Segger’s Awkward USB-C Issue With The J-Link Compact Debugger

October 1, 2025 by 34 Comments

Theoretically USB-C is a pretty nifty connector, but the reality is that it mostly provides many exciting new ways to make your device not work as expected. With the gory details covered by [Alvaro], the latest to join the party is Segger, with its J-Link BASE Compact MCU debugger displaying the same behavior which we saw back when the Raspberry Pi 4 was released in 2019. Back then so-called e-marked USB-C cables failed to power the SBC, much like how this particular J-Link unit refuses to power up when connected using one of those special USB-C cables.

We covered the issue in great detail back then, discussing how the CC1 and CC1 connections need to be wired up correctly with appropriate resistors in order for the USB-C supply – like a host PC – to provide power to the device. As [Alvaro] discovered through some investigation, this unit made basically the same mistake as the RPi 4B SBC before the corrected design. This involves wiring CC1 and CC2 together and as a result seeing the same <1 kOhm resistance on the active CC line, meaning that to the host device you just hooked up a USB-C audio dongle, which obviously shouldn’t be supplied with power.

Although it’s not easy to tell when this particular J-Link device was produced, the PCB notes its revision as v12.1, so presumably it’s not the first rodeo for this general design, and the product page already shows a different label than for the device that [Alvaro] has. It’s possible that it originally was sloppily converted from a previous micro-USB-powered design where CC lines do not exist and things Just Work™, but it’s still a pretty major oversight from what should be a reputable brand selling a device that costs €400 + VAT, rather than a reputable brand selling a <$100 SBC.

For any in the audience who have one of these USB-C-powered debuggers, does yours work with e-marked cables, and what is the revision and/or purchase date?

FLOSS Weekly Episode 849: Veilid: Be A Brick

October 1, 2025 by No comments

This week Jonathan talks with Brandon and TC about Veilid, the peer-to-peer networking framework that takes inspiration from Tor, and VeilidChat, the encrypted messenger built on top of it. What was the inspiration? How does it work, and what can you do with it? Listen to find out!

Continue reading “FLOSS Weekly Episode 849: Veilid: Be A Brick” →

Lost Techniques: Bond-out CPUs And In Circuit Emulation

October 1, 2025 by 17 Comments

These days, we take it for granted that you can connect a cheap piece of hardware to a microcontroller and have an amazing debugging experience. Stop the program. Examine memory and registers. You can see and usually change anything. There are only a handful of ways this is done on modern CPUs, and they all vary only by detail. But this wasn’t always the case. Getting that kind of view to an actual running system was an expensive proposition.

Today, you typically have some serial interface, often JTAG, and enough hardware in the IC to communicate with a host computer to reveal and change internal state, set breakpoints, and the rest. But that wasn’t always easy. In the bad old days, transistors were large and die were small. You couldn’t afford to add little debugging pins to each processor you produced.

This led to some very interesting workarounds. Of course, you could always run simulators on a larger computer. But that might not work in real time, and almost certainly didn’t have all the external things you wanted to connect to, unless you also simulated them. Continue reading “Lost Techniques: Bond-out CPUs And In Circuit Emulation” →

Building An Open Source Point Of Sale System

October 1, 2025 by 21 Comments

[Mukesh Sankhla] has been tinkering in the world of Point of Sale systems of late. His latest creation is a simple, straightforward kiosk system, and he’s open sourced the design.

The Latte Panda MU single-board computer is at the heart of the build, handling primary duties and communicating with the outside world. It’s hooked up to a touchscreen display which shows the various items available for purchase. As an x86 system, the Latte Panda runs Windows 11, along with a simple kiosk software package written in Python. The software uses Google Firebase as a database backend. There’s also an Xiao ESP32 S3 microcontroller in the mix, serving as an interface between the Latte Panda and the thermal printer which is charged with printing receipts.

It’s worth noting that this is just a point-of-sale system; it executes orders, but doesn’t directly deliver or vend anything. With that said, since it’s all open-source, there’s nothing stopping you from upgrading this project further.

We’ve featured other interesting point-of-sale systems before; particularly interesting was the San Francisco restaurant that was completely automated with no human interaction involved Continue reading “Building An Open Source Point Of Sale System” →

The Hottest Spark Plugs Were Actually Radioactive

October 1, 2025 by 57 Comments

In the middle of the 20th century, the atom was all the rage. Radiation was the shiny new solution to everything while being similarly poorly understood by the general public and a great deal of those working with it.

Against this backdrop, Firestone Tire and Rubber Company decided to sprinkle some radioactive magic into spark plugs. There was some science behind the silliness, but it turns out there are a number of good reasons we’re not using nuke plugs under the hood of cars to this day.

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An FPGA-Based Mechanical Keyboard

October 1, 2025 by 15 Comments

You can buy all kinds of keyboards these days, from basic big-brand stuff to obscure mechanical delicacies from small-time builders. Or, you can go the maker route, and build your own. That’s precisely what [Lambert Sartory] did with their Clavier build.

This build goes a bit of a different route to many other DIY keyboards out there, in that [Lambert] was keen to build it around an FPGA instead of an off-the-shelf microcontroller. To that end, the entire USB HID stack was implemented in VHDL on a Lattice ECP5 chip. It was a heavy-duty way to go, but it makes the keyboard quite unique compared to those that just rely on existing HID libraries to do the job. This onboard hardware also allowed [Lambert] to include JTAG, SPI, I2C, and UART interfaces right on the keyboard, as well as a USB hub for good measure.

As for the mechanical design, it’s a full-size 105-key ISO keyboard with one bonus key for good measure. That’s the coffee key, which either locks the attached computer when you’re going for a break, or resets the FPGA with a long press just in case it’s necessary. It’s built with Cherry MX compatible switches, has N-key rollover capability, and a mighty 1000 Hz polling rate. If you can exceed that by hand, you’re some sort of superhuman.

The great thing about building your own keyboard is you can put in whatever features you desire. If you’re whipping up your own neat interface devices, don’t hesitate to let us know!

Porting A Fortran Flight Simulator To Unity3D

October 1, 2025 by 8 Comments

There’s an old saying (paraphrasing a quote attributed to Hoare): “I don’t know what language scientists will use in the future, but I know it will be called Fortran.” The truth is, there is a ton of very sophisticated code in Fortran, and if you want to do something more modern, it is often easier to borrow it than to reinvent the wheel. When [Valgriz] picked up a textbook on aircraft simulation, he noted that it had an F-16 simulation in it. In Fortran. The challenge? Port it to Unity3D.

If you have a gamepad, you can try the result. However, the real payoff is the blog posts describing what he did. They go back to 2021, although the most recent was a few months ago, and they cover the entire process in great detail. You can also find the code on GitHub. If you are interested in flight simulation, flying, Fortran, or Unity3D, you’ll want to settle in and read all four posts. That will take some time.

Continue reading “Porting A Fortran Flight Simulator To Unity3D” →