Month: January 2020

Magic Acrylic Makes This Ring Stand Out

January 17, 2020 by 9 Comments

LEDs look great no matter how you use them, but sometimes you want to hide them from direct view. [Charlyn] found a great way to do that, using a special material designed just for the purpose.

[Charlyn] built a ring as a piece of fashion jewelry, hooking up a Gemma M0 microcontroller to a Neopixel Jewel, which packs 7 individual LEDs. The hardware is secreted away inside an enclosure featuring both 3D-printed and lasercut parts.

Rather than openly show off the electronics, it’s all hidden away inside. Instead, a piece of black Chemcast LED acrylic is used, which allows LED light to shine through, while otherwise appearing opaque. Those interested in learning more can check out the product details on the manufacturer site.

It’s a great way to make a subtle costume piece that only reveals its flashier side when you so decide. We’ve seen badges use similar techniques on PCBs to great effect, too. Video after the break.

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This Week In Security: Windows 10 Apocalypse, Paypal Problems, And Cablehaunt

January 17, 2020 by 18 Comments

Nicely timed to drop on the final day of Windows 7 support, Windows 10 received a fix to an extremely serious flaw in crypt32.dll. This flaw was reported by the good guys at the NSA. (We know it was the good guys, because they reported it rather than used it to spy on us.) It’s really bad. If you’re running Windows 10, go grab the update now. OK, you’re updated? Good, let’s talk about it now.

The flaw applies to X.509 keys that use elliptic curve cryptography. We’ve discussed ECC in the past, but let’s review. Public key encryption is based on the idea that some calculations are very easy to perform and verify, but extremely difficult to calculate the reverse operation.

The historic calculation is multiplying large primes, as it’s unreasonably difficult to factorize that result by a conventional computer. A true quantum computer with enough qubits will theoretically be able to factorize those numbers much quicker than a classical computer, so the crypto community has been searching for a replacement for years. The elliptic curve is the solution that has become the most popular. An agreed-upon curve and initial vector are all that is needed to perform the ECC calculation.

There are potential weaknesses in ECC. One such weakness is that not all curves are created equal. A well constructed curve results in good cryptography, but there are weak curves that result in breakable encryption.

With that foundation laid, the flaw itself is relatively easy to understand. An X.509 certificate can define its own curve. The Windows 10 implementation doesn’t properly check the curve that is specified. A malicious curve is specified that is similar to the expected curve — similar enough that the checks in crypt32 don’t catch it. Continue reading “This Week In Security: Windows 10 Apocalypse, Paypal Problems, And Cablehaunt” →

A Water Cooled Gaming PC You Can Take With You

January 17, 2020 by 39 Comments

Have you ever been stuck in a hotel room wishing you brought your VR-capable gaming PC along with you? Well [thegarbz] certainly has, which was the inspiration for this absolutely gorgeous mobile rig affectionately known as “The Nuclear Football” that brings console-level portability to those who count themselves among the PC Master Race.

OK, fine. We’ll admit that the existence of gaming laptops means you don’t actually need to carry around such an elaborate contraption just to play Steam games on the go. But if you’re going to do it, shouldn’t you do it in style? More practically speaking, [thegarbz] says the cost of this project was less than what a gaming laptop of similar specs would have cost.

The Nuclear Football features a Ryzen 5 2600 processor, a NVIDIA 2070 Super graphics card, and 16 GB of DDR4 RAM. The water cooling gear is from Alphacool, and includes a custom controller that links to the computer and allows [thegarbz] to monitor temperatures and fan speeds via a widget on the desktop.

While not nearly as mobile, this machine does remind us of the water cooled “Big O” that packed all the current-gen consoles and a gaming PC into one glorious machine.

Oceanography As Open As The Seas

January 17, 2020 by 12 Comments

With Earth in the throes of climate change and no suitable Planet B lined up just yet, oceanography is as important now as it has ever been. And yet, the instruments relied upon for decades to test ocean conditions are holding steady within the range of expensive to prohibitively expensive. Like any other area of science, lowering the barrier of entry has almost no disadvantages — more players means more data, and that means more insight into the inner workings of the briny deep.

[Oceanography for Everyone] aims to change all that by showing the world just how easy it is to build an oceanographic testing suite that measures conductivity (aka salinity), temperature, and depth using common components. OpenCTD is designed primarily for use on the continental shelf, and has been successfully tested to a depth of 100 meters.

