Siemens SVI-HMFNA04 User manual

SIEMENS Automotive systems Corp. SASCO
Page 1 of 5
Functional Description /
User Manual
SIEMENS Automotive Systems Corp.
Smart Key Fob
SVI-HMFNA04

SIEMENS Automotive systems Corp. SASCO
Page 2 of 5
FCC Compliance Statement.
This device complies with part 15 of the FCC Rules.
Operation is subject to the following two conditions :
(1) This device may not cause harmful interference, and
(2) This device must accept any interference received, including
interference
that may cause undesired operation.
Do Not.
Any changes or modifications to the equipment not expressly
approved by the party
responsible for compliance could void user’s authority to operate
the equipment.

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1. System configulation
1.1 Scope of SMART KEY SYSTEM
The System offers the following features:
•passive access for two doors, driver side and passenger side as well as trunk/tailgate
•passive start after interior detection of the SMART KEY FOB (without interior trunk and
hat shelf detection)
•LF-RF communication (based on Siemens’ SMART KEY system)
•passive access trunk/tailgate via the trunk lid switch at the trunk
•max. 2 SMART KEY FOBs can be handled by the system
•communication to the engine management system via a single line interface
•communication to the ESCL via a single line interface
1.2 Short description of the SYSTEM
1.2.1 General Definition of SMART KEY
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 itself does not require any conscious
actions by the user (e.g. operate a button).
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.
1.2.2 Wireless Communication
Electromagnetic waves are used to exchange information between the vehicle and the
SMART KEY FOB. Both, vehicle and SMART KEY FOB are equipped with a transmitter,
a receiver and several antennas.
1.2.3 Concept Description
With this concept it is possible to have a set of interior antennas that covers the vehicle’s
interior and a set of exterior antennas that covers the vehicle’s exterior.
For an unambiguous separation between the vehicle’s interior and exterior it is sufficient
that at least one area is covered exactly by the corresponding operating ranges of the
antennas.
The functions of the SMART KEY system have to be provided in a clearly defined and
limited range. For the up-link from the vehicle to the SMART KEY FOB, a magnetic field
with a frequency of 125 kHz and ASK modulation is used. Inductive antennas in and at
the vehicle radiate the electromagnetic energy.

. Proprietary data, company confidential. All rights reserved. Confié à titre de secret d'entreprise. Tous droits réservés. Comunicado como segredo empresarial. Reservados todos os direitos. Confidado como secreto industrial. Nos reservamos todos los derechos.
. Weitergabe sowie Vervielfältigung dieser Unterlage, Ver
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wertung und Mitteilung ihres Inhalts nicht gestattet, soweit nicht ausdrücklich zugestanden. Zuwiderhandlungen ver
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pflichten zu Schadenersatz. Alle Rechte vorbehalten, insbe- sondere für den Fall der Patenterteilung oder GM-Eintragung
Technical aspects of 125 kHz – magnetic field:
•virtually no reflections,
•cubical decrease of field strength →allows good range control,
•released frequency band (ISM),
•high penetration,
•low quiescent current demand due to 125 kHz input stage (SMART KEY FOB),
•less sensitive for detuning compared to higher frequency.
For the down-link from the SMART KEY FOB to the vehicle, the standard radio frequency
(RF) is used (similar to the classic remote control functions) with FSK modulation.
1.3 System Overview / Block Diagram
Figure 1: Principle of Communication
ECU sends LF challenge via exterior antenna
ID tag sends identification code to RF receiver
Doors are unlocked automatically
User pulls open the door
L
F

. Proprietary data, company confidential. All rights reserved. Confié à titre de secret d'entreprise. Tous droits réservés. Comunicado como segredo empresarial. Reservados todos os direitos. Confidado como secreto industrial. Nos reservamos todos los derechos.
. Weitergabe sowie Vervielfältigung dieser Unterlage, Ver
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wertung und Mitteilung ihres Inhalts nicht gestattet, soweit nicht ausdrücklich zugestanden. Zuwiderhandlungen ver
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Figure 2: System Block Diagram

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. Weitergabe sowie Vervielfältigung dieser Unterlage, Ver
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wertung und Mitteilung ihres Inhalts nicht gestattet, soweit nicht ausdrücklich zugestanden. Zuwiderhandlungen ver
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pflichten zu Schadenersatz. Alle Rechte vorbehalten, insbe- sondere für den Fall der Patenterteilung oder GM-Eintragung
2 Smart Key Fob for homologation
2.1 Button operation for homologation
1st time button pressing : Low side Frequency (Carrier wave continueous mode)
2nd time button pressing : High side Frequency (Carrier wave continueous mode)
3rd time button pressing : FSK Modulation (Modulated wave continueous mode)
4th time button pressing : Stop operation.