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Ayer — 9 Septiembre 2024Salida Principal

Reinforcing Plastic Polymers With Cellulose and Other Natural Fibers

Por: Maya Posch
9 Septiembre 2024 at 14:00

While plastics are very useful on their own, they can be much stronger when reinforced and mixed with a range of fibers. Not surprisingly, this includes the thermoplastic polymers which are commonly used with FDM 3D printing, such as polylactic acid (PLA) and polyamide (PA, also known as nylon). Although the most well-known fibers used for this purpose are probably glass fiber (GF) and carbon fiber (CF), these come with a range of issues, including their high abrasiveness when printing and potential carcinogenic properties in the case of carbon fiber.

So what other reinforcing fiber options are there? As it turns out, cellulose is one of these, along with basalt. The former has received a lot of attention currently, as the addition of cellulose and similar elements to thermopolymers such as PLA can create so-called biocomposites that create plastics without the brittleness of PLA, while also being made fully out of plant-based materials.

Regardless of the chosen composite, the goal is to enhance the properties of the base polymer matrix with the reinforcement material. Is cellulose the best material here?

Cellulose Nanofibers

Plastic objects created by fused deposition modeling (FDM) 3D printing are quite different from their injection-molding counterparts. In the case of FDM objects, the relatively poor layer adhesion and presence of voids means that 3D-printed PLA parts only have a fraction of the strength of the molded part, while also affecting the way that any fiber reinforcement can be integrated into the plastic. This latter aspect can also be observed with the commonly sold CF-containing FDM filaments, where small fragments of CF are used rather than long strands.

According to a study by Tushar Ambone et al. (2020) as published (PDF) in Polymer Engineering and Science, FDM-printed PLA has a 49% lower tensile strength and 41% lower modulus compared to compression molded PLA samples. The addition of a small amount of sisal-based cellulose nanofiber (CNF) at 1% by weight to the PLA subsequently improved these parameters by 84% and 63% respectively, with X-ray microtomography showing a reduction in voids compared to the plain PLA. Here the addition of CNF appears to significantly improve the crystallization of the PLA with corresponding improvement in its properties.

Fibers Everywhere

Incidentally a related study by Chuanchom Aumnate et al. (2021) as published in Cellulose used locally (India) sourced kenaf cellulose fibers to reinforce PLA, coming to similar results. This meshes well with the findings by  Usha Kiran Sanivada et al. (2020) as published in Polymers, who mixed flax and jute fibers into PLA. Although since they used fairly long fibers in compression and injection molded samples a direct comparison with the FDM results in the Aumnate et al. study is somewhat complicated.

Meanwhile the use of basalt fibers (BF) is already quite well-established alongside glass fibers (GF) in insulation, where it replaced asbestos due to the latter’s rather unpleasant reputation. BF has some advantages over GF in composite materials, as per e.g. Li Yan et al. (2020) including better chemical stability and lower moisture absorption rates. As basalt is primarily composed of silicate, this does raise the specter of it being another potential cause of silicosis and related health risks.

With the primary health risk of mineral fibers like asbestos coming from the jagged, respirable fragments that these can create when damaged in some way, this is probably a very pertinent issue to consider before putting certain fibers quite literally everywhere.

A 2018 review by Seung-Hyun Park in Saf Health Work titled “Types and Health Hazards of Fibrous Materials Used as Asbestos Substitutes” provides a good overview of the relative risks of a range of asbestos-replacements, including BF (mineral wool) and cellulose. Here mineral wool fibers got rated as IARC Group 3 (insufficient evidence of carcinogenicity) except for the more biopersistent types (Group 2B, possibly carcinogenic), while cellulose is considered to be completely safe.

Finally, related to cellulose, there is also ongoing research on using lignin (present in plants next to cellulose as cell reinforcement) to improve the properties of PLA in combination with cellulose. An example is found in a 2021 study by Diana Gregor-Svetec et al. as published in Polymers. PLA composites created with lignin and surface-modified nanofibrillated (nanofiber) cellulose (NFC). A 2023 study by Sofia P. Makri et al. (also in Polymers) examined methods to improve the dispersion of the lignin nanoparticles. The benefit of lignin in a PLA/NFC composite appears to be in UV stabilization most of all, which should make objects FDM printed using this material last significantly longer when placed outside.

End Of Life

Another major question with plastic polymers is what happens with them once they inevitably end up discarded in the environment. There should be little doubt about what happens with cellulose and lignin in this case, as every day many tons of cellulose and lignin are happily devoured by countless microorganisms around the globe. This means that the only consideration for cellulose-reinforced plastics in an end-of-life scenario is that of the biodegradability of PLA and other base polymers one might use for the polymer composite.

Today, many PLA products end up discarded in landfills or polluting the environment, where PLA’s biodegradability is consistently shown to be poor, similar to other plastics, as it requires an industrial composting process involving microbial and hydrolytic treatments. Although incinerating PLA is not a terrible option due to its chemical composition, it is perhaps an ironic thought that the PLA in cellulose-reinforced PLA might actually be the most durable component in such a composite.

That said, if PLA is properly recycled or composted, it seems to pose few issues compared to other plastics, and any cellulose components would likely not interfere with the process, unlike CF-reinforced PLA, where incinerating it is probably the easiest option.

Do you print with hybrid or fiber-mixed plastics yet?