An Adalogger M0 and RTC Featherwing run the show from their waterproof booth in the center of the PVC tube. There’s a 14-bar pressure sensor for depth, a trio of DS18B20s for temperature averaging, and a commercial conductivity probe that gathers salinity data. These sensors are fed through a 3D-printed base plate and ultimately potted in stainless steel epoxy. The other end of the tube is sealed with a mechanical plug that seats and unseats with the whirl of a wingnut.

We particularly like the scratch-built magnetic slide switch that turns OpenCTD on and off without the need to open the cylinder. If you’d like to build one of these for yourself, take a deep dive into [Oceanography for Everyone]’s comprehensive guide — it covers the components, construction, and calibration in remarkable detail. The switch is explained starting on page 50. You can find out more about the work Oceanography for Everyone is doing at their site.

As far as cheap waterproof enclosures go, PVC is a great choice. It works well for underwater photography, too.

A Simple App Controlled Door Lock

January 16, 2020 by 9 Comments

[Adnan.R.Khan] had a sliding door latch plus an Arduino, and hacked together this cool but simple app controlled door lock.

Mechanically the lock consists of a Solarbotics GM3 motor, some Meccano, and a servo arm. A string is tied between two pulleys and looped around the slide of a barrel latch. When the motor moves back and forth it’s enough to slide the lock in and out. Electronically an Arduino and a Bluetooth module provide the electronics. The system runs from a 9V battery, and we’re interested to know whether there were any tricks pulled to make the battery last.

The system’s software is a simple program built in MIT App Inventor. Still, it’s pretty cool that you can get functionally close to a production product with parts that are very much lying around. It also makes us think of maybe keeping our childhood Meccano sets a little closer to the bench!

These Bit Twiddling Tricks Will Make Your Coworkers Hate You

January 16, 2020 by 32 Comments

In the embedded world, twiddling a few bits is expected behavior. Firmware is far enough down the stack that the author may care about the number of bits and bytes used, or needs to work with registers directly to make the machine dance. Usually these operations are confined to the typical shifting and masking but sometimes a problem calls for more exotic solutions. If you need to descend down these dark depths you invariably come across the classic Bit Twiddling Hacks collected by [Sean Eron Anderson]. Here be dragons.

Discussions of bit math are great opportunities to revisit Wikipedia’s superb illustrations

Bit Twiddling Hacks is exactly as described; a page full of snippets and suggestions for how to perform all manner of bit math in convenient or efficient ways. To our surprise upon reading the disclaimer at the top of the page, [Sean] observes that so many people have used the contents of the page that it’s effectively all been thoroughly tested. Considering how esoteric some of the snippets are we’d love to know how the darkest corners found use.

The page contains a variety of nifty tricks. Interview content like counting set bits makes an early appearance.  There’s more esoteric content like this trick for interleaving the bits in two u16’s into a single u32, or rounding up to the next power of two by casting floats. This author has only been forced to turn to Bit Twiddling Hacks on one occasion: to sign extend the output from an unfortunately designed sensor with unusual length registers.

Next time you need to perform an operation with bitmatch, check out Bit Twiddling Hacks. Have you ever needed it in production? How did you use it? We’d love to hear about it in the comments.

74-Series Clock Gets A MEMS Heart

January 16, 2020 by 15 Comments

[Erik van Zijst] has had a long career as a programmer, but lacked an understanding of what was happening at a bare metal level. After building a few logic gates out of transistors to get a feel for electronics, he set out to build a working clock using 74-series logic. Naturally, it was quite the adventure. 

The project starts out as many do on the breadboard. The requisite BCD counters and 7-segment displays were sourced, and everything was connected up with a cavalcade of colorful hookup wires. A 32.768 KHz crystal was pressed into service to generate the clock signal, divided down to get a 1Hz output to drive the seconds counter that would then run the entire clock. [Erik] then had to learn some more practical electronics skills, to deal with debouncing buttons for the time setting circuit.

With the clock now functional, [Erik] decided to take things further, aiming to build something more robust and usable. An automatic brightness control was created using a 555 to run a crude PWM dimmer for the LEDs. Additionally, a PCB was designed to replace the temporary breadboard setup. This led to problems with the oscillator that [Erik] couldn’t quite figure out. Rather than continue on the same path, he changed tack, instead replacing the quartz crystal with a modern MEMS oscillator that solved the problem.

It’s a great look at how to construct a working clock from bare logic, and one that serves to remind us just how complex even a seemingly simple device can be. We’ve seen other from-scratch builds before too, like this 777-transistor clock, or this attractive stacked design. Video after the break.

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