Is My Roommate Home?

By Joshua Berry on Day 2

Better late than never is my post about Day 2’s project! Sometimes you just want to be alone. If you’re already out and you knew your roommate would be in your apartment, you may decide to stay out. Likewise if you knew your roommate was gone, you might decide to stay in and relax while watching your shows. The solution is “Is My Roommate Home?” This device will *eventually* email, text, or call you with rommate status. Hardware issues prevented me from actually hooking this up to the Internet, but in the spirit of completing one project in one day, I’m happy with the progress. Main parts include a photocell, digital switch, and of course, and Arduino. See below for explanation.

A photocell (or ideally an IR sensor, which I could not obtain on short notice) attached to the ceiling inside your apartment, several feet from your front door, recognizes a change in light. This means that your roommate is inside your apartment and is either on his/her way out or his/her way in. The second piece is below.

This simple digital switch is made of scrap metal. One piece is attached to the door and the other to the threshold. When the door is closed the switch is on, and when the door is open the switch is off. If the photocell reading occurs before the switch opens, your roommate has left the apartment. If the switch opens before the photocell reading, your roommate has arrived. In each case you will be notified by either SMS/phone/email.

Here are photos of the breadboard and a bird’s eye view of the entire uninstalled device. The device is missing an XPort to connect this to the Internet. Luckily I have the code for this, so I plan to wrap this up next week after 5in5 is over.

August 1st, 2008