Adaptive communication interface

Embodiments of the disclosed subject matter include a communication interface and protocol for allowing communication between devices, circuits, integrated circuits, and other electronic components having, for example, different communication capacities or clock domains. The interface supports communication between any components having any difference in capacity and over any distance. The interface utilizes request and acknowledge phases and signals and an initiator-target relationship between components that allow each side to throttle the communication rate to an accepted level for each component or achieve a desired bit error rate. Other devices, methods, and interfaces are disclosed.