Addressable LED Strings In Your USB

December 24, 2019 by Lewin Day 4 Comments

WS2812Bs, or NeoPixels, or whatever else you call them brought full-color LEDs to maker projects a meter at a time in recent years. Hooked up to a microcontroller, they make creating vibrant, full-color glowables a cinch. They won’t work on their own though, and a some point you want to ditch the dev board and let the blinking stand on its own two feet. Enter the USB LED Otter.

This small square of PCB lets you plug an LED strip directly into a USB port. The PCB itself has four traces on the back that mate with any USB port, and three pads for soldering the strip’s ground, 5 V line, and data. An STM32F072 microcontroller serves as the brains of the operation, packing plenty of horsepower and full compatibility with USB 2.0.

Code is flashed to the chip over USB using Device Firmware Upgrade (DFU) and once written the strip can then be driven by jamming the string into a suitably powerful USB wall charger. The woman behind the build, [Jana Marie], has mentioned that Open Pixel Control could be implemented but that may be an exercise left to the reader.

It’s a useful little tool, and one that promises to do even more with a little more development. Whipping up a few boards should be an easy task for anyone with a reflow oven and a free weekend. Oh, and if you’re tired of the WS2812? There’s other addressable LEDs out there, too!

194 LED Ball Is Free-Form Soldering On Another Level

December 23, 2019 by Jenny List 20 Comments

We’ve all seen plenty of impressive free-form soldering in these pages, maybe some of us have even had a go ourselves. Using nothing but bare conductors, electronic components, and solder, complex and beautiful electronic sculptures can be created. But the latest free-form project from [Jiří Praus] takes the medium to a new level, as he’s taken no less than 194 bare surface-mount addressable LEDs and formed them into a perfect sphere supported by nothing more than soldered copper wire.

This feat was achieved with the aid of a 3D printed hemispherical jig with spaces for each LED, and each half was assembled in a marathon soldering session. Some significant fault-finding was required due to a few dry joints, and an ESP32 board and Li-Po cell were fitted in between the two halves as they were joined. The result is a triumph, a Christmas bauble like no other, and one which we aren’t sure we could manage to solder so well even on a good day.

If you recognise [Jiří ]’s work, it’s probably because we’ve featured several of his creations previously. It’s always difficult to pick a favorite, but the one which caught our eye the most was his fully functional freeform Arduino Uno.

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Optical Communication Using LEDs Alone

December 22, 2019 by Jenny List 53 Comments

We’re all used to the humble LED as a ubiquitous source of light, but how many of us are aware that these components can also be used as photodiodes? It’s something [Giovanni Blu Mitolo] takes us through as he demonstrates a simple data link using just a pair of LEDs and a couple of Arduinos. It’s a showing off his PJON networking layer, and while you’d need a bit more than a couple of LEDs on breadboards for a real-world application, we still think it’s a neat demonstration.

PJON itself is very much worth a look, being an implementation of a robust and error-tolerant network for Arduinos and other small microcontroller platforms. It has a variety of communication strategies for various different media, and as this LED demonstration shows, its strength is that it’s capable of working through media that other networks would balk at. Whether it’s controlling home automation through metal heating ducts or providing an alternative to LoRa at 433 MHz, it’s definitely worth a second look. We’ve mentioned it before, but remain surprised that we haven’t seen it more often since. Take a look, the video is below the break.

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Movie-Style Hacking With A Wall Of Glowing Hex

December 20, 2019 by Tom Nardi 21 Comments

Over the years, the media has managed to throw together some pretty ridiculous visual depictions of computer hacking. But perhaps none have gone as far down the road of obfuscation as The Matrix, where the most experienced hackers are able to extract information from a display of cascading green glyphs like a cyberpunk version of reading tea leaves. It’s absolutely ridiculous, with zero basis in reality.

Well, maybe not anymore. Taking a page from these outlandish visions of hacking, [Erik Bosman] has constructed a dedicated hex dump display out of fourteen segment alphanumeric LEDs that looks like it could be pulled from a movie set. But make no mistake, it’s more than just a pretty face. By cleverly varying the brightness of the individual characters, he’s managed to make his so-called “hexboard” completely usable despite the fact that everything’s the same color.

While he says the project is not quite at 100% yet, he’s already released the firmware, computer-side software, and even the PCB design files for anyone who might want to build their own version. Though as you might imagine, it’s quite a tall order.

