Today's project isn't "really" a hardware project, but it does involve Bluetooth and controlling your PC, so I guess it's close enough... :)
What does this mean? Well how about enabling...
If you’ve ever used applications like the Office Remote that seem to take over your computer you’ll know that it can provide quite the “magic” experience. As with all magic technologies this one is quite simple as well. All we need is a computer with Bluetooth that runs a small app with a Bluetooth listener and a Windows Phone app that connects to that listener app via Bluetooth. For this demo app I’m going to make the Windows Phone app act like the Start button on a Windows machine.
Simulating the Windows key
The listener application is a small WPF app that has only one button. That button will act like the Start button. To interact with the operating system and simulate a keyboard press we’ll need to import user32.dll and hook into its keybd_event. We’ll want to send ctrl + esc to Windows (acts the same as the Windows key)
Building the Bluetooth listener
Adding Bluetooth support to a .NET application isn’t the easiest thing to do. Luckily for us there are libraries out there that take out the hassle. For this project I used Peter Foot’s 32feet.NET library available through NuGet
A small note on this package as found on the 32feet.NET product page
“Bluetooth support requires a device with the Microsoft or Widcomm Bluetooth stack”
Luckily for me, my device uses the Microsoft BT stack, so I’m good to go. Now on to the code, we’ll need to start a BT listener and once connected read data from a networkstream. If we receive a certain message we’ll execute the ShowStartMenu() method.
This is the code for the loop that runs in the second thread. First we declare a buffer of 1KB, more than enough for this sample. Next we start an infinite loop, in that loop we declare a BluetoothClient and a Stream. Once a client connects through the AcceptBluetoothClient method we fetch a stream and set the connected flag to true. As long as we’re connected we read data from the stream into the buffer, once we receive actual data we’ll decode it from a byte array (the buffer) into a string (the original message). In this sample the message will be 5 bytes but the buffer can hold 1024 bytes. It will fill up the remaining bytes with “\0” so we’ll need to chop that of with a Substring. If the received string is “Start” we’ll flip to the Start screen. If we read from the stream but the number of received bytes is zero, we’ve lost the connection to the client.
Fire up the WPF app, make sure the button flips you to the Start screen and let’s get started on the WP8 app!
Windows Phone Client
The Windows Phone app consists of two pages. The MainPage is for selecting a Bluetooth peer to connect to and the ConnectedPage has the same button as the WPF application. The app uses MVVM Light, everything happens in the MainViewModel. Both the MainPage and ConnectedPage use MainViewModel as their datacontext. For navigation I’ve added the always helpful Cimbalino NuGet package and registered their NavigationService in SimpleIoc through the ViewModelLocator
And that’s it! The message gets written into the DataWriter, stored in the stream and the stream gets flushed. In the WPF app the string gets read into the buffer as a byte array, gets converted back into a string and the Start screen appears!
In this post I’ve discussed how to connect your Windows Phone device to another bluetooth enabled device and use a service running there.
While maybe it's not a complete Office Remote example, it should be more than enough to get you started!
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