Serial communication technique

Abstract

Information can be communicated back from a receiver to a transmitter over a serial link designed for communication to be essentially only in one direction without requiring a separate feedback path with an extra wire. This is achieved by changing at least one characteristic of the receiver input. For example, the receiver input impedance, the receiver input voltage, or both, may be altered. The change in a characteristic of the receiver input can be detected by an appropriately designed transmitter, and such detection can be used to trigger a change in the behavior of the transmitter. Advantageously, only simple alterations are required in conventional serial link circuits to provide a low bandwidth reverse communication path over the same wires. Such a change in a receiver input characteristic can also be employed to inform a transmitter of the existence of a receiver that is on a card that is hot-plugged into system.

Dependencies are inferred from the claim text.