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firmata4j is a client library of Firmata written in Java. The library allows controlling Arduino (or another board) which runs Firmata protocol from your java program.

• Interaction with a board and its pins in object-oriented style
• Abstraction over details of the protocol
• Provides an UI component that visualize the current state of every pin and allows changing a mode and state of each of those

Add the following dependency to pom.xml of your project:

<dependency>
    <groupId>com.github.kurbatov</groupId>
    <artifactId>firmata4j</artifactId>
    <version>2.3.2</version>
</dependency>

General scenario of usage is following:

IODevice device = new FirmataDevice("/dev/ttyUSB0"); // construct the Firmata device instance using the name of a port
device.start(); // initiate communication to the device
device.ensureInitializationIsDone(); // wait for initialization is done
// do actual work here
device.stop(); // stop communication to the device

The "actual work" consists in sending commands to the board and processing events that occur on it.

To react to events we have to subscribe listeners of the device or its pins.

device.addEventListener(new IODeviceEventListener() {
    @Override
    public void onStart(IOEvent event) {
        // since this moment we are sure that the device is initialized
        // so we can hide initialization spinners and begin doing cool stuff
        System.out.println("Device is ready");
    }

    @Override
    public void onStop(IOEvent event) {
        // since this moment we are sure that the device is properly shut down
        System.out.println("Device has been stopped");
    }

    @Override
    public void onPinChange(IOEvent event) {
        // here we react to changes of pins' state
        Pin pin = event.getPin();
        System.out.println(
                String.format(
                    "Pin %d got a value of %d",
                    pin.getIndex(),
                    pin.getValue())
            );
    }

    @Override
    public void onMessageReceive(IOEvent event, String message) {
        // here we react to receiving a text message from the device
        System.out.println(message);
    }
});

To obtain more fine grained control we can subscribe to events of a particular pin.

Pin pin = device.getPin(2);
pin.addEventListener(new PinEventListener() {
    @Override
    public void onModeChange(IOEvent event) {
        System.out.println("Mode of the pin has been changed");
    }

    @Override
    public void onValueChange(IOEvent event) {
        System.out.println("Value of the pin has been changed");
    }
});

Changing the mode and value of a pin look like this:

pin.setMode(Pin.Mode.OUTPUT); // our listeners will get event about this change
pin.setValue(1); // and then about this change

You can get visual representation of device's pins using JPinboard Swing component.

JPinboard pinboard = new JPinboard(device);
JFrame frame = new JFrame("Pinboard Example");
frame.add(pinboard);
frame.pack();
frame.setVisible(true);

JPinboard allows setting the pin's mode by choosing one from a context menu of the pin. State of the output pin can be changed by double clicking on it.

An example of JPinboard usage can be found in org.firmata4j.Example class.

firmata4j sticks to Firmata protocol versions. The first available version of firmata4j is 2.3.1.

firmata4j-2.3.x will work well with Fimata v. 2.3.x. Actually it should work with Firmata v. 2.x.x but not necessarily support all of the protocol features. The first digits of versions must be equal because those stand for incompatible changes of the protocol.

Arduino IDE is shipped with an implementation of Firmata protocol. You can upload it as follows:

• Plug your Arduino to the computer
• Launch Arduino IDE
• Select File -> Examples -> Firmata -> StandardFirmata in IDE's menu
• Select your board in Tools -> Board
• Select the port in Tools -> Port (it is already selected if you have uploaded something to your Arduino)
• Click on Upload button

Arduino IDE may contain an outdated version of Firmata. You can update it using the guide on this page.

Currently firmata4j does not support working with I2C installations. I have no idea how to implement that because I haven't dealt with it in my applications. If you need this functionality and got an idea how that should be done, please, share it.

Contributions are welcome. If you discover a bug or would like to propose a new feature, please, open a new issue.

If you have an improvement to share, please, do the following:

1. Fork this repository
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Adds some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create new Pull Request

firmata4j is distributed under the terms of the MIT License. See the LICENSE file.