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Groups > comp.arch.embedded > #31565

Re: Boxed MCU with RS-232 Port

From Andrew Smallshaw <andrews@sdf.org>
Newsgroups comp.arch.embedded
Subject Re: Boxed MCU with RS-232 Port
Date 2023-01-18 13:22 +0000
Organization A noiseless patient Spider
Message-ID <slrntsfsk6.hjt.andrews@sdf.org> (permalink)
References (4 earlier) <2b3941b6-1a59-412c-b088-29794ac047b3n@googlegroups.com> <878ri0vmvg.fsf@nightsong.com> <d5419959-247d-4162-9ae4-bdabfe1c7e01n@googlegroups.com> <slrntsfonr.9sa.andrews@sdf.org> <4fa9560b-f1c6-4634-ab99-f9b1ae33531an@googlegroups.com>

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On 2023-01-18, Rick C <gnuarm.deletethisbit@gmail.com> wrote:
>
> The data sheet I saw has a table of minimum capacitance for three
> Vcc ranges, 3.3V, 5V and 3.3 to 5V approximately.  Only 3.3V was
> 0.1 uF on all caps.  The others were larger on at least one cap.
> Table 9-1 on page 12.  1

I'm reading Maxim's datasheet, see
https://pdf1.alldatasheet.com/datasheet-pdf/view/73152/MAXIM/MAX3232CPE.html
If you're looking at a sheet from another manufacturer that may
change, leading to the same kind of incompatibility as seen with
the MAX232 variants.

> You mean the RS-232 (TIA/EIAI) specification has changed?  I have
> not seen this.

Not recently but over time, yes.  From memory the initial spec was
+/-12V.  I think it was RS232C that lowered it to +/-9V but don't
hold me to that.  It was either RS232E or F that lowered it again
to +/-5V.  Even the 'F' revision is fairly old now, but 'C' got so
deeply ingrained it's not unusual to see references to RS232C even
today.  All specify inputs must tolerate up to +/-25V so there is
cross-compatibility in terms of avoiding damage at least, but RS232
is one of those standards that often doesn't get implemented rigidly,
e.g. power thieves, discrete implementations that are not strictly
compliant, and so on.

> 5V supply.  I don't know why you are talking about the MAX232.
> I've said "MAX3232CPE" several times.

Acknowledged. MAX232 is the classic part for this application and
where I suspect most people will have gained their initial experience.
It's the one that has the most issue with the cap sizing.  It's
also a 5V only part.  The MAX2323 is a 3.3V/5V part, at 5V it's
interchangable with the MAX232 but the latter has higher output
levels.  If thresholds are the marginal factor here that's why I
suggest it as a possible experiment.

