ATTiny NFC Thermometer keychain with keys

Tiny NFC-Powered Keychain Thermometer

December 8, 2024 by 9 Comments

What if your keychain could tell you the temperature, all while staying battery-free? That’s the essence of this innovative keychain ‘NFC_temp’ by [bjorn]. This nifty gadget harnesses energy from an NFC field—like the one created by your smartphone—to power itself just long enough to take a precise temperature reading. Using components like an ATTiny1626 microcontroller, a TMP117 thermometer, and an RF430CL330H NFC IC, NFC_temp cleverly stores harvested power in a capacitor to function autonomously.

The most impressive part? This palm-sized device (18×40 mm) uses a self-designed 13.56 MHz antenna to draw energy from NFC readers. The temperature is then displayed on the reader, with an impressive accuracy of ±0.1 °C. Creator [bjorn] even shared challenges, like switching from an analog sensor due to voltage instability, which ultimately led to his choice of the TMP117. Android phones work best with the tag, while iOS devices require a bit more angling for reliable detection.

Projects like NFC_temp underscore the creativity within open source. It’s a brilliant nod to the future of passive, wireless, energy-efficient designs. Since many of us will all be spending a lot of time around the Christmas tree this month, why not fit it in a bauble?

The Audiophile Carrot

December 8, 2024 by 31 Comments

The widely quoted carrot factoid that the vegetable’s orange colour is the result of patriotic Dutch farmers breeding them that way may be an urban myth, but it’s certainly true that they can pass an audio signal in a time of need. [Julian Krause] follows up on a Reddit meme of a carrot being used to join two phono plugs, and appears to find the organic interconnect to be of good quality.

We had to admit a second look at a calendar to be sure that it’s not April 1st, but while his manner is slightly tongue in cheek it seems he’s really characterising the audio performance of a carrot. What he finds is a bit of attenuation, some bass cut, and an intrusion of RF interference pickup, but surprisingly, not a bad distortion figure.

Of course, we’re guessing the real point of the exercise is to poke fun at the world of excessive hi-fi equipment, something we’ve been only too glad to have a go at ourselves from time to time. But if the tests are to be taken at face value it seems that in a pinch, a carrot will do as a means to hook together line level audio cables, no doubt lending a sweet and crunchy overtone to the result. The video is below the break, for your entertainment.

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Pixel mashup with Wasm-4 logo and retro graphics

WASM-4: Retro Game Dev Right In Your Browser

December 8, 2024 by 12 Comments

Have you ever dreamt of developing games that run on practically anything, from a modern browser to a microcontroller? Enter WASM-4, a minimalist fantasy console where constraints spark creativity. Unlike intimidating behemoths like Unity, WASM-4’s stripped-back specs challenge you to craft games within its 160×160 pixel display, four color palette, and 64 KB memory. Yes, you’ll curse at times, but as every tinkerer knows, limitations are the ultimate muse.

Born from the WebAssembly ecosystem, this console accepts “cartridges” in .wasm format. Any language that compiles to WebAssembly—be it Rust, Go, or AssemblyScript—can build games for it. The console’s emphasis on portability, with plans for microcontroller support, positions it as a playground for minimalist game developers. Multiplayer support? Check. Retro vibes? Double-check.

Entries from a 2022’s WASM-4 Game Jam showcase this quirky console’s charm. From pixel-perfect platformers to byte-sized RPGs, the creativity is staggering. One standout, “WasmAsteroids,” demonstrated real-time online multiplayer within these confines—proof that you don’t need sprawling engines to achieve cutting-edge design. This isn’t just about coding—it’s about coding smart. WASM-4 forces you to think like a retro engineer while indulging in modern convenience.

WASM-4 is a playground for anyone craving pure, unadulterated experimentation. Whether you’re a seasoned programmer or curious hobbyist, this console has the tools to spark something great.

Cheap FPGA PCIe Development

December 7, 2024 by 18 Comments

Typically, if you want to build an FPGA project inside a PC, you’d need a fairly expensive development board that plugs into the bus. However, [CircuitValley] found some IBM RS-485 boards that are little more than a PCIe board with an Intel FPGA onboard. These are widely avaiable on the surplus market for around $20 shipped. He’s been documenting how to use them.

