Technologist Rob Hemsley has documented a method of creating a different yet fascinating type of door lock control. By turning the metal door handle into a capacitive sensor, an Arduino board measures the pattern of 'taps' or 'knocks' made on the handle. If the pattern matches the numerical equivalent stored in the EEPROM, the door is unlocked using a servo. For example:
To reproduce this system yourself, head over to Rob's website here. And we're on twitter and Google+, so follow us for news and product updates as well.
To get started with your own embedded-Arduino and USB emulation projects - look no further than the Freetronics LeoStick. Apart from being one of the smallest Arduino-compatibles on the market with USB, it also has an onboard RGB LED and piezo for sound and it's own form of knock detection: