Fwd: TTL/USB converter usage question

[Ramiro Aceves <ea1abz%gmail.com@localhost>]

---------- Forwarded message ---------
De: Ramiro Aceves <ea1abz%gmail.com@localhost>
Date: vie, 18 oct 2024 a las 12:26
Subject: Re: TTL/USB converter usage question
To: Michael van Elst <mlelstv%serpens.de@localhost>


El jue, 17 oct 2024 a las 7:51, Michael van Elst
(<mlelstv%serpens.de@localhost>) escribió:
>
> rvp%SDF.ORG@localhost (RVP) writes:
>
> >On Wed, 16 Oct 2024, Ramiro Aceves wrote:
>
> >> netbsd-raspa4$ { sleep 1; stty -f /dev/ttyU0 9600 raw clocal cread
> >> -crtscts; } & cat -u -v /dev/ttyU0
> >> stty: /dev/ttyU0: Resource temporarily unavailable
> >>
>
> >Wrong device--use /dev/dtyU0.
>
>
> You don't need to open the device twice and you don't need non-blocking mode.
>
> ( stty 9600 raw clocal cread -crtscts ; cat ) < /dev/dtyU0
>

Yessss!!! It works this way!

netbsd-raspa4$  ( stty 9600 raw clocal cread -crtscts ; cat ) < /dev/dtyU0

@@Ea
�
�¿½Y"�5�|6i
  3�     -�!H�
@@Ea
�
  �Y!�5�w6i�
         3�    -�!H�
^C



> will configure the interface and read from it. The dial-out device will
> avoid waiting for a carrier-detect signal, so the open is not blocked.
> Then stty disables flow control, so that cat then won't stall on the
> 3-wire connection (clocal and cread aren't necessary then, or you could
> just use clocal).
>
> The next problem is then the binary protocol. The shell won't be
> able to parse it and 'cat' will try to read big chunks. You can
> try to work around this with dd, e.g. this would read single byte
> chunks.
>
> ( stty 9600 raw clocal cread -crtscts ; dd msgfmt=quiet ibs=1 obs=1 | hexdump -vC ) < /dev/dtyU0
>
>

netbsd-raspa4$ ( stty 9600 raw clocal cread -crtscts ; dd msgfmt=quiet
ibs=1 obs=1 | hexdump -vC ) < /dev/dtyU0
00000000  0a 40 40 45 61 0a 12 07  e8 0a 15 1b 00 00 00 02  |.@@Ea...........|
00000010  08 b1 59 46 ff 35 e3 a0  00 01 36 69 00 00 00 00  |..YF.5....6i....|
00000020  00 0a 01 e8 00 00 00 0b  03 07 08 32 a2 09 08 2d  |...........2...-|
00000030  a2 04 07 21 00 00 00 00  00 00 00 00 00 00 00 00  |...!............|
00000040  00 00 00 00 00 00 00 00  00 48 34 0d 0a 40 40 45  |.........H4..@@E|
00000050  61 0a 12 07 e8 0a 15 1f  00 00 00 02 08 b1 59 49  |a.............YI|
00000060  ff 35 e3 a9 00 01 36 69  00 00 00 00 00 02 07 4a  |.5....6i.......J|
00000070  00 00 00 0b 03 07 08 33  a2 09 08 2d a2 04 07 21  |.......3...-...!|
00000080  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
^C
netbsd-raspa4$

Thanks so much Michael and all for the effort! I take my hat off to
your wisdom. It is a pleasure to have people like all of you that are
experts in all this, I am a fan that can barely defend myself using
the operating system but without knowing the ins and outs.

Regards!