Simple home automation system
Last time I talked about my photoframe and room control setup. It was a laptop modification, and some hacking around in cheap remote controlled switches and simple scripts. I rebuilt most of the system now: a silent PC with normal screen serves the photos, it can control the lights and devices using a commercial product, there are cameras in the room and on the street, it’s all being shown and controlled by a slick webinterface, and my grandparents are quite happy with my old photoframe in their living room. :-)
Let’s get into details! The system is running on Aleutia T1, which is a really nice, silent PC-ish thing. PC-ish, because the performance is not really up to todays standards, but on the other hand it’s quite cheap, really silent and comes pre-installed with Ubuntu. Cool! (However, I installed Windows XP…) I got mine with a SSD, which means that there are no moving parts whatsoever, therefore it can stay on 24/7.
Using a simple XAMPP setup, it runs my photoframed software mentioned in the previous post (demo, source).
The webcam setup is quite interesting. First I tried to plug the webcams using some USB extension cords. It was highly unstable, so now the PC is actually positioned in a cardboard box, lifted from the ground, so all the cables fit exactly.
Another issue with the webcams is having it stream, but also have it stream securely. A promising format seemed to be MJPEG: this is just like sending out JPEG frames as fast as the connection can manage. I run the following code to generate a MJPEG stream using VLC. The stream is only accessible from localhost for security reasons.
vlc.exe dshow:// :dshow-vdev="USB Video Device" :dshow-adev=none :dshow-size=640x480 --no-sout-audio --sout=#transcode{vcodec=mjpg, vb=512, fps=1, width=640, height=480}:standard{access=http{mime="multipart/x-mixed-replace; boundary=7b3cc56e5f51db803f790dad720ed50a"}, mux=mpjpeg, dst=127.0.0.1:8080/cam.mjpg}
The boundary thing is a code required for modern browsers to correctly recognize the data type. If you remove the IP-address at the end, you’ll allow anyone to watch the stream. Now the next proxy is to make sure only authenticated people are able to see the stream. I tried this using a PHP script which simply read the stream and echo’ed it (and some other variants). I also tried using the Apache proxy module. But both options have the same problem: as I have a terrible internet connection, I really need the last frame. Once a frame is transmitted, the new frame must be the most recent frame possible. However, all options I tried seem to cache the data, so you’ll see 1 second of recording spread out on, like, half a minute on the client.
In the end I just went with a simple script I found online somewhere, that reads exactly one MJPEG frame and spits it out as ordinary JPEG:
$boundary="\n--";
$f = fopen($_GET['url'],"r") ;
if($f)
{
while (substr_count($r,"Content-Length") != 2) $r.=fread($f,512);
$start = strpos($r,'Ø');
$end = strpos($r,$boundary,$start)-1;
$frame = substr("$r",$start,$end - $start);
header("Content-type: image/jpeg");
echo $frame;
}
fclose($f);
Now you have to refresh the image using for example Javascript, so that’s fine too. The webinterface I’ve written for this purpose also features a slider to set refresh interval, which is pretty handy if you’ve got a shitty connection like myself. Also, this brings me to the home automation part, which is actually pretty brief. All devices in my room are plugged into a KlikAanKlikUit unit, and the PC’s got a TPC-200 interface plugged in, and a little bit of software does the trick (demo, source).
The TPC-200 interface comes with a DLL which has one single command: Send(id, value), with id being an integer and value a boolean. A simple executable wrapper, hacked together in VB, makes it easy to send commands from PHP, using exec.
The first room control breach has happened already: I used the inferior Apache Basic Authentication for the login procedure, and it turns out that sessions can keep open for a long period of time. Even when the server restarts during that time. I logged on the system on the laptop of a friend of mine, and 3 days later, he scared the crap out of me by playing with my lights. ;-) The PC restarts every night at 5am, so I’m still amazed that the session lasted that long.
Anyway, I quickly tracked him down using the access logs and we had a good laugh about it, but I still don’t trust the security anymore: the inside camera is pointed at the ceiling now… SSL and stuff like that will probably be secure enough, but if you’re considering building the same setup, don’t plug in your nuclear power plant.
Category: Hardware, Projects, Software, Web | One comment »
March 25th, 2010 at 01:38
Goedenavond, bijna ochtend,
heb met grote belangstelling gekeken naar je project met klik aan klik uit,
nou wil het volgende ik heb enkele module’s van klik aan klik uit echter wil ik graag heea via internet kunnen bedienen.
zowel intern als extern netwerk ik heb wel al heea geknutseld, maar wil nog wat uitbreiden.
wil dus nu graag mijn rolluiken via internet bedienbaar maken.
kun je mij vertellen wat dat zou kosten,
Hoor graag van je,
Met groet, Willem
ps, ik heb ook enkele beveiligings camera’s hangen maar weet niet of die te integreren zijn?