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DRIVING AN ANALOG KEYBOARD WITH THE ST7 ADC

Figure 3. Flowchart: conversion process

4 ANALOG KEYBOARD

4.1 PRINCIPLE

The purpose is to recognize a key when pressed. In an analog keyboard each key is associ-

ated with a voltage. The description of an analog keyboard is given by Figure 4.

Figure 4. Hardware description of a keyboard with 16 keys

EOC = 1 ?

Conversion Process

KBD_init

read ADCDRL

no

yes

read ADCDRH

(Keyboard Value)

key 0

key 1

key 14

key 15

with

Σ