27 Jan 97, Craig Houston writes to All:

 P> I was wondering if anyone out there had any information on hooking up
 P> PICs in a network like structure.

 P> My plan is to have a bunch of PICs controlling various things, at
 P> different locations throughout the house, and wanted to link them all
 P> up - short of using a master PIC with all Tx / Rx lines from each PIC
 P> going into it, I thought a network topology would be best.

What speed is necessary for your application ? For low-speed technology
(till 1200 baud) we made one interesting solution:

All local controllers connected via 2-wire line and powered from the same
wires. Controllers number depends from their supply current and
in most cases could be in range 50...500. Total wire length could be up to
one kilometer (about 100 baud in this case). Total supply current for all
controllers should not exceed 300...800 mA.

System consist from one master controller and till 500 slave controllers.
Master controller power all slave controllers and transfer data to all
slave simultaneously by switching line polarity. Slave can transfer answer
to master requests by short-time line shortenings.

We install some working netwoks, based on this technology in various
applications: guard systems, home gas and water counters, sensor networks, etc.

I plan to made some kind of application note available in near future.

Alexey Vladimirov  avlad@mail.ormix.riga.lv

http://www.ormix.riga.lv/eng/mchip/mchip.htm
more than 300 PIC-related Net resources now...