LEMON Manuals: Even more car manuals for everyone
Home >> Mercedes Benz >> 2016 >> E400 Base, 2D Convertible >> Repair and Diagnosis >> Electrical >> Motors, Switches, Relays >> Electrical System - Body - 212 Chassis - 2 Of 8 >> Basic Knowledge >> Audio mode, function >> Audio mode, function - GF82.85-P-2030FLM

Audio mode, function - GF82.85-P-2030FLM

MODEL 212 as of 3/2/15 as of model year 2016 

Illustration shows model 212 

Fig 1: Audio Mode Function Diagram
G10050563Courtesy of MERCEDES-BENZ USA

Function requirements, audio mode, general 

General information on the audio mode 

The audio mode consists of the following component functions:

The audio mode can be operated using the following controls:

Menu guidance and the display of additional information are carried out on the Audio/COMAND display. The Audio/COMAND display is switched on by the audio equipment via telematics CAN. The picture signals are received by the Audio/COMAND display over the low voltage differential signaling line from the audio equipment.

On vehicles except CODE 810 (Sound system) and CODE 811 (Advanced sound system), the audio equipment outputs the audio signals via the vehicle's speaker system.

On vehicles with CODE 810 (Sound system) or CODE 811 (Advanced sound system), the audio signals are forwarded via the MOST to the sound system amplifier control unit, which then actuates the speaker system.

IMPORTANT More detailed information on the speaker system is available in the "Speaker output function" document.

Function sequence for volume/tone settings 

All volume and tone settings are performed using the audio equipment. This is performed either by the user or automatically by the audio unit.

The volume and tone settings are shown on the Audio/COMAND display. The sound settings can be changed with "Tone" and the system returned to the default settings in the system settings menu. On vehicles with CODE 810 (Sound system) or CODE 811 (Advanced sound system), the audio equipment is equipped with additional tone settings along with the generally available ones (treble, bass and balance).

The volume and tone setting partial function is subdivided into the following subfunctions:

Function sequence for manual volume/sound settings 

The manual volume/tone settings function is subdivided into the following sequences:

On vehicles with CODE 810 (Sound system) or CODE 811 (Advanced sound system), the desired settings are forwarded via MOST to the sound system amplifier control unit where they are processed. On vehicles except CODE 810 (Sound system) or CODE 811 (Advanced sound system), the selected settings are processed in the audio equipment. Audio output through the speaker system can be muted using the mute function button on the multifunction steering wheel or the corresponding button on the audio equipment.

Function sequence for volume settings via right multifunction steering wheel button group 

The volume for the audio and video sources is increased or decreased by pressing the + and - buttons, selecting specific functions and volume control. The control signals are forwarded to the audio equipment via the following route:

Function sequence for volume settings through the audio equipment 

Turning the control on the audio equipment increases or reduces the volume.

Function sequence for sound settings via audio/COMAND control panel 

The user can set the corresponding sound by selecting the "Sound" menu on the audio/COMAND control panel.

The Audio/COMAND control panel control signals are sent via the telematics CAN to the audio equipment.

Function sequence for speed-dependent volume control (SDV [GAL]) 

The volume is adapted to the noise level in the vehicle interior using the speed-dependent volume control, which is defined by the vehicle speed.

In order to make this adjustment, the instrument cluster sends vehicle speed information to the audio equipment via interior CAN. In vehicles with CODE 810 (Sound system) or CODE 811 (Advanced sound system), the audio equipment forwards the information via MOST to the sound system amplifier control unit. In accordance with this information the audio equipment or the sound system amplifier control unit raises the output level or lowers it.

On vehicles with CODE 811 (Advanced sound system), the SDV is additionally optimized by using the sound system microphone. The sound system amplifier control unit reads in the signals of the sound system microphone, evaluates the signals, and adjusts the volume of the audio signals to the interior or driving noises.

Function sequence for radio operation (FM, AM, HD radio) 

The antennas receive signals for the frequency bands FM (ultra-short wave band (FM)) and AM (medium wave (MW) and - not for all national versions - short wave band (SW)). The following useful signals relevant for the radio reception are modulated onto these signals:

The FM-1 signals are received via direct lines from the audio equipment via the following route:

The FM-2 signals are received via direct lines from the audio equipment via the following route:

The AM signals are received via direct lines from the audio equipment via the following route:

The radio mode function sequence consists of the following subfunctions:

AM tuner function sequence 

For the MW and LW radio frequency bands, the useful signals are broadcast using amplitude modulation (AM). The AM tuner integrated into the audio equipment demodulates these signals. In other words, it separates the useful signals (audible frequencies) from the carrier signal (inaudible).

IMPORTANT MODEL 212 as of 3/2/15

as of model year 2016

with CODE 494 (US version)

MODEL 212 as of 3/2/15

as of model year 2016

with CODE 498 (Japanese version)

Only MW frequencies are received in the AM frequency range.

Function sequence for FM double tuner with diversity reception (FM) 

For the FM radio frequency band, the useful signals are broadcast using frequency modulation (FM).

