A Linux Business Card You Can Build

July 14, 2022 by 22 Comments

It is a sign of the times that one of [Dmitry’s] design criteria for his new Linux on a business card is to use parts you can actually find during the current component shortage. The resulting board uses a ATSAMD21 chip and emulates a MIPS machine in order to boot Linux.

We like that in addition to the build details, [Dmitry] outlines a lot of the reasons for his decisions. There’s also a a fair amount of detail about how the whole system actually works. For example, by using a 0.8 mm PCB, the board can accept a USB-C cable with no additional connector. There is also a great explanation of the MIPS MMU and don’t forget that MIPS begat RISC-V, so many of the MIPS core details will apply to RISC-V as well (but not the MMU).  You’ll also find some critiques of the ATSAMD21’s DMA system. It seems to save chip real estate, the DMA system stores configuration data in user memory which it has to load and unload every time you switch channels.

By the end of the post you get the feeling this may be [Dimitry]’s last ATSAMD21 project. But we have to admit, it seems to have come out great. This isn’t the first business card Linux build we’ve seen. This one sure reminded us of a MIDI controller card we once saw.

Now Even Your Business Card Can Run Linux

December 24, 2019 by 50 Comments

It takes a lot of work to get a functional PCB business card that’s thin, cheap, and robust enough to be practical. If you can even blink a few LEDs on the thing and still hand them out with a straight face, you’ve done pretty well for yourself. So you can imagine our surprise when [George Hilliard] wrote in to tell us about his $3 business card computer that boots into a functioning Linux environment. If this were a bit closer to April, we might have figured it was just a joke…

Of course it helps that, as an embedded systems engineer, [George] literally does this kind of thing for a living. Which isn’t to say it was easy, but at least he keeps close enough tabs on the industry to find a suitable ARM solution at a price that makes sense, namely the Allwinner F1C100s. This diminutive chip offers both RAM and CPU in a single package, which greatly simplifies the overall design and construction of the card.

With a root filesystem that weighs in at just 2.4 MB, the environment on the card is minimal to say the least. There’s no networking, limited I/O, and forget about running any heavy software. But it does boot in about six seconds, and [George] managed to pack in a MicroPython interpreter and a copy of the classic Unix dungeon crawler rogue.

Oh yeah, and it also has his resume and some samples of his photography onboard. It is, after all, a business card. All the user has to do is plug it into the USB port of their computer and wait for the virtual serial port to pop up that will let them log into the system running on the card. It also shows up as a USB Mass Storage device for recipients who might not be quite as adept at the command line.

In addition to the high-level documentation for this project, [George] has also prepared a deeper write-up that goes into more technical detail for anyone who might be looking to follow in his footsteps. Thanks to all of the source code that he’s made available, it should be a lot easier for the next person to get their own disposable pocket computer up and running.

We’ve seen all manner of electronic business cards over the years, but never anything quite like this. Which, of course, is quite the point. If you’re ever given a business card that doubles as a computer running a full-fledged operating system on it, you aren’t likely to forget it anytime soon.

The Use And Abuse Of CT Scanners

September 20, 2018 by 22 Comments

David Mills is as a research scientist at the cutting edge of medical imaging. His work doesn’t involve the scanners you might find yourself being thrust into in a hospital should you be unfortunate enough to injure yourself. He’s working with a higher grade of equipment, he pushes the boundaries of the art with much smaller, very high resolution CT scanners for research at a university dental school.

He’s also a friend of Hackaday and we were excited for his talk on interesting uses for CT scanners at EMF Camp this summer. David takes us into that world with history of these tools, a few examples of teeth and bone scans, and then delves into some of the more unusual applications to which his very specialist equipment has been applied. Join me after the break as we cover the lesser known ways to put x-ray technology to work.

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HackBusting: Can You Fake A TV Remote With A Lighter And Some Paper?

February 20, 2017 by 62 Comments

We recently published an article where someone apparently controlled their TV by simulating a remote with merely a lighter and a sheet of paper. The paper had a barcode like cutout for a supposed “Universal Standby Signal”. The video rightfully attracted a substantial crowd, some awestruck by its simplicity, others sceptical about its claims.

