[BRLTTY] Braille Display Bluetooth communication

[Piotr Kleinschmidt]

Hello,


I'm looking for information about communication details between Braille 
Display and host device via Bluetooth connection. I have some doubts and 
questions related to subject issue:

1. Some Braille Displays support Bluetooth Classic (up to 3.1) and some 
support Bluetooth Low Energy (4.0 and higher). If I try to pair and then 
connect to them, should I use a specific Bluetooth profile? First, I 
thought connection can be established via Serial Port Profile, but as 
BLE doesn't directly support it, I am uncertainty about that.

2. Does every Braille Display's manufacturer implement his own Bluetooth 
communication protocol or is there any imposed standard that must be 
met? There is a lack of information about that. My main source is brltty 
code, which suggests that every manufacturer has his own protocol. 
However, are there any common parts between them at least? For example 
data frame length,  end of data sign etc.


Thank you in advance for your replies. As there is a little information 
and official documentation for Braille Devices, I hope you can dispel my 
doubts.


Best regards,

Piotr