Category: Circuits

I have been wanting to play around with an ESP32-based micro for a while. Once I became comfortable with Adafruit’s microcontrollers and CircuitPython, I thought I’d try out some of their ESP32 offerings. I bought a few Airlift (ESP32) Featherwings to use with the Feather RP2040 boards I was experimenting with.

I’ve also been messing around with some WS2818 / NeoPixel LED 8×8 and 16×16 grids, so I thought it might be interesting to work on a web-based pixel display.

CircuitPython has some very handy libraries for building LED animations on strings or grids of WS / Neopixels. The Airlift ESP32 also has a library to create network clients and access points—surely this wouldn’t be too hard.

Here’s the shapes I used 3D print the parts:

(I really need to improve my enclosure design skills)

Something I’ve picked up from other people making an LED grid displays: Use a lattice grid and diffuser to create an even “pixel” instead of a bright point of light (depending on your tastes). It took a few tries to get the lattice to match nicely with the LED matrix circuit board. While most people use an acrylic diffuser, I just used a piece of card stock paper.

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Using the CircuitPython LED animations library, it was relatively easy to try out a variety of different LED matrix animation patterns. Building on the primitives in the library, I created additional functionality that supports text-based and sprite-based animations.

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With so many different patterns, sprites, and options to manage—I decided to use a web-based UI to handle the experience.

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The UI is served from the device itself. This turned out to be more challenging than you might think. I’ll do a separate post on serving a web-based UI while also running LED animations on the device.

Looking back at one of the first real projects I attempted which combined 3D printing and microprocessors. I received an Creality Ender 3 V2 a year ago and after playing around with some test prints, I wanted to try building some more interesting and complex projects. I came across this fiber optic LED lamp project via Instructables. It was just the right amount of 3D printing, microprocessors, and coding I was looking for at the time.

I tend to use components from Adafruit. They have a strong focus on learning. The guides and CircuitPython are great for getting started. So given the great set of instructions, my challenge was basically recreating the 3D models and porting to an Adafruit microprocessor running CircuitPython. The author already provided the 3D models as STLs and in Tinkercad (I also really like the simplicity of Tinkercad), but I wanted to reduce the number of fiber strands and make the lamp slightly smaller.

I figured out the general structure and process of the original model pieces by investigating the Tinkercad project. It didn’t take long to recreate some shapes that I could use to build the lamp structure.

CircuitPython has great support for individually addressable WS2818 / NeoPixel strands, so it was relatively simple to get some code working that would create some simple LED animations. I was using a Trinket M0, which is so tiny. I ran into some space issues where I couldn’t add all the animation support code I wanted onto the board. If I ever revisit this project, I’ll probably switch to a QT Py RP2040 or QT Py ESP32-S2, both of which have plenty of space, way more power, and the ESP32-S2 board would even allow for some network/web configuration UX.

Here are a few photos of the assembly process of the LEDs and optic fiber in the frame.

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The fiber optic cable is a “side glow” type used for decorations. It’s designed to create a glow.

Here is the base with the wires and a breadboard for the Trinket M0 (not inserted yet), along with a small button which can be used to change the animation modes.

The CircuitPython code is very simple and is available in a Github repo. I’m pretty happy with the finished project. Some things I’d want to address if I decide to work on a revision:

• Using CircuitPython doesn’t leave much room for user code on the Trinket M0, so I’d probably just bump up to one of the newer QT Py models. I’ll be able to add more animation modes too.
• Hot gluing the breadboard into the base isn’t sturdy enough. I’ll need to attach the next board with screws/nuts.
• Selecting animation modes using the button is not very friendly. If I bump up to a QT Py ESP32-S2, I’ll add a web setup UI.