Arduino Bluetooth - send but not receive

[headingwest]

Hi All,

I have an Arduino with the HC-05 bluetooth.

Adapting the example code for the bluetooth library I can send text to the Arduino, but I get rubbish back. In fact the return text has different number of bytes depending on the character.

The core Arduino code returns the same byte it receives:

while (Serial1.available() > 0) {
      inByte = Serial1.read();    // Get the received Byte works fine
      Serial.write(inByte);       // Write Byte to serial monitor
      bFoundData = true;
      Serial1.write(inByte);      // Return Byte value to bluetooth as reply
    }

And I would think that the B4A would accept it back:

Sub AStream_NewData (Buffer() As Byte)
   
   sByteIn = BytesToString(Buffer, 0, Buffer.Length, "UTF8")
   sb.Append(sByteIn)
   
   If sByteIn.EndsWith(CRLF) Then
      LogMessage("You:", sb.ToString)
      sb.Remove(0, sb.Length)
   End If
   
End Sub

So if I send "h" I want "h" back. But the return byte is -5

Here are some sample send and return values

h -5
i 86
j -106 and then -5 (2 bytes are returned)
k -5
l 22 and then -5 (2 bytes are returned)

Any ideas??

 

[agraham]

Bytes are regarded as signed in Java so get sign extended when cast to a wider type like Int. If you want a positive value you can mask the result with Bit.And. Try

 SomeVar = Bit.ParseInt(Bit.And(SomeByte, 0xff), 16)

You might need to mask the parity bit as well.

Also sb.Append(sByteIn) appends the value of the byte not the character it represents. Try sb.Append(Chr(sByteIn))

 

[headingwest]

Thanks AGraham, partially solved. There's something else happening in the AsyncStreams, here is a test event:

Sub AStream_NewData (Buffer() As Byte)
   Dim holdVar As Byte 
   Dim lenbyte As Int
   lenbyte = Buffer.Length 
   holdVar = Buffer(0)   
End Sub

This event only fires on certain byte values returned:
a - 97
b - 98
c - event fails to fire
d - 100
e - event fails to fire
f - event fails to fire
g - 103
h - 104

etc. This is replicable so "c" never triggers the NewData event while "a" always triggers the event.

 

[headingwest]

I just tried the most basic send from the Arduino:

Serial1.write(103);

103 triggers the NewData event in b4A
102 does not trigger the NewData event in B4A

 

[Erel]

AsyncStreams doesn't check the actual data. It just raises an event with the data. The problem is somewhere else.

 

[agraham]

You can get more than one character per event. Check the length of Buffer().