programming for lego mindstorms using eclipse to take you back to your childhood!

Programming forLego® Mindstorms™using Eclipseto take you back to your childhood!

Benjamin CabéOct 28th, 2009

Agenda

The Mindstorms NXT brick

The LeJOS VM

Eclipse + Mindstorms = FUN!• Implementing an RSE connector• Data visualization inside an Eclipse editor• State machines modeling and code generation

©2009 Sierra Wireless inc. – Made available under EPL v1.0

The NXT brick

32-bit ARM7 processor @48MHz

256kB of Flash

64kB of RAM

100x64 pixel LCD display

USB 2.0

Bluetooth

Open Source firmware!©2009 Sierra Wireless inc. – Made available under EPL v1.0

4 input ports


3 output ports (motors)


LeJOS NXJ VM

A tiny (10kb) but still cool Java VM• Threads / Synchronization• Exceptions• Most of the java.lang, java.util and java.io

classes• Generics, enums, « for each » loops• A “robotics”, event-based, API• Open Source!

Limitations• No Garbage Collector• No switch()


LeJOS NXJ Eclipse plug-in

Useful to upload firmware and/or programs to the brick

Not much integrated in the IDE…

… how about leveraging DSDP/TM?!


TM/RSE hacking

LeJOS NXJ comes with APIs to :• List/get/send files• Execute programs• Get sensor states

… it should be possible to define an RSE connector and a file subsystem…!


Brief RSE introduction

A framework at Eclipse to connect to remote systems and provide:• remote file systems through SSH, FTP, a dedicated

agent, or whatever• remote shell access• remote process monitoring• remote debugging (gdb)

It comes with generic, reusable, UI


TM/RSE hacking (2)

In a couple of hours:• A new 'LeJOS' system is available• An RSE file 'subsystem' allows to:

–Browse the brick's filesystem–Remotely execute programs

• Another subystem could bewritten to retrieve sensors values

Nota: Communication with the brick can be done using either BT or USB


TM/RSE hacking (3)

Very straightforward 1..1 mapping between RSE and LEJOS APIs

Example: LejosRemoteFile implementation

public void launch() throws IOException {

LejosConnectorService connector = (LejosConnectorService) getParentRemoteFileSubSystem()

.getConnectorService();

connector.getComm().startProgram(_hostFile.getName());

}

RSE

LEJOS©2009 Sierra Wireless inc. – Made available under EPL v1.0

Let’s toy a cool sonar!

Follows a closed track

Scans the interior of the track with the ultrasonic sensor

Writes a binary output file into flash memory• The file will be retrieved using the RSE connector


Robot behavior


Robot Java program

public static void main(String[] args) {

tachoNav = new TachoNavigator(5.6f, 11.5f, Motor.A, Motor.B);

File fRadar = new File("result.radar");

FileOutputStream fosRadar = new FileOutputStream(fRadar);

tachoNav.goTo(0, TERRAIN_WIDTH, true);

while (tachoNav.isMoving()) {

int dist = ultrasonic.getDistance();

fosRadar.writeInt(dist);

}

}


Display captured data

In an Eclipse editor associated to .radar files• Parse binary files• Process signal • sin(α)… cos(α)… Remember?!

Since the ambient noise level is also recorded, we can display it in a similar manner http://www.sxc.hu/photo/1099687


http://www.sxc.hu/photo/1099687

17

State machines modeling

LeJOS comes with an event-based robotics API, remember?

Eclipse has a bunch of cool modeling/diagramming/code generation technologies

… how about mixing both?!


18

LeJOS Visual Development Toolkit

A state machine framework on top of LeJOS

A GMF editor

Xpand templates for code generation

An integration with the LeJOS Eclipse plugin• Auto-deployment of the binary• Communication between the brick and the IDE to

monitor the state machine


Questions?

Benjamin Cabé[email protected]

mailto:[email protected]

If you wanna play by yourself!

http://www.mindstorms.com

http://lejos.sourceforge.net

http://www.juanantonio.info/p_articles/archive/2008/leJOSStatemachineDevelopmentToolkit.pdf

http://www.eclipse.org/dsdp/tm/


http://lejos.sourceforge.net/








programming for lego mindstorms using eclipse to take you back to your childhood!

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