Network-on-Chip (NoC) has been proposed to overcome the complex on-chip communication problem of SoC (System-on-Chip) design in deep submicron. A complete NoC design contains exploration on both hardware and software architectures. The hardware architecture includes the selection of PEs (Processing Elements) with multiple types and their topology. The software architecture contains the allocation of tasks to PEs, scheduling of tasks and their communications. To find the best hardware design for the target tasks, both hardware and software architectures need to be considered simultaneously. Previous works on NoC design have concentrated on solving for only one or two design parameters at a time. In this paper, we propose a hardware-software co-synthesis algorithm for a heterogeneous NoC architecture. The design goal is to minimize energy consumption while meeting the real-time requirements commonly seen in the embedded applications.