A photo of the HAT with the LoRa module and relay visible on the top

LoRaSense Pi Hat Aims To Kick Start IoT Projects

August 5, 2025 by John Elliot V 8 Comments

[Avi Gupta] recently sent in their LoRaSense RGB Pi HAT project. This “HAT” (Hardware Attached to Top) is for any Raspberry Pi with 40-pin header. The core of the build is the custom printed circuit board which houses the components and interconnects. The components include an SHT31 temperature and humidity sensor, an SX1278 LoRa module, and a 10 amp 220 VAC relay. The interconnects include support for UART, I2C, SPI, and WS2812B RGB LED interfaces as well as a stackable header for daisy chaining HATs.

The attached components in combination support a wide range of use cases. Possible uses for this Raspberry Pi HAT include smart home systems, agricultural projects, industrial monitoring, smart greenhouse, remote weather stations, or alerting systems. You can detect weather conditions, send and receive information, switch mains powered loads, and use RGB LEDs for status and alerting.

If you’re interested in LoRa technology be sure to read about the Yagi antenna that sends LoRa signals farther.

Why Names Break Systems

August 5, 2025 by Ian Bos 75 Comments

Web systems are designed to be simple and reliable. Designing for the everyday person is the goal, but if you don’t consider the odd man out, they may encounter some problems. This is the everyday life for some people with names that often have unconsidered features, such as apostrophes or spaces. This is the life of [Luke O’Sullivan], who even had to fly under a different name than his legal one.

[O’Sullivan] is far from a rare surname, but presents an interesting challenge for many computer systems. Systems from the era of penny pinching every bit relied on ASCII. ASCII only included 128 characters, which included a very small set of special characters. Some systems didn’t even include some of these characters to reduce loading times. Throw on the security features put in place to prevent injection attacks, and you have a very unfriendly field for many uncommon names.

Unicode is a newer standard with over 150,000 characters, allowing for nearly any character. However, many older systems are far from easy or cheap to convert to the new standard. This leaves many people to have to adapt to the software rather than the software adapting to the user. While this is simply poor design in general, [O’Sullivan] makes sure to point out how demeaning this can be for many people. Imagine being told that your name isn’t important enough to be included, or told that it’s “invalid”.

One excuse that gets thrown about is the aforementioned injection prompts that can be used to affect these systems. This can cause systems to crash or even change settings; however, it’s not just these older systems that get affected. For modern-day injection prompts, check out how AI models can get affected!

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2025 One Hertz Challenge: Shoulda Put A Ring Oscillator On It

August 5, 2025 by Tyler August 12 Comments

Entries keep ticking in for the One Hertz Challenge, some more practical than others. [Pierre-Loup M.]’s One Hertz Sculpture has no pretensions of being anything but pretty, but we can absolutely respect the artistic impulse behind it.

The sculpture is a free-form circuit inside of a picture frame. There are 9 LEDs in a ring with a few other components to produce a reverse-chase effect (one going dark at a time) taking about 1 second to circle the sculpture. As far as free-form circuit art goes, it’s handsomely done, but as this is Hackaday it’s probably the electronics, rather that the aesthetics that are of interest.

The circuit is an example of a ring oscillator: a cascading chain of NOT gates, endlessly feeding into and inverting one

An animated gif of the sculpture at work — Without timing it, it looks like 1 Hz, even if we know it’s not.

another. The NOT gates are implemented in resistor-transistor logic with 2N3904 NPN transistors, nine in total. Of course the inverter delay of this sort of handmade logic gate is far too fast for an aesthetically pleasing (or visible) chase, so some extra circuitry is needed to slow down the oscillations to something less than the 5 MHz it would naturally do. This is affected by pairing every transistor with an RC oscillator. Ideally the RC oscillator would have a 0.111..s period (1/9th of a second), but a few things got in the way of that. The RC oscillator isn’t oscillating in a vacuum, and interactions with the rest of the circuit have it running just a little bit fast. That’s really of no matter; a simple oscillator circuit like this wasn’t going to be a shoe in for the accuracy-based Time Lords category of this contest. As a sculpture and not a clock, you’re not going to notice it isn’t running at exactly 1Hz. (Though a ring-oscillator based clock would be a sight indeed.)

We’ve seen ring oscillators before, including inside the venerable 8087 coprocessor and this delightfully romantic beating-heart gift, but this is the first one that seems to have entered the One Hertz Challenge.

If you have a hankering for hertz, the contest is still open, but you’d better get ticking! The contest closes August 19th.

Flex PCB Underlies The Watch Of The Future

August 5, 2025 by Tyler August 8 Comments

If you were at OpenSauce, you may have seen new Youtuber [Sahko] waltzing about with a retrofuturistic peice of jewelery that revealed itself as a very cool watch. If you weren’t, he’s his very first video on YouTube detailing the design and construction of this piece. We’ve embedded it below, and it’s worth a watch. (Pun intended, as always.)

