What is leJOS?

leJOS (pronounced like the Spanish word "lejos" for "far") is a tiny Java-based operating system that has been ported to the following platforms: leJOS was originally forked out of the TinyVM project.
It contains a VM for Java bytecodes and additional software to load and run Java programs.

These are some of the features offered:

Preliminaries

Installation and Set Up

Please download the leJOS documentation from the same location you downloaded this distribution.
  1. Set your environment variable LEJOS_HOME to the directory you installed this distribution into
  2. Add leJOS's bin directory to your PATH
  3. On Linux, depending on the privilege settings you might need to adjust the execution permissions in the bin folder
On Linux, you will have to build the distribution first. To do so, switch to the build folder and run ant. Note that depending on the privilege settings you might need to adjust the the execution permissions in the release folder.

Using lejos on the NXT

Your NXT must be plugged into the USB, switched on, and in firmware update mode to run lejosdl.

To go into firmware update mode press the reset button (at the back of the NXT , upper left corner) for more than 4 seconds. Your NXT will audibly tick when it is firmware update mode, but is not running a lejos program.

To switch your NXT on, just press the orange button. It will start to audibly tick.

When you use lejosdl your program will download and run. You can stop a program by pressing the ENTER and ESCAPE (orange and grey square) buttons together. This powers down the NXT immediately. Press the ENTER (orange) button to wake it up again.

You can also power down the NXT with ENTER + ESCAPE, after an Exception occurs.

Known limitations

Due to size constraints, some Java language features have been omitted. Others just haven't been implemented yet. Known limitations are:

Known Bugs

Documentation

Please download the leJOS documentation from the same location you downloaded this distribution from. The documentation contains the API docs.

License

We are continuing to release under the Mozilla Public License (see the LICENSE file). The runjava utility using David Anderson's libnxt which is release under a GPL v2 license (see COPYING in the libnxt directory).

Questions and Problems

Please direct feedback to the lejos-discussion mailing list mailto:lejos-discussion@lists.sourceforge.net.
To subscribe, see http://lists.sourceforge.net/lists/listinfo/lejos-discussion.

Feel free to take a look at the Lejos website or its project page.