Add Mpr121 binding. (#286)

* Fix readme

* Fixes.

* Merge

* Fix merge issues

* Small fix

* Fixed comments.

* Fixed screenshot.

* Fixed screenshot.

* Fixed statuses.

* Updated timer

* Fixed comments

* Small fix

src/devices/Mpr121/ChannelStatusesChangedEventArgs.cs

+// 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.Collections;
+using System.Collections.Generic;
+using System.Collections.Immutable;
+
+namespace Iot.Device.Mpr121
+{
+    /// <summary>
+    /// Represents the arguments of event rising when the channel statuses have been changed.
+    /// </summary>
+    public class ChannelStatusesChangedEventArgs : EventArgs
+    {
+        /// <summary>
+        /// The channel statuses.
+        /// </summary>
+        public IReadOnlyDictionary<Channels, bool> ChannelStatuses { get; private set; }
+
+        /// <summary>
+        /// Initialize event arguments.
+        /// </summary>
+        /// <param name="channelStatuses">The channel statuses.</param>
+        public ChannelStatusesChangedEventArgs(IReadOnlyDictionary<Channels, bool> channelStatuses) : base()
+        {
+            ChannelStatuses = channelStatuses;
+        }
+    }
+}
\ No newline at end of file

src/devices/Mpr121/Channels.cs

+// 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.
+
+namespace Iot.Device.Mpr121
+{
+    public enum Channels
+    {
+        Channel00 = 0,
+        Channel01,
+        Channel02,
+        Channel03,
+        Channel04,
+        Channel05,
+        Channel06,
+        Channel07,
+        Channel08,
+        Channel09,
+        Channel10,
+        Channel11
+    }
+}
\ No newline at end of file

