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Re: Sensor wiring

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Hi Mel,

On 9/30/2013 10:16 AM, 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?

Argh!  Expect to (effectively) built an I2C-to-X bridge on each end
of the line, if you are intent on a shared cable.

IME, unless you include plans for replacing the devices at one or both
ends of the line as a matter of "routine maintenance", consider an
alternative communication medium.  Opt for galvanic isolation.
[I have hundreds of "field I/O's" here and all of them are isolated
by one means or another]

Do you have *power* at both ends of the line?  Or, is power conveyed
over a similar cable?  I.e., if you can eliminate the need for a
power cable, then you have extra incentive to eliminate the *data*
cable!  :>  Alternatively, if you *do* have a power cable, you can
use it for signaling if your data rates are low enough (or you
want to spend on transceivers!)

No mention of data rates.  With smarts on each end of the line,
if your bandwidth *requirements* are low, you can opt for a
slower means of encoding them.  Do you really need bidir comms?

Consider wireless (with measures to protect the transactions if
they are "important" or "significant").  You can buy/build a small
~900MHz modem for far less than the cost of the wire + trench
digging effort.

Also consider a PLC modem -- if power to your "out building" (?)
is fed from the first building.

If intent on running some sort of "wire", first choice is optical
fiber (depending on data rates, you can often get this cheap at
surplus).

Or, transformer couple and push *audio* down the wire (possibly
even supporting duplex operation by chosing different carriers).
Look at old modem technologies for hints.

> Acknowledging that out-of-spec bits per second is a definite possiblity.

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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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