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Hackaday Links: October 23, 2022

There were strange doings this week as Dallas-Forth Worth Airport in Texas experienced two consecutive days of GPS outages. The problem first cropped up on the 17th, as the Federal Aviation Administration sent out an automated notice that GPS reception was “unreliable” within 40 nautical miles of DFW, an area that includes at least ten other airports. One runway at DFW, runway 35R, was actually closed for a while because of the anomaly. According to GPSjam.org — because of course someone built a global mapping app to track GPS coverage — the outage only got worse the next day, both spreading geographically and worsening in some areas. Some have noted that the area of the outage abuts Fort Hood, one of the largest military installations in the country, but there doesn’t appear to be any connection to military operations. The outage ended abruptly at around 11:00 PM local time on the 19th, and there’s still no word about what caused it. Loss of GPS isn’t exactly a “game over” problem for modern aviation, but it certainly is a problem, and at the very least it points out how easy the system is to break, either accidentally or intentionally.

In other air travel news, almost as quickly as Lufthansa appeared to ban the use of Apple AirTags in checked baggage, the airline reversed course on the decision. The original decision was supposed to have been based on “an abundance of caution” regarding the potential for disaster from its low-power transmitters, or should a stowed AirTag’s CR2032 battery explode. But as it turns out, the Luftfahrt-Bundesamt, the German civil aviation authority, agreed with the company’s further assessment that the tags pose little risk, green-lighting their return to the cargo compartment. What luck! The original ban totally didn’t have anything to do with the fact that passengers were shaming Lufthansa online by tracking their bags with AirTags while the company claimed they couldn’t locate them, and the sudden reversal is unrelated to the bad taste this left in passengers’ mouths. Of course, the reversal only opened the door to more adventures in AirTag luggage tracking, so that’s fun.

Energy prices are much on everyone’s mind these days, but the scale of the problem is somewhat a matter of perspective. Take, for instance, the European Organization for Nuclear Research (CERN), which runs a little thing known as the Large Hadron Collider, a 27-kilometer-long machine that smashes atoms together to delve into the mysteries of physics. In an average year, CERN uses 1.3 terawatt-hours of electricity to run the LHC and its associated equipment. Technically, this is what’s known as a hell of a lot of electricity, and given the current energy issues in Europe, CERN has agreed to shut down the LHC a bit early this year, shutting down in late November instead of the usual mid-December halt. What’s more, CERN has agreed to reduce usage by 20% next year, which will increase scientific competition for beamtime on the LHC. There’s only so much CERN can do to reduce the LHC’s usage, though — the cryogenic plant to cool the superconducting magnets draws a whopping 27 megawatts, and has to be kept going to prevent the magnets from quenching.

And finally, as if the COVID-19 pandemic hasn’t been weird enough, the fact that it has left in its wake survivors whose sense of smell is compromised is alarming. Our daily ritual during the height of the pandemic was to open up a jar of peanut butter and take a whiff, figuring that even the slightest attenuation of the smell would serve as an early warning system for symptom onset. Thankfully, the alarm hasn’t been tripped, but we know more than a few people who now suffer from what appears to be permanent anosmia. It’s no joke — losing one’s sense of smell can be downright dangerous; think “gas leak” or “spoiled food.” So it was with interest that we spied an article about a neuroprosthetic nose that might one day let the nasally challenged smell again. The idea is to use an array of chemical sensors to stimulate an array of electrodes implanted near the olfactory bulb. It’s an interesting idea, and the article provides a lot of fascinating details on how the olfactory sense actually works.

Look Inside This “Meditation Headband” And Integrate It Into Your Own Projects

Muse makes a variety of wearable devices aimed at measuring brain and body activity, and [Becky Stern] did a detailed teardown of the Muse S model, revealing what goes on inside the device.

The Muse S is a soft, sleep-friendly biofeedback wearable mounted on silver-plated fabric. Not only does [Becky] tear it down, but she provides loads of magnified images and even has it CT scanned. The headband has conductive fabric embedded into it, and the core of the device is stuffed with three separate PCBs that get pretty thoroughly scrutinized.

