Design of car radio frequency identification anti-theft system based on ARM

　　1. Introduction

　　With the development of RFID technology, car anti-theft devices are becoming more and more rigorous, complete and easy to use, and the development direction of car anti-theft is towards chip-type and network-type with higher intelligence. The car anti-theft system based on radio frequency identification technology belongs to the chip-type anti-theft system, which is a new application of radio frequency technology. The car anti-theft system based on radio frequency identification technology has the characteristics of non-contact, large working distance, high progress, fast information collection and processing, and good environmental adaptability. This article focuses on the hardware design of an ARM-based radio frequency identification anti-theft system. On the basis of the hardware system, an embedded real-time operating system is transplanted to make the software design of the system more flexible. This system can well overcome the weaknesses of the battery remote control devices used on the market and effectively achieve the purpose of car anti-theft.

　　2. Anti-theft system principle

　　In the case of carrying the authorized "key" of the system, when the owner tries to enter the car, he only needs to pull the door handle, and the system will automatically unlock and let the user enter. At this time, the door will open automatically. This is because when the user opens the door handle or the trunk switch, it will trigger the sensor device in the car door, causing it to send a low-frequency signal containing password information to detect whether there is an authorized key within a certain range outside the car. This detection is usually within 1.5~2.0m of the key outside the car. When the "key" receives the detection signal, it will effectively send a high-frequency encrypted signal related to the key. The car will check after receiving the password signal. If the password is valid, the door lock of the door or trunk lid will automatically open. The whole process lasts very short and the owner will not feel it. When the owner enters the car and presses the engine start button, the system will start to detect whether there is an authorized key in the driver's driving position. If the authorized password is detected to be the same as the password stored in the system, the car engine will be started at this time. If forced entry is attempted, the system will not detect the authorized "key" and the car engine will not start even if the start button is pressed. The car is in a protected state at this time, thus achieving the purpose of car theft prevention.

　　3. Anti-theft system hardware design

　　3.1 Composition of Automobile Radio Frequency Anti-theft System

　　In this system, the microprocessor is the core component of the system, controlling the operation of other components. The radio frequency identification part is an important component of this system, which is responsible for reading the user's legal information.

　　The overall structure of the system is shown in Figure 1. S3C44B0X is the control center of the system, which controls the work of other modules. The radio frequency identification module completes the information reading of the authorized key. The GPRS module sends information to the owner through this module when the car is stolen. The voice module implements voice prompts to the owner. The car engine control ECU mainly controls the start and stop of the engine. The door and trunk control module is mainly responsible for the closing and opening of the door and trunk. The function of the JTAG module is to realize the debugging of the system. The main function of the sound and light alarm module is to realize the system alarm when the car is stolen.

　　3.2 Design of RFID System

　　The RFID system is an important component of the car anti-theft system, which consists of three parts: radio frequency card, reader, and radio frequency antenna. The tag consists of a coupling element and a chip, and contains a built-in antenna for communication with the radio frequency antenna; the reader can also write tag information in the reader-writer card, and the radio frequency antenna is used to transmit radio frequency signals between the tag and the reader.

　　The basic working process of the system is that the reader sends a radio frequency signal of a certain frequency through the radio frequency antenna; when the radio frequency card enters the working area of ​​the radio frequency antenna, an induction current is generated, the radio frequency card obtains energy and is activated, and then the radio frequency card sends its own coding and other information through the antenna inside the card; the radio frequency antenna receives the carrier signal sent from the radio frequency card, and after transmitting it to the reader through the regulator, the reader demodulates and decodes the received signal, and then sends it to the background main system for related processing; the main system determines the legitimacy of the card based on logical operations, and makes corresponding processing and control for different settings, and sends command signals to control the action of the actuator. The RI-R6C-001 radio frequency reader-writer chip is selected in this system. The transceiver (RI-R6C-001A) is combined with the MCU to fully implement the upper layer protocol for VICC operation specified in ISO/IEC15693-3. The physical layer protocol of VCD and VICC communication specified in ISO/IEC15693-2 is implemented by the internal ASIC of the transceiver. The communication interface between MCU and transceiver has three lines: SCLOCK, DIN, and DOUT, which represent the clock line, data input line, and data output line respectively. The hardware structure diagram of the system is shown in Figure 2.

　　4. System software design

　　4.1 Overall design of the system

　　The overall design of the system software includes the writing of the system startup code BOOTLOAD, the writing of the hardware driver, the porting of the embedded real-time operating system, etc. [4/5]. Since other papers have already made mature discussions, this article will not focus on it. [page]

　　4.2 Timing Commands for S6700 Series

　　The main software part of the card reader is to send the command sequence and receive the data to the S6700 series chip RI-R6C-001A through the MCU. The sending and receiving must comply with the internal ASIC communication protocol and ISO/IEC15693-3 specifications. Otherwise, no return information will be obtained.

　　First, the command issued by the software must meet the command format of the internal ASIC. The command structure of the internal ASIC is shown in Table 1.

　　in:

　　S1: is the start bit of the command sent by MCU to RI-R6C-001A:

　　CMD: Related commands supported by ASIC. When RI-R6C-0014A works in register mode, this bit is 1 byte. DATA: Specified by ISO/IEC15693-3, this part of data is generally sent to VICC. ESI: The end bit of the command sent by MCU to RI-R6C-001A.

　　4.3 Design of the card reading application program The design of the main program is to initialize each device before starting the card reading operation. The flow chart is shown in Figure 3:

　　5. Laboratory test verification

　　This system has been tested on the experimental system built by S3C44B0X. The system runs well, has a friendly operation interface, and has well realized the main functions of the system.

　　6. Summary

　　This article mainly introduces the design scheme of applying RFID technology to automobile anti-theft system. This scheme designs a hardware and partial circuit design of RFID system based on ARM. This article mainly introduces the method and implementation of applying this RFID technology to automobile anti-theft system. The new automobile anti-theft device developed by the author using RFID technology has not only stable performance, but also safe and reliable after several debugging and trials. It has also achieved good results in practical applications. Practice shows that this anti-theft device has the advantages of advanced technology, practicality, convenience, good compatibility, small size and full functions, and is a relatively ideal automobile anti-theft system.