Bytes greater than 127

[hamidnaghi]

Once I send the bytes with value of 128 to 255 by Bluetooth to Android then I see different bytes. I receive -17, -65, -67 instead of 128 to 255. But, it works with 0 to 127. Something happens to "(byte[]) msg.obj" with negative values in the
private final Handler mHandler = new Handler()
in the section
case MESSAGE_READ:
byte[] bufferRead = (byte[]) msg.obj;

Would you please resolve it?
Best regards
Hamid Naghizadeh

[MacroYau]

This is due to the fact that primitives in Java, including byte, are signed. You can implement int unsignedByte = signedByte & 0xFF as instructed in the Stack Overflow answer as a workaround.

[hamidnaghi]

Thank you Macro,
But, If I send any negative value then it only receive -17, -65, -67.

[hamidnaghi]

Even, If I implement int unsignedByte like your comment then I will receive 3 bytes 239, 191, 189 instead of 1 byte for each negative value I send out. And it is same as negative one, just in unsigned value.

[MacroYau]

Can you specify your expected input and output?

[hamidnaghi]

I'm sending 0 to 255 from another bluetooth to android and I'm expecting to receive same number on Android, but I'm receiving 0 to 127 for numbers 0 to 127 I send which is match and OK, but for other numbers between 127 to 255 I'm receiving only 63, not same number that I sent.

[hamidnaghi]

The input from other bluetooth is an array with 256 elements contains 0 to
255 that I'm sending to Android, But, the output on Android is 0 to 127 and
only 63 for the data input between 128 to 255.

On Thu, Jul 7, 2016 at 8:15 AM, Macro Yau [email protected] wrote:

Can you specify your expected input and output?

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[MacroYau]

@hamidnaghi Now I understand your issue after testing with an Arduino Bluetooth module. It is caused by the handling of the received bytes in the SPPService class, which incoming bytes are buffered into a String (and hence distorted the bytes since some of them cannot be properly encoded).

A simple workaround would be encoding the values as Strings on the device sending the data, if possible. Alternatively, you can consider modifying the SPPService class to enable it to appropriately handle the incoming bytes.