Printed in Space: 3D-Printed Metal Parts Shown Off After Returning From the ISS

Por: Maya Posch
9 Septiembre 2024 at 02:00

The European Space Agency (ESA) is showing 3D-printed metal parts made onboard the International Space Station using a printer and materials the agency sent earlier this year.  While 3D printing onboard the ISS is nothing new, the printing of metal parts in space is an important advancement. The agency’s goals are to be able to produce more tools and spares in situ rather than having to rely on resupply missions. An ambitious idea being pitched is to use captured space debris as input as well, which would further decrease the ISS’s dependence on Earth and expensive cargo runs from the bottom of the gravity well.

The metal 3D printer in operation during testing on Earth prior to being installed on the ISS. (Credit: ESA)
The metal 3D printer in operation during testing on Earth prior to being installed on the ISS. (Credit: ESA)

The 180 kg 3D printer lives in the European Drawer Rack Mark II inside ESA’s Columbus module. Controllers on Earth managed the printing process after installation. The printer ran for about four hours a day, with each layer inspected before continuing. This means the printing process took days, but running the machine continuously would, of course, cut printing time significantly.

The printer uses stainless steel wire that is fed to the printing location, where a laser melts it. As the pool of molten metal moves away from the laser-heated spot, it solidifies like plastic does in a regular FDM printer. Of course, with the melting point of stainless steel being around 1400 °C, it runs a lot hotter and thus requires that the printer to be inside a completely sealed box, with the atmosphere inside vented into space and replaced with nitrogen prior to starting the printing process. The presence of oxygen would totally ruin the print.

We badly want a practical metal printer for home use, but, so far, they remain out of reach. When you do get them, you might consider that there are different design rules for metal-printed parts.

AnteayerSalida Principal

Rendering Skin Transparent Using the Food Dye Tartrazine

Por: Maya Posch
7 Septiembre 2024 at 23:00

Although we generally assume that opacity is the normal look for animals like us humans, this factoid is only correct for as long as you maintain the dissimilar optical refraction indices of skin and the more aqueous underlying structures. What if you could change the refraction index of skin? If you could prevent the normal scattering at the interface, you could reveal the structures underneath, effectively rendering skin transparent. [Zihao Uo] and others demonstrate this in a paper published in Science.

The substance they used was the common food dye known as tartrazine, which also goes by the names of Yellow 5 and E102 when it is used in food (like Doritos), cosmetics, and drugs. By rubbing the tartrazine into the skin of mice, the researchers were able to observe underlying blood vessels and muscles. Simulations predicted that the dye would change the refraction index mismatch between lipids and water which normally causes the light scattering that creates the skin’s opaque appearance. With the dye rubbed into the skin, the effect worked to a depth of about 3 mm, which makes it useful for some research and possible medical applications, but not quite at the ‘jellyfish-transparency’ levels that some seem to have imagined at the news.

Researchers and medical personnel have long wished for this kind of in vivo tissue transparency. A 2019 review article by [Mikhail Inyushin] and colleagues in Molecules provides an overview of the many possible ways, both genetic and chemical, that you might see through skin. Tartrazine has a significant advantage: it is generally considered to be a harmless food dye. In addition, reversing the effect is as simple as washing the dye off.

Naturally, human skin will be trickier than that of mice due to the varying presence of melanin. So it will take more work to use this technique on people, but there are many mice and other common lab test critters who are breathing a deep sigh of relief as the scalpel can be put away for some types of studies.

For now, better to stick with MRI. And fair warning: there’s no need to rush out to rub Doritos on your PCB — it doesn’t work.

Getting Started With Polypropylene (PP) 3D Printing

Por: Maya Posch
7 Septiembre 2024 at 05:00

Polypropylene (PP) is a thermoplastic that has a number of properties that sets it apart from other thermoplastics which see common use with 3D printing, including PLA, ABS and nylon (PA). Much like ABS (and the similar ASA), it is a pretty touchy material to print, especially on FDM printers. Over at the [All3DP] site [Nick Loth] provides a quick start guide for those who are interested in using PP with 3D printing, whether FDM, SLS or others.

A nice aspect of printing with PP is that it requires similar temperatures for the extruder (205 – 275 °C) and print  bed (80 – 100 °C) as other common FDM filaments. As long as airflow can be controlled in the (enclosed) printer, issues with warping and cracking as the extruded filament cools should not occur. Unlike ABS and ASA which also require an enclosed, temperature-controlled printing space, PP has an advantage that printing with it does not produce carcinogenic fumes (styrene, acrylonitrile, etc.), but it does have the issue of absolutely not wanting to adhere to anything that is not PP. This is where the article provides some tips, such as the use of PP-based adhesive tape on the print bed, or the use of PP-based print plates.

As far as PP longevity and recyclability goes, it compares favorably with ABS and PA, meaning it’s quite resilient and stable, though susceptible to degradation from UV exposure without stabilizers. Recycling PP is fairly easy, though much like with polymers like PLA, the economics and logistics of recycling remain a challenge.

Bluetooth Version 6.0 Core Specification Released

Por: Maya Posch
7 Septiembre 2024 at 02:00

The Bluetooth SIG recently released the core specification for version 6.0 of Bluetooth. Compared to 5.x, it contains a number of changes and some new features, the most interesting probably being Channel Sounding. This builds upon existing features found in Bluetooth 5.x to determine the angle to, and direction of another device using Angle of Arrival (AoA) and Angle of Departure (AoD), but uses a new approach to much more precisely determine these parameters. as defined in the Technical Overview document for this feature.

