RE: [ha] My proposed system

Vermeulen Nic (
Tue, 27 Oct 1998 12:29:06 +0100


Some considerations that pop up after reading the ha post.
1. The idea of individual switches with some kind of autonomy is worth
to examine it's feasibility. The switch could talk directly to the lamp
(group of lamps) and vice versa. The main controller sees this messages
and plays the role of observer. Only for complex tasks and to program
the switches (switches must learn what they should do), the main
controller is needed.
However, this has several implications:
-the -controllers should have some EEPROM on board (to store the
address & parameters) and be no bigger than a wallplate (SMD?? I
soldered several SMD devices, not the fine pitch, and with a bit of
practice, this seems to be no problem).
-is it necessary to have a multi master protocol? I would say yes,
although this complicates the issue a bit. Maybe the CAN protocol can
help us to sort this out. CAN is multidrop, multimaster by bit
dominance, there's no physical layer defined and it has a very robust
error checking scheme. Disadvantages: small packet size and I never saw
an implementation in software?
-what if e.g. a light controller fails? I don't see any solution to
outguess this. I saw advertisements for systems that say they can deal
with that, but apparently, this is confidential info. I never got an
answer from any company.

2. If the system is really open, then the 1 wire devices from dallas
should get equal attention. (However I agree with Robin's comment and
100m/300m to wire a house isn't really that much).

3. If you post gerber files, can you re-import them and change the

4. Wire wrap is fine for prototypes, but I wouldn't try to put 230V on a
wrapped board!

5. My company has some 'not so professional' (protel) and professional
(cadence, veribest) PCB design tools here. The professional tools are
24h/24h occupied. I'm afraid we are stuck with the not so professional
tools. Though I haven't much experience with EMC compliant design, it's
a start.
>Question for Robin: I suppose you run Linux. What electronic design
tools do you use? I only know there is spice for Linux?

6. Many cooks make a bad kitchen, I know. But in view of the complexity,
I think we should try to attract more active members.

*The spelling mistakes expressed here are the author's opinion and do
not necessarily reflect the opinion of a dictionary*