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.

50 thoughts on “Now Even Your Business Card Can Run Linux

    1. The card is only $2.88 (ignoring shipping and time costs) to make, e-ink would’ve added a lot more to the cost. It would’ve looked cool, true, but then it wouldn’t be easy to give away. Also would’ve added bulk to the card.

        1. I remember flashing AMD5120 openwrt routers with UART only (zmodem and al).

          Otherwise, I was wondering if such chip was also available in QFP 128 package (might be easier to solder on a standard breakout board).

          Thinking how much it would cost to do a bluepill clone, but with such chip. The last blackpill has optional traces to solder an SPI flash:

          https://www.cnx-software.com/2019/12/24/stm32-black-pill-board-features-stm32f4-cortex-m4-mcu-optional-spi-flash/

          1. There are similar chips available in QFP (the Allwinner V3s is probably the closest in terms of hackability and availability). But they are more expensive, and if you have a reflow oven it’s not substantially different either way. At the end of the day, the F1C100s was “just right” for all the reasons I give.

          1. Yes, but I did my research before selecting it. And I immediately threw away the old BSP that had been packaged for it and did my own work based on the latest Buildroot.

            Relying on cheap dev board BSPs is not a great way to get them working.

  1. First we have a laser cut business card containing somewhat usable lockpicks. Then we have a few renditions of USB hosts on business cards, the most notable being one which implements a tiny flash drive using an AVR. Then we have an Arduino business card with an nRF24L01+ onboard. And now we have an embedded Linux system powered from USB with a USB UART for communication.

    Dr. Philippe Cadic (pwavrobot), a medical doctor and electronics engineer from France, is working on a business card with LoRA and a tiny built-in display running on an ESP32. He says he will bring it to DEF CON next year.

    1. I understand how you feel, but I feel like being handed the thing by the guy who made it is different from finding something on the floor or being handed from a huge bucket at a trade booth.

      In that case, I feel it’s more akin to just buying a brand new flash drive and making use of it. Unless, of course, you don’t trust that it’s not been tampered in the mail or on the way to store shelves.

  2. When I wrote the first Embedded Linux book 18 years ago, I never imagined someone just whipping up a bootable board for next to nothing in a toaster oven. Bravo my good man!

    Thanks for my Christmas present, it was a true joy to read about your creative card being the first to boot linux.

    1. You can! George is clearly for hire. Hire him to make a custom one for you. Going to guess that the cost will be a much more than the parts. Lots of people forget that a good chunk of the cost is really NRE.

      Nice job George, good showcase for skills. Website is nice, docs and writeup are A+. Thanks for the great article.

  3. That’s the bit larger footprint than the client OS we built for clustering computers back in 2000 based on a Linux 2.0(?) (it was a one week build and my memory isn’t serving) kernel. It was discreet, ran busybox and bits of μClinux plus Mosix and fit on a 1.44MB floppy.

    1. 500 or so Mhz, it should do, video output is up to you. Should even manage Quake with low res software rendering. When you get video output working, may as well go for Mame2000 and 8 bit emulators too.

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