AUTOMOTIVE SYSTEM

The major application domains of embedded systems are:

Consumer, Industrial, Automotive , Telecom, Etc.,
In which telecom and automotive industry holds a big market share.
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4.2.1 Inner working
• Automotive embedded systems are the one where electronics
take control over the mechanical systems.

• Automotive embedded systems are normally built around

microcontrollers or DSPs or a hybrid of the two and are
generally known as Electronic Control Units (ECUs).

• The number of embedded controllers in an ordinary vehicle

varies from 20 to 40 whereas a luxury vehicle like Mercedes S
and BMW 7 may contain 75 to 100 numbers of embedded
controllers
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The various types of electronic control units (ECUs) used in the
automotive embedded industry can be broadly classified into :

High-speed Electronic Control Units (HECUs): These are deployed

in critical control units requiring fast response. They include fuel
injection systems, antilock brake systems, engine control, electronic
throttle, steering controls, transmission control unit and central control
unit.

Low-speed Electronic Control Units (LECUs): These Units are

deployed in applications where response time is not so critical. They
generally are built around low cost microprocessors/microcontrollers
and digital signal processors. Audio controllers, passenger and driver
door locks, door glass controls (power windows), wiper control,
mirror control, seat control systems, head lamp and tail lamp controls,
sun roof control unit etc.
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Automotive Communication Buses

• Controller Area Network (CAN)

• Local Interconnect Network (LIN)

• Media-Oriented System Transport (MOST) Bus

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Controller Area Network (CAN)
• The CAN bus was originally proposed by Robert Bosch,
pioneer in the Automotive embedded solution providers.

• It supports medium speed (ISOl 1519-class B with data

rates up to 125 Kbps) and high speed (ISOl 1898 class C
with data rates up to 1Mbps) data transfer.

• CAN is an event-driven protocol interface with, support for

error handling in data transmission.

• It is generally employed in safety system like airbag

control; power train systems like engine control and
Antilock Brake System (ABS); and navigation systems like
GPS.
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Local Interconnect Network (LIN)
• LIN bus is a single master multiple slave (up to 16 independent
slave nodes) communication interface.
• LIN is a low speed, single wire communication interface with
support for data rates up to 20 Kbps and is used for
sensor/actuator interfacing.
.
• LIN bus is employed in applications like mirror controls, fan
controls, seat positioning controls, window controls, and
position controls where response time is not a critical issue.
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Media-Oriented System Transport (MOST) Bus
The Media-oriented system transport (MOST) is targeted for
automotive audio/video equipment interfacing, used primarily in
European cars.

A MOST bus is a multimedia fibre-optic point-to-point network

implemented in a star, ring or daisy- chained topology over optical fibre
cables.

The MOST bus-specifications define the physical (electrical and optical

parameters) layer as well as the application layer, network layer, and
media access control.

MOST bus is an optical fibre cable connected between the Electrical

Optical Converter (EOC) and Optical Electrical Converter (OEC),
which would translate into the optical cable MOST bus.
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Key Players of the Automotive Embedded Market

• The key players of the automotive embedded market can

be visualised in three verticals namely,

silicon providers,
solution providers and
tools and platform providers.
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Silicon Providers
• Silicon providers are responsible for providing the necessary chips
which are used in the control application development.

• The chip may be a standard product like microcontroller or DSP or

ADC/DAC chips. Some applications may require specific chips and
they are manufactured as Application Specific Integrated Chip
(ASIC).

• leading silicon providers in the automotive industry are:

Analog Devices , Xilinx , Atmel , Maxim/Dallas, NXP semiconductor,
Texas Instruments , Fujitsu, nfineon, NEC
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Solution Providers
Solution providers supply OEM and complete solution for
automotive applications making use of the chips, platforms and
different development tools.

The major players of this domain are listed below.

– Infosys Technologies
– Delphi
– Bosch Automotive
– DENSO Automotive
 AUTOMOTIVE SYSTEM
Tools and Platform Providers
• Tools and platform providers are manufacturers and suppliers of various
kinds of development tools and Real Time Embedded Operating Systems
for developing and debugging different control unit related applications.

• Tools fall into two categories, namely embedded software application

development tools and embedded hardware development tools.

• Sometimes the silicon suppliers provide the development suite for

application development using their chip. Some third party suppliers may
also provide development kits and libraries.

• Some of the leading suppliers of tools and platforms in automotive

embedded applications are listed below.

