In this paper, the problem of automatically mapping large-grain dataflow programs onto heterogeneous hardware/softwarearchitectures is treated. Starting with a given hardware/softwarepartition, interfaces are automatically inserted into the specification to account for communication, inparticular across hardware/software boundaries. Depending on the target architecture, the interfaces are refined according to given communication constraints (bus protocols, memory mapping, interrupts, DMA, etc.). An objectoriented approach is presented that enables an easy migration (retargeting) of typical communication primitives to othertarget architectures.