Everything about my daily life as a programmer/Electrical Engineer!

Twitter->SL4->Arduino Light Controller

This is a preliminary post about a new project I just finished (a variation of CoffeeTrack). I wanted to test the new capabilities of Silverlight 4 and push the boundaries of what people think of as a web application.  I made a point to not have a server portion of my application.  This application only requires SL4 and a COM library (trying to avoid).

I wanted to be able to control my lights from the internet.  This system takes twitter posts (now possible in SL4) and interprets them as commands and commands the Arduino via COM automation. Once a command is received the web cam snaps a photo and posts that to twitter to confirm the results.

The Arduino code is DEAD simple. The Arduino is linked to a wireless light controller found at Walmart for $10. I found one online that is similar.  I used relays to close the switches.

image

const int ledPin1 = 13; // the pin that the LED is attached to
const int ledPin2 = 12; // the pin that the LED is attached to

int incomingByte;      // a variable to read incoming serial data into

void setup() {
  // initialize serial communication:
  Serial.begin(9600);
  // initialize the LED pin as an output:
  pinMode(ledPin1, OUTPUT);
  pinMode(ledPin2, OUTPUT);
}

void loop() {
  // see if there's incoming serial data:
  if (Serial.available() > 0)
  {
    // read the oldest byte in the serial buffer:
    incomingByte = Serial.read();
   Serial.println((char)incomingByte);
   if (incomingByte == '0') {
      digitalWrite(ledPin1, HIGH);
      delay(1000);
      digitalWrite(ledPin1, LOW);
      Serial.println("Lights are off");
    }
    else if (incomingByte == '1') {
      digitalWrite(ledPin2, HIGH);
      delay(1000);
      digitalWrite(ledPin2, LOW);
      Serial.println("Lights are on!");
    }
  }
}

 

The Silverlight 4 code is a combination of many, many different libraries. I was able to successfully talk to twitter as long as I ran as an out of browser application (dumb client access policy).  I used the FJCore library to encode images to Jpeg. Special thanks to VisiFire for some helpful code using FJCore. I spent about 3 days working with the code from this post (which works in a Console App).  Once I figured out how the encodings worked I was able to update a photo on twitter via Silverlight.  The rest of the code I stole from CoffeeTrack (stay tuned!).

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Shapes;
using System.IO;
using System.Xml.Linq;
using System.Text;
using System.Threading;
using System.Windows.Threading;
using System.Net.Browser;
using System.Windows.Media.Imaging;
using FluxJpeg.Core.Encoder;
using FluxJpeg.Core;

namespace XmasLightController
{
public partial class MainPage : UserControl
{
DispatcherTimer t = new DispatcherTimer() { Interval = new TimeSpan(0, 1, 0) };
byte[] currentImage = null;
string value = "";
public MainPage()
{
InitializeComponent();
t.Tick += new EventHandler(t_Tick);
//t.Start();
MakeRequest();
//UpdateTwitterImage();

}

void t_Tick(object sender, EventArgs e)
{
MakeRequest();

}


private void MakeRequest()
{
HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create(new Uri("http://twitter.com/statuses/user_timeline/uwstephens.atom?&count=1"));
request.BeginGetResponse(new AsyncCallback(ReadCallback), request);
WriteText("Contacting twitter");
}


int currentcommand = 0;


private void ReadCallback(IAsyncResult asynchronousResult)
{
this.Dispatcher.BeginInvoke(delegate()
{
t.Stop();

