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

["Neil Wrightson" <neilw@xxxxxxxxxx>]

Hi,

Standard security PIR's run off 12VDC.
They also usually have a dry (Voltage free) set of contacts that close
indicating movement.
So, the 12VDC on the CAT runs the PIR's and the relay switch contacts go to
the 1Wire I/O device (DS2407).
This is mounted on a small PCB in the bottom of the PIR where the outside
cabling comes in.
They are usually a TO92 package, so I guess you could even do away with the
PCB.

Speed wise, there is approximately a 1 second delay from entering the room
to the lights turning ON.


Regards,

Neil Wrightson.


_____

From: ukha_d@xxxxxxx [mailto:ukha_d@xxxxxxx] On Behalf Of
dermot_bradley
Sent: Thursday, 16 October 2008 8:17 PM
To: ukha_d@xxxxxxx
Subject: [ukha_d] Re: Room occupancy detection and door opening/closing -
1-wire or wireless solution?



--- In ukha_d@yahoogroups. <mailto:ukha_d%40yahoogroups.com>
com, "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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