Drawing Knots On An Oscilloscope Using Analog Means

February 22, 2023 by 13 Comments

Generating interesting imagery on an analog oscilloscope is a fun activity enjoyed by many, with an excellent demonstration by [Henry Segerman] provided in a recent video which covers [Matthias Goerner]’s demonstration. Using the electron beam, shapes can be drawn onto the phosphor of the oscilloscope’s CRT — all without touching any digital circuitry. At the core are analog components like an operational amplifier integrator, multipliers and other elements.

With just a number of these simple components in a circuit, it’s possible to draw a wide variety of shapes, all by applying the appropriate trigonometric parameters. In addition to the drawing of shapes, it is also demonstrated how these analog signals can be used for an analog audio synthesizer, and finally the image displayed on the oscilloscope is captured on Kodak (Polaroid) instant film, making the entire generating, processing and capturing chain fully analog.

While we’d be the last to campaign against digital electronics, it is fascinating to consider just how much can be done with analog electronics and a bit of mathematics. We assume that everyone did pay attention during math classes, making this a perfect chance to use all that knowledge of trigonometry.

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Linux Fu: Sharing Your Single WiFi

February 22, 2023 by 24 Comments

If you are trying to build a router or access point, you’ll need to dig into some of the details of networking that are normally hidden from you. But, for a normal WiFi connection, things mostly just work, even though that hasn’t always been the case. However, I ran into a special case the other day where I needed a little custom networking, and then I found a great answer to automate the whole process. It all comes down to hotel WiFi. How can you make your Linux laptop connect to a public WiFi spot and then rebroadcast it as a private WiFI network? In particular, I wanted to connect an older Chromecast to the network.

Hotel WiFi used to be expensive, but now, generally, it is free. There was a time when I carried a dedicated little box that could take a wired or wireless network and broadcast its own WiFi signal. These were actually fairly common, but you had to be careful as some would only broadcast a wired network connection. It was more difficult to make the wireless network share as a new wireless network, but some little travel routers could do it. Alternatively, you could install one of the open router firmware systems and set it up. But lately, I haven’t been carrying anything like that. With free WiFi, you can just connect your different devices directly to the network. But then there’s the Chromecast and the dreaded hotel login.

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IBM Wants You To Learn Tech

February 22, 2023 by 19 Comments

IBM — no stranger to anyone who works in the computing field — has launched a series of training modules on a site called skillsbuild.org. The site targets high school students, college students, and adult learners and offers tracks for jobs like cybersecurity analyst, IT support technician, Web developer, and data science. Several other companies are participating, such as Red Hat and Fortinet. The cost? The courses are free and you can earn digital credentials to show you’ve completed certain classes.

Even more interesting is that they have resources for schools and other organizations that want to leverage the material for students. There is even software that educators can download at no charge for classroom use. The material is available in a variety of languages, too. For more advanced topics, there’s also Cognitive class from IBM, also free and which also provides the same sort of credentials.

Apparently, the digital credentials are far more than just an electronic diploma. Employers you select can examine the credentials and see things like exams and results along with other information to help them understand your skill level.

Even though you’re reading Hackaday and probably already have a good roster of tech skills, this could be a nice way to get some documentation of what you know. If you work with kids or even adults that need tech skills, or you just want to add some to your resume, you can’t beat the cost. If you aren’t sure, there are some sample guest classes you can try without even registering.

We live in an amazing time when you can build your own college-level education. You can even “study” at MIT and other big institutions inexpensively or for free.

All About USB-C: Replying Low-Level PD

February 22, 2023 by 31 Comments

Last time, we configured the FUSB302 to receive USB PD messages, and successfully received a “capability advertisement” message from a USB-C PSU. Now we crack the PD specification open, parse the message, and then craft a reply that makes the PSU give us the highest voltage available.

How did the buffer contents look, again?

>>> b
b'\xe0\xa1a,\x91\x01\x08,\xd1\x02\x00\x13\xc1\x03\x00\xdc\xb0\x04\x00\xa5@\x06\x00<!\xdc\xc0H\xc6\xe7\xc6\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00'

The zeroes at the end might look non-significant, and they indeed are not with 99.99% certainty – that said, don’t just discard the entire tail end; one of the bytes in the beginning encodes the length of the message. We’ll read those bytes first, and then read only exactly as much as we need, making sure we aren’t reading two messages and interpreting it as one, and that we’re not discarding zeroes that are part of the message.

