Navigation processor, function - GF82.85-P-3103-07TA

During navigation mode the navigation processor (N41/1) supplies all the necessary data and information to the COMAND operating, display and control unit (A40/3). All the calculations for location finding, route calculation and navigation are performed in the navigation processor (N41/1).

Switching on/off characteristics 

As soon as a driver door is opened, navigation is automatically activated via the engine compartment CAN (CAN-C) and with it the location finding is initiated. If no status change of "circuit 15C or circuit 15R ON" occurs at the electronic ignition switch control unit (N73) for a certain amount of time, then the navigation processor (N41/1) remains activated for t = 30 min.

Function conditions for route calculation and navigation:

• Control unit within the specific temperature and voltage values
• Circuit 15R ON
• MOST woken-up

After powering the MOST ring down the navigation processor (N41/1) remains in stand-by mode for t = 30 min, then it independently goes into sleep mode. This also applies to the output of the data medium.

When a CD or DVD is loaded into the navigation processor (N41/1) only the data medium is accepted. No download, stand-by-mode or wake-up of the MOST is started.

The following information is included on the data medium:

• Navigation data basis for location finding, route calculation and navigation
• Data for dynamic navigation system
• Data on map presentation
• Index data base for destination and location for destination and location input
• Expanded data for the journey guide data
• Data for the voice output

Communication via MOST 

The information exchange between the navigation processor (N41/1) and other components takes place entirely via the MOST.

Software download 

The minimum equipment stored in the COMAND operating, display and control unit (A40/3) is a bootstrap driver, which cannot be overwritten.

The bootstrap driver is able to load a software application from the navigation DVD. This ensures the compatibility between the navigation software and the database.

The software download process from the DVD becomes unstable if differences in version are found between the flash memory and DVD.

The update process is shown to the user by a display of the progress of the software update. The navigation cannot be operated during this phase.

The other components on the MOST are not influenced during this download.

External information 

The audio gateway control unit (N93/1) supplies the information to the MOST, which is available on-board on the CAN interior (CAN-B).

The following information is required as a minimum:

• Status of circuit 15R, circuit 15, and the left front door contact switch (S17/3)
• Wheel revolution and wheel direction of rotation
• Diagnosis messages

Self-diagnosis 

Individual partial functions and navigation components are monitored while the COMAND operating, display and control unit (A40/3) is switched on and while the COMAND operating, display and control unit (A40/3) is operated. Faults are stored in the fault memory and can be read out during a service.

Destination memory, intermediate destinations and memory points 

The administration of destination memories, address books, and intermediate destinations is not accomplished in the navigation component, but in the COMAND operating, display and control unit (A40/3).

Map display 

The map presentation is always controlled by the COMAND operating, display and control unit (A40/3).

GPS control unit 

The GPS control unit is part of the navigation processor (N41/1). It evaluates the satellite signals that are emitted by the GPS antenna (A2/49a2) with model 211.0, or the GPS antenna (A2/23) with model 211.2, and uses these signals to calculate the vehicle's position.

Gyrosensor 

The yaw rate sensor (gyro sensor) determines the change in direction of the vehicle. It is built into the navigation processor (N41/1). Calibration is not required.