Re: Two-wires RS485 and the driver enable problem

From	Grant Edwards <invalid@invalid.invalid>
Newsgroups	comp.arch.embedded
Subject	Re: Two-wires RS485 and the driver enable problem
Date	2014-10-15 14:26 +0000
Organization	PANIX Public Access Internet and UNIX, NYC
Message-ID	<m1m06e$nbm$2@reader1.panix.com> (permalink)
References	<m1geor$bt4$1@dont-email.me> <os7o3adm5pfb61gnegh1roc0sktrsgfs97@4ax.com> <n53s3ala7v59hdkeempk1hklf96ckofus7@4ax.com>

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On 2014-10-15, upsidedown@downunder.com <upsidedown@downunder.com> wrote:

> An other way of dealing with '550 style UARTs on RS-485 is to use a
> driver chip that doesn't disable the receiver during your own
> transmit. Thus the UART Rx pin will hear your transmission and the Rx
> ISR can do "echo canceling" by monitoring your own transmission. As
> soon as the Rx interrupt hears your complete final transmitted byte,
> the Rx ISR can turn off the transmit enable (RTS) and change the Rx
> mode from echo canceling to normal Rx mode.
>
> This makes it possible to do all things in the ISR and you don't have
> to do anything in normal code (with potentially bad latencies in some
> OS).

That works, but you have to disable the RX FIFO so that you get
notified of RX bytes immediatly.

-- 
Grant Edwards               grant.b.edwards        Yow! Everybody is going
                                  at               somewhere!!  It's probably
                              gmail.com            a garage sale or a disaster
                                                   Movie!!

