Multiplexed Networks for Embedded Systems: CAN, LIN, FlexRay, Safe-by-Wire...

2

CAN: Its Protocol, Its Properties, Its Novel Features

In view of the intrinsic power of the CAN (controller area network) protocol and its different possibilities and varied implementations, I have decided to spread its description over several chapters. The key to this presentation is the way I have chosen to divide it.

The description of CAN consists of several parts, which are carefully presented so that they are easier to read and understand than the official documents, which can sometimes be baffling.

This chapter is purely concerned with the protocol, including

• the definition of the protocol,
• the main principles,
• the error processing,
• the rest of the frame,
• CAN 2.0B – description.

Chapters 3 and 4 are entirely devoted to what is generally called the ‘physical layer’ and its implementation in a medium. Chapter 3 will then give you all the necessary information about the bit structure, synchronization, the medium and the connection to the medium and the problems of propagation. Finally, in Chapter 4, I will discuss the large number of implementations of the physical layer in different media, such as copper wire, optical fibre, current power lines (CPL), etc.

2.1 Definitions of the CAN Protocol: ‘ISO 11898-1’

Let us start by describing and making a few simple comments on the original document issued by Bosch and then reproduced, with minor changes, in ISO 11898-1.

In this document, with the aim of ensuring transparency of the product and greater flexibility of implementation, ...