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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 :: jabber
Last month I read a blog entry from
hadess via Fedora Planet about hardware to let you run homebrew
applications on Nintendo DS. There is a ton of homebrew applications
available, but as of yet no jabber client.
My home automation system is all based around XMPP, with a standard Jabber
server to which all the home automation systems connect to share messages. I
wrote it like this so that it would be easy to just take some existing Jabber
client for a platform and be able to come up with a nice looking front end with
minimal effort.
I found Iksemel, a portable
C XML parser and protocol library that looked perfect, and it only
took a couple of hours to have it ported on the NDS, and a couple
more hours to get it working with PAlib for wifi. It's not a generic
Jabber chat client, but it wouldn't take too much work to make it into
one (although I didn't bother with encryption support so you won't be
able to use it with Google talk servers for example). Anyway, the code
might save someone a few hours, so I've made the source available.
I've included a copy of Iksemel, so if you want to build this yourself
all you need is a working development environment: devkitpro and PAlib. This
still needs some work, I need to integrate a library to handle displaying
images from the network (when the phone rings it can pop up the callers
picture or a streaming picture from one of the cameras when the doorbell
is pushed)
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.
Back to work on Monday, but this holiday I've managed to avoid getting into doing real work by playing with the home automation system. I've now finished the conversion of all the components to Jabber bots, written a control client, and got all the one-wire Dallas switches and sensors up and running. some screenshots are available
A hope Google extends the shopping idea to the UK; I've wasted too many days this holiday looking for stuff for the house - just trying to find the right table for our kitchen took two days - I just want to search for a round glass 90-110cm table plus four chairs for under 400 pounds and click on 'buy me'.
So I've been spending some time trying to work out what to do with the home automation components - they're a mess of C and Perl that have no real way of communicating with each other. I found this thing called xAP which is designed for home automation components to talk to each other, but it's based mainly on UDP broadcast datagrams - not something I'd trust to make sure things happened when my alarm was triggered. Plus some of the components already written are under a non-GPL, non-BSD license that prohibits commercial use, yuk.
Anyway the idea was to look for something that would use standard components, where frameworks existed in Perl and C for me to write simple code, and to work on the principle of messaging - the UPS for example would respond to status requests and give you things like the temperature and voltage; with a heartbeat notification with the status included every minute; but with urgent alarms to anyone who registers an interest in getting them. Whats the solution? Jabber! In about an hour I had a jabber server running and a test Perl client doing just that; this thing will rock :)
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