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

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 Digital Data Bus (D2B) or the Controller Area Network Bus Class B (interior) (CAN-B) in the form of a data telegram.

Graphic editing and image output 

The video subsystem takes over editing and output of the control displays. The operating screens are transmitted internally to the display by the graphic subsystem via the RGB output (R = red, G = green, B = blue).

The information and amplitudes of the 3 basic colors red, green and blue as well as a synchronization signal are included in the RGB signal.

The electronic circuitry in the display unit evaluates the RGB signal and controls the display of individual dots ("pixels") line by line in terms of color and intensity. A horizontal synchronization pulse occurs at the end of each line. The electronic circuitry of the display unit then starts the next line. After reaching the last line of the display, the vertical synchronization pulse 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 D2B 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 D2B. Each D2B component has its own DTC memory. Upon request from STAR DIAGNOSIS, the errors are transferred via the D2B 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).

The integral navigation processor uses the incoming signals to calculate the position and, after input of the destination, the route for the vehicle. 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.

CD and multi-standard disk drive: 

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

The following data are contained on the navigation CD:

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

The digitized map area on the CD 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 D2B (in Starguide mode). The 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 integral 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 location list is originally stored on the CD. If required (such as when the CD is changed), it is automatically loaded into the non-volatile traffic data recorder.