src/devices/Mpr121/Mpr121.cs

+// 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.Buffers.Binary;
+using System.Collections;
+using System.Collections.Generic;
+using System.Collections.Immutable;
+using System.Device.I2c;
+using System.Threading;
+
+namespace Iot.Device.Mpr121
+{
+    /// <summary>
+    /// Supports MPR121 Proximity Capacitive Touch Sensor Controller.
+    /// </summary>
+    public class Mpr121 : IDisposable
+    {
+        /// <summary>
+        /// MPR121 Default I2C Address.
+        /// </summary>
+        public static readonly byte DefaultI2cAddress = 0x5A;
+
+        private static readonly int CHANNELS_NUMBER = Enum.GetValues(typeof(Channels)).Length;
+
+        private I2cDevice _device;
+        private Timer _timer;
+
+        private Dictionary<Channels, bool> _statuses;
+
+        private int _periodRefresh;
+
+        /// <summary>
+        /// Notifies about a the channel statuses have been changed.
+        /// Refresh period can be changed by setting PeriodRefresh property.
+        /// </summary>
+        public event EventHandler<ChannelStatusesChangedEventArgs> ChannelStatusesChanged;
+
+        /// <summary>
+        /// Gets or sets the period in milliseconds to refresh the channels statuses.
+        /// </summary>
+        /// <remark>
+        /// Set value 0 to stop the automatically refreshing. Setting the value greater than 0 will start/update auto-refresh.
+        /// </remark>
+        public int PeriodRefresh
+        {
+            get { return _periodRefresh; }
+
+            set
+            {
+                _periodRefresh = value;
+
+                if (_periodRefresh > 0)
+                {
+                    _timer.Change(TimeSpan.FromMilliseconds(_periodRefresh), TimeSpan.FromMilliseconds(_periodRefresh));
+                }
+                else
+                {
+                    // Disable the auto-refresh.
+                    _timer.Change(Timeout.Infinite, Timeout.Infinite);
+                }
+            }
+        }
+
+        /// <summary>
+        /// Initialize a MPR121 controller.
+        /// </summary>
+        /// <param name="device">The i2c device.</param>
+        /// <param name="periodRefresh">The period in milliseconds of refresing the channel statuses.</param>
+        /// <param name="configuration">The controller configuration.</param>
+        public Mpr121(I2cDevice device, int periodRefresh = -1, Mpr121Configuration configuration = null)
+        {
+            configuration = configuration ?? GetDefaultConfiguration();
+
+            _device = device;
+            _timer = new Timer(RefreshChannelStatuses, this, Timeout.Infinite, Timeout.Infinite);
+
+            _statuses = new Dictionary<Channels, bool>();
+            foreach (Channels channel in Enum.GetValues(typeof(Channels)))
+            {
+                _statuses.Add(channel, false);
+            }
+
+            InitializeController(configuration);
+
+            PeriodRefresh = periodRefresh;
+        }
+
+        public void Dispose()
+        {
+            if (_device != null)
+            {
+                _device.Dispose();
+                _device = null;
+            }
+
+            if (_timer != null)
+            {
+                _timer.Dispose();
+                _timer = null;
+            }
+        }
+
+        /// <summary>
+        /// Reads the channel statuses of MPR121 controller.
+        /// </summary>
+        public IReadOnlyDictionary<Channels, bool> ReadChannelStatuses()
+        {
+            RefreshChannelStatuses();
+
+            return _statuses.ToImmutableDictionary();
+        }
+
+        /// <summary>
+        /// Reads the channel status of MPR121 controller.
+        /// </summary>
+        /// <param name="channel">The channel to read status.</param>
+        /// <remark>
+        /// Please use ReadChannelStatuses() if you need to read statuses of multiple channels.
+        /// Using this method several times to read status for several channels can affect the performance.
+        /// </remark>
+        public bool ReadChannelStatus(Channels channel)
+        {
+            RefreshChannelStatuses();
+
+            return _statuses[channel];
+        }
+
+        private static Mpr121Configuration GetDefaultConfiguration()
+        {
+            return new Mpr121Configuration()
+            {
+                MaxHalfDeltaRising = 0x01,
+                NoiseHalfDeltaRising = 0x01,
+                NoiseCountLimitRising = 0x00,
+                FilterDelayCountLimitRising = 0x00,
+                MaxHalfDeltaFalling = 0x01,
+                NoiseHalfDeltaFalling = 0x01,
+                NoiseCountLimitFalling = 0xFF,
+                FilterDelayCountLimitFalling = 0x01,
+                ElectrodeTouchThreshold = 0x0F,
