Description

The SMART KEY system is a system that allows the user to access and operate the vehicle in a very convenient way. To access the vehicle, no traditional key or remote control is needed. The user carries a SMART KEY FOB, which does not require a conscious action by the user (such as pressing an RKE button). The SMART KEY system is triggered by pressing the button on the door handle. After triggering, the vehicle sends a request within a limited range. If the SMART KEY FOB receives this request, it automatically sends a response to the vehicle. The system then decides whether to perform a specific function (unlock, lock...) or remain inactive. Again, communication between the vehicle and the SMART KEY FOB is required before any function is performed. The system offers the following features:

• Passive Unlock via Driver and Passenger Door
• Passive Lock via Driver and Passenger Door
• Passive Start
• Passive Trunk Access via Trunk Lid Switch
• Passive Lock via Tailgate
• A maximum of 2 fobs can be processed by the system
• Immobilizer backup antenna driver is integrated into the SSB for TP authentication (i.e. keyless home mode).
• Communication with Engine Management System
• Communication with SRX
• LF-RF Communication

1. 1
   Passive Unlock The system allows the user to access (unlock) the vehicle without performing any action with the SMART KEY FOB. This function may differ depending on the platform as follows:

   A.	Pressing the Button on the Door Handle

2. 2
   Passive Lock The system allows the user to lock the vehicle by pressing the button on the door handle with the SMART KEY FOB.
3. 3
   Start Button. The system allows the user to switch power modes (OFF, ACC, IGN), as well as start and stop the vehicle engine, without performing any actions with the SMART KEY fob. Refer to Engine Start/Stop Button System Specification.
4. 4
   LIMP HOME Mode. In addition, the system provides a so-called "limp home mode," in which the user can operate all vehicle functions by inserting the key into the ignition key slot (ISK).

SMART KEY ECU (SMK ECU) The SMK ECU controls all functions related to "Passive Unlock," "Passive Lock," and "Passive Engine Start Enable." It reads inputs (door handle button, Start/Stop Button (SSB), PARK position switch), controls outputs (such as the exterior and interior antennas), and communicates via CAN as well as a single-wire interface with other devices in the vehicle. To communicate with the SMART KEY FOB, the SMK ECU generates a request (challenge) in the form of an encoded and modulated signal at 125 (or 134.2) kHz through the inductive antennas and receives the SMART KEY FOB's response through the external RF receiver. The main functional blocks of the SMK ECU are:

• Power Supply
• Flash Memory Microcontroller
• Single-Wire Interface to EMS
• Input Stage
• LF Antenna Amplifier/Driver
• CAN Communication with BCM

LF antenna amplifier/driver generates a sinusoidal 125 (or 134.2) kHz carrier signal, which is distributed to the different antennas. SMART KEY FOB The system supports up to 2 SMART KEY FOBs. Main functions of the SMART KEY FOB:

• Passive function: receives the LF call and automatically sends an RF response.
• Classic RKE function by means of up to 4 buttons.
• Transponder function in case of a discharged battery or disrupted communication.

Antennas

1. 1
   LF transmitting antennas: Inductive antennas in and on the vehicle are used to convert current, controlled by the SMK ECU antenna driver, into a 125 (or 134.2) kHz magnetic field, which is the carrier for the SMART KEY challenge. Three antennas cover the exterior of the vehicle: two antennas in the door handles (DS and PS) cover the area around the doors; one antenna in the rear bumper covers the area around the trunk or liftgate. Up to three antennas cover the vehicle interior and cargo area: two in the cabin and one in the trunk or cargo area.
2. 2
   Bidirectional immobilizer antenna (for Limp Home): The backup immobilizer antenna is used to send and receive data: it radiates a magnetic field (125 - 135 kHz challenge) and receives changes in field strength (transponder response).

Door handle The front door handles of both doors (driver/passenger) are equipped with LF transmitting antennas for sending 125 (or 134.2) kHz signals. The front door handles are also equipped with push buttons. Pressing the button on the door handle serves as a trigger to indicate the user's intention to unlock or lock the vehicle. The buttons are installed on the front doors, built into the door handle. Another button is installed on the liftgate or tailgate.