Glow Flow Interactive LED Sculpture
It reacts to sound! It reacts to light! And it reacts to gravity! Presenting the
illusion of a bucket half-full of glowing liquid, it is Glow Flow
interactive LED sculpture. The Glow Flow project was my way of beta-testing a
pre-production Pixelblaze 3. Putting a unit through its paces, and report bugs
as I find them. The adventure started here with an LED strip still in a spool, under
control of the Pixelblaze as the brains of the operation. We see a stack of two
circuit boards here: the one on top is a sensor board, an optional
expansion for Pixelblaze. This particular one is an older version. Newer
ones have an audio line-in jack and a few other advancements. Below the sensor
board is a freshly baked Pixelblaze 3 taking in power via USB and sending
out LED control signals. The magic of Pixelblaze is on the software inside
simplifying the process of writing programs to control up to thousands of
individually addressable LED modules. This video won’t be covering the
calculations or the software side of Glow Flow very much, because math and
coding really doesn’t work well in a YouTube video. Please see the video
description for links to project write-up and Github repo with the code.
These bright and colourful LEDs are actually only running at 5% power. This
is enough for me to see their colors as I play with writing Pixelblaze patterns.
I decided to make the LED strip into a cylinder but I wanted LED modules to
line up vertically one loop to the next as they wound around the cylinder. This
meant I need a very specific diameter for my cylinder, so I designed and
printed a short piece to make sure the LEDs do indeed line up correctly. Once I
was confident I had the right diameter, I printed a full sized cylinder. Because
these LED modules could get warm, I printed a cylinder using PETG plastic
that is more resistant to heat than PLA plastic.
It took up almost the entire print volume of my 3D printer, and took over 26
hours to print. This cylinder forms the core for my project. Once printed, there
was another test fit to make sure LEDs do line up, then it was time to peel off
the protective paper from the double-sided tape and commit to
installing the strip on the cylinder. I designed a channel on the outside of
the cylinder for me to follow as I wind the LED. Following the channel
ensures even spacing as the helix wound around the cylinder. Once assembled, I ran
one of the pre-installed Pixelblaze patterns, just to make sure all the LED
modules are blinking and working correctly. But I wasn’t content with just
blinking, I wanted to create something that took advantage of Pixelblaze
ability to map individual LEDs to a location in three dimensions. To test
this pixel mapper functionality, I created a test program that sweeps
along each axis. When my array is mapped right, red will move in the positive
x-direction, green for positive Y, and blue for positive z.
After the three-dimensional axis were figured out, I started working on a Pixelblaze pattern that reacted to gravity using the accelerometer on the sensor
board. This involved conversion to polar coordinates space and some coordinate
transform matrix math. Details in the write-up, but we can see the result here.
Glow Flow is now a physically interactive piece.
This was the state I brought to the Hackaday Los Angeles July meetup for
presenting my work-in-progress. I had some kitchen paper towels taped on top
of my LEDs as a light diffuser. After the meet up, I started experimenting with
different ways to 3D print translucent light diffusers. Including a flat
featureless surface, horizontal ribbed surface, and a diamond pattern of
multiple thicknesses. I eventually decided to go with a flat surface so the
LEDs get all the attention, without any surface texture distraction. The diffuser
patterns and their support ribs form an external shell for Glow Flow. Inside the
cylinder, my placeholder USB power bank was replaced with a more powerful system
so I could drive the LEDs up to full power. These components mark the
successful completion of Glow Flow. We’ll end this video with a silly little Glow
Flow trick. As I mentioned at the start, Glow Flow reacts sound via microphone.
But here, I put Glow Flow on top of a subwoofer and turned up the volume. The
thumping is picked up by the accelerometer for an extra dimension in its reaction