Skip to content
Switch branches/tags

Name already in use

A tag already exists with the provided branch name. Many Git commands accept both tag and branch names, so creating this branch may cause unexpected behavior. Are you sure you want to create this branch?
Go to file
Cannot retrieve contributors at this time
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;
namespace Thingy
public sealed class StartupTask : IBackgroundTask
// Connect the button sensor 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;
public void Run(IBackgroundTaskInstance taskInstance)
// Get the deferral instance
deferral = taskInstance.GetDeferral();
// 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));
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
// Capture the current value from the Light Sensor
actualAmbientLight = lightSensor.SensorValue();
// Log the amount of resistance the light sensor is providing.
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;