Secure Digital Access System Using iButton

The iButton is used here as a key to the access control system. Its unique identification (ID) number is used for authorisation. On detection of an authorised iButton, the system allows acces. The iButton is used here as a key to the access control system. Its unique identification (ID) number is used for authorisation. On detection of an authorised iButton, the system allows access. Thereafter, an automated lock key locks the system again. The system is permanently halted after five repeated false attempts. A service control unit built around an AVR microcontroller is interfaced to the iButton with 1-wire protocol for authentication of user validation of data. Learning: Application of ATMega16 microcontroller. Application of PC817 optocoupler. Application of MAX232 RS-232 driver. Implementation of the Bridge rectifier circuit for AC to DC conversions. Use of transistors as signal amplifiers.