Ohm Sweet Ohm: Outgoing Linux Australia president's hot-wired home

The man with an RFID tag implanted in his arm talks about controlling his world through software

Why have a key to open your front door when you can have an RFID tag implanted in your arm that will do the trick? Ever since he was a young boy, Jonathan Oxer has been fascinated by manipulating electronic devices to his mischievous ends.

Today, Oxer is technical director of a Web application development company called Internet Vision Technologies, and is the outgoing president of the Linux Australia community group. He has a young family that live in a seemingly normal home in suburban Melbourne.

However, Oxer's lifetime obsession with electronics has transformed his humble abode into what is possibly Australia's most hot-wired DIY home.

Just about every aspect of his home-life -- from checking the mail to watering the garden or opening blinds -- can be controlled through a software environment.

"When I was little we had a bungalow out the back and a good friend of my parents who was an electronics technician lived out there for a while. So from the age of about 5 or 6 I was always hanging around people that were into electronics," Oxer said.

"I've always been modifying things, never treating electronics as a sealed box but rather something that can be twisted to my devious ends."

One of the first modifications Oxer made was to link an irrigation system for his Melbourne property.

"I noticed the local hardware store was selling electronic timer taps for about $20...so I bought one, opened it up, had a look at the circuits and it turned out to be remarkably easy to modify."

He overrode the timer's circuits so that it could be turned on or off simply by sending it a signal from any source.

"The way I set it up was that if you shorted out two terminals that would put it in the on position, and if you unshort them it turns it off; it was very easy," Oxer said.

"Once I had it at that point it was a simple matter of connecting it to a relay that you control from a computer, and then you've got yourself an irrigation system that you can control from a software environment."

Once Oxer gained control of the device via software, he was able to implement numerous other inputs and processes to make the system more complex in order to adapt to Australia's harsh climate and water restrictions.

"If you have water restrictions that say only odd numbered houses can water on odd numbered days, then you could have a system with some logic that says: if the soil moisture is below a certain level; if I live in an odd numbered house; and it's an odd numbered day, if it's after a certain time of night -- because that's the only time I'm allowed to water -- and whatever other criteria you can think of, then it will go ahead and water."

Oxer said these sorts of decisions require only a couple of lines of code once the device is in the realm of software.

"By taking something simple and cheap, and modifying it so it can be software controlled, you can do all sorts of things with it you never previously imagined."

The front gate and letterbox of Oxer's home come complete with Ethernet connectivity, allowing him to be notified when somebody enters the property or when the postman delivers mail.

"It's such a pain walking to the letterbox to see if you've got mail!"

"I've setup a system that detects when a letter has been inserted into the letterbox, and that can be acted upon by a computer that can send me an SMS or an email to say that I've got mail. It doesn't really matter what it does - once you've got it in the realm of software you can control it."

To go even further - which Oxer admits having done just to prove a point - he can have the system trigger an event which sends an email into an object inside Second Life, which then creates a virtual representation of an email notification that there is physical mail to be collected - you've got mail to say that you've got mail.

Oxer is one of the few people in the world to have been surgically implanted with an RFID chip. When he swipes it past the RFID reader attached to his front door, the tag in his upper forearm unlocks the door.

"The door to my office also has a homemade RFID reader so I can unlock the door with a tag, but unfortunately this particular one doesn't work with the tag in my arm."

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Andrew Hendry

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