});
WriteText("Recieved response from twitter");
HttpWebRequest request = (HttpWebRequest)asynchronousResult.AsyncState;
HttpWebResponse response = (HttpWebResponse)request.EndGetResponse(asynchronousResult);
using (StreamReader streamReader1 = new StreamReader(response.GetResponseStream()))
{

string resultString = streamReader1.ReadToEnd();
XDocument doc = XDocument.Parse(resultString, LoadOptions.SetBaseUri | LoadOptions.SetLineInfo);
List<XElement> elems = doc.Elements("entry").ToList();
StringBuilder sb = new StringBuilder();
int oldcommand = currentcommand;
foreach (var a in doc.Descendants().ToList())
{
if (a.Name.LocalName == "entry")
{
if(value!=a.Value)
{
UpdateTwitterImage();
}
value=a.Value;
if (a.Value.ToLower().Contains("action"))
{
currentcommand = 1;
}
else if (a.Value.ToLower().Contains("cut"))
{
currentcommand = 2;
}
else if (a.Value.ToLower().Contains("snap"))
{
currentcommand = 3;
}
}
}

this.Dispatcher.BeginInvoke(delegate()
{
if (currentcommand == 1)
{
WriteText("Start command received");

input.Text = "1";
SendMessage();
UpdateTwitterImage();

}
else if (currentcommand == 2)
{
WriteText("Stop command received");
input.Text = "0";
SendMessage();
UpdateTwitterImage();

}

});

this.Dispatcher.BeginInvoke(delegate()
{
t.Start();
});

}

}

public void WriteText(string txt)
{
this.Dispatcher.BeginInvoke(delegate() { this.outputWindow.Text += Environment.NewLine + txt; });
}

public void UpdateTwitterImage()
{
WriteText("Updating image");
if (currentImage == null) { return; }
String avatarUrl = "http://twitter.com/account/update_profile_image.xml";
String file = "xmas";
string imageType = "png";
WebRequest.RegisterPrefix("http://", System.Net.Browser.WebRequestCreator.ClientHttp);
string contentBoundaryBase = DateTime.Now.Ticks.ToString("x");
string beginContentBoundary = string.Format("--{0}\r\n", contentBoundaryBase);
var contentDisposition = string.Format("Content-Disposition:form-data); name=\"image\"); filename=\"{0}\"\r\nContent-Type: image/{1}\r\n\r\n", file, imageType);
var endContentBoundary = string.Format("\r\n--{0}--\r\n", contentBoundaryBase);

byte[] fileBytes = null;
Encoding encoding = Encoding.UTF8;

MemoryStream test = new MemoryStream();
byte[] data = encoding.GetBytes(beginContentBoundary);
test.Write(data, 0, data.Length);
data = encoding.GetBytes(contentDisposition);
test.Write(data, 0, data.Length);
data = currentImage;
test.Write(data, 0, data.Length);
data = encoding.GetBytes(endContentBoundary);
test.Write(data, 0, data.Length);
fileBytes = test.GetBuffer();

var req = (HttpWebRequest)HttpWebRequest.Create(new Uri(avatarUrl, UriKind.Absolute));
req.ContentType = "multipart/form-data;boundary=" + contentBoundaryBase;
req.AllowReadStreamBuffering = true;
req.Method = "POST";

req.UseDefaultCredentials = false;
req.Credentials = new NetworkCredential("uwstephens", "-");
File.WriteAllBytes(@"C:\Users\michael\Documents\test.txt", fileBytes);
req.BeginGetRequestStream(delegate(IAsyncResult result)
{
Stream reqStream = req.EndGetRequestStream(result);
reqStream.Write(fileBytes, 0, fileBytes.Length);
//reqStream.wr(fileBytes, 0, fileBytes.Length);
reqStream.Close();
req.BeginGetResponse(delegate(IAsyncResult result1)
{
WriteText("Image updated");
if (req.HaveResponse)
{
try
{
WebResponse resp = req.EndGetResponse(result1);
WriteText(resp.Headers["status"]);
}
catch (Exception e) { WriteText(e.Message); }
}
}, req);

