Bit-Banging The USB-PD Protocol

January 10, 2025 by Bryan Cockfield 14 Comments

For one-off projects, adding a few integrated circuits to a PCB is not too big of a deal. The price of transistors is extremely low thanks to Moore and his laws, so we’re fairly free to throw chips around like peanuts. But for extremely space-constrained projects, huge production runs, or for engineering challenges, every bit of PCB real estate counts. [g3gg0] falls into the latter group, and this project aims to remove the dedicated USB-PD module from a lighting project and instead bit-bang the protocol with the ESP32 already on the board.

The modern USB power delivery (PD) protocol isn’t quite as simple as older USB ports that simply present a 5V source to whatever plugs itself into the port. But with the added complexity we get a lot more capability including different voltages and greater power handling capabilities. The first step with the PD protocol is to communicate with a power source, which requires a 1.2V 600kHz signal. Just generating the signal is challenging enough, but the data encoding for USB requires level changes to encode bits rather than voltage levels directly. With that handled, the program can then move on to encoding packets and sending them out over the bus.

After everything is said and done, [g3gg0] has a piece of software that lets the ESP32 request voltages from a power supply, sniff and log PD communication, and inject commands with vendor defined messages (VDM), all without needing to use something like a CH224K chip which would normally offload the USB-PD tasks. For anyone looking to save PCB space for whatever reason, this could be a valuable starting point. To see some more capabilities of the protocol, check out this USB-PD power supply that can deliver 2 kW.

Retrotechtacular: Soldering The Tek Way

January 9, 2025 by Dan Maloney 40 Comments

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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Perfecting 20 Minute PCBs With Laser

January 5, 2025 by Al Williams 41 Comments

Normally, you have a choice with PCB prototypes: fast or cheap. [Stephen Hawes] has been trying fiber lasers to create PCBs. He’s learned a lot which he shares in the video below. Very good-looking singled-sided boards take just a few minutes. Fiber lasers are not cheap but they are within range for well-off hackers and certainly possible for a well-funded hackerspace.

One thing that’s important is to use FR1 phenolic substrate instead of the more common FR4. FR4 uses epoxy which will probably produce some toxic fumes under the laser.

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Blast Away The Flux — With Brake Cleaner?

December 26, 2024 by Dan Maloney 75 Comments

Can you use brake cleaner for flux removal on PCBs? According to [Half Burnt Toast], yes you can. But should you? Well, that’s another matter.

In our experience, flux removal seems to be far more difficult than it should be. We’ve seen plenty of examples of a tiny drop of isopropyl alcohol and a bit of light agitation with a cotton swab being more than enough to loosen up even the nastiest baked-on flux. If we do the same thing, all we get is a gummy mess embedded with cotton fibers smeared all over the board. We might be doing something wrong, or perhaps using the wrong flux, but every time we get those results, we have to admit toying with the idea of more extreme measures.

The LED bar graphs were not a fan of the brake cleaner.

[Toast] went there, busting out a fresh can of brake cleaner and hosing down some of the crustier examples in his collection. The heady dry-cleaner aroma of perchloroethylene was soon in the air, and the powerful solvent along with the high-pressure aerosol blast seemed to work wonders on flux. The board substrate, the resist layer, and the silkscreen all seemed unaffected by the solvent, and the components were left mostly intact; one LED bar graph display did a little melty, though.

So it works, but you might want to think twice about it. The chlorinated formula he used for these tests is pretty strong stuff, and isn’t even available in a lot of places. Ironically, the more environmentally friendly stuff seems like it would be even worse, loaded as it is with acetone and toluene. Whichever formula you choose, proceed with caution and use the appropriate PPE.

What even is flux, and what makes it so hard to clean? Making your own might provide some answers.

