The First Fitbit: Engineering And Industrial Design Lessons

August 9, 2024 by 7 Comments

It could happen to anyone of us: suddenly you got this inkling of an idea for a product that you think might just be pretty useful or even cool. Some of us then go on to develop a prototype and manage to get enough seed funding to begin the long and arduous journey to turn a sloppy prototype into a sleek, mass-produced product. This is basically the story of how the Fitbit came to be, with a pretty in-depth article by [Tekla S. Perry] in IEEE Spectrum covering the development process and the countless lessons learned along the way.

Of note was that this idea for an accelerometer-based activity tracker was not new in 2006, as a range of products already existed, from 1960s mechanical pedometers to 1990s medical sensors and the shoe-based Nike+ step tracker that used Apple’s iPod with a receiver. Where this idea for the Fitbit was new was that it’d target a wide audience with a small, convenient (and affordable) device. That also set them up for a major nightmare as the two inventors were plunged into the wonderfully terrifying world of industrial design and hardware development.

One thing that helped a lot was outsourcing what they could to skilled people and having solid seed funding. This left just many hardware decisions to make it as small as possible, as well as waterproof and low-power. The use of the ANT protocol instead of Bluetooth saved a lot of battery, but meant a base station was needed to connect to a PC. Making things waterproof required ultrasonic welding, but lack of antenna testing meant that a closed case had a massively reduced signal strength until a foam shim added some space. The external reset pin on the Fitbit for the base station had a low voltage on it all the time, which led to corrosion issues, and so on.

While much of this was standard development and testing  fun, the real challenge was in interpreting the data from the accelerometer. After all, what does a footstep look like to an accelerometer, and when is it just a pothole while travelling by car? Developing a good algorithm here took gathering a lot of real-world data using prototype hardware, which needed tweaking when later Fitbits moved from being clipped-on to being worn on the wrist. These days Fitbit is hardly the only game in town for fitness trackers, but you can definitely blame them for laying much of the groundwork for the countless options today.

500cc Of 4-Wheel Off-Road Fun

August 9, 2024 by 9 Comments

Who among us hasn’t at some point thought of building a little vehicle, and better still, a little off-road vehicle for a few high-octane rough-terrain adventures. [Made in Poland] has, and there he is in a new video with a little off-road buggy.

The video which we’ve paced below the break is quite long, and it’s one of those restful metalworking films in which we see the finished project take shape bit by bit. In this case the buggy has a tubular spaceframe, with front suspension taken from a scrap quad and a home-made solid rear axle. For power there’s a 500cc Suzuki two-cylinder motorcycle engine, with a very short chain drive from its gearbox to that axle. The controls are conventional up to a point, though we’d have probably gone for motorcycle style handlebars with a foot shift rather than the hand-grip shift.

The final machine is a pocket drift monster, and one we’d certainly like to have a play with. We’d prefer some roll-over protection and we wonder whether the handling might be improved were the engine sprung rather than being part of a huge swing-arm, but it doesn’t appear to interfere with the fun. If you fancy a go yourself it’s surprisingly affordable to make a small vehicle, just build a Hacky Racer.

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Hackaday Podcast Episode 283: Blinding Lasers, LEDs, And ETs

August 9, 2024 by 3 Comments

Hackaday Editors Elliot Williams and Al Williams reflect on the fact that, as humans, we have–at most–two eyes and no warp drives. While hacking might not be the world’s most dangerous hobby, you do get to work with dangerous voltages, temperatures, and frickin’ lasers. Light features prominently, as the guys talk about LED data interfaces, and detecting faster-than-light travel.

There’s also a USB sniffer, abusing hot glue, and some nostalgia topics ranging from CRT graphics to Apollo workstations (which have nothing directly to do with NASA). The can’t miss articles this week cover hacking you and how you make the red phone ring in the middle of a nuclear war.

Check out the links below if you want to follow along, and as always, tell us what you think about this episode in the comments!

As always, please download the file to archive in your doomsday bunker.

