Immobiliser

Description of the system

The immobilizer system consists of a passive transponder (for mutual recognition), mounted in the head car key, and antenna unit ?�Smartra?� (Smart Transponder Antenna).

Block ?�Smartra?� includes built inductive antenna and circuitry connected to the ignition switch. Block ?�Smartra?� connected to the engine control unit a special link.

This method of control of the unit ?�Smartra?� is the most appropriate, since starting the engine controls the engine control unit.

The principle of operation of the engine control unit

The engine control unit performs recognition of the ignition key with a special coding algorithm acting in parallel to the transponder. Starting the engine is possible only with the agreement of the results of the algorithm steps. The engine control unit stores the data of all transponders attached to the car.

The engine control unit and the block ?�Smartra?� communicate with each other using a special link. The engine control unit communicates through either a block of K ?�Smartra?�, or with other devices (eg, a test device for maintenance) by including a multiplexer and run special procedures communications. The multiplexer is part of the hardware engine control unit. Block ?�Smartra?� communicates via the transponder built into the ignition key. Communication is carried out at a radio frequency of 125 kHz. Block ?�Smartra?� installed on the ignition switch next to the frame receiving and transmitting radio antenna. The reception loop antenna RF signal is converted to a block ?�Smartra?� in messages for serial communication, and received from the engine control unit converts the message to a radio frequency signal transmitted through the antenna on the transponder.

Block ?�Smartra?� does not produce identification transponder or calculation algorithm coding. 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 - type ?�Hitag2?� with advanced coding 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 in the form of a chain of 9 bytes compiled by the manufacturer. 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 can not be read or modified. The transponder goes from "pure" in the "Programmed" state.

Furthermore, each transponder has its own identification number IDE on 32 bits. Non IDE transponders are 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 a result of encoding the specific data to calculate the vehicle almost impossible.

To program a key or other purposes engine control unit is connected with a test device, as which can serve as a factory for maintenance tester used at service stations. Communication is carried out on the Protocol line to the control engine.