}, null);
}

VideoCaptureDevice webcam = null;
CaptureSource captureSource = null;
private void loadCamera_Click(object sender, RoutedEventArgs e)
{
webcam = CaptureDeviceConfiguration.GetDefaultVideoCaptureDevice();

if (CaptureDeviceConfiguration.RequestDeviceAccess())
{
captureSource = new CaptureSource();
captureSource.VideoCaptureDevice = webcam;
captureSource.Start();
captureSource.AsyncCaptureImage(snap);
}
}

public void snap(WriteableBitmap b)
{

currentImage = GetImageStream(b).GetBuffer();
webcamImg.Source = b;
File.WriteAllBytes(@"C:\Users\michael\Documents\test\test.png", currentImage);
captureSource.AsyncCaptureImage(snap);

}


/// <summary>
///
Reads raster information from WriteableBitmap
/// </summary>
/// <param name="bitmap">
WriteableBitmap</param>
/// <returns>
Array of bytes</returns>
public static byte[][,] ReadRasterInformation(WriteableBitmap bitmap)
{
int width = bitmap.PixelWidth;
int height = bitmap.PixelHeight;
int bands = 3;
byte[][,] raster = new byte[bands][,];

for (int i = 0; i < bands; i++)
{
raster[i] = new byte[width, height];
}

for (int row = 0; row < height; row++)
{
for (int column = 0; column < width; column++)
{
int pixel = bitmap.Pixels[width * row + column];
raster[0][column, row] = (byte)(pixel >> 16);
raster[1][column, row] = (byte)(pixel >> 8);
raster[2][column, row] = (byte)pixel;
}
}

return raster;
}

/// <summary>
///
Encode raster information to MemoryStream
/// </summary>
/// <param name="raster">
Raster information (Array of bytes)</param>
/// <param name="colorSpace">
ColorSpace used</param>
/// <returns>
MemoryStream</returns>
public static MemoryStream EncodeRasterInformationToStream(byte[][,] raster, ColorSpace colorSpace)
{
ColorModel model = new ColorModel { colorspace = ColorSpace.RGB };
FluxJpeg.Core.Image img = new FluxJpeg.Core.Image(model, raster);

//Encode the Image as a JPEG
MemoryStream stream = new MemoryStream();
FluxJpeg.Core.Encoder.JpegEncoder encoder = new FluxJpeg.Core.Encoder.JpegEncoder(img, 100, stream);
encoder.Encode();

// Back to the start
stream.Seek(0, SeekOrigin.Begin);

return stream;
}

/// <summary>
///
Get image MemoryStream from WriteableBitmap
/// </summary>
/// <param name="bitmap">
WriteableBitmap</param>
/// <returns>
MemoryStream</returns>
public static MemoryStream GetImageStream(WriteableBitmap bitmap)
{
byte[][,] raster = ReadRasterInformation(bitmap);
return EncodeRasterInformationToStream(raster, ColorSpace.RGB);
}

dynamic com;

private void serialConnect_Click(object sender, RoutedEventArgs e)
{
com = System.Windows.Interop.ComAutomationFactory.CreateObject("ActiveXperts.ComPort");
dynamic count = com.GetDeviceCount();
StringBuilder sb = new StringBuilder();

com.Device = "COM1";
com.Open();
MessageBox.Show(com.GetErrorDescription(com.LastError));
string buffer = "";
System.Threading.Thread t = new Thread(new ThreadStart(delegate()
{

while (1 == 1)
{
com.Sleep(200);
buffer = com.ReadString();
if (buffer == "") { continue; }
serialOutput.Dispatcher.BeginInvoke(delegate()
{
serialOutput.Text += "\r\n" + buffer;
});
}
}));
t.Start();
}



void SendMessage()
{
if (com != null)
{
foreach (char c in input.Text)
{
com.WriteByte((byte)c);
}
input.Text = "";
}
}

private void input_KeyUp(object sender, KeyEventArgs e)
{
if (e.Key == Key.Enter)
{
SendMessage();
}
}

}

}

Silverlight talking to Arduino

This is an initial rough post, but I have managed to get Silverlight 4 beta talking to an ActiveXperts COM+ interface that talks to an Arduino over a serial connection.

Here is my first attempt to do a video of it. Looks like I’m going to need to learn how to make a screencast.

