Multimedia Module (Mmm): Function: Navigation
The navigation unit of the multimedia module (MMM) (16/108) determines vehicle position based on the signals received from the GPS unit.
Information from other nodes that is used for navigation:
- wheel rotation counter from the brake control module (BCM) (4/16)
- reverse gear status from the transmission control module (TCM) (4/28) and central electronic module (CEM) (4/56)
- speed signal from the central electronic module (CEM).
Information from these control modules is sent to the infotainment control module (ICM) (3/281), which then distributes the information to the multimedia module (MMM).
The map displayed on the high level display front (HLDF) (16/46) shows the position of the vehicle. The position is adjusted using information from:
- wheel rotation counter
- speed signal
- accelerometer in the multimedia module (MMM)
- reverse gear status
- GPS antenna
- map matching function.
Information from the accelerometer and wheel rotation counter can be used for a dead estimation, that is to say to calculate position. This occurs, for example, if one loses communication with the GPS satellites when going through a tunnel.
The navigation function indicates current position and how to get to the specified destination. There is also voice guidance, which tells the driver which way to drive to get to the specified destination.
The navigation buttons of the steering wheel switch right (SWSR) can be used to navigate the navigation menu on the high level display front (HLDF).
Two signals are sent via the high speed side of the CAN network to the central electronic module (CEM):
- information from the wheel rotation counter is sent from the brake control module (BCM)
- information on reverse gear status is sent from the transmission control module (TCM)
The central electronic module (CEM) sends both signals on via the low speed side of the CAN network to the infotainment control module (ICM). Vehicle speed is also sent from the central electronic module (CEM) to the infotainment control module (ICM). ICM, in turn, sends the signals on to the multimedia module (MMM) via the MOST network.
Information for voice guidance to the selected destination is sent between the multimedia module (MMM) and integrated audio module (IAM) (16/1) via the MOST network.
In order for the multimedia module (MMM) to be able to select a route and indicate vehicle position, a DVD with the current road network must be installed in the multimedia module (MMM). The multimedia module (MMM) can then calculate the position and indicate it on the directly connected screen.