Technoblogy posts a project which is a digital combination lock that only lets you activate a circuit if you know the 8-bit key. It demonstrates an application of Configurable Custom Logic, a feature included in the latest AVR DA-series chips from Microchip.

The latest AVR processors released by Microchip all include a new feature called Configurable Custom Logic, or CCL, and since their release I’ve been trying to think of compelling applications of this feature. It allows you to construct an arbitrary logic circuit that works independently of the processor. This project demonstrates one practical application, using the logic functions to construct an arbitrary logic expression.

The Combination Lock uses this configuration to allow you to set an 8-bit input, using a DIP switch, and only if you set the correct combination will the output go high and light the LED.

See more in the blog post here.