The immobilizer system consists of a passive transponder (for mutual recognition), mounted in the head car key, and antenna unit SMARTRA (SMARt TRansponder Antenna).
SMARTRA unit includes a built inductive antenna and circuitry connected to the ignition switch. SMARTRA unit is connected to the engine control unit a special link.
This method of control unit SMARTRA most expedient, as starting the engine controls the engine control unit.
The operating principle of the system
The immobilizer system includes an engine control unit and SMARTRA transponder built into the ignition key.
The engine control unit carries out the recognition of the ignition key with a special coding algorithm acting in parallel to the transponder and the engine control unit. Starting the engine is possible only with the agreement of the results of the algorithm steps. In the memory of the engine control unit stores the data of all transponders attached to the car.
The engine control unit and power SMARTRA communicate with each other using a special link. During the term of the relationship between the ECU and SMARTRA line "K" engine control unit for other types of communication can not be used, the engine control unit communicates through "K" or with the unit SMARTRA, or other devices (such as screening instrument for maintenance) by including a multiplexer and start the special procedures communications. Multiplexer - part of the hardware engine control unit. SMARTRA unit communicates via the transponder built into the ignition key. Communication is established at a radio frequency of 125 kHz. Block SMARTRA the ignition switch is placed on the frame near the transceiver radio antenna. The reception loop antenna RF signal is converted into a block SMARTRA
messages for serial communication, and received by the engine control unit converts the message to an RF signal transmitted via an antenna to the transponder.
Block SMARTRA does not make recognition of the transponder, or the calculation of the encryption algorithm. It is an improved interface which converts received radio frequency data stream from a transponder in a sequence of messages issued by the engine control unit, and vice versa.
Transponder - such as Hitag 2 with an improved encryption algorithm. When programming the transponder key to enter specific data of the vehicle, which recorded its
memory. The procedure for recording a one-time, so the contents of the memory of the transponder can not be changed. Data is entered as a chain length of 9 bytes composed factory. Content transponder memory is divided into two chains, which are called "identifier" and "password key."
After this programming the memory of the transponder is locked and its contents become impossible to read or change. The transponder goes from "pure" in the "Programmed" state.
Furthermore, each transponder is endowed with its own identification number IDE of 32 bits. Non IDE transponders unique (not repeated). Number IDE introduced at the factory and can only be read.
Key identifier and password are not transmitted from the engine control unit to the transponder, or vice versa. Transmits only the results of the action coding algorithm. As the result of the coding is almost impossible to calculate the specific data of the vehicle.
To encode the key or other purposes engine control unit is connected with a test device, as which can serve as a factory tester used at service stations Hyundai. Communication through the protocol line "K" ECU.