TechyMagThings

[Bas BotBerg] wanted to use a portable Bluetooth thermal printer to run off reports on sensor data collected by an ESP32-C3 microcontroller. But as is so often the case these days, the only official way to interface with the printer was through a proprietary smartphone application provided by the manufacturer. With no documentation on how the thing works, he set out to reverse engineer the printer’s communications protocol so he could control it from the MCU — but the route he took to get there was a bit different than what we usually see, and is an excellent case study for those who might have similar projects in mind.

The standard procedure for something like this, if it can be called that, is to use Android’s built-in debugging capability to log Bluetooth communications while running the manufacturer’s application. The resulting file can be fed into Wireshark, and with patience and some educated guesses, you can usually work out the various commands and values that get passed to the hardware.

But in this case, [Bas BotBerg] ignored the manufacturer’s software and instead used an application that can query a device and list its Bluetooth Low Energy services and characteristics. Specifically, he looks for services that are marked as writable, and starts pushing data into them to see how the printer responds. For this he uses Python with the Bleak library, as it allows him to rapidly iterate and adapt his code. After a bit of poking and experimentation, he finds the proper incantation to get the printer’s motor to kick on an advance the paper — a critical first milestone that tells him he’s on the right path.

Once [Bas BotBerg] mapped out what data needed to be sent to what endpoints to operate the printer in Python, it was a relatively straightforward process to send those same payloads using C++ code on the ESP32. For extra style points he also brought in the Adafruit GFX library so he could produce icons and more easily format the output of the printer.

It doesn’t look like [Bas BotBerg] has released the code in this case (perhaps if we all ask nicely), but we’ve seen similar efforts to bring open source drivers to these cheap Bluetooth printers for the good of the community.

Being able to monitor voltages and currents is essential for many applications, with the national electrical grid being no exception. The obvious complication here is that the voltages and currents are massively higher than for those other applications, making safely monitoring these somewhat of an engineering challenge. The used systems for current monitoring are detailed by [Jordan Taylor], also known as [The Electric Brit], in an explainer of grid-level current transformers (CTs) and associated elements that help to provide galvanic isolation for safe current measurements.

Even if the basic principles remain the same, when you’re dealing with currents of 5 kA and more, the associated clearances and penalties for getting a detail wrong increasingly correspondingly. The CTs help to implement over-current protection (OCP), over-voltage protection (OVP) as well as differential protection, which is useful to detect leakage and shorts, which could also happen inside the CT if the windings become damaged.

Any such failure condition can trigger a circuit breaker to be tripped, or other corrective measures to be taken. Incidentally this also how it can be detected when someone is tapping off power in an illicit manner. As with all transformers they’re never perfect due to issues like core saturation, and thus performing accurate measurements and picking the right type of transformer is an art in itself, as explained in the video.

Ultimately CTs and the associated equipment are what makes an AC power grid responsive to any changes and with it into the reliable foundation of modern-day society.

There are many uninterruptible power supply (UPS) solutions for the Raspberry Pi that take the form of HATs with a battery on board, but they’re not suitable for every situation. Web3-Pi are using the Pi 5 as an Ethereum node, and found the need for a UPS that didn’t sit on top of the Pi. Their solution is the Web3 Pi UPS, a device that sits in the USB power chain.

It’s a box that takes three power inputs, USB-C PD, a barrel jack, or a hot-swappable Sony camera battery, and puts out the constant 5 V at 5 A the Pi requires. The USB output isn’t just for power, it can communicate with the Pi to deliver telemetry and ask the OS to shut itself down if power reserves are failing. Inside are a CH32 RISC-V microcontroller that handles the power circuitry, and an RP2040 that handles control and an OLED screen for a UI. The project’s web site also mentions provision for an LTE add-on for remote monitoring, however this doesn’t at the time of writing appear to be fully implemented in the GitHub repository.

While it’s probable that few of you are mining Ethereum on your PI, we can see that there are plenty of other situations that this project could find a home in. It’s not the first Pi UPS we’ve seen, though some of them are considerably less complex or capable.

As any science YouTuber or first-year physics student is quick to point out, the universe is mostly empty space. Not just space itself, but the amount of “empty” space between nuclei and their electrons is also huge. Getting rid of this empty space results in all kinds of interesting phenomena like degenerate matter and black holes. But the concept can be extrapolated into our daily lives as well; many things are so filled with air that we can get a lot more usable storage space by compressing them down a little bit. [Super Valid Designs] took this concept to a coat closet, building one that can hold an impressive number of coats.

He started by looking at an existing closet, which could hold around 21 coats but only if someone used two hands to cram the coats into the space. After a trip to a store which sells rugs, he saw a much better design that lets all the rugs pivot like the pages on a book, and took this idea to his closet using a similar mechanism designed for storing large blueprints instead of rugs. The closet he built around this mechanism has two hinged doors which allow a person easy access to the coats, and when opened the blueprint hangers pivot out like a book, allowing the coats to not only be easily accessed without disrupting the other coats, but also allow them to be compressed down by the closet door for storage.

For comparison, the original closet could only hold 10 coats when restricted to single-hand operation and 21 when using both. The new closet design is smaller, and can hold 24 coats with a single hand and over 30 when using both, a dramatic improvement of closet efficiency. To top it off, a set of cupboards on top and bottom allow for storing shoes and hats as well, and there’s even a garage for a robotic vacuum cleaner. Surprisingly, we don’t see many closet optimization builds around here. The closest we can come is another traditionally small space, a college dorm.

