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

Part A

CAN: From Concept to Reality

Let us be clear that we are talking about CAN (controller area network).¹ Yet another new protocol and system! True, but we must realize that it is not an easy matter to bring everybody into agreement, especially when everyone has his own objectives and specific technical requirements, and that major markets are sufficient to justify and optimize every concept (which clearly means reducing the cost!). So here is a new serial protocol to be added to the burgeoning family of local area networks (LANs).

As described by the ISO (International Organization for Standardization) standards, CAN is a ‘serial communication protocol which efficiently supports the distribution of commands in real time with a high security level. Its preferred fields generally relate to high bit rate, high transmission reliability network applications operating on a low-cost multiplexed cable principle’. You have been warned…

In this part of the book, I will describe the CAN protocol and some of its main applications.

I should point out that this concept was not developed overnight, but is the fruit of lengthy research and experimentation. Clearly, I could move straight on to a description of its operation, but I think this would deprive us of a depth of knowledge of the problems relating to buses used in local networks.

Indeed, some ideas commonly seem to spring up ‘naturally’, but often the major break-throughs in our thinking are due to sequences of apparently unrelated ...