Re: serial, basic stuff

On 2024-04-21 14:45:51 (+0200), Dag-Erling Smørgrav wrote:
> Jon Clausen <freebsd-questions@ymmv.dk> writes:
> > So at this point, I should be ready to move on to attempting the setup that
> > I actually want:
> >
> > jh05:cuau1 <-> jh06:ttyu0
> >
> >
> > This does not work out of the box.
> 
> “This does not work” is not a very useful statement.

True. There's not much to report though:

root@jh05:~ # screen /dev/cuau1 115200

gets me a blank screen, and no response to keyboard input.

root@jh05:~ # cu -l /dev/cuau1 -s 115200
Connected

is functionally the same: nothing further happens, no response from either
system to keyboard input

> If you want to run the console on FreeBSD 13 or older at 115200 bps, you
> will have to add `comconsole_speed="115200"` to /boot/loader.conf and
> `-S115200` to /boot.config and reboot.

These systems are already set up with 115200, right from the installation.
I routinely connect to them with the USB-to-serial adapter from my laptop,
so I'm sure there's no issue with ttyu0 as such.

> On FreeBSD 14 and newer, it is
> already the default and you shouldn't have to change anything. 

Nice. That's good to know, but 14 is "not right now" for this setup.

> If it's
> still not working, I would suggest hooking up an oscilloscope to the
> level shifter to check that it's working properly.

Well, the oscilloscope I have is old, and I'm not convinced it even works.
But the level shifter has been working very recently, so I have high
confidence that it still is.

The thing is though, that up until now I've seen "silent non-success" every
time the parameters on either of the involved devices weren't "just right".

So I suppose I'll just have to go through everything with a fine tooth comb,
to make sure that all (stty) settings match.

br
/jon

-- 
YMMV