Author: Aaron Beckendorf

27 Articles

A Prunt 3D printer control board is shown mounted in a 3D printer, just behind a power supply, in the center of the image.

Keeping Snap And Crackle Under Control With Prunt Printer Firmware

June 18, 2025 by 17 Comments

For quite some time now, Marlin has been the firmware of choice for any kind of custom 3D printer, with only Klipper offering some serious competition in the open-source world. [Liam Powell] aims to introduce some more variety with the development of Prunt, a 3D printer control board and firmware stack.

Smooth motion control is Prunt’s biggest advantage: Klipper and Marlin use trapezoidal (three-phase) motion profiles, which aim for acceleration changes with physically impossible rapidity, leading to vibrations and ringing on prints. By contrast, Prunt uses a more physically realistic 31-phase motion profile. This lets the user independently adjust velocity, acceleration, jerk, snap, and crackle (the increasingly higher-order derivatives of position with respect to time) to reduce vibration and create smoother prints. To avoid sharp accelerations, Prunt can also turn corners into 15-degree Bézier curves.

The focus on smooth motion isn’t just a software feature; the Prunt control board uses hardware timers to control step generation, rather than the CPU. This avoids the timing issues which Klipper sometimes faces, and avoids slowing other parts of the program down. The board also seems to have a particular focus on avoiding electrical damage. It can detect short circuits in the heaters, thermistors, fans, and endstops, and can cut power and give the user a warning when one occurs. If the board somehow experiences a serious electrical fault, the USB port is isolated to prevent damage to the host computer. The firmware’s source is available on GitHub.

If you’re more interested in well-established programs, we’ve given a quick introduction to Klipper in the past. We’ve also seen people develop their own firmware for the Bambu Lab X1.

Rhapsody OS is shown in its boot sequence on a monitor; the edge of the motherboard running it is just visible in the right side of the image.

Bringing An Obscure Apple Operating System To Modern Hardware

June 16, 2025 by 17 Comments

During Apple’s late-90s struggles with profitability, it made a few overtures toward licensing its software to other computer manufacturers, while at the same time trying to modernize its operating system, which was threatening to slip behind Windows. While Apple eventually scrapped their licensing plans, an interesting product of the situation was Rhapsody OS. Although Apple was still building PowerPC computers, Rhapsody also had compatibility with Intel processors, which [Omores] put to good use by running it on a relatively modern i7-3770 CPU.

[Omores] selected a Gigabyte GA-Z68A-D3-B3 motherboard because it supports IDE emulation for SATA drives, a protocol which Rhapsody requires. The operating system installer needs to run from two floppy disks, one for boot and one for drivers. The Gigabyte motherboard doesn’t support a floppy disk drive, so [Omores] used an older Asus P5E motherboard with a floppy drive to install Rhapsody onto an SSD, then transferred the SSD to the Gigabyte board. The installation initially had a kernel panic during installation caused by finding too much memory available. Limiting the physical RAM available to the OS by setting the maxmem value solved this issue.

After this, the graphical installation went fairly smoothly. A serial mouse was essential here, since Rhapsody doesn’t support USB. It detected the video card immediately, and eventually worked with one of [Omores]’s ethernet cards. [Omores] also took a brief look at Rhapsody’s interface. By default, there were no graphical programs for web browsing, decompressing files, or installing programs, so some command line work was necessary to install applications. Of course, the highlight of the video was the installation of a Doom port (RhapsoDoom).

This isn’t the first obscure Apple operating system we’ve seen; some of them have even involved updates to Apple’s original releases. We’ve also seen people build Apple hardware.

Thanks to [Stephen Walters] for the tip!

A coiled black USB-C to USB-C cable is shown on a white background.

An Open-Source Justification For USB Cable Paranoia

June 16, 2025 by 35 Comments

Most people know that they shouldn’t plug strange flash drives into their computers, but what about a USB cable? A cable doesn’t immediately register as an active electronic device to most people, but it’s entirely possible to hide a small, malicious microcontroller inside the shell of one of the plugs. [Joel Serna Moreno] and some collaborators have done just that with their Evil Crow Cable-Wind.

