So today I finished the second version of Alpen Clack -- this one built from scratch. As always, the most work-intensive part was soldering everything together. This time I used non-insulated wire, and added some kapton tape where it might touch anything -- this was much faster than removing the insulation from wires for soldering. The finished connections, before closing the keyboard:

Next comes the programming. I used the same firmware as for version one, except this time I had 6 columns and 17 rows (I kept the layout rotated 90°, as this is much easier to fit in 80 columns of source code). I also drilled a small hole for the reset button, to be able to press it with a pin.

Defining the layout was much easier this time, because of the saner matrix -- the Pololu A* Mini has enough pins broken out for me to not care so much about saving them. Still, I miscalculated a little bit and had to use one of the LED pins. That still left me two LEDs for CapsLock and ScrollLock (no NumLock), so it's fine.

Once everything was ready, I spent the customary 4 hours tearing my hair off and staring at the code, trying to debug a problem with it. In the end, it turned out that the compiler was caching a little more than it should, and recompiling everything from scratch solved it.