-- 
Andrew Smallshaw
andrews@sdf.org

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Thread

Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-01-17 07:24 -0800
  Re: Boxed MCU with RS-232 Port Paul Rubin <no.email@nospam.invalid> - 2023-01-17 11:31 -0800
    Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-01-17 12:19 -0800
      Re: Boxed MCU with RS-232 Port Paul Rubin <no.email@nospam.invalid> - 2023-01-17 13:07 -0800
        Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-01-17 13:29 -0800
          Re: Boxed MCU with RS-232 Port Paul Rubin <no.email@nospam.invalid> - 2023-01-17 14:04 -0800
            Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-01-17 14:47 -0800
              Re: Boxed MCU with RS-232 Port Paul Rubin <no.email@nospam.invalid> - 2023-01-17 15:32 -0800
                Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-01-17 15:44 -0800
                Re: Boxed MCU with RS-232 Port Paul Rubin <no.email@nospam.invalid> - 2023-01-17 16:04 -0800
                Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-01-17 17:32 -0800
                Re: Boxed MCU with RS-232 Port Paul Rubin <no.email@nospam.invalid> - 2023-01-17 20:02 -0800
                Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-01-17 20:24 -0800
                Re: Boxed MCU with RS-232 Port Paul Rubin <no.email@nospam.invalid> - 2023-01-17 20:56 -0800
                Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-01-17 22:30 -0800
                Re: Boxed MCU with RS-232 Port Paul Rubin <no.email@nospam.invalid> - 2023-01-18 00:37 -0800
                Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-01-18 04:43 -0800
                Re: Boxed MCU with RS-232 Port Paul Rubin <no.email@nospam.invalid> - 2023-01-18 14:19 -0800
                Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-01-18 23:15 -0800
                Re: Boxed MCU with RS-232 Port Paul Rubin <no.email@nospam.invalid> - 2023-01-19 12:21 -0800
              Re: Boxed MCU with RS-232 Port Andrew Smallshaw <andrews@sdf.org> - 2023-01-18 12:15 +0000
                Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-01-18 04:55 -0800
                Re: Boxed MCU with RS-232 Port Andrew Smallshaw <andrews@sdf.org> - 2023-01-18 13:22 +0000
                Re: Boxed MCU with RS-232 Port Andrew Smallshaw <andrews@sdf.org> - 2023-01-18 13:28 +0000
                Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-01-18 06:20 -0800
      Re: Boxed MCU with RS-232 Port David Brown <david.brown@hesbynett.no> - 2023-01-18 10:04 +0100
  Re: Boxed MCU with RS-232 Port Theo <theom+news@chiark.greenend.org.uk> - 2023-01-18 16:18 +0000
    Re: Boxed MCU with RS-232 Port Paul Rubin <no.email@nospam.invalid> - 2023-01-18 14:10 -0800
      Re: Boxed MCU with RS-232 Port Theo <theom+news@chiark.greenend.org.uk> - 2023-01-19 10:29 +0000
        Re: Boxed MCU with RS-232 Port Don Y <blockedofcourse@foo.invalid> - 2023-01-19 05:41 -0700
          Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-01-19 10:00 -0800
            Re: Boxed MCU with RS-232 Port Paul Rubin <no.email@nospam.invalid> - 2023-01-19 12:42 -0800
              Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-01-19 14:10 -0800
                Re: Boxed MCU with RS-232 Port Paul Rubin <no.email@nospam.invalid> - 2023-01-19 16:16 -0800
        Re: Boxed MCU with RS-232 Port Grant Edwards <invalid@invalid.invalid> - 2023-01-19 16:07 +0000
          Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-01-19 10:13 -0800
          Re: Boxed MCU with RS-232 Port Don Y <blockedofcourse@foo.invalid> - 2023-01-19 14:51 -0700
        Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-01-19 10:06 -0800
          Re: Boxed MCU with RS-232 Port Theo <theom+news@chiark.greenend.org.uk> - 2023-01-20 13:03 +0000
            Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-01-20 06:28 -0800
            Re: Boxed MCU with RS-232 Port Paul Rubin <no.email@nospam.invalid> - 2023-01-20 19:14 -0800
              Re: Boxed MCU with RS-232 Port Don Y <blockedofcourse@foo.invalid> - 2023-01-20 20:41 -0700
                Re: Boxed MCU with RS-232 Port Don Y <blockedofcourse@foo.invalid> - 2023-01-21 05:05 -0700
              Re: Boxed MCU with RS-232 Port Theo <theom+news@chiark.greenend.org.uk> - 2023-01-21 10:53 +0000
          Re: Boxed MCU with RS-232 Port Herbert Kleebauer <klee@unibwm.de> - 2023-01-20 19:17 +0100
            Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-01-20 12:37 -0800
              Re: Boxed MCU with RS-232 Port Dimiter_Popoff <dp@tgi-sci.com> - 2023-01-20 23:02 +0200
                Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-01-20 14:08 -0800
                Re: Boxed MCU with RS-232 Port Dimiter_Popoff <dp@tgi-sci.com> - 2023-01-21 01:38 +0200
                Re: Boxed MCU with RS-232 Port antispam@math.uni.wroc.pl - 2023-01-21 01:58 +0000
                Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-01-20 18:44 -0800
