Operating, display unit with control unit, function - GF82.85-P-3114-08SKU
Processing key signals
The control buttons and switches on the function keypad on the COMAND operating, display and control unit (A40/3) are read in via the microcontroller I/O ports and transferred to the central processor. Depending on the system function the button operations undergo further processing in the central computer or are passed on to the other system components via the Media Oriented System Transport (MOST) and the class B (interior) Controller Area Network Bus (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 output on the display internally by the graphics subsystem via the Color Video Blank Sinc (CVBS) signal input. The CVBS signal contains the information and amplitudes of the 3 basic colors of red, green and blue and a synchronization signal.
The actuation electronics in the display unit evaluates the CVBS signal and actuates the color and intensity of the individual pixels line by line. There is a pulse at the end of each line which synchronizes the horizontal video signal. The electronic circuitry of the display unit then starts the next line. When the last line of the display is reached the vertical synchronization pulse is issued and the electronic circuitry starts again at line 1.
Audio signal output
The audio signals from the various sources (CD, navigation system voice output etc.) are prepared by the COMAND operating, display and control unit (A40/3n1) and amplified before being output via the vehicle loudspeakers by the audio gateway control unit (N93/1).
Info menu
The information menu is accessed directly using the "i" or "INF" key. This functionality can be selected independently of source (e.g. from the telephone or radio menu). Pressing the "Back" key returns you to the screen from which the Info menu was selected. If "Mode" item was selected in the Info menu, the system switches to the screen preceding the Info menu when confirming with the "Back" key.
Diagnostic interface (K-line) and fault management
While the COMAND operating, display and control unit (A40/3) is active, the system saves all faults that occur in the non-volatile memory. These faults can be read out using STAR DIAGNOSIS via the data link connector (X11/4). Output of the errors on the display unit is not possible. The diagnosis also includes the components connected to the MOST ring. Each MOST component has its own fault memory.
The faults are transmitted to the audio gateway control unit (N93/1) via the MOST by means of a STAR DIAGNOSIS request and can then be read out.
Position finding
The COMAND operating, display and control unit (A40/3) communicates with the navigation processor (N41/1) via the MOST for position calculation. Signals from at least 4 satellites are required for the first position calculation; signals from 3 satellites are sufficient for subsequent calculations. If these position calculation prerequisites are not met, only the number of received satellite signals is displayed on the COMAND operating, display and control unit (A40/3).
Digital Versatile Disk (DVD) and DVD-ROM disk drive
DVDs or audio CDs can be played using the integrated DVD-ROM drive.