Passive user input attachment engaging compressible conductive elements and method for using the same

Abstract

A user input attachment () is configured to selectively attach to an electronic device () such as a mobile telephone. The electronic device () includes a plurality of electrode nodes (), which can be configured separately from each other across one or more surfaces of the electronic device (). A controller (), which is operable with the plurality of electrode nodes (), is configured to sense current flowing through (or voltage across) the electrode nodes (). The sensed voltage or current establishes an engagement signature () dependent upon pressure from compressible conductive elements () against electrode nodes () from the user input attachment (), and where included, one or more protuberances (). The controller () is configured to identify the user input attachment () from the engagement signature (), and to detect user input by detecting changes from the engagement signature () due to variations in the current () in, or voltage across, each of the electrode nodes () caused by user manipulation of the user input attachment ().