New Years Circuit Challenge: Make This RFID Circuit

December 31, 2024 by 9 Comments
A 125kHz PCB antenna, a spiral pattern on a PCB.
The Proxmark3 PCB 125kHz antenna., GNU GPL version 2, GitHub link.

Picture this: It’s the end of the year, and a few hardy souls gather in a hackerspace to enjoy a bit of seasonal food and hang out. Conversation turns to the Flipper Zero, and aspects of its design, and one of the parts we end up talking about is its built-in 125 kHz RFID reader.

It’s a surprisingly complex circuit with a lot of filter components and a mild mystery surrounding the use of a GPIO to pulse the receive side of its detector through a capacitor. One thing led to another as we figured out how it worked, and as part of the jolity we ended up with one member making a simple RFID reader on the bench.

Just a signal generator making a 125 kHz square wave, coupled to a two transistor buffer pumping a tuned circuit. The tuned circuit is the coil scavenged from an old RFID card, and the capacitor is picked for resonance in roughly the right place. We were rewarded with the serial bitstream overlaying the carrier on our ‘scope, and had we added a filter and a comparator we could have resolved it with a microcontroller. My apologies, probably due to a few festive beers I failed to capture a picture of this momentous event. Continue reading “New Years Circuit Challenge: Make This RFID Circuit” →

VPlayer Puts Smart Display In Palm Of Your Hand

December 31, 2024 by 18 Comments

It’s not something we always think about, but the reality is that many of the affordable electronic components we enjoy today are only available to us because they’re surplus parts intended for commercial applications. The only reason you can pick up something like a temperature sensor for literal pennies is because somebody decided to produce millions of them for inclusion in various consumer doodads, and you just happened to luck out.

The vPlayer, from [Kevin Darrah] is a perfect example. Combining a 1.69 inch touch screen intended for smartwatches with the ESP32-S3, the vPlayer is a programmable network-connected display that can show…well, pretty much anything you want, within reason. As demonstrated in the video below, applications range from showing your computer’s system stats to pulling in live images and videos from the Internet.

Continue reading “VPlayer Puts Smart Display In Palm Of Your Hand” →

Lowering Your Noise Floor, The Easy Way

December 31, 2024 by 35 Comments

If there’s anything more annoying to an amateur radio operator than noise, we’re not sure what it could be. We’re talking about radio frequency noise, of course, the random broadband emissions that threaten to make it almost impossible to work the bands and pick out weak signals. This man-made interference is known as “QRM” in ham parlance, and it has become almost intolerable of late, as poorly engineered switch-mode power supplies have become more common.

But hams love a technical challenge, so when a nasty case of QRM raised its ugly head, [Kevin Loughlin (KB9RLW)] fought back. With an unacceptable noise floor of S8, he went on a search for the guilty party, and in the simplest way possible — he started flipping circuit breakers. Sure, he could have pulled out something fancier like a TinySA spectrum analyzer, but with his HF rig on and blasting white noise, it was far easier to just work through the circuits one by one to narrow the source down. His noise problem went away with the living room breaker, which led to pulling plugs one by one until he located the culprit: a Roomba vacuum’s charging station.

Yes, this is a simple trick, but one that’s worth remembering as at least a first pass when QRM problems creep up. It probably won’t help if the source is coming from a neighbor’s house, but it’s a least worth a shot before going to more involved steps. As for remediation, [Kevin] opts to just unplug the Roomba when he wants to work the bands, but if you find that something like an Ethernet cable is causing your QRM issue, you might have to try different measures.

Continue reading “Lowering Your Noise Floor, The Easy Way” →

Sega Dreamcast console banner image

Fan Made Dreamcast Port Of GTA 3 Steals The Show

December 30, 2024 by 15 Comments

As it turns out, Sega’s long defunct Dreamcast console is still thinking. The company behind the machine cut support long ago due in part to the commercial pressures applied by Sony’s PlayStation 2 console, but that never stopped the most dedicated of Dreamcast fans from seeking out its true potential. Thanks to [Stefanos] and his team, the genre defining Grand Theft Auto III (GTA 3), can now run on Sega’s hardware. Their combined efforts have yielded a fully playable port of the PC version of the game for the Dreamcast.

The porting effort was years in the making. It began with reverse engineering the entire source code of GTA 3 then implementing it into the homebrew SDK for the Dreamcast, KallistiOS. All the in-game graphic and sound assets are only pulled from a user provided PC copy of the game. Steps for those seeking to compile a bootable Dreamcast image of their own have been provided on the project’s website. Real hardware enthusiasts will be pleased as the port runs fine on the twenty-five year old Dreamcast as evidenced in the video below.

This port of GTA 3 represents what could have been a true butterfly effect moment in console gaming history. The game was a major hit in the early days of the PlayStation 2, and it has been theorized that it could have proven to be a major commercial success for Sega as well had it been pressed onto a Dreamcast GD-ROM disc. Recently one of the original developers of GTA 3, Obbe Vermejj, divulged that the game actually began development on the Dreamcast. The project was obviously transferred onto PlayStation 2 for commercial reasons, but with this port from [Stefanos] and crew we no longer have to dream of what could have been.

