The electronic lock SmartCard4 is Security system project based on AVR AT90S2313, similar chip with ATtiny2313. Rudi Slejkovec uses Baskom AVR to compile the code. The advantage from this project is it has small physic, easy to make and use. It provides additional advantage to its safety since the connector of chip cards is set up on the external part of the door or the garage door, whereas the electronics is set up on the internal part. In this way a physical access to the electronics is not possible.
Documentation, source code and schematic