In addition to this feature, there are also new ways to filter advertising packets, to reduce the number of packets to sift through (Decision-Based Advertising Filtering) and to filter out duplicate packets (Monitoring Advertisers). On a fundamental level, the Isochronous Adaptation Layer (ISOAL) received a new framing mode to reduce latency and increase reliability, alongside frame spacing now being negotiable and additional ways to exchange link layer information between devices.

As with any Bluetooth update, it will take a while before chipsets supporting it become widely available, and for the new features to be supported, but it gives a glimpse of what we can likely expect from Bluetooth-enabled devices in the future.

The Worsening Raspberry Pi RP2350 E9 Erratum Situation

Por: Maya Posch
4 Septiembre 2024 at 20:00

There’s currently a significant amount of confusion around the full extent of the GPIO hardware issue in the Raspberry Pi RP2350 microcontroller, with [Ian] over at [Dangerous Prototypes] of Bus Pirate fame mentioning that deliveries of the RP2350-based Bus Pirate 5XL and 6 have been put on hold while the issue is further being investigated. Recorded in the MCU’s datasheet as erratum RP2350-E9, it was originally reported as only being related to the use of internal pull-downs, but [Ian] has since demonstrated in the primary issue ticket on GitHub that the same soft latching behavior on GPIO pins occurs also without pull-downs enabled.

Ian from Dangerous Prototypes demonstrating the RP2350-E9 issue in a Bus Pirate prototype without pull-ups.
Ian from Dangerous Prototypes demonstrating the RP2350-E9 issue in a Bus Pirate prototype without pull-ups.

When we first reported on this hardware bug in the RP2350’s A2 (and likely preceding) stepping there was still a lot of confusion about what this issue meant, but so far we have seen the Bus Pirate delay and projects like [Agustín Gimenez Bernad]’s LogicAnalyzer have opted for taking the RP2350 port out back. There are also indications that the ADC and PIO peripherals are affected by this issue, with workarounds only partially able to circumvent the hardware issue.

In the case of the Bus Pirate a potential workaround is the addition of 4.7 kOhm external pull-downs, but at the cost of 0.7 mA continuous load on the GPIO when pulled high and part of that when pulled low. It’s an ugly hack, but at the very least it might save existing boards. It also shows how serious a bug this is.

Meanwhile there are lively discussions about the issue on the Raspberry Pi forums, both on the E9 erratum as well as the question of when there will be a new stepping. The official statement by Raspberry Pi is still that ‘they are investigating’. Presumably there will be a Bx stepping at some point, but for now it is clear that the RP2350’s A2 stepping is probably best avoided.

A Windows Control Panel Retrospective Amidst a Concerning UX Shift

Por: Maya Posch
3 Septiembre 2024 at 14:00

Once the nerve center of Windows operating systems, the Control Panel and its multitude of applets has its roots in the earliest versions of Windows. From here users could use these configuration applets to control and adjust just about anything in a friendly graphical environment. Despite the lack of any significant criticism from users and with many generations having grown up with its familiar dialogs, it has over the past years been gradually phased out by the monolithic Universal Windows Platform (UWP) based Settings app.

Whereas the Windows control panel features an overview of the various applets – each of which uses Win32 GUI elements like tabs to organize settings – the Settings app is more Web-like, with lots of touch-friendly whitespace, a single navigable menu, kilometers of settings to scroll through and absolutely no way to keep more than one view open at the same time.

Unsurprisingly, this change has not been met with a lot of enthusiasm by the average Windows user, and with Microsoft now officially recommending users migrate over to the Settings app, it seems that before long we may have to say farewell to what used to be an intrinsic part of the Windows operating system since its first iterations. Yet bizarrely, much of the Control Panel functionality doesn’t exist yet in the Settings app, and it remain an open question how much of it can be translated into the Settings app user experience (UX) paradigm at all.

Considering how unusual this kind of control panel used to be beyond quaint touch-centric platforms like Android and iOS, what is Microsoft’s goal here? Have discovered a UX secret that has eluded every other OS developer?

A Simple Concept

The Windows 3.1 Control Panel (1992). (Source: ToastyTech.com)
The Windows 3.1 Control Panel (1992). (Source: ToastyTech.com)

Settings which a user may want to tweak on their computer system range from hardware devices and networks to the display resolution and wallpaper, so it makes sense to put all of these configuration options within an easy to reach and use location. Generally this has meant something akin to a folder containing various clickable icons and accompanying text which together make clear what settings can be configured by opening it. In addition, the same setting dialogs can be accessed using context-sensitive menus, such as when right-clicking on the desktop.

The Windows 98 Control Panel. (Source: ToastyTech.com)
The Windows 98 Control Panel. (Source: ToastyTech.com)

It’s little wonder that for the longest time operating systems have settled for this approach, as it is intuitive, and individual items can have stylized icons that make it even more obvious what settings can be configured by clicking on it, such a keyboard, a mouse, a display, etc. As graphical fidelity increased, so did the styling of these icons, with MacOS, Windows, BeOS and the various desktop environments for OSs like the Linuxes and BSDs all developing their own highly skeuomorphic styles to make their UIs more intuitive and also more pleasant to look at. A good overview of the Windows Control Panel evolution can be found over at the Version Museum website.

