Add WS2812B binding

src/Iot.Device.Bindings/Iot.Device.Bindings.csproj

@@ -1,4 +1,4 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
     <TargetFramework>netcoreapp2.1</TargetFramework>

src/devices/Common/Iot/Device/Graphics/BitmapImage.cs

@@ -0,0 +1,39 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System;
+using System.Drawing;
+
+namespace Iot.Device.Graphics
+{
+    public abstract class BitmapImage
+    {
+        protected BitmapImage(byte[] data, int width, int height, int stride)
+        {
+            _data = data;
+            Width = width;
+            Height = height;
+            Stride = stride;
+        }
+
+        private readonly byte[] _data;
+        public Span<byte> Data => _data;
+        public int Width { get; }
+        public int Height { get; }
+        public int Stride { get; }
+
+        public abstract void SetPixel(int x, int y, Color c);
+
+        public virtual void Clear(Color c = default)
+        {
+            for (int y = 0; y < Height; y++)
+            {
+                for (int x = 0; x < Width; x++)
+                {
+                    SetPixel(x, y, c);
+                }
+            }
+        }
+    }
+}

src/devices/Ws2812B/BitmapImageNeo3.cs

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+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using Iot.Device.Graphics;
+using System.Drawing;
+
+namespace Iot.Device.Ws2812b
+{
+    /// <summary>
+    /// Special 24bit RGB format for Neo pixel LEDs where each bit is converted to 3 bits.
+    /// A one is converted to 110, a zero is converted to 100.
+    /// </summary>
+    public class BitmapImageNeo3 : BitmapImage
+    {
+        private const int BytesPerComponent = 3;
+        private const int BytesPerPixel = BytesPerComponent * 3;
+        // The Neo Pixels require a 50us delay (all zeros) after. Since Spi freq is not exactly
+        // as requested 100us is used here with good practical results. 100us @ 2.4Mbps and 8bit
+        // data means we have to add 30 bytes of zero padding.
+        private const int ResetDelayInBytes = 30;
+
+        public BitmapImageNeo3(int width, int height)
+            : base(new byte[width * height * BytesPerPixel + ResetDelayInBytes], width, height, width * BytesPerPixel)
+        {
+        }
+
+        public override void SetPixel(int x, int y, Color c)
+        {
+            var offset = y * Stride + x * BytesPerPixel;
+            Data[offset++] = _lookup[c.G * BytesPerComponent + 0];
+            Data[offset++] = _lookup[c.G * BytesPerComponent + 1];
+            Data[offset++] = _lookup[c.G * BytesPerComponent + 2];
+            Data[offset++] = _lookup[c.R * BytesPerComponent + 0];
+            Data[offset++] = _lookup[c.R * BytesPerComponent + 1];
+            Data[offset++] = _lookup[c.R * BytesPerComponent + 2];
+            Data[offset++] = _lookup[c.B * BytesPerComponent + 0];
+            Data[offset++] = _lookup[c.B * BytesPerComponent + 1];
+            Data[offset++] = _lookup[c.B * BytesPerComponent + 2];
+        }
+
+        private static readonly byte[] _lookup = new byte[256 * BytesPerComponent];
+        static BitmapImageNeo3()
+        {
+            for (int i = 0; i < 256; i++)
+            {
+                int data = 0;
+                for (int j = 7; j >= 0; j--)
+                {
+                    data = (data << 3) | 0b100 | ((i >> j) << 1) & 2;
+                }
+                _lookup[i * BytesPerComponent + 0] = unchecked((byte)(data >> 16));
+                _lookup[i * BytesPerComponent + 1] = unchecked((byte)(data >> 8));
+                _lookup[i * BytesPerComponent + 2] = unchecked((byte)(data >> 0));
+            }
+        }
+    }
+}

src/devices/Ws2812B/README.md

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+# Ws2812b
+
+## Summary
+
+This binding allows you to update the RGB LEDs on Ws2812b based strips and matrices.
+
+To see how to use the binding in code, see the [sample](samples/README.md).
+
+## Device Family
+
+* WS2812B: [Datasheet](https://cdn-shop.adafruit.com/datasheets/WS2812B.pdf)
+
+## Binding Notes
+
+### Raspberry Pi setup (/boot/config.txt)
+
+* Make sure spi is enabled<br>
+  `dtparam=spi=on`
+
+* Make sure SPI don't change speed fix the core clock<br>
+  `core_freq=250`<br>
+  `core_freq_min=250`
+
+## References 
+
+* [Neo pixels guide](https://learn.adafruit.com/adafruit-neopixel-uberguide)
+* [Neo pixels x8 stick](https://www.adafruit.com/product/1426)

