I'll help you pick out a good toy to rescue, and then guide you through the process I used to successfully hack all of the buttons and switches to make something really cool and useful. We'll rip out the old, useless guts of the toy and replace it with a cheap microcontroller that is capable of sending and receiving MIDI messages to a PC, which will do the actual sound synthesis for us. I'll discuss the ins and outs of how to do this using code, and hopefully help you improve your project-making skills along the way!
Example of finished MIDI controller
What is a MIDI controller?
The Musical Instrument Digital Interface (MIDI) protocol was developed by professional audio technicians as a way for their various electronic devices (drum machines, synthesizers, samplers and more) to communicate by sending messages back and forth. Messages like, “play this musical note” and “we’re now in the 3rd beat of the 2nd measure” are transmitted between devices to help keep all of the devices in sync and reduce the amount of work that people need to do.
Every musical device out there today can be classified as a specific type of device, such as a sequencer, synthesizer, sampler, controller or others. In this article, we will be converting a toy into a MIDI controller. A MIDI controller typically has no ability to produce any noise or manage musical notes into a piece of a music. Instead, it’s more like a keyboard or a mouse; they tell a more intelligent device about changes in it’s own systems (i.e. “user pressed the A button”).
You can learn a great deal more about the MIDI using a variety of resources. Since MIDI has been around for quite some time, there is a great deal of information available on the internet, such as:
For personal reference, I ordered the following book and have been very happy with it: http://www.amazon.com/MIDI-Power-Comprehensive-Robert-Guerin/dp/1598630849/
Step 1: Acquiring a suitable toy
What to look for
- Relatively low number of buttons. Less than a dozen is a good idea.
- Very few or no sliders or knobs. You can utilize these in a MIDI controller, I just won't cover it here
- A big enough enclosure to accommodate a few extra wires and a Teensy microcontroller
Where to find a good toy
Don’t over-think this process too much; if its a toy that has electronics inside of it, you can convert it into a MIDI controller! If you’re flipping through pages of Google results or Amazon products trying to find the toy that is “just right”, stop it. The best place to get fantastic toys from is your local Goodwill, Salvation Army or other local thrift store, and are they only places I like to go to when looking for toys. Buying a brand new retail toy from Wal-Mart will only contribute to wasteful consumerism and put a hole in your wallet.
The toy guitar that I will be using for demonstration in this article was purchased from my local Salvation Army for $1.95! Thousands upon thousands of cheap toys are thrown out all the time by families all over the country, usually for trivial reasons like cracks or a broken button. Believe it or not, the most common cause for toys being thrown out is simply that the batteries are dead!
Introducing my toy guitar
I stumbled across this beauty one day at my local Salvation Army, and knew I had to have it as soon as I found it. In fact, I decided to do this article after I found this guitar, because I thought it would make such a cool MIDI instrument! The guitar features a large variety of pieces that can be pressed, spun, rocked and tilted. It even includes some neat lights and unusual features (like that gray wheel at the bottom – it spins!). When I brought it home, I quickly found out why it was discarded; there was a crack in the plastic of the fretboard, making the whole thing flex in odd ways. Furthermore, the batteries were dead. I applied super-glue to crack and removed the batteries, and the guitar was good as new!