While the Muse S is sold mainly as a meditation aid and works with a companion app, there is, fortunately, no need to go digging around with a screwdriver and soldering iron to integrate it into other projects. The Muse S is supported by the Brainflow project which opens it up to different applications. Brainflow is a library intended to obtain, parse, and analyze EEG, EMG, ECG, and other kinds of data from biosensors.

If you think Muse and Brainflow sound familiar, that might be because of another project we featured that integrated a Muse 2 and Brainflow with Skyrim VR, creating a magic system whose effectiveness depends on the player’s state of mind. Good things happen when hardware and software are accessible to users, after all.

You can watch a video tour of the teardown in the video, embedded just under the page break.

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A sequence of pictures with arrows between each other. This picture shows a Wokwi (Fritzing-like) diagram with logic gates, going to a chip shot, going to a panel of chipsGA footprint on a KiCad PCB render with DIP switches and LEDs around the breakout. Under the sequence, it says: "Tiny Tapeout! Demystifying microchip design and manufacture"

Design Your Own Chip With TinyTapeout

When hackers found and developed ways to order PCBs on the cheap, it revolutionized the way we create. Accessible 3D printing brought us entire new areas to create things. [Matt Venn] is one of the people at the forefront of hackers designing our own silicon, and we’ve covered plenty of his research over the years. His latest effort to involve the hacker community, TinyTapeout, makes chip design accessible to newcomers – the bar is as low as arranging logic gates on a web browser page.

Six chip shots shown, with various densities of gates being used - some use a little, and some use a the entire area given.
Just six of the designs submitted, with varying complexity

For this, [Matt] worked with people like [Uri Shaked] of Wokwi fame, [Sylvain “tnt” Munaut], [jix], and a few others. Together, they created all the tooling necessary, and most importantly, a pipeline where your logic gate-based design in Wokwi gets compiled into a block ready to be put into silicon, with even simulations and compile-time verification for common mistakes. As a result, the design process is remarkably straightforward, to the point where a 9-year-old kid can do it. If you wanted, you could submit your Verilog, too!

The first round of TinyTapeout had a deadline in the first days of September and brought 152 entries together – just in time for an Efabless shuttle submission. All of these designs were put on a single instance of a chip, that will be fabbed in quantity, tested, soldered onto breakouts, and mailed out to individual participants. In this way, everyone will be getting everyone’s design, but thanks to the on-chip muxing hardware, they’re able to switch between designs using on-breakout DIP switches.

More after the break…

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Protected Mode On A Z80! (Almost)

The microprocessor feature which probably most enables the computing experience we take for granted today is protected mode. A chip with the required hardware can run individual software processes in their own environments, enabling multitasking and isolation between processes. Older CPUs lacked this feature, meaning that all the resources were available to all software. [Andy Hu] has done the seemingly impossible with a Zilog Z80, enabling a protected mode on the chip for the first time in over four decades. Has he found an elusive undocumented piece of silicon missed by every other researcher? Not quite, but it is a clever hack.

The Z80 has two address spaces, one for memory and the other for I/O. He’s taken the I/O request line and fed it through a flip-flop and some logic to call a hardware interrupt the first time an I/O call is made or when a RST instruction is executed. Coupled with a small piece of memory for register contents, and he’s made a Z80 with a fully-functional protected mode, for the cost of a few logic chips. It’s explained in the video below the break, and we hope you agree that it’s rather elegant given the resources in hand. It’s too late for the commercial 8-bit machines of the past, but it would be interesting to see what today’s retrocomputer designers make of it.

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DIY Heat-Set Insert Press Says Complicated = Comfort

Heat-set inserts are a great way to embed mechanically-strong, threaded parts into a 3D print. For installation, all that is required is an economical soldering iron; something most of us already have.

The carriage and counterweight use a v-wheel gantry, GT2 belt, and other common hardware.

That’s fine for a handful of occasional inserts, but when a large number need to be inserted reliably and cleanly, something a little more refined is called for. That’s where [virchow]’s threaded insert press design comes in. It adds 3D-printed parts to an aluminum extrusion frame to create a press that smoothly lowers a soldering iron directly up and down, with minimal effort by the user.

