Keypad Matrix And Direct Keys With Two Rotary Encoders; Signals - Intel PXA27 Series Design Manual

Keypad Interface
18.5.3

Keypad Matrix and Direct Keys with Two Rotary Encoders

This example discusses one of many possible configurations when interfacing to the PXA27x
processor keypad controller. This specific configuration shows the keypad controller interfaced to a
4 x 4 matrix keypad of 16 keys, four direct keys and two rotary encoders.
The use of two rotary encoders limits the number of direct key signals (KP_DKINx) to four.
Therefore, it is possible to use the matrix keypad to add additional direct key switches if the full
matrix keypad is not used. This implementation takes advantage of the internal debounce logic for
addition direct keys and eliminates the requirement of pull-down resistors and external debounce
logic need to support additional direct keys.
18.5.3.1

Signals

The signal definitions do not change, just the signal usage. See
information.
II:18-10
Figure 18-4
®
Intel PXA27x Processor Family Design Guide
for detailed signal