Multiple touch plane compatible interface circuit and method

摘要

A method of determining a type of touch plane operator input device comprises sensing the impedance across first and second terminals of a touch plane operator input device to distinguish the touch plane operator input device as being one of at least two different types of touch plane operator input devices. A method of processing an input from a touch plane operator input device comprises determining a first location of a first touch on the touch plane operator input device; determining a second location of a second touch on the touch plane operator input device; comparing the first and second locations to obtain an indication of an amount of difference between the first and second locations; and determining whether the indication of the amount of difference exceeds a predetermined amount. These steps are performed by discrete logic circuitry that provides an event notification to a microprocessor when the indication of the amount of difference exceeds the predetermined amount. An interface circuit for a touch plane operator input device comprises a digital signal processor that includes a data processing path along which data from a touch plane operator input device passes while being processed by the digital signal processor. The interface circuit is capable of processing data from first and second different types of touch plane operator input devices. The data path is a common data processing path that is the same for input data for both of the first and second types of touch plane operator input devices.