+                ElectrodeReleaseThreshold = 0x0A,
+                ChargeDischargeTimeConfiguration = 0x04,
+                ElectrodeConfiguration = 0x0C
+            };
+        }
+
+        private void InitializeController(Mpr121Configuration configuration)
+        {
+            SetRegister(Registers.MHDR, configuration.MaxHalfDeltaRising);
+            SetRegister(Registers.NHDR, configuration.NoiseHalfDeltaRising);
+            SetRegister(Registers.NCLR, configuration.NoiseCountLimitRising);
+            SetRegister(Registers.FDLR, configuration.FilterDelayCountLimitRising);
+            SetRegister(Registers.MHDF, configuration.MaxHalfDeltaFalling);
+            SetRegister(Registers.NHDF, configuration.NoiseHalfDeltaFalling);
+            SetRegister(Registers.NCLF, configuration.NoiseCountLimitFalling);
+            SetRegister(Registers.FDLF, configuration.FilterDelayCountLimitFalling);
+            SetRegister(Registers.E0TTH, configuration.ElectrodeTouchThreshold);
+            SetRegister(Registers.E0RTH, configuration.ElectrodeReleaseThreshold);
+            SetRegister(Registers.E1TTH, configuration.ElectrodeTouchThreshold);
+            SetRegister(Registers.E1RTH, configuration.ElectrodeReleaseThreshold);
+            SetRegister(Registers.E2TTH, configuration.ElectrodeTouchThreshold);
+            SetRegister(Registers.E2RTH, configuration.ElectrodeReleaseThreshold);
+            SetRegister(Registers.E3TTH, configuration.ElectrodeTouchThreshold);
+            SetRegister(Registers.E3RTH, configuration.ElectrodeReleaseThreshold);
+            SetRegister(Registers.E4TTH, configuration.ElectrodeTouchThreshold);
+            SetRegister(Registers.E4RTH, configuration.ElectrodeReleaseThreshold);
+            SetRegister(Registers.E5TTH, configuration.ElectrodeTouchThreshold);
+            SetRegister(Registers.E5RTH, configuration.ElectrodeReleaseThreshold);
+            SetRegister(Registers.E6TTH, configuration.ElectrodeTouchThreshold);
+            SetRegister(Registers.E6RTH, configuration.ElectrodeReleaseThreshold);
+            SetRegister(Registers.E7TTH, configuration.ElectrodeTouchThreshold);
+            SetRegister(Registers.E7RTH, configuration.ElectrodeReleaseThreshold);
+            SetRegister(Registers.E8TTH, configuration.ElectrodeTouchThreshold);
+            SetRegister(Registers.E8RTH, configuration.ElectrodeReleaseThreshold);
+            SetRegister(Registers.E9TTH, configuration.ElectrodeTouchThreshold);
+            SetRegister(Registers.E9RTH, configuration.ElectrodeReleaseThreshold);
+            SetRegister(Registers.E10TTH, configuration.ElectrodeTouchThreshold);
+            SetRegister(Registers.E10RTH, configuration.ElectrodeReleaseThreshold);
+            SetRegister(Registers.E11TTH, configuration.ElectrodeTouchThreshold);
+            SetRegister(Registers.E11RTH, configuration.ElectrodeReleaseThreshold);
+            SetRegister(Registers.CDTC, configuration.ChargeDischargeTimeConfiguration);
+            SetRegister(Registers.ELECONF, configuration.ElectrodeConfiguration);
+        }
+
+        /// <summary>
+        /// The callback function for timer to refresh channels statuses.
+        /// </summary>
+        private void RefreshChannelStatuses(object state)
+        {
+            RefreshChannelStatuses();
+        }
+
+        /// <summary>
+        /// Refresh the channel statuses.
+        /// </summary>
+        private void RefreshChannelStatuses()
+        {
+            // Pause the auto-refresh to prevent possible collisions.
+            var periodRefresh = PeriodRefresh;
+            PeriodRefresh = 0;
+
+            Span<byte> buffer = stackalloc byte[2];
+            _device.Read(buffer);
+
+            short rawStatus = BinaryPrimitives.ReadInt16LittleEndian(buffer);
+            bool isStatusChanged = false;
+            for (var i = 0; i < CHANNELS_NUMBER; i++)
+            {
+                bool status = ((1 << i) & rawStatus) > 0;
+                if (_statuses[(Channels)i] != status)
+                {
+                    _statuses[(Channels)i] = status;
+                    isStatusChanged = true;
+                }
+            }
+
+            if (isStatusChanged)
+            {
+                OnChannelStatusesChanged();
+            }
+
+            // Resume the auto-refresh.
+            PeriodRefresh = periodRefresh;
+        }
+
+        private void SetRegister(Registers register, byte value)
+        {
+            Span<byte> data = stackalloc byte[] { (byte)register, value };
+            _device.Write(data);
+        }
+
+        private void OnChannelStatusesChanged()
+        {
+            ChannelStatusesChanged?.Invoke(this, new ChannelStatusesChangedEventArgs(_statuses.ToImmutableDictionary()));
+        }
+    }
+}

