Electromyography Hack Chat

January 17, 2022 by Dan Maloney No comments

Join us on Wednesday, January 19 at noon Pacific as we kick off the 2022 Hack Chat season with the Electromyography Hack Chat with hut!

It’s one of the simplest acts most people can perform, but just wiggling your finger is a vastly complex process under the hood. Once you consciously decide to move your digit, a cascade of electrochemical reactions courses from the brain down the spinal cord and along nerves to reach the muscles fibers of the forearm, where still more reactions occur to stimulate the muscle fibers and cause them to contract, setting that finger to wiggling.

The electrical activity going on inside you while you’re moving your muscles is actually strong enough to make it to the skin, and is detectable using electromyography, or EMG. But just because a signal exists doesn’t mean it’s trivial to make use of. Teasing a usable signal from one muscle group amidst the noise from everything else going on in a human body can be a chore, but not an insurmountable one, even for the home gamer.

To make EMG a little easier, our host for this Hack Chat, hut, has been hard at work on PsyLink, a line of prototype EMG interfaces that can be used to detect muscle movements and use them to control whatever you want. In this Hack Chat, we’ll dive into EMG in general and PsyLink in particular, and find out how to put our muscles to work for something other than wiggling our fingers.

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 19 at 12:00 PM Pacific time. If time zones have you tied up, we have a handy time zone converter.

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Christmas Tree PCB Just The Trick For Festive Glee

December 15, 2021 by Lewin Day 3 Comments

The festive season is often as good a reason as any to get out the tools and whip up a fun little project. [Simon] wanted a little tchotchke to give out for the holidays, so they whipped up a Christmas tree PCB that’s actually Arduino-compatible.

It’s a forward-looking project, complete with USB-C connector, future-proofing it for some time until yet another connector standard comes along. When plugged in, like many similar projects, it blinks some APA102 LEDs in a festive way. The PCB joins in on the fun, with white silkscreen baubles augmented by golden ones created by gaps in the soldermask.

An ATTiny167 is the brains of the operation, using the Micronucleus bootloader in a similar configuration to the DigiSpark Pro development board. It relies on a bit-banged low-speed USB interface for programming, but the functionality is largely transparent to the end user. It can readily be programmed from within the Arduino IDE.

It’s not an advanced project by any means, but is a cute giveaway piece which can make a good impression in much the same way as a fancy PCB business card. It could also serve as an easy tool for introducing new makers to working with addressable LEDs. Meanwhile, if you’ve been cooking up your own holiday projects in the lab, don’t hesitate to drop us a line!

Sound-Reactive Mannequin Arms Make For Creepy Lounge Decor

December 9, 2021 by Lewin Day 8 Comments

Music visualizers were all the rage back in era of Winamp and Windows Media Player. They’re even cooler when they don’t just live on your computer screen, though, as [Emily Velasco’s] latest project demonstrates.

The build consists of two mannequin arms on a board mounted on the wall. The arms were sourced for just $5 from a Sears that went out of business, and originally fastened to the mannequin thanks to magnets inside. Thus, putting two steel plates on the board allowed the arms to be attached, and they can be freely arranged as [Emily] sees fit.

The ESP32-based Pixelblaze LED controller serves as the brains of the operation, controlling LEDs mounted inside the arms themselves. Using a dedicated controller makes working with addressable LEDs a cinch. As a further bonus, the board serves up a web interface, allowing patterns to be changed without having to hook up a cable to the device. Meanwhile, a sensor board inside the arms uses a microphone to enable the light show to react to sound and music.

It’s one of the more obscure uses for an old mannequin, but definitely one that appeals to our love of everything that flickers and glows. It’s a build very much up [Emily’s] alley; as a prolific maker, she loves to build weird and wonderful creations, as shared during her talk at the 2019 Hackaday Superconference. Video after the break.

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Simple But Stylish Numitron Clock Can Display Time, Date And Temperature

November 22, 2021 by Robin Kearey 6 Comments

While it seems like Nixie tubes get all the attention when it comes to making retro-style displays, there are plenty of other display technologies that can make a good-looking retro design. Take the Numitron tube: introduced by RCA in the early 1970s, these display tubes might look superficially similar to Nixies but work in a completely different way. The Numitron uses incandescent elements that make up seven-segment displays.

The main advantage Numitrons have over Nixes is that they don’t require a high-voltage supply, which makes them much easier to hook up to modern low-voltage electronics. [mircemk] used this to his advantage when he built a simple clock using four numitrons that can display the time, the date, and the ambient temperature.

The brains of the device are formed by an Arduino Nano coupled with a DS3231 battery-backed real-time clock module. For now, the time has to be synchronized by connecting the Arduino to a PC and reprogramming it, but [mircemk] has plans to update the design with pushbuttons to allow the user to set the time manually.

Four shift registers are all that’s needed to interface the microcontroller to the display tubes, thanks to their low-voltage operation. They do need quite a lot of current, so [mircemk] used the high-power TPIC6C595 instead of a regular 74HC595 chip. We wonder if the tubes’ high power consumption could be the reason why the temperature in his lab seems to hover around 30 °C.

A simple but stylish plastic enclosure completes the design. Since Numitron tubes are relatively low-cost and no other specialized components are needed, this could be one of the cheapest and easiest ways to make a retro display tube clock. Although we’ve seen a couple of Numitron clocks and even watches before, today’s build is a great example of how simple such a design can actually be. Continue reading “Simple But Stylish Numitron Clock Can Display Time, Date And Temperature” →

Magic In VR That Depends On Your Actual State Of Mind

November 21, 2021 by Donald Papp 10 Comments

[Cangar]’s excitement is palpable in his release of a working brain-computer interface (BCI) mod for Skyrim VR, in which the magic system in the game is modified so that spell effectiveness is significantly boosted when the player is in a focused mental state. [Cangar] isn’t just messing around, either. He’s a neuroscientist whose research focuses on assessing mental states during task performance. Luckily for us, he’s also an enthusiastic VR gamer, and this project of his has several interesting aspects that he’s happy to show off in a couple of videos.

