With this 'controller' working I was able to find an approximate mix for the colors I want.

I thought that I could find the relation I was looking for in order to get a formula rgb->this_led by finding the 1st white, ie the lowest values for each color that produced a white color.

I got that at 19,1,5 (r,g,b) and it looks to be linear, 19*n, 1*n, 5*n produces whites until n=13, with n=14 the red color overflows and the relation is lost.

I guess that there should be a way to keep that relation, the obvious MOD is, of course, wrong, because the red overflows first.

n=1 -> 19, 1, 5

n=2 -> 38, 2, 10

n=3 -> 57, 3, 15

n=4 -> 76, 4, 20

n=5 -> 95, 5, 25

n=6 -> 114, 6, 30

n=7 -> 133, 7, 35

n=8 -> 152, 8, 40

n=9 -> 171, 9, 45

n=10 -> 190, 10, 50

n=11 -> 209, 11, 55

n=12 -> 228, 12, 60

n=13 -> 247, 13, 65

n=14 -> 10, 14, 70

n=15 -> 29, 15, 75

n=16 -> 48, 16, 80

n=17 -> 67, 17, 85

n=18 -> 86, 18, 90

n=19 -> 105, 19, 95

I'm at a loss, any suggestions ?

thanks!