Android Question Receiving Bytes of data between 0 and 255

[Danki_87]

Hi everyone!

I'm having some problems receiving bytes of data over bluetooth.
The project I'm trying to make is a bluetooth oscilloscope. I have a microcontroller that samples the signal, and then it sends it as a single byte to my android device using a TTL to bluetooth adapter. Then I want to display the signal on the screen.

I'm sucked now in the communications. The android device receives the data as a character, then I tried to use the ByteConverter library to interpret the character:

Dim bc As ByteConverter
Dim Data(1) As Char
Dim Number(1) As Byte

Data(0) = TextReader1.ReadLine
Number = bc.CharsToBytes(Data)

When I receive a number between 0 and 127, this code works just fine. However, when I receive a larger number it just returns -3.

I'd appreciate any help in other ways to change from chars to bytes.

 

[NJDude]

That is correct because of the BYTE limits, see more HERE, even more info HERE

 

[Erel]

B4A (and Java) use signed bytes. The data you receive is correct. 253 is converted to -3 (256 - n).

 

[Danki_87]

Thanks, It's good to know I'm on the right way. I supose I can sacrifice a little bit of resolution and work with data from 0 to 127.

However, Is there any other way to obtain the numerical information of a character sent oover the serial port? (other than using the byte converter library)

 

[Beja]

Maybe I am not following.. but as far as I understand from what you wrote I was expecting to define the data array as string, not char.. or even just use one string variable to hold the incoming data. this way you end up with a string-represented byte, 7F for example.. then convert this value to a true Hex byte.

 

[Erel]

You don't need to do any conversion to the actual data as it is correct. If you want to see the unsigned value then you can use the sub I posted here: https://www.b4x.com/android/forum/threads/unsigned-variable-types.30911/#post-179784