Fluid Simulation Pendant Teaches Lessons In Miniaturization

January 13, 2025 by 7 Comments

Some projects seem to take on a life of their own. You get an idea, design and prototype it, finally build the thing and — it’s good, but it’s not quite right. Back to the drawing board, version 2, still not perfect, lather, rinse, repeat. Pretty soon you look around to discover that you’ve built ten of them. Oops.

That seems to be the arc followed by [mitxela] with this very cool fluid simulation pendant. The idea is simple enough; create a piece of jewelry with a matrix of tiny LEDs that act like the pendant is full of liquid, sloshing about with the slightest movement. In practice, though, this project was filled with challenges. Surprisingly, [mitxela] doesn’t seem to number getting a fluid dynamics simulation running on a microcontroller among those problems, at least not to a great degree. Rather, the LED matrix seemed to cause the most problems, both in terms of laying it out on the 25-mm diameter PCB and how to address the LEDs with relatively limited GPIO on the STM32 microcontroller. The solution to both was diagonal charlieplexing, which reduces the number of vias needed for the 216-LED matrix and allows the 0402 to be densely packed, along with providing some tolerance for solder bridging.

And then there’s the metalworking heroics, which no [mitxela] project would be complete without. This seems to be where a lot of the revisions come from, as the gold-plated brass case kept not quite living up to expectations. The final version is a brass cup containing the LiR2450 rechargeable battery, a magnetic charging connector, and the main PCB, all sealed by a watch crystal. The fluid simulation is quite realistic and very responsive to the pendant’s position. The video below shows it in action along with a summary of the build.

If you want to catch up on [mitxela]’s back catalog of miniaturized builds, start with his amazing industrial ear adornments or these tiny matrix earrings. We’re also fond of his incredible shrinking MIDI builds. Continue reading “Fluid Simulation Pendant Teaches Lessons In Miniaturization” →

Electromechanical 7-Segment Display Is High Contrast Brilliance

January 13, 2025 by 11 Comments

The seven-segment display is most well known in LED form, but the concept isn’t tied to that format. You can build a seven-segment display out of moving parts, too. [tin-foil-hat] has achieved just that with a remarkably elegant design.

As you might expect, the build relies heavily on 3D-printed components—produced in white and black plastic to create a high-contrast display. It’s a simple choice that makes the display easy to read in a wide variety of lighting conditions, and far less fussy than toying with LEDs and diffusers and all that.

Actuation of each display segment is achieved electromagnetically. Effectively, each segment behaves like a flip dot, with the orientation controlled by energizing one of two electromagnets per segment. Controlling the electromagnets is an ESP32, which is hooked up to the various segments via a Darlington transistor array, with multiplexing used to minimize the number of IO pins required. A shift register was also employed to let the microcontroller easily drive four of these electromechanical digits.

It’s a simple build, well explained—and the final result is aesthetically pleasing. We’ve seen a few builds along these lines before, albeit using altogether different techniques. Lots of different techniques, in fact! Video after the break.

Continue reading “Electromechanical 7-Segment Display Is High Contrast Brilliance” →

Clever PCBs Straighten Out The Supercon SAO Badge

January 13, 2025 by No comments

When we decided that Simple Add-Ons (SAOs) would be the focus of Supercon 2024, it was clear the badge would need to feature more than just one or two of the requisite connectors. We finally settled on six ports, but figuring out the geometry of getting all those ports on the badge in such a way that the SAOs wouldn’t hit each other was a bit tricky. In early concept drawings the badge was just a big rectangle with the ports along the top, but it was too ugly.

In the end we went with a somewhat organic design — an electronic “flower” with the radially arranged SAOs forming the petals, but this meant that that none of the SAOs were in the traditional vertical orientation. Luckily, [Adrian Studer] designed a couple of PCBs that not only resolve this issue, but add a seventh SAO port for good measure.

In the project repository you’ll find two PCB designs. The first, “SAO Up” is essentially a little arm that turns the SAO port 90 degrees. This doesn’t exactly get them vertical, in fact, whether or not the new orientation is actually an improvement for the top two SAOs is perhaps debatable. But it definitely helps on the lower SAOs, which are essentially upside down in their original configuration.

The real star of the show is “SAO Bridge”, a wavy board that connects across the two midline SAO ports on the Supercon badge and turns it into a set of three (nearly) horizontal connectors across the front. The center port is particularly helpful in that it gives you a place to put unusually wide SAOs.

As a reminder the Supercon SAO badge, and the winners of the 2024 SAO Contest, will be making the trip across the pond for Hackaday Europe in just a few months. That means you’ve still got plenty of time to have a few of these CERN-OHL-P licensed boards made up.

