RemoteBrick – The First Java API for LEGO® Inventor Hub (51515)

Control your LEGO® Inventor Hubs (51515) from Java — like the official LEGO app, but 100× more powerful.
No LEGO software. No Python. No limits. With Official Firmware on the HUB

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What is RemoteBrick?

RemoteBrick is a native, high-performance Java API for the LEGO® Education Inventor Hub (51515) used in SPIKE™ Prime and Inventor kits.

It communicates directly via Bluetooth Classic (SPP) — giving you full control of every feature the hub offers.

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Why RemoteBrick?

Feature	RemoteBrick	LEGO App	Pybricks
Language	Java 21+	Scratch/Python	MicroPython
Real-time Events	Full	Limited	Full
Thread-safe API	Yes	No	Yes
No Installation	Yes	No	No
100% LEGO App Parity	Yes	Yes	Yes
Windows Plug & Use	Yes	Yes	No
Multi Hub Support	Yes	No	No

RemoteBrick = LEGO App Features + Java + Easy Setup

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Features (100% LEGO App Coverage)

Category	Supported	Examples
Display	Full	Text, Images, Animations, Pixels, Rotation
Motors	Full	Speed, Power, Tank Drive, Degrees, Ramp
Sensors	Full	Color, Distance, Force, Gyro, Tilt
Sound	Full	Beeps, Notes, Duration, Volume
Buttons	Full	Press/Release, Duration
Hub State	Full	Tilt, Knock, Battery, Runtime
Broadcasts	Full	Send & receive messages
Async Commands	Full	Non-blocking .sendAsync()

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Plug & Use on Windows

No installation. No drivers. No LEGO app.

Requirements

• Windows 8+ / 10 / 11 (64-bit)
• Java 21 or higher (java --version)
• Bluetooth enabled Built-in or adapter
• LEGO Inventor Hub (51515) with Original Firmware

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Quick Start

Import via Maven Central / Gradle

<dependency>
    <groupId>de.juniorjacki</groupId>
    <artifactId>RemoteBrick</artifactId>
    <version>1.5.2</version>
</dependency>

implementation("de.juniorjacki:RemoteBrick:1.5.2")

or

Just download the latest release JAR from GitHub and add it to your project.

1. Download the Latest Release

Go to: Releases

Download: RemoteBrick-#.#.#.jar

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2. Add to Your Project

IntelliJ IDEA / Eclipse / VS Code

1. Create a new Java project (java --version ≥ 21)
2. Copy RemoteBrick-1.0.0.jar into your project folder (e.g., lib/)
3. Add as external library:
   • IntelliJ: File → Project Structure → Libraries → + → Java → select JAR
   • VS Code: Add to lib/, ensure java.project.referencedLibraries includes it

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3. Pair Your Hub

1. Turn on the hub
2. Open Windows Bluetooth Settings
3. Find LEGO Hub → Pair
4. Copy the MAC address → e.g., AA:BB:CC:DD:EE:FF

4.

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Code Examples

Connect to the Hub

import de.juniorjacki.remotebrick.Hub;

public class MyRobot {
    public static void main(String[] args) {
        // Replace with your hub's MAC address
        Hub hub = Hub.connect("AA:BB:CC:DD:EE:FF");
        //Hub hub2 = Hub.connect("AB:BC:CD:DE:EF:FG");
        //Hub hub3 = Hub.connect("AC:BD:CE:DF:EG:FH");
        
        if (hub == null) {
            System.out.println("Failed to connect!");
            return;
        }

        System.out.println("Connected! Battery: " + hub.getBatteryPercentage() + "%");
    }
}

Display Text & Animation

import de.juniorjacki.remotebrick.Hub;
import de.juniorjacki.remotebrick.types.*;

public class DisplayDemo {
    public static void main(String[] args) {
        Hub hub = Hub.connect("AA:BB:CC:DD:EE:FF");
        if (hub == null) return;

        // Scrolling text
        hub.getControl().display().text("HELLO WORLD").send();

        // Heartbeat animation (looping)
        hub.getControl().display()
           .animation(Animation.HEARTBEAT, false, 400, 100, true)
           .send();

        // Show smiley for 2 seconds
        hub.getControl().display()
           .image(Image.SMILEY, 2000)
           .send();
    }
}

Motor Control (Tank Drive)

import de.juniorjacki.remotebrick.Hub;
import de.juniorjacki.remotebrick.devices.Motor;
import de.juniorjacki.remotebrick.types.*;

public class MotorDemo {
    public static void main(String[] args) {
        Hub hub = Hub.connect("AA:BB:CC:DD:EE:FF");
        if (hub == null) return;

        Motor left  = (Motor) hub.getDevice(Port.A);
        Motor right = (Motor) hub.getDevice(Port.B);

        if (left != null && right != null) {
            // Forward for 3 seconds
            hub.getControl().move()
                    .startSpeeds(left, right, 70, 70, 100)
                    .send();

            try { Thread.sleep(3000); } catch (Exception e) {}

            // Stop with brake
            hub.getControl().move()
               .stop(left, right, StopType.BRAKE)
               .send();
        }
    }
}

React to Hub Events

import de.juniorjacki.remotebrick.Hub;

public class EventsDemo {
    public static void main(String[] args) {
        Hub hub = Hub.connect("AA:BB:CC:DD:EE:FF");
        if (hub == null) return;

        hub.getListenerService().addListener(new Hub.Listener.HubEventListener() {
            @Override
            public void newDeviceConnected(ConnectedDevice device) {
                System.out.println("New Device Connected Port " + device.getPort() + " Type:" + device.getType());
            }

            @Override
            public void deviceDisconnected(ConnectedDevice device) {
                System.out.println("Device Disconnected Port " + device.getPort() + " Type:" + device.getType());
            }

            @Override
            public void hubWasKnocked() {
                System.out.println("KNOCK! Hub was tapped!");
            }

            @Override
            public void hubChangedState(HubState newState) {
                System.out.println("New Hubstate " + newState.name());
            }

            @Override
            public void hubButtonPressed(HubButton button) {
                System.out.println("Button " + button.name() +" pressed");
            }

            @Override
            public void hubButtonReleased(HubButton button, long duration) {
                System.out.println("Button " + button.name() +" held: " + duration + "ms");
            }

            @Override
            public void receivedBroadcastMessage(long hash, String message) {
                System.out.println("Received broadcast message: " + message);
            }
        });

        System.out.println("Listening... Press buttons or knock the hub.");
    }
}

Troubleshooting

Issue	Solution
Hub.connect() returns null	Check MAC address, pairing, Bluetooth on
DLL error	Run on Windows only
Motors not moving	Check port, motor type
JAR not found	Add RemoteBrick-*.jar to classpath

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License

CC BY-NC 4.0 License
Copyright (c) 2025 JuniorJacki