The working principle of RFID car anti-theft device

Along with a large number of applications of automobiles, the requirements for automobile anti-theft are getting higher and higher. RFID radio frequency identification technology is a wireless, non-contact automatic identification technology, which has been widely used in public transportation, Access Control, logistics, production automation and other fields. It can also be used in car anti-theft devices, which can effectively reach the The purpose of anti-theft.

The working principle of RFID car anti-theft device

The basic principle of the car anti-theft device is to combine the mechanical key of the car with the electronic tag, that is, put the small RFID tag directly into the key handle. When a key with the correct identification code is inserted into the ignition switch, the car can be used correctly. way to start. The device can provide an output signal to control the ignition system. Even if someone enters the interior of the car in a destructive way, the car cannot be started by configuring the key for theft.

A typical car anti-theft system consists of two parts: electronic tags and readers. The electronic tag is the carrier of information and should be placed on the object to be identified or carried by the individual; the reader can have the function of reading or reading and writing, depending on the performance of the electronic tag used in the system.

(1) Electronic label

The electronic tag is the carrier of data, which consists of a coil (antenna), a memory for storing relevant identification information, and a microelectronic chip.

(2) Reader

The reader is used to read the data of the electronic tag and transmit the data to the microprocessor.

(3) Microprocessor

The microprocessor is the control part, which is used to unlock the car anti-theft system.

The composition of the anti-theft device

The anti-theft device is mainly composed of a read-write circuit, a single-chip microcomputer, a voice alarm circuit, a power monitoring circuit, a storage interface circuit, an electronic ignition system of an automobile engine and a keyboard.

If the key in the electronic tag is correct, the single-chip microcomputer will send a correct signal to the electronic ignition system of the car, and the car can be started. At this time, the voice alarm circuit does not work; if someone illegally configures the key to start the car, the single-chip microcomputer will send a signal to the voice system. The voice system will immediately sound an alarm.

Hardware circuit design

When the RFID read/write module is used in the car anti-theft system, one side is responsible for transmitting energy and exchanging data to the electronic tag, and the other side is responsible for the data communication between the electronic tag and the single-chip microcomputer.

(1) Send channel

Amplify the power of the carrier signal; transmit operation commands and write data to the electronic tag.

(2) Receive channel

Receive the response and data sent by the electronic tag to the reader.

(3) Carrier generator

The crystal oscillator is used to generate the carrier signal of the required frequency, and the frequency stability of the carrier signal is guaranteed.

(4) Clock generation circuit

The various clocks required for the work are formed through the frequency divider.

(5) MCU

The microcontroller is the core of the reader's work, and completes the work of sending and receiving control, sending commands to electronic tags and writing data, reading and processing data, and communicating with high-level processing application systems.

(6) Antenna

Form a coupling cross-link with the electronic tag.

Software system design

Software system design includes card reading software design, card writing software design, voice alarm program design and serial communication program design, etc. After the data transmitted by the IC card is received by the antenna of the base station, it is processed by the RFID read-write module and then sent to the input port of the microprocessor through the Output pin of the base station. Here the base station only completes the work of signal reception and rectification, and the work of signal decoding is done by the microprocessor. The microprocessor needs to perform decoding operation by simulating timing according to the duration of the input signal at high level and low level.

RFID technology transmits specific identification information in a non-contact, non-visual and highly reliable manner, which can be well applied in car anti-theft, improving car anti-theft measures, and avoiding car theft.