The dual FM tuner integrated into the audio equipment demodulates these signals. In other words, it separates the useful signals (audible frequencies) from the carrier signal (inaudible). The audio equipment integrates the signals from the FM 1, AM, CL [ZV] and KEYLESS-GO antenna amplifier and from the FM 2 and DAB antenna amplifier to form an optimized signal (phase diversity).

IMPORTANT An additional tuner function is integrated in the audio equipment for additional information such as the weatherband or FM multiplexer for the Vehicle Information and Communication System (VICS).

Function sequence for Radio Broadcast Data System (RDBS) (with CODE 494 (USA version)) or RDS (except CODE 494 (USA version), except CODE 498 (Japan version)) 

In addition to the radio program, many radio stations (FM) also broadcast additional digital information such as station name and traffic message channel recognition.

The additional digital information is evaluated by the audio equipment and shown on the Audio/COMAND display, provided that the following preconditions are complied with:

Function sequence, HD radio (with CODE 494 (USA version)) 

The HD tuner integrated into the audio equipment decodes the digital signals. Additional information and services are shown on the Audio/COMAND display, e.g. Program Service Data, Artist Experience, traffic information.

Function sequence for digital radio (DAB) (with CODE 537 (Digital radio)) 

The tuner unit permits the reception of digital radio in DAB format. The stations are categorized into groups in DAB, so-called "Ensembles".

Control of the DAB functions is accomplished via the audio equipment. The information or displays required for control are shown on the Audio/COMAND display.

The tuner unit receives a DAB band III signal (DAB 1) as follows:

The tuner unit receives a separate DAB band III signal (DAB 2) as follows:

With DAB reception, the audio equipment sends the FM station lists over the MOST to the tuner unit. If a comparable FM station is found, this is then requested by the tuner unit and the audio equipment provides the FM audio signals on the MOST. If the DAB reception worsens, a switch is made to the audio equipment's FM station, whereby the tuner unit adjusts the time lag between the digital and the analog signal. In this way the switchover is almost inaudible ("Seamless Linking").

The tuner unit sends the audio signals over MOST to the audio equipment (except CODE 810 (Sound system) and except CODE 811 (Advanced sound system)) or to the sound system amplifier control unit (with CODE 810 (Sound system) or CODE 811 (Advanced sound system)).

DAB dual tuner 

The tuner unit is designed as a diversity tuner and provides the following advantages:

Function sequence, Satellite Digital Audio Radio (SDAR) (with CODE 536 (SIRIUS satellite radio)) 

The tuner unit makes it possible to receive stations from the "Sirius satellite radio" provider. The SDAR system is controlled through the audio equipment and the control occurs via MOST. The information or displays required for control are output via the Audio/COMAND display and also in the instrument cluster.

The Sirius satellite radio signal is broadcast 3 times to achieve a diversity of channels (using two satellites and one terrestrial transmitter). The multifunction antenna receives all three channels from the Sirius satellite radio (Sat 1, Sat 2, terrestrial station) and transmits these signals over a direct line to the tuner unit.

The tuner unit receives and decodes the signals and sends them over MOST to the audio equipment (except CODE 810 (Sound system) and except CODE 811 (Advanced sound system)) or to the sound system amplifier control unit (with CODE 810 (Sound system) or CODE 811 (Advanced sound system)).

IMPORTANT Real-time traffic data (RTTD) is also transmitted via SDAR, which includes accident and congestion reports and traffic flow information. Real-time traffic data is made available to the navigation module of the COMAND controller unit via MOST.

Function sequence for DVD, CD audio 

The DVD/CD audio function enables audio CDs or audio DVDs (including MP3 and other formats) to be played.

User guidance for controlling DVD and CD functionality and displaying additional information is performed on the Audio/COMAND display. The data exchange between the audio equipment and the Audio/COMAND display takes place via the telematics CAN, but the audio equipment transmits image and video data to the Audio/COMAND display via an LVDS line.

Function sequence for connections in stowage compartment (telephone compartment) beneath the front armrest 

2 USB connectors (universal serial bus) are integrated into the multimedia connection unit and they can be used to connect external devices (e.g. USB memory stick, iPods and MTP devices). The multimedia connection unit is connected over a direct line to the audio equipment.

When connecting a device to the multimedia connection unit, the audio equipment switches over to the new media source. The audio equipment emits the audio signals from the connected devices over the speaker system (except CODE 810 (Sound system) and except CODE 811 (Advanced sound system)) or it forwards them over the MOST to the sound system amplifier control unit (with CODE 810 (Sound system) or CODE 811 (Advanced sound system)). User guidance is performed on the Audio/COMAND display. The audio equipment generates the display information and transmits it to the Audio/COMAND display via an LVDS line.

IMPORTANT MODEL 212 as of 3/2/15

as of model year 2016

with CODE 518 (Media interface)

Three adapter cables are included for connecting the external devices. Metadata is stored in the connected device in addition to the actual media files. This metadata is collected by the COMAND controller unit (with CODE 531 (COMAND APS)) in a memory, the Media Database. It is then possible to search for the relevant metadata in the media database. Metadata includes, for example, the title, interpreter, composer, album, genre, audio book, podcast, file identifier, file type (audio or video). The COMAND controller unit permanently stores the metadata for up to three devices. When one of these devices is reconnected, the metadata is updated. As soon as a fourth device is connected, the oldest set of metadata is overwritten.

