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8/2/2019 In-Vehicle Networking MOST

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D.Muralidar

TIFAC-CORE

VIT-UNIVERSITY


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Media Oriented System Transport


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Basic principle of MOST

MOST is a function oriented high-speed multimedia technology to network

a variety of devices

MOST defines mechanisms for sending streaming data and packet baseddata, and provides a complete application framework to control interaction

between devices in a clearly structured way.

MOST supports different speed grades and physical layers.


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A MOST system consists of up to 64 nodes.

MOST is a synchronous network: The Timing Master provides the systemclock with a continuous data signal.

All other devices the Timing Slaves synchronize their operation to thisbase signal.

Within the synchronous base data signal, the content of multiple streamingconnections and Control Data are transported.

Control Channel is used to initiate the Streaming Data connection betweensender and receiver


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Basic principle of MOST The bandwidth allocated for the Streaming Data connections is always

available and reserved for the dedicated stream so there are no

interruptions, collisions, or delays in the transport of the data stream.

MOST is designed for high quality of service and efficient transport of

audio and video

Internet traffic or information from a navigation system is typically sent in

short (asynchronous) packets and is often transported to many differentplaces.


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To accommodate such signals, MOST has defined efficient mechanisms for

sending asynchronous, packet based data in addition to the Control Data

and the Streaming Data.

These mechanisms run on top of the permanent synchronous data signal.

However, the transmission of packet based data is completely separate

from the Control Channel and the Streaming Data so that none of them

interfere with each other.

MOST is a network that has mechanisms to transport all the various signals

and data streams that occur in multimedia and infotainment systems.


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MOST Today

The big three U.S. automakersGeneral Motors (GM), Ford, and

Chryslerare actively evaluating the MOST system for their future cars,

with GM reportedly now moving beyond the evaluation stage.

Some 58 car models worldwide are using MOST, including five recently

introduced Asian models (As per 2009 data)

Many of the parts required for the electrical and optical physical layers ofthe protocol are in production.


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MOST Today..

Today, about 10% of cars worldwide in production use MOST.

Most of these cars are high-end vehicles.

The next-generation low and mid-range cars are expected to subscribe to

the MOST concept as manufacturing efficiencies of supplied parts increase,

decreasing costs.

Another key is the automotive industrys adjustment to working with the

optical fiber technology that forms MOSTs backbone.


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Major factors

Cost was a major reason, difficulty of dealing cost-effectively with the

optical to- electrical and electrical-to-optical (OEO) conversion circuitry

required.

The 58 car models mentioned previously are now all using plastic optical

fibers

Another factor has been the industrys resistance to work within an optical

environment, since such systems require a new way of servicing opticalcomponents like cutting, splicing, tapping into optical lines, and measuring

their signals, requiring new types of tools to do so


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Overview of data transports

For transmitting data, a MOST network provides the following types of data

transport mechanisms with different characteristic properties.

Control channel

Streaming data

Packet data channel


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Control channel

Data packets (for control messages) are transported to specific addresses.

The Control Channel is secured by the Control Channel CRC and has anACK/NAK mechanism with automatic retry.

It is generally specified for event-oriented transmissions at low bandwidth

and short packet length.


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Streaming data

Continuous data streams that demand high bandwidth and require time-

synchronized transmission (typically multimedia data, such as audio or

video) are transported using Streaming Data connections.

The connections are administered dynamically through appropriate control

messages.

Available bandwidth for Streaming Data connections be administered in a

central manner, particularly in larger networks.

Administration of the streaming resources is, in this case, handled by a

Connection Manager that is responsible for all requests for establishing

connections


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Packet data channel In contrast to the Control Channel, the Packet Data Channel is specified for

transmissions requiring high bandwidth .

It is mainly used for transmitting data with large block size (e.g. Graphics,picture formats, and navigation maps).

Just like the Control Channel, the Packet Data Channel is secured by CRC

(Packet Data Channel CRC) and has an ACK/NAK mechanism with

automatic retry.


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MOST device model

A MOST device is a physical unit that can be connected to a MOST network via a

MOST Network Interface Controller.


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Function block

On the application level, a MOST device contains multiple components that are

called function blocks (FBlocks), for example, tuner, amplifier, or CD player.

It is possible that there are multiple FBlocks in a single MOST device, such as a

tuner and an amplifier combined in one case and connected to the MOST network

via a common MOST Network Interface Controller

In addition to the FBlocks, which represent applications, each MOST device has a

special Fblock called the NetBlock.

The NetBlock provides functions related to the entire device.


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Function block

Between the FBlocks and the MOST Network Interface Controller, the

Network Service forms an intermediate layer providing routines to simplify

the handling of the MOST Network Interface Controller.

Each FBlock contains a number of single functions. For example, a CD

player possesses functions such as Play, Stop, Eject, and Time Played.


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Function block

Interaction with an FBlock requires two partners which are distributed over the

MOST network: The Controller and the Slave.

The FBlock functionality resides in the Slave.

