Chapter Five : WiiMote tracking (Hardware solution)



New for 2011 – check out the MIDI Camera
– gesture control with no Bluetooth, or even a PC!


Last year I tried to find out if it were possible to connect a PixArt blob tracking camera directly to the Arduino. I knew they both spoke I2C and in theory it should be possible. I posted on the Wiimote project forum to see what was out there.

(I knew that if I gave it long enough, someone else would crack the code.)

Now that they have, it’s time to try to create a hardware only tracking Laser Harp. There are two sources of info out there – one from Johnny Lee himself, and the other from Kako – here is the Babel Fish translation of the original Japanese site.

This is new ground for me, and so I will be using a breadboard first, and soldering things down later.


First off,  we need to get the sensor out of the WiiMote, you can either desolder it, or just cut the board (bye bye WiiMote).

Try to clear the two outer posts first before desoldering the 8 pins

Try to clear the two outer posts first before desoldering the 8 pins

Next we need to provide a 25Mhz clock signal, and 3.3V regulator to power the camera.

The Arduino does have a 3.3v line, but I think you are better off with a separate regulator.

The seeing Arduino type thing...

The seeing Arduino type thing...

Connecting the Pixart sensor

Connecting the Pixart sensor

Pinout and connections of an Atmel 168

Pinout and connections of an Atmel 168

Now the *really* tricky bit. We need to add an LTC4301L  5v/3.3v I2C buffer chip. These only come in MSOP form factor and are just like surface mount – very difficult to solder.  Here is everything you need to know about soldering surface mount components.

Adapters are available to convert the MSOP to more manageable DIP form factor here.

LTC4301 - yes it really is that small

LTC4301 - yes it really is that small

I can just about solder these things now, but it took me a couple of goes to get “the knack”.  I ordered 3 of the chips – just in case.

Downloading and running Kako’s sketch should get the whole thing running, like this:

(With a quick appearance by my daughter…)

I just finished the first pass of the C++ object library for accessing the WiiMote/Pixart sensor from an Arduino. A simple example included with the library.

Download Library

I then mounted this detector along with two standard TAOS detectors in a neat metal box I found.

New Detector - note the MIDI port

New Detector - note the MIDI port

Top view

Top view

try to avoid using tape... :-)

try to avoid using tape... :-)

The second Arduino will relay the MIDI data coming from the harp body, and mix in the MIDI controller information based on the readings taken from the Pixart sensor. This is why the MIDI output port has been moved to the detector case.

I have some simple serial relay software running for the MIDI data, I just need to get the ‘merge’ function going.

But for now, it’s time for a break…

{ 2 comments… read them below or add one }

Oleg Savchenko December 8, 2010 at 6:24 pm

Hi, Steve!
I’m very interested in this device – “Wii-Sensor-Extension for Arduino” or “Arduino-WiiSensor-Shield”.
Good Job! Waiting for the next results!
Whether I can receive the extended diagram (plan, circuit, list of components etc.)?
You are planing to finish this project before New Year or after it?
P.S. your daughter are so pretty ;-)) She helps you with your work?

kareem dawood May 13, 2012 at 5:33 pm

Hi,
I am going to implement this device and i have a question if you don’t mind…
how can i test each part to find where is the fault ……and especially how can i test the I2c Chip ???
thanks in advance

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