The FPGA onboard is a Cyclone IV with about 21,000 logic elements and a little over 750 kbits of memory. The board itself has configuration memory, power management, and a few connectors. The JTAG header is unpopulated, but the footprint is there. You simply need to supply a surface-mount pin header and an external JTAG probe, and you can program. Even if you aren’t interested in using an FPGA board, the reverse engineer steps are fun to watch.

The situation reminds us a little of the RTL-SDR — when a device uses a programmable device to perform nearly all of its functions, it is subject to your reprogramming. What would you do with a custom PCIe card? You tell us. Need a refresher on the bus? We can help. Thinking of building some sort of FPGA accelerator? Maybe try RIFFA.

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A Look Inside IKEA’s Vallhorn Motion Sensor Teardown

December 7, 2024 by 25 Comments

A good source of hackable home automation parts has come for a while in the form of inexpensive modules offered by large retailers such as Lidl, or IKEA. They’re readily available and easy to play with, they work with open source hubs, so what’s not to like! As an example, [Circuit Valley] has an IKEA Vallhorn motion sensor for a teardown, it’s as you might expect, a passive infrared sensor (PIR) sensor coupled with a Zigbee interface.

Inside the ultrasonic welded case is a small PCB and a Fresnel lens on the inside of the top cover, and a small PCB for the electronics. We applaud the use of a Swiss Army knife can opener as a spudger. The interesting part comes in identifying the individual components: the Silicon Labs EFR32MG21 SoC is easy enough, but another mystery 8-pin chip is more elusive. The part number suggests an Analog Devices op-amp for signal conditioning the PIR output, but the pinout seems not to support it and from here we think it’s too expensive a part for a budget item like this.

There’s a handy header for talking to the SoC, which we’d love to report is open and ready to be hacked, but we’re not getting too optimistic. Even if not hackable though, we’re guessing many of you find uses for these things. Continue reading “A Look Inside IKEA’s Vallhorn Motion Sensor Teardown” →

Microchess Remembered

December 7, 2024 by 10 Comments

Playing chess has always been a bellwether for computers. The game isn’t trivial, but the rules are managably simple. However, the game is too complex to be easily solved entirely, so you have to use tricky software to play a credible game. Big computers do have an advantage, of course. But Microchess — arguably the first commercial game for home computers — was able to play on tiny machines like the Kim-1. [Joachim Froholt] interviewed [Peter Jennings] — the man behind Microchess to learn the whole story of its creation.

In 1960, [Jennings] was ten years old and had to persuade the local librarian to let him read adult books on electronics and computers. Five years later, a ham radio teletype and some circuitry helped him practice chess openings and was the first of many chess-playing machines he’d build or program.

Microchess itself took six months of painstaking programming, entering hex codes into the computer. Word leaked out from a user’s group meeting (where Microchess beat a human player), and [Jennings] was swamped with requests for the program. In late 1976, the program was offered for sale as a teletype listing or, for an extra $3, a cassette tape.

The program went on to be very successful and moved to other platforms. Commodore even made a special dedicated device based on the Kim-1 to play Microchess, a piece of hardware unique enough that [Michael Gardi] honored it with one of his phenomenal replicas.

The £25,000 Tom Evans Pre-Amp Repair And A Copyright Strike

December 7, 2024 by 103 Comments

We were recently notified by a reader that [Tom Evans] had filed a copyright claim against [Mark]’s repair video on his Mend it Mark YouTube channel, taking down said repair video as well as [Mark]’s delightful commentary. In a new video, [Mark] comments on this takedown and the implications. The biggest question is what exactly was copyrighted in the original video, which was tough because YouTube refused to pass on [Mark]’s questions or provide further details.

In this new video the entire repair is summarized once again using props instead of the actual pre-amp, which you can still catch a glimpse of in our earlier coverage of the repair. To summarize, there was one bad tantalum capacitor that caused issues for one channel, and the insides of this twenty-five thousand quid pre-amp looks like an artistic interpretation of a Jenga tower using PCBs. We hope that this new video does stay safe from further copyright strikes from an oddly vengeful manufacturer after said manufacturer event sent the defective unit to [Mark] for a repair challenge.

Since this purportedly ‘audiophile-level’ pre-amplifier uses no special circuits or filtering – just carefully matched opamps – this is one of those copyright strike cases that leave you scratching your head.

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