Smart Key System

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.
In a similar manner the vehicle's Electrical Steering Column Lock (ESCL) is released. 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 :
- Passive unlock via door driver side and passenger side
- Passive Locking Via Door Driver Side And Passenger Side
- Passive Start
- Passive access trunk via the trunk lid switch at the trunk
- Passive locking via trunk lid switch
- Max. 2 fobs can be handled by the system
- Immobilizer backup antenna driver integrated into FOB-HOLDER for TP authentication (i.e. limp home mode)
- Communication with engine management system
- Communication with SRX
- LF-RF communication

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:
A. Pressing Push button in door handle
2. Passive locking
The system allows the user to lock the vehicle by pushing a button on door handle with the SMART KEY FOB.
3. Button start
The system allows the user to release ESCL and 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.
4. LIMP HOME Mode
Additionally, the system offers so called "limp home mode", which is the user can operate all vehicle functions by inserting the key into the FOB HOLDER.

Smart Key ECU (IPM)
The SMK ECU manages all functions related to "Passive Unlock", "Passive Lock" and "Passive Authorization for Engine Start Operation".
It reads the inputs (Capacitive sensor / Lock button), 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.
For communication with the SMART KEY FOB, IPM (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 IPM are:
- Microcontroller with FLASH Memory
- Low speed CAN communication interface
- Single Line Interface to SRX
- Single Line Interface to ESCL
- Single Line Interface to EMS
- Input stage
- LF antenna amplifier/driver
The LF antenna amplifier/driver generates a 125 kHz sinusoidal carrier signal which is distributed to the different antennas.
The LF antenna driver consists of a number of outputs with different switching features, for passive access is used:
- Switch on/off Left side door handle antennae, front and rear
- Switch on/off Right side door handle antennae, front and rear
- Switch on/off bumper antenna for access to the trunk
- Switch on/off interior antenna
- Switch on/off hat shelf antenna
- Switch on/off trunk antenna

Smart Key FOB
The system supports up to 2 SMART KEY FOBs.
The main functions of the SMART KEY FOB are:
- Passive functionality: receives LF-challenge and sends automatically RF response.
- Classic RKE function by action up to 6 push buttons.
- Additional Mechanical key blade in case of a flat battery or a disturbed communication.
- LED for operation feedback and battery monitoring.

NOTE:
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.

Antennas
1. Emitting LF Antennas:
Inductive antennas in and at the vehicle are used to transform the current, driven by the PIC antenna driver, into a 125 kHz magnetic field, which is the carrier for the PIC challenge.
Five antennas cover the vehicle's exterior: Four antennas in the Door Handles cover the area around the doors; one antenna in the rear bumper covers the area around the trunk.
Five antennas cover the vehicles's interior and trunk interior: two in the passenger compartment, two at the hat shalf and one in the trunk.

External Receiver
The SMART KEY FOB's response is received via the external RF receiver, which is connected to the IPM via a serial communication Line.
The IPM provides a connector pin for the serial communication Line.

Door Handle
The front door handles of the four doors (driver door/passenger side of front and rear) are equipped with emitting LF-antennas to emit the 125 kHz signals. All door handles are also equipped with a capacitive sensor and a lock button.

Capacitive Sensor / Lock Button
The capacitive sensor as well as the lock button serves as a trigger to indicate the user's intent to unlock or lock the vehicle. Both switching elements are installed at every door, integrated into the door handles. Another button is installed at the trunk lid, integrated into the trunk lid handle.
After every reset of the IPM �C, signals from the capacitive sensors must be ignored by the IPM for 1 sec.

Operation

Passive Functions
The system allows the user to access the vehicle without having to perform any actions (e.g. RKE button pressing) with the SMART KEY FOB. It is sufficient that a valid SMART KEY FOB is located within a defined and limited range with respect to the vehicle. So the system is capable of detecting and authenticating a SMART KEY FOB in the ranges as specified below.
Passive functions mean:
- Passive Access
- Passive Authentication
Operating Range
The SMART KEY FOB receives and interprets a challenge sent from the vehicle via the exterior antennas in a free space range of min. 0.7m measured around the exterior antennas which are integrated in the door handles; The trunk access range is also min. 0.7m measured from the antenna position.
Passive Access (Passive Entry)
The SMART KEY FOB receives and interprets a challenge sent from the vehicle via the exterior antennas in a free space range of min. 0.7m measured around the exterior antennas which are integrated in the door handles; refer to the below given picture
Approaching one of the door handles with the integrated capacitive sensor indicates the operator's intent to access the vehicle and thus triggers the system.
Subsequently, the IPM sends a LF-challenge to the PIC FOB via the corresponding exterior door handle antenna. The PIC FOB answers with a RF-response.
If the received response matches the expected answer, the IPM issues an "unlock" message to the door control modules via the CAN network.
The system is able to distinguish between a PIC FOB on the driver or passenger side.
Special case: If the door is locked, but the ATWS is not armed, the IPM sends a sequence of silent telegrams at the interior antennas (interior antenna and hat shelf antenna) to avoid an unlocking with a fob inside the vehicle.