The Windows XP Control Panel in 'Classic' view. (2001) (Source: suffieldacademy.org)
The Windows XP Control Panel in ‘Classic’ view. (2001) (Source: suffieldacademy.org)

Coming from the still somewhat subdued style of Windows XP after years of Windows 9x and Windows NT/2000, Windows Vista and Windows 7 cranked this style up to eleven with the Windows Aero design language. This meant glass, color, translucency, depth and high-fidelity icons that made the function of the Control Panel’s individual entries more obvious than ever, creating a masterpiece that would be very hard to beat. The user was also given two different ways to view the Control Panel: the simplified category-based view, or the ‘classic’ view with all icons (and folders for e.g. Administrative Tools) visible in one view.

Windows 7 Control Panel (2009) in category view. (Source: techrepublic.com)
Windows 7 Control Panel (2009) in category view. (Source: techrepublic.com)

Meanwhile Apple did much the same thing, leaning heavily into their unique design language not only for its desktop, but ultimately also for its mobile offerings. Everything was pseudo-3D, with vivid colors adorning detailed renderings of various physical items and so on, creating a true feast for the eyes when taking in these lush UIs, with efficient access to settings via clearly marked tabs and similar UI elements.

The Mac OS X Panther System Preferences in 2003. (Source: Gadget Unity TV)
The Mac OS X Panther System Preferences in 2003. (Source: Gadget Unity TV)

This way of organizing system settings was effectively replicated across a multitude of environments, with operating systems like Haiku (based on BeOS) and ReactOS (re-implementing Windows) retaining those classical elements of the original. A truly cross-platform, mostly intuitive experience was created, and Bliss truly came to the computing world.

Naturally, something so good had no right to keep existing, ergo it had to go.

The World Is Flat

The first to make the big change was Microsoft, with the release of Windows 8 and its Metro design language. This new visual style relied on simple shapes, with little to no adornments or distractions (i.e. more than a single color). Initially Microsoft also reckoned that Windows users wanted every window to be full-screen, and that hot edges and sides rather than a task bar and start menu was the way to go, as every single system running Windows 8 would obviously have a touch screen. Fortunately they did backtrack on this, but their attempt to redesign the Control Panel into something more Metro-like with the Settings app did persist, like an odd growth somewhere on a body part.

Windows 8's PC Settings app (2012). (Source: softpedia.com)
Windows 8’s PC Settings app (2012). (Source: softpedia.com)

Although the Control Panel remained in Windows 8 as well, the course had been set. Over time this small lump developed into the Settings app in Windows 10, by which time Metro had been renamed into the Microsoft Design Language (MDL), which got a recent tweak in what is now called the Fluent Design Language (FDL) for Windows 11.

Central to this is the removal of almost all colors, the use of text labels over icons where possible (though simple monochrome icons are okay) and only rectangles with no decorations. This also meant no folder-centric model for settings but rather all the items put into a text-based menu on the left-hand side and an endless scroll-of-doom on the right side containing sparsely distributed settings.

This led to the absolutely beautifully dystopian Settings app as it exists in Windows 10:

The Settings app in Windows 10 back in ~2015. Hope you don't like colors.
The Settings app in Windows 10 back in ~2015. Hope you don’t like colors.

All of this came as skeuomorphic designs were suddenly considered ‘passé’, and the new hotness was so-called Flat Design. Google’s Material Design as developed in 2014 is another good example of this, with the characteristic ‘flat UI elements adrift in a void’ aesthetic that has now been adopted by Microsoft, and a few years ago by Apple as well starting in 2022 with MacOS Ventura’s System Settings (replacing System Preferences).

Monterey’s General system preferences (left) are different from Ventura’s General system settings (right). (Credit: MacWorld)
Monterey’s General system preferences (left) are different from Ventura’s General system settings (right). (Credit: MacWorld)

Rather than a tabbed interface to provide a clear overview, everything is now a blind hierarchy of menu items to scroll through and activate to access sub-, sub-sub-, and sub-sub-sub- items, and inevitably realize a few times that you’re in the wrong section. But rather than being able to click that other, correct tab, you now get to navigate back multiple views, one click at a time.

It isn’t just Windows and Apple either, but many of the big desktop environments like Gnome have also moved to this Flat Design Language. While various reasons have been provided for these changes, it’s undeniable that FDL makes a UI less intuitive (because there’s less useful visual information) and makes for a worse user experience (UX) with worse ergonomics as a result (because of the extra scrolling and clicking). This is especially obvious in the ‘independent applets’ versus ‘monolithic settings app’ comparison.

One-Track Mind

Imagine that you’re trying out a couple new wallpapers in Windows while keeping an eye on Windows Update’s latest shenanigans. You then need to quickly adjust the default audio device or another small adjustment unrelated to any of these other tasks. If you are using Windows 7 or earlier with the Control Panel applets, this is normal behavior and exceedingly common especially during hardware troubleshooting sessions.

If you’re using the Settings app, this is impossible, as only view can be active at a given time. You think you’re smart and right-click the desktop for ‘Personalize desktop’ so that the other Settings view stays intact? This is not how it works, as the Settings app is monolithic and now shifts to the newly selected view. Currently this is not too noticeable yet as many applets still exist in Windows 10 and 11, but as more and more of these are assimilated into the Settings app, such events will become more and more common.

