Harry Potter Spell

I did not see this page and I built my own wand from some paper and straws in about 6 minutes. I then did some research on the Universal interactive wands and their machines there are many articles like this (though this one is my favorite). I had not yet discovered this article so I went on Quora and found out a lot. I tried the simple tinfoil approach several times at Universal (mainly the aquamenti place) and IT NEVER WORKED! I think this is because tinfoil is crinkly and it reflects the IR rays in many directions so the tinfoil wand tip never makes a full connection to the sensor. I liked your idea for the Wii thing! I will have to try it when I get home!

We just did our first trip to Orlando and I was hoping their might be some way to bring the magic home. I love this project, but I’m also a Mac guy with not much access to PCs. I’d be very interested in trying to adapt this project to Macs, Raspberry Pi, or Arduino devices. Any ideas on where to get started? I think you PC code is in C#, right? I did some C# programming years ago, but I’m not really current. I have so many questions:

I see one option is to use the Little Bits Arduino, if you do that I assume the PC code is still required for CloudBit and connectivity to the WiiMote from the PC? I wasn’t clear on this relationship.

I did find this Instructibles project for hacking the IR sensor from the Wiimote right to an Arduino, http://www.instructables.com/id/Wii-Remote-IR-Camera-Hack/ Is the IR sensor the only piece of the WiiMote (except the BT connection) that’s needed fro this project?

It’d be great if the PC code could be replaced with something smaller that could possibly be embedded. If so I could imagine being able to create all sorts of items that could be wand controlled.

You might try using reflective tape, like this to bounce back the IR. This is how Jonny Lee was able to do finger tracking from a Wiimote by bouncing back the IR emitted from the Wii sensor bar, http://johnnylee.net/projects/wii/

Hi all,
I just got back from the parks and was scouring the web for ways to bring the ‘magic’ of the wands home. I can’t wait to get this project rolling. I have successfully paired the wiimote and was able to run the wiiwandz app on my laptop. I can’t wait to get my littlebits kits this week and dig into that part.


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How did your experiment at Universal go?

:frowning: I left my littleBits in the hotel.

Hmm, yeah, I was not very satisfied with using tinfoil for my project. If you look at the reflection on the screen for the Wii, or on the PC for the software I made, you’ll see that the signal jumps around. It’s just not smooth enough. A mirror for the Wii project also won’t work, because the Wii has more than one IR bulb, but if you cover the other one up, it might do just fine. Since the bulbs are far away at Orlando, IR reflective tape or a mirror might work (on the tip of a finger or a wand). The problem with the mirror is that you have to get the angle of reflection just right.

Unfortunately, the PC code is NOT trivial. It performs the following functions:

  1. Communicates with the paired Wiimote to receive the X, Y wand positions from the IR reflection
  2. Shows the trail of the wand movements to help the user see what movements they are making
  3. Detects when the wand has paused so it can check if a correct movement was made (IIRC - either the comparison is constant, or it waits for a pause, but I can’t remember)
  4. Converts the last 2 seconds of points into a matrix of X, Y positions
  5. Does some matrix calculations against a neural network and makes a “best guess” as to which spell was cast
  6. Since it always returns with some answer, it only approves if the confidence level is above a certain threshold
  7. Even so, it does some other reality checks (how far away is the start point from the end point, relative to the other movements, and in which general direction did the end point go relative to the start?) to filter out bad guesses
  8. If there is a successful match AND the match is configured to call the CloudBit, the software sends the message out via the web

So, responding to your idea to do it for the Mac (I WISH I had - I own a Mac!), the first thing you’d need is a library for pairing communicating with a Wiimote on the Mac. I did actually find some in my research for this project (http://sourceforge.net/projects/darwiin-remote/), but learning Objective-C was a little much for me at the time. If you go this route let me know and I’ll help! I don’t know what good I’ll be with the interface, but I can help you understand and translate the math.