This cable comes in two variants: one USB-A to USB-C, and one with USB-C to USB-C. A tiny circuit board containing an ESP32-S3 hides inside a USB-C plug on each cable, and can carry out a keystroke injection attack. The cable’s firmware is open-source, and has an impressive set of features: a payload syntax checker, payload autocompletion, OS detection, and the ability to impersonate the USB device of your choice.

The cable provides a control interface over WiFi, and it’s possible to edit and deploy live payloads without physical access to the cable (this is where the syntax checker should be particularly useful). The firmware also provides a remote shell for computers without a network connection; the cable opens a shell on the target computer which routes commands and responses through the cable’s WiFi connection (demonstrated in the video below).

The main advantage of the Evil Crow Cable Wind is its price: only about $25, at which point you can afford to lose a few during deployment. We’ve previously seen a malicious cable once before. Of course, these attacks aren’t limited to cables and USB drives; we’ve seen them in USB-C docks, in a gaming mouse, and the fear of them in fans.

Thanks to [rustysun9] for the tip!

A black PCB is shown, with an Arduino Nano mounted in the bottom left corner. The rest of the space on the PCB is used up by ten DIP integrated circuits and a few resistors and diodes. Several black and red wires connect different parts of the PCB.

Meowsic Keyboard MIDI Adapter Aims For Purrfection

June 14, 2025 by 3 Comments

Both small children and cats have a certain tendency to make loud noises at inopportune times, but what if there were a way to combine these auditory effects? This seems to have been the reasoning behind the creation of the Meowsic keyboard, a children’s keyboard that renders notes as cats’ meows. [Steve Gilissen], an appreciator of unusual electronic instruments, discovered that while there had been projects that turned the Meowsic keyboard into a MIDI output device, no one had yet added MIDI input to it, which of course spurred the creation of his Meowsic MIDI adapter.

The switches in the keys of the original keyboard form a matrix of rows and columns, so that creating a connection between a particular row and column plays a certain note. [Steve]’s plan was to have a microcontroller read MIDI input, then connect the appropriate row and column to play the desired note. The first step was to use a small length of wire to connect rows and columns, thus manually mapping connections to notes. After this tedious step, he designed a PCB that hosts an Arduino Nano to accept input, two MCP23017 GPIO expanders to give it enough outputs, and CD4066BE CMOS switches to trigger the connections.
Continue reading “Meowsic Keyboard MIDI Adapter Aims For Purrfection” →

A clock face is shown consisting of two rings of plastic, with backlighting behind one of the rings. There is red light at the one o’clock position, and blue light at the nine-thirty position. A black plastic arm is pointing to the three-thirty position.

A Concentric Clock With Multiple Modes

June 14, 2025 by No comments

Most of us spend our lives within reach of a device that provides a clock, stopwatch, and a timer – you’re almost certainly reading this article on such a device – but there are fewer options if you want a screen-free clock. [Michael Suguitan]’s TOKIDOKI rectifies this situation by combining those three functions into a single, physical, analog clock face.

TOKIDOKI displays time by lighting the appropriate segments of two concentric rings of colored LEDs (Adafruit Neopixel rings); the inner ring indicates hours, while the outer ring displays minutes. There is one clock hand, and while it does indicate the passage of time in some situations, its main function is as a dial to control the clock’s different functions. The hand is connected to a Dynamixel XL-330 servo motor, which also serves as a position sensor. Winding the dial clockwise starts a countdown timer, with each successive full rotation switching to a larger unit of time (a fun/unsettling feature is that the largest chronometric unit is the user’s expected lifetime: 84 years). Winding counterclockwise either starts a stopwatch or sets an alarm, depending on how many full rotations you make.

