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using System;
using Windows.ApplicationModel.Background;
// Add using statements to the GrovePi libraries
using GrovePi;
using GrovePi.Sensors;
using GrovePi.I2CDevices;
using Windows.System.Threading;
using System.Text;
using System.Threading.Tasks;
using Microsoft.Azure.Devices.Client;
namespace ConnectedThingy
public sealed class StartupTask : IBackgroundTask
// Connect the buzzer to digital port 2
IBuzzer buzzer;
// Connect the button sensor to digital port 4
IButtonSensor button;
// Connect the Blue LED to digital port 5
ILed blueLed;
// Connect the Red LED to digital port 6
ILed redLed;
/**** ANALOG SENSORS ****/
// Connect the light sensor to analog port 2
ILightSensor lightSensor;
/**** I2C Deices ****/
// Connect the RGB display to one of the I2C ports
IRgbLcdDisplay display;
/**** Constants and Variables ****/
// Decide an a level of ambient light at which the LED should
// be in a completely off state (e.g. sensorValue == 700)
const int ambientLightThreshold = 700;
// Create a variable to track the current red LED brightness
private int brightness;
// Create a variable to track the current value from the Light Sensor
private int actualAmbientLight;
// Create a variable to track the state of the button
private SensorStatus buttonState;
// Create a timer to control the rateof sensor and actuator interactions
private ThreadPoolTimer timer;
// Create a deferral object to prevent the app from terminating
private BackgroundTaskDeferral deferral;
// Define the Azure IoT SDK DeviceClient instance
private DeviceClient deviceClient;
// Create a timer to control the rate of sending messages to Azure.
private ThreadPoolTimer messageTimer;
// Use the device specific connection string here
// Use the name of your Azure IoT device here - this should be the same as the name in the connections string
// Provide a short description of the location of the device, such as 'Home Office' or 'Garage'
public void Run(IBackgroundTaskInstance taskInstance)
// Get the deferral instance
deferral = taskInstance.GetDeferral();
// Instantiate the Azure device client
deviceClient = DeviceClient.CreateFromConnectionString(IOT_HUB_CONN_STRING);
// Instantiate the sensors and actuators
buzzer = DeviceFactory.Build.Buzzer(Pin.DigitalPin2);
button = DeviceFactory.Build.ButtonSensor(Pin.DigitalPin4);
blueLed = DeviceFactory.Build.Led(Pin.DigitalPin5);
redLed = DeviceFactory.Build.Led(Pin.DigitalPin6);
lightSensor = DeviceFactory.Build.LightSensor(Pin.AnalogPin2);
display = DeviceFactory.Build.RgbLcdDisplay();
buttonState = SensorStatus.Off;
// The IO to the GrovePi sensors and actuators can generate a lot
// of exceptions - wrap all GrovePi API calls in try/cath statements.
// Set the RGB backlight to red and display a message
display.SetBacklightRgb(255, 0, 0);
display.SetText("The Thingy is getting started");
catch (Exception ex)
// On Error, Resume Next :)
// Start a timer to check the sensors and activate the actuators five times per second
timer = ThreadPoolTimer.CreatePeriodicTimer(Timer_Tick, TimeSpan.FromMilliseconds(200));
// Send messages to Azure IoT Hub every one-second
// Start a timer to send messages to Azure once per second
messageTimer = ThreadPoolTimer.CreatePeriodicTimer(MessageTimer_Tick, TimeSpan.FromSeconds(1));
private void MessageTimer_Tick(ThreadPoolTimer timer)
SendMessageToIoTHubAsync("ambientLight", actualAmbientLight);
private async Task SendMessageToIoTHubAsync(string sensorType, int sensorState)
var payload = "{" +
"\"deviceId\":\"" + IOT_HUB_DEVICE + "\", " +
"\"location\":\"" + IOT_HUB_DEVICE_LOCATION + "\", " +
"\"sensorType\":\"" + sensorType + "\", " +
"\"sensorState\":" + sensorState + ", " +
"\"localTimestamp\":\"" + DateTime.Now.ToLocalTime() + "\"" +
var msg = new Message(Encoding.UTF8.GetBytes(payload));
System.Diagnostics.Debug.WriteLine("\t{0}> Sending message: [{1}]", DateTime.Now.ToLocalTime(), payload);
await deviceClient.SendEventAsync(msg);
catch (Exception ex)
System.Diagnostics.Debug.WriteLine("!!!! " + ex.Message);
private void Timer_Tick(ThreadPoolTimer timer)
// Check the button state
if (button.CurrentState != buttonState)
// Capture the button state
buttonState = button.CurrentState;
// Change the state of the blue LED
// Send a message to Azure indicating the state change
SendMessageToIoTHubAsync("led", (int)blueLed.CurrentState);
// Capture the current value from the Light Sensor
actualAmbientLight = lightSensor.SensorValue();
System.Diagnostics.Debug.WriteLine("R: " + lightSensor.Resistance());
// If the actual light measurement is lower than the defined threshold
// then define the LED brightness based on the delta between the actual
// ambient light and the threshold value
if (actualAmbientLight < ambientLightThreshold)
// Use a range mapping method to conver the difference between the
// actual ambient light and the threshold to a value between 0 and 255
// (the 8-bit range of the LED on D6 - a PWM pin).
// If actual ambient light is low, the differnce between it and the threshold will be
// high resulting in a high brightness value.
brightness = Map(ambientLightThreshold - actualAmbientLight, 0, ambientLightThreshold, 0, 255);
// If the actual ambient light value is above the threshold then
// the LED should be completely off. Set the brightness to 0
brightness = 0;
// AnalogWrite uses Pulse Width Modulation (PWM) to
// control the brightness of the digital LED on pin D6.
// Use the brightness value to control the brightness of the RGB LCD backlight
byte rgbVal = Convert.ToByte(brightness);
display.SetBacklightRgb(rgbVal, rgbVal, 255);
// Updae the RGB LCD with the light and sound levels
display.SetText(String.Format("Thingy\nLight: {0}", actualAmbientLight));
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());
// This Map function is based on the Arduino Map function
private int Map(int src, int in_min, int in_max, int out_min, int out_max)
return (src - in_min) * (out_max - out_min) / (in_max - in_min) + out_min;