Intelligent car security anti-theft system circuit diagram

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A design scheme of a vehicle security anti-theft system based on radio frequency identification technology. In RF communication, the system uses a combination of the 434 MHz UHF band and the 125 kHz LF band to implement system tire pressure monitoring, remote door lock and engine immobilization. The debugging results show that the system improves the anti-theft and control of the car, saves system space, reduces production costs, and optimizes the body network.
RFID-based automotive security anti-theft system Radio Frequency Identification (RFID) is a non-contact automatic identification technology. The car security anti-theft system uses radio frequency identification technology to automatically identify the target object and obtain relevant data through the radio frequency signal. RFID technology uses RF transmission to read chip data through external materials for non-contact operation. Communication data uses an encryption algorithm to encrypt data for secure data storage, management, and communication. With the rapid development of electronic technology, the integration of electronic chips has increased, and the cost of RFID systems has been continuously reduced, accelerating the promotion and application of intelligence in the automotive electronics industry. The intelligent car security anti-theft system consists of a tire launch module, a remote key module and a base station module. For RFID systems, the size of the transceiver frequency determines the identification distance of the RFID system, the ease of circuit implementation, and the hardware design cost. In the car security anti-theft design, the low frequency (LF) band such as 125 kHz is used for the identification of automotive engine anti-theft systems with close-range, low-speed, and less data requirements; the UHF band such as 434 MHz is used for far Identification of distance radio frequency communication systems (automobile tire pressure monitoring systems and remote keyless entry systems).
The tire module circuit tire module consists of the tire state data acquisition and transmission circuit, as shown in Figure 2.

The tire module circuit uses FREESCALE's intelligent embedded sensor MPXY8300. This series of sensors integrates the company's low-power S08 core with 512 bytes of RAM and 16 KB of Flash, while also integrating low-power capacitive pressure and temperature. Sensor and single channel low frequency input interface. Its RF transmit supports both 315 MHz and 434 MHz carrier frequencies and can be programmed to enable amplitude shift keying (ASK) or frequency shift keying (FSK) modulation. It also integrates a charge pump function that increases the RF transmit section supply voltage when the battery voltage is low, allowing it to still achieve a certain RF emission intensity. The MPXY8300 is a system-on-chip (SOC) that integrates a pressure temperature sensor, 8-bit microcontroller (MCU), RF transmitter, and dual-axis (XY) accelerator into a single chip. MPXY8300 pressure measurement range: car 100~800 kPa, truck 100~1 400 kPa, temperature measurement range: -40~125 °C.
Key Module Circuit Key Module The PCF7961.PCF7961 from NXP is a low-power 8-bit MRKII architecture-based Reduced Instruction Set (RISC) processor that integrates a UHF transmitter with an LF transceiver. The chip can complete the RF transmitter and transponder low-frequency communication certification, and is suitable for the remote control anti-theft device of the motor vehicle. It uses a fast mutual authentication algorithm that uses random numbers, keys, and passwords with high sensitivity (long range) and short identification time (39 ms). The PCF7961 also provides a 32-digit identification number (ID) that has been cured at the factory. Figure 3 is a circuit diagram of the key module.

The base station module circuit base station module is mainly composed of a radio frequency receiving circuit, a low frequency transceiver circuit, a main control chip MCU, a LIN interface, and a human machine interface. The RF receiving circuit adopts the UHF RF receiving chip MC33596 of FREESCALE Company. After signal demodulation and data Manchester decoding, the data is transmitted to the base station main control chip MC9S08DZ60 for data processing (RKE data decryption) and instruction execution. The low-frequency transceiver uses the PJF7992.PJF7992 from NXP to integrate all the necessary functions to facilitate the reading and writing of the transponder. The base station microprocessor controls the communication between the PJF7992 and the transponder through the LIN serial interface of the PJF7992. The base station master chip uses the MC9S08DZ60 manufactured by F RE E SC ALE, which can configure and communicate the RF receiver chip MC33596 parameters through the SPI serial bus. The MC9S08DZ60 integrates two SCI (LIN) modules, which can control the low-frequency transceiver chip PJF7992 through one LIN bus. The other LIN bus realizes the transmission of commands to the engine electronic control unit (ECU) and the gate-related actuator. Add a LIN bus connection to the car security anti-theft system.