                Re: Boxed MCU with RS-232 Port antispam@math.uni.wroc.pl - 2023-01-21 20:02 +0000
                Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-01-22 17:12 -0800
                Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-02-03 09:22 -0800
                Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-02-03 10:04 -0800
                Re: Boxed MCU with RS-232 Port Dimiter_Popoff <dp@tgi-sci.com> - 2023-03-26 22:24 +0300
                Re: Boxed MCU with RS-232 Port Don Y <blockedofcourse@foo.invalid> - 2023-03-27 02:27 -0700
  Re: Boxed MCU with RS-232 Port pozz <pozzugno@gmail.com> - 2023-01-20 08:54 +0100
    Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-01-20 01:03 -0800
  Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-22 12:18 -0700
    Re: Boxed MCU with RS-232 Port Paul Rubin <no.email@nospam.invalid> - 2023-03-22 20:35 -0700
      Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-22 23:26 -0700
        Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-22 23:28 -0700
          Re: Boxed MCU with RS-232 Port Theo <theom+news@chiark.greenend.org.uk> - 2023-03-23 10:06 +0000
            Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-24 00:59 -0700
          Re: Boxed MCU with RS-232 Port Paul Rubin <no.email@nospam.invalid> - 2023-03-23 09:00 -0700
            Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-24 01:03 -0700
        Re: Boxed MCU with RS-232 Port Paul Rubin <no.email@nospam.invalid> - 2023-03-23 08:54 -0700
          Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-24 01:02 -0700
            Re: Boxed MCU with RS-232 Port Paul Rubin <no.email@nospam.invalid> - 2023-03-24 01:43 -0700
            Re: Boxed MCU with RS-232 Port Hans-Bernhard Bröker <HBBroeker@t-online.de> - 2023-03-24 12:44 +0100
              Re: Boxed MCU with RS-232 Port Theo <theom+news@chiark.greenend.org.uk> - 2023-03-24 14:20 +0000
                Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-24 08:08 -0700
                Re: Boxed MCU with RS-232 Port Theo <theom+news@chiark.greenend.org.uk> - 2023-03-24 16:23 +0000
                Re: Boxed MCU with RS-232 Port Paul Rubin <no.email@nospam.invalid> - 2023-03-24 13:42 -0700
                Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-24 14:31 -0700
                Re: Boxed MCU with RS-232 Port Paul Rubin <no.email@nospam.invalid> - 2023-03-24 18:19 -0700
                Re: Boxed MCU with RS-232 Port Paul Rubin <no.email@nospam.invalid> - 2023-03-24 18:22 -0700
                Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-24 18:34 -0700
                Re: Boxed MCU with RS-232 Port Paul Rubin <no.email@nospam.invalid> - 2023-03-24 19:43 -0700
                Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-24 20:01 -0700
                Re: Boxed MCU with RS-232 Port Paul Rubin <no.email@nospam.invalid> - 2023-03-24 21:18 -0700
                Re: Boxed MCU with RS-232 Port Don Y <blockedofcourse@foo.invalid> - 2023-03-24 15:35 -0700
                Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-24 18:21 -0700
                Re: Boxed MCU with RS-232 Port Don Y <blockedofcourse@foo.invalid> - 2023-03-24 19:21 -0700
                Re: Boxed MCU with RS-232 Port George Neuner <gneuner2@comcast.net> - 2023-03-25 21:42 -0400
                Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-25 19:26 -0700
                Re: Boxed MCU with RS-232 Port Jim Jackson <jj@franjam.org.uk> - 2023-03-26 18:27 +0000
                Re: Boxed MCU with RS-232 Port Don Y <blockedofcourse@foo.invalid> - 2023-03-26 13:23 -0700
                Re: Boxed MCU with RS-232 Port Don Y <blockedofcourse@foo.invalid> - 2023-03-26 13:32 -0700
                Re: Boxed MCU with RS-232 Port Don Y <blockedofcourse@foo.invalid> - 2023-03-26 13:52 -0700
                Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-26 19:30 -0700
                Re: Boxed MCU with RS-232 Port Don Y <blockedofcourse@foo.invalid> - 2023-03-26 20:31 -0700
                Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-27 07:04 -0700
                Re: Boxed MCU with RS-232 Port Don Y <blockedofcourse@foo.invalid> - 2023-03-27 09:21 -0700
                Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-27 09:56 -0700
                Re: Boxed MCU with RS-232 Port Don Y <blockedofcourse@foo.invalid> - 2023-03-27 13:08 -0700
                Re: Boxed MCU with RS-232 Port Jim Jackson <jj@franjam.org.uk> - 2023-03-27 20:46 +0000
                Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-27 15:07 -0700
                Re: Boxed MCU with RS-232 Port Don Y <blockedofcourse@foo.invalid> - 2023-03-27 15:07 -0700
                Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-27 14:50 -0700
                Re: Boxed MCU with RS-232 Port Don Y <blockedofcourse@foo.invalid> - 2023-03-27 15:07 -0700
                Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-27 15:24 -0700
