Method of detecting a source strobe event using change detection

Abstract

A hub based computer system having a central hub that communicates with a plurality of satellite devices over respective link buses. Each link bus is substantially the same and adheres to a predefined link bus protocol. The link bus protocol establishes a method in which data receiving circuitry of a target device can be put into a known state during a final stage of a source strobe event such as e.g., a data transfer. Once in the known state, the source strobes are stopped on the link bus. The target device uses internal logic clocked by a system clock rather than the source strobe to continuously sample the state of the receiving circuitry to see if the state has deviated from the known state. A change detect circuit determines if the receiving circuitry has deviated from the known state and if so, detects a new source strobe event. The change detect circuit detects the new event in the less stringent clock domain, which allows greater control of the skew and asymmetry of the source strobe. This allows the system to achieve substantially higher data transfer rates than conventional source strobe systems.