Evaluating the Use of an RTOS to Reduce a Vehicle's Bill of Materials and Ensure Timing Correctness 2002-01-2212
On the face of it, the idea that software alone can reduce a vehicle's total bill of materials seems difficult to credit. However, when one examines the idea in detail, it becomes more plausible: according to analyst group Gartner Dataquest, 30% of the cost of constructing a new vehicle is in its electronic systems. A significant proportion of these electronic systems are electronic control units (ECUs) based around a microcontroller that contains an increasingly large amount of software. How the software is implemented on the microcontroller will has two key effects on ECU unit cost:
Software that leads to larger RAM requirements will typically increase the cost, particularly if the design results in a multi-chip implementation rather than a single chip implementation.
Software that demands higher performance from the microcontroller will typically increase the cost
The software design costs also have an effect on ECU cost, but this is amortized over the total production life of the ECU, and is low in comparison to hardware costs.
In this paper we shall show how the selection of an appropriate real-time operating system (RTOS) can lead to reductions in the performance requirements for a microcontroller in an ECU while maintaining low memory requirements, and consequently to a vehicle's overall bill of materials. Use of appropriate timing analysis technologies in conjunction with an RTOS that is capable of being analyzed can also assist in achieving cost reductions while improving the reliability of the application. This also will be discussed.
This paper assumes that any RTOS being selected will certified to comply with the OSEK/VDX OS standard[OSEK00], as such RTOSs offer many advantages to ECU developer over an RTOS with a proprietary interface. Furthermore, vehicle manufacturers are increasingly demanding ECU manufacturers use OSEK-compliant solutions.