Wednesday, October 22, 2008

Educational Use of the Wii remote

The Nintendo Wii videogame has a handheld controller, the Wii Remote. The Wii Remote has the ability to sense acceleration along three axes through the use of an ADXL330 accelerometer. It also contains a 1024x768 infrared camera with built-in hardware blob tracking of up to 4 points at 100Hz. The Wii Remote communicates wirelessly with the console via short-range Bluetooth radio.

Johnny Chung Lee has Demonstrated how the infrared camera can be used for third party applications including an interactive whiteboard at http://www.cs.cmu.edu/~johnny/projects/wii/ Another third party project, GlovePIE by Carl Kenner allows the Wii Remote to be used on a personal computer to emulate a keyboard, mouse or joystick. http://carl.kenner.googlepages.com/glovepie


Hardware
A IR LED light source is required. The LED chosen is the CAT. NO. ZD1945 from Jaycar Electronics

It has the following specifications:
Forward Current (If): 50mA max - Peak forward current (Ip): 1.2A- Forward Voltage (VF): 1.2V @ 20mA - Reverse Voltage (VR): 5V max- Power Dissipation (Pd): 100mW max - Viewing Angle: 30°- Peak Spectral Wavelength(IR): 940nm @ 20mA * Spectral Bandwidth (DI): 50nm@20mA- Material: GaAs

It was chosen to run it conservatively at 14 mA with a 1.5V battery and 22 ohm series resistor.
(1.5V -1.2V)/22 = 14mA

The longer LED lead connects to the battery + , the resistor is in series.


The IR source can be easily tested because webcams and digital cameras can receive the IR spectrum as the following photo shows:


Low-Cost Multi-point Interactive Whiteboard Software
Johnny recommends BlueSoleil, a third-party driver that implements the full Bluetooth stack for various Windows operating systems. You can download a trial version that has a 5MB transfer limit at http://www.wiili.org/index.php/BlueSoleil

This driver was not required (running a Dell Inspiron 1520 with Vista), the Windows driver accessed through Control Panel was sufficient. Open control panel and click on the Bluetooth icon


While pressing the A&B buttons on the Wii Remote, click on add.


Select the Wiimote when it appears and select no passkey.


Download the whiteboard software from http://www.cs.cmu.edu/~johnny/projects/wii/

Run the whiteboard executable WiimoteWhiteboard v0.2.exe , if you have alrerady established Bluetooth communucation with the Wii it should load:


Clicking on Calibrate Location brings up the 4 calibrate points, flash the IR LED at the four calibrate points.

Tracking Your Fingers with the Wiimote
http://www.cs.cmu.edu/~johnny/projects/wii/WiiMultipointGrid.zip should run without the directx SDK but gave the following error “Directx SDK sample has stopped working.”

GlovePIE
Blue Soleil was not required. Just download the GlovePIE zip from and run GlovePIE.exe
You can setup the Bluetooth from within GlovePie by choosing the Control Panel-Settings > Bluetooth menu in GlovePIE. You should then select Bluetooth Fix from the Troubleshooter menu.


press add and hold down the 1+2 buttons on the Wiimote, tell your Bluetooth program to search for devices,


I chose no passkey.
Generate an appropriate script, either by typing into the left script tab or by selecting options from the GUI tab.

For example, the following script gives control over a dummy mouse pointer and can easily be generated using GUI tab options.
Cursor0.x = MapRange(Wiimote1.Roll, -90 degrees,90 degrees, 0,1)
Cursor0.y = MapRange(Wiimote1.Pitch, -90 degrees,90 degrees, 0,1)

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