We aim to develop an efficient OS for complex real time, power-critical, reactive systems implemented on advanced heterogeneous architectures. Event-driven OS, developed specifically to target reactive event-driven systems, is much more efficient than traditional general-purpose OS. TinyOS, an existing event-driven OS, offers some very attractive concepts, but is insufficient to fulfill the ambitious software management role demanded. To overcome the limitations of TinyOS, we proposed an event-driven hierarchical power management framework. The hierarchical structure enhances design scalability, supports concurrency in both the application domain and architecture and enables power control at various granularities. The software management framework implements a hybrid power control policy and has the ability to formally devise and implement an optimal power scheduling policy.