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Custom Pneumatic Cylinders Lock This Monitor Arm In Place

August 9, 2024 by 8 Comments

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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This Week In Security: GhostWrite, Localhost, And More

August 9, 2024 by 5 Comments

You may have heard some scary news about RISC-V CPUs. There’s good news, and bad news, and the whole thing is a bit of a cautionary tale. GhostWrite is a devastating vulnerability in a pair of T-Head XuanTie RISC-V CPUs. There are also unexploitable crashes in another T-Head CPU and the QEMU soft core implementation. These findings come courtesy of a group of researchers at the CISPA Helmholtz Center for Information Security in Germany. They took at look at RISC-V cores, and asked the question, do any of these instructions do anything unexpected? The answer, obviously, was “yes”.

Undocumented instructions have been around just about as long as we’ve had Van Neumann architecture processors. The RISC-V ISA put a lampshade on that reality, and calls them “vendor specific custom ISA extensions”. The problem is that vendors are in a hurry, have limited resources, and deadlines wait for no one. So sometimes things make it out the door with problems. To find those problems, CISPA researchers put together a test framework is called RISCVuzz, and it’s all about running each instruction on multiple chips, and watching for oddball behavior. They found a couple of “halt-and-catch-fire” problems, but the real winner (loser) is GhostWrite.

Now, this isn’t a speculative attack like Meltdown or Spectre. It’s more accurate to say that it’s a memory mapping problem. Memory mapping helps the OS keep programs independent of each other by giving them a simplified memory layout, doing the mapping from each program to physical memory in the background. There are instructions that operate using these virtual addresses, and one such is vs128.v. That instruction is intended to manipulate vectors, and use virtual addressing. The problem is that it actually operates directly on physical memory addresses, even bypassing cache. That’s not only memory, but also includes hardware with memory mapped addresses, entirely bypassing the OS. This instruction is the keys to the kingdom. Continue reading “This Week In Security: GhostWrite, Localhost, And More” →

Liquid (Reversibly) Solidifies At Room Temperature, Gets Used For 3D Prints

August 9, 2024 by 8 Comments

Researchers demonstrate sustainable 3D printing by using poly(N-isopropylacrylamide) solutions (PNIPAM), which speedily and reliably turn solid by undergoing a rapid phase change when in a salt solution.

This property has been used to 3D print objects by using a syringe tip as if it were a nozzle in a filament-based printer. As long as the liquid is being printed into contact with a salt solution, the result is a polymer that solidifies upon leaving the syringe.

What’s also interesting is that the process by which the PNIPAM-based solutions solidify is entirely reversible. Researchers demonstrate printing, breaking down, then re-printing, which is an awfully neat trick. Finally, by mixing different additives in with PNIPAM, one can obtain different properties in the final product. For example, researchers demonstrate making conductive prints by adding carbon nanotubes.

While we’ve seen the concept of printing with liquids by extruding them into a gel bath or similar approach, we haven’t seen a process that prides itself on being so reversible before. The research paper with all the details is available here, so check it out for all the details.

Fixing A Busted Fluke While Fighting A Wonky Schematic

August 9, 2024 by 16 Comments

Fluke meters have been around for a long, long time. Heck, we’ve got a Fluke 73 that we bought back in 1985 that’s still a daily driver. But just because they’ve been making them forever doesn’t mean they last forever, and getting a secondhand meter back in the game can be a challenge. That’s what [TheHWCave] learned with his revival of a wonky eBay Fluke 25, an effort that holds lessons for anyone in the used Fluke market.

Initial inspection of the meter showed encouragingly few signs of abuse, somewhat remarkable for something built for the military in the early 1980s. A working display allowed a few simple diagnostics revealing that the ammeter functions seemed to work, but not the voltmeter and ohmmeter functions. [TheHWCave]’s teardown revealed a solidly constructed unit with no obvious signs of damage or blown fuses. Thankfully, a service schematic was available online, albeit one with a frustrating lack of detail, confusing test point nomenclature, and contradictory component values.

Despite these hurdles, [TheHWCave] was able to locate the culprit: a bad fusible power resistor. Finding a direct replacement wasn’t easy given the vagaries of the schematic and the age of the instrument, but he managed to track down a close substitute cheap enough to buy in bulk. He searched through 40 units to find the one closest to the listed specs, which got the meter going again. Fixing the bent pin also gave the meter back its continuity beeper, always a mixed blessing.

If you’re in the market for a meter but can’t afford the Fluke name, picking up a busted meter and fixing it up like this might be one way to go. But are they really worth the premium? Well, kinda yes.

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