When playing pieces of music, the corresponding cover art is shown on the Audio/COMAND display if the cover art in question is stored in the portable terminal (e.g. iPod). The maximum file size for processing cover art is 5 MB. The audio equipment adapts the resolution to 240 X 240 pixels, 16-bit colors, and converts the file to the JPG format. When searching for albums or pieces of music on the connected device, the matching cover art is also shown on the Audio/COMAND display.

Function sequence for SD (Secure Digital) memory card (with CODE 522 (Audio 20 radio) or with CODE 531 (COMAND APS)) 

The memory card reader is integrated in the audio equipment. Audio data stored on an SD card can be shown on the Audio/COMAND display by activating the "Memory Card" media source and played back by the audio equipment.

Additional function requirements for storing audio CDs on the COMAND controller unit (with CODE 531 (COMAND APS) and CODE 494 (USA version) or with CODE 498 (Japan version)) 

Function sequence, storing audio CDs on the COMAND controller unit (with CODE 531 (COMAND APS) and CODE 494 (USA version) or with CODE 498 (Japan version)) 

Audio CDs can be stored on the integrated hard disk of the COMAND controller unit and subsequently retrieved using the "Search" menu. The storage procedure is started during media operation by selecting "REC" in the "Media" menu bar. Only the entire audio CD can be stored on the hard disk. If the storage procedure is canceled prematurely (e.g. by selecting "Cancel"), no data is stored. Stored audio CDs can be retrieved using the "Search" menu in the "Media" menu bar. The individual tracks can also be retrieved using the general search function.

IMPORTANT Up to 12 audio CDs can be stored. When 12 audio CDs have been stored, an audio CD must be deleted before a new audio CD can be stored. In order to delete stored audio CDs, a stored audio CD must be played back. A stored audio CD can be selected for deletion using "Options" in the Media menu bar.

Function sequence for Bluetooth®audio 

The Bluetooth antenna enables the audio equipment to receive Bluetooth® audio signals from external devices. Bluetooth® audio is divided into the following subfunctions:

Search for devices and authorization 

The same options exist for the authorization of a Bluetooth® audio source as are available for telephony:

The device lists are set up the same for Bluetooth® audio and telephony. In the respective list, only those devices that support the corresponding Bluetooth® profile of the respective function are found or displayed during a search. With Bluetooth® audio these are Audio Video Remote Control Profiles (AVRCP) and Advanced Audio Distribution Profiles (A2DP), and for telephony it is the Hands-free Profile (HFP). If a device supports both functions, it is shown in both lists following authorization.

Connection and reconnection 

An authorized device can be connected by means of selection in the corresponding list. If a device is connected that supports both HFP and AVRCP/A2DP, all profiles are connected. In this case the device is a telephone and the source of Bluetooth® audio at the same time. On most devices, it is necessary to start the player on the telephone so that it can then be controlled via the audio equipment.

When starting, the audio equipment proceeds with the following strategy: First a check is performed as to whether an authorized telephone is inserted into the mobile phone cradle (with CODE 386 (Comfort telephone)). If this is the case, the audio equipment connects to the telephone and goes into the comfort telephony status. If no mobile phone cradle is present or no telephone inserted, the audio equipment searches for the last two telephones. If one of these devices is found, the audio equipment connects to this device. If this device also supports AVRCP/A2DP, these profiles are also connected.

If a device is connected that only supports HFP and a change to the Bluetooth® audio application is made, "No Bluetooth audio device connected" is shown on the audio equipment if corresponding audio sources are shown in the device list.

The "Connect last device" function bar enables the last used Bluetooth® audio source to be connected. However, the connection to the current telephone is interrupted here.

If a device is connected that only supports AVRCP/A2DP and a change to the telephone application is then made, the connection to the device is disconnected and the audio equipment begins the search for the last two telephones.

Metadata and display of information 

The display of information for Bluetooth® audio depends on the respective device used. If this device supports AVRCP 1.0 then only "Audio streaming" is shown on the Audio/COMAND display and in the instrument cluster.

As of AVRCP 1.3, the track, album and artist are shown. In addition, the currently played time of the track can also be conveyed.

Furthermore, there is the option of changing between the normal track sequence and shuffle.

IMPORTANT It is possible to jump to the next or the previous track using the left multifunction steering wheel button group.

  Electrical function schematic for Digital Audio Broadcasting function MODEL 212 with code 537 (Digital radio) PE82.60-P-2057-97DAM
  Electrical function diagram for audio mode, function   PE82.60-P-2058-97DAM
  Electrical function schematic for SDAR function MODEL 212 with code 536 (SIRIUS satellite radio) PE82.60-P-2060-97DAM
  Overview of system components, telematics   GF82.85-P-9999FLA
scientia non olet · About LEMON Manuals