JTAG & SWD Debugging On The Pi Pico

[Surya Chilukuri] writes in to share JTAGprobe — a fork of the official Raspberry Pi debugprobe firmware that lets you use the low-cost microcontroller development board for JTAG and SWD debugging just by flashing the provided firmware image.

We’ve seen similar projects in the past, but they’ve required some additional code running on the computer to bridge the gap between the Pico and your debugging software of choice. But [Surya] says this project works out of the box with common tools such as OpenOCD and pyOCD.

As we’ve cautioned previously, remember that the Pi Pico is only a 3.3 V device. JTAG and SWD don’t have set voltages, so in the wild you could run into logic levels from 1.2 V all the way to 5.5 V. While being able to use a bare Pico as a debugger is a neat trick, adding in a level shifter would be a wise precaution.

Looking to get even more use out of those Pi Picos you’ve got in the parts bin? How about using it to sniff USB?

A Field Expedient Welder Only MacGyver Could Love

If you needed to weld something in a pinch, what’s the minimum complement of equipment you could get away with? In [Professor Bardal]’s case, it’s a couple of motorcycle batteries and a roll of flux-core wire, and not much else.

We suspect this one is going to elicit quite a few comments, not least by the welding fans who no doubt will be triggered by just about everything in the video below, especially by characterizing this as MIG welding; it’s FCAW, or flux-core arc welding. But it bears some superficial similarities to MIG, at least insofar as there’s a consumable wire electrode through which a high-current DC supply flows, creating enough heat to melt it and the base metal. In this case, the current is provided by a pair of 12-volt motorcycle batteries hooked together in series. There’s also a torch of sorts — a short length of copper capillary tubing with a 1-mm inside diameter clamped in the jaws of a stick welder stinger, or a pair of locking pliers if you’re really in a pinch. The torch is connected to the negative terminal on the battery with a jumper cable, and the positive terminal is connected to the workpiece.

To create the weld, a piece of 0.8-mm flux-core welding wire is threaded through the capillary and into the joint, and fed by hand as it’s consumed. It’s awkward and awful, but it works. Of course, there’s no control over amperage as there would be with a legit welding machine, which would make it hard to adapt this method to different materials. Weld quality appears poor, too. But we suspect that if you were in a position to need a welder like this, you wouldn’t really care about any of that.

Fabricobbled welding rigs seem to be [Professor Bardal]’s thing — witness this much more professional MIG welder, complete with a baking soda and vinegar shielding gas generator.

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Simple Hardware Store Hack Keeps Your PCBs Right Where You Want Them

Sometimes it’s the simplest hacks that make the biggest impact.

Take these DIY magnetic PCB vises for example. Sure, you can go out and buy purpose-built tools, but [Dylan Radcliffe] just made a trip to the hardware store for some nuts and bolts. He chose 3/8″-16 bolts, which would probably be around M10 for the rest of the world. The head of each bolt is ground flat so a ceramic disc magnet can be attached to it with CA glue, while the head of the bolt gets a plastic washer glued to it. Another plastic washer gets glued to a nut, which when threaded onto the bolt provides the light clamping force needed to hold a PCB. Make four of those and stick them to a steel plate with the magnets, and you can stop chasing your boards around the bench with a soldering iron.

As much as we like this idea — and we do; we’re heading to Home Depot to buy the needed parts this very evening — we can think of a few useful modifications. With a long bolt and two nuts rather than one, you could make a set of vises that are easily adjustable along the Z-axis. This could prove useful to those of us working under a microscope. Also, rather than making the bolts the magnetic part we bet you could lay down a flexible magnetic sheet, the kind you can feed into a printer to roll your own fridge magnets. We suspect that would hold the bolts firmly enough for most work while still allowing easy repositioning. We’d also favor flange nuts over plain hex nuts, to give a larger clamping area. We’d still include the plastic washers, though, or possibly switch to rubber ones.

There’s more than one way to skin this cat, of course, especially if you’ve got a Harbor Freight nearby and a well-stocked Lego bin.

