3D-printed holder for magnetic spheres built with OpenSCAD

When I built the low-cost and precise rotary encoder with magnetic spheres I used 21 spheres because they fitted nicely in the other parts of the build I had around.

However, if an arbitrary number of spheres is to be used then an appropriate holder must be built.


Linux Device-Tree and gpio-keys driver on BeagleBone Black

I had to wire up a simple navigation keypad to a BeagleBone Black for a prototype, and I used the gpio-keys driver configured via a device tree overlay.


Low-cost and precise rotary encoder with magnetic spheres

You know what they say that constraints drive creativity, I think this post is just another little example of that.

Usually I do not put time constraints to my hobby projects, but I make sure to have some other kind of constraints, like keeping the cost low and trying to reuse stuff that I already have.

In this case I needed a way to measure the angle and speed of a rotating object for some of my projects, and I wanted a rotary encoder that was inexpensive, but precise enough to work at very low speeds.


libam7xxx-0.1.7 released

The libam7xxx-0.1.7 release is out; it's a maintenance release with no big new features.


Fun with flexagons, and SVG

If you don't know Vihart and her "Hexaflexagon series", go check it out:


drupal-init-tools: quick and easy Drupal 8 setup

Drupal 8 is quite an improvement over previous versions of Drupal with regard to the reproducibility of a site from a minimal source repository.

The recommended way to set up a new Drupal 8 site is to use composer, and the most convenient way to do that is via drupal-composer/drupal-project, which brings in Drush and drupal-console as per-site dependencies; from there the site can be installed and managed.

However the fact that Drush and drupal-console are per-site dependencies poses a problem: they are not available until the site dependencies have been downloaded, this means that it's not really possible to add “bootstrapping” commands to them to make it easier to set up new projects.


Drupal 8 migration log - Part 1 - intro, the front page

Most of the information I have come across about migrating from Drupal 6 to Drupal 8 is about migrating content, however before tackling this problem another one must be solved, maybe it is obvious and hence understated, so let's spell it out loud: preserving the site functionality.


libam7xxx-0.1.6 released

The libam7xxx-0.1.6 release is out; it's a maintenance release with no big new features.


Automatic motion trail effect with OpenCV

You know that effect in some videos where objects moving in the scene leave a trail of their old position?


Linux KMS driver for Acer C120

Hans de Goede informs me that he has been working on gm12u320-kms: a new linux kernel driver for the Acer C120 mini projector, and possibly other devices based on the Grain Media GM12U320 USB3 bridge chip.