Hackaday Podcast 154: A Good Enough CNC, Stepper Motors Unrolled, Smart Two-Wire LEDs, A Volcano Heard Around The World

Join Hackaday Editor-in-Chief Elliot Williams and Staff Writer Dan Maloney for this week’s podcast as we talk about Elliot’s “defection” to another podcast, the pros and cons of CNC builds, and making Nixie clocks better with more clicking. We’ll explore how citizen scientists are keeping a finger on the pulse of planet Earth, watch a 2D stepper go through its paces, and figure out how a minimalist addressable LED strip works. From solving a Rubik’s cube to answering the age-old question, “Does a watched pot boil?” — spoiler alert: if it’s well designed, yes — this episode has something for everyone.

Take a look at the links below if you want to follow along, and as always, tell us what you think about this episode in the comments!

Direct Download (Less than 60 MB)

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Floppy disks

Adafruit Hack Chat Helps You Copy That Floppy

You might think the era of the 3.5 inch “floppy” disk is over, and of course, you’d be right. But when has that ever stopped hackers before? Just because these disks are no longer being manufactured doesn’t mean you can’t find them, or that the appropriate drives aren’t readily available. In fact, as [Ladyada] explained during this week’s Floppy Interfacing Hack Chat with Adafruit, the ongoing chip shortages mean its often easier and cheaper to track down old hardware like this than it is modern microcontrollers and other high-tech components.

Hack Chat posterWhat awaits the brave hacker that picks up a box of random floppies and a dusty old drive at the local thrift store? More than you might expect. As the Hack Chat goes on, it becomes increasingly obvious that these quaint pieces of antiquated technology can be rather difficult to work with. For one thing there are more formats out there than you’ve probably considered, and maddeningly, not all drives are able to read all types (even if they say they do). That means a disk which might seem like a dud on one drive could work perfectly fine in another, which is why the team at Adafruit recommend having a few on hand if you want to maximize your chances of success.

Now here comes the tricky part: unless you happen to have a 1990s vintage computer laying around, getting these drives hooked up is decidedly non-trivial. Which is why Adafruit have been researching how to interface the drives with modern microcontrollers. This includes the Adafruit_Floppy project, which aims to port the well known Greaseweazle and FluxEngine firmwares to affordable MCUs like the Raspberry Pi Pico. There’s also been promising developments with bringing native floppy support to CircuitPython, which would make reading these disks as easy as writing a few lines of code.

But wait, surely this is a solved problem? Why not just pick up a cheap USB floppy drive from the A to Z online retailer we all love to hate? Unfortunately, these gadgets are something of a mixed bag. [Ladyada] pulls one apart on camera to show that what you’re actually getting with one of these units is a new old stock laptop floppy drive hooked up to a dodgy purpose-built chip that connects to the original 26-pin flex cable and offers up a USB interface. That would be great, if it wasn’t for the fact that the chip is exceedingly selective about what kind of disks it will read. If you’re only worried about bog standard IBM-formatted disks they can work in a pinch, but like they say, you get what you pay for.

So is it all just academic? Is there really any reason to use a floppy disk in 2022? The fine folks at Adafruit would argue that the skills necessary to read usable data out of a stream of magnetic flux changes may very well come in handy in unexpected ways down the road. But even if not, there’s at least one good reason to cultivate the technology required to reliably read from these once ubiquitous storage devices: archiving the data stored on these disks before they invariably succumb to so-called “bit rot” and are potentially lost to history.

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This Week In Security: Samba, Wormhole Crypto Heist, And A Bogus CVE

Samba has a very serious vulnerability, CVE-2021-44142, that was just patched in new releases 4.13.17, 4.14.12, and 4.15.5. Discovered by researchers at TrendMicro, this unauthenticated RCE bug weighs in at a CVSS 9.9. The saving grace is that it requires the fruit VFS module to be enabled, which is used to support MacOS client and server interop. If enabled, the default settings are vulnerable. Attacks haven’t been seen in the wild yet, but go ahead and get updated, as PoC code will likely drop soon.

Crypto Down the Wormhole

One notable selling point to cryptocurrencies and Web3 are smart contracts, little computer programs running directly on the blockchain that can move funds around very quickly, without intervention. It’s quickly becoming apparent that the glaring disadvantage is these are computer programs that can move money around very quickly, without intervention. This week there was another example of smart contracts at work, when an attacker stole $326 million worth of Ethereum via the Wormhole bridge. A cryptocurrency bridge is a service that exists as linked smart contracts on two different blockchains. These contracts let you put a currency in on one side, and take it out on the other, effectively transferring currency to a different blockchain. Helping us make sense of what went wrong is [Kelvin Fichter], also known appropriately as [smartcontracts].

When the bridge makes a transfer, tokens are deposited in the smart contract on one blockchain, and a transfer message is produced. This message is like a digital checking account check, which you take to the other side of the bridge to cash. The other end of the bridge verifies the signature on the “check”, and if everything matches, your funds show up. The problem is that one one side of the bridge, the verification routine could be replaced by a dummy routine, by the end user, and the code didn’t catch it.

It’s a hot check scam. The attacker created a spoofed transfer message, provided a bogus verification routine, and the bridge accepted it as genuine. The majority of the money was transferred back across the bridge, where other user’s valid tokens were being held, and the attacker walked away with 90,000 of those ETH tokens. Continue reading “This Week In Security: Samba, Wormhole Crypto Heist, And A Bogus CVE”

Retrotechtacular: Understanding The Strength Of Structural Shapes

Strength. Rigidity. Dependability. The ability to bear weight without buckling. These are all things that we look for when we build a mechanical structure. And in today’s Retrotechtacular we take a closer look at the answer to a question: “What’s in A Shape?”

