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Re: Sensor wiring

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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.
> 
> Thanks,		Mel.

Hi Mel,

I have just seen this and note you already had quite a few responses.

The sort of distance you are going I would definitely say that I2C is not 
the long range interconnect you ould want. Galvanic Isolation and Transient 
Protection is going to be required for both ends of the link.

If you also need power fed to the instrument end then this has also to be 
figured in and similarly protected if it is other than a mains supply. In 
which case I would look at either opto-isolator or transformer coupled 
connections. It is easy to recreate the I2C electrical conditions at each 
end of the isolated link. What you use in between should be given careful 
consideration but just raising the voltage level of the signals and 
employing appropriate protective zener/varistor/capacitor clamping and 
filtering with energy controlling resistors will be the route I would take.

You can use a cable with a screened twisted pair for each line and even a 
third one for the low-power feed if you need it (3 pair cable by Belden 
would probably suit if you have a suitable conduit for the cable to go 
through). 

If you had mentioned the sort of data rate you were interested in it would 
have been easier to suggest something more specific.

-- 
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Paul E. Bennett IEng MIET.....<email://Paul_E.Bennett@topmail.co.uk>
Forth based HIDECS Consultancy.............<http://www.hidecs.co.uk>
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Thread

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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