CAN B SIdea by

Ahmad

In The Name Of Allah

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History

The abbreviation “CAN” stands for

“Controller Area Network”.

This bus:

• Introduced by Robert Bosch in 1986.

• Developed for automotive applications

• Standardized in 1993 as ISO11898-1

• CAN Standards :

• CAN 2.0A

• CAN 2.0B

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BUS topology

What is a Network Topology

It is the arrangement of various elements [Links, Nodes,

Etc.] for a Network [a telecommunication n/w] to

exchange Data

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Car System4

Before CAN!

Windows Power

& Control

System :

Different

Speed5

After CAN!!!6

Serial vs. Parrallel

Why Serial Communication

A few advantages

A serial connection requires fewer interconnecting cables (e.g.,

wires/ fibers) and hence occupies less space.

The extra space allows for better isolation of the channel from its

surroundings.

Serial is a better option because it is cheaper to implement

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CAN vs. MultiWire Network Physical medium – two wires terminated at both ends by resistors.

Differential signal - better noise immunity.

Benefits:

Reduced weight, Reduced cost

Fewer wires = Increased reliability

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CANBUS and the OSI Model9

Summary10

Basic Configuration11

Transmission Characteristics

Up to 1 Mbit/sec.

Common baud rates: 1 MHz, 500 KHz and 125 KHz

All nodes – same baud rate

Max length:120’ to 15000’ (rate dependent)

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Message Oriented Transmission

Protocol

Each node – receiver & transmitter

A sender of information transmits to all devices on the bus

All nodes read message, then decide if it is relevant to them

All nodes verify reception was error-free

All nodes acknowledge reception

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Message Format14

Message Format15

A Programm

A message frame information :

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A Programm

Message

Information

Write

message

Read

message

Set

Write

buffer

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Bus Arbitration

Arbitration – needed when multiple nodes try to transmit at the

same time

Only one transmitter is allowed to transmit at a time.

A node waits for bus to become idle

Nodes with more important messages continue transmitting

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Bus Arbitration(2)

Message importance is encoded in message ID.

Lower value = More important

As a node transmits each bit, it verifies that it sees the same bit

value on the bus that it transmitted.

A “0” on the bus wins over a “1” on the bus.

Losing node stops transmitting, winner continues.

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Bus Arbitration(3)

Wired AND

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Bus Levels according to ISO-IS 11898

Logic 1 Logic 0

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CAN and EMI22

A Basic CAN controller

Cheap CAN controller – CPU could get overrun with messages

even if it didn’t need them.

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Full CAN Controller

Hardware message filters sort & filter messages without interrupting CPU

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An ExampleCaterpillar 797

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An Example(2)26

An Example(3)27

A CAN Controller Circuit28

CAN

Controller

& Host

Standard

CAN Port

CAN

Transiver

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Refrence

NXP LPC176x5x User manual

Ducati North America

Pedro Campana Antenna Control Specialist

Introduction to CANBUS : Marek Hajek

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