Method and apparatus for detecting the insertion or removal of expansion cards using capacitive sensing

Abstract

A detection system for detecting the insertion or removal of expansion cards having a standard edge connector using one or more capacitive plates coupled to corresponding variable frequency oscillators. The capacitive plates are preferably mounted on an internal layer of the expansion card and preferably aligned with corresponding pins of the edge connector for establishing capacitive loading with respect to the corresponding pins. The frequency of the oscillators change with changes in the capacitive loading of the corresponding plates. The detection circuitry includes a processor which continuously monitors the frequency of the oscillators to thereby detect movement of the expansion card, and preferably includes a control and isolation circuit which electrically isolates the power and data pins during insertion and/or removal as controlled by the processor. The detection circuitry may be mounted to either on the expansion card or the planar of the computer system. If mounted on the expansion card, the power and data pins are in a tristated condition while the option card is removed from the planar. The processor detects that the expansion card is being inserted or removed when the frequency of one or both oscillators is at a predetermined frequency or shifts by a predetermined amount.

Dependencies are inferred from the claim text.