 

 

image

 

The C# code.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Shapes;
using System.Windows.Interop;
using System.Text;
using System.Threading;

namespace TestSerial
{
public partial class MainPage : UserControl
{
public MainPage()
{
InitializeComponent();
}

private void button1_Click(object sender, RoutedEventArgs e)
{
if (App.Current.InstallState == InstallState.NotInstalled)
{
App.Current.Install();
}
}
dynamic com;
private void button2_Click(object sender, RoutedEventArgs e)
{

com=ComAutomationFactory.CreateObject("ActiveXperts.ComPort");
dynamic count = com.GetDeviceCount();
StringBuilder sb = new StringBuilder();

List<dynamic> devices = new List<dynamic>();
for(int i=1;i<=9;i++)
{
devices.Add("COM" + i);
}

for (int i = 0; i < count; i++)
{
devices.Add(com.GetDevice(i));

}
devicelst.ItemsSource = devices;

}

private void button3_Click(object sender, RoutedEventArgs e)
{
//string device = devicelst.SelectedItem.ToString();
if (devicelst.SelectedItem == null) { MessageBox.Show("Please pick a port"); return; }
com.Device = devicelst.SelectedItem.ToString();
com.Open();
MessageBox.Show(com.GetErrorDescription(com.LastError));
string buffer = "";
System.Threading.Thread t = new Thread(new ThreadStart(delegate()
{

while (1 == 1)
{
com.Sleep(200);
buffer = com.ReadString();
if (buffer == "") { com.Close(); return; }
tb.Dispatcher.BeginInvoke(delegate()
{
tb.Text += "\r\n" + com.ReadString();
});
}
}));
t.Start();
}


}
}
 
The Xaml.
<UserControl x:Class="TestSerial.MainPage"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d"
d:DesignHeight="300" d:DesignWidth="400">

<
Grid x:Name="LayoutRoot" Background="White">
<
Grid.ColumnDefinitions>
<
ColumnDefinition></ColumnDefinition>
<
ColumnDefinition></ColumnDefinition>
<
ColumnDefinition></ColumnDefinition>
</
Grid.ColumnDefinitions>
<
Grid.RowDefinitions>
<
RowDefinition Height="Auto"></RowDefinition>
<
RowDefinition Height="Auto"></RowDefinition>
<
RowDefinition></RowDefinition>
</
Grid.RowDefinitions>
<
Button Content="Install" Height="23" HorizontalAlignment="Left" Name="button1" VerticalAlignment="Top" Width="75" Click="button1_Click" Grid.Row="0"/>
<
Button Content="Get Devices" Height="23" HorizontalAlignment="Left" Name="button2" VerticalAlignment="Top" Width="75" Grid.Row="1" Click="button2_Click"/>
<
ComboBox Name="devicelst" Grid.Row="1" Margin="1,0,0,0" Grid.Column="1"></ComboBox>
<
Button Content="Connect" Grid.Column="3" Grid.Row="1" Height="23" HorizontalAlignment="Left" Name="button3" VerticalAlignment="Top" Click="button3_Click"/>
<
TextBox Name="tb" Grid.ColumnSpan="3" Grid.Row="2" VerticalScrollBarVisibility="Visible"></TextBox>
</
Grid>
</
UserControl>



/*
  ASCII table
Prints out byte values in all possible formats: 
* as raw binary values
* as ASCII-encoded decimal, hex, octal, and binary values
For more on ASCII, see http://www.asciitable.com and http://en.wikipedia.org/wiki/ASCII
The circuit:  No external hardware needed.
created 2006
by Nicholas Zambetti
modified 18 Jan 2009
by Tom Igoe
<http://www.zambetti.com>
*/
void setup()
{
  Serial.begin(9600);

  // prints title with ending line break
  Serial.println("ASCII Table ~ Character Map");
}