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Rudolph’s Sleigh On A North Pole PCB

December 20, 2024 by Heidi Ulrich 18 Comments

Each Christmas, [Adam Anderson], [Daniel Quach], [Johan Wheeler], and [Gustav Abrahamsson] (going by ‘the Janky Jingle Crew’)—set themselves the challenge of outdoing their previous creations. Last year’s CH32 Fireplace brought an animated LED fire to life with CH32V003 microcontrollers.

This year, they’ve gone a step further with the North Pole Circuit, a holiday project that combines magnetic propulsion, festive decorations, and a bit of engineering flair. Inspired by a miniature speedway based on Friedrich Gauss’ findings, the North Pole Circuit includes sleighs and reindeer that glide along a custom PCB track, a glowing village with flickering lights, and a buzzer to play Christmas tunes.

The propulsion system works using the Lorentz force, where vertical magnets interact with PCB traces to produce motion. A two-phase design, similar to a stepper motor, ensures smooth operation, while guard rails maintain stability on curves. A separate CH32V003 handles lighting and synchronized jingles, creating a cohesive festive display. As we mentioned in the article on their last year’s creation, going from a one-off to a full batch will make one rethink the joy of repetitive production. Consider the recipients of these tiny Christmas cards quite the lucky ones. We deem this little gift a keeper to put on display when Christmas rolls around again.

This annual tradition highlights the Crew’s knack for combining fun and engineering. Curious about the details or feeling inspired to create your own? Explore the full details and files on their GitHub.

Hackaday Links: November 17, 2024

November 17, 2024 by Dan Maloney 18 Comments

A couple of weeks back, we covered an interesting method for prototyping PCBs using a modified CNC mill to 3D print solder onto a blank FR4 substrate. The video showing this process generated a lot of interest and no fewer than 20 tips to the Hackaday tips line, which continued to come in dribs and drabs this week. In a world where low-cost, fast-turn PCB fabs exist, the amount of effort that went into this method makes little sense, and readers certainly made that known in the comments section. Given that the blokes who pulled this off are gearheads with no hobby electronics background, it kind of made their approach a little more understandable, but it still left a ton of practical questions about how they pulled it off. And now a new video from the aptly named Bad Obsession Motorsports attempts to explain what went on behind the scenes.

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Rapid Prototyping PCBs With The Circuit Graver

November 6, 2024 by Dave Rowntree 27 Comments

Walking around the alley at Hackaday Supercon 2024, we noticed an interesting project was getting quite a bit of attention, so we got nearer for a close-up. The ‘Circuit Graver’ by [Zach Fredin] is an unconventional PCB milling machine, utilizing many 3D printed parts, the familiar bed-slinger style Cartesian bot layout and a unique cutting head. The cutting tool, which started life as a tungsten carbide lathe tool, is held on a rotary (‘R’) axis but can also move vertically via a flexure-loaded carriage driven by a 13 kg servo motor.

The stocky flexure took a lot of iteration, as the build logs will show. Despite a wild goose chase attempting to measure the cutting force, a complete machine solution was found by simply making everything stiff enough to prevent the tool from chattering across the surface of the FR4 blank. Controlling and maintaining the rake angle was a critical parameter here. [Zach] actually took an additional step, which we likely wouldn’t have thought of, to have some copper blanks pre-fabricated to the required size and finished with an ENIG coating. It’s definitely a smart move!

To allow the production of PCB-class feature sizes compatible with a traditional PCB router, the cutting tool was sharpened to a much smaller point than would be used in a lathe using a stone. This reduced the point size sufficiently to allow feature sizes down to 4 mils, or at least that’s what initial characterization implied was viable. As you can see from the build logs, [Zach] has achieved a repeatable enough process to allow building a simple circuit using an SMT 74HC595 and some 0402 LEDs to create an SAO for this year’s Supercon badge. Neat stuff!

We see a fair few PCB mills, some 3D printed, and some not. Here’s a nice one that fits in that former category. Milling PCBs is quite a good solution for the rapid prototyping of electronics. Here’s a guide about that.

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