ENEA , The MathWorks , MATLAB, Keil Software , Lauterbach ,

ARTiSAN , Microsoft
 Chapter 7
Hardware Software Co-Design and
Program Modelling

In this chapter we will be studying about :

Fundamental Issues in Hardware Software Co-

Design.

Computational Models In Embedded Design.

 Fundamental Issues in Hardware
Software Co-Design
 Selecting the model
 Selecting the Architecture
– controller architecture
– datapath architecture
– Finite State Machine Datapath (FSMD)
– The Complex Instruction Set Computing (CISC)
– The Very Long Instruction Word (VLIW)
– Parallel processing architecture
 Selecting the language
Partitioning System Requirements into
hardware and software
 Selecting the model
• A model is a formal system consisting of objects and
composition rules.

• Most often designers switch between a variety of models from

the requirements specification to the implementation aspect of
the system design.

• The reason being, the objective varies with each phase; for
example at the specification stage, only the functionality of the
system is in focus and not the implementation information.

• When the design moves to the implementation aspect, the

information about the system components is revealed and the
designer has to switch to a model capable of capturing the
system’s structure.
 Selecting the Architecture
• A model only captures the system characteristics and does not
provide information on ‘how the system can be manufactured?’'.

• The architecture specifies how a system is going to implement

in terms of the number and types of different components and
the interconnection among them.

• Controller architecture, Datapath Architecture, Complex

Instruction Set Computing (CISC), Reduced Instruction Set
Computing (RISC), Very Long Instmction Word Computing
(VLIW), Single Instruction Multiple Data (SIMD), Multiple
Instruction Multiple Data (MIMD), etc. are the commonly used
architectures in system design.
• The controller architecture implements the finite state
machine using a state register and two combinational
circuits.

• The state register holds the present state and the

combinational circuits implement the logic for next state
and output.
• The datapath architecture is best suited for implementing
the data flow graph model

– A datapath represents a channel between the input and output and

in datapath architecture the datapath may contain registers,
counters, register files, memories and ports along with high speed
arithmetic units.

– Ports connect the datapath to multiple buses. Most of the time the
arithmetic units are connected in parallel with pipelining support
for bringing high performance.
 Finite State Machine Datapath (FSMD)
This architecture combines the controller architecture with datapath
architecture.
It implements a controller with datapath. The controller generates
the control input whereas the datapath processes the data.

The datapath contains two types of I/O ports:

The one acts as the control port for receiving/sending the control
signals from/to the controller unit.
The second I/O port interfaces the datapath with external world for
data input and data output.

Normally the datapath is implemented in a chip and the I/O pins of

the chip acts as the data input output ports for the chip resident data
path.
• The Complex Instruction Set Computing (CISC) architecture
uses an instruction set representing complex operations.

• It is possible for a CISC instruction set to perform a large

complex operation (e.g. Reading a register value and
comparing it with a given value and then transfer the program
execution to a new address location (The CJNE instruction
for 8051 ISA)) with a single instruction.

• The use of a single complex instruction in place of multiple

simple instructions greatly reduces the program memory
access and program memory size requirement.

• However it requires additional silicon for implementing

microcode decoder for decoding the CISC instruction. The
datapath for the .CISC processor is complex.
• Reduced Instruction Set Computing (RISC) architecture
uses instruction set representing simple operations and it
requires the execution of multiple RISC instructions to
perform a complex operation.

• The data path of RISC architecture contains a large

register file for storing the operands and output. RISC
instruction set is designed to operate on registers. RISC
architecture supports extensive pipelining.
• Parallel processing architecture implements multiple concurrent
Processing Elements (PEs) and each processing element may
associate a datapath containing register and local memory.

• In SIMD architecture, a single instruction is executed in parallel with

the help of the Processing Elements. The scheduling of the instruction
execution and controlling of each PE is performed through a single
controller. The SIMD architecture forms the basis of reconfigurable
processor.

• On the other hand, the processing elements of the MIMD architecture

execute different instructions at a given point of time. The MIMD
architecture forms the basis of multiprocessor systems.

• The PEs in a multiprocessor system communicates through

mechanisms like shared memory and message passing.
The Very Long Instruction Word (VLIW) architecture
implements multiple functional units (ALUs, multipliers, etc.)
in the datapath.

The VLIW instruction packages one standard instruction per

functional unit of the datapath.