Re: USB-serial adapter suggestions needed

From: Mark Millard <marklmi_at_yahoo.com>
Date: Wed, 27 Dec 2023 08:30:26 UTC 
On Dec 26, 2023, at 18:09, bob prohaska <fbsd@www.zefox.net> wrote:

> On Tue, Dec 26, 2023 at 02:06:59AM +0100, Bernd Walter wrote:
>> On Tue, Dec 26, 2023 at 12:02:50AM +0000, Marcin Cieslak wrote:
>>> On Sun, 24 Dec 2023, bob prohaska wrote:
>>> 
>>>> I do see what looks like noise on the serial lines, but only after a spontaneous
>>>> disconnect and only with FTDI adapters. When the serial connections are working
>>>> nothing resembling noise is seen.
>>> 
>>> How does that noise look like?
>> 
> It appears to be non-ascii. I can't get it to copy and paste in a way
> that's recognizable to me, but here's a sample anyway, taken from
> bob@pelorus:~ % uname -a
> FreeBSD pelorus 14.0-RELEASE-p4 FreeBSD 14.0-RELEASE-p4 #0 releng/14.0-n265400-4edf3b80733e: Wed Dec 27 20:21:26 PST 2023     bob@pelorus:/usr/obj/usr/src/arm64.aarch64/sys/GENERIC arm64:
> .......
> # tip ucom
> connected
> 
> FreeBSD/arm64 (www.zefox.org) (ttyu1)
> 
> login: ��������
> Password:
> Login incorrect
> ..........
> 
> The backslash letter pairs are clearly different, but they're displayed on a
> RasPiOS lxterminal window as a white oval with a dark question mark in the middle.

It shows that way in some programs but not others in
my context. But what matters is the byte sequence, not
the potentially false interpretations of them.

In a program that shows hexadecimal byte values and the
printable text (with "." for control characters and for
8-bit characters on the right below):

0000: 6C 6F 67 69 6E 3A 20 C3 AF C2 BF C2 BD C3 AF C2 	login: .........
0010: BF C2 BD C3 AF C2 BF C2 BD C3 AF C2 BF C2 BD C3 	................
0020: AF C2 BF C2 BD C3 AF C2 BF C2 BD C3 AF C2 BF C2 	................
0030: BD C3 AF C2 BF C2 BD 0A 50 61 73 73 77 6F 72 64 	........Password
0040: 3A                                              	:

The byte pairs that start with C3 's and C2's look far from
random to me --also they do not look like glitches.

(Of course, I'm not looking at original files.)

> Sometimes printable characters show up, but it doesn't look like my memory
> of a baudrate mismatch on a serial modem. Maybe that's just an artifact of
> modern character sets.



===
Mark Millard
marklmi at yahoo.com