Reading data from Arduino Bluetooth on Windows Phone 8.1 - windows-phone-8

I am developing a code that will allow me to send small amounts of data between my arduino mega and my windows 8.1 phone using a HC-05 bluetooth module.
Sending data from the phone to the arduino was pretty simple, but I am having a dire time attempting to read data that comes back from the arduino that I send on the serial port.
For testing purposes my code is simple, sending ascii charaters 'a' & 'b' to turn an LED on & off, this could not work any better, but I am having trouble trying to figure out how to correctly read the data that I send back to my phone.
I send a single arbitrary ascii character back to the phone but I cannot for the life of me figure out the correct way of reading this data from the bluetooth stream I have setup.
I have been trying for nearly two days, but everything I try ends up freezing my phone with no exceptions thrown? A lot of posts online send me to the Nokia dev site which is now inactive.
I have tried using the 'datareader' and the 'streamreader' classes to do this but it always freezes, does anyone know how to make this work? And why my streamreader keeps freezing my phone?
I have tried to annotate my code appropriatley (seen below). The problem occurs in the 'Tick' event handler at the bottom of the code.
(FYI: All capabilities have been added to the manifest files so this shouldn't be the problem).
Thank you.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Navigation;
using Microsoft.Phone.Controls;
using Microsoft.Phone.Shell;
using Bluetooth_SL.Resources;
using Windows.Networking;
using Windows.Networking.Proximity;
using Windows.Networking.Sockets;
using Windows.Devices.Bluetooth;
using System.IO;
using Microsoft.Xna.Framework;
using System.Windows.Threading;
using Windows.Storage.Streams; // <-- for the datareader class
namespace Bluetooth_SL // silverlight, does this matter?
{
public partial class MainPage : PhoneApplicationPage
{
DispatcherTimer Timer = new DispatcherTimer();
StreamSocket socket = new StreamSocket();
StreamWriter writer;
StreamReader reader;
public MainPage()
{
InitializeComponent();
Timer.Interval = TimeSpan.FromMilliseconds(1000); // dispatcher timer used to check for incoming data from arduino
Timer.Tick += Timer_Tick; // event handler for dispatcher timer
}
protected override void OnNavigatedFrom(NavigationEventArgs e) // frees up memory
{
socket.Dispose();
}
private void Connect_But_Tap(object sender, System.Windows.Input.GestureEventArgs e)
{
ConnectToBluetooth();
}
private async void ConnectToBluetooth() // sets up the connection // this works fine
{
// Configure PeerFinder to search for all paired devices.
PeerFinder.AlternateIdentities["Bluetooth:Paired"] = "";
var pairedDevices = await PeerFinder.FindAllPeersAsync();
if (pairedDevices.Count == 0)
{
Debug_Block.Text = "No paired devices were found.";
}
else
{
Debug_Block.Text = "Found";
PeerInformation selectedDevice = pairedDevices[0]; // pick the first paired device
try // 'try' used in the case the socket has already been connected
{
await socket.ConnectAsync(selectedDevice.HostName, "1");
writer = new StreamWriter(socket.OutputStream.AsStreamForWrite());
writer.AutoFlush = true;
reader = new StreamReader(socket.InputStream.AsStreamForRead());
Debug_Block.Text = "Connected";
}
catch (Exception x)
{
Debug_Block.Text = x.ToString();
}
}
}
private void SendButton_Tap(object sender, System.Windows.Input.GestureEventArgs e) // this works perfectly
{
try { writer.WriteLine("a"); } // attempts to write the ascii 'a' to the arduino which turns on the on-board LED
catch { Debug_Block.Text = "Failed to write"; }
}
private void SendButton_Off_Tap(object sender, System.Windows.Input.GestureEventArgs e) // this works perfectly
{
try { writer.WriteLine("b"); } // attempts to write the ascii 'b' to the arduino which turns off the on-board LED
catch { Debug_Block.Text = "Failed to write"; }
}
private void ReadButtonToggle_Tap(object sender, System.Windows.Input.GestureEventArgs e) // toggles the timer on and off
{
if(Timer.IsEnabled == true)
{
Timer.Stop();
Debug_Block.Text = "Timer Stopped";
}
else
{
Timer.Start();
Debug_Block.Text = "Timer Started";
}
}
void Timer_Tick(object sender, EventArgs e) // THIS IS THE PROBLEM
{
Debug_Block.Text = "Tick";
Debug_Block.Text = reader.ReadLine(); // <-- ALWAYS FREEZES HERE
Timer.Stop(); // This line is temporary for debugging
}
}
}