Now, it’s probably possible to go straight from an IR camera to the Arduino, or at the very least a Raspberry Pi. If you got this way, you can actually do without the CloudBit (and the Internet) altogether - great for a portable toy! In either case, you’ll need to rewrite steps 3 through 7 above to be done right on that board. I’m not sure if an Arduino is powerful enough, but there’s a good chance it is. The C# project uses threading, but it’s just because the display and the input would trip all over each other. What you’ll lose is the feedback to the person, so they won’t understand why it’s not working, nor how close they are to getting it right (in Orlando they have the same problem - that’s why there are nice park Wizards wandering from spell to spell showing kids what they’re doing wrong).

Keep in touch, and I’ll do what I can to help!

(Btw, I’ve got this working on Android now, but without the wand :frowning: )

Bummer! We were hoping for more data. Looks like I’ll need to find another excuse to go “investigate” again :wink: Did you guys have a good time?

Yes, we did. We also enjoyed the Magic Kingdom, where we found a lot of project inspiration - creative lighting, robotics, and theatrics.

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Thanks of the reply and all the great info. Funny you mention the Darwiin-Remote project as that is what I have been using for some of my tests. I may take you up on the offer to help understanding and translating the math. I actually found a possible camera system for the Arduino/Raspberry Pi but I need to look into some IR filters and firmware changes to possibly make it work well for this application.

One other question for you. Have you played around with other IR light sources? I experimented like you with a security camera light, but I couldn’t get the wand to seem to reflect that back. I’m hoping to find a source that has a bit more range than the Wii bar. I’m open to ideas.

I haven’t figured out anything better, so if you do, let me know! I tried two different security cameras (including one mega 60-LED one), and got pretty much nothing. If you point the camera LEDs right at the sensor, it picks them up (and a TV remote will work as a direct source, too), so it must be with the reflection frequency. Another option would be to stick some reflective IR tape on the tip, but I don’t have any…

I’ve spent some time scouring the internet for some information about the Wii remote and the Wii IR array (sensor bar). It looks like 940nm wavelength is what you need from your IR leds. The leds in the official Wii sensor bar are pretty dim, so I’ve been told that you can make an IR array using 3 or so 1W 940nm IR leds to extend the distance.

I briefly tried using a Wii whiteboarding ‘pen’ that I got this week and it seemed to have a little more range. This might be interesting for making your own custom wand to work with the Wiimote.

Thanks for your response. I thought I had read the Wii used 850nm IR LEDs, but maybe my info was incorrect. Do you have a source for your info? I’m looking at adapting a PIXY to connect with the Arduino or Raspberry Pi. I have an IR Adapter Kit from IR-LOCK, http://irlock.com/products/ir-lock-filter-for-pixy, but I’m not sure what wavelength the included IR LEDS are. I’ll play around a bit and try to post my findings here.

This is one of the sources I discovered. http://wiicanetouchgraphic.blogspot.com/2009/03/wii-remote-ir-sensitivity.html

I also read through the posts on here: http://www.wiimoteproject.com/ir-pens/what-is-the-wiimote's-preferred-peak-wavelength/


Good Day @maccast,

The IR-LOCK filter is best-suited for 940nm LEDs. At IR-LOCK, we are very ‘picky’ about which LEDs we use, but you will get descent performance with most LEDs listed as ‘940nm’.


Thanks Thomas. Since you are “picky” is there an LED you specifically recommend? I know you have your own high power units, but for my application I really just need one high-power LED, not an array, so what would you recommend?

Hi all,

Just wanted to share my version of Specialis Revelio…

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Hello @timothy_high, @cskuo, @maccast, @bill, @katlup, @lujab2004, et al. :smile:

I posted another kind of Harry Potter themed project. Below you will find Tom Riddle’s diary, which is protected by an enchantment that can only be broken with a magic wand (or household remote). I hope you like it! :slight_smile: :sparkles:
Harry Potter Magic Diary

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That is great. Thanks for sharing. Have you tried putting the IR emitter on the “book” side and seeing if it can reflect back from the “bead” in the Universal Studios Harry Potter wands?

Just an update. I still want to work on this project, but life and paid coding projects have taken precedence for now. hope to get back to experimenting with this again soon. I have many of the pieces I think I need to get this woking on Arduino or Raspberry Pi, but I’ll likely start by trying to get something going on the Mac first.