Multimedia Module (Mmm) (2007-2014): Function: Navigation
The navigation section in the Multimedia module (MMM) (16/108) calculates the vehicle's position from the information from:
- GPS antenna
- wheel rotation counter
- the gyro in the multimedia module (MMM)
- reverse gear status
- map matching function.
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)
Information from these control modules is sent to the infotainment control module (ICM) (16/94), which then distributes the information to the multimedia module (MMM).
Information from the gyro and the wheel rotation counter is used to achieve better precision than the GPS position from the GPS antenna can give, and is used for dead reckoning, i. e. to calculate the position when communication is lost with the GPs satellites. This occurs when in a tunnel, for example.
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 on the steering wheel module (SWM) (3/254) are used to control the on-screen menu for navigation.
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) transmits both signals to the infotainment control module (ICM) via the low speed side of the Controller area network (CAN). In turn, it sends the signals on the MOST network to the Multimedia module (MMM).
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 select a route and display the position of the car, the map information must be on the hard disk. The Multimedia module (MMM) calculates the position and displays it on the directly connected screen. If the map information has been updated, the DVD must be left in the DVD player, otherwise the map information will not be displayed.