Tag Archive: physical computing

Sense Disorder

Sense disorder installed in Helsinki Taidehalli.

Sense disorder installed in Helsinki Taidehalli.

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. 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 was the 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 and with a minimal budget while still creating 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 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 of all, the price: at 16€ or cheaper they are way below the prices of neither of the alternatives. Audio wise VS1000 is 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. MP3 player shield you cannot connect straight to external amplifier without additional circuitry. Another nice thing 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 is not really able to read data stream that fast (wonder why this has not been documented anywhere)). I needed to use SoftwareSerial as I wanted to use only 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. 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.

Installation behind the scenes. The main logic board can be seen behind the light bulb at the left.

Installation behind the scenes. The main logic board can be seen behind the light bulb at the left.

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.

X-ray scan of the book.

X-ray scan of the book.

Openings is project by Axel Straschnoy. It is a book that reflects the intimate relationship of a reader with his/her books. As such the actual content of the book remains between the owner of the book and the book in it self, leaving mostly all technical details as a secret. We have however took some x-rays of the book to let you have a peek while considering whether you actually want to purchase it and reveal the secret. From x-rays you might recognize a Lilypad Arduino board. My task was to design and solder the electronics of the book.

Opening has been featured at the Finnish Museum of Photography, Galerie Xippas, Salon Light/SP at Galeria Vermelho, Koh-i-noor and the catalog of Ange Leccia et Le Pavillon at Musée Bourdelle.

Images © 2008 Axel Straschnoy

This is second gadget from my Best Wishes line. It is used for controlling playback of different audio samples via USB on a computer. It has an USB Arduino inside that sends serial data back to the computer. The computer is running a simple program which is using FMod Music & Sound Effects System. This basically means that you are making sound banks using FMod Designer. As you can run FMod dlls in all major OSs (Linux, Windows, OSX…), the implementation is platform independent. I have used both EEEPC 701 and PowerPC G4 as host computer and they both run fine.

It works like this: The potentiometer is actually a rotating switch which you use for choosing right sample bank. Switches are then used to start and stop samples in that bank. Buttons are used for fireing samples in the bank. LEDs show whether the sample is playing or not. It also has an option for delaying the updating of the position of the switches: You can choose which samples are going to be stopped and which fired at the next switch which you are performing by the black button (or footswitch) at the right.

The reason in using FMod is that it offers a variety of options of how events should trigger different sounds. You can randomly pick samples from a pool, have multilayered events etc… Also after you have built the project with it, you can run it from a lightweight C-program from command line. I usually don’t need any GUI at the computer side. I have to say that I would welcome a truely open source solution as a computer end. FMod is free for non-commercial use anyways so it is a good option for now. At the moment I am not that proud of the source code of my tiny program so I won’t be releasing it yet, but hopefully soon.