Hackaday Podcast Episode 284: Laser Fault Injection, Console Hacks, And Too Much Audio

The summer doldrums are here, but that doesn’t mean that Elliot and Dan couldn’t sift through the week’s hack and find the real gems. It was an audio-rich week, with a nifty microsynth, music bounced off the moon, and everything you always wanted to know about Raspberry Pi audio but were afraid to ask. We looked into the mysteries of waveguides and found a math-free way to understand how they work, and looked at the way Mecanum wheels work in the most soothing way possible. We also each locked in on more classic hacks, Elliot with a look at a buffer overflow in Tony Hawks Pro Skater and Dan with fault injection user a low-(ish) cost laser setup. From Proxxon upgrades to an RC submarine to Arya’s portable router build, we’ve got plenty of material for your late summer listening pleasure.

Worried about attracting the Black Helicopters? Download the DRM-free MP3 and listen offline, just in case.

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Unusual Tool Gets An Unusual Repair

In today’s value-engineered world, getting a decade of service out of a cordless tool is pretty impressive. By that point you’ve probably gotten your original investment back, and if the tool gives up the ghost, well, that’s what the e-waste bin is for. Not everyone likes to give up so easily, though, which results in clever repairs like the one that brought this cordless driver back to life.

The Black & Decker “Gyrodriver,” an interesting tool that is controlled with a twist of the wrist rather than the push of a button, worked well for [Petteri Aimonen] right up until the main planetary gear train started slipping thanks to stripped teeth on the plastic ring gear. Careful measurements of one of the planetary gears to determine parameters like the pitch and pressure angle of the teeth, along with the tooth count on both the planet gear and the stripped ring.

Here, most of us would have just 3D printed a replacement ring gear, but [Petteri] went a different way. He mentally rolled the ring gear out, envisioning it as a rack gear. To fabricate it, he simply ran a 60° V-bit across a sheet of steel plate, creating 56 parallel grooves with the correct pitch. Wrapping the grooved sheet around a round form created the ring gear while simultaneously closing the angle between teeth enough to match the measured 55° tooth angle in the original. [Petteri] says he soldered the two ends together to form the ring; it looks more like a weld in the photos, but whatever it was, the driver worked well after the old plastic teeth were milled out and the new ring gear was glued in place.

We think this is a really clever way to make gears, which seems like it would work well for both internal and external teeth. There are other ways to do it, of course, but this is one tip we’ll file away for a rainy day.

Ryobi Battery Pack Gives Up Its Secrets Before Giving Up The Ghost

Remember when dead batteries were something you’d just toss in the trash? Those days are long gone, thankfully, and rechargeable battery packs have put powerful cordless tools in the palms of our hands. But when those battery packs go bad, replacing them becomes an expensive proposition. And that’s a great excuse to pop a pack open and see what’s happening inside.

The battery pack in question found its way to [Don]’s bench by blinking some error codes and refusing to charge. Popping it open, he found a surprisingly packed PCB on top of the lithium cells, presumably the battery management system judging by the part numbers on some of the chips. There are a lot of test points along with some tempting headers, including one that gave up some serial data when the battery’s test button was pressed. The data isn’t encrypted, but it is somewhat cryptic, and didn’t give [Don] much help. Moving on to the test points, [Don] was able to measure the voltage of each battery in the series string. He also identified test pads that disable individual cells, at least judging by the serial output, which could be diagnostically interesting.  [Don]’s reverse engineering work is now focused on the charge controller chip, which he’s looking at through its I2C port. He seems to have done quite a bit of work capturing output and trying to square it with the chip’s datasheet, but he’s having trouble decoding it.

This would be a great place for the Hackaday community to pitch in so he can perhaps get this battery unbricked. We have to admit feeling a wee bit responsible for this, since [Don] reports that it was our article on reverse engineering a cheap security camera that inspired him to dig into this, so we’d love to get him some help.

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Hackaday Links: August 11, 2024

“Please say it wasn’t a regex, please say it wasn’t a regex; aww, crap, it was a regex!” That seems to be the conclusion now that Crowdstrike has released a full root-cause analysis of its now-infamous Windows outage that took down 8 million machines with knock-on effects that reverberated through everything from healthcare to airlines. We’ve got to be honest and say that the twelve-page RCA was a little hard to get through, stuffed as it was with enough obfuscatory jargon to turn off even jargon lovers such as us. The gist, though, is that there was a “lack of a specific test for non-wildcard matching criteria,” which pretty much means someone screwed up a regular expression. Outside observers in the developer community have latched onto something more dire, though, as it appears the change that brought down so many machines was never tested on a single machine. That’s a little — OK, a lot — hard to believe, but it seems to be what Crowdstrike is saying. So go ahead and blame the regex, but it sure seems like there were deeper, darker forces at work here.