Passive Locking (Exit)
Pressing the Lock Button indicates the operator's intent to lock the vehicle and thus triggers the system. Subsequently, IPM sends a sequence of silent telegrams via the interior antennas to avoid the locking command given by a fob inside the vehicle. Then IPM sends a LF-challenge to the FOB via the corresponding exterior door handle antennas (corresponding means: the LF telegram will be sent at all door handle antennas on the same side as the user action has been performed: left or right). The FOB answers with a RF-response. If the received response matches the expected answer, IPM issues an all door passive locking message via the CAN network.

Passive Open Trunk
Pressing the Trunk Lid Switch when trunk is closed indicates the operator's intent to open the trunk and thus triggers the system. Subsequently, the IPM sends a LF-challenge to the SMART KEY FOB via the exterior bumper antenna. The SMART KEY FOB answers with a RF-response. If the received response matches the expected answer, IPM sends a "trunk open" message via the CAN network and activates its trunk latch output.

Passive Trunk Warning
Whenever the trunk lid is closed, IPM uses a suitable search strategy to avoid trunk buzzer warning by a fob outside the vehicle. Then IPM searches for a SMART KEY FOB in the interior of the trunk. If a valid SMART KEY FOB is found in the trunk, the IPM activates trunk warning to inform the user that the trunk has been closed with a fob inside the trunk.

NOTE:
- A blind spot in the trunk similar to any RF disturbance may lead to no trunk warning. Due to the penetration of the bumper antenna into the trunk area the lid may open without an Identification Device outside.
- A blind spot in the trunk similar to any RF disturbance may lead to no trunk warning

Activation And Deactivation Of Fobs
If ATWS becomes ARM MODE, the Smart Key system performs an interior detection of fobs.
In the following cases any Smart FOB detected within the vehicle's passenger compartment will be declared as Invalid FOB by the IPM until the ATWS goes into DISARM MODE:
- When vehicle has been locked by (Passive or RKE), a valid fob which does not send the lock command is found inside the vehicle
- When vehicle has been locked by Auto-Lock (automatic lock of the vehicle 30 seconds after unlocking, without opening of any door; a valid fob which does not send the unlock command 30s before is detected inside the vehicle
In contrast, if fob sent the lock command is detected inside the vehicle then IPM enters the silent telegram mode. The silent telegram mode means, that the IPM will perform a searching with interior silent telegrams for the next passive unlocking.

Smart Key Reminder Warning 1
1. Preconditions:
All terminals OFF & any door open & no fob-in & any door knob status is not locked to be checked by IPM periodically every 100ms, as long as CAN/LIN active.
2. Event:
At least 1 door knob changed from unlock to lock.
3. IPM actions:
A. IF NO FOB-IN ACTIVE
IPM performs a search for the fobs in the interior and hat shalf area of the vehicle.The same LF-strategy has to be used as it is defined for the ID out warning (registering only, no authentication / IPM perform a searching max. 2times if no fob has been found for 1st searching)
B. IF ANY FOB-IN ACTIVE
IPM sends unlocks command via CAN.

Smart Key Reminder Warning 2
1. Preconditions:
All terminals OFF & any door (including trunk) open & no FOB-IN & no locking status (checked by IPM periodically every 100ms, as long as CAN/LIN active)
2. Vehicle action:
Closing last door or trunk with knobs locked state, or with a locking in progress
3. IPM actions:
If all doors are locked within 500ms after closing the all doors, IPM performs a search for the fobs in the interior and hat shelf area of the vehicle; the same LF-strategy has to be used as it is defined for the ID out warning (registering only, no authentication).
A. Case 1: If no fob has been found, no action is required.
B. Case 2: If any fob has been found, IPM unlocks the vehicle and sends a request to the FAM for ext. buzzer warning.

