Re: Alarm panel linked to PC

[james@xxxxxxx (James Derrick)]

On Tue, 16 Feb 1999 10:40:23 +0000, you wrote:

>The question is - can anyone recommend an alarm control unit with a
>serial/parallel interface that is intended for domestic use (i.e. not
>costing more than 150). Any info on suppliers would also be
>appreciated.
I gave up trying and got a standard panel and after looking at the
input circuitry (an RC network feeding a PIC) added a 8bit CMOS
buffer/level shifter chip to feed the signals into a PC 8255 I/O card.


The alarm panel is remarkably simple, and uses a simple PWM serial
protocol to talk to its remote keypads. This interface could also be
tapped and monitored by the PC.

The alarm can give so much more than safe/ burglar/ fire. As it is fed
from room PIRs these can be used for occupancy monitoring to control
domestic lighting. When the panel is set, you are probably going out
or going to bed so this can be used to shift the heating to a lower
temperature.

This piggy-back approach has the advantage of leaving the standard
alarm panel unaltered, but needs 1 wire for each monitored zone
between the PC and the panel. It would be better to program a PIC to
act as an event monitor and get it to feed a serial line to the PC
controller.=20

One of these days I'll do this and add it to a RS485 multi-drop serial
network using something like the S.N.A.P. protocol. Other projects
include a LCD character display with a small keypad to act as a
controller.=20

I just need six months off work...

James
---
James Derrick    james@xxxxxxx, Cramlington, Near Newcastle, =
England
Forwarding Service: jderrick@xxxxxxx
Beyond the Horizon of the place we lived when we were =
young,
In a World of Magnets and Miracles. Pink Floyd.

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