src/devices/Mpr121/Mpr121.csproj

+<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="Channels.cs" />
+    <Compile Include="ChannelStatusesChangedEventArgs.cs" />
+    <Compile Include="Mpr121.cs" />
+    <Compile Include="Mpr121Configuration.cs" />
+    <Compile Include="Registers.cs" />
+    <None Include="README.md" />
+    <PackageReference Include="System.Device.Gpio" Version="0.1.0-prerelease*" />
+  </ItemGroup>
+
+</Project>

src/devices/Mpr121/Mpr121Configuration.cs

+// 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.
+
+namespace Iot.Device.Mpr121
+{
+    /// <summary>
+    /// Configuration for registers listed on datasheet page 8.
+    /// </summary>
+    public class Mpr121Configuration
+    {
+        /// <summary>
+        /// Determines the largest magnitude of variation to pass through the baseline filter (rising).
+        /// </summary>
+        public byte MaxHalfDeltaRising { get; set; }
+
+        /// <summary>
+        /// Determines the incremental change when non-noise drift is detected (rising).
+        /// </summary>
+        public byte NoiseHalfDeltaRising { get; set; }
+
+        /// <summary>
+        /// Determines the number of samples consecutively greater than the Max Half Delta value (rising).
+        /// This is necessary to determine that it is not noise. 
+        /// </summary>
+        public byte NoiseCountLimitRising { get; set; }
+
+        /// <summary>
+        /// Determines the operation rate of the filter. A larger count limit means the filter delay is operating more slowly (rising).
+        /// </summary>
+        public byte FilterDelayCountLimitRising { get; set; }
+
+        /// <summary>
+        /// Determines the largest magnitude of variation to pass through the baseline filter (falling).
+        /// </summary>
+        public byte MaxHalfDeltaFalling { get; set; }
+
+        /// <summary>
+        /// Determines the incremental change when non-noise drift is detected (falling).
+        /// </summary>
+        public byte NoiseHalfDeltaFalling { get; set; }
+
+        /// <summary>
+        /// Determines the number of samples consecutively greater than the Max Half Delta value (falling).
+        /// This is necessary to determine that it is not noise. 
+        /// </summary>
+        public byte NoiseCountLimitFalling { get; set; }
+
+        /// <summary>
+        /// Determines the operation rate of the filter. A larger count limit means the filter delay is operating more slowly (falling).
+        /// </summary>
+        public byte FilterDelayCountLimitFalling { get; set; }
+
+        /// <summary>
+        /// Electrode touch threshold.
+        /// </summary>
+        /// <remark>
+        /// Threshold settings are dependant on the touch/release signal strength, system sensitivity and noise immunity requirements.
+        /// In a typical touch detection application, threshold is typically in the range 0x04~0x10.
+        /// The touch threshold is several counts larger than the release threshold. This is to provide hysteresis and to prevent noise and jitter.
+        /// </remark>
+        public byte ElectrodeTouchThreshold { get; set; }
+
+        /// <summary>
+        /// Electrode release threshold.
+        /// </summary>
+        /// <remark>
+        /// Threshold settings are dependant on the touch/release signal strength, system sensitivity and noise immunity requirements.
+        /// In a typical touch detection application, threshold is typically in the range 0x04~0x10.
+        /// The touch threshold is several counts larger than the release threshold. This is to provide hysteresis and to prevent noise and jitter.
+        /// </remark>
+        public byte ElectrodeReleaseThreshold { get; set; }
+
+        /// <summary>
+        /// Filter/Global Charge Discharge Time Configuration (datasheet page 14).
+        /// </summary>
+        public byte ChargeDischargeTimeConfiguration { get; set; }
+
+        /// <summary>
+        /// Electrode Configuration (datasheet page 15).
+        /// </summary>
+        public byte ElectrodeConfiguration  { get; set; }
+    }
+}
\ No newline at end of file

src/devices/Mpr121/README.md

+# MPR121
+
+## Summary
+The 12-channels I2C proximity capacitive touch sensor controller.
+
+## Device Family
+
+**MPR121**: https://www.sparkfun.com/datasheets/Components/MPR121.pdf
+
+
+## Binding Notes
+
+The binding provides different options of device configuration. The device can be configured to update the channel statuses periodically. Also it supports custom configuration of controller registers.
+
+#### Default configuration with manually updating of channel statuses
+
+```csharp
+var i2cDevice = new UnixI2cDevice(new I2cConnectionSettings(busId: 1, deviceAddress: Mpr121.DefaultI2cAddress));
+var mpr121 = new Mpr121(device: i2cDevice);
+
+var statuses = mpr121.ReadChannelStatuses();
+var status = statuses[Channels.Channel01]
+    ? "pressed"
+    : "released";
+
+Console.WriteLine($"The 1st channel is {status}");
+```
+
+#### Channel statuses auto refresh
+
+```csharp
+var i2cDevice = new UnixI2cDevice(new I2cConnectionSettings(busId: 1, deviceAddress: Mpr121.DefaultI2cAddress));
+
+// Initialize controller with default configuration and auto-refresh the channel statuses every 100 ms.
+var mpr121 = new Mpr121(device: i2cDevice, periodRefresh: 100);
+
+// Subscribe to channel statuses updates.
+mpr121.ChannelStatusesChanged += (object sender, ChannelStatusesChangedEventArgs e) =>
+    {
+        var channelStatuses = e.ChannelStatuses;
+        // do something.
+    };
+```
+
+#### Custom MPR121 registers configuration
+
+```csharp
+var i2cDevice = new UnixI2cDevice(new I2cConnectionSettings(busId: 1, deviceAddress: Mpr121.DefaultI2cAddress));
+var config = new Mpr121Configuration
+{
+    MaxHalfDeltaRising = 0x01,
+    NoiseHalfDeltaRising = 0x01,
+    NoiseCountLimitRising = 0x00,
+    FilterDelayCountLimitRising = 0x00,
+    MaxHalfDeltaFalling = 0x01,
+    NoiseHalfDeltaFalling = 0x01,
+    NoiseCountLimitFalling = 0xFF,
+    FilterDelayCountLimitFalling = 0x01,
+    ElectrodeTouchThreshold = 0x0F,
+    ElectrodeReleaseThreshold = 0x0A,
+    ChargeDischargeTimeConfiguration = 0x04,
+    ElectrodeConfiguration = 0x0C
+};
+
+var mpr121 = new Mpr121(device: i2cDevice, configuration: config);
+```
\ No newline at end of file