Using The ESP8266 For Low-Cost Fault Injection

As a general concept, fault injection is a technique that studies how a system reacts to unusual or unexpected external forces. The idea is that, if you can trigger a glitch at the precise moment, you might be able to use that to your advantage in disabling security features or otherwise gaining further access to the device in question. In the hardware world, this could be achieved by fiddling with the power going into the device, or subjecting it to extreme temperatures.

We’ve covered voltage glitching attacks on these pages in the past, but most of the tools used are fairly expensive if you’re not doing this kind of thing professionally. Luckily for us, [Aditya Patil] has developed a fault injection tool that can run on a standard ESP8266 development board. Obviously it’s not as capable as a bespoke device costing hundreds of dollars, but if you just want to experiment with the concept, it’s a fantastic way to wrap your head around it all.

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IFixit Releases Command Line Docs For FixHub Iron

When we reviewed the iFixit FixHub back in September, one of the most interesting features of the portable soldering station was the command line interface that both the iron and the base station offered up once you connected to them via USB. While this feature wasn’t documented anywhere, it made a degree of a sense, as the devices used WebSerial to communicate with the browser. What was less clear at the time was whether or not the user was supposed to be fiddling with this interface, or if iFixit intended to lock it up in a future firmware update.

Thanks to a recent info dump on GitHub, it seems like we have our answer. In the repo, iFixit has provided documentation for each individual command on both the iron and base, including some background information and application notes for a few of the more esoteric functions. A handful of the commands are apparently disabled in the production version of the firmware, but there’s still plenty to poke around with.

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The Engineer Behind Mine Detection

According to [Joanna Goodrich]  in IEEE Spectrum, prior to World War II, soldiers who wanted to find land mines, simply poked at the ground with pointed sticks or bayonets. As you might expect, this wasn’t very safe or reliable. In 1941, a Polish signals officer, [Józef Stanislaw Kosacki], escaped to Britain and created an effective portable mine detector.

[Kosaci] was an electrical engineer trained at the Warsaw University of Technology. He had worked as a manager for the Polish National Telecommunication Institute. In 1937, the government tasked him with developing a machine that could detect unexploded grenades and shells. The machine was never deployed.

When Germany invaded Poland in 1939, [Kosacki] returned to military service (he had done a year of compulsory service earlier). He was captured and kept in a prison camp in Hungary. But he managed to escape in late 1939 and joined the Polish Army Corps in Britain, teaching Morse code to soldiers.

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Retrotechtacular: Soldering The Tek Way

For a lot of us, soldering just seems to come naturally. But if we’re being honest, none of us was born with a soldering iron in our hand — ouch! — and if we’re good at soldering now, it’s only thanks to good habits and long practice. But what if you’re a company that lives and dies by the quality of the solder joints your employees produce? How do you get them to embrace the dark art of soldering?

If you’re Tektronix in the late 1970s and early 1980s, the answer is simple: make in-depth training videos that teach people to solder the Tek way. The first video below, from 1977, is aimed at workers on the assembly line and as such concentrates mainly on the practical aspects of making solid solder joints on PCBs and mainly with through-hole components. The video does have a bit of theory on soldering chemistry and the difference between eutectic alloys and other tin-lead mixes, as well as a little about the proper use of silver-bearing solders. But most of the time is spent discussing the primary tool of the trade: the iron. Even though the film is dated and looks like a multi-generation dupe from VHS, it still has a lot of valuable tips; we’ve been soldering for decades and somehow never realized that cleaning a tip on a wet sponge is so effective because the sudden temperature change helps release oxides and burned flux. The more you know.

The second video below is aimed more at the Tek repair and rework technicians. It reiterates a lot of the material from the first video, but then veers off into repair-specific topics, like effective desoldering. Pro tip: Don’t use the “Heat and Shake” method of desoldering, and wear those safety glasses. There’s also a lot of detail on how to avoid damaging the PCB during repairs, and how to fix them if you do manage to lift a trace. They put a fair amount of emphasis on the importance of making repairs look good, especially with bodge wires, which should be placed on the back of the board so they’re not so obvious. It makes sense; Tek boards from the era are works of art, and you don’t want to mess with that.

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