Wiimote Whiteboard

[Matt Grommes]

One day at work, a coworker passed around a link to a video by a guy named Johnny Lee about a new use for the Wii remote (or wiimote). He used it to to see the light from an infrared light pen and used the pen to literally draw on the screen. This, of course, is awesome. We all decided we had to figure out how to build this system. I offered to build the light pens and another coworker offered up his Wiimote.

First, the light pens are pretty easy to build. Since this was literally going to be the first electronics project I'd ever done, I also used an Instructable on LEDs for Beginners to figure it out first. There's a bunch of tutorials if you search on Google. Here's the completed pen.

The hardest part is getting all the parts inside the pen but I liked the idea of using a real pen and not just a bunch of electronics. I got the IR LED at Radio Shack, the pens at Office Max, and a AA battery holder at Electronic Parts Co. (on Rhode Island a bit north of Menaul, an essential place for any electronics hacker but they're only open 8-5 M-F - hence the visit to Radio Snack).

Once I got the pens built, I just followed the various available instructions for putting the BlueSoleil bluetooth software on my laptop and connecting the Wiimote to the laptop. Once you do that, Johnny Lee has the software to let you use the light pen as a mouse and move the cursor around. Look in the Videos section above for my first whiteboard experiment using Paint to draw with the light pen.

The most fun thing I've done so far is when I hooked everything up at work on a big screen in one of our conference rooms and we played with Crayon Physics. CP is a fun little game where you draw shapes to try to make a ball move and touch a star. It lends itself perfectly to the light pen and we all had tons of fun playing with it one lunch. Highly recommended if you're going to built a Wiimote whiteboard. I gave the wiimote back to my friend so his son could use it for its intended purpose so I haven't played with things any more but we have lots of ideas for more things we can do so I'll have more reports in the future.

This was a fun and easy project which I would recommend if you have access to a Wiimote.

If you have comments or questions, reply to this discussion. I'd also love to see what other people have seen regarding Wiimote projects.

[Aaron]

I have not followed all the software, but I have written similar software for custom applications.
He may have a lead on some cheap/free software to do the job far more effectively that I ever could starting from scratch.

I wonder how hard it would be to set this up with a standard, cheap, security camera.
I have one for $70 with motion detection, that will even FTP frames to a server!
Would it even work as well?
Perhaps the wii has an embedded app just for tracking an IR source.
It will take a LOT of computational resources to track IR video frames in real-time!
That... or... a lot of work with things like gating algorithms.
But my cheap security camera does not do gating. Computer vision cameras that do have gating
functions are more like $1000 and up.

Trouble I would have with a camera is discriminating the weak IR source, from other sources, like
the projection light, which are also likely to have presence in the IR.
I could be wrong. Perhaps if you are at a long enough wavelength, there is not much
IR signature from projectors, LCD's, etc.

There is certainly a world of possibilities opened up by these cheap, IP security cameras, too.

[Matt Grommes]

The Wiimote has builtin tracking for 4 IR points and has a resolution of 1024x768, for only $40. If you look at the comments on Johnny Lee's site, people there say the Wiimote ends up being the cheapest alternative.

I think the Wiimote has enough smarts to know that the moving IR source is the important one, not a stationary lamp. I might be wrong about that but I haven't had any issues with sunny windows or lamps.

[Aaron]

Pretty slick. I read up. yea. it has a camera AND a tracker.
I have never seen a Wii. Is this a standard part of the Wii?
Is this how it works? ... Tracking IR lamps? Or is the wiimote an add-on.

Either way... yea.... the possibilities of a little $40 IR integrated tracker are great!

[Aaron]

sorry to double reply... I started thinking.
This speaks bluetooth... is that right?

Either way... start thinking about what you could do if you mount that as a sensor on a robot.
Even just simple things like try to drive the IR spot to the center, and attach to servos to follow the spot.
Yes we can do this with a simple camera, but the Wii does not bog down our computer with frames to
process, just a spot location. I haven't messed with things like ARM's yet... (like in cell phones)...
but I bet there would be cheap microprocessors that could speak bluetooth.

[Aaron]

I guess I'm not feeling very original today... but we will play with this.
I got the OK to buy a Wiimote for work, $40 at amazon, free shipping.
(I saw them for $30, but am always weary of lowest price vendors)

We'll try it on the BlueTooth equipped laptop. If it is useful, we'll get a Bluetooth RX for the conference room computer.
Perhaps mounting the wiimote on the ceiling above the screen will work.

