Multiple port i2c hub

Abstract

A multiport device is configured to recognize each active segment on a bus, and to selectively propagate signals within the device depending upon whether the segment is active. Optimal signal propagation is achieved by invoking the control of the propagation of signals only after a first active-transition on the bus. Initial transitions are propagated unconditionally, to minimize propagation delay, and subsequent signal propagations are conditionally controlled, to avoid latch-up. A latch is associated with each port. The latch is set each time the port is actively driven by a device on that port. The latch is reset when all the devices are in the quiescent state, or when another port remains active after the currently active port becomes inactive. The state of each port's latch controls the propagation of internally generated signals to the port. If the latch is set, internally generated signals are not propagated to the port, thereby preventing latch-up. If the latch is not set, both internally generated signals and externally generated signals are propagated to the port, thereby minimizing propagation delays.