ESP32 As Your Raspberry Pi’s Linux Wireless Co-processor

A laptop with no wireless connectivity feels like a rarity – but when you shop for powerful Linux single-board computers (SBCs), it is pretty common to see one skimp on WiFi. At the same time, current wireless cards can leave much to be desired. A mess of proprietary firmware, ephemeral or even binary blob drivers, weird glitches never resolved, and sometimes entirely source-less blobs with an expiration date. Maybe the SBC doesn’t have a free USB port for a plug-and-play WiFi chip, or you don’t want to design for an obscure hard-to-source castellated module.

What if I told you there’s a unique solution to the problem, as long as the SBC has an SDIO or SPI to spare? There’s a wireless card we can all try to get behind, and it’s certainly not flawless but gives us way more room to grow – it’s got somewhat open-source firmware, it comes from a respectable company, and it’s nigh-guaranteed to be easy to source. I am, of course, talking about esp-hosted – using ESP32 modules as your WiFi/BT card, over SDIO or SPI.

I’ve recently added an ESP32-C6 into my project, and setting up esp-hosted wasn’t ultra straightforward – so here’s a guide, and a discussion on what makes esp-hosted so cool and so incredibly promising. Spoilers: it works with privacy switches that cut out power, it could be hacked into a coprocessor for mesh protocols, and it could potentially help us build a fully open-source SDIO WiFi card.

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Using LineageOS For Phones And DIY Smart TVs Is Pretty Nifty

Although Android is essentially just another Linux distribution, most people only experience it in the form of the rather restrictive and proprietary versions found on smartphones, tablets and smart TVs. While this is probably fine for the average person, there’s also a lot to be said for the more pure Android experience in the form of LineageOS.

With this fully open and community-supported version of Android you’re free to muck about with your hardware to your heart’s content, without annoyances like unremovable bloatware apps and restrictions on e.g. enabling developer mode.

Even more fun is that there are ports of LineageOS to systems such as the Raspberry Pi SBC, including in the Android TV configuration. This means that not only can your ten year old Android phone get a make-over with a recent version of Android, you can also create your own Android TV-based smart TV without all the spying and other nasty things that commercial smart TVs love to do.

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How A British Engineer Homebrewed The Quietest Carbine

Hollywood has a lot to answer for when it comes to “silencers” on firearms. On screen, a suppressed pistol makes a pinging thud, and the bad guy in the next room flops to the floor. Real life is rather less cinematic. A suppressor takes the edge off the report, but it’s by no means quiet or silent. Hence why the term “silencer” is more of a colloquialism, and why “suppressor” is more appropriate.

Every so often, though, someone gets remarkably close to the movie version. The best-known example is probably the De Lisle carbine. A British commando weapon from the Second World War, it was cobbled together from bits and pieces and ended up being a stellar performer in the world of clandestine operations.

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Two diaphragm vacuum pump setups with high-tech jam jar vacuum vessel. (Credit: Maya Posch)

Vacuum Drying And Making Stuff Hot In A Vacuum

After previously exploring the impact of vapor pressure on the drying of desiccant and more, the conclusion was essentially that in order to drive moisture that’s not directly on a material’s surface out of it, you pretty much have to heat up said material to make the process not take forever. Of course, we’d still want to retain the vacuum while doing said heating, which raises the question of how you best heat something that is inside a vacuum.

Fortunately, this is a solved problem, with commentators to the previous article helpfully pointing to the existence of devices like vacuum ovens. Of course, you can either buy such a device and not worry your pretty little head about the finer details, or you can defy convention and build one yourself because you’re a rebel and really want to know how their internals work.

Thus in this article we’ll be taking a look at the finer details of generating thermal radiation and how to best heat up a sample inside a vacuum chamber without directly picking easy mode with microwaves.

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Roman Telescope Saves Fuel, Doubles Mission

Contemplate the events that might end a space mission, and you might picture something dramatic: detonation on the pad, a dead guidance system, or micrometeoroids shattering delicate solar panels. More often, though, the ending is far more mundane. Plenty of perfectly healthy spacecraft have been retired simply because the fuel tanks ran dry. That’s why mission planners guard every kilogram of go juice so jealously, and why careful preparation in a mission is critical to long-term success.

Which brings us to NASA’s Nancy Grace Roman Space Telescope. Barely two weeks after its August 30 launch on a Falcon Heavy, the mission team announced that Roman now has enough fuel for at least 22 years of science operations. That’s well over double its original 10-year fuel budget. It’s a huge gain, so let’s explore how NASA pulled it off.

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Geothermal Cooling For New York’s Subways

You might think that if you dug some tunnels down into the ground where you could be out of the sunshine, that you might find them to be relatively cool and comfortable inside. Yet, fill those tunnels with trains and supporting equipment and millions of commuters, and you’ll instead find yourself sweltering in the heat.

New York’s subways are too hot for comfort, and have been for some time. Unfortunately, unlike any old regular building, you can’t just air condition a subway and call it done. Instead, authorities are looking for other solutions to beat the heat on the famous underground transit network.

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The FPGA Chronicles: Exploring The Tang Nano 20K

FPGAs used to be mysterious, expensive devices, but these days you can buy surprisingly capable boards for very little money. Some years ago, I did an FPGA Bootcamp over on Hackaday.io. Much of that material still applies, but the hardware is dated. So I decided it was time to update it, using the inexpensive Tang Nano 20K and its GOWIN GW2AR-18 FPGA as the main platform, with perhaps a few excursions into other FPGAs.

History and Motivation

Once upon a time, if you wanted to have a custom IC, you went with a wheelbarrow full of money to a semiconductor company. However, some smart person at a semiconductor fab eventually realized they could make a chip with a lot of uncommitted blocks on it and then, for a custom chip, only design the wiring that connected them together. This still required a wheelbarrow full of money, but it was a smaller wheelbarrow.

Then one day, someone realized they could do the same thing but make the electrical connections between the blocks configurable. Maybe have fuses you can blow, or use EEPROM or RAM cells to remember which blocks are connected to which. It is complicated, sure, but then you can make many of these chips and sell them to people who could, in theory, make their own custom chips without your help.

When do you need an FPGA? A classic classroom exercise for an FPGA, for example, is a traffic light because it shows off how to do state machines, which are important for some kinds of FPGA designs. But other than as a learning example, why would you do this? Even a simple 8-bit CPU can handle a traffic light.

Suppose instead that you have hundreds of digital sensors on a rocket, and any one of them must raise an alarm within a few microseconds. A processor has to sample inputs in groups, service interrupts, or rely on extra hardware. An FPGA can simply implement the equivalent of one enormous OR gate. It watches every input continuously, and unrelated logic elsewhere in the FPGA does not steal execution time from it. Can you do it with a microcontroller? Probably, but not easily. For some classes of problems, an FPGA is the better answer.

Of course, you can also build a CPU on your FPGA and some FPGAs have CPUs in the same package. This is often a sweet spot because then things that are easy to do in software, you do in software. Things that are easier to do in hardware, you do in the FPGA.

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