Something shady's going on...

Sat down a couple of hours and got started on a multicolor display-routine - only to find out it didn't work. At all...

After extensive troubleshooting of what I believed to be was faulty cables, I've redone all the cables except the powercables in the machine. Now everything is nice and pluggable/unpluggable in a easy manner.

The problem wasn't in the cables however, but the cabling still needed some work.
When I tried a different version of the digitalWriteFast it, for some peculiar reason, broke the pins I was using so I tried plugging the display into another set. The refresh rate of the screen was becoming rather slow and at that time I didn't connect that those pins were not "accelerated" by digitalWriteFast.
Also - the new library was approximately 1.5 x slower than the old. Doh.

So anyway - I reverted to the old library and the old pins and now my code could do its work properly.

1) Multicolor display. Four different reds and one black layer.
Here it's simply displaying f(y)=red, but any pixel can be any shade. 

At the moment it can display 5 different "colors" (4 red + 1 black). The code that enables different shades is quite slow since it needs to check for different values and also draw the screen multiple times, so with 4 colors I'm pushing 'the little MCU that could' beyond its comfort zone.

I will do further testing with SPI enabled since I need to get the time needed for each update to a lot less than it is currently taking. It is currently updating a full 4+1 color frame at 19 ms, which is "really slow". I hope to get this down to under 1 ms, if possible...