Do you need to hit any buttons on the Wiimote to get the application running?
We might want to do a semi-permanent mount, and just wire the wiimote to a 3v supply.
Changing batteries might be burdensome.

Is the wiimote really narrowband, near-ir? would it work from a red LED?
Even if we build an IR LED pen, we will wantsome visible output just to monitor battery health.

[Matt Grommes]

You do need to hit the connection buttons on the Wiimote for it to sync up to the bluetooth on the computer. I forget if the Wiimote turns itself off after a time or not, I've only used it for 45-60 minutes at a stretch. The only place I've ever mounted the Wiimote is off to the side of the screen but mounting it above the screen (and back a little so can get both the X and Y axis) pointing down might be a good idea so the user doesn't get in the way.

I think when I was first playing around with it, I tried a couple of different colors of LED and didn't have much success. I'm not sure if the brightness of the LED might make a difference, maybe a bright enough red LED would work. I toyed with putting an extra color LED on my pen to monitor battery of the pen but the AAA battery I used has lasted a long time and the application Johnny Lee provides gives you battery status direct from the Wiimote so I just use that.

Once you get it going, this might be a great project for talking about at a meeting, if you're interested in doing a short talk about it. I'm sure you could get some good ideas from other members.

[Aaron]

I have implemented this.

I got the Cirago BTA-3210 USB-Bluetooth adapter.
It comes with the Toshiba Bluetooth stack, which supports the Nintendo Wii HID interface without change.
I did NOT need to go get BlueSoleil.

This is a really nice micro-sized adapter for laptops. Costs a bit more ($40 vs. the usual $20), but
its worth it for the Toshiba stack, and the ability to leave it in your laptop when stored.
It is very, very small. Sticks out about 4mm.

I got an IR-LED from RadioShack. This is a bit of a unique device.
It has a 1.2v drop, at nominal 100mA current. This means that we can
run it off of a typical alkaline cell with about a 2 ohm ballast.
It will shut down when the cell is about half-deal at about 1.3v, but that should take some time.
I would not hesitate to run it off of a 1.2v NiCd or MiMH. It draws about 150mA at 1.3v,
which will (probobally) not burn it out. A very fresh NiCd will be 1.5v, but a small one
will rapidly drop to 1.3v at 150mA, so I bet you would be safe without a ballast on those.

However, since most visible LED's drop about 2v, I could not put a visible indicator on my single cell pen.

I just placed an order to Electric Goldmine for their grab-bag of IR led's. 20 of them, I think... and
some microswitches. I plan to make one on a pen next.
For now I'll just tape a battery holder to the pen. Eventually, I'll see if I can get
a 2-3 cell watch battery holder, and run the IR-LED along with a small visible indicator,
and perhaps a spare Laser pointer.

I think the best thing to do here, cost wise, is to find a pen-light, or laser pointer,
and replace some parts. I'm keeping my eye open.

The Wiimote is really bas-ass! An IR camera with 4 blob trackers, AND 3-axis accelerometers
for $40 (through the Amazon shop I used). The possibilities are AMAZING.
This little sensor suite could rock the universe!

[Aaron]

I just got an LED key-fob last night (used).
Two of those wide-flat Lithium 3v batteries... producing... 3v!
(I'd guess that if they were fresh, it would be more than 3v each.)

The LED was running about 20ma when on at 3v.
I double checked the battery internal resistance... looked like about 45 ohm.
The 20ma was from my power supply, which may not be reliable at
that low current. 3v from the batteries seemed to be 65mA from the resistor.

These little lithium batteries are odd beasts. Voltage and current dropped rapidly.
They seem to have some sort of temporary drain that happens quick. OC voltage drops.
About .1v/sec under 65mA (ish) load.

I don't have all that much practical experience, even less with those Li watch cells.
I'll hook up an IR camera next time so I can judge LED "brightness" when selecting ballast.
I think most IR LED's will run at significantly less than 3v, so I'll need an extra ballast
resistor to use the two watch cells in the key-fob.

Do you think I might be OK without ballast, say on a 2v LED... just using the Li batteries
voltage drop character to prevent burn-out?
I think It might be like a ceramic heater. If the Li battery voltage drops fast,
the LED won't stay over-current long enough to burn-out. Extra-bright, over-current
condition may not harm it for .1 sec at a time---- mouse clicks