Colors
The main module of besteLampe! has six separate PWM channels to drive six different groups of LEDs. The intention is to mix six LED colors.
So why six color channels?
You might have heard that three light colors are enough to create any color that humans can perceive: red, green. That's kind of correct, but only as long as the light goes directly into the human's eye.
Lighting a room/scene/object is more complex. You need a full color spectrum for the objects to reflect or absorb, or their colors will look dull and artificial. The fullness of the color spectrum of a light source can be described by the color rendering index, short CRI.
Combining the light from red, green and blue LEDs will give a white light with a low (bad) CRI.
LEDs that emit white light exist, and they can have different CRI values (usually much better than adding RGB colors) and different color temperatures (which is basically independent from the CRI).
If you want to adjust your color temperature, you can either mix your white light (which has a specific color temperature) with red or blue light. This will decrease your CRI.
Or you can have multiple kinds of white LEDs, e.g. cold white with 6500K and warm white with 2000K. (Yes, it's confusing that higher color temperature equals cold light, but that's how things are.) and mix their light in varying amounts. This (roughly) gives you every color temperature between 2000K and 6500K, and a CRI that is roughly as good as that of the individual white LEDs.
But there's still a problem. You can map the color of LEDs on a CIE chromaticity diagram. Mixing warm white and cold white, you get any color that is on the straight line between both LEDs' colors. But whites with different color temperatures don't lie on a straight line. They lie on a curve called the Planckian locus, which describes the emission of incandescent light sources. To match that curve, you may need to add small amounts of red, green or blue to the mixture of both whites. That's probably part of the reason why 5-channel LEDs and LED strips exists.
To make things even more complex, the natural sun light including atmospheric effects changes its color across the day in a way that resembles the Planckian locus, but is actually a more complex curve (or point cloud, that can be approximated by a curve).
Currently, there are very few software/firmware implementations that correctly compute the amounts of all five channels to get the correct light color, while keeping a good CRI. Most implementations don't even try to do it at all, and just mix the two whites.
I'm planning to use the sixth channel for Amber light. Why Amber? And why not mix it from the five other channels?
To be continued...