In the field of security technology prevention, the electronic password lock with anti-theft alarm function replaces the traditional mechanical password lock, which overcomes the shortcomings of mechanical password lock password and poor security performance, so that the password lock is technically and in performance. Greatly improve one step. With the development of large-scale integrated circuit technology, especially the advent of single-chip microcomputers, there has been a smart password lock with a microprocessor. In addition to the function of electronic password lock, it also introduces functions such as intelligent management and expert analysis system. Therefore, the password lock has high security and reliability, and the application is increasingly widespread. This paper introduces the intelligent password lock with 51 series single chip as the core, and elaborates its working principle, basic function block diagram, key design technology and software workflow.
1 basic principles and hardware components
The system of smart code locks consists of a smart monitor and an electronic lock. The two are placed off-site, and the smart monitor supplies the power required by the electronic lock and receives the alarm and status information it sends. Here, the line multiplexing technology is adopted to share a two-core cable for power supply and information transmission, which improves the reliability and safety of the system.
1.1 The basic principle and composition block diagram of the intelligent monitor
The block diagram of the intelligent monitor is shown in Figure 1. It consists of a single-chip microcomputer, clock, keyboard, LCD display, memory, demodulator, line multiplexing and monitoring, A/D conversion, buzzer and other units. Mainly complete the communication with the electronic lock, intelligent analysis and security monitoring of communication lines.
The intelligent monitor is always in the receiving state and receives the alarm information and status information from the electronic lock in a fixed format. For the alarm information, the sound and light alarms are immediately sent through the LCD display and the buzzer; for the status information, it is stored in the memory and compared with the historical state of the electronic lock before this time, and the trend is changed to predict the future. The status changes, and the corresponding information is provided to the duty officer through the LCD display for decision making. While the intelligent monitor establishes communication with the electronic lock, the A/D converter monitors the change of the supply current flowing through the communication line in real time, effectively preventing the damage caused by human factors and ensuring the smooth communication line.
1.2 Electronic lock basic principle and composition block diagram
The block diagram of the electronic lock is shown in Figure 2. It is also based on the 51 series MCU (AT89051) with the corresponding hardware circuit to complete the setting, storage, identification and display of the password, drive the electromagnetic actuator and detect its drive current. Value, receiving alarm signals from the sensor, sending data, etc.
The MCU receives the entered code and compares it with the password stored in the EEPROM. If the password is correct, the electromagnetic actuator is unlocked; if the password is incorrect, the operator is allowed to re-enter the password, up to three times; if three times If it is not correct, the MCU will alarm the intelligent monitor through the communication line. The single-chip microcomputer sends the unlocking operation and the driving current value of the electromagnetic actuator as the status information to the intelligent monitor at this time, and also sends the alarm information received from the sensor interface to the intelligent monitor as the basis of the intelligent analysis.
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