Embedded control systems have to be functionally correct, stable, and have to fulfil real-time constraints. The presented integrated approach of embedded software development supports the developer to meet design decisions in a system context using simulations at the system level and the task level of modelling. At the system level, first the behaviour of the digital controller model is specified. Secondly, the developer explores at the task level various alternatives of task scheduling policies and hardware/software architectures using simulations based on task models and virtual prototype models of the hardware. Estimated delays and scheduling times are back-annotated to the system level model. There the annotations are used to correct digital control algorithm parameters that the embedded system remains functionally correct and stable.