For installation Super Ball my task was to implement a control unit for controlling a network of 49 1-Wire switches. Each switch is basically a programmable microcontroller though it was not necessary to actually program them, just alter value of one bit to switch a led connected to it on or off. In this article I’ll go through the design and building process on that very unit. Designing and building the light chain part of the installation (1-Wire network, led-units, balloon valves etc) was done by Martti Kalliala, Jenna Sutela and Jukka Rehu, not me, so I can’t cover them here.

First step in the process was to accomplish a hello world. I had one switch which I connected to the Arduino board and tried to make it blink. 1-Wire protocol is pretty straight forward but the command api of a switch was not. There is a ready made library for 1-Wire protocol. After some struggling I finally understood the order on 1-Wire commands to make the LED blink.

Next step was designing and building a box for Arduino. I bought sturdy Hammond Box for a case. We figured with Jenna that one potentiometer and couple of switches were enough for an interface. I also added connectors for power supply, fuse, USB (so there would not be any need to open the box for re-programming Arduino) and for light chain itself. Sadly I don’t have better images of the innards of the controller but the blurry pic above.

Testing the controller with the chain was a nightmare. It took hours of me to realise that innocent looking loops on a 150m light chain cable were actually blocking the dataflow inside the cable. The last switches in the chain were behaving badly and sometimes the whole chain could freeze. I added more code for error checking but when we finally did spread the cable more straight in Jenna’s studio, the chain started to behave. On the video above you see the before behaviour as two LEDs are on at the same moment. Belowe is the after behaviour. Although it can be hard to understand that it actually works as it should.

Video and images © 2008 Jenna Sutela