It would seem that after decades of UI and UX evolution, we have now reached a definite point where UX is only getting worse, arguably around the release of Windows 8. With color banished, anything even remotely pseudo-3D frowned upon and UIs based around touch interfaces, there will soon be no difference between using a desktop PC, tablet or smartphone. Just in the worst way possible, as nobody has ever written about the amazing ergonomics and efficient UX of the latter two devices.

Perhaps our only hope may lie with the OSes and desktop environments that keep things real and stick to decades of proven UX design rather than give into Fad Driven Development.

Rest in peace, Windows Control Panel. We hope to see you again soon in ReactOS.

New 2 GB Raspberry Pi 5 Has Smaller Die and 30% Lower Idle Power Usage

Por: Maya Posch
30 Agosto 2024 at 11:00

Recently Raspberry Pi released the 2GB version of the Raspberry Pi 5 with a new BCM2712 SoC featuring the D0 stepping. As expected, [Jeff Geerling] got his mitts on one of these boards and ran it through its paces, with positive results. Well, mostly positive results — as the Geekbench test took offence to the mere 2 GB of RAM on the board and consistently ran out of memory by the multi-core Photo Filter test, as feared when we originally reported on this new SBC. Although using swap is an option, this would not have made for a very realistic SoC benchmark, ergo [Jeff] resorted to using sysbench instead.

Naturally some overclocking was also performed, to truly push the SoC to its limits. This boosted the clock speed from 2.4 GHz all the way up to 3.5 GHz with the sysbench score increasing from 4155 to 6068. At 3.6 GHz the system wouldn’t boot any more, but [Jeff] figured that delidding the SoC could enable even faster speeds. This procedure also enabled taking a look at the bare D0 stepping die, revealing it to be 32.5% smaller than the previous C1 stepping on presumably the same 16 nm process.

Although 3.5 GHz turns out to be a hard limit for now, the power usage was interesting with idle power being 0.9 watts lower (at 2.4 W) for the D0 stepping and the power and temperatures under load also looked better than the C1 stepping. Even when taking the power savings of half the RAM versus the 4 GB version into account, the D0 stepping seems significantly more optimized. The main question now is when we can expect to see it appear on the 4 and 8 GB versions of the SBC, though the answer there is likely ‘when current C1 stocks run out’.

IBM’s Latest Quantum Supercomputer Idea: the Hybrid Classical-Quantum System

Por: Maya Posch
29 Agosto 2024 at 02:00

Although quantum processors exist today, they are still a long way off from becoming practical replacements for classical computers. This is due to many practical considerations, not the least of which are factors such as the need for cryogenic cooling and external noise affecting the system necessitating a level of error-correction which does not exist yet. To somewhat work around these limitations, IBM has now pitched the idea of a hybrid quantum-classical computer (marketed as ‘quantum-centric supercomputing’), which as the name suggests combines the strengths of both to create a classical system with what is effectively a quantum co-processor.

IBM readily admits that nobody has yet demonstrated quantum advantage, i.e. that a quantum computer is actually better at tasks than a classical computer, but they figure that by aiming for quantum utility (i.e. co-processor level), it could conceivably accelerate certain tasks for a classical computer much like how a graphics processing unit (GPU) is used to offload everything from rendering graphics to massively parallel computing tasks courtesy of its beefy vector processing capacity. IBM’s System Two is purported to demonstrate this when it releases.

What the outcome here will be is hard to say, as the referenced 2023 quantum utility demonstration paper involving an Ising model was repeatedly destroyed by classical computers and even trolled by a Commodore 64-based version. Thus, at the very least IBM’s new quantum utility focus ought to keep providing us with more popcorn moments like those, and maybe a usable quantum system will roll out by the 2030s if IBM’s projected timeline holds up.

Hardware Bug in Raspberry Pi’s RP2350 Causes Faulty Pull-Down Behavior

Por: Maya Posch
28 Agosto 2024 at 20:00
Erratum RP2350-E9 in the RP2350 datasheet, detailing the issue.
Erratum RP2350-E9 in the RP2350 datasheet, detailing the issue.

The newly released RP2350 microcontroller has a confirmed new bug in the current A2 stepping, affecting GPIO pull-down behavior. Listed in the Raspberry Pi RP2350 datasheet as errata RP2350-E9, it involves a situation where a GPIO pin is configured as a pull-down with input buffer enabled. After this pin is then driven to Vdd (e.g. 3.3V) and then disconnected, it will stay at around 2.1 – 2.2 V for a Vdd of 3.3V. This issue was discovered by [Ian Lesnet]  of [Dangerous Prototypes] while working on an early hardware design using this MCU.

The suggested workaround by Raspberry Pi is to enable the input buffer before a read, and disable it again immediately afterwards. Naturally, this is far from ideal workaround, and the solution that [Ian] picked was to add external pull-down resistors. Although this negates the benefits of internal pull-down resistors, it does fix the issue, albeit with a slightly increased board size and BOM part count.

