The specific block diagram of the key end is shown in Figure 4. The main chip is the PCF7952 or PCF7953 of NXP, the RFF chip adopts the PCF7900 of NXP, and the corresponding RF receiving chip on the car side is the PQJ7910 of NXP. The PCF7952/53 has a low frequency analog front end (LF Front End) for connecting peripheral 3D antennas. In the keyless system, the key end needs an external 3D low frequency antenna, which can receive the 3D energy field strength of the external space, which are X, Y, and Z axes respectively. By superimposing the energy in three directions, the key can be guaranteed at any angle. The same field strength can be detected. One of the axis antennas is also multiplexed into the IMMO function to enable engine start in the no power mode. Through the uplink and downlink, the key and the car can establish two-way communication for complex identity authentication. The latest generation of authentication technology is called Mutual-Authentication. It requires not only the car to authenticate the key, but also the key to determine whether the car is legal. Any error will lead to the end of the entire communication, thus ensuring the security of the system. . The communication distance is determined by the low frequency uplink 125KHz. The effective working distance of the normal PKE system is about 2.5m, and the actual effective switching distance is 1.5m~2m. In addition to the detection accuracy inside and outside the car, the power consumption of the key end is also an important indicator to measure the quality of a keyless system. The power management module of the PCF7952 can reduce the power consumption of the whole system to the greatest extent. A mature keyless system solution and key With a 2032 3V lithium battery powered, the battery life can be as long as three years. This article refers to the address: http:// Since the solution involves communication technology, it also involves RFID, NFC (Near Field Communication) and GPS. By integrating the power of these technologies into a smart key, the smart key can communicate with you, the car, and even the world, and the results will be wonderful. Main communication technology concept In order not to let you stay in the suspense of some communication concept abbreviations, the following three brief introductions to the above three communication technologies: RFID - radio frequency identification. RFID is a smarter technology that emerges after the ubiquitous bar code. In addition to the transceiver, RFID also integrates some computer memory chips, so after receiving the inquiry signal, it does more than just indicate the ID number. GPS - Global Positioning System. Today, GPS has been used in high-end models, and drivers can determine the location of their vehicles on a map stored on a CD-ROM and displayed on the dashboard. GPS is also used in the automotive aftermarket. GPS receives signals from satellites orbiting the Earth and triangulates the location of your car. Commercial vehicle systems can be accurate to about 10 meters, and military systems are more accurate. NFC - short-range wireless communication. NFC is the latest of the three communication technologies discussed in this article. It is a close-range secure wireless technology that makes it easy to connect personal communications and portable devices. It is supported by large companies such as NXP Semiconductors and Sony. The standard. In November 2003, NFC has passed ISO/IEC (International Organization for Standardization / International Electrotechnical Commission) certification. NFC is a short-distance communication method with a working distance of only a few centimeters. By its very nature, the true value of NFC is optimized to provide intuitive, easy, and secure communication between devices without user configuration. Users only need to bring two devices close to each other to communicate. NFC has begun to be used in related devices such as Samsung and Nokia phones. Users can sign up for an exhibition or other event via an NFC mobile phone. This is an early application, but it is very representative and impressive. Users do not need to fill out the form, as long as the NFC-enabled mobile phone is shaken in front of the card reader, the required user information is instantly transmitted to the PC connected to the card reader, and the corresponding ticket is printed next to it. RFID application in automobiles The earliest application of RFID in automobiles was the anti-theft technology of automotive electronic engines from 1993 to 1994. The next important application for integrating RFID in cars is "keyless entry", which was conducted in 2003 under the leadership of NXP Semiconductors (then Philips Semiconductors). "Keyless entry" requires the driver to be near the car without having to remove the keychain or smart card from the pocket or wallet. The wake-up mode in the in-vehicle RFID transceiver can be activated by simply pulling the door handle of the driver's seat. At this point, the RFID transceiver scans the surrounding area to identify and locate the specific ID code of the RFID chip embedded in the key or smart card. Once found, the security algorithm determines if the chip is legitimate and decides whether to open the door. Convenience features start here. Once the owner's identity is confirmed, the system verifies that the key is in the car. If so, simply press the button on the dashboard to start the vehicle. Users can also store services, repairs, and customer records in a key or card through a combination of embedded computer memory and wireless communication, which is now available. Adding a transmitter to the repair shop's service desk makes it easy to transfer repairs, diagnostics, and mileage data. In fact, even if the car is moving away from the service station, some diagnostic data can be transmitted to the chip through the in-vehicle system. After entering the repair shop, the repairman can use this information to evaluate, and can also use this information to automatically order the parts used for repair. RFID can also be applied to other locations. Car parks and toll booths no longer need to pass another device, but seamlessly monitor the car's entry, exit and payment status with the key, and users can access and transmit content in new ways through the car infotainment system. Car search function The key will use GPS technology in the future to provide the so-called "looking for the car" function. The GPS coordinates of the car are automatically recorded in the key. However, understanding the location of the car in the form of north-south and east-west coordinates is not enough to find the vehicle, but also needs to know its own coordinates. Users can choose to integrate GPS chips in the keychain, or use the growing GPS in other popular mobile devices such as mobile phones and PDAs. In this area, NFC will bring better solutions. NFC, a very short communication technology, can connect all the information on a mobile phone or PDA to a key and further connect to the car itself. In the "Looking for a Car" solution, NFC will be used to send car coordinates to the PDA. A GPS-enabled PDA can recognize its own coordinates. The only thing missing is the map, and the map can also be stored on a PDA or mobile phone. It is also worth mentioning that the right-hand drive is a rented car, and the function of “looking for a car†is equally effective. First, it can effectively help users find rented cars on the rental company's parking lot. Once the driver enters the car, the address can be transferred from the PDA to the vehicle, eliminating the need for cumbersome keyboard input methods. If you are driving, it is not safe to do so. By integrating all of these features and information into a smart key or smart card, a new problem arises: What if the driver loses the key? The most obvious solution is the PIN code, but this is not convenient. Another method is to use biometric data to identify the owner of the key. The infrared light generated by the emitter in the keychain can be used in conjunction with the sensor to identify the peaks and valleys of the fingerprint. This infrared light also penetrates the skin and recognizes the hemoglobin characteristics of human blood. 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