Transponder Mania

July 16, 2026 by Fenix Guthrie 26 Comments

In order to not hit something, you generally need to know where that thing is. On land, the meager human eyesight tends to be sufficient. On the water, however, the prospects are more dangerous and complicated. So, technology is required to ensure safe ocean voyages in the form of the AIS transponder system. The off the shelf solutions tend to work quite well, but [peterantypas] was displeased with the commercial offerings, and built what appears to be the first open source AIS transponder called MAIANA.

Automatic Identification System (AIS) is a GPS tracking system designed for maritime applications. Broadly speaking, it broadcasts GPS and other data at intervals over VHF radio. AIS is what allows the precise tracking of vessels by authorities, and online hobbyists. AIS is also often received by other vessels to augment radar improving boat to boat collision safety.

Most commercial AIS transponders used by sailors are rather bulky, expensive, come with a large power budget. The MAIANA project avoids these pitfalls by being entirely self-contained. The RF portion is largely made up of a STM32L4 micro controller, a SI Labs Si4460 ISM RF chip, and a Quectel L76L-M33 with a Johansson ceramic chip antenna for GPS. With such simple hardware, the PCB is easily small enough to fit inside the antenna assembly.

This design eliminates the need for long runs of multiple shielded RF cables to a bulky transponder unit inside. Instead, a simple Ethernet cable is used to transfer data to and from the mast. Inside the boat, a USB decoder is used to pass the AIS data on to a PC. This whole setup is remarkably simple and reliable, with hundreds of units having been produced since the project’s start.

While this is the first full blown AIS transponder we have covered, we have seen other projects utilizing the protocol. We have also seen quite a number of projects with the aircraft equivalent, ADS-B.

Thanks [Bernerd] for the tip!

Making A Locked Down Wearable Work Without A Subscription

July 15, 2026 by Fenix Guthrie 12 Comments

WHOOP does not have the presence in the wearable space as other brands, but in certain circles, it’s a household name. Their business model requires you to have a yearly app subscription to use their fitness tracker, but here at Hackaday, we are big fans of actually owning the devices you buy — which is why we were happy to hear about an open source and subscription free WHOOP compatible app!

The goal of the so-called OpenStrap project is not to re-create the WHOOP app. Rather, the algorithms and processing methods are developed from scratch, based on public research. It’s all calculated locally on a 1 Hz interval, based on the data the WHOOP 4.0 device feeds the app. As such, the health data collected from the watch, never leaves the phone. While not the main goal of the project, the privacy improvement of the app’s serverless nature cannot be overstated. However, to display metrics, you first need to get data off the WHOOP to begin with.

The crux of the issue with making the WHOOP 4.0 work without the official app is the reliance on proprietary Bluetooth protocols. Fortunately, the protocol itself ended up being relatively simple. The WHOOP 4.0 amounts to little more than a series of sensors that sit on the user’s wrist. As such, the app can subscribe to the Bluetooth feed and decode the data, right? Well, the devil is always in the details with such things, and the protocol came with its fair share of quirks. The hardware clock needs to be synchronized, or it simply defaults to zero Unix time. Moreover, the analog sensors like, ambient temperature are given in relative ADC values, and are not terribly useful without calibration. Regardless, the result of the reverse engineering effort speaks for itself with the OpenStrap app able to recreate much of the functionality in WHOOP’s official app.

Quite often, devices reliant on proprietary apps are little more than manufactured e-waste. While we don’t expect many of you to actually own a WHOOP 4.0, we do hope to see the OpenStrap project keep at least a few out of the landfill in the future.

Performance Improvements For Open-Source 80386

July 6, 2026 by Fenix Guthrie 4 Comments

The Intel 80386 is a rather fascinating slice of computer history. It marked the first 32 bit X86 processor, and was a staple of early desktop computing. Like all chips, it has a number of quirks, one of which being the fact that all commands are executed in microcode. By this nature, it was a rather excellent prospect to be re-implemented in an FPGA core called the z386. However, it was lacking a feature native to the original 386, early start memory access. So to bring some performance to the z386 project, [nand2mario] went forth to fully implement this feature for FPGA 80386s.

Instead of taking a cycle to find and allocate the memory required for executing the next instruction, the 386 would start this in the previous cycle. This is achieved in hardware by nature of having a separate memory management unit. In the FPGA, the key difficulty proved to be in getting the computation fast enough to execute within a single cycle. This change netted an approximate 9% performance benefit. However, for [nand2mario] this was too small a performance uplift.