// first visible ASCIIcharacter '!' is number 33:
int thisByte = 33;
// you can also write ASCII characters in single quotes.
// for example. '!' is the same as 33, so you could also use this:
//int thisByte = '!'; 

void loop()
{
  // prints value unaltered, i.e. the raw binary version of the
  // byte. The serial monitor interprets all bytes as
  // ASCII, so 33, the first number,  will show up as '!'
  Serial.print(thisByte, BYTE);   

  Serial.print(", dec: ");
  // prints value as string as an ASCII-encoded decimal (base 10).
  // Decimal is the  default format for Serial.print() and Serial.println(),
  // so no modifier is needed:
  Serial.print(thisByte);     
  // But you can declare the modifier for decimal if you want to.
  //this also works if you uncomment it:

  // Serial.print(thisByte, DEC); 

  Serial.print(", hex: ");
  // prints value as string in hexadecimal (base 16):
  Serial.print(thisByte, HEX);    

  Serial.print(", oct: ");
  // prints value as string in octal (base 8);
  Serial.print(thisByte, OCT);    

  Serial.print(", bin: ");
  // prints value as string in binary (base 2)
  // also prints ending line break:
  Serial.println(thisByte, BIN);  

  // if printed last visible character '~' or 126, stop:
  if(thisByte == 126) {     // you could also use if (thisByte == '~') {
    // This loop loops forever and does nothing
    while(true) {
      continue;
    }
  }
  // go on to the next character
  thisByte++; 
}

Entity framework Eager Loading error

If you you get this

"The execution of this query requires the APPLY operator, which is not supported in versions of SQL Server earlier than SQL Server 2005."

We ran into this because we generated it via a 2000 database and threw an error.

Load the edmx file in notepad.

<?xml version="1.0" encoding="utf-8"?>
<edmx:Edmx Version="1.0" xmlns:edmx="http://schemas.microsoft.com/ado/2007/06/edmx">
  <!-- EF Runtime content -->
  <edmx:Runtime>
    <!-- SSDL content -->
    <edmx:StorageModels>
      <Schema Namespace="TableModels.Store" Alias="Self" Provider="System.Data.SqlClient" ProviderManifestToken="2000" xmlns:store="http://schemas.microsoft.com/ado/2007/12/edm/EntityStoreSchemaGenerator" xmlns="http://schemas.microsoft.com/ado/2006/04/edm/ssdl">
       

Now all we need to do is change the 2000 to 2005!

Keep an eye on a reference.

When debugging I often find myself wishing I could just watch a single object throughout its life cycle. This is especially useful for debugging state problems (I’m thinking detached row error). Someone is modifying the state of your object and you need to figure out who. The problem lies in scoping. Every time you step in you have to change the watch window statement to track your objects state.

What you end up with is a nasty watch window.

The immediate window comes to the rescue!  Simply declare a variable with a globally unique name (DataRow watchMyRow=_dr;) for example. Then go to the watch window and add a watch for watchMyRow.  watchMyRow is always in scope. So now step through at your leisure and find the offending entry point and step deeper. Its that easy!

 

So we will start with a simple test program that calls methods with several different names and types.



using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleApplication2
{
class Program
{
static void Main(string[] args)
{
MyObject val = new MyObject();
Method1(val);
Method2(val);
Method3(val);
}

static void Method1(MyObject obj)
{
obj.state = 1;
}

static void Method2(MyObject myobj)
{
myobj.state = 2;
}

static void Method3(object obj)
{
((MyObject)obj).state = 3;
}
}

public class MyObject
{
public int state = 5;
}
}


We set our break points.



image



And at the end of the cycle our watch window looks like this! 



image 



All to track the same value on the same object!



 



The real problem is that with events thrown into the mix it becomes impossible to track state on some foreign object (Detached Row I loathe you!).



Now lets do the same example with the immediate window.



Our first break point gets hit. We type MyObject WATCHMYOBJECT=obj; into the immediate window.



image



Next I add that variable to the watch window.



image



Finnally after the many function calls this is the result.



image



 



I only had to watch one object the entire time! Now if I can only build a VSADDIN to automate this process (evil grin)!

