[BRLTTY] Using the Orbit Reader 20 with BRLTTY and Orca

[Dave Mielke]

[quoted lines by Nolan Darilek on 2019/06/05 at 18:10 -0500]

>Hey, just picked up one of these recently and had a few questions. I've
>gotten it intermittently working with BRLTTY, 

What, exactly, is being intermittent? When it works, does everything work? When
it doesn't work, does nothing at all work? How often does it work versus fail?

>but not at all with Orca. 

Perhaps you aren't telling Orca to use brltty as its braille driver. Perhaps
the BrlAPI interface isn't properly enabled. Guessing is never good. We'd need
to see a log.

>1. The Orbit has two modes that seem relevant to BRLTTY use:: Serial and HID.
>I assume I want to use serial mode?

Both should work, assuming, of course, that you're using the Bam (bm) driver.

>2. What is the process for using the Orbit with BRLTTY if I'll be plugging
>and unplugging it fairly regularly? Specifically:
>
>a) I'm using BRLTTY with systemd. Can I leave the service running,
>connect/disconnect the unit, and expect to have that change noticed? Or will
>I need to restart the service whenever reconnecting?

If you have the latest brltty udev rules installed properly, and if you have
the latest brltty systemd units installed properly, then you just need to
connect/disconnect your braille device. Assumimg a USB connection, the acts of
connecting and disconnecting the braille deivce will automatically take care of
starting and stopping brltty.

>b) Do I need to do something on the unit itself, other than
>connecting/starting the unit, to get output? 

No, you shouldn't need to. Of course, you'll need to ensure that it isn't in
some sort of internal use mode and that it's configured to use the I/O method
that you're connecting it with.

>I'm getting an alert about the screen not being in text mode, which makes
>sense since I'm in X.

Yes. Try switching to a text console in order to verify that brltty itself is
indeed working correctly.

>But I only get that message sometimes, and it doesn't always appear after I've
>plugged in the unit, enabled serial mode, and restarted the systemd service.

I'm not willing to guess. We need to figure out exactly what is and isn't
working. Please capture a debug log. You can do this most easily by adding two
command line options when invoking brltty. They are:

   -ldebug,brldrv,inpkts,outpkts,usb
   -L/path/to/logfile

Note that the first -l is lowercase and that the second -L is uppercase.

>c) Can BRLTTY handle its configured device node appearing/disappearing?

Yes.

>3. My unit seems to use /dev/ttyACM0, not /dev/ttyUSB0. What does ACM mean in
>this context?

The ttyUSB devices are for various (usually older) USB to serial adapters. The
ttyACM devices are for the ones that conform to the ACM (Abstract Control
Model) subclass of the CDC (Communication Device Class). This newer standard is
generic, and, therefore, a bit more complex so it presents the serial adapter
to the system in a way that's different enough to warrant its own kernel
driver.

Now I'm getting the idea that you're asking brltty to use its serial I/O
paradigm, i.e. something like serial:ttyACM0, which won't adequately interact
with systemd. It'd be better, I think, to tell brltty to access the device via
USB directly, i.e. specifying usb: (yes, the trailing colon is necessary).
That's what brltty's udev rules would do automatically for you.

>4. How do I use BRLTTY with Orca? I'm on Fedora 29. I've installed the brlapi
>package and added:
>
>api-parameters Auth=group:brlapi        # Allow some local group
>
>and my user is in the brlapi group. 

But is Orca running as a process which can be a member of that group.

When trying to figure this sort of thing out, it's best to simplify the usage
first and then slowly, one step at a time, getting back to where you want to
be. That, for example, is why, above, I suggested that you first verify that
brltty is working correctly within a text console. For this case, my suggestion
is to first try with auth:none.

You may also wish to consider using BrlAPI's polkit support.

>I've enabled Braille in Orca, and have restarted.

Have you set Orca's braille driver to brltty?

>5. I see lots of this in my logs. What does it mean?
>
>Jun 05 18:06:00 desktop systemd[1]: Starting Braille display driver for Linux/Unix...

That's when systemd is starting brltty.

>Jun 05 18:06:00 desktop brltty[18771]: BRLTTY 5.6 rev unknown [http://brltty.com/

And that's brltty actually starting. The "unknown" means that brltty was built
outside of a git source tree so the build couldn't figure out which revision of
the source was being used.

>Jun 05 18:06:00 desktop brltty[18771]: BRLTTY 5.6 rev unknown [http://brltty.com/]

If you're actually seeing this twice then it's because one is from brltty
logging its banner to the system log and the other is brltty writing its banner
to the console (which systemd must be including within its journal).

>Jun 05 18:06:00 desktop systemd[1]: Started Braille display driver for Linux/Unix.

That's systemd confirming that brltty has been started.

>Jun 05 18:06:00 desktop brltty[18772]: NoSpeech Speech Driver:

That means that you aren't using any of brltty's speech drivers.

>Jun 05 18:06:04 desktop brltty[18772]: Ignored Byte: 1B
>Jun 05 18:06:04 desktop brltty[18772]: Ignored Byte: 34
>Jun 05 18:06:04 desktop brltty[18772]: Ignored Byte: 04
>Jun 05 18:06:04 desktop brltty[18772]: Ignored Byte: 1B
>Jun 05 18:06:04 desktop brltty[18772]: Ignored Byte: 34

This is the braille driver ignoring Baum-style packets, which is making me
wonder if you're using a different driver.

-- 
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
Phone: +1 613 726 0014 | Canada  K2A 1H7   |