Related

Exception When Rendering an Image Using Lumia Imaging SDK

In my WP8.1 app, I'm trying to crop an image using the Lumia (formerly Nokia) Imaging SDK. the image is retrieved using FileOpenPicker:
public async void ContinueFileOpenPicker(Windows.ApplicationModel.Activation.FileOpenPickerContinuationEventArgs args) {
if (args.Files.Count > 0) {
_stream = await args.Files[0].OpenAsync(Windows.Storage.FileAccessMode.Read);
_bitmapImage = new Windows.UI.Xaml.Media.Imaging.BitmapImage();
await _bitmapImage.SetSourceAsync(_stream);
SelectedImage.Source = _bitmapImage;
}
else {
Debug.WriteLine("Operation cancelled.");
}
}
Then the filter applied in a button handler (after the user selected a cropping area; dimensions just for testing purposes):
private async void GetImageAcceptButton_Click(object sender, RoutedEventArgs e) {
await GetCroppedBitmapAsync();
}
async public Task GetCroppedBitmapAsync() {
using (var source = new RandomAccessStreamImageSource(_stream)) {
using (var filterEffect = new FilterEffect(source)) {
var filter = new CropFilter(new Windows.Foundation.Rect(0, 0, 100, 100));
filterEffect.Filters = new IFilter[] { filter };
var target = new WriteableBitmap(50, 50);
using (var renderer = new WriteableBitmapRenderer(filterEffect, target)) {
await renderer.RenderAsync();
SelectedImage.Source = target;
}
}
}
}
The RenderAsync() call throws an exception:
System.Runtime.InteropServices.COMException occurred
HResult=-2147467259
Message=Error HRESULT E_FAIL has been returned from a call to a COM component.
Source=mscorlib
ErrorCode=-2147467259
Applying the filters seems rather straightforward. Why does it fail here?
You should enable native debugging and look at the Output window. You're currently missing the real exception message (which tries to be more specific). Exception message strings are "smuggled" across the WinRT call border, only an HRESULT is officially passed (here, E_FAIL).
Is this Silverlight 8.1 or a Universal App btw?
My guess at an answer might be that you need to seek/rewind the stream back. It could be that the position is at the end.

CameraPreviewImageSource empty preview frame

I made cut and paste of the code below about how to use CameraPreviewImageSource and access to preview buffer frames, but do not work and it seems the frame buffer size is 0x0 reading the value of IImageSize parameter of OnPreviewFrameAvailable event.
How to get preview buffer of MediaCapture - Universal app
protected override void OnNavigatedTo(NavigationEventArgs e)
{
InitializeAsync();
}
public async void InitializeAsync()
{
_cameraPreviewImageSource = new CameraPreviewImageSource();
await _cameraPreviewImageSource.InitializeAsync(string.Empty);
var properties = await _cameraPreviewImageSource.StartPreviewAsync();
var width = 640.0;
var height = 480;
_writeableBitmap = new WriteableBitmap((int)width, (int)height);
_writeableBitmapRenderer = new WriteableBitmapRenderer(_cameraPreviewImageSource, _writeableBitmap);
Initialized = true;
_cameraPreviewImageSource.PreviewFrameAvailable += OnPreviewFrameAvailable;
}
private async void OnPreviewFrameAvailable(IImageSize args)
{
System.Diagnostics.Debug.WriteLine("ww:"+args.Size.Width+" hh:"+args.Size.Height);
// Prevent multiple rendering attempts at once
if (Initialized && !_isRendering)
{
_isRendering = true;
try
{
await _writeableBitmapRenderer.RenderAsync();
}
catch (Exception ex)
{
System.Diagnostics.Debug.WriteLine("\n\n"+ex.Message);
System.Diagnostics.Debug.WriteLine(ex.StackTrace);
}
_isRendering = false;
}
}
Capabilities (webcam & microphone) on Package.appxmanifest has been selected
Implementing CameraPreviewImageSource on a Silverlight app works great!
I am afraid you are (were) seeing a bug in Lumia Imaging SDK 2.0.184. The problem only occured on some camera models and only on 8.1/universal applications. Silverlight applications were not affected by the problem.
The bug has been fixed in the newly released Lumia Imaging SDK 2.0.208. From release notes:
Fixed ArgumentOutOfRangeException being thrown by CameraPreviewImageSource when used with certain camera models.

