CAN (Controller Area Network)

Mercedes-Benz Research and Development India


Controller Area Network (CAN)

SUKRUTH RAMESH BABU, EE, MBRDI Embassy Crest, Banglaore, 14-August-2015


Contents

1. Motivation2. Introduction3. CAN communication4. CAN framing5. CAN bus access6. CAN data protection

05/01/2023CAN Presentation | Sukruth Ramesh Babu


Motivation….

Intensive electronics Creating communication between electronic units would enhance automobile

features completely.

Engine

Chassis

Music System

Brakes

Lighting SystemBattery

Sensors

oorsWindows

GaugesClimate Control

eters

Engine

BodyChassis

Music System

Brakes

Lighting SystemBattery

Sensors

DoorsWindows

Gauges

Climate Control

Meters





Introduction

CAN (Controller Area Network) is a serial communication technology used especially for reliable data exchange between electronic control units (ECUs) in the automobile.

Originally introduced by Bosch in 1983. Point to Point wiring is being replaced by one serial bus connecting all control

systems. Standardized by ISO and SAE.



CAN communication

Basic concepts



CAN network



CAN BUS COMMUNICATION PRINCIPLEData that are transmitted from any Node, contains MESSAGE labelled with IDENTIFIER, which is unique throughout the network

All other nodes receive the message and each performs an acceptance test on the identifier to determine if the message, and thus its content, is relevant to that particular node.

If the message is relevant, it will be processed; otherwise it is ignored

Allows integration of additional CAN nodes without requiring modification of the CAN network. The maximum number of nodes is not specified. Networks are limited by

electrical loading, up to 64 nodes is normal05/01/2023CAN Presentation | Sukruth Ramesh Babu




CAN bus logic



Vehicle Bus Protocol

Protocol Abbreviation Nature

CAN Controlled Area Network an inexpensive low-speed serial bus for interconnecting automotive components

D2B Domestic Digital Bus a high-speed multimedia interface

FlexRay - a general purpose high-speed protocol with safety-critical features

I²C Inter-Integrated Circuit for attaching low-speed peripherals

KWP 2000 Keyword Protocol 2000– a protocol for automotive diagnostic devices (runs either on a serial line or over CAN)

LIN Local Interconnect Network a very low cost in-vehicle sub-network

MOST Media Oriented Systems Transport a high-speed multimedia interface

SPI Serial Peripheral Interface for communication with slow peripheral devices, which are accessed infrequently


CAN Bus characteristics

Bus length / Bit rate tradeoff 1M bit/sec 40 meters (131 feet)

500K bit/sec 100 meters (328 feet) 250K bit/sec 200 meters (656 feet) 125K bit/sec 500 meters (1640 feet)

CAN Presentation | Sukruth Ramesh Babu 05/01/2023


CAN FRAMES

Data Frame – For transmitting user data Remote Frame – Used for requesting 'data frame' from any other CAN node Error Frame – To indicate errors detected during communicationOverload Frame-To introduce delay in the transmission

CAN FRAME TYPES



DATA FRAME



DATA FRAME (Standard format and Extended Format)



CAN Presentation | Sukruth Ramesh Babu

• The DLC (Data Length Code) communicates the number of payload bytes to the receivers

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REMOTE FRAME



Error Frame

Types of error: There are five types of error are there in CAN and are listed below. And in case any one of these error is observed the error frame is transmitted.

Bit error Stuff error CRC error Form error Acknowledgement error



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BUS ACCESS IN CAN NETWORK





PRIORITIZATION OF CAN MESSAGES



CAN data protection

Reliable data transmission. Because CAN is also used in very time and safety critical applications within

the motor vehicle, requirements for data integrity are extremely high.



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NRZ Coding



BIT STUFFING



Error detection: Bit monitoring : Compares the bit and the bus level

ACK Check : Checks for the dominant bit Stuff Check : Detection of sixth consecutive bit

Form Check : Compares the bit stream with message format

Cyclic Redundancy Check: Compares the bit stream with the generator polynomial



Error Confinement and Error states:

Active

Passive

Bus OFF REC/TEC > 127

REC/TEC < 128

TEC > 255

Reset or Configuration of 128x11 recessive bits

REC: Receiver Error Counter

TEC: Transmit Error Counter



Thank you !!


CAN (Controller Area Network)

Automotive