M68HC08 datasheet(95/188 Pages) FREESCALE

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Keyboard/External Interrupt Module (KBI)

Functional Description

MC68HC908RF2 — Rev. 4.0

Data Sheet

MOTOROLA

Keyboard/External Interrupt Module (KBI)

Figure 7-2. IRQ Block Diagram

Interrupt signals on the IRQ pin are latched into the IRQ1 latch. Keyboard interrupts

are latched in the keyboard interrupt latch. An interrupt latch remains set until one

of these actions occurs:

•

Vector fetch — A vector fetch automatically generates an interrupt

acknowledge signal that clears IRQ1 latch and keyboard interrupt latch.

•

Software clear — Software can clear an interrupt latch by writing to the

appropriate acknowledge bit in the interrupt status and control register

(INTKBSCR). Writing a 1 to the ACKI bit clears the IRQ1 latch. Writing a 1

to the ACKK bit clears the keyboard interrupt latch.

•

Reset — A reset automatically clears both interrupt latches.

ACKI

IMASKI

CLR

IRQ1

HIGH

INTERRUPT

TO MODE

SELECT

LOGIC

IRQ1

LATCH

REQUEST

IRQ

VDD

MODEI

VOLTAGE

DETECT

SYNCHRO-

NIZER

IRQ1F

TO CPU FOR

BIL/BIH

INSTRUCTIONS

VECTOR

FETCH

DECODER

VDD

KEYBOARD

INTERRUPT

REQUEST

IRQ1/KEYBOARD

INTERRUPT

REQUEST

INTERNAL

PULLUP

DEVICE

RESET

Addr.

Bit 7

654321

Bit 0

$001A

IRQ and Keyboard Status

and Control Register

(INTKBSCR)

See page 101.

Read:

IRQ1F

IMASKI

MODEI

KEYF

IMASKK

MODEK

Write:

ACKI

ACKK

Reset:

00000000

$001B

Keyboard Interrupt Enable

See page 102.

Read:

KBIE6

KBIE5

KBIE4

KBIE3

KBIE2

KBIE1

Write:

Reset:

00000000

= Unimplemented

= Reserved

Figure 7-3. IRQ and Keyboard I/O Register Summary

Freescale Semiconductor, Inc.

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