Last year, Coldplay came to Chile for the first time since 2007 (almost 10 years!)

At the entrance of the Stadium, they were giving a wristband called Xyloband.

Xylobands were invented for the Mylo Xyloto tour and they give them to the public to make the show even greater. These wristbands have lights that glow and they are controlled from the stage how they want to and when they want to.

Now, for the A Head Full of Dreams Tour, they upgraded them by adding RGB lights that can glow in any color they want to, making the whole concert experience even greater by making the stadium light up in red, or flash in every color possible.

You can read more about them at http://xylobandsusa.com/

In this (my first) Instructable, we’ll modify the board to light up again without (I hope) screwing up the original functionality.

Step 1: Tools & Materials

Tools you'll need:

Soldering iron
Screwdriver

Materials

Solder
Solder Paste
1x Arduino (you can use nano or uno, I want to use a nano but I haven’t bought it yet)
3 x PN2222a transistor (or any NPN transistor)
1 x 100 Ohm resistor
Jumper Cables
A really thin cable (I got it from an old PC connector cables)

Optional

Portable battery pack
A frame
Button

Step 2: How It Works, How Will It Be Hacked

Basically, a xyloband is an LED strip, attached to a microcontroller that turn on the lights when they receive certain messages through RF.

Getting the specific RF that is sent by the master controller is really hard and also it could be illegal because the Xylobands are a patented product, so, the only option available is to bypass the controller and making the LEDs glow using an external microcontroller such as Arduino.

So, the question is how to turn on the LEDs?

First of all, there are two types of RGB LEDs: Common cathode and common anode.

Common cathode are the ones that have 1 negative or ground pin and 3 positive terminals, one positive for each colour, and a negative one that works for all.

By the other hand, common anode are the opposite. They have 3 negative and 1 positive terminals. These are the ones used on the wristband

So basically we should link the end terminal from each colour to the GND pin and they’ll light up! Yes but… No.

If we only do that, we have some problems. The batteries included will run up; we can’t control the colours, only the basic ones will light up; and it wouldn’t be that fun!

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The “real” “hacking”

Opening up the little box, we find 3 batteries in battery holders. By taking the board off, first we see a little LED configuration and below we can find the whole circuit that controls everything. It is easy to see that it has some connectors for the strips and the microcontrollers (the black square chips).

Researching in the web I found THIS github repository from a guy that reverse engineered the whole board, showing which are the components and how the circuit goes. (Link to the schematic)

It really is an amazing job and it helps us to identify which is the best/easiest way to modify the board.

Going through the schematics, on the left, you can find the connector of the wrist strip. On the top, the connector for the inside LEDs. They are separated by colour .

Following the lines from each colour, there are a lot of different components such as coils and capacitors, but the important thing is that each colour, from both of the strips, join in points named as TPx (with the x corresponding to a number).

This way we find out that:

Red corresponds to TP5
Green corresponds to TP6
Blue corresponds to TP4

So, taking each point to GND will light up each colour and with the help of the Arduino PWM pins we’ll control them as we like.

Now comes the fun part.

Step 3: Opening Up the Case

Remove the 4 screws, and open the lid carefully watching how everything holds up together.

The first things you’ll see are 2 battery holders.

To remove the board, push both pieces that secures it to the case and pull a little from the band to help you release it. It isn’t necessary to push both at the same time.

Now you can remove the batteries and save them for the next concert. We won’t be using them since the arduino will power them up.

Remove the LED arrangement by releasing the connector (as shown in the picture).

Now we can access the board.

NOTE: if you like, you can take away the wristband led strip for the next part. Just remember the way they were connected.

Step 4: Soldering Cables.

Find the thinnest cables you can and solder about 20cm to the points in the board marked as TP4 TP5 and TP6. Also solder one to the middle big chunk of solder in the board (this is where we will power the LEDs)

Since the TP points are very small contact points, I reccomend to first put some solder paste, then melt some solder on every point, clean the solder paste and then, melting the solder blob on the board, put the cables in place.

Step 5: Reassembly

Reassemble the whole thing by plugging again the LEDs and making sure the cables dont interfere with anything.

IMPORTANT:

Before putting everything in the box again, assemble the box without the board (but don’t put the screws). Take a look on the sides. You will see that one of them has a little space where the cables can come out, so when you reassemble everything keep on your mind that they will go that way.

If the cables can’t come out through there, you can try making them go the same place the strip comes out of the case.

Step 6: Step 5: Connect the Circuit

Having closed the case, you can put together the circuit as shown in the schematic. I recommend using jumper wires that corresponds to each colour

Step 7: Testing the Circuit

Before plugging the arduino to your PC, disconnect the 5v wire from the arduino. This is for safety. You never remember what does the last code do.

Open up the arduino program and load the example program “Fade”.

This way we can make sure that everything is connected the way we want.

Once it loads to the board, you can reconnect the 5v cable and test each colour by changing the cable that goes from pin 9 to each one of the transistors.

"Hacking" a Xyloband With Arduino - Step #7
Download

Step 8: Program the Xylo to Do What You Want

After you make sure everything works as expected, you can now start programming the routines that you want the Xyloband to make.

Connect the Red, Green and Blue cables to the 9,10,11 pins on the arduino

I will leave the basic code that I used to make the Xyloband glow changing colours and i’ll be updating since it isn’t finished at all.

Also, I want to do… (the optional stuff :P)

Code Here

Step 9: Step 8: Optional Stuff

On the “Tools & Materials” section I mentioned that there were optional materials.

After all your work, you would want to show your back to work xyloband in a stylish way, so putting it into a frame would look awesome

I didn’t found the right frame to do it and I didn’t have the time to go and buy an Arduino Nano, but with that you can make a really good looking decoration for your home or room.

Also, you can add a button so you can change the colour routine that your band will do.