[BRLTTY] Bluetooth connection problem

[Lars Bjørndal]

Hi, Mario!

Nother note:

On the system where I have connection problems, I sometimes experience
that a key press on the braille display doesn't do anything. The
display, however, moves when the cursor is moved.

Some lines from the log says:

aug. 11 05:06:56 kul3 brltty[1032]: input byte missing at offset 0
aug. 11 05:06:56 kul3 brltty[1032]: Partial Packet: 79
aug. 11 05:07:21 kul3 brltty[1032]: autoreleasing key: ? (Grp:0 Num:2)
aug. 11 05:07:21 kul3 brltty[1032]: autoreleasing key: B3 (Grp:0 Num:11)
aug. 11 05:07:21 kul3 brltty[1032]: autoreleasing key: ? (Grp:0 Num:22)
aug. 11 05:07:21 kul3 brltty[1032]: autoreleasing key: ? (Grp:0 Num:84)
aug. 11 05:07:21 kul3 brltty[1032]: autoreleasing key: ? (Grp:0 Num:85)
aug. 11 05:08:43 kul3 brltty[1032]: input byte missing at offset 0
aug. 11 05:08:43 kul3 brltty[1032]: Partial Packet: 79 54 02
aug. 11 05:09:03 kul3 brltty[1032]: autoreleasing key: ? (Grp:0 Num:22)

Thanks in advance

Lars

On Thu, Aug 10, 2017 at 10:25:29AM +0200, Mario Lang wrote:
> 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?
> 
> -- 
> CYa,
>   ⡍⠁⠗⠊⠕ | Blog: <https://blind.guru/>  GitHub: <https://github.com/mlang/>
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>