Re: Room occupancy detection and door opening/closing - 1-wire or wireless solution?

["dermot_bradley" <bradley@xxxxxxxxxxxxxxxxxxxxx>]

--- In ukha_d@xxxxxxx, "Neil Wrightson" <neilw@...>
wrote:
>
> In the other building they are standard 12VDC security PIR's
> interfacing via 1wire.
> I use CAT5 too loop around the PIR's. 1 pair is the 0V, 1 pair is
the 12VDC,
> 1 wire is the 1 Wire Signal, the other wire of this pair is the
1Wire 0V.
> The remaining pair is for RS485.

So what do you use to interface the PIR contacts to 1-wire? Also what
about the power supply for the PIRs, how is that driven?

> In the building with 1Wire, the 1Wire is also used for lighting
> control.

Is this just some of 1-wire relay turning the circuits on and off?

> Depending on the room and time of day, the lights are turned on with
> movement detection and turned off after a predefined period.
> Say it is the middle of the day, movement in a particular room will
> turn on the lights for 5 minutes. If the PIR detects movement again
> after three minutes from the first detection the 5 minute timer is
> reloaded again.

That's basically what I have in mind.

What delay do you see with 1-wire based sensors, when someone enters
the room and triggers the PIR how soon before the lights come on?

I remembered that Hobby Boards did a small 1-wire PIR device but
couldn't see it on their www site. I emailed then and they indicated
its temporarily not available due to current exchange rates making the
sensors too expensive. From memory it was completely self-contained
(so must have been powered off the 1-wire 5V wire). What a pity
they're not available...



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