Coding for Kano Wand outside the app

This article is for those who receive a Kano Harry Potter Coding Wand, perhaps as a gift. You try the App that comes with it and then think “This is an interesting piece of hardware. What else can I do with it?”

Well I hope so. That is why I bought one as a gift - and I’m not the first to see its potential as a remote control device.

This is my record of what I discovered before it went on its way to a new owner.

What is this thing?

It can be a magic wand

or a neat little bluetooth device

Can I talk to it from my Linux computer?

I was using Ubuntu Bionic. Package names and filenames may differ on other systems or versions.

You will need a Bluetooth host adapter which supports Bluetooth Low Energy, some software which may not already be installed, and to grant some extra privileges to the hcitool program.

These instructions are from Stack Exchange

sudo aptitude install bluetooth bluez libcap2-bin
sudo setcap 'cap_net_raw,cap_net_admin+eip' `which hcitool`
hcitool -i hci0 lescan

If your device can’t do Bluetooth Low Energy, you may see Set scan parameters failed: Input/output error. If you have multiple Bluetooth host devices you can use a different one by name. hci0 is the default and hcitool dev should list what you have available. I didn’t do this and haven’t shown how to do it when using the other code below.

If it is working, you will see LE Scan .... Wake the wand and it should show itself like Kano-Wand-xx-yy-zz. OK, your hardware is working! Press ctrl-C to stop.

Can I talk to it from my MacOS X laptop?

Probably, if it’s not very old. I haven’t looked up the equivalent of hcitool lescan.

This MacBook A1278 works fine, and it’s probably the mid-2012 model.

Other tools that will be needed

We’re going to need some compilers. We will also need a distributed version control system called Git which will be useful for fetching other people’s software.

Under Ubuntu Linux, in addition to the Bluetooth-related tools above, they can be fetched with sudo aptitude install git build-essential . In older Ubuntu, the git package was known as git-core. build-essential brings in a commonly useful assortment of compilers and libraries.

On a Mac, the XCode tools can be installed from the Apple Store and Git is included. Exactly how this is done may differ between versions of MacOS, but Homebrew helped me to get it right.

Can I talk to the Wand in Javascript?

Yes! But the instructions are a little different between Mac and Linux, because the noble package which provides access to Bluetooth LE has a Mac-specific fork called noble-mac.

The kano-wand-nodejs project I used was started by megabytemb a year ago, and other people have extended or modified it. This is how it looks in Github’s “project fork” view.

On Mac, the default master branch of megabytemb’s project worked for me.

On Ubuntu Linux, the grpc branch of GageAmes’ version worked for me.

Either way, we need NodeJS to run the Javascript, which includes the Node Package Manager to fetch more code libraries.

• On MacOS I used Node 12.14.0 LTS installed via Homebrew .
• On Bionic it was 8.10.0~dfsg-2ubuntu0.4 .

Javascript on Ubuntu Bionic

We can install everything, fetch the project and run the example with a few lines.

sudo aptitude install npm nodejs libbluetooth-dev libudev-dev
sudo setcap cap_net_raw+eip $(eval readlink -f `which node`)
git clone -b grpc https://github.com/GageAmes/kano-wand-nodejs

Javascript on MacOS

To install NodeJS I start with Homebrew so I didn’t need any administrator privileges.

cd
git clone https://github.com/Homebrew/brew
cd brew/
xcode-select --install
bin/brew install node
cd
git clone https://github.com/megabytemb/kano-wand-nodejs

Javascript anywhere

Once NPM is working and the correct kano-wand-nodejs is downloaded, the process is the same.

cd kano-wand-nodejs/
npm install
node example.js

Enter the downloaded project directory. Tell npm to install everything listed in the package.json and package-lock.json files. Run the example!

