Car key development and radio frequency recognition technology


With the continuous development of technology, the shape and function of the car keys are also changing. The car key roughly experienced the mechanical key-the mechanical key of the integrated forwarder-folding key (the remote control key+mechanical key) -Smark key-Bluetooth key-NFC key several stages, the more convenient and the safety direction of the vehicle also obtained huge hugeness Improvement

1. RF recognition technology (RFID)

RF recognition technology is the key to intelligent and convenient car keys.

RF: The electromagnetic wave frequency that can be transmitted in space.


Electromagnetic waves below 100kHz will be absorbed by the surface and cannot form effective transmission. Once the electromagnetic wave frequency is higher than 100kHz, the electromagnetic wave can be spread in the air, and the ionization layer reflection of the ionizer of the atmosphere forms long -distance transmission capacity. This kind of transmission capacity. High -frequency electromagnetic waves with long -distance transmission capacity are called radio frequency, English abbreviation: RF.

RF signal: electromagnetic waves with a certain frequency of modulated

Basic composition of the radio frequency recognition system:

1. Electronic tag tag (ie, radio frequency card, responseer): Coupling element and chip composition, label contains built -in antennas to communicate between the radio frequency antenna; each label has a unique electronic encoding (ID).

2. Reader: Read (read card) label information device;


3. Aperts: Transmit radio frequency signals between labels and readers for data exchange.

The controller, computers, control units, modules, and control modules mentioned below refer to vehicle computers.

2. Mechanical key

The initial car key was a simple mechanical key, and it did not have the engine anti -theft function. Therefore, the anti -theft of the vehicle was very low. Once the door was opened, the vehicle could be driven away.


Mechanical key

Third, mechanical key with a transformer -engine anti -theft (IMMO)

Composition structure: forwarder (installed in the key, no power supply), IMMO anti -theft controller, EMS engine control unit, coil (generally located at the keyhole, the operating frequency is 125kHz, which is used to supply power and send signals to the forwarder).

The initial IMMO has an independent IMMO anti -theft control module. The current mainstream is the integrated IMMO anti -theft solution. The IMMO control module has also been integrated to other controllers (such as PEPS, BCM). The integrated formula is lower than the independent cost, the safety of security, the safety higher. Here we mainly introduce independent IMMOs to help us understand the principle of IMMO. The forwarder does not contain the power supply. For the normal matching key, when the current on the ON wires on the vehicle, the current can generate an electromagnetic field. At the same time, the anti -theft controller sends a signal to the key forwarder. To the anti -theft controller, the power signal (power supply) and clock signal (authentication time limit) and a set of random numbers are sent to the anti -theft controller. Certification of the anti -theft controller IMMO and the engine computers conduct wired communication certification. The two -step authentication is successfully allowed to start the engine at the specified time.

Fourth, remote control key RKE

The remote control key system includes the remote control key and the body controller BCM. The remote control key is divided into three parts: keys, microprocessors, and RF high -frequency transmitters. After pressing the button to wake up the microcontroller, the microcontroller sends the data stream to the RF transmitter of the key, and the carrier is transmitted to the air through the high frequency oscillating signal after the carrier. The receiving part includes RF high -frequency receiver and microprocessor. The RF high -frequency receiver receives the key to send a signal, passed to the processor for decryption, and forwards it to the corresponding controller to perform the operation and block lock.

The remote control key can integrate the IMMO engine anti -theft function to ensure the safety of the vehicle. However, there is a loophole in the REK system itself. The opening and closing of the door belongs to one -way authentication. The method of password copy and the same frequency interference can crack the anti -theft system.

5. Smart key pke

The system developed on the basis of human RKE, adding low -frequency authentication to two -way communication with different frequencies. It also has the function of remote control keys.

The PKE system mainly involves the mutual information certification between smart keys, PEPS controller, engine computer EMS, gearbox computer TCU (or steering column lock ESCL), and body control module (BCM).


Implementation of the keyless entry function: The driver carry the smart key to press the door handle handlebage or pull the door handle (the trigger method of different models may be different) to generate the trigger signal and transmit it to the PEPS controller. PEPS is triggered to drive the low -frequency antenna search available available. The key is sent with a low -frequency signal (including the awakening data of the key, and the communication data with the key). After the key receives the low -frequency signal, it is encrypted and emitted through the high -frequency transmission antenna. The encrypted data is compared.

At the same time, the PEPS system also uses the sensitivity of the distance between the low -frequency signal to the distance of the car key. The key can be used to measure the intensity of the low -frequency signal and feedback to the controller to achieve the accurate positioning of the smart key to confirm that the key is inside the car or outside the car.


Implementation of keyless startup function: After entering the vehicle, the vehicle is in a P gear. After the automatic vehicle is stepped on the brakes, the PEPS controller will be triggered to search the key through the low -frequency antenna. Send to the PEPS controller for verification, and the verification pass the start button to give the corresponding feedback. At this time, press the start button PEPS to conduct wired authentication with the engine computer EMS, and the engine can start the engine.

The smart key also contains the IMMO function. When the battery power of the smart key is exhausted, it is impossible to drive the RF module on the key to send a high -frequency signal to the outside world.

Some remote control keys and smart keys will also retain the mechanical key for emergency opening doors.

Smart key+mechanical key

6. Bluetooth key

The Bluetooth key is implemented using mobile devices (mobile phones). The entire system includes Bluetooth door locks, mobile devices, and background management systems. The Bluetooth door lock end is a data transceiver, which is also connected to the CAN network to realize the interaction with other controllers. The mobile terminal application selects the key that the user wants to pass, sends the data encryption and sends it to the specified IP server, and requests the background management system to implement the key transfer.

The Bluetooth module in the Bluetooth door lock receives data from mobile terminal applications, decrypts the main control module sent to the Bluetooth door lock, the main control module is transformed and sent to the CAN collaterals on the data. operate.

Bluetooth communication technology is very strong.


Seven, NFC key

NFC is close -to -field communication, close -range wireless communication technology developed from RFID and interconnected technology. Integrated sensors, inductive cards, and point -to -point communication functions on a single chip, the corresponding NFC also has three working modes: card reader, card analog, and point -to -point communication. NFC uses a special signal attenuation technology. The transmission distance is generally less than 10cm. The point -to -point communication security is high and the energy consumption is low;

NFC key

NFC card key

The current application of smart keys has basically popularized, and the application of digital keys is gradually occupying the market.