Thread

Two-wires RS485 and the driver enable problem pozzugno <pozzugno@gmail.com> - 2014-10-13 13:58 +0200
  Re: Two-wires RS485 and the driver enable problem Wouter van Ooijen <wouter@voti.nl> - 2014-10-13 14:29 +0200
    Re: Two-wires RS485 and the driver enable problem pozzugno <pozzugno@gmail.com> - 2014-10-13 14:38 +0200
      Re: Two-wires RS485 and the driver enable problem Wouter van Ooijen <wouter@voti.nl> - 2014-10-13 15:28 +0200
        Re: Two-wires RS485 and the driver enable problem Don Y <this@is.not.me.com> - 2014-10-13 07:21 -0700
          Re: Two-wires RS485 and the driver enable problem Wouter van Ooijen <wouter@voti.nl> - 2014-10-13 16:46 +0200
            Re: Two-wires RS485 and the driver enable problem Don Y <this@is.not.me.com> - 2014-10-13 08:02 -0700
        Re: Two-wires RS485 and the driver enable problem pozzugno <pozzugno@gmail.com> - 2014-10-13 16:59 +0200
          Re: Two-wires RS485 and the driver enable problem Don Y <this@is.not.me.com> - 2014-10-13 08:08 -0700
            Re: Two-wires RS485 and the driver enable problem pozz <pozzugno@gmail.com> - 2014-10-14 07:48 +0200
              Re: Two-wires RS485 and the driver enable problem Don Y <this@is.not.me.com> - 2014-10-13 23:28 -0700
                Re: Two-wires RS485 and the driver enable problem pozzugno <pozzugno@gmail.com> - 2014-10-14 09:20 +0200
                Re: Two-wires RS485 and the driver enable problem Don Y <this@is.not.me.com> - 2014-10-14 06:09 -0700
              Re: Two-wires RS485 and the driver enable problem David Brown <david.brown@hesbynett.no> - 2014-10-14 10:36 +0200
          Re: Two-wires RS485 and the driver enable problem Wouter van Ooijen <wouter@voti.nl> - 2014-10-13 18:14 +0200
      Re: Two-wires RS485 and the driver enable problem Tim Wescott <seemywebsite@myfooter.really> - 2014-10-13 16:30 -0500
  Re: Two-wires RS485 and the driver enable problem David Brown <david.brown@hesbynett.no> - 2014-10-13 14:47 +0200
    Re: Two-wires RS485 and the driver enable problem pozzugno <pozzugno@gmail.com> - 2014-10-13 14:56 +0200
      Re: Two-wires RS485 and the driver enable problem David Brown <david.brown@hesbynett.no> - 2014-10-13 16:13 +0200
      Re: Two-wires RS485 and the driver enable problem Don Y <this@is.not.me.com> - 2014-10-13 08:06 -0700
        Re: Two-wires RS485 and the driver enable problem pozzugno <pozzugno@gmail.com> - 2014-10-14 08:50 +0200
          Re: Two-wires RS485 and the driver enable problem Don Y <this@is.not.me.com> - 2014-10-14 14:34 -0700
  Re: Two-wires RS485 and the driver enable problem Richard Damon <Richard@Damon-Family.org> - 2014-10-13 09:11 -0400
  Re: Two-wires RS485 and the driver enable problem rickman <gnuarm@gmail.com> - 2014-10-13 10:53 -0400
    Re: Two-wires RS485 and the driver enable problem pozzugno <pozzugno@gmail.com> - 2014-10-13 17:03 +0200
  Re: Two-wires RS485 and the driver enable problem Grant Edwards <invalid@invalid.invalid> - 2014-10-13 15:20 +0000
    Re: Two-wires RS485 and the driver enable problem pozzugno <pozzugno@gmail.com> - 2014-10-16 09:01 +0200
      Re: Two-wires RS485 and the driver enable problem Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2014-10-16 10:19 +0300
      Re: Two-wires RS485 and the driver enable problem rickman <gnuarm@gmail.com> - 2014-10-16 05:02 -0400
  Re: Two-wires RS485 and the driver enable problem Don Y <this@is.not.me.com> - 2014-10-13 08:17 -0700
    Re: Two-wires RS485 and the driver enable problem Don Y <this@is.not.me.com> - 2014-10-13 08:19 -0700
    Re: Two-wires RS485 and the driver enable problem pozzugno <pozzugno@gmail.com> - 2014-10-14 09:28 +0200
      Re: Two-wires RS485 and the driver enable problem Don Y <this@is.not.me.com> - 2014-10-14 06:09 -0700
        Re: Two-wires RS485 and the driver enable problem rickman <gnuarm@gmail.com> - 2014-10-14 14:28 -0400
    Re: Two-wires RS485 and the driver enable problem rickman <gnuarm@gmail.com> - 2014-10-14 04:36 -0400
  Re: Two-wires RS485 and the driver enable problem Les Cargill <lcargill99@comcast.com> - 2014-10-13 12:35 -0500
    Re: Two-wires RS485 and the driver enable problem langwadt@fonz.dk - 2014-10-13 15:02 -0700
      Re: Two-wires RS485 and the driver enable problem Don Y <this@is.not.me.com> - 2014-10-13 17:36 -0700
        Re: Two-wires RS485 and the driver enable problem Les Cargill <lcargill99@comcast.com> - 2014-10-13 21:53 -0500
          Re: Two-wires RS485 and the driver enable problem Don Y <this@is.not.me.com> - 2014-10-13 20:24 -0700
  Re: Two-wires RS485 and the driver enable problem upsidedown@downunder.com - 2014-10-13 22:02 +0300
    Re: Two-wires RS485 and the driver enable problem Grant Edwards <invalid@invalid.invalid> - 2014-10-13 19:09 +0000
      Re: Two-wires RS485 and the driver enable problem glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2014-10-13 20:58 +0000
        Re: Two-wires RS485 and the driver enable problem Grant Edwards <invalid@invalid.invalid> - 2014-10-13 21:08 +0000
          Re: Two-wires RS485 and the driver enable problem langwadt@fonz.dk - 2014-10-13 14:40 -0700
    Re: Two-wires RS485 and the driver enable problem Dave Nadler <drn@nadler.com> - 2014-10-14 09:58 -0700
      Re: Two-wires RS485 and the driver enable problem rickman <gnuarm@gmail.com> - 2014-10-14 14:20 -0400
        Re: Two-wires RS485 and the driver enable problem David Brown <david.brown@hesbynett.no> - 2014-10-14 23:35 +0200
          Re: Two-wires RS485 and the driver enable problem rickman <gnuarm@gmail.com> - 2014-10-15 02:00 -0400
            Re: Two-wires RS485 and the driver enable problem David Brown <david.brown@hesbynett.no> - 2014-10-15 09:47 +0200
              Re: Two-wires RS485 and the driver enable problem rickman <gnuarm@gmail.com> - 2014-10-16 01:30 -0400
                Re: Two-wires RS485 and the driver enable problem David Brown <david.brown@hesbynett.no> - 2014-10-16 20:46 +0200
                Re: Two-wires RS485 and the driver enable problem Dave Nadler <drn@nadler.com> - 2014-10-16 12:00 -0700
            Re: Two-wires RS485 and the driver enable problem upsidedown@downunder.com - 2014-10-15 11:01 +0300
            Re: Two-wires RS485 and the driver enable problem Grant Edwards <invalid@invalid.invalid> - 2014-10-15 14:24 +0000
              Re: Two-wires RS485 and the driver enable problem rickman <gnuarm@gmail.com> - 2014-10-16 01:17 -0400
                Re: Two-wires RS485 and the driver enable problem pozzugno <pozzugno@gmail.com> - 2014-10-16 08:36 +0200
                Re: Two-wires RS485 and the driver enable problem rickman <gnuarm@gmail.com> - 2014-10-16 05:05 -0400
                Re: Two-wires RS485 and the driver enable problem pozzugno <pozzugno@gmail.com> - 2014-10-16 12:54 +0200
                Re: Two-wires RS485 and the driver enable problem Grant Edwards <invalid@invalid.invalid> - 2014-10-16 14:16 +0000
    Re: Two-wires RS485 and the driver enable problem upsidedown@downunder.com - 2014-10-15 09:09 +0300
      Re: Two-wires RS485 and the driver enable problem Grant Edwards <invalid@invalid.invalid> - 2014-10-15 14:26 +0000
  Re: Two-wires RS485 and the driver enable problem glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2014-10-13 20:55 +0000
  Re: Two-wires RS485 and the driver enable problem Tim Wescott <seemywebsite@myfooter.really> - 2014-10-13 16:37 -0500
    Re: Two-wires RS485 and the driver enable problem pozzugno <pozzugno@gmail.com> - 2014-10-14 09:37 +0200
  Re: Two-wires RS485 and the driver enable problem Arlet Ottens <usenet+5@c-scape.nl> - 2014-10-14 20:44 +0200

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