user1414: I am looking for a multi-purpose wire protocol for Arduino.
Requirements:

Range of at least 500ft (200m)
No shield required
Able to communicate between Arduino and Raspberry Pi
Be able to run "point-to-multipoint"


user337: There is nothing that will work given those constraints.
You only have low power 5V signals on the Arduino which won't handle your distance requirements.
You could look into RS-485 using a shield on the arduino side and a breakout board on the Raspberry Pi.

1414: <p>I am looking for a multi-purpose wire protocol for Arduino.</p>

<p>Requirements:</p>

<ol>
<li>Range of at least 500ft (200m)</li>
<li>No shield required</li>
<li>Able to communicate between Arduino and Raspberry Pi</li>
<li>Be able to run "point-to-multipoint"</li>
</ol>
 337: <p>There is nothing that will work given those constraints.</p>

<p>You only have low power 5V signals on the Arduino which won't handle your distance requirements.</p>

<p>You could look into <a href="http://en.wikipedia.org/wiki/RS-485" rel="nofollow">RS-485</a> using a <a href="https://www.sparkfun.com/products/11959" rel="nofollow">shield</a> on the arduino side and a <a href="https://www.sparkfun.com/products/10124" rel="nofollow">breakout board</a> on the Raspberry Pi.</p>
