Continental MERCEDES BENZ RF Remote Control Transmitter User Manual
- June 2, 2024
- Continental
Table of Contents
Automotive
User manual / Functional description for
Continental – MERCEDES BENZ
RF – remote control transmitter
FBS 2b
315 MHz
General Radio Homologation Information
This device contains license-exempt transmitter(s)/receiver(s) that comply with Innovation, Science and Economic Development Canada’s license-exempt RSS(s) and complies with part 15 of the FCC Rules. Operation is subject to the following two conditions:
- This device may not cause harmful interference.
- This device must accept any interference received, including interference that may cause undesired operation of the device.
Changes or modifications made to this equipment not expressly approved by Continental Automotive Technologies GmbH may void the FCC authorization to operate this equipment.
The radiated output power of the device is far below the FCC and ISED radio frequency exposure limits. Nevertheless, the device should be used in such a manner that the potential for human contact during normal operation is minimized.
Functional description of the RF-transmitter
The transmitter is part of the Mercedes Benz access-control-system FBS2B. In general the following external functions are provided:
- LOCK of the car by RF or infrared (IR)
- UNLOCK of the car by RF or infrared (IR)
- remote control for rear opening hood (ROH)
- panic function (only the 4-button variant)
- comfort LOCK by infrared
- comfort UNLOCK by infrared
- battery protection control by optical red LED
- toggling of the default-unlock-function global- or selective unlock
Power supply
The transmitter is provided with 2 Lithium batteries (CR2025) which means a total power supply of +6V. The voltage of the batteries is checked with every triggered RF-telegram.
If this supply-voltage decrease under 3V (defined threshold), no more RF- telegrams will be transmitted. This low-voltage-detection is made by the components D2, R7 and the integrated A/Dconverter of the controller. A reverse-battery-protection is realized with D1.
Microcontroller
uPD754264 from NEC with AD-converter and EEPROM on chip. The clock for the controller is generated by a 2.6 MHz SMD-resonator.
Buttons
LOCK (S1):
used to send the LOCK-telegram and change the global/selective-unlock setting.
UNLOCK (S2):
used to send the UNLOCK-telegram and change the global/selective-unlock
setting.
Pressing a button turns the corresponding input-pin via an internal pull-up
resistor to ground.
ROH (S3):
by pressing this button more than 500msec, a IR- / RF-telegram will be sent
corresponding to the LOCK / UNLOCK function. The vehicle responds to unlock
the rear opening hood (ROH).
Panic (S4):
the Panic function is defined only for the USA variants (no IR). If the button
S4 (Panic) is pressed for at least 1 sec., the function is activated. This
timeout period was introduced in order to exclude faulty operations. The alarm
can be deactivated on the key only by a further short button press on PANIC.
Technical description of the RF-transmitter
Oscillator
The oscillator follows the colpitis oscillation principle stabilized by the
SAW. The frequency is fixed to 315 MHz ± 125 kHz.
The RF-transistor BFR92 is a SMD type. The transit-frequency is amount to 9 Ghz.
Parallel resonance circuit
The parallel resonance circuit (LC-circuit) is realized by the printed antenna
and the combination of C3 and C4.
Infrared transmitter
The infrared transmitter consists of a npn transistor (FMMT 491), a base input
resistor R9, a collector resistor R10 and an infrared transmitting diode D3
(SFH487-2).
Mechanical design
The mechanical design consists of two parts:
a) container
b) printed circuit board (PCB)
The battery-tank is integrated in the container between two metal-sheets on the PCP.
Transmitter modes
the key works in NORMAL-mode and runs with standard RF-telegrams. The user can determine if in NORMAL-mode by pressing any key for 1 sec to see a short blink of the red LED.
Entry:
First power-up-reset. After that press button LOCK or UNLOCK for a standard
RF-telegram.
Exit:
Press the button LOCK again
Electrical data
carrier frequency: 315 MHz ±125kHz
output power (carrier frequency): typ. -24 dBm
modulation: ASK
duration of telegram: 82 ms
transmission format: Manchester code
transmission rate: 1 kBaud
current consumption (active): typ. 5,5 mA
current consumption (stand by): < 1uA
operating remote-range: 10 – 15 m
power-supply: 2 Li-batteries (CR2025)
operation live: typical 2 years
operating temperature: -10°C …..+60°C
Variants USA / Canada
Part number
| Component| Type|
Variation description
---|---|---|---
5WK4 795| remote-control key with transponder | 315MHz|
4-button-RF-sender (with panic button)
5WK4 698
| remote-control key with transponder | 315MHz| technical variant: reduced
assembly 2-button-RF-sender
5WK4 7950A | remote-control key with transponder| 315MHz|
3-button-RF-sender
Block-diagram
- button 1 (LOCK)
- button 2 (UNLOCK)
- button 3 (ROH)
- button S4 (PANIC) 1)
- uPD75F4264
- A/D-converter
- EEPROM
- watchdog
- power supply
- LED
- IR-transmitter
- RF-transmitter
- colpitts oscillator
Legend for the figure above:
Button S1 (LOCK)
Button S2 (UNLOCK)
Button S3 (HDF)
Button S4 (PANIC)
A/D converter
Battery voltage
IR-transmitter stage
RF-transmitter stage
- only all USA variants
Mechanical Design
S1 LOCK
S2 UNLOCK
S3 HFE
S4 Panic
Company headquarters
Continental Automotive Technologies GmbH
Vahrenwalder Str. 9, 30165 Hanover, Germany
Register Court: Hanover
Commercial Register No. HRB 3669,
Tax ID: 25/200/00133 VAT-No. DE 341447066
Plant Regensburg
Siemensstrasse 12, Regensburg,
93055, Germany
Telefon +49 941 790 0
Telefax +49 941 790 4999
www.continental.com
Olaf Stranghöner
Technology, Manager Spare Parts
A SMY S2 PPM CC5 T