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tags:
all,
apache,
apachecon,
apacheweek,
bryce,
cve,
fedora,
fudcon,
geocaching,
gps,
ha,
jabber,
metrics,
microsoft,
nashville,
north carolina,
oscon,
red hat summit,
security,
trips
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mark :: blog
I'm fed up of keep missing the postman when he rings the doorbell and we don't hear it as we're in the kitchen or have the music on. It's one of those HA things I've never got around to - in my first student house 10 years ago the first thing we did was to hook the doorbell up to our shared-house Novell server (called Malawi since it lived inside a wood box with that label) so that it popped up on everyones computer when someone was at the door (and being students we'd just all just sit there and ignore it, perhaps sending popup messages to each other to find someone who would go answer it).
I use one of these RF doorbells (Friedland Libra) and picked up a identical spare unit from Ebay for 8 pounds. I made sure to get a battery one not one that plugs directly into the mains as they don't bother using a transformer to step down the voltage, so interfacing to it is more risky.
Inside is a RF circuit and a PIC microprocessor and, fortunately, one of the output pins acts as a mute for the sound circuit. So one pin is high around 3v and is pulled low for a couple of seconds as the doorbell rings). I hooked this to a 3-pin DS2406, a one-wire device from Maxim that can monitor a single IO pin (a high is 2.2v or greater) and report on the status (and if there have been any transitions since you last spoke to it). These things are mad, a tiny package the size of a transistor with internal processor, 1Kb of EEPROM and an unique id. Pretty reliable too, one has been monitoring the heating system for the last couple of years. So one device, four wires, and now a Jabber bot announces within about a second when there is someone at the door. All for about 10 pounds of parts and an hours work.
Created: 26 Aug 2004
Tagged as: doorbell, ha, jabber
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