This application note describes how to use a keypad input in a MicroConverter application, including configuring the MicroConverter to poll the keypad continuously or configuring the keypad interface in an interrupt driven system.
This document provides instructions for connecting a 16-way XY-Matrix hexadecimal keypad to the Analog Devices MicroConverter. It details two operational modes: continuous polling, where the device constantly checks for key presses, and an interrupt-driven system that triggers only upon input.
The guide includes specific circuit diagrams (Figure 3 and Figure 4) showing how to connect the keypad rows and columns to Port 2 of the MicroConverter. It also references assembly code files (KEYSPOLL.ASM and KEYSINT.ASM) for implementing these operations.
The system uses a 16-way XY-Matrix hexadecimal keypad with eight rear connections.
Columns X1 through X4 connect to port pins P2.4 through P2.7, while rows Y1 through Y4 connect to pins P2.0 through P2.3.
A negative-going edge produced by the external logic circuitry for each key press triggers the INT1 interrupt service routine.