chrispeng [ad_1]
RFID (electronic tag, radio frequency identification) technology will penetrate into all aspects of our lives in the future. Its working principle is “the low frequency band is based on the transformer coupling model (energy transfer and signal transmission between the primary and secondary), and the space coupling model based on the radar detection target in the high frequency band (the radar emits electromagnetic wave signals that carry target information after hitting the target. Return to radar receiver). In 1948, Harry Stockman published “Communications Using Reflected Power” which laid the theoretical foundation for radio frequency identification technology. Today we are going to talk about how RFID technology can be used in car anti-theft systems.
γ
1. Overview of RFID car anti-theft system
At present, the anti-theft of automobile products can be divided into four categories: mechanical, electronic, chip and network. Although each has its own advantages and disadvantages, the development direction of automobile anti-theft is toward more intelligent chip and network. RFID car anti-theft system belongs to chip-type anti-theft system, which is a new application of RFID. Because this is a small enough radio frequency card that can be encapsulated in a car key and contains specific codewords. The system is equipped with a reader under the steering wheel of the car, and the distance between the reader and the ignition key is less than 7 cm. When a correct key with a transponder is inserted and hits the “M” position, the car anti-theft system is powered on and reads The device reads a valid UID number, the system voice prompts that the key is correct, and automatically completes the code matching and unlocks the engine computer. Otherwise, the engine computer is locked and the engine management system (EMS) locks the oil circuit and the engine, and the engine ignition and The fuel injection control is cut off, the car cannot be started, and the car’s central computer can easily prevent short-circuit ignition and realize the anti-theft function.
γ2. The composition principle of RFID car anti-theft system
The RFID system is the core component of the car anti-theft system. Generally, it is composed of three parts: an electronic tag (TAG, that is, a radio frequency card), a reader, and a radio frequency antenna. The tag is composed of a coupling element and a chip, and contains a built-in antenna for communication with the radio frequency antenna; the reader is used to read (write in the card reader) tag information; the radio frequency antenna is used between the tag and the reader Transmit radio frequency signals. The basic working process of the system is that the reader sends a certain frequency radio frequency signal through the radio frequency antenna; when the radio frequency card enters the working area of ββthe radio frequency antenna, an induced current is generated, the energy of the radio frequency card is activated, and then the radio frequency card encodes information such as itself through the card The antenna is sent out; the radio frequency antenna receives the carrier signal sent from the radio frequency card and transmits it to the reader via the regulator “target=_blank>, the reader demodulates and decodes the received signal, and then sends it to the background The main system performs related processing; the main system judges the legitimacy of the card according to logical operations, and makes corresponding processing and control for different settings, and sends out instruction signals to control the action of the actuator.
3. RFID car anti-theft system hardware design
This RFID automobile anti-theft system is composed of RFID system as the core. The hardware control unit of the automobile anti-theft system uses Motorola (Freescale) 16-bit microcontroller MC9S12D64. The radio frequency identification system consists of a reader S6700, a transponder TAG-IT and a radio frequency antenna. In addition, the system also includes storage circuit (AT24C01), detection circuit, voice circuit and CAN bus communication circuit.
The control unit MCU MC9S12D64 in this system continues the fine tradition of Freescale Semiconductor in the field of automotive microcontrollers. It is a member of the MC9S12 series microcontroller with the faster S12 core (StarCore) as the core. These two device pins Compatible, the memory can be upgraded. And there are a variety of peripheral devices to choose from. MC9S12D64 has 8 working modes. The setting of the mode can be realized by collecting the states of the three pins BKGD, MODB, and MODA during the reset period, which can enhance the selectivity of the application.
The S6700 IC card read-write multi-protocol transceiver and the transponder TAG-IT form a radio frequency system. The S6700 uses a 13.56MHz operating frequency. And has an anti-collision mechanism. As the S6700 uses Manchester encoding, it can allow multiple cards to read and write at the same time without conflict. The typical transmission power is 200mW. The protocols it supports include TITAG-IT protocol, ISO/IEC15693-2 protocol and ISO/IEC14443-2 protocol. The interface between the S6700 and the CPU is a synchronous serial interface (SPI). SCLOCK, DIND, and OUT are the clock line, data input line, and data output line respectively. The clock line is bidirectional. DOUT is used for data output during data reception, and it is used to indicate the internal FIFO register of the S6700 during data transmission.
The transponder TAG-IT is fully compatible with the ISO/IEC15693 protocol. There are 64-bit UID (card number), 8-bit AFI (application identification number), and 8-bit DSFID (data storage format) in the card. The UID cannot be modified. In addition, there is a 2KB EEPROM in the card, divided into 64 blocks, each block is 32Bit, and each block can be locked to protect the data from modification.
RFID technology is still in the development stage and will be closely connected with ours. As a professional RFID technology solution provider, Suzhou Xindao will be committed to promoting the popularization and development of RFID technology.
Article from: Suzhou RFID
[ad_2]
