Operating, display unit with control unit, function - GF82.85-P-3114-08PMU

Processing button actuations 

The actuations of the control buttons and switches on the function keypad on the COMAND operating, display and control unit (A40/3) are read in over a microcontroller and transferred to the central computer. Depending on the system function, the button actuations are processed in the central computer or transferred to the other system components via the Media Oriented System Transport (MOST) and the Controller Area Network Bus Class B (interior) in the form of a data telegram to other system components.

Graphic editing and image output 

The video subsystem takes over editing and output of the control displays. The operating screens are output by the graphic subsystem internally via the FBAS signal input to the display. The FBAS signal contains the information and amplitudes for the three primary colors of red, green and blue, and a synchronization signal.

The control electronics in the display unit evaluate the signal and control the display of individual dots ("pixels") line by line in terms of color and intensity. At the end of each line a pulse that synchronizes the horizontal picture signal occurs. The electronic circuitry of the display unit then starts the next line. When the last line of the display is reached, an impulse that synchronizes the vertical picture signal occurs, and the electronic circuitry starts the first line again.

Audio signal output 

The audio signals from the various sources (CD, voice output for navigation, etc.) are processed by the COMAND operating, display and control unit (A40/3) and amplified before being output over the vehicle speakers. Final amplification of the audio signals is accomplished by the sound amplifier (A2/13). For this purpose, the audio source data are digitally transferred to the sound amplifier (A2/13).

Diagnosis interface and error management for the MOST components 

When the COMAND operating, display and control unit (A40/3) is active, the system stores all errors that occur in the non-volatile memory. These data can be read out via STAR DIAGNOSIS. Output of the errors on the display unit is not possible.

Error management also includes the components connected to the MOST. Each MOST component has its own fault memory. Upon request from STAR DIAGNOSIS, the errors are transferred via the MOST to the COMAND operating, display and control unit (A40/3) and can be read out from there with the data link connector (X11/4).

Navigation processor and Global Positioning System (GPS) control unit 

The navigation processor is the central component of the navigation system.

It is integrated in the COMAND operating, display and control unit (A40/3) and calculates the location of the vehicle from the incoming signals. It also calculates the vehicle's route after the destination has been entered. The GPS control unit is part of the navigation processor. It evaluates the satellite signals coming from the GPS antenna (A2/23) and calculates the vehicle position from this information.

Digital versatile disk (DVD) and DVD disk drive 

The integral DVD disk drive can be used to read data from the special navigation DVD or play an audio CD.

The following data are contained on the navigation DVD:

• Program data for execution in navigation processor
• Voice data for voice output
• Map data.

The digitized map area on the DVD contains towns, cities, streets, intersections and their attributes (e.g. one-way streets, turn prohibitions). It does not contain information about company and private land, farms, housing estates and paths.

Gyrosensor 

The gyrosensor determines vehicle direction changes. It is installed in the navigation processor. Calibration is not required.

The traffic data memory 

The integral traffic data recorder receives traffic messages via the MOST (in Starguide mode). The incoming data are stored in the traffic data recorder (up to 100 messages) for a maximum of 30 minutes, also during the run-on time for the COMAND operating, display and control unit (A40/3).

The traffic data memory decodes the messages and transfers them to the navigation processor as required. For synchronization, the traffic data recorder requires a current "location list" from the navigation processor. In the location list, each stretch of road and each major point (e.g. highway exit) of the road system that is being monitored in terms of traffic density is uniquely identified by means of a number. This list is originally stored on the DVD.

If required (such as when the DVD is changed), it is automatically loaded into the non-volatile traffic data recorder by the navigation processor.

The components required for navigation depend on code (530) COMAND APS USA (with navigation).