Linux Fu: Don’t Share Well With Others

December 28, 2021 by 14 Comments

In kindergarten, you learn that you should share. But for computer security, sharing is often a bad thing. The Linux kernel introduced the concept of namespaces starting with version 2.6.24. That’s been a few years ago, but namespaces are not used by many even though the tools exist to manipulate them. Granted, you don’t always need namespaces, but it is one of those things that when you do need it, the capability is priceless. In a nutshell, namespaces let you give a process its own private resources and — more importantly — prevents a process from seeing resources in other namespaces.

Turns out, you use namespaces all the time because every process you run lives in some set of namespaces. I say set, because there are a number of namespaces for different resources. For example, you can set a different network namespace to give a process its own set of networking items including routing tables, firewall rules, and everything else network-related.

So let’s have a look at how Linux doesn’t share names.

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The Pinouts Book Is Here, And It’s Just What You Need

December 28, 2021 by 42 Comments

Updates from the enigmatic [NODE] are unfortunately few and far between these days. In fact his latest post is only the second time we’ve heard from the hacker in 2021. But as we’ve come to expect from his white-on-sorta-black releases, it certainly doesn’t disappoint.

Just in time to ring in whatever holiday you may celebrate, [NODE] has unveiled The Pinouts Book. A project he’s been working on for some time now with colleague [Baptiste], the free PDF download contains over 300 pages of high-contrast hardware diagrams and their respective pinouts. It’s about as straightforward as you can get, beyond the dedication page in the beginning, there’s not a word of fluff in the entire document. This is a work of hacker minimalism at its best, and we’re all about it.

From audio/video connectors all the way to development boards and single-board computers, The Pinouts Book sticks to the same format of a diagram and accompanying chart, making it exceptionally easy to find what you’re looking for. If you need more information than this streamlined layout can provide, each entry includes a link to a dedicated page on the book’s companion website. This will redirect you to supplemental data such as the manufacturer’s website, the part’s full datasheet, etc.

According to [NODE], the original plan for the Creative Commons BY-SA licensed work was to release it as a physical book, but the project ballooned up to such a scale that they realized it would be much easier to navigate and use as a digital document. While we don’t disagree, a physical release would certainly look lovely on our bookshelf. In the meantime, those who want to support the effort financially can purchase shirts emblazoned with diagrams pulled straight from the book’s pages.

We’ve long believed that a large-format electronic paper device would be an ideal gadget for the hacker’s workbench, as it allows for browsing through schematics and datasheets with a minimum of eye strain. Now we can also add a copy of The Pinouts Book to the list of things we’d install on our hacker-friendly e-ink compendium.

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Quantum Atomic Interferometer For Precision Motion Sensing

December 28, 2021 by 16 Comments

The current state of the art of embedded motion sensing is based around micro-electromechanical systems (MEMS) devices. These miracles of microfabrication use tiny silicon structures, configured to detect acceleration and rotational velocity in three dimensions. Accumulate these accelerations and rotations, and you’ve got a device that can find its orientation and track movement without any external waypoints. This is the basis of the technique of dead reckoning.

Why do we care about dead reckoning anyway? Surely GPS and related positioning systems are good enough? Above ground GPS is usually good enough, but underwater and underground this simply won’t work. Even heading indoors has a dramatic effect on the GPS signal strength, so yes, we need another way for some applications.

Right now, the current state of the art in portable sensors are MEMS devices, and you can get them for the cost of a hamburger. But if you want the ultimate in accuracy, you’ll want a quantum atomic interferometer. What that is, and how it will be possible to make one small enough to be useful, is half of the story. But first, let’s talk MEMS.

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Laser doping silicon wafer

Laser Doping His Way To Homemade Silicon Chips

December 28, 2021 by 8 Comments

It’s a pity that more electronics enthusiasts haven’t taken the hobby to its ultimate level: making your own semiconductors. There are plenty of good reasons for that: chief among them is the huge expense involved in obtaining the necessary equipment. But for the sufficiently clever, there are ways around that.

[Zachary Tong] is dipping his toes into the DIY semiconductor world, and further to the goal of keeping costs to a hobbyist scale, is experimenting with laser doping of silicon. Doping is the process of adding impurities to silicon wafers in a controlled manner to alter the electrical properties of the semiconductor. [Zach]’s doping method is a more localized version of the simple thermal diffusion method, which drives a dopant like phosphorus into silicon using high temperatures, but instead of using a tube furnace, he’s using a fiber laser.

The video below shows his two-step process, which first blasts the silicon oxide layer off the wafer before doping with the laser shining through a bath of phosphoric acid. The process is admittedly fussy, and the results were mixed at best. [Zach]’s testing seems to suggest that some doping occurred, and it even looks like he managed to make something reasonably diode-like using the method.

Although the jury is still out on [Zach]’s method, we thought the effort was the important bit here. Granted, not everyone has a fiber laser kicking around to replicate his results, but it’s always good to see progress in the DIY semiconductor field. Here’s hoping [Zach]’s work, along with the stuff that [Sam Zeloof] is doing, kicks off a spate of garage semiconductor fabs.

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Turing Ring Is Compact

December 28, 2021 by 2 Comments

One of the problems with a classic Turing machine is the tape must be infinitely long. [Mark’s] Turing Ring still doesn’t have an infinite tape, but it does make it circular to save space. That along with a very clever and capable UI makes this one of the most usable Turing machines we’ve seen. You can see a demo in the video below.

The device uses an Arduino Nano, a Neopixel ring, an encoder, and a laser-cut enclosure that looks great. The minimal UI has several modes and the video below takes you through all of them.

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Custom Christmas Light Controller Blocks Blinks

December 27, 2021 by 8 Comments

Finding that his recently purchased LED Christmas lights defaulted to an annoying blinking pattern that took a ridiculous seven button presses to disable each time they were powered up, [Matthew Millman] decided to build a new power supply that keeps things nice and simple. In his words, the goal was to enable “all lights on, no blinking or patterns of any sort”.

Connecting the existing power supply to his oscilloscope, [Matthew] found the stock “steady on” setting was a 72 VAC peak-to-peak square wave at about 500 Hz. To recreate this, he essentially needed to find a 36 VDC power supply and swap the polarity back and forth at the same frequency. In the end the closest thing he could find in the parts bin was a HP printer power supply that put out 30 volts, so the lights aren’t quite as bright as they were before, but at least they aren’t blinking.

To turn that into a pair of AC square waves, the power supply is connected to a common L298 H-Bridge module. You might expect a microcontroller to show up at this point, but [Matthew] went old school, and created his two alternating 500 Hz square waves with a 555 timer and a 74HC74D dual flip-flop.

Unfortunately, he didn’t have the time to get a custom PCB made before Santa’s big night. Though as he points out, since legitimate L298s are backordered well into next year anyway, having the board in hand wouldn’t have helped much. The end result is that the circuit has to live on a breadboard for the current holiday season, but hopefully around this time next year we’ll get a chance to see the final product.

Voice Command Made Mostly Easy

December 27, 2021 by 19 Comments

Speech commands are all the rage on everything from digital assistants to cars. Adding it to your own projects is a lot of work, right? Maybe not. [Electronoobs] shows a speech board that lets you easily integrate 255 voice commands via serial communications with a host computer. You can see the review in the video below.

He had actually used a similar board before, but that version was a few years ago, and the new module has, of course, many new features. As of version 3.1, the board can handle 255 commands in a more flexible way than the older versions.

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