Totally Weird. There is a Close projection for C++ and JavaScript, and even .Net but not C# for WinRT.
http://msdn.microsoft.com/en-us/library/windows/apps/windows.networking.sockets.streamsocket.close.aspx?cs-save-lang=1&cs-lang=javascript#code-snippet-1
I am successfully connecting using the very cool PeerFinder api. When I want to force the connection to close, I dispose of the socket (as Close is not an option in C#). This appears to work, but occasionally, subsequent connections connect to bluetooth, rather than WiFi. Bluetooth is substantially slower than WiFi, so the experience is poor.
If I have Bluetooth turned off, then all works great, but I can't ask our customer to do that.
What is the correct way to Close a StreamSocket connection in C#?
The docs you link say
"For apps written using the .NET Framework 4.5 in C# and VB.NET, the
Close method is exposed as the Dispose() method on the StreamSocket."
The best way to use this method is via a using block
using(var stream = new StreamSocket())
{
}
The Dispose method will be called at the end of the block.
Related
This is a basic question of understanding. I'm trying to follow this explanation http://www.barryvandam.com/node-js-communicating-with-arduino/ but something there sounds a bit off to me.
As far as I understood before, I only need to push the standard Firmata code into the Arduino and code via Node.js to call actions and information from the Arduino.
But in this link they point our that I need to upload a code to the Arduino, which will obviously delete the Firmata code that is now there. wouldn't it result in loosing connection to the Arduino?
How does it work?
many thanks!
The example above does not use Firmata, though Firmata makes things easier. If you want to implement your own serial control protocol, there nothing stopping you.
However, if you load StandardFirmata on your Arduino, and then use the Firmata.js package in node, then you have a full-featured, well established serial protocol and an api to access the pins from.
There are Firmata controller implementations for most languages out there.
On top of Firmata.js, you might choose to use an abstraction called Johnny-Five. Johnny-Five abstracts the pins as components, with an intuitive API. Instead of controlling a servo by setting a pin value, you create a servo, and call servo.to(angle). It is kind of like jQuery but for hardware. It abstracts the platforms and devices in such a way that the shape of the interface is the same, but the hardware might be completely different. It is a very comfortable place to develop from.
Firmata is a set of functions that you can pre-load onto your Arduino that libraries like Johnny-Five can call to perform certain tasks.
As previously said by the author of the accepted answer, you don't have to use it, you can write your own logic to send and receive custom message.
In Node.js you can use the node-serialport library to send the message:
myPort.write();
Then read the message from the Arduino with the built in Serial library:
while(radio.available()){
radio.read(chr, 1);
}
Firmata is one way to communicate with an Arduino, you do not have to use it.
You can "talk" to Arduindo directly using the SerialPort module - which is what the linked example is doing.
I am experimenting with Bluetooth Low-Energy (BLE) for the purpose of connecting a hardware device to an Android application. My goal is to send a recognizable piece of data to an Android phone.
I am using the keyfob from Texas Instrument's CC2541 Mini-development kit, and am programming it using the IAR Workbench (which I am learning on the fly). My issue is that I cannot figure out what code should be used to send data from the keyfob to the phone.
I understand that this is somewhat vague, but because of the non-disclosure policies of my company I cannot share the code that I am working with. Does anyone have any references to code for the IAR Workbench that will allow the CC2541 to send a piece of data? Right now, I prefer to use GATT if that helps.
Thanks, and please ask me more questions if I need to clarify anything.
Assuming you're working from a pre-existing service profile, there is a function for every service called ServiceName_SetParameter(). Calling that function will change the characteristic value. When the characteristic is read by the phone, it will receive this value. If the characteristic supports notifications, and your phone has registered for notifications on that characteristic, the new value will be transmitted whenever SetParameter is called.
You can implement any proprietary protcol to connect to and interact with your beacon device. It can assume other roles than just the beacon task. It can also listen to and respond to connection attempts thus expanding into a lot more than a regular beacon.
If you study the cc2541 close you realize it is a pretty advanced IO controller that offers a lot of IO signal possibilities. That way you could use the cc2541 as the heart of an IO control application where you measure and control equipment. Mobile apps can then easily connect to your beacon/IO Controller device and interact with the machinery it is hooked up to. As you see, it´s a remarkably versatile system on chip and a cool circuit to learn to program.
I have a little problem. I have developed a midlet application that call some webservices through internet. I'm using cell phones with GPRS connection. For some time it runs as I wanted, run the apps, call the webservices through the GPRS, it returns the result, call the webservices again, and so on.
