Alberto Smulders wrote:

> Hello,
>
> For remote sensing and controlling in a greenhouse, we want to use
> bi-directional data transmission over power lines, using very cheap
> hardware (microcontroller eventually with incorporated ADC and
> relays/triacs for controlling stuff), so we can chatter around small "black
> boxes" in the greenhouse where we need them, without lots of dedicated
> wiring to a central controller; all the "black boxes" under control by a
> central PC running Win95 or (maybe) Win NT.

You are brave to use Win95 where there's more than 12VDC running around! Make
sure that a system hang-up does not electrocute your entire green house!

Perhaps you should still use external hardware to isolate your micro from the
AC. A friend of mine is building a "mains intercom" out of some mag. If you are
interested I'll find out which one. Perhaps/(lawfully) mail it to you.

> Generating FSK signals with the same microcontroller must be easy
> (frequency is low, around 100 kHz for power line data transmission).
> But is it possible also to use the microcontroller for filtering/decoding
> the signals, without using dedicated extra hardware?
> Any ideas - suggestions - critics - experiences - stories on frustrations
> (or not) - are welcome.
> Thanks....
>
> Albert A. Smulders
> InSAD - Encarnacion, Paraguay
> South America
> insad@itacom.com.py



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