Re: Wii whiteboard
Hi Petter,
On Thu, Dec 03, 2009 at 10:28:34PM +0100, Petter Reinholdtsen wrote:
> [Klaus Knopper] wrote:
> > You just need:
> >
> > 1. A wii-controller (just the controller, not the wii)
>
> Check. :)
The original wii controller is much more sensitive to infrared than the
cheaper rebuilds, btw.. I already checked on that.
> > 2. A infrared led pen, you can get these from various resources (check
> > for "wiimote infrared pen", "the groove"), or build one by yourself
> > if you are not afraid of a soldering iron,
>
> Used my stereo IR remote, pressing the volume button, for testing.
> Worked great. :)
The stereo or tv remote control sends pulsed signals, which is not very
precise to the point, I guess. You can use a candle, too.
I have successfully built IR pens from cheap LED (torch) mini pens
available in most electronic stores for less than 3 Euros. You replace
one of 3 batteries by a metal disk of the same size to reduce the
voltage, and replace the LED by a TSAL 6400 IR LED, plus a resistor in
line, which needs to be about 22 Ohm for 3 Volt. If you just use one
battery, you can leave the resistor, but you don't get the maximum
brightness.
The best commercial pen I found so far is "The Groove", which you can
buy at http://www.wiiteachers.com/ for about 30 dollars. It looks
somewhat clumsy compared with a selfbuilt mini pen, but the single AAA
battery lasts longer than two cell micro batteries, and the switch which
allows you to switch on the LED by pressing it against the board, is
really practical.
> I installed and used wmgui to debug the connection to the Wiimote, and
> used it to see the output from the IR camera. I suspect it will make
> it easier to adjust the view of the wiimote when trying to make it see
> the entire screen. :)
Hint: If you remove the rubber surrounding of the wii remote, you get a
better angle range to match the board width.
> Very cool. Will have to get a real IR pen now. Anyone know where I
> can buy one here in Oslo?
Can't answer that, but I would recommend just ordering one to be send by
mail.
> Anyone know how the different colors are detected with the IR pens
> available from <URL:http://www.wiiteachers.com/>. Can gtkwhiteboard
> handle multiple colors?
I don't think so. Since the frequency range of the IR pen is fixed, the
only way to distinguish "colors" is probably seding not a constant
signal, but a pulsed signal. gtkwhiteboard can probably not handle this
yet.
But you may be able to assign keys to the outer edges of your board, so
you could just define a hotkey for changing colors in gimp or similar
applications, and click the corresponding area outside of the board in
order to activate it.
In xournal, there are easy to reach buttons for switching colors with
just one pen.
> Is there some way to get visible feedback for the calibration? When
> using a projector on the whiteboard screen, it would be useful to have
> indicators on the corner positions to know where to put the IR pen.
There are thumb rules about where the wiimote is located best, for
example, "use a distance which is about twice the width of the board",
so the wiimote will see the entire board.
Regards
-Klaus
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