src/devices/Mpr121/Registers.cs

+// 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.
+
+namespace Iot.Device.Mpr121
+{
+    // Registers of Mpr121. Please see datasheet page 8 for details.
+    internal enum Registers : byte
+    {
+        /// <summary>
+        /// MHD Rising.
+        /// </summary>
+        MHDR = 0x2B,
+
+        /// <summary>
+        /// NHD Amount Rising.
+        /// </summary>
+        NHDR = 0x2C,
+
+        /// <summary>
+        /// NCL Rising.
+        /// </summary>
+        NCLR = 0x2D,
+
+        /// <summary>
+        /// FDL Rising.
+        /// </summary>
+        FDLR = 0x2E,
+
+        /// <summary>
+        /// MHD Falling.
+        /// </summary>
+        MHDF = 0x2F,
+
+        /// <summary>
+        /// NHD Amount Falling.
+        /// </summary>
+        NHDF = 0x30,
+
+        /// <summary>
+        /// NCL Falling.
+        /// </summary>
+        NCLF = 0x31,
+
+        /// <summary>
+        /// FDL Falling.
+        /// </summary>
+        FDLF = 0x32,
+
+        /// <summary>
+        /// ELE0 Touch Threshold.
+        /// </summary>
+        E0TTH = 0x41,
+
+        /// <summary>
+        /// ELE0 Release Threshold.
+        /// </summary>
+        E0RTH = 0x42,
+
+        /// <summary>
+        /// ELE1 Touch Threshold.
+        /// </summary>
+        E1TTH = 0x43,
+
+        /// <summary>
+        /// ELE1 Release Threshold.
+        /// </summary>
+        E1RTH = 0x44,
+
+        /// <summary>
+        /// ELE2 Touch Threshold.
+        /// </summary>
+        E2TTH = 0x45,
+
+        /// <summary>
+        /// ELE2 Release Threshold.
+        /// </summary>
+        E2RTH = 0x46,
+
+        /// <summary>
+        /// ELE3 Touch Threshold.
+        /// </summary>
+        E3TTH = 0x47,
+
+        /// <summary>
+        /// ELE3 Release Threshold.
+        /// </summary>
+        E3RTH = 0x48,
+
+        /// <summary>
+        /// ELE4 Touch Threshold.
+        /// </summary>
+        E4TTH = 0x49,
+
+        /// <summary>
+        /// ELE4 Release Threshold.
+        /// </summary>
+        E4RTH = 0x4A,
+
+        /// <summary>
+        /// ELE5 Touch Threshold.
+        /// </summary>
+        E5TTH = 0x4B,
+
+        /// <summary>
+        /// ELE5 Release Threshold.
+        /// </summary>
+        E5RTH = 0x4C,
+
+        /// <summary>
+        /// ELE6 Touch Threshold.
+        /// </summary>
+        E6TTH = 0x4D,
+
+        /// <summary>
+        /// ELE6 Release Threshold.
+        /// </summary>
+        E6RTH = 0x4E,
+
+        /// <summary>
+        /// ELE7 Touch Threshold.
+        /// </summary>
+        E7TTH = 0x4F,
+
+        /// <summary>
+        /// ELE7 Release Threshold.
+        /// </summary>
+        E7RTH = 0x50,
+
+        /// <summary>
+        /// ELE8 Touch Threshold.
+        /// </summary>
+        E8TTH = 0x51,
+
+        /// <summary>
+        /// ELE8 Release Threshold.
+        /// </summary>
+        E8RTH = 0x52,
+
+        /// <summary>
+        /// ELE9 Touch Threshold.
+        /// </summary>
+        E9TTH = 0x53,
+
+        /// <summary>
+        /// ELE9 Release Threshold.
+        /// </summary>
+        E9RTH = 0x54,
+
+        /// <summary>
+        /// ELE10 Touch Threshold.
+        /// </summary>
+        E10TTH = 0x55,
+
+        /// <summary>
+        /// ELE10 Release Threshold.
+        /// </summary>
+        E10RTH = 0x56,
+
+        /// <summary>
+        /// 
+        /// </summary>
+        E11TTH = 0x57,
+
+        /// <summary>
+        /// ELE11 Touch Threshold.
+        /// </summary>
+        E11RTH = 0x58,
+
+        /// <summary>
+        /// ELE11 Release Threshold.
+        /// </summary>
+        CDTC = 0x5D,
+
+        /// <summary>
+        /// Electrode Configuration.
+        /// </summary>
+        ELECONF = 0x5E
+    }
+}
\ No newline at end of file

