SK6812 RGBWs behaving... strange?

Hey Community,

I've built my own 4x4 LED matrix using SK6812 LEDs. Trying to control them via the Adafruit NeoPixel Library, however, it behaves very strange.

This is my program:

#include <arduino.h>
#include <Adafruit_NeoPixel.h>

#define PIN 6

Adafruit_NeoPixel strip = Adafruit_NeoPixel(16, PIN, NEO_GRBW + NEO_KHZ800);

void setup() {

void loop() {
  for(int i = 0; i < 16; i++) {
    strip.setPixelColor(i, 255, 0, 0, 100);

So every LED should light up in red, right? Well, this is the result:

I then tried to use the "simple_rgbw" library from this topic, but again, it doesn't do what it's supposed to do. Here is what it looks like during its first loop:

The fading, however, works without any problem so I think the data line works fine, otherwise the colors wouldn't be in this... pattern, right?
I don't really know what the problem is here, so maybe someone of you has a good idea of what's happening.


Are your SK6812 LEDs actually RGBW? A quick Google seems to show that it comes in both RGB and RGBW versions.

You can try NEO_GRB instead of NEO_GRBW and see if you get all red colors as you expect.

Sometimes it is just as easy. That was it, thank you very much. Confusing though, as the product description from where I bought it said they are RGBW...
Thank you!