My House Knows I'm Home
drbrain |
I bought a house last fall and upgraded it with Insteon switches (from MacHomeStore). I run Indigo on a Mac Mini to automate them all.
I wanted my house to know if it was or wasn't occupied so it could "do stuff" like turning off lights that were accidentally left on.
My girlfriend and I both have iPhones and while I could use the Find My iPhone feature, it isn't really accurate enough to know if I'm home and would probably drain the battery pretty quick if queried every five minutes.
I'm not sure if looking for the iPhones via ping or arp would work either, I've read the iPhone will shut off the WiFi adapter when it's not in use unless it's polling mail updates.
The iPhone has Bluetooth and it can be left on all the time without much battery loss. There's a handful of OS X apps that can execute a script when a bluetooth device comes in range but they only work for one device. Since my girlfriend also lives with me they won't work.
One of my coworkers got me to help him make a seemingly-abandoned Ruby Bluetooth library work on OS X using IOBluetooth.
The OS X side of the Bluetooth library started out with just the ability to scan for devices but I added remote name request, pairing, connection creation and signal strength.
It turns out that it's easy to see if a device is around once you have its address by asking for its name. There's no need to pair the device or create a connection (which will drain the battery faster).
Pairing and signal strength were implemented for the fun of walking around the house with the iPhone running a terminal session that monitored the signal strength and to see how well the Bluetooth signal works through my walls and floors.
Now that I could tell if the phones were nearby I needed to update Indigo with an occupied status. Indigo can monitor the occupied status and do something when it changes. The server is scriptable using AppleScript, so I used rubyosa to update Indigo with the presence of the phones. (The released rubyosa doesn't work on OS X 10.6, so I installed this version instead.)
All I needed now was the ability to run the script on a regular basis. I used Lingon to create a launchd agent that would run the script every five minutes. I told Indigo to turn off my interior lights when the house is no longer occupied, so if I leave the house (or turn the phones off) the lights automatically turn off.
I may also be able to do something more fancy like increase the poll interval once the house goes unoccupied to help it detect when I arrive home and do something like turn on the fireplace if it's cold, or turn on the entryway lights if it's dark.
Since I'm using Bluetooth my tools will work with any phone that can leave its radio on all the time. The phone doesn't need to be discoverable.
Hopefully I'll be able to release the Ruby Bluetooth library soon. I haven't been able to contact the original author and I'm not sure what the license is. I've replaced nearly all of the OS X portion of the library, but there's also extensive code for Linux and Windows.
Hopefully I'll also be able to convince Laurent to release an updated rubyosa that will work on OS X 10.6. comment
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