User wearing VR headset — The Muse 2 fits under the VR headset easily.

It all starts with the player wearing a Muse 2 meditation device; a type of passive, off-the-shelf electroencephalography (EEG) unit aimed primarily at guiding a user towards better relaxation and focus. [Cangar] reads data using the Brainflow library and processes it into a final value on a scale between “not focused” and “focused”. [Cangar] makes a point of explaining that his system ultimately has the goal of modeling the player’s state of mind, which is different from modeling just the brain activity. As such, motion data is considered as well, and holding still confers a small bonus to the process.

How is this data actually used in the game? In VR, this “focus” value is shown as a small bar on the player’s wrist, and spell effectiveness (for example, damage for attack spells) scales along with the size of the bar. When the bar is full a player would be very powerful, with spells doing double damage. If the bar is empty, spells will do little to no damage.

[Cangar] demonstrates the mod in two videos (both embedded below), but you won’t see him blasting enemies with fireballs. Presumably, VR gamers already know what that looks like, so what he does instead is explain how the system looks and works (first video, cued to 4:12), and in the second, he video demonstrates how the focus meter changes depending on his activity and mental state.

The results look exciting, and the potential uses of a system like this are pretty interesting to think about. Taking a few deep breaths and calming one’s body and mind before launching a magical attack will have a tangible effect in the world, and because things rarely go according to plan, there is also a clear survival benefit to learning to focus while under pressure. But if a brain monitor isn’t your cup of tea, maybe consider a leisurely bike ride through Skyrim, instead.

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A breadboard filled with logic chips and wiring

SPAM-1 Is A Well-Documented Discrete CPU With An Impressive Software Library

November 6, 2021 by Robin Kearey 16 Comments

Here at Hackaday we love projects that are so well-documented that you can spend days reading up on what the designer has achieved. [John Lonergan] didn’t disappoint when he designed the SPAM-1, an 8-bit CPU built from discrete logic gates. His detailed log contains a wealth of information on such things as designing opcodes, optimizing program counter logic, running a digital simulation, as well as his thoughts on microcode design. The sheer volume of it may be a bit off-putting to beginners, so it might be best to start with the video series that describes the architecture and goes into detail on several sub-blocks.

The design has changed a bit since [John] first started on the project, as he decided to add more and more features, but the final result is a well-thought out architecture that keeps the simplicity needed for discrete hardware but still has enough features to keep it interesting for seasoned CPU aficionados. The instruction size is rather large (48 bits) to simplify the instruction decoding at the expense of larger code size. Conditional jump instructions are not present; instead, all instructions have an optional control flag to make them conditional, a feature inspired by the ARM instruction set.

Once the design was mature enough, [John] modelled the entire thing in Verilog and simulated his design to verify correct operation and to check the timings, estimating it to be workable up to 5 MHz or so. A large stack of breadboards and DIP chips from the 74xx series then brought the design to life.

Not content with simply designing, simulating and implementing a custom CPU in hardware, [John] also spent significant effort on the software side of things, writing an assembler and even a C-like compiler for the SPAM-1 platform. And if that wasn’t enough, he also added an emulator for the classic CHIP-8 language, which allows it to run existing programs like Pong and Tetris. Input and output for all this software is mostly through a UART connection to a PC. A VGA interface is still on [John]’s to-do list, but he did build an adapter to connect a classic NES controller to the system.

The SPAM-1 is a worthy addition to the long list of discrete-logic CPUs we’ve seen here, such as this breadboard computer running a UNIX-like OS or this minimalistic one. If you’d like to see one that implements an existing instruction set, try this homebrew RISC-V computer.

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A miniature iMac clone running MacOS Monterey

Cute Little IMac Clone Runs MacOS On A Tiny Screen

November 2, 2021 by Robin Kearey 6 Comments

Building a Hackintosh – a non-Apple computer running MacOS – has been a favorite pastime of hackers ever since Apple made the switch from PowerPC to Intel hardware. Though usually built from commodity PC parts, some have successfully installed Apple’s OS onto various kinds of Intel-based single-board computers. [iketsj] used such a board to build a cute little Hackintosh, and apparently decided that if he was going to imitate Apple’s hardware, he might as well take some clues from their industrial design. The result can be seen in the video (embedded below) where [Ike] demonstrates a tiny iMac-like device with a 5″ LCD screen.

The brains of this cute little all-in-one are a Lattepanda, which is a compact board containing an Intel CPU, a few GB of RAM and lots of I/O interfaces. [Ike] completed it with a 256 GB SSD, a WiFi/Bluetooth adapter and the aforementioned LCD, which displays 800×480 pixels and receives its image through the mainboard’s HDMI interface.

The case is a 3D-printed design that vaguely resembles a miniaturized iMac all-in-one computer. The back contains openings for a couple of USB connectors, a 3.5 mm headphone jack and even an Ethernet port for serious networking. A pair of speakers is neatly tucked away below the display, enabling stereo sound even without headphones.

The computer boots up MacOS Monterey just like a real iMac would, just with a much smaller display. [Ike] is the first to admit that it’s not the most practical thing in the world, but that he would go out and use it in a coffee shop “just for the lulz”. And we agree that’s a great reason to take your hacks outside.

[Ike] built a portable Hackintosh before, and we’ve seen some pretty impressive MacOS builds, like this Mini iMac G4, a beautiful Mac Pro replica in a trash can, and even a hackintosh built inside an actual Mac Pro case.

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