A Raspberry Pi Pico running some MicroPython firmware manages the device and gets the current time from a local network. To soften the light’s quality, the LED rings are pointed backwards to provide back-lighting off of a recessed surface. The entire device is powered by USB-C, and is enclosed in a 3D-printed housing.

This project was designed as an experiment in minimal interfaces, and it certainly achieved that goal, though we imagine that it takes a bit of time to get used to using this clock. We always enjoy seeing innovative clocks here, from digital to analogue, and those that split the difference. Continue reading “A Concentric Clock With Multiple Modes” →

A circuit board is shown on a white background. It has a USB-A port on the front side, and a coiled wire antenna extending from another circuit board mounted above the first one.

A Remote-Controlled USB Rubber Ducky Clone

June 13, 2025 by 17 Comments

Despite the repeated warnings of system administrators, IT personnel, and anyone moderately aware of operational security, there are still quite a few people who will gladly plug a mysterious flash drive into their computers to see what’s on it. Devices which take advantage of this well-known behavioral vulnerability have a long history, the most famous of which is Hak5’s USB Rubber Ducky. That emulates a USB input device to rapidly execute attacker-defined commands on the target computer.

The main disadvantage of these keystroke injection attacks, from the attacker’s point of view, is that they’re not particularly subtle. It’s usually fairly obvious when something starts typing thousands of words per minute on your computer, and the victim’s next move is probably a call to IT. This is where [Krzysztof Witek]’s open-source Rubber Ducky clone has an advantage: it uses a signal detected by a SYN480R1 RF receiver to trigger the deployment of its payload. This does require the penetration tester who uses this to be on the site of the attack, but unlike with an always-on or timer-delayed Rubber Ducky, the attacker can trigger the payload when the victim is distracted or away from the computer.

This project is based around the ATmega16U2, and runs a firmware based on microdevt, a C framework for embedded development which [Krzysztof] also wrote. The project includes a custom compiler for a reduced form of Hak5’s payload programming language, so at least some of the available DuckyScript programs should be compatible with this. All of the project’s files are available on GitHub.

Perhaps due to the simplicity of the underlying concept, we’ve seen a few open source implementations of malicious input devices. One was even built into a USB cable.

The green CRT display of a scanning-electron microscope is shown, displaying small particles.

DIY Calibration Target For Electron Microscopes

June 12, 2025 by 3 Comments

It’s a problem that few of us will ever face, but if you ever have to calibrate your scanning electron microscope, you’ll need a resolution target with a high contrast under an electron beam. This requires an extremely small pattern of alternating high and low-density materials, which [ProjectsInFlight] created in his latest video by depositing gold nanoparticles on a silicon slide.

[ProjectsInFlight]’s scanning electron microscope came from a lab that discarded it as nonfunctional, and as we’ve seen before, he’s since been getting it back into working condition. When it was new, it could magnify 200,000 times and resolve features of 5.5 nm, and a resolution target with a range of feature sizes would indicate how high a magnification the microscope could still reach. [ProjectsInFlight] could also use the target to make before-and-after comparisons for his repairs, and to properly adjust the electron beam.

Since it’s easy to get very flat silicon wafers, [ProjectsInFlight] settled on these as the low-density portion of the target, and deposited a range of sizes of gold nanoparticles onto them as the high-density portion. To make the nanoparticles, he started by dissolving a small sample of gold in aqua regia to make chloroauric acid, then reduced this back to gold nanoparticles using sodium citrate. This gave particles in the 50-100 nanometer range, but [ProjectsInFlight] also needed some larger particles. This proved troublesome for a while, until he learned that he needed to cool the reaction temperature solution to near freezing before making the nanoparticles.

Using these particles, [ProjectsInFlight] was able to tune the astigmatism settings on the microscope’s electron beam so that it could clearly resolve the larger particles, and just barely see the smaller particles – quite an achievement considering that they’re under 100 nanometers across!

Electron microscopes are still a pretty rare build, but not unheard-of. If you ever find one that’s broken, it could be a worthwhile investment.

Continue reading “DIY Calibration Target For Electron Microscopes” →