The build was inspired by the delightful amber LED dot-matrix display modules that circle the band of the watch. They go by HCMS2901, but [Sahko] recommends using the HCMS3901 as it’s both more 3.3V-tolerant and easier to find now. A challenge in mounting so many displays was the voltage on the supply rail dropping below the logic level; presumably the newer version does not have this problem to the same degree. Either way we love the look of these little displays and are pondering projects of our own that might include them.

He’s got quite a few wrapped around his wrist, so at full brightness, all these displays draw one amp. That explains why like the LED watches of the 1970s, the default state of the displays is “OFF”. Even with a LiPo pouch salvaged from a disposable vape, the runtime would only be half an hour at full brightness without that periodicity. Luckily [Sahko] included buttons on the band of the watch to activate it and control the brightness so it isn’t always blasting at full. There are also different modes available, including a really cool waterfall effect you can see in the video.

The band is an interesting choice, too: it’s just a flex PCB. There’s nothing backing it, aside from its own stiffeners, which makes us very curious how well this watch would hold up to daily use. There’s no clasp in the traditional sense, either: the band is closed by a 4-pin connector that doubles as both charge and the USB programmer for the stm32u08 microcontroller that runs the displays. Conveniently for a watch, this version of the stm32 has an RTC, so it keeps time as well. We dig the minimalism of this design; it’s a great contrast to the maximalism of wrapping your wrist in displays.

We’ve seen very similar displays on an edge-viewed watch, but a tiny amber LED matrix never gets old. If you wrapping your wrist in all those tiny LEDs is too impractically power-hungry, try using Nixie tubes.

We’re always watching for projects– wrist mounted clocks or otherwise– so if you’ve got the time, please drop us a tip.

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2025 One Hertz Challenge: Blinking An LED The Very Old Fashioned Way

August 5, 2025 by Jenny List 10 Comments

Making an LED blink is usually achieved by interrupting its power supply, This can be achieved through any number of oscillator circuits, or even by means of a mechanical system and a switch. For the 2025 One Hertz Challenge though, [jeremy.geppert] has eschewed such means. Instead his LED is always on, and is made to flash by interrupting its light beam with a gap once a second.

This mechanical solution is achieved via a disk with a hole in it, rotating once a second. This is driven from a gear mounted on a 4.8 RPM geared synchronous motor, and the hack lies in getting those gears right. They’re laser cut from ply, from an SVG generated using an online gear designer. The large gear sits on the motor and the small gear on the back of the disk, which is mounted on a bearing. When powered up it spins at 60 RPM, and the LED flashes thus once a second.

We like this entry for its lateral thinking simplicity. The awesome 2025 One Hertz Challenge is still ongoing, so there is still plenty of time for you to join the fun!

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Get Your Tickets For Supercon 2025 Now!

August 5, 2025 by Tom Nardi 3 Comments

The wait is over — once this post hits the front page, ticket sales for the 2025 Hackaday Supercon will officially be live!

As is tradition, we’ve reserved 100 tickets priced at $148 (plus fees) for what we like to call the True-Believers. Those are the folks that are willing to sign up even without knowing who will be speaking or what this year’s badge looks like. Once those are sold out, the regular admission tickets will cost $296 (plus fees). We might be slightly biased, but even at full price, we like to think Supercon is a screaming deal.

Those who join us in Pasadena, California from October 31st through November 2nd can look forward to a weekend of talks, workshops, demos, and badge hacking. But what’s more, you’ll experience the unique sense of camaraderie that’s produced when you pack hundreds of hardware hackers into an alleyway and ply them with as much caffeine as they can handle. Some treat it like a normal hacker con, others as a social experiment, but nobody thinks of it as anything less than a fantastic time.

We’re still working closely with our friends at Supplyframe, DigiKey, and Framework to put together a full itinerary for Supercon 2025, so stay tuned over the coming weeks as things are finalized. But in the meantime, we’ve got a couple new additions this year that we’re pretty excited about.

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Student Drone Flies, Submerges

August 5, 2025 by Al Williams 17 Comments

Admit it. You’d get through boring classes in school by daydreaming of cool things you’d like to build. If you were like us, some of them were practical, but some of them were flights of fancy. Did you ever think of an airplane that could dive under the water? We did. So did some students at Aalborg University. The difference is they built theirs. Watch it do its thing in the video below.

As far as we can tell, the drone utilizes variable-pitch props to generate lift in the air and downward thrust in water. In addition to the direction of the thrust, water operations require a lower pitch to minimize drag. We’d be interested in seeing how it is all waterproofed, and we’re unsure how deep the device can go. No word on battery life either. From the video, we aren’t sure how maneuverable it is while submerged, but it does seem to have some control. It wouldn’t be hard to add a lateral thruster to improve underwater operations.

This isn’t the first vehicle of its kind (discounting fictional versions). Researchers at Rutgers created something similar in 2015, and we’ve seen other demonstrations, but this is still very well done, especially for a student project.

We did see a submersible drone built using parts from a flying drone. Cool, but not quite the same.

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