The holder for the soldering iron is mounted to a small v-wheel gantry that rides along the vertical extrusion. The gantry features a counterweight to take care of resetting the position of the iron. [Virchow] admits that the design could be considered unnecessarily complicated (hence the “UC” in the name) but on the other hand, there’s nothing like doing a hundred or so inserts to make one appreciate every bit of comfort and stability.

Heat-set inserts aren’t difficult to use, but a little technique goes a long way. Spend a few minutes reading Joshua Vasquez’s guide on the optimal way to use them in 3D-printed parts to make sure yours not only go in straight but end up looking great as well.

ERRF 22: Baby Belt Promises Infinite Z For Under $200

Hackaday has been reporting on belt printers for around a decade now, since MakerBot released (and then quickly pulled) an automated build platform for their very first Cupcake printer. Turns out that not only has the concept been difficult to pull off from a technical perspective, but a murky patent situation made it tricky for anyone who wanted to bring their own versions to market. For a long time they seemed like the fusion reactors of desktop 3D printing — a technology that remains perennially just outside of our grasp.

But finally, things have changed. The software has matured, and there are now several commercial belt printers on the market. The trick now, as it once was for traditional desktop 3D printing, is to bring the costs down. Enter the Baby Belt, created by [Rob Mink]. This open-source belt printer relies on light-duty components and a largely 3D printed structure to get the price point down, though some will find its diminutive dimensions a bit too limiting…even if one of its axes is technically infinite.

If you’ve already got a printer and filament to burn, [Rob] is selling the part kit for just $130 USD. But even if you opt for the full ready-to-build kit, it will only set you back $180. Considering even the cheapest belt printers on the market now have a sticker price of more than $500, that’s an impressive accomplishment.

Of course, it’s hard to compare the Baby Belt with anything else on the market. For one thing, save for a few metal rods, its frame is made almost entirely from 3D-printed parts. Rather than the NEMA 17 stepper motors that are standard on even the cheapest of traditional desktop 3D printers, this little fellow is running on the dinky 28BYJ-48 steppers that you’d expect to find in a cheap toy. Then again, considering the printer only offers 85 x 86 mm in the X and Y axis, the structure and motors don’t exactly need to be top of the line.

What really sets this machine apart is the belt — while we’ve seen other makers go all out with their belt material, [Rob] has come up with an impressively low-tech solution. It’s a simple stack-up of construction paper, carpet tape, and fabric that you could probably put together with what you’ve got laying around the house right now.

Between that outer cloth layer and the printed frame, the Baby Belt offers a lot of room for customization, something which was on clear display at the 2022 East Coast RepRap Festival. The machines dotted several tables on the show floor, and you could tell their builders had a lot of fun making each one their own

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Building A Local Network With LoRaWAN

At its core, the Internet is really just a bunch of computers networked together. There’s no reason that there can’t be other separate networks of computers, or that we all have to tie every computer we have to The One Internet To Rule Them All. In fact, for a lot of embedded systems, it doesn’t make much sense to give them a full network stack and Cat6e Ethernet just to report a few details about themselves. Enter LoRaWAN, a wireless LAN that uses extremely low power for Internet-of-Things devices, and an implementation of one of these networks in an urban environment.

The core of the build is the LoRaWAN gateway which sits at the top of a tall building to maximize the wireless range of all of the other devices. It’s running ChirpStack on the software side and uses a Kerlink Wigrid station to broadcast. The reported range is a little over 9 km with this setup. Other gateways can also be added, and the individual LoRa modules can report to any available gateway. From there, the gateways all communicate back to the central server and the information can be sent out to the wider network, Internet or otherwise.

The project’s creator [mihai.cuciuc] notes that this sort of solution might not be best for everyone. There are other wide area networks available, but using LoRaWAN like this would be likely to scale better as more and more devices are added to the network. For some other ways that LoRa can be used to great effect, take a look at this project which builds an off-grid communications network with it.