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Robot Arm Gives Kids The Roller Coaster Ride Of Their Lives

Unfortunately, [Dave Niewinski]’s kids are still too little to go on a real roller coaster. But they’re certainly big enough to be tossed around by this giant robot arm roller coaster simulator.

As to the question of why [Dave] has a Kuka KR 150 robot in his house, we prefer to leave that unasked and move forward. And apparently, this isn’t his first attempt at using the industrial robot as a motion simulator. That attempt revealed a few structural problems with the attachment between the rider’s chair and the robot’s wrist. After redesigning the frame with stouter metal and adding a small form-factor gaming PC and a curved monitor in front of the seat, [Dave] was ready to figure out how to make the arm simulate the motions of a roller coaster.

Now, if you ever thought the world would be a better place if only we had a roller coaster database complete with 4k 60 fps video captured from real coasters, you’re in luck. CoasterStats not only exists, but it also includes six-axis accelerometer data from real rides of coasters across Europe. That gave [Dave] the raw data he needed, but getting it translated into robot motions that simulate the feeling of the ride was a bit tricky. [Dave] goes into the physics of it all in the video below, but suffice it to say that the result is pretty cool.

More after the break.

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Laser Fault Injection On The Cheap

One can only imagine the wonders held within the crypto labs of organizations like the CIA or NSA. Therein must be machines of such sophistication that no electronic device could resist their attempts to defeat whatever security is baked into their silicon. Machines such as these no doubt bear price tags that only a no-questions-asked budget could support, making their techniques firmly out of reach of even the most ambitious home gamer.

That might be changing, though, with this $500 DIY laser fault injection setup. It comes to us from Finnish cybersecurity group [Fraktal], who have started a series of blog posts detailing how they built their open-source reverse-engineering rig. LFI is similar to other “glitching” attacks we’ve covered before, such as EMP fault injection, except that a laser shining directly on a silicon die is used to disrupt its operation rather than a burst of electromagnetic energy.

Since LFI requires shining the laser very precisely on nanometer-scale elements of a bare silicon die, nanopositioning is the biggest challenge. Rather than moving the device under attack, the [Fraktal] rig uses a modified laser galvanometer to scan an IR laser over the device. The galvo and the optical components are all easily available online, and they’ve started a repo to document the modifications needed and the code to tire everything together.

Of course, this technique requires the die in the device under study to be exposed, but [Fraktal] has made that pretty approachable too. They include instructions for milling away the epoxy from the lead-frame side of a chip, which is safer for the delicate structures etched into the top of the die. The laser can then shine directly through the die from the bottom. For “flip-chip” packages like BGAs, the same milling technique would be done from the top of the package. Either way, we can imagine a small CNC mill making the process safer and quicker, even though they seem to have done pretty well with a Dremel.

This looks like a fantastic reverse engineering tool, and we’re really looking forward to the rest of the story.
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Custom Pneumatic Cylinders Lock This Monitor Arm In Place

Few consumer-grade PCs are what you’d categorize as built to last. Most office-grade machines are as likely as not to give up the ghost after ingesting a few too many dust bunnies, and the average laptop can barely handle a few drops of latte and some muffin crumbs before croaking. Sticking a machine like that in the shop, especially a metal shop, is pretty much a death sentence.

And yet, computers are so useful in the shop that [Lucas] from “Cranktown City” built this neat industrial-strength monitor arm. His design will look familiar to anyone with a swing-arm mic or desk light, although his home-brew parallelogram arm is far sturdier thanks to the weight of the monitor and sheet-metal enclosure it supports. All that weight exceeded the ability of the springs [Lucas] had on hand, which led to the most interesting aspect of the build — a pair of pneumatic locks. These were turned from a scrap of aluminum rod and an old flange-head bolt; when air pressure is applied, the bolt is drawn into the cylinder, which locks the arm in place. To make it easy to unlock the arm, a pneumatic solenoid releases the pressure on the system at the touch of a button. The video below has a full explanation and demonstration.

While we love the idea, there are a few potential problems with the design. The first is that this isn’t a fail-safe design, since pressure is needed to keep the arm locked. That means if the air pressure drops the arm could unlock, letting gravity do a number on your nice monitor. Second is the more serious problem [Lucas] alluded to when he mentioned not wanting to be in the line of fire of those locks should something fail and the piston comes flying out under pressure. That could be fixed with a slight design change to retain the piston in the event of a catastrophic failure.

Problems aside, this was a great build, and we always love [Lucas]’ seat-of-the-pants engineering and his obvious gift for fabrication, of which his wall-mount plasma cutter is a perfect example.

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