Start • RFID Technology • High-Level Overview • Hardware • Software • Design Improvements • Sources and PDF

It all started when the antiquated push-code lock broke on our fraternity house’s front door. The mechanics of this primitive device limited the possible codes such that a pass code could have only four distinct numbers and the correct code could not be changed. With simple combinatorics, you can deduce that there were only 120 different combinations for possible codes. This meant even a moderately resourceful burglar could easily crack the code and steal our fraternity’s new 50" DLP TV.

At the time the lock failed, we were enrolled in Bruce Land’s ECE476 microcontroller design course at Cornell University. Only a week before, we had designed and tested a keypad security system built around an Atmel ATmega32 microcontroller, which was basically a modern version of the lock already on our door. However, this one had limitless four-digit pass codes, data logging, and administrative- overriding commands. Because we had to design and build a final project for the course anyway, we thought that developing a home security system to work with our student ID cards was a good idea.

The great thing about Cornell ID cards is that they have been equipped since 2003 with both magnetic stripe and radio frequency identification (RFID) capabilities. For our project, we chose the latter because we thought it would be a better blend of hardware and software design. And, basically everything from passports, to credit cards, to inventory tracking, has been adopting RFID technology. We figured it would be a little more cutting edge and relevant to modern topics of electrical engineering.