AT90SCR100 datasheet(329/433 Pages) ATMEL

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TPR0327AY–SMS–30Jan09

AT90SCR100

23. Keyboard Interface

23.1

Features

• Allows connection of a 8x8 matrix keyboard

• Based on 8 inputs pins and 8 outputs specific pins

• Supports slow edge pads to avoid abusive EMC generation (on outputs pads only)

• Specific Keyboard pins only available in Full Pin Count package. See “Pin List Configuration” on

page 5.

• Allows chip wake-up on key pressed event

23.2

General Description

23.2.1

Overview

The keyboard interfaces with the AVR core through 3 registers: KBLS, the Keyboard Level

Selection register (page 332), KBE, The Keyboard interrupt Enable register (page 331), and

KBF, the Keyboard Flag register (page 330).

23.2.2

Interrupt

The keyboard inputs are considered as 8 independant interrupt sources sharing the same inter-

rupt vector. An interrupt enable bit allows global enable or disable of the keyboard interrupt (see

Figure 23-1). As detailed in Figure 23-2 each keyboard input can detect a programmable level

according to KBLS.x bit value. Level detection is then reported in interrupt flags KBFR.x that can

be masked by software using KBER.x bits.

The KBFR.x flags are set by hardware when an active level is on input PAx.

The KBFR register is reset by writing any data inside the KBFR.

Figure 23-1.

Keyboard Interface Block Diagram

You can choose to create a Keyboard interface only by using Pin Change Man-

agement.This module’s purpose is to ease the creation of little Pinpads.

Note

Input Circuitry

KbIN 0

KbIN 1

KbIN 2

KbIN 3

KbIN 4

PA0:

PA1:

PA2:

PA3:

PA4:

Input Circuitry

KbIN 5

PA5:

Input Circuitry

KbIN 6

PA6:

Input Circuitry

KbIN 7

PA7:

Global IT bit

Keyboard IT

Keyboard interface

Interrupt request

AT90SCR100 Datasheet(PDF) 329 Page - ATMEL Corporation

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