AUTOSAR for dummies - #1

Autosar is one of the most famous buzz word in the automotive field for quite some time now. I have found that most beginners to AUTOSAR and even sometimes the experienced struggle to understand what it is, why it was created and what can be done with it. I will try to answer these questions in as simple terms as possible in this article series.

If you are from general embedded/other SW background, the automotive SW development may look like a communist country.No one on the outside knows what's happening there, but it somehow works fine. They have custom controllers, custom compilers, custom development methods, test strategies etc..We have this scenario because of multiple reasons.first of them is that unlike most embedded systems the automotive systems have to be really quick. The precision should be in terms of microseconds in some cases, otherwise, the safety of the driver and occupants are at risk.The control units also have to endure a very harsh environment e.g on the temperature scale of Siberia to lava .in addition to temperature, pressure and electromagnetic interference should also be considered. There are a lot of other reasons as well

This led to major side effects like non-modularity, non-scalability, non-reusability, etc..Let me given an example, you have an HP PC with Linux pre-installed but you decided to get windows and install iTunes or chrome or any other competitor SW. A similar thing is not possible or very costly in the automotive sector. They cannot switch to a different operating system, because Os in this field are tightly coupled to the HW and application SW and it is proprietary. The entire SW should be provided by the ECU supplier only. Usually, one company will not be the best in the HW, drivers and multiple applications. As a customer, the OEMs wanted to pick the vendors for HW or Driver SW or different applications separately for quality or cost or performance reasons.

Wrt scalability, for example, if a car is upgrading from a 4 cylinder engine to 6 cylinders (even without any other changes), it was not possible without a significant coding effort to upgrade the SW in most cases. Ideally, this should be just some configuration setting change.

Wrt non-reusability, if we are changing the micro-controller in an ECU, this would result in significant SW changes in drivers, Os and even in some parts of the application. This is the same case with change of compilers

This really worried the car manufacturers and ECU suppliers. So in July 2003 BMW, Bosch, Continental, Daimler, Chrysler, Siemens VDO and Volkswagen decided to put an end to it by forming the AUTOSAR consortium. Later more members joined them. Between 2004-06, the first AUTOSAR standard was released and now in 2019, we have the 4.4,0 classic version and an adaptive version.

So..What is it ?????????????????????

To give a basic technical definition, Autosar provides an open SW architecture standard, guidelines/rules on application interfaces, acceptance tests and provides methodology for autosar based development. 

Autosar SW Architecture:

In the PC world pre-1981 era, All HW parts and OS were developed and manufactured by a single company. That meant you cannot choose your graphics card vendor, OS or a lot of other things. Everything changed when IBM introduced its 5150 PC, it had an intel controller and a DOS operating system. This was the beginning of a revolution in the PC industry. So how did they do it? They did it by developing modular and open HW architecture. They made the HW such that other devices could be fitted in and made the HW specification open so that anyone in the world could create a spare part.

Autosar SW architecture is also a similar concept. It gives an open architecture and SW specification. A house plan doesn't have any brick or cement or anything in it, but with the same plan any number of persons can build units of the house with materials from any vendors and it will eventually work fine. Similarly, AUTOSAR architecture gives a plan on how to create each SW part by different persons but eventually would work fine.

AUTOSAR also considers all the factors like scalability, reusability, modularity etc..So how exactly this planning is done, how these things are taken into consideration, we will discuss further in Autosar-for-dummies-part-2