In this paper, we present a modular co-synthesis framework called CHARMED that solves the problem of hardware-software co-synthesis of periodic, multi-mode, distributed, embedded systems. In this framework we perform the synthesis under several constraints while optimizing for a set of objectives. We allow the designer to fully control the performance evaluation process, constraint parameters, and optimization goals. Once the synthesis is performed, we provide the designer a non-dominated set (Pareto front) of implementations on streamlined architectures that are in general heterogeneous and distributed. We also employ two different techniques, namely clustering and parallelization, to reduce the complexity of the solution space and expedite the search. The experimental results demonstrate the effectiveness of the CHARMED framework in computing efficient co-synthesis solutions within a reasonable amount of time.