Continue reading “Fan Made Dreamcast Port Of GTA 3 Steals The Show” →

Different potato varieties. – The potato is the vegetable of choice in the United States. On average, Americans devour about 65 kg of them per year. New potato releases by ARS scientists give us even more choices of potatoes to eat. (Credit: Scott Bauer, USDA ARS)

Re-engineering Potatoes To Remove Their All-Natural Toxins

December 30, 2024 by 66 Comments

Family Solanum (nightshade) is generally associated with toxins, and for good reasons, as most of the plants in this family are poisonous. This includes some of everyone’s favorite staple vegetables: potatoes, tomatoes and eggplant, with especially potatoes responsible for many poisonings each year. In the case of harvested potatoes, the chemical responsible (steroidal glycoalkaloids, or SGA) is produced when the potato begins to sprout. Now a team of researchers at the University of California have found a way to silence the production of the responsible protein: GAME15.

The research was published in Science, following earlier research by the Max Planck Institute. The researchers deleted the gene responsible for GAME15 in Solanum nigrum (black nightshade) to confirm that the thus modified plants produced no SGA. In the case of black nightshade there is not a real need to modify them as – like with tomatoes – the very tasty black berries they produce are free of SGA, and you should not eat the SGA-filled and very bitter green berries anyway, but it makes for a good test subject.

Ultimately the main benefits of this research appear to be in enriching our general understanding of these self-toxicity mechanisms of plants, and in making safer potatoes that can be stored without worries about them suddenly becoming toxic to eat.

Top image: Different potato varieties. (Credit: Scott Bauer, USDA ARS)

When The EU Speaks, Everyone Charges The Same Way

December 30, 2024 by 98 Comments

The moment everyone has been talking about for years has finally arrived, the European Union’s mandating of USB charging on all portable electronic devices is now in force. While it does not extend beyond Europe, it means that there is a de facto abandonment of proprietary chargers in other territories too. It applies to all mobile phones, tablets, digital cameras, headphones, headsets, game consoles, portable speakers, e-readers, keyboards, mice, portable navigation systems and earbuds, and from early 2026 it will be extended to laptops.

Hackaday readers will probably not need persuading as to the benefits of a unified charger, and truth be told, there will be very few devices that haven’t made the change already. But perhaps there’s something more interesting at work here, for this moment seals the place of USB-C as a DC power connector rather than as a data connector that can also deliver power.

Back in 2016 we lamented the parlous state of low voltage DC power standards, and in the time since then we’ve arrived at a standard involving ubiquitous and commoditised power supplies, cables, and modules which we can use for almost any reasonable power requirement. You can thank the EU for that mobile phone now having the same socket as its competitor, but you can thank the USB Implementers Forum for making DC power much simpler.

38C3: Save Your Satellite With These Three Simple Tricks

December 30, 2024 by 11 Comments

BEESAT-1 is a 1U cubesat launched in 2009 by the Technical University of Berlin. Like all good satellites, it has redundant computers onboard, so when the first one failed in 2011, it just switched over to the second. And when the backup failed in 2013, well, the satellite was “dead” — or rather sending back all zeroes. Until [PistonMiner] took a look at it, that is.

Getting the job done required debugging the firmware remotely — like 700 km remotely. Because it was sending back all zeroes, but sending back valid zeroes, that meant there was something wrong either in the data collection or the assembly of the telemetry frames. A quick experiment confirmed that the assembly routine fired off very infrequently, which was a parameter that’s modifiable in SRAM. Setting a shorter assembly time lead to success: valid telemetry frame.

Then comes the job of patching the bird in flight. [PistonMiner] pulled the flash down, and cobbled together a model of the satellite to practice with in the lab. And that’s when they discovered that the satellite doesn’t support software upload to flash, but does allow writing parameter words. The hack was an abuse of the fact that the original code was written in C++. Intercepting the vtables let them run their own commands without the flash read and write conflicting.

Of course, nothing is that easy. Bugs upon bugs, combined with the short communication window, made it even more challenging. And then there was the bizarre bit with the camera firing off after every flash dump because of a missing break in a case statement. But the camera never worked anyway, because the firmware didn’t get finished before launch.

Challenge accepted: [PistonMiner] got it working, and after fifteen years in space, and ten years of being “dead”, BEESAT-1 was taking photos again. What caused the initial problem? NAND flash memory needs to be cleared to zeroes before it’s written, and a bug in the code lead to a long pause between the two, during which a watchdog timeout fired and the satellite reset, blanking the flash.

This talk is absolutely fantastic, but may be of limited practical use unless you have a long-dormant satellite to play around with. We can nearly guarantee that after watching this talk, you will wish that you did. If so, the Orbital Index can help you get started.