Merge pull request #351 from WildernessLabs/feature/Nxp74HC4051

Feature/nxp74 hc4051

Source/Meadow.Foundation.Peripherals/ICs.IOExpanders.AnalogMux/Driver/AnalogInputMultiplexerBase.cs

@@ -0,0 +1,55 @@
+using Meadow.Hardware;
+
+namespace Meadow.Foundation.ICs.IOExpanders
+{
+    public abstract class AnalogInputMultiplexerBase : IAnalogInputMultiplexer
+    {
+        protected object SyncRoot { get; }  = new object();
+
+        /// <summary>
+        /// The port connected to the Enable pin of the mux (otherwise must be tied low)
+        /// </summary>
+        public IDigitalOutputPort? EnablePort { get; }
+
+        /// <summary>
+        /// The analog input connected to the Mux output pin (Z)
+        /// </summary>
+        public IAnalogInputPort Signal { get; }
+
+        public abstract void SetInputChannel(int channel);
+
+        internal AnalogInputMultiplexerBase(IAnalogInputPort signalPort, IDigitalOutputPort? enablePort)
+        {
+            Signal = signalPort;
+            EnablePort = enablePort;
+        }
+
+        /// <summary>
+        /// Enables the multiplexer (if an enable port was provided)
+        /// </summary>
+        public void Enable()
+        {
+            if (EnablePort != null)
+            {
+                lock (SyncRoot)
+                {
+                    EnablePort.State = false; // active low
+                }
+            }
+        }
+
+        /// <summary>
+        /// Disables the multiplexer (if an enable port was provided)
+        /// </summary>
+        public void Disable()
+        {
+            if (EnablePort != null)
+            {
+                lock (SyncRoot)
+                {
+                    EnablePort.State = true;
+                }
+            }
+        }
+    }
+}

Source/Meadow.Foundation.Peripherals/ICs.IOExpanders.AnalogMux/Driver/Drivers/Hp4067.cs

@@ -0,0 +1,19 @@
+using Meadow.Hardware;
+
+namespace Meadow.Foundation.ICs.IOExpanders
+{
+    /// <summary>
+    /// Represents an Ti HP4067 16-channel analog multiplexer.
+    /// </summary>
+    /// <remarks>This part is identical to the Nxp74HC4067</remarks>
+    public class Hp4067 : Nxp74HC4067
+    {
+        /// <summary>
+        /// Creates a new Hp4067 object
+        /// </summary>
+        public Hp4067(IAnalogInputPort z, IDigitalOutputPort s0, IDigitalOutputPort? s1 = null, IDigitalOutputPort? s2 = null, IDigitalOutputPort? s3 = null, IDigitalOutputPort? enable = null)
+            : base(z, s0, s1, s2, s3, enable)
+        {
+        }
+    }
+}

Source/Meadow.Foundation.Peripherals/ICs.IOExpanders.AnalogMux/Driver/Drivers/Nxp74HC4051.cs

@@ -0,0 +1,138 @@
+using Meadow.Hardware;
+using System;
+
+namespace Meadow.Foundation.ICs.IOExpanders
+{
+    /// <summary>
+    /// Represents an NXP 74HC4051 8-channel analog multiplexer
+    /// </summary>
+    public class Nxp74HC4051 : AnalogInputMultiplexerBase
+    {
+        /// <summary>
+        /// The port connected to the mux's S0 selection pin
+        /// </summary>
+        public IDigitalOutputPort S0 { get; }
+        /// <summary>
+        /// The port connected to the mux's S1 selection pin
+        /// </summary>
+        public IDigitalOutputPort? S1 { get; }
+        /// <summary>
+        /// The port connected to the mux's S2 selection pin
+        /// </summary>
+        public IDigitalOutputPort? S2 { get; }
+
+        /// <summary>
+        /// Creates a new Nxp74HC4051 object using the default parameters
+        /// </summary>
+        public Nxp74HC4051(IAnalogInputPort z, IDigitalOutputPort s0, IDigitalOutputPort? s1 = null, IDigitalOutputPort? s2 = null, IDigitalOutputPort? enable = null)
+            : base (z, enable)
+        {
+            S0 = s0;
+            S1 = s1;
+            S2 = s2;
+        }
+
+        /// <summary>
+        /// Sets the channel input (Y pin) that will be routed to the mux output (Z pin)
+        /// </summary>
+        /// <param name="channel"></param>
+        /// <exception cref="ArgumentOutOfRangeException"></exception>
+        public override void SetInputChannel(int channel)
+        {
+            if (channel < 0 || channel > 7) throw new ArgumentOutOfRangeException();
+
+            lock (SyncRoot)
+            {
+                var reenable = false;
+
+                if (EnablePort != null)
+                {
+                    if (EnablePort.State)
+                    {
+                        reenable = true;
+
+                        // disable before switching to prevent possible mis-routing
+
+                        Disable();
+                    }
+                }
+
+                /*
+                Truth Table
+                E   S2  S1  S0
+                --  --  --  --
+                L   L   L   L   Y0 to Z
+                L   L   L   H   Y1 to Z
+                L   L   H   L   Y2 to Z
+                L   L   H   H   Y3 to Z
+                L   H   L   L   Y4 to Z
+                L   H   L   H   Y5 to Z
+                L   H   H   L   Y6 to Z
+                L   H   H   H   Y7 to Z
+                H   X   X   X   switches of
+                */
+
+                switch (channel)
+                {
+                    case 0:
+                        S0.State = false;
+                        if (S1 != null) { S1.State = false; }
+                        if (S2 != null) { S2.State = false; }
+                        break;
+                    case 1:
+                        S0.State = true;
+                        if (S1 != null) { S1.State = false; }
+                        if (S2 != null) { S2.State = false; }
+                        break;
+                    case 2:
+                        if (S1 == null) throw new ArgumentException("You must have an S1 connected to access channels > 1");
+                        S0.State = false;
+                        S1.State = true;
+                        if (S2 != null) { S2.State = false; }
+                        break;
+                    case 3:
+                        if (S1 == null) throw new ArgumentException("You must have an S1 connected to access channels > 1");
+                        S0.State = true;
+                        S1.State = true;
+                        if (S2 != null) { S2.State = false; }
+                        break;
+                    case 4:
+                        if (S1 == null) throw new ArgumentException("You must have an S1 connected to access channels > 1");
+                        if (S2 == null) throw new ArgumentException("You must have an S2 connected to access channels > 3");
+                        S0.State = false;
+                        S1.State = false;
+                        S2.State = true;
+                        break;
+                    case 5:
+                        if (S1 == null) throw new ArgumentException("You must have an S1 connected to access channels > 1");
+                        if (S2 == null) throw new ArgumentException("You must have an S2 connected to access channels > 3");
+                        S0.State = true;
+                        S1.State = false;
+                        S2.State = true;
+                        break;
+                    case 6:
+                        if (S1 == null) throw new ArgumentException("You must have an S1 connected to access channels > 1");
+                        if (S2 == null) throw new ArgumentException("You must have an S2 connected to access channels > 3");
+                        S0.State = false;
+                        S1.State = true;
+                        S2.State = true;
+                        break;
+                    case 7:
+                        if (S1 == null) throw new ArgumentException("You must have an S1 connected to access channels > 1");
+                        if (S2 == null) throw new ArgumentException("You must have an S2 connected to access channels > 3");
+                        S0.State = true;
+                        S1.State = true;
+                        S2.State = true;
+                        break;
+
+                }
+
+                if (reenable)
+                {
+                    Enable();
+                }
+            }
+
+        }
+    }
+}