Re: resetting a serial port

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How do I kill the shell session on ttyS0?

ls did nothing.
nor stty sane

but I think I saw all those characters echoed back.

On 12/14/23 00:04, Jon LaBadie wrote:
On Wed, Dec 13, 2023 at 08:45:31PM -0500, Robert Moskowitz wrote:
I have Centos 7 arm32 running on a Cubieboard and I am logged in as root
on its serial uart from another system.

On that system I use

screen /dev/ttyUSB0 115200

Well it was working well for a couple days, but now only garbage comes
across.  Something messed up the serial link.

pulling the usb cable to the usb/serial adapter does not reset things.

I can ssh into the server and see root logged into ttyS0

How do I reset that serial port so that I can work on the system?


Channeling old memories of serial communications :((

Sounds like you are still connected.  One way to tell is
to pretend things are working even if you only see garbage.

For example, if you press <Enter> several times, do you
get the same garbage each time (likely the shell prompt
coming back to you).

If after an Enter and return garbage you type ls<Enter>
is the garbage different, probably larger, and likely
ending with the same garbage as a solo <Enter> (the prompt)

Then try to reset your stty communication settings by
carefully typing

  stty sane<Enter>

Don't try to correct typo's, just hit enter and start again.

Should that not work, ssh back in and kill the shell session
on ttyS0.  Typically the communication settings are returned
to a default set by a program called getty which then exec's
into the login program.

Good luck.

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