src/devices/Mpr121/samples/Mpr121.Sample.cs

+// 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.Device.I2c;
+using System.Device.I2c.Drivers;
+
+namespace Iot.Device.Mpr121.Samples
+{
+    class Program
+    {
+        static void Main(string[] args)
+        {
+            var i2cDevice = new UnixI2cDevice(new I2cConnectionSettings(busId: 1, deviceAddress: Mpr121.DefaultI2cAddress));
+
+            // Initialize controller with default configuration and auto-refresh the channel statuses every 100 ms.
+            var mpr121 = new Mpr121(device: i2cDevice, periodRefresh: 100);
+
+            Console.Clear();
+            Console.CursorVisible = false;
+
+            PrintChannelsTable();
+            Console.WriteLine("Press Enter to exit.");
+
+            // Subscribe to channel statuses updates.
+            mpr121.ChannelStatusesChanged += (object sender, ChannelStatusesChangedEventArgs e) =>
+                {
+                    var channelStatuses = e.ChannelStatuses;
+                    foreach (var channel in channelStatuses.Keys)
+                    {
+                        Console.SetCursorPosition(14, (int)channel * 2 + 1);
+                        Console.Write(channelStatuses[channel] ? "#" : " ");
+                    }
+                };
+
+            using (mpr121)
+            {
+                Console.ReadLine();
+                Console.Clear();
+                Console.CursorVisible = true;
+            }
+        }
+
+        private static void PrintChannelsTable()
+        {
+            Console.WriteLine("-----------------");
+
+            foreach (var channel in Enum.GetValues(typeof(Channels)))
+            {
+                Console.WriteLine("| " + Enum.GetName(typeof(Channels), channel) + " |   |");
+                Console.WriteLine("-----------------");
+            }
+        }
+    }
+}

src/devices/Mpr121/samples/Mpr121.Samples.csproj

+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>netcoreapp2.1</TargetFramework>
+    <LangVersion>latest</LangVersion>
+  </PropertyGroup>
+
+  <ItemGroup>
+  	<ProjectReference Include="../Mpr121.csproj" />
+  </ItemGroup>
+
+</Project>

src/devices/Mpr121/samples/README.md

+# MPR121 Sample
+
+This sample demonstrates how to read channel statuses using auto-refresh configuration.
+
+### Handling the channel statuses changes
+
+```csharp
+mpr121.ChannelStatusesChanged += (object sender, ChannelStatusesChangedEventArgs e) =>
+    {
+        var channelStatuses = e.ChannelStatuses;
+        // do something.
+    };
+```
+
+### Channel statuses table
+
+The following status means that the **channel 1** and **channel 3** are pressed:
+
+![](./ChannelStatuses.png)
\ No newline at end of file

src/devices/README.md

@@ -22,6 +22,7 @@ Our vision: the majority of .NET bindings are written completely in .NET languag
 * [MAX44009 -- Ambient Light Sensor](Max44009/README.md)
 * [Mcp23xxx -- I/O Expander](Mcp23xxx/README.md)
 * [Mcp3008 -- Analog-to-Digital Converter](Mcp3008/README.md)
+* [Mpr121 -- Proximity Capacitive Touch Sensor Controller](Mpr121/README.md)
 * [nRF24L01 -- Single chip 2.4 GHz Transceiver](Nrf24l01/README.md)
 * [Pca95x4 -- I2C GPIO Expander](Pca95x4/README.md)
 * [Pca9685 -- I2C PWM Driver](Pca9685/README.md)