As for the cause of the issue, Raspberry Pi engineer [Luke Wren] puts the blame on an external IP block vendor. With hindsight perhaps running some GPIO validation tests involving pull-up and pull-down configurations with and without input buffer set could have been useful, but we’re guessing they may be performed on future Pi chips. Maybe treating the RP2350 A0 stepping as an ‘engineering sample’ is a good idea for the time being, with A3 (or B0) being the one you may want to use in actual production.

In some ways this feels like déjà vu, as the Raspberry Pi 4 and previous SBCs had their own share of issues that perhaps might have been caught before production.

(Note: original text listed A0 as current stepping, which is incorrect. Text has been updated correspondingly)

DEC’s LAN Bridge 100: The Invention of the Network Bridge

Por: Maya Posch
28 Agosto 2024 at 02:00

DEC’s LAN Bridge 100 was a major milestone in the history of Ethernet which made it a viable option for the ever-growing LANs of yesteryear and today. Its history is also the topic of a recent video by [The Serial Port], in which [Mark] covers the development history of this device. We previously covered the LANBridge 100 Ethernet bridge and what it meant as Ethernet saw itself forced to scale from a shared medium (ether) to a star topology featuring network bridges and switches.

Featured in the video is also an interview with [John Reed], a field service network technician who worked at DEC from 1980 to 1998. He demonstrates what the world was like with early Ethernet, with thicknet coax (10BASE5) requiring a rather enjoyable way to crimp on connectors. Even with the relatively sluggish 10 Mbit of thicknet Ethernet, adding an Ethernet store and forward bridge in between two of these networks required significant amounts of processing power due to the sheer number of packets, but the beefy Motorola 68k CPU was up to the task.

To prevent issues with loops in the network, the spanning tree algorithm was developed and implemented, forming the foundations of the modern-day Ethernet LANs, as demonstrated by the basic LAN Bridge 100 unit that [Mark] fires up and which works fine in a modern-day LAN after its start-up procedure. Even if today’s Ethernet bridges and switches got smarter and more powerful, it all started with that first LAN Bridge.

3D Printed Electronics Breadboard

Por: Maya Posch
25 Agosto 2024 at 20:00
The printed breadboard cover, seen from the bottom. (Credit: CHEP, YouTube)
The printed breadboard cover as seen from the bottom. (Credit: CHEP, YouTube)

Does it make sense to make your own breadboards rather than purchasing off the shelf ones? As [Chuck Hellebuyck] notes in a recent video on DIY, 3D-printed breadboards, there’s a certain charm to making a breadboard exactly the size you need, which is hard to argue with. The inspiration came after seeing the metal breadboard spring clips on sale by [Kevin Santo Cappuccio], who also has a 3D printable breadboard shell project that they fit into. This means that you can take the CAD model (STEP file) and modify it to fit your specifications before printing it, which is what [Chuck] attempts in the video.

The models were exported from TinkerCAD to Bambu Lab Studio for printing on a Bambu Lab A1 Mini FDM printer. After a failed first print (which the A1 Mini, to its credit, did detect), a model was printed on a Creality K1 Max instead. Ultimately [Chuck] traced this back to the Bambu Lab Studio slicer failing to add the inner grid to the first layer, which the Creality slicer did add, caused by the ‘wall generator’ setting in the Bambu Lab slicer being set to ‘Classic’ rather than ‘Arachne,’ which can vary line width.

After this, the models printed fine and easily fit onto the spring clips that [Chuck] had soldered down on some prototyping board. A nice feature of these spring clips is that they have a bit of space underneath them where an SMD LED can fit, enabling functional (or just fancy) lighting effects when using a custom PCB underneath the contraption. As for whether it’s worth it depends on your needs. As [Chuck] demonstrates, it can be pretty convenient for a small breadboard on an add-on card (with or without custom lighting) like this, but it’s unlikely to replace generic breadboards for quick prototyping. We can, however, imagine a custom breadboard with mounting points for things like binding posts, switches, or potentiometers.

If we had that kind of custom breadboard, we wouldn’t need these. People were making custom breadboards back in 1974, but they didn’t look like these.

Lunar Landing Lunacy: Charles Duke Confronted With Reality-Deniers

Por: Maya Posch
25 Agosto 2024 at 05:00
Charles Duke during his interview with Jack Gordon. (Credit: Jack Gordon, YouTube)
Lunar Module pilot Charles Duke saluting the US flag during Apollo 16. (Credit: NASA)
Lunar Module pilot Charles Duke saluting the US flag during Apollo 16. (Credit: NASA)

Imagine: you spent years training for a sojourn to the Moon, flew there on top of a Saturn V rocket as part of Apollo 16, to ultimately land on the lunar surface. You then spend the next few days on the surface, walking and skipping across the lunar regolith while setting up experiments and exploring per your mission assignments. Then, you pack everything up and blast off from the lunar surface to the orbiting command module before returning to Earth and a hero’s welcome. Then, decades later, you are told to your face that none of that ever happened. That’s the topic of a recent interview which [Jack Gordon] recently did with astronaut [Charles Duke].

None of these ‘arguments’ provided by the reality-denying crowd should be too shocking or feel new, as they range from the amount of fuel required to travel to the moon (solved by orbital mechanics) to the impossibility of lighting on the Moon (covered by everyone and their dog, including the Mythbusters in 2008).

