F1C100s

The F1C100S (and the F1C200S) is a super simple CPU to use – it’s QFN, it has RAM built-in, and it can run Linux. It just makes sense that we bring it up to you once again, this time, on this dual-board computer by [minilogic]. The boards look super accessible to build for a Linux computer, and it’s alright if you assemble only one of them, too – the second board just makes this computer all that much nicer to use!

One the main board, you get the CPU itself, a couple USB ports, headphone and mic jacks, a microphone, a microSD socket, power management, SPI flash chip, plus some buttons, headers and USB-UART for debug. Add the second board, however, and you get a HDMI video output socket, a RGBTTL LCD header, LiIon battery support, RTC, and even FM radio with TV input.

One problem with this computer – it’s not open-source in the way that we expect and respect, as there’s no board files to be seen. However, at least the schematics are public, so it shouldn’t be hard, and the author provides quite a bit of example code for the F1C100S, which softens the blow. Until the design files are properly published, we can at least learn from the idea and the schematics. If you like what the F1C100S CPU offers, there are other projects you can take things from too, like this low-cost handheld we’re patiently waiting for, or this Linux-powered business card.

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.