Radio frequency identification technology is mainly a non-contact automatic identification technology. In the process of its application, it is necessary to use the radio frequency signal to acquire information on the target object based on the electromagnetic principle. Due to its wide application, it can be realized. Applications in different areas are therefore widely used in various environments. In radio frequency identification systems, the output data of the RF reader needs to be strictly in accordance with the Wieggand format, that is, the transmission of two data lines of 0 and 1 respectively.
The access control system based on single chip microcomputer and radio frequency identification technology is a radio frequency identification lock system based on single chip STC89C52 and IC radio frequency card design. It can be used in laboratories, computer rooms, office buildings, archive rooms, financial rooms and other places with high security requirements.
1, system designThe access control system consists of a client installed on the door and an authorized end that authorizes the writing of the new card. The client consists of a power module, a MCU minimum system, a serial communication module, a swipe module, a buzzer module, and an electromagnetic lock module, as shown in Figure 1. On the client side, when the user needs to open the door, the IC radio frequency card needs to be placed in the sensing area of ​​the card reader to read the information in the card. When the read information is verified successfully, the buzzer is “clickedâ€. At the same time, the door lock is opened, and the lock is re-locked after one second delay; if the information verification fails, the buzzer will emit four consecutive short beeps. The authorization end is used to write authorization information for each IC card. The entire system can work with a single card reader and is easy to operate.
Figure 1 hardware system module block diagram
2, system hardware design 2.1, power module circuit designThe function of the power module supplies power to the entire system. In the system, the card module needs to use the 3.3V power supply voltage, the electromagnetic lock module needs to use 12V voltage, and the minimum system part of the MCU needs to use 5V voltage. Therefore, the power supply module needs to provide 12V, 5V and 3.3V three. The module converts 12V to 5V and 5V to 3.3V through the LM7805 and AMS1117 chips. Figure 2 shows the circuit design of the system power module.
Figure 2 power module circuit
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