Wait until async operation ends Windows Phone

I am trying to parse some pois from a xml download from a server and I saw that it is done after the program continues in the main thread. I haven't found a way to solve it because I need it.
using System.Threading;
namespace XML_Parser
{
class XMLParserPOI_Wiki
{
private static XMLParserPOI_Wiki objSingle = new XMLParserPOI_Wiki();
public static XMLParserPOI_Wiki ObjSingle
{
get { return objSingle; }
set { objSingle = value; }
}
private List<POI> places;
public List<POI> Places
{
get { return places; }
}
private XMLParserPOI_Wiki()
{
}
public void parseWikitude(string url)
{
places = new List<POI>();
WebClient wc = new WebClient();
wc.DownloadStringCompleted += HttpsCompleted;
wc.DownloadStringAsync(new Uri(url));
}
private void HttpsCompleted(object sender, DownloadStringCompletedEventArgs e)
{
if (e.Error == null)
{
XDocument xdoc = XDocument.Parse(e.Result, LoadOptions.None);
XNamespace ns = "http://www.opengis.net/kml/2.2";
XNamespace ns2 = "http://www.openarml.org/wikitude/1.0";
var placemarkers = xdoc.Root.Descendants(ns + "Placemark");
places =
(from query in xdoc.Root.Descendants(ns + "Placemark")
select new POI
(
...
)).ToList();
System.Diagnostics.Debug.WriteLine("Lista");
System.Diagnostics.Debug.WriteLine(places.Count);
}
}
}
}
In my main class:
XMLParserPOI_Wiki parserXML = XMLParserPOI_Wiki.ObjSingle;
parserXML.parseWikitude("http://myurl.php");
System.Diagnostics.Debug.WriteLine("Lista de pois");
System.Diagnostics.Debug.WriteLine(parserXML.Places.Count);
for (int i = 0; i < parserXML.Places.Count; i++)
{
System.Diagnostics.Debug.WriteLine(parserXML.Places[i].getName());
}
It prints Lista de POis and 0, before Lista and X (number of pois)
I guess I should freeze main thread but I tried a couple of times with some examples and they didn't work.
Can you point me to any tutorial about this? More than get an answer I want to understand how to deal with this kind of operations
First of all, you don't want to block (freeze) the UI thread EVER!
This is called asynchronous programming. There are two things you can do to solve your problem (I recommend option 2!):
Use the classic callback model. You basically call some long operation on a background thread and give a function to it, to execute when the long operation is done. Here's how to do it in your case.
At the end of the HttpsCompleted method, invoke what you need on the UI Thread using:
Deployment.Current.Dispatcher.BeginInvoke(delegate() {
//The code here will be invoked on the UI thread
});
If you want to make the parseWikitude method reusable, you should pass an Action to it. This way you can call it from multiple places and tell it what to do on the UI thread when the parsing is done. Something like this:
public void parseWikitude(string url, Action callback) {
places = new List<POI>();
WebClient wc = new WebClient();
wc.DownloadStringCompleted += HttpsCompleted;
wc.DownloadStringAsync(new Uri(url), callback);
}
private void HttpsCompleted(object sender, DownloadStringCompletedEventArgs e)
{
if (e.Error == null)
{
...
var callback = (Action)e.UserState;
Deployment.Current.Dispatcher.BeginInvoke(callback);
}
}
//And then when you use it, you do it like that
parserXML.parseWikitude("http://myurl.php", delegate() {
//The code here will be executed on the UI thread, after the parsing is done
});
Use the (rather) new asnyc pattern in .NET. You should read about this, as it is one of the best features of .NET if you ask me. :) It basically does the callback thing automatically and makes the code a lot easier to read/maintain/work-with. Once you get used to it, that is.
Here's an example:
public Task<List<POI>> parseWikitude(string url) {
TaskCompletionSource<List<POI>> resultTaskSource = new TaskCompletionSource<List<POI>>();
WebClient wc = new WebClient();
wc.DownloadStringCompleted += HttpsCompleted;
wc.DownloadStringAsync(new Uri(url), resultTaskSource);
return resultTaskSource.Task;
}
private void HttpsCompleted(object sender, DownloadStringCompletedEventArgs e)
{
if (e.Error == null)
{
//If needed, run the code here in a background thread
//...
var resultTaskSource = (TaskCompletionSource<List<POI>>)e.UserState;
resultTaskSource.SetResult(places);
}
}
//And when you need to use it, do it like that (note, this must be invoked in an async method!)
var places = await parser.parseWikitude("http://myurl.php");
//The code here will be executed on the same thread when the parsing is done, but the thread will not be blocked while the download is happening.
So, these are the two ways you can handle it. Option one is old-school, classic and easy. Option two is the new and cool way of doing async stuff. It really is a must-know. Simplifies a lot of things once you get used to it.
P.S. Sorry if I got carried away. :D

windows phone 8: how to download xml file from web and save it to local?