Of course, these days, we have lunar orbiters (LRO and others) equipped with powerful cameras zoomed in on the lunar surface, which have photographed the Apollo landing sites with the experiments and footsteps still clearly visible. Like today’s crowd of spherical Earth deniers, skeptics will denounce anything that doesn’t fit their ill-conceived narrative as ‘faked’ for reasons that only exist in their fevered imaginations.

A common objection we’ve heard is that if we went to the moon back then, why haven’t we been back? The reason is obvious: politics. The STS (Shuttle) project sucked up all funding and the USSR collapsed. Only recently has there been a new kind of ‘space race’ in progress with nations like China. That doesn’t keep countless individuals from dreaming up lunar landing conspiracy theories to file away with their other truth nuggets, such as how microwaved and genetically engineered foods cause cancer, vaccines are another government conspiracy to control the population, and nuclear power plants can explode like nuclear bombs.

Perhaps the best takeaway is that even if we have not found intelligent life outside Earth yet, for at least a few years, intelligent life was the only kind on Earth’s Moon. We wish [Charles Duke] many happy returns, with maybe a casual return to the Moon in the near future as well, to frolic once more on the lunar surface.

Not that there hasn’t been a moon hoax, just not lately. If you want to watch the old Apollo video, it has been improved in recent years.

Meta Cancels Augmented Reality Headset After Apple Vision Pro Falls Flat

Por: Maya Posch
24 Agosto 2024 at 23:00

The history of consumer technology is littered with things that came and went. For whatever reason, consumers never really adopted the tech, and it eventually dies. Some of those concepts seem to persistently hang on, however, such as augmented reality (AR). Most recently, Apple launched its Vision Pro ‘mixed reality’ headset at an absolutely astounding price to a largely negative response and disappointing sale numbers. This impending market flop seems to now have made Meta (née Facebook) reconsider bringing a similar AR device to market.

To most, this news will come as little of a surprise, considering that Microsoft’s AR product (HoloLens) explicitly seeks out (government) niches with substantial budgets, and Google’s smart glasses have crashed and burned despite multiple market attempts. In a consumer market where virtual reality products are already desperately trying not to become another 3D display debacle, it would seem clear that amidst a lot of this sci-fi adjacent ‘cool technology,’ there are a lot of executives and marketing critters who seem to forego the basic question: ‘why would anyone use this?’

In the case of the Apple Vision Pro, the current debate is if augmented reality and spatial computing have any future at all, even as work on a Vision Pro 2 has been suspended. Meanwhile, Meta has decided to keep plugging away on its next VR headset (the predictably named Quest 4), as the VR consumer market so far is relatively healthy for a consumer product with limited mass-consumer appeal but with potential new use cases beyond games.

Comparing AliExpress vs LCSC-Sourced MOSFETs

Por: Maya Posch
24 Agosto 2024 at 20:00
The fake AliExpress-sourced IRFP460 MOSFETs (Credit: Learn Electronics Repair, YouTube)

These days, it’s super-easy to jump onto the World Wide Web to find purported replacement parts using nothing but the part identifier, whether it’s from a reputable source like Digikey or Mouser or from more general digital fleamarkets like eBay and AliExpress. It’s hardly a secret that many of the parts you can buy online via fleamarkets are not genuine. That is, the printed details on the package do not match the actual die inside. After AliExpress-sourced MOSFETs blew in a power supply repair by [Learn Electronics Repair], he first tried to give the MOSFETs the benefit of the doubt. Using an incandescent lightbulb as a current limiter, he analyzed the entire PSU circuit before putting the blame on the MOSFETs (IRFP460) and ordering new ones from LCSC.

Buying from a distributor instead of a marketplace means you can be sure the parts are from the manufacturer. This means that when a part says it is a MOSFET with specific parameters, it almost certainly is. A quick component tester session showed the gate threshold of the LCSC-sourced MOSFETs to be around 3.36V, while that of the AliExpress ‘IRFP460’ parts was a hair above 1.8V, giving a solid clue that whatever is inside the AliExpress-sourced MOSFETs is not what the package says it should be.

Unsurprisingly, after fitting the PSU with the two LCSC-sourced MOSFETs, there was no more magic smoke, and the PSU now works. The lesson here is to be careful buying parts of unknown provenance unless you like magic smoke and chasing weird bugs.

Intuitive Explanation of Arithmetic, Geometric & Harmonic Mean

Por: Maya Posch
24 Agosto 2024 at 08:00

The simple definition of a mean is that of a numeric quantity which represents the center of a collection of numbers. Here the trick lies in defining the exact type of numeric collection, as beyond the arithmetic mean (AM for short, the sum of all values divided by their number) there are many more, with the other two classical Pythagorean means being the geometric mean (GM) and harmonic mean (HM).

The question that many start off with, is what the GM and AM are and why you’d want to use them, which is why [W.D.] wrote a blog post on that topic that they figure should be somewhat intuitive relative to digging through search results, or consulting the Wikipedia entries.

Compared to the AM, the GM uses the product of the values rather than the sum, which makes it a good fit for e.g. changes in a percentage data set. One thing that [W.D] argues for is to use logarithms to grasp the GM, as this makes it more obvious and closer to taking the AM. Finally, the HM is useful for something like the average speed across multiple trips, and is perhaps the easiest to grasp.

Ultimately, the Pythagorean means and their non-Pythagorean brethren are useful for things like data analysis and statistics, where using the right mean can reveal interesting data, much like how other types using something like the median can make a lot more sense. The latter obviously mostly in the hazy field of statistics.

