4. Audio & Video Buses
• Audio and video distribution is becoming common in motor
vehicles
• Digital Audio - CD, MP3, Navigation system, video games, DVDs,
etc.,
• Pure video transmission from camera, video digital streaming,
and distribution of video signals inside the passenger cabin
• I2C (Inter-Integrated Circuits) Bus – Philips Semiconductors : To
provide links for control commands between car radio and CD
changer
• D2B (Domestic Digital) Bus – Philips: To transfer digital audio data
to car radio from conventional audio players
• MOST – Media Oriented Systems Transport: For Audio & Video
Distribution inside the vehicle
• In addition to conventional audio applications, a car must now be
provided with:
Navigation system, Voice/Image Recognition, Mobile
Communication ., etc.,
5. MOST history
• High-speed multimedia network technology optimized by the
automotive industry
• The first multimedia installation based on MOST bus and
protocol was introduced in the year 2001.
• In the same year, MOST bus was applied in the next ten vehicle models
• In 2013, MOST was implemented in 140 vehicles
• MOST technology is used in almost every car brand worldwide,
including Audi, BMW, General Motors, Honda, Hyundai, Jaguar, Lancia,
Land Rover, Mercedes-Benz, Porsche, Toyota, Volkswagen, SAAB,
SKODA, SEAT and Volvo.
Founders
• BMW
• Daimler Benz
• Harman/Becker Automotive Systems- automotive subcontractor
• SMSC (Standard Microsystems Corporation) - semiconductors
• Audi
6. Infotainment in Vehicle
• Multimedia processing, including terrestrial and satellite radio
and local media interfaced by hard connection, USB, or
Bluetooth
• Embedded navigation including GPS/GNSS/gyro dead
reckoning
• Hands-free phone/communications
• I/O control of vehicle functions (climate, preferences, etc.)
• Rear view camera integration and display
• Audio post-processing
• Integration of functional peripherals such as tuners, GPS,
display, USB, etc.
• Management of multimodal HMI functionality, including
speech, tactile, and display-based interactions
And many more to follow….
7. MOST Concept
• A network for distribution of infotainment within vehicles
• A network can consist of up to 64 devices
• Each distributed frame can consist of three parts
- Synchronous channel for streamed data Sample rates of
44.1 or 48 kHz
- Asynchronous channel for packet distributed data
- Control Channel for control and low speed data
• Two versions
- MOST25 with optical transport media, 60 Bytes of
data/frame
- MOST50 with optical or electrical transport media,
117 Bytes of data/frame
8. MOSTchannels
• Control Channel - For event-oriented transmission with low
bandwidth (10 kBits/s) and short package length
• Asynchronous Channel - Packet oriented transmission with
large block size and high bandwidth
• Synchronous Channel - Continous data streams that require
high bandwidth
11. MOST-Features
• MOST bus is a unique solution
because it is based on ring topology
(Majority is Linear Bus Topology)
• The application of fibre optic solution
is another specific feature
• The data block received from
preceding node is used as information
and commands source.
• The block received from preceding
node is regenerated and forwarded.
• Turned off devices transmit optical
signal without its analysis.
• The data transfer is finished when the
block is received by its sender.
• The ring contains some special nodes
responsible for the ring management
13. MOST Devices
A MOST device consists of three parts
• Physical interface
• Network Services
- A Network Interface Controller (NIC) handles
these services.
- Modern NICs have a built in processor and
are called INICs, Intelligent NICs
• Function Blocks (FBlocks)
- These take care of the services
that the device can supply
14. • The MOST specification defines the physical and the data link
layer as well as all seven layers of the ISO/OSI-Model of data
communication. The MOST specification follows the OSI model
15. PhysicalLayerandMedium
• Copper Twisted pair Fibre Optic Medium
• POF (Plastic Optical Fibre) – Fibre made from a Polymer
• Wider applications & Great Immunity
• Transmitter – PIN diode , LED and Physical interface with POF
• POF Connector – Specially Designed for protection
Fig: Digital data input and MOST physical Layer Interface
16. MOST network
• Timing Master - Controls the timing of the network and
thereby the synchronization between the devices
• Network Master - Sets up the network and allocates addresses
to the devices
• Connection Master - Sets up the synchronous communication
channels between devices
• Power Master - Monitors the power supplies. Handles power
up and shut down
17. MOST25 - Features
• Optical network with a bit rate of just under 25 Mbits/s
• Sampling rate 44.1 or 48 kHz
• Each frame consists of 512 Bits (64 bytes)
• A block consists of 16 frames
• One frame can hold 60 Bytes of data
• 24 – 60 Bytes of the data can be synchronous data
• The rest of the 60 Bytes holds asynchronous data
• On top of that the Control Channel can hold 2 Bytes of
data
• The total amount of Control Channel data (32 Bytes)
is spread out over 16 frames (one block)
21. MOST 50 - Features
• Optical or electrical network with a bit rate of just
under 50 Mbits/s
• Sampling rate 44.1 or 48 kHz
• Each frame consists of 1024 Bits
• The frame can hold 117 Bytes of data
• The border between synchronous and asynchronous data can
change dynamically
• The Control Channel can hold 4 Bytes of data
• The total amount of Control Channel data (64 Bytes)
is spread out over 16 frames (one block)
