One Solution, Many Problems

May 21, 2022 by Elliot Williams 7 Comments

You might think you’re lucky when one of your problems has multiple solutions, and you get to pick and choose, but you’re even luckier when one solution has many problems! This week I stumbled on an old solution in a new place. The project was a fantastic old MIDI guitar build, the Tryndelka by [Aleksandr Goltsov]. And the old solution? Switch matrix diodes.

You see, [Aleksandr] is making an electric guitar where the strings are pulled up to a certain voltage and then make contact with metal frets. Each fret is cut into six pieces, so that the strings can be read out individually, and the microcontroller scans each string in succession to test if it’s pressed down or not. Done, right? Wrong! The problem comes when two or more strings are pressed at once — the electrical path from the string you want will travel through the closed switch on a string that you’re not scanning. The solution is a ton of diodes.

I learned this problem the hard way in wiring up a MAME cabinet, at about 3 A.M. the night before we were going to bring it to Shmoocon. We finally got the whole USB/button code working, so we played some celebratory rounds of Street Fighter. We eventually noticed that hitting one button, or even moving the joystick in a particular direction, would block some of the other buttons from working, or change their function entirely. Quick Internet search later, and we were hand soldering 64 diodes until dawn. Good times!

But the fact that switch matrices need diodes, and exactly why, is forevermore burned in my brain. It’s fun to see it pop up in all sorts of contexts, from DIY keyboards to MIDI guitars, to Charliplexing. (It’s the “D” in LED!) It’s one of the classics — a solution to many problems.

Who Is Thinking About Open Source Firmware?

May 14, 2022 by Elliot Williams 23 Comments

Yesterday, we ran a post on NVIDIA’s announcement of open-source drivers for some of its most recent video cards. And Hackaday being huge proponents of open-source software and hardware, you’d think we’d be pouring the champagne. But it’s trickier than that.

Part of the reason that they are able to publish a completely new, open-source driver is that the secrets that they’d like to keep have moved into the firmware. So is the system as a whole more or less open? Yeah, maybe both.

With a more open interface between the hardware and the operating system, the jobs of people porting the drivers to different architectures are going to be easier. Bugs that are in what is now the driver layer should get found and fixed faster. All of the usual open-source arguments apply. But at the same time, the system as a whole isn’t all that much more transparent. The irony about the new NVIDIA drivers is that we’ve been pushing them to be more open for decades, and they’ve responded by pushing their secrets off into firmware.

Secrets that move from software to firmware are still secrets, and even those among us who are the most staunch proponents of open source have closed hardware and firmware paths in our computers. Take the Intel Management Engine, a small computer inside your computer that’s running all the time — even while the computer is “off”. You’d like to audit the code for that? Sorry. And it’s not like it hasn’t had its fair share of security relevant bugs.

And the rabbit hole goes deeper, of course. No modern X86 chips actually run the X86 machine language instructions — instead they have a microcode interpreter that reads the machine language and interprets it to what the chip really speaks. This is tremendously handy because it means that chip vendors can work around silicon bugs by simple pushing out a firmware update. But this also means that your CPU is running a secret firmware layer at core. This layer is of course not without bugs, some of which can have security relevant implications.

This goes double for your smartphone, which is chock-full of multiple processors that work more or less together to get the job done. So while Android users live in a more open environment than their iOS brethren, when you start to look down at the firmware layer, everything is the same. The top layer of the OS is open, but it’s swimming on top of an ocean of binary blobs.

How relevant any of this is to you might depend on what you intend to do with the device. If you’re into open source because you like to hack on software, having open drivers is a fantastic resource. If you’re looking toward openness for the security guarantees it offers, well, you’re out of luck because you still have to trust the firmware blindly. And if you’re into open source because the bugs tend to be found quicker, it’s a mix — while the top level drivers are made more inspectable, other parts of the code are pushed deeper into obscurity. Maybe it’s time to start paying attention to open source firmware?

Theory, Practice, And Ducted Fans

May 10, 2022 by Elliot Williams 9 Comments

About a year ago, [Wyman’s Workshop] needed a fan. But not just a regular-old fan, no sir. A ducted fan. You know, those fancy fan designs where the stationary shroud is so close to the moving fan blades that there’s essentially no gap, and a huge gain in aerodynamic efficiency? At least in theory?

Well, in practice, you can watch how it turned out in this video. (Also embedded below.) If you’re more of a “how-to-build-it” type, you’ll want to check out his build video — there’s lots of gluing 3D prints and woodworking. But we’re just in it for the ducted fan data!

And that’s why we’re writing it up! [Wyman] made a nice thrust-testing rig that the fan can pull on to figure out how much force it put out. And the theory aimed at 652 g of thrust, which was roughly confirmed. And then you get to power: with a 500 watt motor, he ended up producing 47 watts. Spoiler: he’s overloading the motor, even though he used a fairly beefy bench grinder motor.

So he re-did the fan design, from scratch, to better match the motor. And it performed better than the theory said it would. A pleasant surprise, but it meant re-doing the theory, including the full volume of the fan blade, which finally brought theory and practice together. Which then lead him design a whole slew of fan blades and test them out against each other.

He ends the video with a teaser that he’ll show us the results from various inlet profiles and fan cones and such. But the video is a year old, so we’re not holding our breath. Still, if you’re at all interested in fan design, and aren’t afraid of high-school physics, it’s worth your time.

Don’t care about the advantages of ducted fans, but simply want to make your quad look totally awesome? Have we got the hack for you!

Continue reading “Theory, Practice, And Ducted Fans” →

Becky Stern, David Cranor, And A CT Scanner Vs The Oura Ring

May 10, 2022 by Elliot Williams 7 Comments

If you wonder how it’s possible to fit a fitness tracker into a ring, well, you’re not alone. [Becky Stern] sent one off to get CT scanned, went at it with a rotary tool, and then she made a video about it with [David Cranor]. (Video embedded below.)