It should wait until the Wand is woken up, then

foundWand
[ '[Kano-Wand-xx-yy-zz]', 'init' ]
[ '[Kano-Wand-xx-yy-zz]', 'Discovering services...' ]
[ '[Kano-Wand-xx-yy-zz]', 'Found' ]
[ '[Kano-Wand-xx-yy-zz]',
  'Discovering characteristics for service with UUID' ]
[ '[Kano-Wand-xx-yy-zz]',
  'Discovering characteristics for service with UUID' ]
[ '[Kano-Wand-xx-yy-zz]',
  'Discovering characteristics for service with UUID' ]
[ '[Kano-Wand-xx-yy-zz]', 'Found vibrate characteristic' ]
[ '[Kano-Wand-xx-yy-zz]', 'Found button characteristic' ]
[ '[Kano-Wand-xx-yy-zz]', 'Found keep alive characteristic' ]
[ '[Kano-Wand-xx-yy-zz]', 'Found position characteristic' ]
[ '[Kano-Wand-xx-yy-zz]', 'Found ResetChar characteristic' ]
[ '[Kano-Wand-xx-yy-zz]', 'Subscribe to motion characteristic' ]
[ '[Kano-Wand-xx-yy-zz]', 'Subscribe to button characteristic' ]
[ '[Kano-Wand-xx-yy-zz]', 'Reset position' ]
[ '[Kano-Wand-xx-yy-zz]', 'Wand ready!' ]

Now hold the button down and draw a spell

{ score: 0.9995614290237427,
  spell: 'Avis',
  positions: 
   [ [ 493.3333333333333, 158.10000000000002 ],
     [ 492.44444444444446, 158.7 ],
     [ 491.55555555555554, 159.3 ],
     [ 489.77777777777777, 157.8 ],
     [ 487.1111111111111, 151.8 ],
     [ 488.8888888888889, 136.5 ],
     [ 495.1111111111111, 118.80000000000001 ],
     [ 508.44444444444446, 105 ],
     [ 522.6666666666667, 99 ],
     [ 533.3333333333333, 110.69999999999999 ],
     [ 536, 129.3 ],
     [ 529.7777777777778, 149.39999999999998 ],
     [ 530.6666666666666, 148.2 ],
     [ 548.4444444444445, 132.89999999999998 ],
     [ 585.7777777777778, 106.79999999999995 ],
     [ 616, 94.5 ],
     [ 633.7777777777778, 105 ],
     [ 643.5555555555555, 124.5 ],
     [ 644.4444444444445, 141 ] ] }

(That’s the only spell I can get right reliably.)

Can I talk to the Wand in Python?

Maybe, but on Ubuntu Bionic I ran into problems and found easier success in Javascript. I will try again if I have time, but for now this section is incomplete.

From the Adafruit blog I continued to Instructables. There I partly followed the instructions and partly followed my nose.

sudo aptitude install python3-numpy virtualenv libglib2.0-dev
# I'm not sure all of these are needed, since the later "pip install -r requirements.txt"
# brings some of them?

virtualenv -p /usr/bin/python3 wand
cd wand
. bin/activate
# now we have a safely isolated place to install some code, without
# interfering with other things

git clone --recursive https://github.com/GammaGames/kano-wand-demos.git
cd kano-wand-demos
pip install -r requirements.txt

sudo setcap 'cap_net_raw,cap_net_admin+eip' $VIRTUAL_ENV/lib/python3*/*-packages/bluepy/bluepy-helper

Other problems seen on the way?

• Linux: when the bluetooth services fail to restart my host adapter, I see this in the output of dmesg: Bluetooth: hci0: urb 000000005c....2c failed to resubmit (113)
  • Looks like I need to reboot.

Maybe you’re wondering…?

• Does the circuit board work without the “wand” part? Yes it works fine, but I expect there is a greater chance of damaging the electronics physically or by electrostatic discharge.
• Will you be using the wand to do something cool? Probably not. I like the idea of conducting some instruments with it, but I don’t have the musical skills and the wand itself is Going Away soon. I do have another BLE device to play with though.
• Are there alternatives to the Kano HPCW (wand)? Maybe. There is a DIY project and there are 3D mouse products such as the Air Mouse or SkyStream Air Mouse remote
• Do you understand quaternions? Not so much. I know they extend the complex numbers and I know where to look if I want to study them some more.
• How long will these software instructions remain valid? That depends on how much work people put into the projects. Sometimes code changes fast, sometimes it just sits there.