Not to put too fine a point on it but this is early stage X-10.  I know I'm
going to hear about X-10 reliability on this one but if one follows simple
building set-up, it is ultra-reliable and bidirectional.  Off the shelf and
available in a jillion versions.

Rich

-----Original Message-----
From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu]On Behalf
Of Dario Greggio
Sent: Sunday, April 29, 2007 6:14 AM
To: Microcontroller discussion list - Public.
Subject: Re: [EE] RF mains switches


Tony Smith wrote:

> To be honest, I'd prefer infra-red.  For what I want to control, I'd like
to
> be there (not in the next room) so I can see what happens.

This is a point, indeed. Maybe a feedback from the receiver, confirming
that command was executed, could be as good.
I mean, I'd not use infrared since they can't pass walls :-)

> The adverts for these are a bit confusing.  I gather the remote sends 8
> codes, to control 4 devices, so 4 'ons' & 4 'offs'.  That's handy, having
> [...]

Yep, true

> I'm assuming these remotes are similar to the 433Mhz modules you can buy,
in
> that case you could modify them to add more functions.  As you say, just
> what is the protocol?  Might be like old RC cars that sent tones and
annoyed
> CB fans.

maybe. Or just a simple protocol.

> The last IR remote I made worked like that.  The remote generated a 'tone'
> on a 38k carrier, and an IR detector, tone decoder (NE567), flip-flop &
> relay made up the sensor.

Yes, this is the basic method, maybe from the '80s :-)

> I'm putting in a few ceiling fans (& exhaust), and I'm using "I couldn't
be
> bothered to run new wiring & switches" as my excuse for this.  For those
who
> saw the .au on my email and are thinking 'eh, you're six months late,
stupid
> Aussies, always behind", you be surprised at how well they warm up a house
> in winter.  And I'm not looking forward to the summer/winter switch
> discussion, even the mfgs get that wrong (or they've given up).

No, I did not notice it :-)
Ok, if you'll use it just for controlling the fan, then everything ok
with any of the above methods.


> Usually story, parts will cost me more than that.

Ok.
Then I'm not advicing you go ZigBee... :-)
If your needs are just those, then the switches you showed are pretty ok.

But, if you want to develop something with Pics and such, which actually
will cost *much* more as for prototypes but may cost about the same in
large scale, I'd tell you use a 18F PIC and a Nordic 2401 transceiver,
put there some bytes, and have something that can send as many commands
as you desire, read back status (even analog measurement), and have
multiple tx/multiple rx at the same time. And, of course, be interfaced
to a PC (maybe via USB).

--
Ciao, Dario
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