LeJOS & Eclipse Installation Guide for Windows 2000 / XP

An easy way to get started with Java for Lego Mindstorms

Introduction

Eclipse is an open source Integrated Development Environment for JAVA that works perfectly together with LeJOS (Lego Java Operating System), which enables programmers to control Lego Mindstorms with Java. This is a very powerful combination that increases the ease of programming the RCX. Here is a quick guide that explains you how to set it up:

Step 1: Install Java 2 SDK

Download version 1.4.* of Java 2 SDK at http://java.sun.com
Run the installation file

Step 2: Install LeJOS and Eclipse

Download the latest version of LeJOS at http://lejos.sourceforge.net and extract the .zip file to C:\ so that you create C:\Lejos\...
Download version 2.*.* (3.* won't work) of Eclipse at http://www.eclipse.org and extract the .zip file to C:\ so that you create C:\Eclipse
Download the LeJOS plugin for Eclipse here and extract the .zip file to C:\Eclipse\plugins

Step 3: Setup Eclipse

Open Eclipse with C:\Eclipse\eclipse.exe
Click Window -> Preferences
Go to leJOS pane
Fill in the leJOS installation directory, which is in this case C:\Lejos
Choose com1 for RCX communication port
Choose slow for data transfer rate. If you choose fast, the chance is very high that a data transfers fail since the signal is very sensitive for external light
Confirm your settings by clicking the OK button

Step 4: Start a project

Click File -> New -> Project…
Select “ LeJOS project” and click Next . This wizard will let you enter some details for the project. Usually it's enough to enter your project name and click Finish to confirm
Open the Java perspective by clicking Window -> Open Perspective -> Java
To start coding add a new class to the project by clicking File -> New -> Class
Your code is compiled at your cursor and eclipse will indicate errors at your cursor

Step 5: Patch the RCX firmware for LeJOS

Make sure that the IR tower is connected to the computer and the RCX is in range of the tower and switched on.
Click LeJOS -> Firmware Dowload

Step 6: Upload your code to the RCX

Open the class of your project that contains the main method
Click LeJOS -> Bytecode Download