On Sun, 29 Jan 2012 19:28:00 -0800, you wrote:

>I'm making a set of light-up paving stones for a walkway, with PIC=20
>microcontrollers driving them, and a communications channel between=20
>them.  They'll only be a meter or so apart, and the cable buried in the=20
>ground (possibly in concrete).
>
>Rather than the expense of running RS-485 transceivers on each node,=20
>would it be practical to run a plain TTL level line from one to another,=20
>and do some kind of synchronous serial protocol over that?
>
>I'm trying to figure out if that would be dangerous corner-cutting or a=20
>wise avoidance of overengineering waste :)
>
>TIA,
>Steve
>
>--=20
>Steve Willoughby / steve@alchemy.com
>"A ship in harbor is safe, but that is not what ships are built for."
>PGP Fingerprint 4615 3CCE 0F29 AE6C 8FF4 CA01 73FE 997A 765D 696C

In a situation like this, where you don't have noise or long-distance issue=
s, probably your main
risk is problems caused by the shift in the level of the ground caused by t=
he power draw of the
lighting.=20

Another potential risk is damage caused by shorts from your supply during i=
nstallation - RS485
transceivers will typically take 12V without damage.

A 75176  RS485 transceiver is not exactly expensve =20

--=20
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