[BRLTTY] brailliant bi display support

[Mario Lang]

kendell clark <coffeekingms at gmail.com> writes:

> I know brltty supports the brailliant displays, but does it support the newest one,
> called the brailliant bi?

Yes, the BI 40 and B 80 are supported.

> They say when they plug it in nothing happens and I'm wondering if
> maybe it's a bluetooth display.

The Brailliant B(I) models can work either via USB or Bluetooth.
The user should be able to change this in the inernal menu.

> Brltty is using it's stock config file, which autodetects the display,
> but does brltty autodetect bluetooth displays?

Currently, only if the bluetooth address of the display has been
specified (in brltty.conf, or via -d bluetooth:...) and has already been
paired (via bluetoothctl or some other means).
See Documents/README.Bluetooth for a detailed descriptions on how to pair
with bluez4 and bluez5 from the command-line.

> If not, would it be possible to add this?  Obviously you'd have to
> pair with the display brltty can't read your mind.

I actually have a plan to implement auto-pairing for some kind of
displays.  The end goal would be to specify the PIN as part of the
device specifier, so that BRLTTY can pair the device if need be.
However, I haven't really come to tackling this yet, likely when the
weather turns less humid and more autumny again.  Basically, the idea is
to use the bluez5 D-Bus API to re-implement what bluetoothctl does
manually now directly in BRLTTY.  And, newer devices implement a different
pairing protocol, which no longer requires a PIN code, but only requires
to acknowledge a token received by the remote device.  While it is
slightly fishy from a security point of view, this new pairing method
could be fully automated if we just ack the token whenever we see it.
Combined with our growing database of bluetooth names, we should be able
to more or less fully auto-connect to a bluetooth display.  The only
hurdle that remains is that the user will still need to put the device
into pairable mode at least once.  If anyone wants to beat me to writing
this, I am happy to share my findings so far regarding the D-Bus API of
bluez.

-- 
CYa,
  ⡍⠁⠗⠊⠕