Hyundai Elantra MD/UD: Description
The SMART KEY system is a system that allows the user to access and operate
a vehicle in a very convenient way. To access the vehicle, no traditional key
or remote control unit is needed.
The user carries a SMART KEY FOB which does not require any conscious
actions by the user (e.g. operate a RKE button). The SMART KEY system is triggered
by pressing a push button in the door handle.
After being triggered the vehicle sends out a request in a limited range.
If the SMART KEY FOB receives this request, it automatically sends a response
to the vehicle. Then the system decides whether to perform a particular action
(unlocking, locking…) or remain inactive.
Again, a communication between the vehicle and the SMART KEY FOB is needed
before any actions will be performed.
The System offers the following features :
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Passive unlock via door driver side and passenger side
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Passive locking via door driver side and passenger side
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Passive start
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Passive access trunk via the trunk lid switch at the trunk
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Passive locking via tailgate
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Max. 2 fobs can be handled by the system
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Immobilizer backup antenna driver integrated into SSB for TP authentication
(i.e. limp home mode)
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Communication with engine management system
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Communication with SRX
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LF-RF communication
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| 1. |
Passive unlock
The system allows the user to access (unlock) the vehicle without
performing any actions with the SMART KEY FOB. This feature could be
different depending on platform as follows:
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| 2. |
Passive locking
The system allows the user to lock the vehicle by pushing a button
on door handle with the SMART KEY FOB.
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| 3. |
Button start
The system allows to switch the power modes (Off, Accessory, Ignition),
as well as to start and stop the vehicle’s engine without performing
any actions with the SMART KEY FOB. See Button Engine Start system specification.
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| 4. |
LIMP HOME Mode
Additionally, the system offers so called “limp home mode”, which
is the user can operate all vehicle functions by pushing the key into
the SSB.
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Smart Key ECU (SMK ECU)
The SMK ECU manages all functions related to “Passive Unlock”, “Passive
Lock” and “Passive Authorization for Engine Start Operation”.
It reads the inputs (Push button in door handle, Start Stop Button (SSB),
PARK position Switch), controls the outputs (e.g. exterior and interior antennas),
and communicates via the CAN/LIN (depends on the vehicle) as well as a single
line interface to further devices of the car.
It reads the inputs (Push button in door handle, Start Stop Button (SSB),
PARK position Switch), controls the outputs (e.g. exterior and interior antennas),
and communicates via the CAN as well as a single line interface to further devices
of the car.
For communication with the SMART KEY FOB, SMK ECU generates a request
(challenge) as an encoded and modulated 125 kHz signal at the inductive antenna
outputs and receives the SMART KEY FOB’s response via the external RF receiver.
The main functional blocks of the SMK ECU are:
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Power supply
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Microcontroller with FLASH Memory
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Single Line Interface to SRX
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Single Line Interface to EMS
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Input stage
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LF antenna amplifier/driver
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CAN communication with BCM
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LIN communication with other unit (depending on platform)
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The LF antenna amplifier/driver generates a 125 kHz sinusoidal carrier
signal which is distributed to the different antennas.
Smart Key FOB
The system supports up to 2 SMART KEY FOBs.
The main functions of the SMART KEY FOB are:
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Passive functionality: receives LF-challenge and sends automatically
RF response.
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Classic RKE function by action up to 6 push buttons.
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Transponder-functionality in case of a flat battery or a disturbed
communication.
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LED for operation feedback and battery monitoring.
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The FOB's LED indicator may continue to light even with a low
transmitter battery.
If the performance or range of the FOB is less than expected,
check the transmitter battery.
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Antennas
| 1. |
Emitting LF Antennas:
Inductive antennas in and at the vehicle are used to transform
the current, driven by the SMK ECU antenna driver, into a 125 kHz magnetic
field, which is the carrier for the SMART KEY challenge.
Three antennas cover the vehicle’s exterior: 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.
Two antennas cover the vehicle’s exterior: two antennas in the
Door Handles (DS and PS) cover the area around the doors.
Up to three antennas cover the vehicle’s interior and the trunk
interior: two in the passenger compartment and one in the trunk.
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| 2. |
Bidirectional Immobilizer Antenna (for Limp Home):
The Immobilizer Backup Antenna is used for sending and receiving
data: it emits a magnetic field (125 - 135 kHz challenge) and receives
changes in the field strength (response of Transponder).
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Door Handle
The front door handles of the two doors (driver door / passenger door)
are equipped with emitting LF-antennas to emit the 125 kHz signals. The front
door handles are also equipped with a push button.
Push Button
The push button in door handle serves as a trigger to indicate the user’s
intent to unlock or lock the vehicle.
The push buttons are installed at front doors, integrated into the door
handles.
Another button is installed at the trunk lid.
