[BRLTTY] BrlTty, NVDA, & BrailleNote Touch

[Jackie McBride]

Hey, Dave, thanks! I did know that bt can, in cases where the hardware
dictates it, , emulate a com port. You've inspired me to do a little
reading on rfcom. I disabled her bluetooth speakers to see if that
would help, which, of course, it didn't, & then reenabled them, & now
they're sounding distorted. So I guess I now have some bluetooth audio
problems to straighten out also, but that's well beyond the scope of
this list, I feel positive. My hair's always short & turning grey cuz
I'm constantly pulling it out doing computer work.

On 5/18/18, Dave Mielke <dave at mielke.cc> wrote:
> [quoted lines by Jackie McBride on 2018/05/18 at 15:03 -0700]
>
>>So might I ask--what does that really do, as it appears the device had
>>actually been discovered. Or am I misinterpreting the log?
>
> No, you aren't missing anything in the log. You just lack a bit of knowledge
>
> about how Bluetooth works. I'd say that'd be a rather common weakness that
> most
> people suffer from. :-)
>
> The BrailleNote Touch, just like lots of other braille devices, implements
> Bluetooth communication by emulating a serial port. Emulating a serial port
>
> over Bluetooth uses a protocol called RFCOMM, which, for the purposes of
> simplistic explanation, is kind of analogous to the TCP/IP protocol on a
> network. It supports several services (which Bluetooth calls profiles)
> running
> simultaneously, with each one using a different RFCOMM channel. Again, for
> the
> purposes of a simplistic explanation, you can think of RFCOMM channels as
> being
> kind of like TCP/IP ports.
>
> So, yes, the device was detected. The problem was determining which RFCOMM
> channel to use. Some braille devices (mostly the older ones) always use the
>
> same channel, so brltty drivers have the capability to define which channel
> to
> use. Other braile devices (most of the newer ones) use a channel that's
> dynamically assigned when their Bluetooth interface is started. For those,
> it's
> necessary for the host to ask the device which channel to use for its Serial
>
> Port Profile. this is done via Bluetooth's Service Discovery Profile, so
> brltty
> drivers also have the capability to request that service discovery be
> performed.
>
> The bug was that the HumanWare braille driver wasn't requesting that service
>
> discovery be performed. This has been fixed within the development code. The
>
> discovery=yes device parameter is the way to manually request service
> discovery.
>
>>BTW. I'm just curious, you understand.
>
> Of course! Curiosity like yours is encouraged on this list.
>
> --
> I believe the Bible to be the very Word of God: http://Mielke.cc/bible/
> Dave Mielke            | 2213 Fox Crescent | WebHome: http://Mielke.cc/
> EMail: Dave at Mielke.cc  | Ottawa, Ontario   | Twitter: @Dave_Mielke
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Remember! Friends Help Friends Be Cybersafe
Jackie McBride
Helping Cybercrime Victims 1 Person at a Time
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