The Controller sends commands to a Slave and in return receives reports from the

Slave.

The Slave executes the commands issued by a Controller and sends status reports

to the Controller.

Controllers that have an interface to the user are called Human Machine Interfaces

(HMIs).

Devices are commonly classified as HMI, Controller, or Slave with respect to their

primary function.


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MOST functions

Functions are grouped together in FBlocks with respect to their contents.

Therefore, FBlocks are references for external applications to localize a

certain function.

A function is addressed in an FBlock.

In order to distinguish between the different FBlocks and functions (Fkts)

of a device, each function and FBlock has an identifier:

FBlockID.FktID


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MOST function When accessing functions, certain operations are applied to the respective

function.

The type of operation is specified by the OPType.

The parameters of the operation follow the OPType, resulting in the

following structure:

FBlockID.FktID.OPType(Data)


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Methods and properties

A function is a defined attribute of an FBlock through which it

communicates with the external world.

Functions can be subdivided into two categories:

Functions that can be started and which lead to a result after a certain

period of time. These functions are called methods.

Functions for determining or changing the status of a device, which refer to

the current properties of a device. These functions are called properties.


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Methods

Methods can be used to control FBlocks.

In general, a method is triggered only once at a certain point of time, for

example, starting the auto-scanning of a tuner.

Methods can be defined without parameters or with certain parameters

that specify their behavior


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Methods

After finishing the process, the controlled FBlock should report execution

to the Controller.

This report may contain results of the process, for example, a frequency

found by the tuner.

If a process runs for a long time, it may be useful to return intermediate

results before finishing, such as informing the Controller about the

successful start of the process.


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Properties

Properties can be read (e.g., temperature), written (e.g., passwords), or

read and written (e.g., desired value for speed control).

Within an FBlock, a property represents a value or a status.


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Properties setting

Example : Temperature setting of a heating control.

Function Temp is a member of the FBlock Heating, so the HMI sends the

instruction Heating.Temp.Set(27) to FBlock Heating


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Reading a Property

In order for the HMI to display the current temperature, the value of

function Temp in FBlock Heating must be read.

Therefore, the HMI sends the instruction Heating.Temp.Get.


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Setting and getting the property


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OPType


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Addressing MOST functions

In a MOST network, the devices are connected in a ring structure.

To address these devices, different types of addresses can be used.

The MOST Network Interface Controller provides six different types ofaddresses

Internal Node Communication address

Node position address (RxTxPos)

Logical node address (RxTxLog) Group address

Broadcast address

Ethernet MAC address


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Communication between two devices


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FblockID

The FBlockID is the identifier of a special FBlock.

Every FBlock with a certain FBlockID must contain certain specificfunctions.

System Specific proprietary FBlockIDs can be used by a System Integrator(e.g., a car maker).

They are specific for a system and are coordinated by the System Integrator

between the suppliers developing devices for this system.

A second kind of proprietary FBlockIDs are called Supplier Specific.

Those FBlockIDs can be used by suppliers for any proprietary purpose


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FblockID


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InstID

There may be several equal FBlocks with the same FBlockID in the system

(two CD changers, four active speakers, several diagnosis blocks, etc.).


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Example for communication between 2 devices

CD.1.Track.Set(10)

???.CD.1.Track.Set(10)

CDC.CD.1.Track.Set(10)

HMI.CDC.CD.1.Track.Set(10)

HMI.CD.1.Track.SetGet(10)

HMI.CD.1.Track.Status(10)

CDC.HMI.CD.1.Track.Status(10)

CDC.CD.1.Track.Status(10)


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TERM END LAB EXAM SCHEDULE

25.05.12(Wednesday) -- Roll No. 1 to 10 2.00 to 4.30 PM

-- Roll No. 11 to 21 4.45 to 7.15 PM

26.05.12(Thursday) -- Roll No. 22 to 31 - 2.00 to 4.30 PM-- Roll No. 32 to 41 4.45 to 7.15 PM


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Marks split-up

Design(block diagram/program) 20 Marks

Output 50 Marks

Viva-voce 10 Marks

Observation 10 Marks

Procedure/explanation 10 Marks

Total 100 Marks


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Instructions for term end lab exam

Be in lab 5 minutes earlier to your scheduled examination time

Observation note should be compulsorily submitted before getting the

question paper.

After getting the question paper/answer sheet fill up all the columns

Make the design(block diagram/program) for both the questions

Then get the proceed sign to proceed further

Take your time to get your output, if you got the output for one question

get the verification sign(Verified) immediately then proceed to next

question.

Once you got your outputs, you can start writing viva-voce,

procedure/explanation

If you get a part of your output ,you have to get Partial output sign


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Spend your time to get OUTPUT, I will give sufficient time to write once you

have got output (that means you can spend atleast 2 hrs for getting

output)

For example,

Design 30 minutes

Lab view implementation 20 minutes

connecting hardware and verifying Output 15 minutes

Program typing 40 minutes

connecting hardware and verifying Output 15 minutes

Total time 120 minutes

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