The Idea

The idea came to me when the Feast of the Falls team was looking for ways to make the Feast an even more memorable event with community members adding their own little flair. We wanted some form of entertainment after the meal, and it seemed to me that giving people something to see that you just can’t see every day would fit the bill quite nicely. I hatched a plan to put together a wireless network of modules where each one controlled a number of lights programmed in some way to create a unique visual effect. The original thought (and I might still make this happen) is to float the modules and create a lit-up river with life-like luminescent creatures. For this I had to make them submersible, but that limitation proved too risky once I had the first few modules built. In the end the modules hung in trees, and the lights dangled like little droplets to create the eventual firefly effect.

The Pods

Following the original idea of submersible wireless modules, I came up with a fairly compact design based on a wireless device (a Zigbee transceiver), which is basically a general purpose communication device that can setup and maintain a connection to an ad-hoc wireless mesh network automatically. I set it up to receive commands that turn on and off pins on the device to light up several bright LEDs. Without getting into the details, the parts required to do this involved a custom designed circuit board and a fairly capable battery that could all fit into a compact container.

Each POD controls three green/yellow LED sets, to simulate three different fireflies attached to it. The device is powered by a camera battery designed for long life, cold temperature (in case it was submerged in water), and intermittent high power flashing. These devices could last days to weeks depending on the flash pattern.

The Control

To control the set of devices, I programmed the interface using a fairly powerful software package by a local, yet world renowned company, The MathWorks. Their Matlab software is generally used for mathematics, algorithms, instrument control, engineering, and many other applications. It might not have been the first logical choice for this project, but I have been using it at work, and it has a pretty easy graphical interface tool that made getting this up and running fairly quick and easy.

The most basic function besides figuring out and managing what pods are awake and connected, is running a firefly simulation. This means that I wanted to replicate the blink pattern from a real life firefly. Fortunately, the Museum of Science has this firefly watch site with data on blink patterns of known species. I programmed in the option to select a species, and the software sends out the blink pattern to any firefly pod selected, including multiple fireflies at the same time.

In the Field

The operation at the 2014 Feast of the Falls was a success for the most part, although I am still working out some kinks. It turned out to be a subtle background show with more attention brought to it as the night drew to a close and the surrounding woods became dark. At one point, I took manual control and essentially made one set of fireflies ‘dance’ to the rhythm of our singing Alderman Ted Hess-Mahan. One of the fireflies can be seen in the background here.

A total of eleven pods with three lights apiece were completed in time for the Feast. We set them up along the north and south sides of the long dining table.

And then there were squirrels. A day or so after the event, because of a business trip, I brought all of the pods down from the tree branches I placed them in. One cable appeared to have been tasted by one of those lovely grey furry friends.

Future Plans

I hope to have more than twenty Pods for the complete set, for a total of sixty individually controlled lights. More light shows are in the works, and you never really know when or where the Upper Falls Fireflies might show up!