The ASK audio-system controller manages all the audio signals of the audio system. The audio system comprises the stereo, hi-fi and Top hi-fi options. The audio-system controller is the network and timing master in the MOST network.
Depending on their function, the audio sources are subdivided into entertainment and infotainment.
Entertainment: All the functions which serve entertainment purposes are assigned to "entertainment". These include radio, television and playback of video and audio recordings. The volume of the active source is adjusted by means of the combined rotary control/push button.
Infotainment: "Infotainment" comprises check control messages, the PDC gong and navigation announcements. The volume of the navigation announcements is adjusted by means of the combined rotary control/push button. The volume of the other infotainment sources is set by means of coding.
The audio-system controller (ASK) is a control unit in the MOST network. The ASK is responsible for managing all audio signals.
The following are part of the ASK: A single drive for audio data media, a combined rotary control/push button, an auto search button and an eject button.
The ASK generates a number of audible sounds, e.g. the PDC (Park Distance Control) gong.
At temperatures above 70°C the ASK shuts down. The MOST functions are then no longer available.
Control display (CD): Apart from a few exceptions, the control display incorporates the controls and displays for the entire vehicle. The control display coordinates the function requests from the system and assigns them to the relevant functions.
Controller: The control display is operated by means of the controller located at the front in the centre armrest.
Depending on the equipment version, different components are fitted. In the stereo option, the hi-fi amplifiers only amplify the audio signals for the left and right subwoofers.
In the hi-fi option, better-quality hi-fi amplifiers are fitted than in the stereo option. The hi-fi amplifiers only amplify the audio signals for the left and right subwoofers. Acoustic control is assumed by the audio system controller.
In the Top hi-fi option, the output stages for the subwoofers and the rear door speakers are integrated in the Top hi-fi amplifier. The output stages for the front door speakers and rear parcel shelf are located in the audio system controller. Acoustic control is assumed by the Top hi-fi amplifier. The Top hi-fi amplifier is a node in the MOST network.
The MOST (Media Oriented Systems Transport) bus links the audio, video and navigation systems. Information relating to function requests is transmitted to the relevant control units by means of MOST bus messages.
The aerial tuner supplies the LF signals on the MOST bus. The audio-system controller makes the audio channels available for sound output and produces the sound output (hi-fi/stereo options only).
With the Top hi-fi option, the ASK similarly provides the audio channels. However, the LF signals are processed and output by the amplifier.
The ”mute” function mutes audio output (tuner, CD player, CD changer, audio cassette playback). In CD mode, CD changer mode or audio cassette mode, the relevant player is also stopped. The mute function is activated by receipt of
If a traffic news bulletin is received when the radio has been muted, the radio is not demuted. The traffic bulletin is suppressed.
In conjunction with the Top hi-fi amplifier option, the audio system controller provides the function 7-band equalizing.
In this way, the volume is increased in a tuned sound range when the vehicle exceeds definable speed thresholds. This volume increase compensates for the noises generated by the vehicle acoustics as the car is being driven. The volume of the individual frequency bands, and particularly the lower frequencies, is individually adjusted in response to the speedometer A (output) signal.
If the stereo or hi-fi option is fitted, the volume is increased across the entire frequency band when the vehicle exceeds definable speed thresholds.
The audio entertainment function is activated and deactivated by pressing the combined rotary control/push button.
The volume of the active audio output is adjusted by turning the button. The ASK reports status changes to the control display. The control display identifies the current audio function and requests a volume adjustment by the ASK for it.
The control display is used to assign functions to the auto search button. The timers for distinguishing between short- and long-term pressing are implemented in the control display. When the button is pressed, this is forwarded as a status signal to the control display. The control display knows which function is currently being performed and assigns the status signals from the individual control units to that function. Thus, when the ASK auto search button is pressed, the Skip function for either the single drive or the CD changer is activated.
Pressing the auto search button activates the station search function.
Pressing the eject button causes the sound carrier to be ejected from the ASK single drive. The eject function is performed independently of the MOST bus.
The control display coordinates the function requests from the system and assigns them to the relevant functions.
Depending on the request, the audio-system controller selects the sources for the audio signal output. The ASK decides whether an audio signal can be overlaid by another source or completely faded out.
The control display is the only control unit which knows which function is currently active on the system. If the volume is to be increased (function request), the control display sends a telegram to that effect to the ASK. That message also contains the information indicating to which audio source the volume adjustment applies. Infotainment audio output is always a certain amount louder than the entertainment source.
In diagnosis, each individual audio output channel can be activated via the ASK control unit. The command can be reset via diagnosis or by operating an audio function.
For testing purposes, always use the CD Sound Test.
The telephone ringing tone is generated by the telephone itself. If the telephone ringer is audible when a telephone call is received, the ASK has established the connection properly. If problems nevertheless occur, they are more likely to be attributable to the telephone than to the ASK.
If the Top hi-fi option is fitted, it is therefore possible for infotainment sources to be output (except navigation) but no entertainment audio output is possible.
The ASK generates the network fault entries.
The power supply is OK if the sound carrier is ejected properly from the ASK single drive with the ”Eject” button.