Secured room access system (ATMEGA8535 BASED DOOR LOCK)

Description

Abstract:

Security is a prime concern in our day-to-day life. And access control system forms a vital link in a security chain. The microcontroller-based digital lock presented here is an access control system that allows only authorised persons to access a restricted area. When someone tries to enter the restricted area by entering invalid passwords continuously, the system locks itself and can be unlocked only by the master user. The system comprises a small electronic unit with a numeric keypad, which is fixed outside the entry door to control a solenoid-operated lock.When an authorised person enters a predetermined number (password) via the keypad, the relay energises for a limited time to unlock the solenoidoperated lock, so door can be pushed/ pulled open. At the end of the preset delay, the relay de-energises and the door gets locked again. A prompt message is displayed on the LCD module. The system uses a compact circuitry

built around AVR microcontroller ATmega8535. The ATmega8535 is a low-power CMOS 8-bit microcontroller based on the AVR-enhanced RISC architecture. It provides the following features: 8 kB of in-system programmable Flash memory with read-while-write capabilities, 512-byte EEPROM, 512-byte SRAM, 32 general purpose I/O lines, 32 general-purpose working registers, three flexible timer/ counters with compare modes, and internal and external interrupts. The built-in power-on-reset circuitry of the microcontroller eliminates the need for external power-on-reset circuit. Switch is used to reset the system, which is accessible only to the master user. Port D (PD0 through PD7) is interfaced with the numeric keypad. Port C is interfaced with a 16-x2-line LCD. Four pins (PC4 through PC7) of
Port C are used as data lines for the LCD module and three lines (PC0 through PC2) are used for controlling
the LCD. Pin 40 (PAO) of port A is connected to the relay driver circuit