Now Even Your Business Card Can Run Linux

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.

There’s More To Designing A PCB Business Card Than Meets The Eye

A curious custom that survives from the pre-computer era is that of the business card. If you walk the halls at a trade event you’ll come a way with a stack of these, each bearing the contact details of someone you’ve encountered, and each in a world of social media and online contact destined to languish in some dusty corner of your desk. In the 21st century, when electronic contacts harvested by a mobile phone have the sticking power, how can a piece of card with its roots in a bygone era hope to compete?

It’s a question [Anthony Kouttron] has addressed in the design of his thoroughly modern business card, and along the way he’s treated us to an interesting narrative on how to make the card both useful beyond mere contact details as well as delivering that electronic contact. The resulting card has an array of  rulers and footprints as an electronic designer’s aid, as well as an NFC antenna and chip that lights an LED and delivers his website address when scanned. There are some small compromises such as PCB pads under the NFC antenna, but as he explains in the video below, they aren’t enough to stop it working. He’s put his work in a GitHub repository, should you wish to do something similar.

There’s a rich vein of business card projects on these pages, but so far surprisingly few are NFC equipped. That didn’t stop someone from making an NFC-enabled card with user interaction though.

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Magic 8 Ball Business Card Will Answer All Your Questions

The PCB business card has long been a staple amongst the freelance EE set. It’s a way to show potential clients that you can do the job, as well as leave a great first impression. Some are simple blinkenlights devices, others have contact information on USB storage. We reckon that [Seamus] has really hit it out of the park with this one, though.

That’s right- this business card riffs on the classic Magic 8-ball toy. Ask a question, shake the card, and it’ll light an LED with the corresponding answer to your query. Use it as a desk toy, or break deadlocks in meetings by looking to the card for the correct course of action.

It’s a very tasteful build, showing off [Seamus]’s minimalist chops – consisting of just a decade counter, a tilt sensor, and some LEDs. When the card is shaken, the tilt sensor outputs a series of pulses to the clock line of the decade counter, whose outputs are the 8 LEDs. When the tilt sensor settles, it lands on the final answer.

We think it’s a great card, which shows off both fundamental technical skills as well as a certain flair and creativity which can be key to landing exciting projects. It doesn’t hurt that it’s good fun, to boot. For another take on the Magic 8-ball, check out this build that can give you a Yes/No answer on demand.

NFC Enabled Business Card

[Sjaak] is back at it again with the cool PCB business cards, this time alleviating the burden to physically type his contact information into your phone. But NFC isn’t the only cool thing on this PCB – as always, his aesthetics don’t disappoint.

When we see [Sjaak’s] card, the future seems to be the now – not only do we have business cards that can take our pulse, we have business cards that actively help facilitate the exchange of contact information. I know what you’re thinking. “Business cards made of paper do that already.” That’s true if you read them. You have to physically remember you have the card (aka not put it through the wash), and, if you’re like most folks, you’ll ultimately enter the information into your cell phone’s contact list. Why not skip the whole reading thing? You know, just zap your contact information into the contact list of people automatically?

Maybe this is exactly what [Sjaak] thought when he built his NFC enabled business card. Maybe not. Regardless, [Sjaak’s] card is beautiful – both in implementation and aesthetics. Powered by “a nice little NFC EEPROM from NXP”, (the NT3H1101) the business card even has an energy harvesting mode. Moreover, one can interact with the card via four buttons and an LED. The LED informs the user what mode the card is currently in, and the buttons choose which URL is sent to users via NFC. To add icing to the cake, the back of the PCB is decked out via [Sjaak’s] custom full-color decal process we covered back in August.

As great as it looks, the card still needs some improvement. “I still need to tackle the sharp and protruding components on the front, which will ruin your wallet.” But, in our eyes, the card is surely on its way to greatness, and we look forward to seeing its final form. However, if you’re anything like us, you might want to see some other rad PCB business cards while you wait. If that’s the case, we recommend this logic based finite machine and this card made by a hackaday author.

Full Color PCB Business Card

[Sjaak], in electronic hobbyist tradition, started to design a PCB business card. However, he quickly became disillusioned with the coloring options made available by the standard PCB manufacturing process. While most learn to work with a limited color palette, [Sjaak] had another idea. PCB decals for full-color control.

As [Sjaak] realized early in his PCB journey, the downside of all PCB business cards (and PCBs in general) is the limited number of colors you can use which are dictated by the layers you have to work with: FR4, soldermask, silkscreen and bare copper. Some people get crafty, creating new color combinations by stacking layers for hues, but even that technique doesn’t come close to a full palette.

The commercial off-the-shelf out of the box solution [Sjaak] found was decal slide paper. For those of you not prone to candle making or car decorating, decals are printable plastic film that can be used to decorate ceramics, glass or other smooth surfaces. Both clear and white versions can be found in most hobby stores. Once obtained, an inkjet or laser printer can print directly onto the photo paper-like material, lending the decals an infinite range of colors.

[Sjaak] bought clear film and designed his PCB with black soldermask and white silkscreen. Once the PCBs had come in, [Sjaak] got to work applying the decals with a transfer method by placing one into water, waiting a bit until the decal lets loose and then are carefully applied to a PCB. [Sjaak] reports that the process is a bit trickery because the film is very thin and is easily crinkled. But, difficulties overcome, the PCB then needs to dry for twenty-four hours. From there, it’s into the oven for 10 minutes at 248 degrees Fahrenheit (120 degrees Celsius) followed by an optional clear coating. Although the process is a bit involved, judging from his pictures we think the results are worth it, producing something that would stand out; which, in the end, is the goal of a PCB business card.

With all this in mind, we think that the logical progression is to incorporate digital logic or go full DIY and CNC or laser engrave your own business card.