While it’s super cool that you can do a teardown without tearing anything down these days — thanks to the CT scan — most of the analysis is done on a cut-up version of the thing through a normal stereo microscope. Still, the ability to then flip over to a 3D CT scan of the thing is nice.

We absolutely concur with [Becky] and [David] that it’s astounding how much was fit into very little space. Somewhere along the way, [David] muses that the electrical, mechanical, and software design teams must have all worked tightly together on this project to pull it off, and it shows. All along, there’s a nice running dialog on how you know what you’re looking at when tearing at a new device, and it’s nice to look over their shoulders.

Then there’s the bit where [Becky] shows you what a lithium-ion battery pack looks like when you cut it in half. She says it was already mostly discharged, and she didn’t burst into flames. But take it easy out there! (Also, make sure you take your hot xylene out on the patio.)

X-ray machines are of course just the coolest thing when doing a teardown. We’ve seen them used from fixing multimeters to simply looking at servo motors.

Continue reading “Becky Stern, David Cranor, And A CT Scanner Vs The Oura Ring” →

Will MiSTer Fool You Into Learning FPGAs?

May 9, 2022 by Elliot Williams 45 Comments

What’s the killer app for FPGAs? For some people, the allure is the ultra-high data throughput for parallelizable tasks, which can enable some pretty gnarly projects. But what if you’re just starting out? How about 1980s style video games?

The MiSTer FPGA project created a bit of FPGA hardware that makes it easy to build essentially any old school video game or computer platform. That’s a massive clean slate. Of course, you can simply download someone else’s Atari ST or Commodore 64 setup and load it up, but if you want to learn FPGAs while recreating old-school video game machines, you’re going to want to get your hands dirty.

[Mister Retro Wolf] started up a video series last winter (trailer embedded below) where he’s embarked on a project to recreate a classic video game machine from the ground up using the MiSTer FPGA platform. In particular, he’s going to recreate the Namco Tank Battalion arcade game, from the schematics, in Verilog.

This is literally building a 6502-based video game machine from scratch (in gateware), so if you’re interested in retrocomputing or FPGAs, you’ll have something to learn here. He’s gotten through the CPU, screen, tilemap graphics, and memory so far, but it’s not done yet. To follow along, get yourself some hardware and you can probably catch up.

We’ve covered the MiSTer FPGA project before, of course, because we think it’s cool. And if a video game arcade machine is going to be your gateway drug into the seedy world of programmable gates, then so be it.

Continue reading “Will MiSTer Fool You Into Learning FPGAs?” →

Learning Obsolete Technology

May 7, 2022 by Elliot Williams 33 Comments

Tom Nardi and I were talking about his trip to the Vintage Computer Festival on the podcast, and he admitted to not having been a retrocomputer aficionado before his first trip. But he ended up keying some binary machine code into some collection of archaic silicon, and he got it. In the same episode, the sound of the week was a Strowger switch — the old electromechanical “brain” of telephone switching centers of old. The sample I used was from Sam of Look Mum No Computer on YouTube, who got one for his museum and thinks it’s just awesome.

Why do people like this kind of old (obsolete?) tech? It’s certainly not because it’s overwhelmingly capable — the giant old switch is replaced easily by a stack of silicon, and don’t even get me started on the old blinkenlights computer that Tom was keying on. In both of these cases, the people are significantly younger than the tech they’re playing around with, so that rules out nostalgia. What’s left?

I think it’s that sometimes the older technology is more immediate, more understandable, more tangible, and that resonates with people. In a time when we all have wonder devices that can do anything, programmed in languages that are pleasant, using libraries that are nothing short of magical in terms of making difficult things easy, understanding how things work down to the ground is a rare commodity.

But it’s a strange position to find ourselves in, technologically, where there’s almost necessarily a trade-off between the usefulness and functionality of a device with the ability to understand fundamentally how it works.

2022 Hackaday Prize Enters Second Round: Reuse, Recycle, Revamp

May 5, 2022 by Elliot Williams 8 Comments

Ding! That’s the bell for the second challenge round of the 2022 Hackaday Prize. If your project reuses or recycles what would otherwise be waste materials, or helps you to do the same for further projects, we want to see it.

Hackers are often frugal folk — we’ll recycle parts for projects because it’s easier on the pocketbook when prototyping. But in these strangest of times, when we’ve seen $1 microcontrollers in such shortage that they fetch $57 apiece (if you can get the parts at all), making use of what you’ve got on hand can be an outright necessity. If this is going to become the new normal, it’s going to make sense that we automate it. There’s gold, literally and metaphorically, in busted PCBs. How are you going to get the most value out of our broken electronic waste in our post-apocalyptic near future? Have you built an unpick-and-unplace machine? We’d like to see it.

But electronic parts are a small fraction of your recyclable materials, and plastics might play a larger role. If you’re a 3D printerer, you’ve doubtless thought about recycling plastic bottles into filament. Or maybe you’d like to take some of the existing plastics that are thrust upon you by this modern world and give them a second life? This factory churning out paving stones by remelting plastic with sand is doing it on an industrial scale, but could this be useful for the home gamer? Precious Plastic has a number of inspirational ideas. Or maybe you just need an HDPE hammer?

Have you built a fancy can crusher, or a plastics sorter, or a recycling robot? Head on over to Hackaday.io, write it up, and enter it into the Prize!

Basically any project that helps you recycle or reuse the material around you is fair game here. (But note that if you’ve got epic repair hacks, you’ll want to enter them in the upcoming Round Three: Hack it Back.) This round runs until June 12th and there are ten $500 awards up for grabs, so get hacking!