Silverlight WCF Inner-Exceptions

Found a quick and dirty way to do WCF exceptions in silverlight http://code.msdn.microsoft.com/Project/Download/FileDownload.aspx?ProjectName=silverlightws&DownloadId=3473 .  The problem is that it doesn’t do inner-exceptions.

I changed the raw fault exception around a bit to get inner exceptions working.

 

    public static RawFaultException BuildRawFaultException(XmlDictionaryReader reader)
{
List<string> messages = new List<string>();
List<string> stacktraces = new List<string>();
while (reader.ReadToFollowing("Message"))
{
string message = reader.ReadElementContentAsString();
string stackTrace = reader.ReadElementContentAsString("StackTrace", reader.NamespaceURI);
messages.Add(message);
stacktraces.Add(stackTrace);
}
RawFaultException e = null;
for (int i = 0; i < messages.Count; i++)
{
if (e == null) { e = new RawFaultException(messages[i]) { stackTrace = stacktraces[i] }; }
else { e = new RawFaultException(messages[i], e) { stackTrace = stacktraces[i] }; }
}

return e;

}
}

Flag enums

I was working on a project that needed to use flag enums to store state.  Flag enums are great, except after 2^15 the numbers get hard to calculate. I resorted to using excel to generate the enum code for me, that is until I learned I can do math expressions inside of enums! What I forgot is that 2^0 is not equivalent to Math.Pow(2,0).  This is when I discovered my old friend shift.

 

 

using System;

namespace TestEnum
{
class Program
{
static void Main(string[] args)
{
Console.WriteLine(oldway.All);
Console.WriteLine(newway.All);
}
}

[Flags]
enum oldway
{
None=0,
One=1,
Two=2,
Three=4,
Four=8,
All=15
}

[Flags]
enum newway
{
None = 0,
One = 1<<0,
Two = 1<<1,
Three = 1<<2,
Four = 1<<3,
All = (1<<4) - 1
}
}

 


As you can see they both work the same :)


image

State Bag for all objects

Extension methods are very powerful, but sometimes you need to store state on the object you are processing in an extension method.  The problem is implementing state maintenance in a static method can be a real chore.  Not to mention when you only want to track state on an object you can’t.  I wrote this quick and dirty state maintenance set of extension methods.  There is a caveat that I cannot fix at the time of writing. 

 

If you store data in the statebag, you need someway of knowing when the object is getting destroyed so that you can manually call ClearVariables.  If you do not clear the variables the values will be left in the statebag FOREVER causing massive memory leaks!  I would like a way to alleviate this if anyone has any ideas.

 

using System;
using System.Collections.Generic;

namespace StateBagTest
{
class Program
{
static void Main(string[] args)
{
object o = new object();
o.Set("newvar", 5);
int number = (int)o.Get("newvar");
o.ClearVariables(); //very very important!
Console.ReadLine();
}

}

public static class StateBag
{
static Dictionary<int, Dictionary<string, object>> _stateBag = new Dictionary<int, Dictionary<string, object>>();
public static void Set(this object obj, string var, object value)
{
int hashcode = obj.GetHashCode();
if (!_stateBag.ContainsKey(hashcode))
{
_stateBag.Add(hashcode, new Dictionary<string, object>());
}
_stateBag[hashcode][var] = value;
}

public static object Get(this object obj, string var)
{
int hashcode = obj.GetHashCode();
if (_stateBag.ContainsKey(hashcode) && _stateBag[hashcode].ContainsKey(var))
{
return _stateBag[hashcode][var];
}
return null;
}

//Really need to call this when your object is done using the state bag, which may be hard for some objects you are extending!
public static void ClearVariables(this object obj)
{
int hashcode = obj.GetHashCode();
if (_stateBag.ContainsKey(hashcode))
{
_stateBag[hashcode] = null;
}
}
}
}