No matter what approach works for you to make these concepts ‘click’, they’re all very useful things to comprehend, as much of every day life revolves around them, including concepts like ‘mean time to failure’ for parts.


Top image: Cycles of sunspots for the last 400 years as an example data set to apply statistical interpretations to. (Credit: Robert A. Rohde, CC BY-SA 3.0)

Second Human Neuralink Brain Implant Recipient Uses It For CAD and Videogaming

Por: Maya Posch
22 Agosto 2024 at 23:00

As Neuralink works towards getting its brain-computer interface technology approved for general use, it now has two human patients who have received the experimental implant. The second patient, [Alex], received the implant in July of 2024 and is said to be doing well, being able to play games like Counter Strike 2 without using his old mouth-operated controller. He’s also creating designs in Fusion 360 to  have them 3D printed.

This positive news comes after the first patient ([Noland Arbaugh]) suffered major issues with his implant, with only 10-15% of the electrodes still working after receiving the implant in January. The issue of electrode threads retracting was apparently a known issue years prior already.

We analyzed Neuralink’s claims back in 2019, when its founder – [Elon Musk] – was painting lofty goals for the implant, including reading and writing of brains, integration with AIs and much more. Since that time Neuralink has been mostly in the news for the many test animals which it euthanized during its test campaign prior to embarking on its first human test subjects.

There also appears a continuing issue with transmitting the noisy data from the electrodes, as it is far more data than can be transmitted wirelessly. To solve this seemingly impossible problem, Neuralink has now turned to the public with its Neuralink Compression Challenge to have someone make a miraculous lossless compression algorithm for it.

With still many challenges ahead, it ought to be clear that it will take many more years before Neuralink’s implant is ready for prime-time, but so far at least it seems to at least make life easier for two human patients.

The First Mass Produced DRAM of the Soviet Union

Por: Maya Posch
22 Agosto 2024 at 02:00
565RU1 die manufactured in 1981.
KE565RU1A (1985) in comparison with the analogue from AMD (1980)
KE565RU1A (1985) in comparison with the analogue from AMD (1980)

Although the benefits of semiconductor technology were undeniable during the second half the 20th century, there was a clear divide between the two sides of the Iron Curtain. Whilst the First World had access to top-of-the-line semiconductor foundries and engineers, the Second World was having to get by with scraps. Unable to keep up with the frantic pace of the USA’s developments in particular, the USSR saw itself reduced to copying Western designs and smuggling in machinery where possible. A good example of this is the USSR’s first mass-produced dynamic RAM (DRAM), the 565RU1, as detailed by [The CPUShack Museum].

While the West’s first commercially mass-produced DRAM began in 1970 with the Intel 1103 (1024 x 1) with its three-transistor design, the 565RU1 was developed in 1975, with engineering samples produced until the autumn of 1977. This DRAM chip featured a three-transistor design, with a 4096 x 1 layout and characteristics reminiscent of Western DRAM ICs like the Ti TMS4060. It was produced at a range of microelectronics enterprises in the USSR. These included Angstrem, Mezon (Moldova), Alpha (Latvia) and Exciton (Moscow).

Of course, by the second half of the 1970s the West had already moved on to single-transistor, more efficient DRAM designs. Although the 565RU1 was never known for being that great, it was nevertheless used throughout the USSR and Second World. One example of this is a 1985 article (page 2) by [V. Ye. Beloshevskiy], the Electronics Department Chief of the Belorussian Railroad Computer Center in which the unreliability of the 565RU1 ICs are described, and ways to add redundancy to the (YeS1035) computing systems.

Top image: 565RU1 die manufactured in 1981.

Atari Announces the Atari 7800+ Nostalgia Console

Por: Maya Posch
21 Agosto 2024 at 20:00

Following the trend of re-releasing every single game console as some kind of modern re-imagining or merely an ARM-SBC-with-emulator slapped into a nice looking enclosure, we now got the announcement from Atari that they will soon be releasing the Atari 7800+.

It’s now up for pre-order for a cool $130 USD or a mega bundle with wired controllers for $170 and shipping by Winter 2024. Rather than it being a cute-but-non-functional facsimile like recent miniature Nintendo and Commodore-themed releases, this particular console is 80% of the size of the original 7800 console, and accepts 2600 and 7800 cartridges, including a range of newly released cartridges.

On the outside you find the cartridge slot, an HDMI video/audio output, a USB-C port (for power) and DE-9 (incorrectly listed as DB-9) controller ports, with wireless controllers also being an option. Inside you find a (2014-vintage) Rockchip RK3128 SoC with a quad core Cortex-A7 that runs presumably some flavor of Linux with the Stella 2600 emulator and ProSystem 7800 emulator. This very likely means that compatibility with 2600 and 7800 titles is the same as for these emulators.

Bundled with the console is a new 7800 cartridge for the game Bentley Bear’s Crystal Quest, and a number of other new games are also up for pre-order at the Atari site. These games are claimed to be compatible with original Atari consoles, which might make it the biggest game release year for the 7800 since its launch, as it only had 59 official games released for it.

Given the backwards compatibility of this new system, you have to wonder how folks who purchased the 2600+ last year are feeling right about now. Then again, the iconic faux-wood trim of the earlier console might be worth the price of admission alone.

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