But say, I call the webservices and after the apps return the result I needed, I left it for a while. The next time I continue to access the webservices, the apps takes a while to connect through the GPRS. In nokia, it is marked with a G in a box. In SE it is marked with a glowing globe. This 'G' in the box or the glowing globe will appear after a while or won't appear at all, but the apps is still trying to connect to the internet.
Does it come from my apps or it come from the cell phone? And could I know [or the apps knows] that at the moment the apps tries to connect the GPRS is ready?
Thanks a lot for your responses...
There is nothing in Java ME (i.e. J2ME) that can control whether or not the device is connected, unfortunately. All you can do is try to connect.
Make sure you are properly closing all your connections, though. Including the HttpConnection object, not just the input/output streams.
I need just a basic example or tutorial of making a mobile phone and a computer communicate via Bluetooth.
A good link/website to start from is also appreciated.
Server part (computer part) can be made on many programming languages (Java, C++, Python or even something else).
Client part (mobile phone) must be a Java Micro Edition MIDlet.
After many days of research, I managed to make an application that sends (in real time) screenshots of area around the mouse cursor on a computer to a mobile phone client.
Both client and server are written in Java.
I used BlueCove to make the desktop part. It is a JSR-82 implementation (the same protocol as in MIDP), so desktop and mobile parts share a lot of code.
In case someone needs it, I release the application as public domain, without any responsibilities.
Download the code
I'm not really proud of it. After all, I was 15 when I wrote it. The code is horrible in some places, but I enjoyed making the abstraction for code reuse.
I need to connect to a Bluetooth device through virtual COM port created in Windows. It's easy when the port has been already created during manual pairing procedure. But I would like my application to relieve an user from the manual pairing of a device. I would like to present all devices in the range, allow user to chose one, and then create virtual COM port connected with the selected device. I'm not trying to avoid the pairing procedure itself, but rather I would like to invoke it by my application.
I started getting familiar with Microsoft Bluetooth API. And then some doubts arose. I've been wondering what happen if some user would use different (than Microsoft's) Bluetooth stack? Is the Microsoft's API the real Bluetooth API, which have to be implemented by any other Bluetooth stack provider? Or rather each provider has its own API, and the Microsoft's is only one of many other?
Thanks everyone for valuable input. I'd like to summarize what I've found so far. The Microsoft Bluetooth API is not operating system API. Application written against it will not cooperate correctly with any other Bluetooth stack. It seems that applications which are intended to cooperate with multiple stacks need to provide some stack abstraction layer, and stack specific code for all of them.The other solution is to allow user for manual pairing of the Bluetooth device, which eventually create some virtual device in the operating system (e.g., COM port). Then the application can use standard interface of such a device.
I can't speak for the Microsoft Bluetooth API, but there are multiple Bluetooth stacks available for the PC platform (even more for mobile devices).
The underlying API is defined by the Bluetooth Core Spec and so all stacks should be able to interact, in fact it is mandatory that they interop or they cannot use the Bluetooth name and logo.
As to pairing, your going to have a hard time getting devices to pair if they have default security, which requires a pin code.
Things might be simpler in the (near) future, as the Bluetooth standard has introduced a new security model, secure simple pairing, which has a 'just works' mode that requires no Pin code. This is still stronger then the current security, except against Man in the middle attacks. However, it could be a while before you see the chips with this feature in PCs.
If you can change to using .NET :-/ I can recommend our library 32feet.NET.
For explicit pairing there's BluetoothSecurity.PairDevice. We can also create the virtual port for you, for example:
BluetoothClient cli = new BluetoothClient();
BluetoothDeviceInfo[] list = cli.DiscoverDevices();
BluetoothDeviceInfo selected = GetUserToSelectOne(list);
BluetoothSecurity.PairDevice(selected, pin);
// Ask Win32 to create a virtual serial port
selected.SetServiceState(BluetoothService.SerialPort);
However I really don't like virtual serial ports so I always suggest that people use a normal sockets connection using our BluetoothClient class, it will automatically handle a pairing request if required.
On Win32 we support the stacks from Microsoft, Widcomm/Broadcom, and BlueSoleil. On Widcomm there's no support for SetServiceState there yet, and their API has no support for responding to pairing requests. BlueSoleil should support both.
A brief user's guide is at 32feet.NET — User’s Guide, and all the class documentation is available at the main site http://32feet.net, the Widcomm documentation is only in our code repository at the moment.