                Re: Boxed MCU with RS-232 Port Don Y <blockedofcourse@foo.invalid> - 2023-03-27 15:36 -0700
                Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-27 15:37 -0700
                Re: Boxed MCU with RS-232 Port Don Y <blockedofcourse@foo.invalid> - 2023-03-27 15:42 -0700
                Re: Boxed MCU with RS-232 Port David Brown <david.brown@hesbynett.no> - 2023-03-27 11:03 +0200
                Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-27 07:11 -0700
                Re: Boxed MCU with RS-232 Port Dimiter_Popoff <dp@tgi-sci.com> - 2023-03-27 17:47 +0300
                Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-27 08:05 -0700
                Re: Boxed MCU with RS-232 Port Dimiter_Popoff <dp@tgi-sci.com> - 2023-03-27 19:09 +0300
                Re: Boxed MCU with RS-232 Port David Brown <david.brown@hesbynett.no> - 2023-03-27 17:38 +0200
                Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-26 19:22 -0700
                Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-26 19:11 -0700
                Re: Boxed MCU with RS-232 Port Don Y <blockedofcourse@foo.invalid> - 2023-03-26 13:37 -0700
                Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-26 19:28 -0700
                Re: Boxed MCU with RS-232 Port Don Y <blockedofcourse@foo.invalid> - 2023-03-27 13:38 -0700
                Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-27 15:05 -0700
                Re: Boxed MCU with RS-232 Port Don Y <blockedofcourse@foo.invalid> - 2023-03-27 15:08 -0700
                Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-27 15:25 -0700
                Re: Boxed MCU with RS-232 Port Don Y <blockedofcourse@foo.invalid> - 2023-03-27 15:38 -0700
                Re: Boxed MCU with RS-232 Port Don Y <blockedofcourse@foo.invalid> - 2023-03-26 13:23 -0700
                Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-26 19:25 -0700
                Re: Boxed MCU with RS-232 Port Don Y <blockedofcourse@foo.invalid> - 2023-03-26 20:31 -0700
                Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-27 07:05 -0700
                Re: Boxed MCU with RS-232 Port Don Y <blockedofcourse@foo.invalid> - 2023-03-27 09:18 -0700
                Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-27 10:09 -0700
                Re: Boxed MCU with RS-232 Port Don Y <blockedofcourse@foo.invalid> - 2023-03-27 12:16 -0700
                Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-27 13:03 -0700
                Re: Boxed MCU with RS-232 Port Don Y <blockedofcourse@foo.invalid> - 2023-03-27 13:17 -0700
                Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-27 15:05 -0700
                Re: Boxed MCU with RS-232 Port Don Y <blockedofcourse@foo.invalid> - 2023-03-27 15:40 -0700
                Re: Boxed MCU with RS-232 Port Clifford Heath <no.spam@please.net> - 2023-03-28 10:36 +1100
                Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-27 17:59 -0700
                Re: Boxed MCU with RS-232 Port Clifford Heath <no.spam@please.net> - 2023-03-28 12:58 +1100
                Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-27 20:41 -0700
                Re: Boxed MCU with RS-232 Port Clifford Heath <no.spam@please.net> - 2023-03-28 15:21 +1100
                Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-28 08:37 -0700
                Re: Boxed MCU with RS-232 Port Jim Jackson <jj@franjam.org.uk> - 2023-03-28 20:00 +0000
                Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-28 13:06 -0700
                Re: Boxed MCU with RS-232 Port Clifford Heath <no.spam@please.net> - 2023-03-29 08:03 +1100
                Re: Boxed MCU with RS-232 Port Don Y <blockedofcourse@foo.invalid> - 2023-03-28 00:11 -0700
                Re: Boxed MCU with RS-232 Port "b...@gmx.com" <bl1@gmx.com> - 2023-03-27 16:17 -0700
                Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-27 18:12 -0700
                Re: Boxed MCU with RS-232 Port Hans-Bernhard Bröker <HBBroeker@t-online.de> - 2023-03-24 19:26 +0100
              Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-24 08:03 -0700
                Re: Boxed MCU with RS-232 Port Hans-Bernhard Bröker <HBBroeker@t-online.de> - 2023-03-24 19:10 +0100
    Re: Boxed MCU with RS-232 Port Herbert Kleebauer <klee@unibwm.de> - 2023-03-24 17:16 +0100
      Re: Boxed MCU with RS-232 Port Herbert Kleebauer <klee@unibwm.de> - 2023-03-24 18:54 +0100
      Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-24 11:34 -0700
  Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-27 10:18 -0700
  Re: Boxed MCU with RS-232 Port Uwe Bonnes <bon@hertz.ikp.physik.tu-darmstadt.de> - 2023-03-28 20:53 +0000
    Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-28 16:12 -0700
      Re: Boxed MCU with RS-232 Port Niklas Holsti <niklas.holsti@tidorum.invalid> - 2023-03-29 09:06 +0300
        Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-29 00:44 -0700

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