The availability of programmable hardware devices with high density of logic elements and the possibility of implementing CPUs (called softcores) using a fraction of the FPGA area offers additional flexibility for the implementation of embedded applications with real-time constraints. When implementing functions on such devices, designers can choose between hardware and software. Also, the designer can select the number of CPUs that must be created to best support the execution of the real-time software.

In this paper, we define a design optimization procedure for hard real-time systems, in which each functional block can be implemented in HW, using the logic elements available on the FPGA, or in SW, by means of a real-time task executed by a softcore. The optimizer allocates the functions and the softcores such that the HW implemented part is mapped within the area constraints and the software part is allocated so that schedulability can be guaranteed. When feasible solutions exist, the minimum utilization solution is computed.