OSEK/VDX-operating systems for automotive applications

The complexity of electronic control units (ECU) in automotive applications increased dramatically over the past years. New functional requirements to control direct injection engines or adaptive cruise control for example introduce additional software algorithms. Furthermore, stricter regulations for the exhaust system and on-board diagnosis contribute to the fast growing code sizes. Next generation engine management systems include programs of more than 500 KBytes in size which run on 32 bit processors. For the first time floating point units will be used to perform computations with physical values directly, rather than transforming them to a hexadecimal representation. In order to run in pace with the physical process to be controlled, the ECU software has to meet stringent real-time constraints. Functions like injection and ignition require a highly accurate timing to guarantee fuel efficient operation. Moreover, knock-control and misfire-detection have to work reliably to prevent severe damages of the engine. Control units for braking and steering systems are directly linked to the passengers security and are thus classified as safety critical. Because real-time operating systems (OS) offer powerful means to handle complex functions under real-time conditions they are more and more introduced in automotive ECUs. The complexity of automotive applications varies a lot from simple control functions in the field of body electronics to high-end applications in the powertrain. Since conventional real-time operating systems are not able to fulfill the implied requirements in terms of runtime performance and memory consumption a lot of in-house solutions emerged in various companies. The wish to save development time by reusing existing components and the need of porting software between different ECUs even from different suppliers led to the OSEK/VDX standardization of an automotive real-time OS. Software sharing, i.e. the distributed development of ECU-software at different partner companies will also benefit from the introduction of a standardized OS.