This is an installation I built for artists Paola Livorsi and Hilda Kozári based on their concept. Livorsi is sound artist and Kozári is known for her smell oriented pieces and this piece, to be used in workshops for children, combines these both aspects. The installation itself is a wooden box with four doors. Each door has different color, smell and sound attached to it. In this project I was in charge of industrial and electrical design, programming and carpentry. This explains why this post will be highly technically orientated.
This is first installation I designed with 3D modeling program SketchUp. The design challenge here was to come up with design that can be put together with minimal amount of tools with minimal amount of budget while still coming up with something fairly professional. After initial design I took the measurements to woodware shop and took a pile of ready cut plywood pieces back to my shop. After two days of glueing, drilling, sawing and painting and the box itself was ready.
Each door has a small magnet embedded to them. Magnet is triggering a reed magnet switch that is read by a custom built electronic player board. Board consists an Atmega328 microcontroller that is controlling four VS1000 audio modules. Microcontroller was programmed with Arduino IDE. I could have used computer with multichannel sound card, but as the application was fairly simple, building a stand alone audio player from scratch makes more sense. Compared to a computer it is cheaper, boots immediately and is more robust.
VS1000 audio modules are quite nice alternative to Wave Shields or MP3 Player Shields commonly used with Arduino in applications such this. First thing, the price: at 16€ or cheaper they are way below the prices of neither of the alternatives. Audio wise they are able to output CD-quality stereo signal, something that Wave shield is not able to do. VS1000 module also is equipped with different outputs for headphones and amplifiers while MP3 player shield you cannot connect straight to external amplifier without additional circuitry. One thing that is really nice is that the source code of the firmware is available (although not open source). This allows you to modify the player functions, or even implement your application with VS1000 module alone as it has an array of I/O pins itself. Interfacing with ATMega328 can be done using UART serial connection. Though I needed to bring down the default baud rate from 115200 as SoftwareSerial library really is not able to read connection that fast (wonder why this has not been documented anywhere). I needed to use SoftwareSerial as I wanted to only use one microcontroller for controlling all four players. Last thing to mention is that one can update the firmware and even use the memory of VS1000 chip as a tiny harddrive to store audio files. And updating can be done easily by using the memory card, no external hardware is required. If internal memory of the chip is not enough, audio can be read from memory card instead.
The box will hide two pairs of cheap computer speakers, giving each door its own speaker. This way we are really able to bind audio to a single door. There is also two energy saving lamps installed inside the box to allow the colors of filters installed on each hole to become visible. The electronic player card can be seen behind left lamp. For the smell, essential oils are applied to tiny pieces of felt that are hidden in the space between the doors and color filters (not really visible in this shot).
Arduino code for the AVR can be found here.