This discussion is really interesting!

I have been dreaming about intelligent nodes to do simple functionality =
in
my homer and/or office. The PIC and the AVR processors made it all =
possible.
TCP/IP would have been nice for nodes but complexity and extra circuit =
costs
raised the price for the nodes. A low node price is probably the most
important factor possibly after ease of installation.

My first attemt was to use a 485 and build a simple yet capable system =
with
them (http://eda.sourceforge.net/mumin/) One important thing for me was =
that
a node should indentify itself when it is installed in the network. =
Also it
should be able to draw some power from the wires. This is solved in
M.U.M.I.N. To keep it really simple all nodes are seen as a device with =
a
set of registers and the protocol is built around this. This is the =
same
abstraction level that is used for IC-circuits.

Today I can still see some use for M.U.M.I.N. nodes but low speed USB =
nodes
with the same IC abstraction model is more often the best choice. Also
Dallas 1-wire is a good choice for relays/switches and other very low =
priced
pieces. The 1-wire net fullfill all of my original desig goals. One bad
thing is that there is pretty hard to implement 1-wite in software. =
Anyone
tried it?

So for a smart House/Office solution one end up with several layers. =
TCP/IP
for room or complex control situations. 1-wire, USB, something like
M.U.M.I.M., LIN (http://www.lin-subbus.org/) for the Last Inch =
solutions.

The CAN people must have come to the same solution as they developed =
LIN as
there cheap control net for simple things in cars and other rigid
environments. This may be the path to take. It is perfect for the PIC =
and
the AVR controlers.

If the control situation can bear the cost use TCP/IP. Its rock stable =
and
nice to work with. If price is a concerne don't....

/Ake

=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
=C5ke Hedman, CC-Systems AB, Box 83, 822 22 ALFTA,Sweden=20
Phone: 46 271 19380 Direct: 46 271 19209 Celluar: 46 70 2314980
Company home: http://www.cc-systems.com
Personal home: http://www.eurosource.se/akhe
Projects: http://eda.sf.net  http://mumin.sf.net

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