Hallo Michael and or Vasques666,
I got my NCS314 working over the weekend and have also been looking into the possibility to fade in/out. I got the NCS314 v2.3 that uses 2 HV5122 drivers and I have the feeling that the fading is not possible with these drivers but then I saw your post where you mention that an NCT818 with the same driver chips has working fade in/out. Looking at the code pasted above though I do not see how that code would enable fading.
If someone can share the entire code for a working fade in/out with the HV5122 driver would be great.
@michael, I see you also have the NCS314 but with the single 64-bit driver (so version 3.x of the hardware I guess). If the fading works for you but the digits get mixed up you likely have a mixup somewhere with the bitpatterns you send over SPI.
For the HV5122 you send twice 32bit unsigned longs, in both cases the 2 most significant bits are for the dots and then you have 3 * 10 bits for the numbers. It took me while to figure it out, not sure how good you are with bit-logic but if you share your code (the original and the mixed up fading code) happy to have a look.
Groeten Johan