Head Unit, Component Description - GF82.85-P-3140FRB
Model 257, 290
up to model year 2021
with code 531 (COMAND APS)
Shown on model 257.3
Location
The head unit is located behind the instrument panel cover in the center console behind the upper control panel control unit (N72/1).
Tasks
The head unit has the following tasks:
- Central operating and display unit for the entertainment and communications systems integrated in the vehicle
- Integration of smartphones
- Evaluating and forwarding control signals
- Reading in of input signals as well as actuation of output media and system components
Central operating and display unit for the entertainment and communications systems integrated in the vehicle
The head unit provides the user with a structured and uniform user interface for the following system components:
- Audio (e.g. radio, Bluetooth® audio, SD card (Secure Digital), Universal Serial Bus (USB) including integrated Media Interface for connecting iPhones® or MTP devices (Media Transfer Protocol))
- Telephony
- Internet (including WLAN hotspot (Wireless Local Area Network))
- Voice control system (VCS [SBS])
- Navigation (with data from internal hard disk) including extended functions of navigation mode
- Digital operator's manual (interactive)
- Video, including TV (with CODE 865 (TV tuner))
The user interface is shown on the Audio/COMAND display (A40/8).
Using the "Vehicle functions" menu, equipment-dependent contents and functions of additional systems (e.g. climate control, seat adjustments) can be shown and controlled on the Audio/COMAND display.
Integration of smartphones
The head unit enables the integration of smartphones by supporting the following integration standards:
- CarPlay (Apple) (with code 16U (CarPlay smartphone integration))
- Android Auto (Google) (with code 17U (Google Automotive Link smartphone integration))
- CarLife (Baidu) (with code 18U (Baidu CarLife smartphone integration))
In order to be able to use smartphone applications, the smartphone must be connected to the front center console USB connector (X115/5) (with code 896 (Vehicle access and drive authorization through mobile phone), code 897 (Wireless mobile phone charging) or code 899 (Multifunction telephony)) or to USB connector 2 (A90/5x2) (except code 896 (Vehicle access and drive authorization through mobile phone), except code 897 (Wireless mobile phone charging) and except code 899 (Multifunction telephone)) and the integration standard selected through the "Connect" menu. If the "Automatic connection" setting has been selected, activation cannot take place via the menu. If a smartphone is connected and the integration standard Android Auto or CarPlay is activated, the head unit is switched to a special operating mode ("Integration mode") in which not all head unit functions can be used. The following functions of the head unit are not available if Android Auto or CarPlay is activated:
- Media player
- Navigation
- Voice control system
- Telephony (with CarPlay)
The radio (AM and FM) functions, vehicle settings and safety-relevant functions such as, e.g. emergency call system (with code 362 (HERMES LTE)), can still be used in any case.
With Android Auto, the following usage restrictions apply for the telephony: Calls can only be made through the connected smartphone. Telephony with code 380 (Car telephony package) is not possible.
If an integration standard is activated, the head unit supports the smartphone apps in the following manner:
- Volume adaptation for all audio signals
- Forwarding of control signals to smartphone
- Use of hands-free system by the smartphone
- Forwarding of audio output to the speaker system
- Mute function, e.g. with smartphone telephony
- Forwarding of position data to smartphone
- Forwarding of video signals generated by the smartphone to the Audio/COMAND display
- Forwarding of status information for displaying in the instrument cluster (A1)
The smartphone applications themselves are not shown in the instrument cluster.
Evaluating and forwarding control signals
The head unit receives the operation signals of the upper control panel control unit, the left lower control panel (N72/4) (model 257), the right lower control panel (N72/5) (model 257) or the Drive Unit control unit control unit (N145/1) (model 290) via the telematics CAN (CAN A), evaluates them and transmits function-specific CAN messages to the user interface CAN (CAN HMI). When the DYNAMIC SELECT switch (N72/4s1) is operated, the head unit also shows the selected transmission mode on the audio/COMAND display.
Reading in of input signals as well as actuation of output media and system components
The head unit transmits and receives signals via the following connections:
- CAN
- Media Oriented System Transport (MOST)
- Direct line
- Ethernet
CAN
The head unit communicates over the telematics CAN with the following component parts:
- Audio/COMAND control panel (A40/9) (except code 446 (Touchpad only)):
Operation signals, communication with the upper control panel control unit, the left lower control panel (model 257), the right lower control panel (model 257) or the Drive Unit control unit (model 290)
- Touchpad (A105) (with code 446 (Touchpad only)):
Operation signals, communication with the upper control panel control unit, the left lower control panel (model 257), the right lower control panel (model 257) or the Drive Unit control unit (model 290)
- Touchpad (with code 448 (Touchpad)):
Control signals
- Mobile phone cradle control unit (N123/8) (with code 899 (Multifunction telephony)):
Charging requests, status of charging process, communication for drive authorization (with code 896 (Vehicle access and drive authorization through mobile phone))
- Telephone control unit (N123/9) (model 290 with code 380 (Car telephony package)):
Status of SIM card (Subscriber Identification Module) in telephone control unit
- Touchscreen (A105/3) (model 290 with code 224 (Design individual rear seat system))
- Rear passenger compartment mobile phone cradle control unit (N123/10) (model 290 with code 898 (Wireless charging in rear passenger compartment))
The head unit is a user interface CAN user:
- The user interface CAN is used by the head unit to receive, e.g. from the electronic ignition lock control unit (N73) the signals from the head unit multifunction steering wheel button group (S163/2) and the control signals for the displays in the upper control panel control unit.
