[BRLTTY] Bluetooth connection problem

[Mario Lang]

lars at lamasti.net (Lars Bjørndal) writes:

> On one of my rpis, I have recurring connection problems. The connection can
> work for hours or even days, but suddenly, the connection stops working.
> Typically, the reconnection after a braille display sleep won't work. A
> system reboot doesn't solve the problem.
>
> In bluetoothctl, I get the following from info <addr>:
>
> (Please note the Name field. Shouldn't that have been Handy Tech Active
> Braille ...
>
> Device 00:07:80:41:1E:B7
>         Name: WT12-A
>         Alias: WT12-A
>         Paired: yes
>         Trusted: yes
>         Blocked: no
>         Connected: no
>         LegacyPairing: no
>         UUID: Serial Port       (00001101-0000-1000-8000-00805f9b34fb)
>         UUID: Human Interface Device... (00001124-0000-1000-8000-00805f9b34fb)
>         UUID: PnP Information    (00001200-0000-1000-8000-00805f9b34fb)
>         Modalias: bluetooth:v0047pF000d0410

That looks like a hardware bug.  If you haven't accidentally checked the
wrong Bluetooth address, the device name should indeed be something
else.  Do you specify the bluetooth address in your brltty
configuration, or do you rely on the ability of BRLTTY 5.5 to find the
device on its own?  If so, that will fail, since BRLTTY doesn't know
anything about the "WT12-A" bluetooth friendly name.  You could try to
go back to specifying the bluetooth address directly, maybe BRLTTY is
still able to connect to the wrongly named device.

> Doing connect 00:07:80:41:1E:B7
>                 Attempting to connect to 00:07:80:41:1E:B7
>                 Failed to connect: org.bluez.Error.Failed
>
> To fix the problem, I have to remove the device, and then re-pair it.

After re-discovery, is the device name correct, or does it still show up
as WT12-A?

I sometimes have a similar problem with the Active Star, however, when
that happens, I usually am missing the Human Interface Device UUID and
therefore have no working keyboard input.  Re-discovering seems to be
the only thing that helps in that situation.

> Any ideas in how to fix this problem?

Contact Handy Tech.  This does not look like a software problem on the
host.  It looks like a confused bluetooth stack on the side of the
Braille display.  WT12-A seems to be the original name of the hardware
they are using in the Active Braille.  At least that is what a quick
google search suggests.  The host should never see the un-rebranded
bluetooth name, if it does, it looks like a bug on the side of the
display.  Felix, what do you think?

-- 
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