Some rewrites of the store cue allowed for cutting a cycle out of the process further improving the performance. However, more performance required slight deviations from the design of the original 386. Because code-branches are performance critical, the z386 project now computes the branch memory jump several cycles earlier than the 386, reducing the cycle time for the jumps from 9.25 to a mere 6. Some final changes to the microcode decode frontend rounded out the optimizations covered in this latest blog post.

The net result is an approximate 39% increase in performance in the all important DOOM benchmark. The z386 still not a complete project, the performance is still lacking compared to the 386, and it remains unable to boot Windows. X86 is complicated, which will take time, so make sure to stay tuned for more coverage! While you wait, make sure to check out our original writeup of the z386 project.

Pauli Rautakorpi, CC BY 3.0.

Double The VRAM Of An RTX 3070

June 14, 2026 by Fenix Guthrie 22 Comments

Modern games are quite often limited by the amount of volatile memory available to the GPU. Games can require many gigabytes of data during the rasterization process. So the obvious solution for better performance would be to buy a faster GPU, right? Well, not for [AssassinWarlord], who decided to find just what happens when you double the VRAM on an RTX 3070. The forum post is in German, but a translator gets the job done rather nicely.

For those of you following along at home, you will need a set of eight Samsung K4ZAF325BM-HC16 GDDR6 memory modules. In this case, the memory modules were salvaged from an AMD RX6900XT with a defective core. Naturally, you will need to re-ball the chips. To help the process, [AssassinWarlord] bought a stencil from AliExpress, with a 3D-printed holder for the memory modules.

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Hear Ye, Hear Ye! The Magic Of The Scroll-Like Phone Which Wast Not!

April 7, 2026 by Fenix Guthrie 11 Comments

When LG left the smartphone market, quite a number of strange devices were left behind. While some, like the Wing, made it to consumers, others did not. The strangest of these would have to be their rollable phone concept; a device which would expand by unrolling a portion of the screen like a scroll. This never made it to market, but one managed to make its way to [JerryRigEverything’s] workbench, and we are fortunate enough to see the insides of this strange device.

There are a few interesting tidbits about the device before even entering the device. Very clearly this phone was ready to be sold, with a tidy user interface for expanding the display, and even animated wallpapers which expand with it. The display, when rolled onto the back of the device, sits behind a glass cover to keep it protected from debris, and can be used to take selfies with the larger sensors of the rear facing cameras. You can also see a bit of the track that the screen rolls on, hinting at what lies inside.

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Simulating The AVR8 For A Browser-based Arduino Emulator

April 6, 2026 by Fenix Guthrie 10 Comments

It’s always nice to simulate a project before soldering a board together. Tools like QUCS run locally and work quite well for analog circuits, but can fall short with programmable logic. Tools like Wokwi handle the programmable side quite well but may have license issues or require the cloud. The Velxio project by [David Montero Crespo] is quite an excellent example of an (online) circuit simulator with programmable logic and local execution!

It’s built largely around Wowki’s AVR8JS library for Arduino simulation. All CPU simulation occurs on the local computer, while sketch compilation happens on the backend using official Arduino tools. But this was certainly not the most impressive aspect of the project. Likewise, Velxio features RP2040 execution using the rp2040js library. It also features the execution of some ESP32 derivative boards built around the RISC-V architecture using the RiscVCore.ts library.

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Looking At A Bike Built For The Apocalypse

March 26, 2026 by Fenix Guthrie 17 Comments

So-called bug out cars are a rather silly venture that serve little purpose more than snagging your jumper. The odds of a car working well through a nuclear winter are rather minimal. But what about a bicycle? On paper it’s a better choice, with extreme efficiency, reliability, and runs off whatever sustenance you can find in the barren landscape of a collapsed society. But [Seth] over at Berm Peak proved an apocalypse bike is at least as silly as a bug out car.

While a utilitarian bike fit for a cross-country trek across a nuclear wasteland can certainly be a reasonable venture, this particular bicycle is not that. This three wheeled monstrosity of a bicycle (is it still a bicycle if it has three wheels?) was built by [TOMO] for the Bespoked bike show’s apocalypse buildoff. It placed second among a number of strange bikes with features ranging from pedal driven circular saws to beer keg grills. But this particular example of apocalypse bike is easily the strangest example of the lot.

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