I would like to download a xml file from web, then save it to the local storage but I do not know how to do that. Please to help me clearly or give me an example. Thank you.
Downloading a file is a huge subject and can be done in many ways. I assume that you know the Uri of the file you want to download, and want you mean by local is IsolatedStorage.
I'll show three examples how it can be done (there are also other ways).
1. The simpliest example will dowload string via WebClient:
public static void DownloadFileVerySimle(Uri fileAdress, string fileName)
{
WebClient client = new WebClient();
client.DownloadStringCompleted += (s, ev) =>
{
using (IsolatedStorageFile ISF = IsolatedStorageFile.GetUserStoreForApplication())
using (StreamWriter writeToFile = new StreamWriter(ISF.CreateFile(fileName)))
writeToFile.Write(ev.Result);
};
client.DownloadStringAsync(fileAdress);
}
As you can see I'm directly downloading string (ev.Result is a string - that is a disadventage of this method) to IsolatedStorage.
And usage - for example after Button click:
private void Download_Click(object sender, RoutedEventArgs e)
{
DownloadFileVerySimle(new Uri(#"http://filedress/myfile.txt", UriKind.Absolute), "myfile.txt");
}
2. In the second method (simple but more complicated) I'll use again WebClient and I'll need to do it asynchronously (if you are new to this I would suggest to read MSDN, async-await on Stephen Cleary blog and maybe some tutorials).
First I need Task which will download a Stream from web:
public static Task<Stream> DownloadStream(Uri url)
{
TaskCompletionSource<Stream> tcs = new TaskCompletionSource<Stream>();
WebClient wbc = new WebClient();
wbc.OpenReadCompleted += (s, e) =>
{
if (e.Error != null) tcs.TrySetException(e.Error);
else if (e.Cancelled) tcs.TrySetCanceled();
else tcs.TrySetResult(e.Result);
};
wbc.OpenReadAsync(url);
return tcs.Task;
}
Then I'll write my method downloading a file - it also need to be async as I'll use await DownloadStream:
public enum DownloadStatus { Ok, Error };
public static async Task<DownloadStatus> DownloadFileSimle(Uri fileAdress, string fileName)
{
try
{
using (Stream resopnse = await DownloadStream(new Uri(#"http://filedress/myfile.txt", UriKind.Absolute)))
using (IsolatedStorageFile ISF = IsolatedStorageFile.GetUserStoreForApplication())
{
if (ISF.FileExists(fileName)) return DownloadStatus.Error;
using (IsolatedStorageFileStream file = ISF.CreateFile(fileName))
resopnse.CopyTo(file, 1024);
return DownloadStatus.Ok;
}
}
catch { return DownloadStatus.Error; }
}
And usage of my method for example after Button click:
private async void Downlaod_Click(object sender, RoutedEventArgs e)
{
DownloadStatus fileDownloaded = await DownloadFileSimle(new Uri(#"http://filedress/myfile.txt", UriKind.Absolute), "myfile.txt");
switch (fileDownloaded)
{
case DownloadStatus.Ok:
MessageBox.Show("File downloaded!");
break;
case DownloadStatus.Error:
default:
MessageBox.Show("There was an error while downloading.");
break;
}
}
This method can have problems for example if you try to download very big file (example 150 Mb).
3. The third method - uses WebRequest with again async-await, but this method can be changed to download files via buffer, and therefore not to use too much memory:
First I'll need to extend my Webrequest by a method that will asynchronously return a Stream:
public static class Extensions
{
public static Task<Stream> GetRequestStreamAsync(this WebRequest webRequest)
{
TaskCompletionSource<Stream> taskComplete = new TaskCompletionSource<Stream>();
webRequest.BeginGetRequestStream(arg =>
{
try
{
Stream requestStream = webRequest.EndGetRequestStream(arg);
taskComplete.TrySetResult(requestStream);
}
catch (Exception ex) { taskComplete.SetException(ex); }
}, webRequest);
return taskComplete.Task;
}
}
Then I can get to work and write my Downloading method:
public static async Task<DownloadStatus> DownloadFile(Uri fileAdress, string fileName)
{
try
{
WebRequest request = WebRequest.Create(fileAdress);
if (request != null)
{
using (Stream resopnse = await request.GetRequestStreamAsync())
{
using (IsolatedStorageFile ISF = IsolatedStorageFile.GetUserStoreForApplication())
{
if (ISF.FileExists(fileName)) return DownloadStatus.Error;
using (IsolatedStorageFileStream file = ISF.CreateFile(fileName))
{
const int BUFFER_SIZE = 10 * 1024;
byte[] buf = new byte[BUFFER_SIZE];
int bytesread = 0;
while ((bytesread = await resopnse.ReadAsync(buf, 0, BUFFER_SIZE)) > 0)
file.Write(buf, 0, bytesread);
}
}
return DownloadStatus.Ok;
}
}
return DownloadStatus.Error;
}
catch { return DownloadStatus.Error; }
}
Again usage:
private async void Downlaod_Click(object sender, RoutedEventArgs e)
{
DownloadStatus fileDownloaded = await DownloadFile(new Uri(#"http://filedress/myfile.txt", UriKind.Absolute), "myfile.txt");
switch (fileDownloaded)
{
case DownloadStatus.Ok:
MessageBox.Show("File downloaded!");
break;
case DownloadStatus.Error:
default:
MessageBox.Show("There was an error while downloading.");
break;
}
}
Those methods of course can be improved but I think this can give you an overview how it can look like. The main disadvantage of these methods may be that they work in foreground, which means that when you exit your App or hit start button, downloading stops. If you need to download in background you can use Background File Transfers - but that is other story.
As you can see you can reach your goal in many ways. You can read more about those methods on many pages, tutorials and blogs, compare an choose the most suitable.
Hope this helps. Happy coding and good luck.

