The partitioning of applications into hardware and software is an important issue in embedded systems, opening room for high level specifications as well as the exploration of different implementation strategies. This paper presents a software architecture to specify threads in hardware in the context of the Real Time Specification for Java (RTSJ) standard. There is a Java class that encapsulates hardware components, providing an abstraction layer to the application developer. Below this Java class, a wrapper hardware component provides a standard interface between RTSJ-based software components and the hardware that implements the thread behavior. This approach provides a high flexibility in choosing either a hardware or software implementation, allowing to postpone hardware/software partitioning to the very end of system development. The paper includes some quantitative data from an example containing hardware and software threads. While both implementations are compatible with the rest of the application from an interface point-of-view, they lead to very different timing and area results.