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Ws28xx / SK6812 LED drivers

This binding allows you to update the RGB LEDs on Ws28xx / SK6812 and based strips and matrices.

To see how to use the binding in code, see the sample.

Documentation

Board

Neo pixels / SK6812

Raspberry Pi Breadboard diagram

WS2808

WS2808 diagram

Usage

using System;
using System.Collections.Generic;
using System.Device.Spi;
using System.Drawing;
using Iot.Device.Graphics;
using Iot.Device.Ws28xx;

// Configure the count of pixels
const int Count = 8;
Console.Clear();

SpiConnectionSettings settings = new(0, 0)
{
    ClockFrequency = 2_400_000,
    Mode = SpiMode.Mode0,
    DataBitLength = 8
};
using SpiDevice spi = SpiDevice.Create(settings);

Ws28xx neo = new Ws2808(spi, count);
// Ws28xx neo = new Ws2812b(spi, Count);
// Ws2815b neo = new Ws2815b(spi, ledCount);

while (true)
{
    Rainbow(neo, Count);
    System.Threading.Thread.Sleep(100);
}

void Rainbow(Ws28xx neo, int count, int iterations = 1)
{
    BitmapImage img = neo.Image;
    for (var i = 0; i < 255 * iterations; i++)
    {
        for (var j = 0; j < count; j++)
        {
            img.SetPixel(j, 0, Wheel((i + j) & 255));
        }

        neo.Update();
    }
}

Note:

Using the SK6812 is almost the same, but the alpha channel of the color is used for the white LED. This means that the predefined color definitions (like System.Drawing.Color.Red) will not work correctly as they have the alpha channel set to 255 (0xFF). That will turn the white LED always on. See the sample for the main differences to the above code. Because System.Drawing.Color is a readonly struct, it's not possible to change the any channel directly. In order to correctly set Red, use Color.FromArgb(0, 255, 0, 0). For setting the white LED, use Color.FromArgb(255, 0, 0, 0). It's also possible to use an existing definition and remove the white channel like this:

var color = Color.HotPink;
var newColor = Color.FromArgb(0, color.R, color.G, color.B);

Binding Notes

Raspberry Pi setup (/boot/firmware/config.txt)

Note

Prior to Bookworm, Raspberry Pi OS stored the boot partition at /boot/. Since Bookworm, the boot partition is located at /boot/firmware/. Adjust the previous line to be sudo nano /boot/firmware/config.txt if you have an older OS version.

  • Make sure SPI is enabled
dtparam=spi=on
  • To make sure SPI doesn't change speed fix the core clock:
core_freq=250
core_freq_min=250