Coming from some generic “Viral Life Hack” production house, the characteristic blare of background music, more suited to an underground rave than a technical video, certainly did not do it any favours. As any moderately experienced campaigner would know, modern televisions and remotes have been carefully engineered  to prevent such mishaps. Many of us at Hackaday, were under the impression that it would take something slightly more sophisticated than a fluorescent-bodied lighter and a crisp sheet of A4 to deceive the system. So we tested it out. Our verdict? Unlikely, but not impossible. (And we’re pretty sure that the video is a fake either way.) But enough speculation, we’re here to do science.

Continue reading “HackBusting: Can You Fake A TV Remote With A Lighter And Some Paper?” →

Tennis Ball Cannon

Tennis Ball Cannon With Clear Combustion Chamber

January 9, 2016 by 7 Comments

[hw97karbine] has made a pretty cool tennis ball cannon. While making a cannon of this sort is nothing new to us, we were impressed by the effort taken to get a stoichiometrically ideal mixture of 3.2% butane and air in the combustion chamber.

[hw97karbine] filled a syringe with butane and then dosed exact amounts into the chamber using a hole in the back. To control the air mixture he marked lines on the outside of the cylinder with magic marker. Simple but effective.

More rewarding than the methods was the cool slow-mo videography of the explosions in the chamber. You really have to check it out. [hw97karbine] shows clearly the difference between a well-balanced fuel to air mixture and a poorly balanced one. It’s one thing to say that more fuel does not mean better combustion, as we all remember from our personal potato cannon experiences, but it’s another thing entirely to see it.

[Via Reddit]

Embed With Elliot: I2C Bus Scanning

June 25, 2015 by 15 Comments

A lot of great ICs use I2C to communicate, but debugging a non-working I2C setup can be opaque, especially if you’re just getting started with the protocol/bus. An I2C bus scanner can be a helpful first step in debugging an I2C system. Are all the devices that I think should be present actually there and responding? Do they all work at the bus speed that I’m trying to run? If you’ve got an Arduino or Bus Pirate sitting around, you’re only seconds away from scanning your I2C bus, and answering these questions.

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Ask Hackaday: Can Paper USB Business Cards Exist?

August 25, 2014 by 72 Comments

swivel business card

The swivelCard Kickstarter campaign recently received a lot of press coverage and makes some impressive claims as their goal is the development of USB and NFC business cards at a $3 unit price. While most USB-enabled business cards we featured on Hackaday were made of standard FR4, this particular card is made of paper as the project description states the team patented

a system for turning regular paper into a USB drive.

As you can guess this piqued our interest, as all paper based technologies we had seen until now mostly consisted of either printed PCBs or paper batteries. ‘Printing a USB drive on regular paper’ (as the video says) would therefore involve printing functional USB and NFC controllers.

Luckily enough a quick Google search for the patents shown in one of the pictures (patent1, patent2) taught us that a storage circuitry is embedded under the printed USB pads, which may imply that the team had an Application-Specific Integrated Circuit (ASIC) designed or that they simply found one they could use for their own purposes. From the video we learn that ‘each card has a unique ID and can individually be programmed’ (the card, not the UID) and that it can be setup to open any webpage URL. The latter can even be modified after the card has been handed out, hinting that the final recipient would go to a ‘www.swivelcard.com/XXXX” type of address. We therefore got confused by

Imagine giving your business card with pictures, videos, presentations, and websites for the recipient to interact with!

paragraph that the project description contains.

This leads us to one key question we have: what kind of USB drive can make a given user visit a particular website, given that he may have Linux, Windows, Mac or any other OS? They all have similar USB enumeration processes and different key strokes to launch a browser… our wild guess is that it may be detected as storage with a single html file in it. Unfortunately for us the USB detection process is not included in the video.

Our final question: Is it possible to embed both USB and NFC controllers in a thin piece of paper without worrying about broken ICs (see picture above)? NFC enabled passports have obviously been around for a long time but we couldn’t find the same for USB drives.

Possible or not, we would definitely love having one in our hands!

Edit: One of our kind readers pointed out that this campaign actually is a re-launch of a failed indiegogo one which provides more details about the technology and confirms our assumptions.