Today, we will write code that parses messages right after reading them from the FIFO buffer – however, keep this message handy for reference, still; and if you don’t have the hardware, you can use it to try your hand at decoding nevertheless. If you wanna jump in, you can find today’s full code here!

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Reverse Engineering The Apple Lightning Connector

February 22, 2023 by 7 Comments

A frequent contributor to the hacker community, [stacksmashing] has prepared an excellent instructional video on reverse engineering Apple’s Lighting connector proprietary protocol. The video begins by showing how to gain physical access to the signals and hooking them up to a logic analyzer. He then notes that the handshaking uses only a single signal and proposes that Apple isn’t going to re-invent the wheel (perhaps a risky assumption). Using a ChatGPT search, obligatory these days, we learn that Dallas Semiconductor / Microchip 1-wire is probably the protocol employed.

Which embedded single-wire busses exist that encode bits with different lengths of low and high signals?

At the basic level, 1-wire and protocols like Texas Instruments SDQ operate in a similar manner. It turns out that [stacksmashing] already wrote a SDQ analyzer module for the Saleae logic analyzer. Aided by this tool, he digs deeper and learns more about the kinds of messages and their contents. For example, upon being plugged in, the host system queries the accessory’s serial number, manufacturer, model number, and product description. Finally, he introduces the CRC reverse engineering tool reveng to determine which CRC polynomial and algorithm the protocol uses to frame each packet.

Even if you have no interest in Lightning cables, this video is a great tutorial on the types of things you need to do in order to make sense of an unknown communications protocol. Gather what information you can, make some educated guesses, observe the signals, revise your guesses, and repeat. In part two, [stacksmashing] will show how to build a homemade iPhone JTAG cable.

We wrote in more detail about cracking the Lightning interface back in 2015. The Lightning interface may have been a good solution in its day, foreshadowing some of the features we now have in USB-C. But its proprietary and closed nature meant it wasn’t used outside of the Apple ecosystem. With the proliferation and capabilities of USB-C, not to mention various legislative edicts, Lightning’s days seem numbered. Is the industry finally settling on one interface? Let us know your thoughts in the comments below.

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Electromagnetic Mechanism Makes Reconfigurable Antenna

February 22, 2023 by 10 Comments

Antennas are a key component to any RF gadget. But antennas often only perform well over a narrow band of frequencies. For some applications, this is acceptable, but often you would like to reconfigure an antenna for different bands. Researchers at Penn State say they’ve developed a tunable antenna using compliant mechanisms and electromagnets. The new scalable design could work in small areas to provide frequency agility or beamforming.

The prototype is a circular patch antenna made with 3D printing. If you want to read the actual paper, you can find it on Nature Communications.

A compliant mechanism is one that achieves force and motion through elastic body deformation. Think of a binder clip. There’s no hinge or bearing. Yet the part moves in a useful way, using its own deformation to open up or grip papers tightly. That’s an example of a compliant mechanism. This isn’t a new idea — the bow and arrow are another example. However, because 3D printing offers many opportunities to build and refine devices like this, interest in them have increased in recent years.

We couldn’t help but notice that the antenna is a variation of a “compliant iris” like the one in the video below. You can find designs for these online for 3D printing, so if you wanted to experiment,  you might think about starting there.

We’ve looked at compliant mechanisms before. Why would you want better chip-scale antennas? Why, indeed.

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Let Machine Learning Code An Infinite Variety Of Pong Games

February 21, 2023 by 7 Comments

In a very real way, Pong started the video game revolution. You wouldn’t have thought so at the time, with its simple gameplay, rudimentary controls, some very low-end sounds, and a cannibalized TV for a display, but the legendarily stuffed coinboxes tell the tale. Fast forward 50 years or so, and Pong has been largely reduced to a programmer’s exercise to see how few lines of code can stand in for what [Ted Dabney] and [Allan Alcorn] accomplished. But now even that’s too much, as OpenAI Codex can generate a playable Pong from just a few prompts, at least most of the time. Continue reading “Let Machine Learning Code An Infinite Variety Of Pong Games” →