Development of a Keypad-Based Password Security and Access Control System Using a Microprocessor Training Kit

Keypad-controlled locks protect doors, cabinets and equipment in many low-cost applications. This paper presents the development of a keypad-based password security and access control system using a microprocessor training kit. The software scans a matrix keypad, compares the entered code with the stored password, operates a lock through a relay driver and blocks input for a time after repeated wrong attempts. Correctness and response of the system are evaluated by simulation and its security limitations are discussed. In simulation the password logic gave the correct decision in 2000 of 2000 trials and the keypad was blocked after three wrong codes, while the key error rate fell from 84.8 % to 0.00 % with software debouncing.