Android Bluetooth / BluetoothAdmin Tutorial

[Erel]

This tutorial is an improved version of the previous Serial tutorial.
We will create a chat example between two Android devices.

Using BluetoothAdmin we search for in-range devices and then allow the user to connect to a device. If the device were not paired before then a dialog will show to confirm the pairing process.

The first activity includes two buttons:



"Search for devices" button will start a discovery process that takes about 12 seconds.

"Make device discoverable" button does two things. First it sends an Intent that makes the device discoverable for 300 seconds. It then calls Serial1.Listen to listen for incoming connections.

If the connection is established successfully then we start the second activity:



In the second activity we use AsyncStreams to send and receive messages.
As we use AsyncStreams in both sides of the connection we can easily use "prefix mode". In this mode we always receive complete messages.

The code is attached.

[raphaelcno]

That looks very nice.
Is it possible to show "txtLog" with two different colours, for instance received text in red colour and sent text in blue colour?
Is it also possible to show a time stamp ("12:34:56.789" or similar) before the text "You" and "Me"?

[Erel]

It is better to start a new thread for these questions. You can use the RichString library to change the colors. Adding the time stamp should be pretty simple. You should add it in Sub LogMessage.

[walterf25]

Hi Erel, i tried your example for bluetooth communication, and i must say is very good, however i'm using a RN-42 bluetooth i bought from sparkfun electronics, i'm able to connect to it via my HTC Evo shift i wrote a small program in visual studio to receive and send the text strings, i can receive the strings ok sent from my phone to my program written in visual studio, but when i send a string back to the bluetooth module, your program shuts down giving me a foreclosed error, i have tried this before with app inventor and it should work ok, the module is connected to my computer through a serial port, i need help figuring out where this is going wrong! can you maybe give me some tips.

Thanks,
Walter

[Jonas]

I guess you dont send the prefix characters from you VS program which is needed when using prefix mode. Try not using prefix mode and you will see everyting will work!

/J

[walterf25]

Originally Posted by Jonas

I guess you dont send the prefix characters from you VS program which is needed when using prefix mode. Try not using prefix mode and you will see everyting will work!

/J

Hi Jonas, thanks for your reponse, i'm not sure what you mean when you say prefix mode, can you elaborate a little more?



thanks,
Walter

[Jonas]

When you initialize the Asyncstream in this exemple the following code is

AStream.InitializePrefix(Main.serial1.InputStream, True, Main.serial1.OutputStream, "AStream")

But if you instead use

AStreams.Initialize(Main.Serial1.InputStream, Main.Serial1.OutputStream, "AStreams")

The program wont be halted beacuse it cant find the prefix in the incoming data stream.

When the AStreams_NewData event triggers it might just hold a few bytes of the whole message you want to receive so you have to append the Buffer data into a variable and manipulate the data later.
Or just update txtLog.Text = txtLog.Text & the buffer data

/J

[walterf25]

Originally Posted by Jonas

I guess you dont send the prefix characters from you VS program which is needed when using prefix mode. Try not using prefix mode and you will see everyting will work!

/J

thanks Jonas that worked like a charm, thanks much buddy!

cheers,
Walter

[raphaelcno]

Originally Posted by raphaelcno

Is it possible to show "txtLog" with two different colours, for instance received text in red colour and sent text in blue colour?
Is it also possible to show a time stamp ("12:34:56.789" or similar) before the text "You" and "Me"?

The solution for text color and time stamp is shown in this thread:
http://www.basic4ppc.com/forum/basic...ichstring.html

[pinoy_ako]

i tried compiling the provided sample with b4a 1.6 and am having error.
is this sample not compatible with 1.6? or im just missing something?

thanks