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Re: Linux embedded and direction control of RS485 transceiver

From "A.P.Richelieu" <aprichelieu@gmail.com>
Newsgroups comp.arch.embedded
Subject Re: Linux embedded and direction control of RS485 transceiver
Date 2021-05-09 13:24 +0200
Organization Aioe.org NNTP Server
Message-ID <s78gpc$o3d$1@gioia.aioe.org> (permalink)
References <s3ds9e$k43$1@dont-email.me>

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Den 2021-03-24 kl. 00:06, skrev pozz:
> I have an half-duplex RS485 bus with 10-20 different nodes. Some of them 
> are 8-bit MCU based, one of them could be Linux embedded.
> 
> It's half-duplex, so it's important for the transmitter node to disable 
> the driver as soon as the last transmitted bit is shifted out.
> 
> Many small low-cost MCU has interrupt on transmission complete, so the 
> delay of disabling the driver is usually on the order of microseconds.
> 
> Some new Cortex-M MCUs have an automatic control of external RS485 
> transceiver, so the delay is really zero.
> 
> What happens in Linux embedded systems? Many of them are based on NXP 
> i.MX CPUs and it seems they aren't able to control the RS485 direction 
> in hardware, but some code is needed. This approach could increase the 
> delay of disabling the driver in the order of milliseconds.
> 
> Is it possible that a powerful CPU isn't able to control RS485 driver in 
> hardware?

Atmel (now Microchip) ARM products has a serial port which supports 
handling the RS-485 direction in hardware. It also has an interrupt
which is triggered after a programmable delay has occured without any
receied characters.

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Thread

Linux embedded and direction control of RS485 transceiver pozz <pozzugno@gmail.com> - 2021-03-24 00:06 +0100
  Re: Linux embedded and direction control of RS485 transceiver upsidedown@downunder.com - 2021-03-24 07:28 +0200
    Re: Linux embedded and direction control of RS485 transceiver Don Y <blockedofcourse@foo.invalid> - 2021-03-24 06:17 -0700
      Re: Linux embedded and direction control of RS485 transceiver upsidedown@downunder.com - 2021-03-24 17:49 +0200
        Re: Linux embedded and direction control of RS485 transceiver Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2021-03-24 18:32 +0200
          Re: Linux embedded and direction control of RS485 transceiver upsidedown@downunder.com - 2021-03-24 19:22 +0200
            Re: Linux embedded and direction control of RS485 transceiver David Brown <david.brown@hesbynett.no> - 2021-03-24 19:44 +0100
              Re: Linux embedded and direction control of RS485 transceiver upsidedown@downunder.com - 2021-03-25 07:34 +0200
              Re: Linux embedded and direction control of RS485 transceiver upsidedown@downunder.com - 2021-03-25 07:47 +0200
            Re: Linux embedded and direction control of RS485 transceiver Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2021-03-24 21:13 +0200
              Re: Linux embedded and direction control of RS485 transceiver upsidedown@downunder.com - 2021-03-25 07:39 +0200
              Re: Linux embedded and direction control of RS485 transceiver David Brown <david.brown@hesbynett.no> - 2021-03-25 10:48 +0100
                Re: Linux embedded and direction control of RS485 transceiver Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2021-03-25 16:33 +0200
                Re: Linux embedded and direction control of RS485 transceiver Grant Edwards <invalid@invalid.invalid> - 2021-03-25 14:49 +0000
                Re: Linux embedded and direction control of RS485 transceiver upsidedown@downunder.com - 2021-03-25 18:43 +0200
                Re: Linux embedded and direction control of RS485 transceiver David Brown <david.brown@hesbynett.no> - 2021-03-26 09:47 +0100
        Re: Linux embedded and direction control of RS485 transceiver Don Y <blockedofcourse@foo.invalid> - 2021-03-24 14:30 -0700
  Re: Linux embedded and direction control of RS485 transceiver dalai lamah <antonio12358@hotmail.com> - 2021-03-24 11:48 +0100
    Re: Linux embedded and direction control of RS485 transceiver pozz <pozzugno@gmail.com> - 2021-03-25 00:23 +0100
  Re: Linux embedded and direction control of RS485 transceiver "A.P.Richelieu" <aprichelieu@gmail.com> - 2021-05-09 13:24 +0200
    Re: Linux embedded and direction control of RS485 transceiver Uwe Bonnes <bon@hertz.ikp.physik.tu-darmstadt.de> - 2021-05-09 12:01 +0000
    Re: Linux embedded and direction control of RS485 transceiver pozz <pozzugno@gmail.com> - 2021-05-10 09:46 +0200

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