Smart Key Door Lock Warning

Door Lock Warning 1
1. Preconditions:
ACC ON or IGN ON & No FOB-IN & All doors are closed.
2. Event:
A. User presses the lock button on door handle
3. IPM actions:
IPM performs a search for the fobs outside of the vehicle; the same LF-strategy has to be used as it is defined for Access door with ATWS disarmed.
If no fob has been found, no action is required.
If the preconditions are no longer valid during buzzer active time (3 seconds), the IPM stops the buzzer immediately.

Door Lock Warning 2
1. Preconditions:
All terminals OFF & any door open & no Fob-in
2. Event:
User presses lock button on door handle
3. IPM actions:
IPM performs a search for the fobs outside of the vehicle; the same LF-strategy has to be used as it is defined for all terminals OFF & any door open & no Fob-in
If no fob has been found, no action is required.
If the preconditions are no longer valid during buzzer active time (3 seconds), the IPM stops the buzzer immediately.

Door Lock Warning 3
1. Preconditions:
All terminals OFF & all doors closed & no Fob-in
2. User action:
A. User presses lock button on door handle
3. IPM actions:
A. If ATWS(Anti Theft Warning System) is in DISARM status, IPM performs a search for the fob inside of the vehicle (use "Door Lock Warning 3" scenario)
If no fob has been found, no action is required.
If the preconditions are no longer valid during buzzer active time (3 seconds), the IPM stops the buzzer immediately.

Smart Key Lamp Warning
1. IPM actions:
As long as the preconditions are valid, the IPM performs a periodical search for the fobs in the interior of the vehicle; the same LF-strategy has to be used as it is defined for the ID out warning (registering only, no authentication); periodical means, the search is done every 3 seconds.
If no fob has been found, the IPM starts Key out indicator lamp activation as all preconditions are valid and will perform another search 3 seconds later.
If any fob has been found, the IPM sends a Warning Off Command and will if one door is open perform an other search 3 seconds later; if no door is open then it's only at the next opening of one door if the condition are still valid that the search will be resumed.

Failsafe Functions (Backup For Limp Home)
In case of a discharged battery of the SMART KEY FOB or disturbed transmission, the following functions are available:
- Unlocking / locking of doors or trunk (or trunk depending of the vehicle configuration): use of mechanical key

User Information Functions
ID OUT Warning
1. Preconditions:
A. (ACC or IGN1) & (any door open or trunk open)
2. Event:
The last opened door is closed
3. IPM action:
IPM searches for a SMART KEY FOB in the interior including on the hat shelf.
A. If no valid SMART KEY FOB is found, the IPM activates interior buzzer and also sends ID OUT warning via CAN (exterior buzzer warning and internal buzzer warning).
B. If a door is opened and closed again during terminals on and inside valid fob, IPM stops interior buzzer and sends a warning off command on the CAN.

NOTE:
If there is a LF error (LF overheating or LF antenna failure), the system will have the same behavior as it is with no fob found.

Learning Description
In this chapter, the learning procedure for IPM, PDM, ESCL and FOBs is described.
For the learning of the IPM, PDM, ESCL and FOBs, it's necessary to have a connection to the diagnostic tool.

Learning MODE
Whatever the mode, the learning procedures are managed by the IPM.
Prior to start learning service, Fob-In signal must be active and the vehicle secret code (called as PIN code) should be known.

Teaching MODE
This mode is used by the dealers in order to replace IPM and/or PDM and/or ESCL and/or the set of keys, or to register additional keys for an existing system. That means the system already has been learnt with certain PIN Code. The PIN Code is fixed for the life time of the vehicle, therefore the same PIN Code must be used in this mode. Otherwise learning will be failed

Teaching MODE Procedure Description (Step By Step)
Objective: Key teaching procedure at service station
Initial state:
- IPM replacement: IPM is not learnt, PDM and ESCL and SMART FOB are already learnt with same PIN code
- PDM replacement: PDM is not learnt, IPM and ESCL and SMART FOB are already learnt with same PIN code
- ESCL replacement: ESCL is not learnt, IPM and PDM and SMART FOB are already learnt with same PIN code
- Additional or new keys teaching: IPM and PDM and ESCL are already learnt with same PIN code





Starting After Replacing (Virgin Start)
Starting is possible by following process after replacing new IPM , PDM, FOB key or ESCL.
- It is for starting at virgin condition
- All related parts are virgin condition (Smart key, IPM, PDM, ESCL ECM)
- ESCL is always unlock at virgin
- When virgin smart key is inserted in smart key holder, possible to start, IG ON and ACC position




- Press brake pedal in P or N range
- After inserting virgin smart key to holder, push start button once.