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.
