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Software/CSharp/GrovePi/Sensors/DHTTemperatureAndHumiditySensor .cs

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+using System;
+using GrovePi.Common;
+
+namespace GrovePi.Sensors
+{
+    public interface IDHTTemperatureAndHumiditySensor
+    {
+        double TemperatureInCelsius { get; }
+        double TemperatureInFahrenheit { get; }
+        double Humidity { get; }
+        void Measure();
+    }
+
+    /// <summary>
+    /// Specifies the model of sensor. 
+    /// DHT11 - blue one - comes with the GrovePi+ Starter Kit.
+    /// DHT22 - white one, aka DHT Pro or AM2302.
+    /// DHT21 - black one, aka AM2301.
+    /// </summary>
+    public enum DHTModel
+    {
+        /* 
+        */
+        Dht11 = 0,
+        Dht21 = 1,
+        Dht22 = 2
+    }
+
+    internal class DHTTemperatureAndHumiditySensor : IDHTTemperatureAndHumiditySensor
+    {
+        private readonly GrovePi _device;
+        private readonly DHTModel _model;
+        private readonly Pin _pin;
+
+        private const byte DHTCmd = 40;
+
+        private double t = 0;
+        private double h = 0;
+
+        internal DHTTemperatureAndHumiditySensor(GrovePi device, Pin pin, DHTModel model)
+        {
+            if (device == null) throw new ArgumentNullException(nameof(device));
+            _device = device;
+            _pin = pin;
+            _model = model;
+        }
+
+        public void Measure()
+        {
+            _device.DirectAccess.WritePartial(new byte[4] { DHTCmd, (byte)_pin, (byte)_model, Constants.Unused });
+            Delay.Milliseconds(600);
+
+            var readBuffer = new byte[9];
+            _device.DirectAccess.ReadPartial(readBuffer);
+
+            float t0 = BitConverter.ToSingle(readBuffer, 1);
+            float h0 = BitConverter.ToSingle(readBuffer, 5);
+
+            t = (double)t0;
+            h = (double)h0;
+        }
+
+        private double CtoF(double c)
+        {
+            return c * 9 / 5 + 32;
+        }
+
+        public double TemperatureInCelsius
+        {
+            get
+            {
+                return t;
+            }
+        }
+
+        public double TemperatureInFahrenheit
+        {
+            get
+            {
+                return CtoF(t);
+            }
+        }
+
+        public double Humidity
+        {
+            get
+            {
+                return h;
+            }
+        }
+    }
+}