The display is broken up into segments holding eight Houkem-5421 LED modules apiece, each with its own STM32F030F4 and two TC7258E LED controllers. The bill of materials on this one is a bit intimidating, but when the end result look this good it’s hard to complain.

To build a somewhat smaller version that also features a more retro vibe, you might consider doing something similar by chaining together vintage LED “bubble” displays.

A LED Cube Designed For Easy Assembly

December 15, 2019 by Gerrit Coetzee 6 Comments

LED cubes are mesmerizing and fun, but they’re usually a pain to build. Not so with [burkethos]’s cleanly designed cube.

Many cubes are put together in an elaborate sculptural style. Traditionally the leads of the LEDs are artistically bent and then hours are spent laboring over the future rainbow Borg cube. This build is more reminiscent of a motherboard or back plane design. The LEDs are surface mount units re-flowed onto a rake shaped PCB. At the base of each “rake” there’s a right angle male header. This is then soldered to base board which creates a reliable mechanical bond.

There are some downsides to this approach. For example, the PCBs occlude the LEDs at some viewing angles. However, this can be mitigated with careful placement in the room, or in one variation, mounting the cube at a different orientation so the rakes are horizontal rather than vertical.

Regardless, we appreciate this new take on an old project and can definitely see it having a more universal appeal than the kits that require a couple weeks of afternoons to finish.

Edge-Lit Ping Pong Paddle Lights Up The Fight

December 13, 2019 by Kristina Panos 7 Comments

[George] and his coworkers like to blow off a little lunchtime steam on the company ping pong table. We might do the same, except it’d just be us versus the wall, and most of the exercise would consist of bending over to pick the ball up off the floor. When he found a scrap piece of acrylic out in their shop, [George] got the bright idea to make an edge-lit paddle featuring the company’s logo.

Not only does the paddle look cool, it works pretty well, too, even though it’s heavier and has smooth surfaces compared to a standard paddle. To begin, [George] found a regulation-size paddle outline and imported it into SolidWorks, then designed all the necessary cuts for the LEDs and other electronics. He also designed and printed ergonomic grips to protect the goods.

Continuing the stuff-on-hand theme, [George] used through-hole LEDs and dug into the abundance of battery clips and springs they have lying around for designing prototypes, instead of making it all fancy with SMT LEDs and a rechargeable battery pack. Slip on those sweatbands, because we’re serving up the build video after the break.

We see more ping pong balls than paddles around here, and that’s probably because they make great LED diffusers.

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Reverse Engineering An Old Bus Display

December 11, 2019 by Tom Nardi 14 Comments

When his makerspace was gifted a pair of Luminator LED signs of the sort you might see on the front of a bus, [PWalsh] decided to pull one apart to see what made it tick. Along the way, he managed to reverse engineer its control protocol and replace its original control board with a WiFi-connected Raspberry Pi. Now they can use the LED signs to show whatever they want; no bus required.

As they were designed for automotive use, the signs were wired for 12 volts DC. So the first order of business was fitting it with an AC/DC converter so it could be plugged into the wall. After he measured the display’s current consumption, [PWalsh] estimated it’s maximum energy consumption and determined an old ATX computer power supply was more than up to the task.

With the sign happily running battery-free, he could begin figuring out how to talk to it. Noticing a MAX485 RS-485 converter on the PCB, gave a pretty good idea of what language it was speaking, and with the aid of his trusty oscilloscope, he was able to suss out the baud rate. A cheap USB to RS-485 converter was then wired in between the sign and its control board so he could sniff the data passing over the line.

From there, the final piece of the puzzle was studying the captured data and figuring out the protocol. [PWalsh] was able to identify packet headers and ASCII characters, and pretty soon knew enough about how the sign communicated that he was able to remove the control board entirely and just push text and images to it right from the Pi. He’s even made his framework available for anyone else who might have a similar piece of bus-signage laying around.

Even if you’re not looking to add one of these signs to your lab, this project is a fantastic example of protocol reverse engineering with low-cost tools and simple techniques. We always love to see the process broken down step by step like this, and our hat’s off to [PWalsh] for delivering the goods in a big way.

This isn’t the first time we’ve seen these sort of LED signs get the “Internet of Things” treatment, and if you’re content with a somewhat scaled down version, you could always just build your own display rather than waiting on the local public transit vehicle to get parted out.