In this project, I’m looking at two “ready to go” boards that provide touch sensitive inputs that can be used to play music. First is the Adafruit Circuit Playground Express and then on to the Bare Conductive Touch Board.
- For a more “DIY” approach, see Arduino MPR121 Touch Piano.
These are the links to tutorials and shops for these boards:
- Adafruit Circuit Playground Express – Priced at just under £25 from pimoroni or thepihut and others.
- Bare Conductive Touch Board – Priced at just under £50 from Bare Conductive.
Parts list
- Adafruit Circuit Playground Express
- Bare Conductive Touch Board
- Crocodile clip leads (optional)
- Miscellaneous conductive touch surfaces (optional)
- Amplification or audio output
The Circuit
Both boards could be used “as is” touching the pads directly, but you’ll probably get more out of them by linking the pads up to conductive objects using crocodile clips.
Adafruit’s Circuit Playground Express (CPX)
This is a much more general purpose education-oriented board, containing a wealth of sensors and output options, including full colour neopixel LEDs, 7 touch sensitive inputs, light, temperature and motion sensors, infrared in and out, a speaker and microphone. There are options for micro-USB or battery power.
It can be programmed using an online block-(think Scratch) style language, using Circuit Python or natively using the Arduino IDE.
It is relatively simple to use for touch applications with minimal setup and programming.
Bare Conductive Touch Board
This is “out of the box” ready for touch music applications as we’ll discuss more below.
It contains 12 touch sensitive inputs and built-in audio output hardware. It can also do MIDI and play samples from a micro SD card and can be reprogrammed using the Arduino IDE – it is based on the design for the Arduino Leonardo.
You can buy kits that come with conductive paint so that a range of specialist music and touch interfaces can be created.
Another nice feature of the Touch Board is that all the sensors and the audio are broken out onto header pins which makes using it in other projects quite easy. It also includes circuitry to support a LiPo battery with built-in charging from the micro-USB port.
The Code
Adafruit Circuit Playground Express
To get the Adafruit CPX playing music to touch, the simplest option is to fire up the online block-style programming environment. Here are the links you need:
Here is my code to play the notes C to B on the seven touch inputs A1 to A7.
You can run the code using the built-in simulator to make sure it does what you want it go. Then when ready to go, hit “download” and follow the instructions to drag the resulting “uf2” file to your actual circuit playground board to try it for real.
There are lots more projects to try on the Adafruit MakeCode pages here.
If you want to use it with the Arduino programming environment, here is how you do it.
Bare Conductive Touch Board
The “out of the box” option for the touch board is to use MP3 files that each play a “note” and load them onto the micro SD card (similar to my Arduino MP3 Piano) with the names TRACK000.mp3 up to TRACK011.mp3.
If you want to add MIDI, then full instructions for how to do it can be found here: Build a MIDI Piano.
There are lots of additional project ideas here on the Bare Conductive Resources pages.
If you want to use it with the Arduino programming environment, here is how you do it.
Closing Thoughts
These boards are both great and a very easy way to have a small number of touch inputs to get you playing music. Both are fully programmable and it looks like a relatively simple job to get them both acting as MIDI controllers.
If you want a general purpose, very STEM friendly, way to start making music, then the Adafruit Circuit Playground Express is a brilliant way to go with its 7 inputs, loads of other sensors, and a range of programming options.
If you want something more dedicated to music and audio applications then the Bare Conductive Touch Board has built-in audio support, 12 inputs and will support MIDI directly.
Kevin
Simple DIY Electronic Music Projects 