- Via the user interface CAN, the head unit sends e.g. navigation displays to the instrument cluster or the signals from the upper control panel control unit, from the left lower control panel (model 257) and from the right lower control panel (model 257) to the electronic ignition lock control unit.
Media Oriented System Transport (MOST)
The head unit exchanges data with the following control units via MOST:
- Midline sound system amplifier control unit (N40/2) (model 257.361, model 290 except code 810 (Sound system) and except code 811 (Advanced Sound System))
- Sound system amplifier control unit (N40/3) (with code 810 (Sound system))
- Advanced Sound System amplifier control unit (N40/7) (with CODE 811 (Advanced Sound System))
- TV tuner control unit (N143) (with code 865 (TV tuner))
Direct line
The head unit is equipped with the following direct connections:
- Circuit 30t
- Circuit 31
- FM, AM, CL, DAB and KEYLESS-GO antenna amplifier (A2/18), also for the DAB 1 DAB Band III signal (input)
- FM 2, DAB and TV antenna amplifier (A2/108), also for the DAB 2 DAB Band III signal (input)
- SDARS antenna (A2/105) (with code 536 (SIRIUS satellite radio)) (Input)
- Driver hands-free system microphone (B25/20) and front passenger hands-free system microphone (B25/21) (input)
- GPS signal (Global navigation system) (Input):
- HERMES control unit (N112/9) (with code 362 (HERMES LTE) as of 01.06.2019)
- GPS antenna (A2/23) (except code 362 (HERMES LTE) or with code 362 (HERMES LTE) up to 31.05.2019)
- Audio muting (mute function) from the HERMES control unit (N112/9) (model 257 (except 257.361) with code 362 (HERMES LTE) and except code 810 (Sound system), except code 811 (Advanced Sound System)) (input)
- HSVL (High Speed Video Link) line from parking assistance systems control unit (N62) (with code 235 (Parking Pilot with PARKTRONIC), with code P44 (Parking Package)) (input)
- Bluetooth® antenna (A2/91) (input and output)
- WLAN antenna (A2/83) (input and output)
- Multimedia connection unit (A90/5) (input and output)
- Rear passenger compartment multimedia connection (A90/7) (model 290) (input and output)
- Front center console USB port (with code 896 (Vehicle access and drive authorization through mobile phone), code 897 (Wireless mobile phone charging) or code 899 (Multifunction telephony)) (input and output)
- Digital instrument cluster full display fan motor (M4/12), actuation and diagnosis (with code 464 (Digital instrument cluster full display)) (input and output)
- Dedicated Short-Range Communications control unit (A50/6) (with code 498 (Japan version)) (Input and output)
- Wake-up for MOST (output)
- HSVL line for video data to Audio/COMAND display (output)
- HSVL line for video data to instrument cluster (with code 464 (Digital instrument cluster full display)) (output)
- Telephony activation signal (Output):
- Telephone control unit (model 290 with code 380 (Car telephony package))
- Mobile radio antenna amplifier/compensator (A28/15) (with code 899 (Multifunction telephony))
- Mobile phone cradle control unit (with code 899 (Multifunction telephony))
- Antenna changeover switch for telephone and Active Parking Assist/stationary heater (A2/155) (model 290 with code 380 (Car telephony package) or with code 899 (Multifunction telephony) and with code B24 (Remote control for stationary heater) or with code 503 (Pre-installation for Remote Parking Pilot))
- Audio output (speaker) (model 257 (except 257.361) except code 810 (Sound system) and except code 811 (Advanced Sound System)), for vehicles with code B63 (Sporty engine sound) over the engine sound control unit (N40/1) (output)
- Microphone output to HERMES control unit (with code 362 (HERMES LTE)) (output)
Ethernet
The head unit is connected by Ethernet to the diagnostic connector (X11/4).
Structure
The following components are integrated in the head unit:
- Arithmetic unit
- Hard disk with searchable database for audio files, including cover art, cover flow and Gracenote Database
- Bluetooth® receiver
- WLAN receiver (Wireless Local Area Network)
- 3 radio tuners for AM reception, FM phase diversity and separate FM tuner function for data services, e.g. traffic messages
- HD radio tuner (High Definition) (with code 494 (USA version))
- SDARS tuner (Satellite Digital Audio Radio Service) (with code 494 (USA version))
- DAB dual tuner (Digital radio) (except code 498 (Japan version) and except code 494 (USA version))
- 4-channel audio amplifier
- GPS receiver
- Gyro sensor and 3D acceleration sensor
- Navigation processor and traffic data recorder
- Control unit for voice control system
- Head unit electrical fuse (A26/17f1) (20 A) to the rear panel
| Wiring diagram of head unit | PE82.85-P-2110-97XBB |