Application modes and system startup

The OSEK Operating system gives a support for Application Modes. In real applications, an embedded system may execute different applications in a mutually exclusive way (for example, the normal operation, a factory test, and like). The application mode is a means to structure the software running in the system according to those different conditions and are a clean mechanism for development of totally separate systems. Once the operating system has been started, it is not allowed to change the application mode. Typically each application mode uses its own subset of tasks, ISRs, alarms and timing conditions, although if some kind of sharing between modes is possible.

The start up performance is another safety critical issue for embedded system in automotive applications since reset conditions may occur during normal operation (for example, a power-train application should be capable of rebooting the whole system in a few microseconds, because the system must safely control the spark on the engine cylinders). The system startup is completely left to the particular implementation, although if some hint is given on how design the boot-up sequence. In any case the standard suggest the avoidance of lengthy or complicated starting procedures.