After the Orion capsule of the Artemis I lunar mission returned to Earth, it was found that massive chunks of its heatshield had been ripped off, posing a serious risk to any future missions. In a recent video in which [polymatt] takes a break from repairing old laptop shells and the like, he tries to recreate the Orion’s heatshield using a variety of methods and materials.

For this test a number of samples were created, each using the same kind of segmented structure as the larger Orion heatshield. The filler was created from the published materials for the heat shield by NASA, requiring just serious mixing.

The resulting samples were then cured with thermocouples inserted, before they got blasted with the heat from a propane torch, trying to simulate the various re-entry patterns.

Perhaps unsurprisingly, the results matched the findings by NASA for why the Orion’s heat shield had failed, being the build-up of gases due to the sustained pyrolysis processes that eventually fractured the material. Despite some experimental flaws that injected residual heat from the copper structure, this still seems to be a pretty good setup to test ablative heat shields in DIY lab conditions.

We try to steer clear of politics and societal issues here at Hackaday, so a protest is not usually the sort of thing we’d cover. But we figure it’s safe enough to bend the rules a bit when the ones doing the protesting happen to be robots.

About 30 bots gathered — or at least were commanded to gather by the event organizers — in Warsaw to spur discussion about the impact AI and robots will have on the labor market. Beyond getting public and media attention, the demonstration was also designed to raise awareness of what modern humanoid robots can do. While we appreciate the idea of showing robots taking the “jobs” of the protesters, it does seem somewhat ironic that marching around and chanting for hours is exactly the sort of repetitive work that most people would be happy to see taken over by machines.

Although we hope these protests remain peaceful, there’s always a chance things can turn violent when tensions are high. Should things go south, take comfort in the knowledge that a company in Japan has introduced a robot ambulance service. It’s probably more accurate to compare it with roadside assistance, as the goal is to repair the robot on-site. That said, if the fault is more serious, they can bring the damaged bot back to HQ. Of course, the major difference between this program and a traditional ambulance service is that they’ll be able to bring along a spare robot that can take over the patient’s job while repairs are being made. Should anyone start doing that for humans, expect a few more protests.

Speaking of repairs, [Boone Ashworth] at WIRED recently wrote up an interesting hands-on experience he had with John Deere’s AI-driven DIY repair service at the company’s corporate headquarters. Armed with a laptop and tasked with fixing the error message showing on a ~$120,000 USD tractor, he was able to follow the instructions provided by the software to identify a sensor that had been unplugged. Reconnecting the sensor fixed the error message and elicited applause from the Deere reps who presumably had carefully unplugged the sensor in the first place for the purposes of the demonstration.

If that doesn’t strike you as a particularly impressive display for a subscription service which starts at $195 a year for each individual machine, you aren’t alone. When Boone reported his experience to critics of Deere’s repairability track record, it was met with literal laughter. You don’t have to have worked in the fields to know that a sensor becoming unplugged ranks pretty low on the list of potential problems you might face in the middle of a harvest.

We can certainly understand why Deere wouldn’t ask journalists to fix a blown clutch or a leaky hydraulic cylinder for the purposes of a media demo. Even so, they could surely have come up with something a bit more challenging if their goal was to convince customers to log into their repair service — something the company claims only about a thousand users do each day.

Finally, this one leans more heavily into the “arts and crafts” than we’d usually cover here on Hackaday, but [Terence Eden]’s Collection of Imaginary Software is too cool not to get a mention.

The idea is simple enough: make up fake disk labels for a bunch of fictional pieces of software (think the games David Lightman was trying to get his hands on in WarGames), stick them on some of the old 3.5 floppies we know you have hiding in a box somewhere, and put them in a frame.

As we’ve talked about in the past, many of us in the hacker and maker community were inspired by nerds in the media. This project strikes us as a fantastic way to show off just which examples you resonated with personally, and if any readers come up with something similar to adorn the walls of their basement, we’d love to see it.

See something interesting that you think would be a good fit for our weekly Links column? Drop us a line; we’d love to hear about it.

It is a classic Hackaday situation. You have an Egret GT E-scooter. It has a screen that shows the usual dash stats, but that led to an annoyance. You could accidentally enter firmware update mode and, from there, enter operational mode without the security PIN. [Ben] couldn’t let that stand, so he reverse-engineered the protocol and rewrote the firmware in Rust. As he put it, “… because I have to break… everything I own…” We get it.

The mobile app was useful for some basic info, since sniffing Bluetooth is fairly easy and analyzing mobile code is, more or less, straightforward. Analysis revealed some data that doesn’t show on the display and that several things are sent back to home base tagged with the scooter’s unique ID — another reason to gut the existing firmware.

Internally, the scooter uses the CAN Bus, so out came the oscilloscope and a homebrew CAN decoder.  Surprisingly, the CAN bus is accessible on the USB-C port’s data pins. Officially, the port is only for charging phones, so you have to wonder what your phone makes of the alien signals on the data pins when it is charging.

Firmware updates actually come in at least three flavors: display, input panel, and main controller. Reverse engineering the firmware update process was crucial to installing the new firmware.

If you own a similar scooter, this post is a goldmine. If you don’t, it is still a very detailed breakdown of a reverse-engineering workflow, and you can apply many of the tools and techniques to your next project.

Of course, another option is to just keep the scooter and replace the brains. If you want to learn more about reverse engineering, there are literally dozens of Hackaday posts to help you get started.