 Introduction
kfz-tech.de/YC21
Yes, our books about the CAN bus are our bestsellers and we have long since responded to the first criticisms and brought out new editions. Nevertheless, we have the feeling that the
knowledge about the CAN bus from 2014 might not be sufficient for today's world.
So right at the start we apologize for using the term 'CAN bus' again, knowing full well that we will end up going far beyond that. Forgive us for these marketing reasons, but it is also difficult to
narrow down what we are planning.
There are two major topics that will dominate the further development of our cars: electromobility and software, if we will leave out experiments relating to cars, e.g. in the city. Based on this,
we do not want to broach the issue of the trend towards electric cars this time.
Everything related to software is so extensive that we need to focus at least a little here. Although, if we don't say the letters 'K' and 'I' in a hurry, we'll be out of the window as soon as we get to
the introduction, an absolute fashion trend, unbeatable as a term at the moment.
No, we will by no means base everything on it. Who knows how long this will continue, with every piece of software being classified as AI. But of course we won't be able to avoid autonomous
driving, although this time it will be seen networked and in the course of development.
If you are still rightly wondering what this is all about, here is a clear, albeit not very brief, answer.
What are we actually assuming about the CAN bus? Was saving cables really the main goal of its development? Of course not. It must be seen as a provisional end point in the installation of
more and more control units in cars.
Added to this was the ever-increasing role that suppliers played in the development and production of a car. Functions that had previously not even been thought of were suddenly possible.
Perhaps not ABS, that did exist, but ESP, for example.
Regarding the latter, there is the famous question of what electronics can do if, after a long straight, you suddenly turn 90° into another road at high speed. The answer: Of course, there is a
high probability that you will go off the road.
The crucial addition: But ESP can play a decisive role in how you leave the road. For example, it can possibly prevent a rollover. That would then be just one segment of an ever-increasing
effort to actively prevent accidents.
And later also reducing the consequences, for example when the hood is easily blown off at the side of the windshield to protect pedestrians who have been hit. And so the number of
suppliers and their control units grew ever larger.
In order to be able to cope better not only with the additional cables but also with the complex sensors, the CAN bus made it possible to use them multiple times - a tender first seedling of
networking, if you will.
You see, and here we come to a keyword that we can no longer avoid from now on, and will probably be mentioned more often in the future than artificial intelligence. A huge topic, then,
initially only perceived as a way of communicating with one another.
No, the first CAN buses didn't want to be open to the outside and even fearfully isolated themselves. So the CAN bus was initially not allowed into the engine compartment, which was difficult to protect. The task was
increasingly transferred to the LIN bus.
This had the advantage that no communication was possible from the slave to the master, and the master was located inside. So, by definition, you couldn't get into the system from outside. The slave could only answer
questions that the master asked it to a very limited extent.
A lot was already possible within the framework of the CAN bus or, one must say, the CAN buses. If the appropriate preparation was in place, control units or sensors could even be connected later without changing the
software.
Just think of the countless extras that are sold with a car. Theoretically, the software for the most expensive version could also be included in the cheapest vehicle at no great cost. You can see that this could easily push the
limits of the hardware.
Another huge topic today: How can hardware keep up with newer software versions when updating? Does it perhaps represent a limit to the ability to Over The Air update? That and the
consequences, more
on that later in this book.
| 
