nice to see there is someone elso thinking of RS-485. I also found X-10 etc
too complicated as I have no problem with the cabling.
I've been developing my own home automation project for some time now. I
have working prototypes of two different microcontroller based devices.
The first I call "mains node". It is a small controller built around Atmel
89C2051 with 2kB flash. There's only a couple of circuits in it. It is
capable of controlling two separate 220V mains devices (external triacs,
power control in 64 steps), two external relays or LEDs and two
push-buttons. I plan to have several of these.
Software (like always..) requires a lot of work, but basic functions do
work. Coded in C, but I'll do it in assembler soon.
The other is more complicated board meant for control. It includes Intel
80C31, 32k EPROM, 8k EEPROM and 32k RAM, A/D and LCD interface onboard. I
have a small 10-key keypad in it also.
I have developed a BASIC interpreter for this to make it easy to program.
The BASIC code can be stored to the EEPROM and run automatically on
power-up.
Both devices communicate with RS-485. I've been keeping the speed down to
2400bps, as I don't need more.
The protocol is also my own, I call it "HomeNET". It uses fixed (7 bytes) or
variable length packets, and can connect to 253 nodes. Broadcast to all
nodes is also supported.
I'm also using a PC with the network, it has a simple RS-232 - RS-485
converter.
If anyone is interested, I can provide more info. Maybe I also add some
pictures to my web page some day...
Best regards,
Krister
Finland