[BRLTTY] Brltty woes on Centos 7

[Keith Wessel]

Now that makes perfect sense! I used to be a bit more of a serial geek back
in high school and my days of BBS sysoping. Other than setting up serial
consoles as an emergency console when my system won't boot so I don't have
to get my wife to read the screen to me, I don't think about it much these
days.

Sure enough, after initial boot and starting of services, ttyS0 is at 9600
baud, but it's at 19,200 when I restart brltty. Good call! Here's the sty
output after I first log in while the braille display is still not
functioning:
speed 9600 baud; line = 0;
intr = <undef>; quit = <undef>; erase = <undef>; kill = <undef>; eof =
<undef>;
start = <undef>; stop = <undef>; susp = <undef>; rprnt = <undef>;
werase = <undef>; lnext = <undef>; flush = <undef>; min = 0; time = 0;
 ignbrk -brkint -icrnl -imaxbel
 -opost -onlcr
-isig -icanon -echo -echoe -echok -echoctl -echoke

And after I stop and restart brltty, it's at 19,200 baud. I had that one
captured earlier but can't get it back at the moment because I'm out of the
office and the display's not connected, but I can get it later. I assume
brltty does some autodetecting of baud rate when it's initializing the
braille display. Is that true? Do you know if the Power Braille does
auto-detect or if it insists on 19,200?

I'm also open to suggestions how I might go about finding out what's
changing my baud rate. I'll start browsing through the system units that are
enabled; one of them must be the trouble maker.

Keith

-----Original Message-----
From: BRLTTY [mailto:brltty-bounces at brltty.com] On Behalf Of Dave Mielke
Sent: Friday, March 03, 2017 5:54 PM
To: Informal discussion between users and developers of BRLTTY.
<brltty at brltty.com>
Subject: Re: [BRLTTY] Brltty woes on Centos 7

[quoted lines by Keith Wessel on 2017/03/03 at 16:23 -0600]

>Interesting that it can't get the console control at first boot but that it

>can when I start it manually later. A timing thing, I suppose.

No, it's not all that surprising. What it means is that brltty is getting 
started so fast that all of the core devices haven't been fully set up yet.

>The braille display thing is odd. Once I get to this point where it is only
>displaying "screen not in text mode" because it couldn't get console
>control, the buttons, rather than playing their PCM tunes, generate errors
>in brltty's log. Looks like it's getting invalid data from the braille
>display. 

That, of course, is unlikely. More likely is that something has changed the 
port's baud. This is something you can query using a command like:

   stty -F /dev/ttyS0

Note that both the F and the S are uppercase. Specify the same device your 
braille device is connected to. See what it is when your braille device is 
working correctly, and then check what it is when your braille device isn't 
working correctly (I'm hoping that you're able to do that). You'll get
several 
lines of output - the baud will be on the first one. The easiest may be to 
redirect the stty command's standard output of a file.

>I've also confirmed and, as far as I can tell, Centos isn't trying to start
up 
>any serial consoles that might be conflicting.

But it may be probing the serial ports for mice, modems, etc.

-- 
Dave Mielke           | 2213 Fox Crescent | The Bible is the very Word of
God.
Phone: 1-613-726-0014 | Ottawa, Ontario   | http://Mielke.cc/bible/
EMail: Dave at Mielke.cc | Canada  K2A 1H7   | http://FamilyRadio.org/
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