Projects / leJOS NXJ


leJOS is a Java-based replacement firmware (OS) for LEGO Mindstorms programmable bricks, including RCX and NXT. It supports threads, exceptions, synchronization, floating point arithmetic, strings, and so on, but there is no garbage collection yet. It is also designed to be portable to other small devices.

Operating Systems

Recent releases

  •  24 May 2009 16:17

    Release Notes: iCommand is no longer needed. PC control is now included in pccomm.jar and the lejos.nxt.remote package. RS485 support in lejos.nxt.comm. Support for RFID, RCX Rotation Sensor, and EOPD. Much more extensive support for Java 1.6 classes (including ArrayList). Support for Generics, Enum classes, and foreach loops. A fully working lejos.subsumption package. An NXJControl utility for quick control of motors and sensors. Wider support in the lejos.navigation packages. javax.microedition.location for Bluetooth GPS.

    •  05 Sep 2007 11:46

      Release Notes: This version includes a full suite of graphical widgets in the java.microedition.lcdui package, a multi-level menu system, wireless NXT to NXT communications using Bluetooth, primitive wav file sound support, and many more smaller enhancements.

      •  18 Jul 2007 16:32

        Release Notes: leJOS NXJ is a full replacement firmware JVM that allows you to run Java programs on the LEGO Mindstorms NXT brick. leJOS NXJ works with Windows, Linux, and Mac OS X. Version 0.3 includes a flash file system with implementations of, FileInputStream, and FileOutputStream, a menu system, Java streams over Bluetooth and USB, support for LCP (LEGO Communication Protocol) including file commands, a file explorer that runs on your PC, and much more.

        •  19 Dec 2002 03:38

          Release Notes: There are plenty of new features in this release, including a Vision API for Lego Vision Command, 100% Java versions of the lejos tools, USB support for Linux, exhanced USB Mac OS X support (including josx.rcxcomm), a new remote control package, and more.

          •  22 Jul 2002 15:49

            Release Notes: New features include more available memory without motor twitching, USB Mac OS X support, faster Math functions, and a vastly improved communications package. Now you can communicate with multiple RCXs, use a variety of protocols (including LNP), and even serve Web pages directly from your RCX.


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