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Software/CSharp/Samples/LedFade/StartupTask.cs

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+// Adjust LED brightness by rotating Potentiometer
+
+// GrovePi + Rotary Angle Sensor (Potentiometer) + LED
+// http://www.seeedstudio.com/wiki/Grove_-_Rotary_Angle_Sensor
+// http://www.seeedstudio.com/wiki/Grove_-_LED_Socket_Kit
+
+/*
+The MIT License(MIT)
+
+GrovePi for the Raspberry Pi: an open source platform for connecting Grove Sensors to the Raspberry Pi.
+Copyright (C) 2017  Dexter Industries
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.
+*/
+
+using System;
+using Windows.ApplicationModel.Background;
+
+// Add using statements to the GrovePi libraries
+using GrovePi;
+using GrovePi.Sensors;
+
+namespace LedFade
+{
+    public sealed class StartupTask : IBackgroundTask
+    {
+        public void Run(IBackgroundTaskInstance taskInstance)
+        {
+            // Connect the Rotary Angle Sensor to analog port 2
+            IRotaryAngleSensor potentiometer = DeviceFactory.Build.RotaryAngleSensor(Pin.AnalogPin2);
+
+            // Connect the LED to digital port 5
+            ILed led = DeviceFactory.Build.Led(Pin.DigitalPin5);
+
+            // Create a variable to track the LED brightness
+            double brightness = 0;
+
+            // Capture the current value from the Rotary Angle sensor
+            double angle = 0;
+
+            // Loop endlessly
+            while (true)
+            {
+                try
+                {
+                    // Capture the current value from the Rotary Angle sensor
+                    angle = potentiometer.SensorValue();
+
+                    // Output the agle to the Output Window
+                    System.Diagnostics.Debug.WriteLine("Angle is " + angle.ToString());
+
+                    // If the Rotary Angle sensor value is greater than zero...
+                    if (angle > 0)
+                    {
+                        // Divide the angle (a 10-bit value from 0-1023) by four
+                        // to get a single byte value value from 0-255.
+                        brightness = Math.Floor(angle / 4);
+                    }
+                    else
+                    {
+                        // If the angle is zero, set the brightness to zero
+                        brightness = 0;
+                    }
+
+                    // Output the brightness to the Output Window
+                    System.Diagnostics.Debug.WriteLine("Brightness is " + brightness.ToString());
+
+                    // AnalogWrite uses Pulse WIdth Modulation (PWM) to 
+                    // control the brightness of the digital LED.
+                    led.AnalogWrite(Convert.ToByte(brightness));
+                }
+                catch (Exception ex)
+                {
+                    // NOTE: There are frequent exceptions of the following:
+                    // WinRT information: Unexpected number of bytes was transferred. Expected: '. Actual: '.
+                    // This appears to be caused by the rapid frequency of writes to the GPIO
+                    // These are being swallowed here/
+
+                    // If you want to see the exceptions uncomment the following:
+                    // System.Diagnostics.Debug.WriteLine(ex.ToString());
+                }
+            }
+        }
+    }
+}