Android Question binary data with bluetooth

[kenad]

Hi Erel
Your serial example works well.
I want to send and receive binary data , not text
Instead of using textwriter , and textreader to read the serial buffers

TextReader1.Initialize(Serial1.InputStream)
TextWriter1.Initialize(Serial1.OutputStream)


How do you get the data into a byte array?
I need to be able to send bytes with values from 0-0xff and the textreader/writer gets in the way

The system will be getting 34 bytes every 500 msec

Is there a length command or some way of telling how many bytes the buffer has in it?
In VB6 I would do something like this


Dim datain as variant
Dim dataout(31) as byte

If MSComm1.InBufferCount >=34 then
Datain = MSComm1.Input

I then process the data put it in the dataout buffer and return it to blue tooth

MSComm1.output = dataout


What would be a similar way in B4A?

Thanks for your help
Ken

 

[Erel]

You shouldn't use TextWriter / TextReader with Bluetooth connections.

In Android you are not allowed to block the main thread. You should instead use AsyncStreams.
Android Bluetooth / BluetoothAdmin Tutorial
[URL='https://www.b4x.com/android/forum/threads/7669/#content']AsyncStreams Tutorial [/URL]

It is simple to send and receive bytes with AsyncStreams.

 

[kenad]

Ok Thanks
I did try AsyncStreams but the program stopped as soon as I tried to connect to a bluetooth connection.
I will probably investigate the program again.

as my project totally revolves around the blue tooth , I did the following with the serial example, and if works for my requirements.

'Activity module
Sub Process_Globals
Dim Serial1 As Serial
Dim tmpin As InputStream
Dim tmpout As OutputStream
Dim bufin(1023),bufout(1023) AsByte

End Sub

Sub Serial1_Connected (Success AsBoolean)

If Success Then
tmpin=Serial1.InputStream 'connect streams to input and output streams in program
tmpout=Serial1.OutputStream
connected = True

' this section writes bytes to bluetooth
tmpout.WriteBytes(bufout,0,7)

this section reads from bluetooth but waits using doevents

'main loop
DoWhileconnected = True

'first wait for serial data

DoWhile bytenum = 0
bytenum= tmpin.BytesAvailable
DoEvents
Loop

Timer1.Enabled=True 'wait 20 ms , and read buffer
DoWhileTimer1.Enabled=True
DoEvents
Loop
'then read serial info
byteread=tmpin.ReadBytes(bufin,0,bufin.length)

 

[Erel]

Please use [code]code here...[/code] tags when posting code.

You shouldn't use such code. It will not be reliable.

You should use AsyncStreams and never try to block the main thread with such loops. It will not work.

 

[kenad]

Is there a sample program that works on android 4.4.2
I tried the bluetooth sample , but it crashes about 1 sec after searching for devices, there is only one device available.
does it require more than one?
I tried the compiled program on 2 different tablets to see if it made a difference, but they both reacted the same way.
the serialexample sample file compiles and works on both test tablets , so I know the b4a is compiling properly, and that the test units connect properly.

 

[kenad]

this is a log from the bluetooth program , I don't know enough about Java to know why this program fails, perhaps you could let me know what is wrong?
I haven't made any changes to the sample file.
Thanks for your time
Ken

 

[Erel]

The Bluetooth example based on AsyncStreams should work on all Android devices running Android 2.0+.

For the example to work you need to run it on two devices and connect them.