The leJOS Tutorial

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Trail: Getting Started

# Lesson: Solving Common Problems

If you have troubles compiling or running leJOS programs, this section might prove useful for you. If you don't find help here, consult the leJOS FAQ pages or visit the leJOS discussion forum.

## Downloading problems

The firmware or a program can not be downloaded to the RCX
Make sure

- your RCX is turned on
- your RCX's IR port (the dark panel on the front) is facing towards the IR tower
- you have set all your environment variables correctly.
  See Your first brick of leJOS for details.
- there is not an abundance of ambient light. The communication between the IR tower and the RCX is based on infrared light and thus rather picky in respect to too much luminance around it.

## Compiler problems

The Compiler doesn't find lejosjc
Make sure you have set all your environment variables correctly.
See Your first brick of leJOS for details.

The Compiler doesn't find the leJOS classes
Make sure you have set your `CLASSPATH` environment variable accordingly.
See Your first brick of leJOS for details.

## Execution problems

The Compiler doesn't find lejosjdl
Make sure you have set all your environment variables correctly.
See Your first brick of leJOS for details. The RCX behaves in an unpredictable way
Besides any programming bugs, there always is the possibility of the RCX's energy source, i.e. the batteries, are drained. When switching on the RCX, the LCD shows the actual charge; for rechargable batteries a value of 7.5 V is common, for non-rechargable ones it is 9 V.

To be continued..

The leJOS Tutorial

| Start of Tutorial > Start of Trail