As it turns out, quite a lot. In a wonderful film by the prolific Jam Handy Organization in the 1940’s, we take a scientific look at how shape affects the load bearing capacity of a beam. A single sided piece of metal, angle iron, C-channel, and boxed tubing all made of the same thickness metal are compared to see not just just how much load they can take, but also how they fail.

The concepts are then given practical application in things that we still deal with on a daily basis: Bridges, cars, aircraft, and buildings. Aircraft spars, bridge beams, car frames, and building girders all benefit from the engineering discussed in this time capsule of film.

None of the concepts in this video are suddenly out of date, because while our understanding of engineering has certainly progressed since this film was made, these basic concepts remain the same. As such, they will apply to any structural or mechanical devices that we make, be it 3d printed, CNC routed, welded, glued, vacuum formed, zip tied, duct taped, bailing wired, or hot glued.

Keep your eyes open for a wonderful sights and sounds of a rare Boeing 314 Clipper landing on water and a 1920’s Buffalo Springfield Steam Roller demonstrating how wonderful the film’s sponsor, Chevrolet, makes their automobile frames.

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Remoticon 2021 // Colin O’Flynn Zaps Chips (And They Talk)

One of the many fascinating fields that’s covered by Hackaday’s remit lies in the world of hardware security, working with physical electronic hardware to reveal inner secrets concealed in its firmware. Colin O’Flynn is the originator of the ChipWhisperer open-source analysis and fault injection board, and he is a master of the art of glitching chips. We were lucky enough to be able to welcome him to speak at last year’s Remoticon on-line conference, and now you can watch the video of his talk below the break. If you need to learn how to break RSA encryption with something like a disposable camera flash, this is the talk for you.

This talk is an introduction to signal sniffing and fault injection techniques. It’s well-presented and not presented as some unattainable wizardry, and as his power analysis demo shows a clearly different trace on the correct first letter of a password attack the viewer is left with an understanding of what’s going on rather than hoping for inspiration in a stream of the incomprehensible. The learning potential of being in full control of both instrument and target is evident, and continues as the talk moves onto fault injection with an introduction to power supply glitching as a technique to influence code execution.

Schematic of an EM injector built from a camera flash.
Schematic of an EM injector built from a camera flash.

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Know Audio: A Mess Of Cables

We’ve now spent several months in this series journeying through the world of audio, and along the way we’ve looked at the various parts of a Hi-Fi system from the speaker backwards to the source. It’s been an enjoyable ride full of technical detail and examining Hi-Fi myths in equal measure, but now it’s time to descend into one of the simplest yet most controversial areas of audio reproduction. Every audio component, whether digital or analogue, must be connected into whatever system it is part of, and this is the job of audio cables, sometimes referred to as interconnects. They are probably the single component most susceptible to tenuous claims about their performance, with audiophiles prepared to spend vast sums on cables claimed to deliver that extra bit of listening performance. Is there something in it, or are they all the same bits of wire with the expensive ones being a scam? Time to take a look.

What Makes A Nearly Good Cable

In a typical domestic audio system with digital and analogue signals you might expect to find two types of cable, electrical interconnects that could carry either analogue or digital signals, and optical ones for digital signals. We’re here to talk about the electrical cables here as they’re the ones used for analogue signals, so lets start with a little transmission line theory. Continue reading “Know Audio: A Mess Of Cables”

A pinout diagram of the new Pi 4, showing all the alternate interfaces available.

Did You Know That The Raspberry Pi 4 Has More SPI, I2C, UART Ports?

We’ve gotten used to the GPIO-available functions of Raspberry Pi computers remaining largely the same over the years, which is why it might have flown a little bit under the radar: the Raspberry Pi 4 has six SPI controllers, six I2C controllers, and six UARTs – all on its 40-pin header. You can’t make use of all of these at once, but with up to four different connections wired to a single pin you can carve out a pretty powerful combination of peripherals for your next robotics, automation or cat herding project.

The datasheet for these peripherals is pleasant to go through, with all the register maps nicely laid out – even if you don’t plan to work with the register mappings yourself, the maintainers of your preferred hardware enablement libraries will have an easier time! And, of course, these peripherals are present on the Compute Module 4, too. It might feel like such a deluge of interfaces is excessive, however, it lets you achieve some pretty cool stuff that wouldn’t be possible otherwise.

Having multiple I2C interfaces helps deal with various I2C-specific problems, such as address conflicts, throughput issues, and mixing devices that support different maximum speeds, which means you no longer need fancy mux chips to run five low-resolution Melexis thermal camera sensors at once. (Oh, and the I2C clock stretching bug has been fixed!) SPI interfaces are used for devices with high bandwidth, and with a few separate SPI ports, you could run multiple relatively high-resolution displays at once, No-Nixie Nixie clock style.

As for UARTs, the Raspberry Pi’s one-and-a-half UART interface has long been an issue in robotics and home automation applications. With a slew of devices like radio receivers/transmitters, LIDARs and resilient RS485 multi-drop interfaces available in UART form, it’s nice that you no longer have to sacrifice Bluetooth or a debug console to get some fancy sensors wired up to your robot’s brain. You can enable up to six UARTs. Continue reading “Did You Know That The Raspberry Pi 4 Has More SPI, I2C, UART Ports?”