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A Buildroot distribution small enough to run on a business card
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.github/workflows Implement GitHub Action to compile firmware image Jan 2, 2020
board/businesscard Remove generated SD card image Oct 5, 2019
buildroot @ 5b4e32c Bump Buildroot version to 2019.05.1 Aug 17, 2019
doc add schematics Dec 28, 2019
package businesscard-flashdrive: Provide useful info about photography Jan 23, 2020
.gitmodules Initial commit, with buildroot submodule Apr 30, 2019 Implement package for flashdrive image Oct 5, 2019 Add explicit license grant section Jan 2, 2020
external.desc Initial commit, with buildroot submodule Apr 30, 2019 Initial commit, with buildroot submodule Apr 30, 2019

Business Card Linux

Actions Status

This is the Linux distribution small enough to run from the 8MB of storage on my Linux-powered business card. It is powered by the Allwinner F1C100s, a $1.40 Linux-capable ARM system-on-chip. This repository is the source code for its firmware image, based on Buildroot 2019.05. This directory is a "Buildroot external," providing a few patches, additional packages, and board support files on top of mainline Buildroot.

For a complete write-up, see my blog post about the project.

business card top

Patched Linux and U-Boot

I lightly patched the Linux kernel and U-Boot to get all the hardware peripherals working. You can find my forks here:

  • Linux v5.0.2 (patched to enable USB gadget mode)
  • U-Boot (patched to support the F1C100s)


Make sure submodules are initialized:

git submodule update --init

Change to the top-level Buildroot directory:

cd buildroot

Initialize the configuration, including the defconfig and this external directory:

make BR2_EXTERNAL=$PWD/../ thirtythreeforty_businesscard_defconfig

And compile:


This may take a couple hours to do from scratch, depending on the speed of your machine.


If you have a Lichee Pi Nano with a flash chip, or one of my blank business cards, you can flash it with the following command. Make sure the board is in FEL mode using dmesg or similar.

output/host/bin/sunxi-fel -p spiflash-write 0 output/images/flash.bin

You can erase the card after it boots by simply logging in (as root) and erasing the flash manually:

dd if=/dev/zero of=/dev/mtd0

Don't erase it unless you're prepared to burn a new image!


Subject to the below exceptions, code is released under the GNU General Public License, version 2 or (at your option) any later version. See also the Buildroot license notice for more nuances about the meaning of this license.

Patches are not covered by this license. Instead, they are covered by the license of the software to which the patches are applied.

Finally, files in the businesscard-flashdrive package, including its README, my resume, and my photography, remain proprietary and are not released under the GPL. If you would like to build your own firmware based on this, simply remove those files, or deselect the package during build.

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