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Re: Sensor wiring

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Tim Wescott wrote:
> On Mon, 30 Sep 2013 13:16:55 -0400, Mel Wilson wrote:
>
>> I want an I2C connection between a Raspberry Pi and an ATtiny85 over 35m
>> of buried wire.  Any guidelines for signal conditioning and protection?
>> Acknowledging that out-of-spec bits per second is a definite possiblity.
>
> I really think that any work that you think you're going to avoid by
> sticking to I2C is probably vastly overshadowed by the amount of work
> that you'll need to do to make it function reliably.  This is,
> unfortunately, one of that great class of expedients that works well
> enough to fool you into thinking its a success, but tends to break in the
> presence of bosses or customers.
>
> I suspect that your best bet would be a simple asynchronous link sending
> serial commands via properly-terminated RS-422.  You'll need two twisted
> pairs (one for transmit, one for receive), but it should be dead reliable.
>
> The only thing that would drive me to retaining I2C in this case would be
> if there's some existing software that works with I2C and was very
> resistant to being rewritten to use asynchronous serial.


This.  Tim knows what he's talking about.
Most of us have scars from trying what you
want to do.

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Sensor wiring Mel Wilson <mwilson@the-wire.com> - 2013-09-30 13:16 -0400
  Re: Sensor wiring Tim Wescott <tim@seemywebsite.really> - 2013-09-30 12:39 -0500
    Re: Sensor wiring Jim Stewart <jstewart@jkmicro.com> - 2013-09-30 11:05 -0700
    Re: Sensor wiring Mel Wilson <mwilson@the-wire.com> - 2013-09-30 14:25 -0400
      Re: Sensor wiring Rob Gaddi <rgaddi@technologyhighland.invalid> - 2013-09-30 11:40 -0700
        Re: Sensor wiring Tim Wescott <tim@seemywebsite.really> - 2013-09-30 14:17 -0500
      Re: Sensor wiring Johann Klammer <klammerj@NOSPAM.a1.net> - 2013-09-30 22:30 +0200
    Re: Sensor wiring Les Cargill <lcargill99@comcast.com> - 2013-09-30 21:55 -0500
  Re: Sensor wiring Don Y <this@isnotme.com> - 2013-09-30 11:58 -0700
  Re: Sensor wiring stephenXXX@mpeforth.com (Stephen Pelc) - 2013-09-30 20:05 +0000
    Re: Sensor wiring hamilton <hamilton@nothere.com> - 2013-09-30 15:22 -0600
      Re: Sensor wiring hamilton <hamilton@nothere.com> - 2013-09-30 15:23 -0600
    Re: Sensor wiring Dave Nadler <drn@nadler.com> - 2013-10-01 13:36 -0700
    Re: Sensor wiring Dave Nadler <drn@nadler.com> - 2013-10-01 13:39 -0700
  Re: Sensor wiring Vladimir Vassilevsky <nospam@nowhere.com> - 2013-09-30 16:58 -0500
    Re: Sensor wiring Stef <stef33d@yahooI-N-V-A-L-I-D.com.invalid> - 2013-10-01 08:44 +0200
  Re: Sensor wiring upsidedown@downunder.com - 2013-10-01 10:02 +0300
    Re: Sensor wiring Tom Gardner <spamjunk@blueyonder.co.uk> - 2013-10-01 09:11 +0100
  Re: Sensor wiring Paul Rubin <no.email@nospam.invalid> - 2013-10-01 00:36 -0700
  Re: Sensor wiring Paul E Bennett <Paul_E.Bennett@topmail.co.uk> - 2013-10-01 09:19 +0100

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