prompted, select your Arduino’s serial port
  5. Wait for the upload to complete — you’ll see a success message

If the WebSerial Flasher doesn’t work for your board, use one of the alternative methods below.

Alternative: Pre-compiled HEX Files

Download ready-to-flash .hex files from the Firmware Releases.

Available board variants:

  • Arduino Uno
  • Arduino Nano
  • Arduino Mega

Upload using one of these tools:

Tool Platform Notes
avrdude macOS/Linux/Windows Command-line, most reliable
XLoader Windows Simple GUI
Arduino IDE macOS/Linux/Windows Via sketch import

Using avrdude 

# For Arduino Uno
avrdude -p atmega328p -c arduino -P /dev/ttyACM0 -b 115200 -U flash:w:ArdulinkProtocol_uno.hex

# For Arduino Mega
avrdude -p atmega2560 -c wiring -P /dev/ttyACM0 -b 115200 -U flash:w:ArdulinkProtocol_mega.hex

Replace /dev/ttyACM0 with your actual serial port. On macOS it’s typically /dev/cu.usbmodem*, on Windows it’s COM3, COM4, etc.

Alternative: Build from Source

If you want to customize the firmware, build it from source:

  1. Install the Arduino IDE

  2. Clone the firmware repository:

    git clone https://github.com/Ardulink/Firmware.git
  3. Open Firmware/ArdulinkProtocol/ArdulinkProtocol.ino in the Arduino IDE
  4. Select your board under Tools > Board
  5. Select your serial port under Tools > Port
  6. Click Upload

Firmware Variants

The firmware repository includes different variants in the variants/ directory and pre-compiled in the examples/ directory. These may include:

  • Standard Ardulink Protocol — Default firmware for serial communication
  • NodeMCU variants — For ESP8266-based boards with Lua scripting
  • Custom examples — Demonstration sketches with additional functionality

What the Firmware Does

Once uploaded, the firmware:

  1. Listens for commands on the serial port (or other configured transport)
  2. Parses the Ardulink protocol messages
  3. Executes commands (set pins, read pins, play tones)
  4. Sends responses and events back to the Java side

The protocol supports:

  • Digital pin read/write
  • Analog pin read/write
  • PWM control
  • Tone generation
  • Custom message exchange
  • Pin change subscriptions

Protocol Specification

For full details on the communication protocol, see the Ardulink2 Specification.

Firmware Version

The current firmware release is v1.2.0 (February 2025).

Troubleshooting

Upload fails

  • Try a different USB cable (some are charge-only)
  • Make sure the correct board and port are selected
  • On Linux, check serial port permissions: sudo usermod -a -G dialout $USER
  • Press the reset button on the Arduino just before uploading

Firmware uploads but Java can’t connect

  • Verify the firmware is the Ardulink protocol firmware (not a blank sketch)
  • Check that the baud rate matches (default: 115200)
  • Ensure no other application is using the serial port

WebSerial Flasher not available

  • WebSerial requires Chrome 89+ or Edge 89+
  • Must be served over HTTPS (the GitHub Pages URL is fine)
  • Try a different browser if issues persist

Next Steps