src/devices/Ws2812B/Ws2812B.cs

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+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System.Device.Spi;
+
+namespace Iot.Device.Ws2812b
+{
+    public class Ws2812b
+    {
+        private readonly SpiDevice _spiDevice;
+        public BitmapImageNeo3 Image { get; }
+
+        public Ws2812b(SpiDevice spiDevice, int width, int height = 1)
+        {
+            _spiDevice = spiDevice;
+            _spiDevice.ConnectionSettings.ClockFrequency = 2_400_000;
+            _spiDevice.ConnectionSettings.Mode = SpiMode.Mode0;
+            _spiDevice.ConnectionSettings.DataBitLength = 8;
+            Image = new BitmapImageNeo3(width, height);
+        }
+
+        public void Update() => _spiDevice.Write(Image.Data);
+    }
+}

src/devices/Ws2812B/Ws2812b.csproj

@@ -0,0 +1,17 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>netcoreapp2.1</TargetFramework>
+    <!--Disabling default items so samples source won't get build by the main library-->
+    <EnableDefaultItems>false</EnableDefaultItems>
+    <LangVersion>latest</LangVersion>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <Compile Include="*.cs" />
+    <Compile Include="../Common/Iot/Device/Graphics/BitmapImage.cs" />
+    <None Include="README.md" />
+    <PackageReference Include="System.Device.Gpio" Version="0.1.0-prerelease*" />
+  </ItemGroup>
+
+</Project>

src/devices/Ws2812B/samples/README.md

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+# Drive Neo pixel strip (x8) from Raspberry Pi
+
+This [program](Ws2812b.Sample.cs) demonstrates how to use the [Neo pixel binding](../Ws2812b.cs) to drive an 8 Neo Pixel stick from a Raspberry Pi.
+
+It shows how to set the colors of each LED using `SetPixel` and `Update`. Then it shows how to fade in one of the LEDs in a loop.
+
+## Run the sample
+
+```console
+cd samples
+dotnet build -c release -o out
+dotnet out/Ws2812b.Samples.dll
+```
+
+## Breadboard layout
+
+The following [fritzing diagram](rpi-neo-pixels.fzz) demonstrates how you should wire your device in order to run the program. It uses the GND, 5V and MOSI pins on the Raspberry Pi.
+
+![Raspberry Pi Breadboard diagram](rpi-neo-pixels_bb.png)
+
+## Hardware elements
+
+The following elements are used in this sample:
+
+* [Raspberry Pi 3](https://www.adafruit.com/product/3055)
+* [Neo pixels x8 stick](https://www.adafruit.com/product/1426)

src/devices/Ws2812B/samples/Ws2812b.Sample.cs

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+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System.Device.Spi;
+using System.Device.Spi.Drivers;
+using System.Drawing;
+
+namespace Iot.Device.Ws2812b.Samples
+{
+    class Program
+    {
+        static void Main()
+        {
+		    // Create a Neo Pixel x8 stick on spi 0.0
+            var spi = new UnixSpiDevice(new SpiConnectionSettings(0, 0));
+            var neo = new Ws2812b(spi, 8);
+
+            // Display basic colors for 5 sec
+            BitmapImageNeo3 img = neo.Image;
+            img.SetPixel(0, 0, Color.White);
+            img.SetPixel(1, 0, Color.Red);
+            img.SetPixel(2, 0, Color.Green);
+            img.SetPixel(3, 0, Color.Blue);
+            img.SetPixel(4, 0, Color.Yellow);
+            img.SetPixel(5, 0, Color.Cyan);
+            img.SetPixel(6, 0, Color.Magenta);
+            img.SetPixel(7, 0, Color.FromArgb(unchecked((int)0xffff8000)));
+            neo.Update();
+            System.Threading.Thread.Sleep(5000);
+
+            // Fade in first pixel
+            byte b = 0;
+            img.Clear();
+            while (true)
+            {
+                img.SetPixel(0, 0, Color.FromArgb(0xff, b, b, b));
+                neo.Update();
+                System.Threading.Thread.Sleep(10);
+                b++;
+            }
+        }
+    }
+}

src/devices/Ws2812B/samples/Ws2812b.Samples.csproj

@@ -0,0 +1,12 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>netcoreapp2.1</TargetFramework>
+  </PropertyGroup>
+
+  <ItemGroup>
+  	<ProjectReference Include="../Ws2812b.csproj" />
+  </ItemGroup>
+
+</Project>