Raspberry Pi Hack Chat With Eben Upton

January 13, 2025 by 18 Comments

Join us on Wednesday, January 15 at noon Pacific for the Raspberry Pi Hack Chat with Eben Upton!

join-hack-chatThe Hack Chat has been on an extended hiatus, but we’re back for 2025 and coming strong out of the gate! We’ve been trying to get Raspberry Pi co-founder and CEO Eben Upton on the chat for a while, but there was that whole thing of taking the company public that probably distracted him a wee bit. That’s fine though, because we know he loves getting in the trenches with the hacker community and talking about the things we all love to talk about. It’s not often that you get a chance for a one-on-one like this, so make sure you join us with all your Pi-related questions.

Our Hack Chats are live community events in the Hackaday.io Hack Chat group messaging. This week we’ll be sitting down on Wednesday, January 15 at 12:00 PM Pacific time. If time zones have you tied up, we have a handy time zone converter.

[Image credit: Sniper Zeta, CC BY-SA 4.0]

How Nyan Cat Was Ported To UEFI

January 13, 2025 by 13 Comments

The Unified Extensible Firmware Interface (UEFI) took over from the classical BIOS some years into the new millenium. It’s typically used for running a computer at the basic pre-OS level, and most of us don’t even notice it past boot time. However, you can do some neat things in this space—you can even port over Nyan Cat if you’re talented like [Cornelius].

That’s fun. Set your friend’s computer to boot into this instead of their OS by default and see how long it takes them to figure it out.

Yes, Nyan Cat is now available as a UEFI application, running via the EFI Simple Text Output Protocol. [Cornelius] approached this creation by first learning Rust, before progressing to the Hello World stage. Before long, the computer was booting up to display a simple text message with no OS required.

From there, creating the Nyan Cat animation required figuring out how to display it as a bunch of dancing characters, which is where the Simple Text Output Protocol came in. Nyan Cat was really the perfect animation for the UEFI environment, since its simple pixel art style was easily recreated with text. With a bit of work, the animation came together, with a remarkable resemblance to the original artwork.

All that’s missing is a routine to play the music over a PC speaker; only, those are hardly a thing anymore. A pity! In any case, if you’ve been cooking up your own nifty UEFI hacks, don’t hesitate to drop us a line!

Illustrated Kristina with an IBM Model M keyboard floating between her hands.

Keebin’ With Kristina: The One With The Holey And Wholly Expensive Keyboard

January 13, 2025 by 10 Comments

An Ultimate Hacking Keyboard (UHK) with DIY rainbow keycaps.
Image by [jwr] via reddit
The Ultimate Hacking Keyboard (UHK) line is, as the name suggests, a great choice for a lot of people. They’re each a toe-dip into the ergonomic waters with their split-ability and those beginner thumb clusters.

However, [jwr] was not completely satisfied and decided to make a custom set of keycaps. The idea was to create ‘caps without the “annoyingly abrasive texture of PBT”, that are larger than average for larger-than-average fingers. Finally, [jwr] wanted the Function row to tower over the number row a little, so these have a taller profile.

So, what are they made of? The look kind rubbery, don’t they? They are cast of pigmented polyurethane resin. First, [jwr] designed five molds in Fusion360, one for each row. Then it was time to machine master molds via CNC in foam tooling board. These were filled with silicone along with 3D-printed inserts, which produced silicone molds for casting keycaps four at a time in resin.

Continue reading “Keebin’ With Kristina: The One With The Holey And Wholly Expensive Keyboard” →

Using Audio Hardware To Drive Neopixels Super Fast

January 13, 2025 by 17 Comments

Here’s the thing about running large strings of Neopixels—also known as WS2812 addressable LEDs. You need to truck out a ton of data, and fast. There are a dozen different libraries out there to drive them already, but [Zorxx] decided to strike out with a new technique—using I2S hardware to get the job done. 

Fast!

Microcontrollers traditionally use I2S interfaces to output digital audio. However, I2s also just happens to be perfect for driving tons of addressable LEDs. At the lowest level, I2S hardware is really just flipping a serial data line really fast with a clock line and a word select line for good measure. If, instead of sound, you pipe a data stream for addressable LEDs to the I2S hardware, it will clock that data out just the same!

[Zorxx] figured that at with an ESP32 trucking out I2S data at a rate of 2.6 megabits per second on the ESP32,  it would be possible to update a string of 256 pixels in just 7.3 milliseconds. In other words, you could have a 16 by 16 grid updating at over 130 frames per second. Step up to 512 LEDs, and you can still run at almost 70 fps.

There’s some tricks to pulling this off, but it’s nothing you can’t figure out just by looking at the spec sheets for the WS2812B and the ESP32. Or, indeed, [Zorxx’s] helpful Github page. We’ve featured some other unorthodox methods of driving these LEDs before, too! Meanwhile, if you’ve got your own ideas on how to datablast at ever greater speeds, don’t hesitate to let us know!