Infinite wait loading remote image into BitmapImage() in Background Agent

I have a valid URL for a remote JPEG which I'm trying to load in the background. But I find I never get control back after invoking the BitmapImage() constructor. My question is, should this approach work, or should I pitch it all, load up BcpAsync project from NuGet and start working with WebClient asynch methods?
A sample URL for which it fails is
http://image.weather.com/images/maps/current/garden_june_720x486.jpg
It is valid. .UpdateAsync() references it from AppViewModel.Instance, it's not explicitly referenced here.
Here's the background agent:
protected override async void OnInvoke(ScheduledTask task)
{
AppViewModel.LoadData();
await AppViewModel.Instance.RemoteImageProxy.UpdateAsync();
AppViewModel.Instance.ImageUrl = AppViewModel.Instance.RemoteImageProxy.LocalFileUri;
AppViewModel.Instance.UpdateCount++;
PinnedTile.Update();
}
AppViewModel.SaveData();
#if DEBUG
ScheduledActionService.LaunchForTest(task.Name, TimeSpan.FromSeconds(AppViewModel.Instance.BgAgentInterval));
#endif
NotifyComplete();
}
Here's the invoked method:
public Task<double> UpdateAsync() {
LastCheckedTime = DateTime.UtcNow;
CompletionTask = new TaskCompletionSource<double>();
// Not usually called on UI thread, not worth optimizing for that case here.
Deployment.Current.Dispatcher.BeginInvoke(() => { //todo determine whether System.Windows.Deployment.Dispatcher can be called from main app, or just bgAgent.
HelperImageControl = new Image();
HelperImageControl.Loaded += im_Loaded;
HelperImageControl.ImageFailed += im_ImageFailed;
HelperImageControl.ImageOpened += im_ImageOpened;
// breakpoint here
HelperImageControl.Source = new BitmapImage(SourceUri);
// stepping over the function, control does not return here. Nor are any of the above events fired.
});
return CompletionTask.Task; // this will be completed in one of the subsequent control events...
}
You need to call CompletionTask.SetResult(); to return control back to the caller method.
This works (I'm returning 100 in case of successful download because you set the task to return double).
TaskCompletionSource<double> CompletionTask;
public Task<double> UpdateAsync()
{
CompletionTask = new TaskCompletionSource<double>();
Deployment.Current.Dispatcher.BeginInvoke(() =>
{
var HelperImageControl = new Image();
var bmp = new BitmapImage();
bmp.ImageOpened += bmp_ImageOpened;
bmp.ImageFailed += bmp_ImageFailed;
bmp.CreateOptions = BitmapCreateOptions.None;
bmp.UriSource = new Uri("http://image.weather.com/images/maps/current/garden_june_720x486.jpg", UriKind.Absolute);
HelperImageControl.Source = bmp;
});
return CompletionTask.Task;
}
void bmp_ImageFailed(object sender, ExceptionRoutedEventArgs e)
{
CompletionTask.SetException(e.ErrorException);
}
void bmp_ImageOpened(object sender, RoutedEventArgs e)
{
CompletionTask.SetResult(100);
}