Chapter Four : WiiMote extension (software)
OK so by now you have a working laser harp that triggers notes when your hand enters the beams.
Not too shabby!
(I fully expect Jean Michel-Jarre to raise the bar in his next concert tour, now that the cat is out of the bag regarding the traditional laser harp – not sure what he’ll come up with but I hope it’s as impressive today as the laser harp was in 1986)
The problem with the standard laser harp is that it’s not very expressive – we need more control over the sound as we break the beams. Soon after I finished the first release of the harp I was introduced to the work of Johnny Chung Lee over at the WiiMote Project site. I had no idea that the WiiMote had a hardware blob tracking camera built in to the front.
So I followed some of the examples and managed to get a WiiMote + BlueTooth + Software solution running that allowed control of MIDI parameters by sliding your hand up and down in the beam.
For this you will need:
- A WiiMote
- A WiiMote dissasembling TriWing screwdriver (warranty now void)
- A BlueTooth adapter and stack (I use this one)
- A .Net framework
- My modified Wiimote software for Windows << Click to Download
- A Copy of MidiOX and MidiYoke
- A Software Synth (I use this)
- A Working laser harp
- A flask of weak lemon drink (optional)
First thing to do is open up the WiiMote and remove the black plastic filter over the front of the camera (this is a sensor made by PixArt that can track up to 4 bright “blobs” on screen). Replace the cover and attach a notch filter to the front if you have one – alternatively green transparent plastic helps.
Attach the WiiMote to the harp sensor so that it has the same field of view.
Next step is to install MidiOX and MidiYoke. We are going to create a virtual MIDI cable and merge the output of the Laser Harp with control messages from the modified WiiMote Software.
Set this up so that MIDI Yoke-1 and the input from your laser harp are routed to Midi-Yoke-2. Then use Midi-Yoke-2 as an input to your sampler, synthesizer (or use one of your hardware outputs for an external device)
Install BlueSoleil if you have it (The built in Microsoft Blue Tooth does not seem to connect to a Wiimote correctly). Search for the WiiMote and then right-click on the icon for it and select “Connect”. If you have done it right then the device indicator will turn green.
Run my software, if you connected the WiiMote OK then the software will run, if not you will get an error “Wiimote not in HID list”.
Fill in the MIDI controller ID you want to control, and click “Run”.
(On the impOSCar I’m using the frequency cutoff control which is ID 74 – although the image shows controller 77).
If you have everything running and connected correctly, you can start up the harp and it should now behave like this:
Drink your weak lemon drink…. NOW!
In the next part I’ll be looking at removing the pixart sensor and creating a completely hardware solution…