MC908QT4MPE datasheet(83/184 Pages) FREESCALE

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Input/Output Registers

MC68HC908QY/QT Family Data Sheet, Rev. 5

Freescale Semiconductor

To protect the latch during the break state, write a 0 to the BCFE bit. With BCFE at 0 (its default state),

writing to the keyboard acknowledge bit (ACKK) in the keyboard status and control register during the

break state has no effect.

9.7 Input/Output Registers

The following I/O registers control and monitor operation of the keyboard interrupt module:

•

Keyboard interrupt status and control register (KBSCR)

•

Keyboard interrupt enable register (KBIER)

9.7.1 Keyboard Status and Control Register

The keyboard status and control register (KBSCR):

•

Flags keyboard interrupt requests

•

Acknowledges keyboard interrupt requests

•

Masks keyboard interrupt requests

•

Controls keyboard interrupt triggering sensitivity

Bits 7–4 — Not used

These read-only bits always read as 0s.

KEYF — Keyboard Flag Bit

This read-only bit is set when a keyboard interrupt is pending on port A or auto wakeup. Reset clears

the KEYF bit.

1 = Keyboard interrupt pending

0 = No keyboard interrupt pending

ACKK — Keyboard Acknowledge Bit

Writing a 1 to this write-only bit clears the keyboard interrupt request on port A and auto wakeup logic.

ACKK always reads as 0. Reset clears ACKK.

IMASKK— Keyboard Interrupt Mask Bit

Writing a 1 to this read/write bit prevents the output of the keyboard interrupt mask from generating

interrupt requests on port A or auto wakeup. Reset clears the IMASKK bit.

1 = Keyboard interrupt requests masked

0 = Keyboard interrupt requests not masked

MODEK — Keyboard Triggering Sensitivity Bit

This read/write bit controls the triggering sensitivity of the keyboard interrupt pins on port A and auto

wakeup. Reset clears MODEK.

1 = Keyboard interrupt requests on falling edges and low levels

0 = Keyboard interrupt requests on falling edges only

Address: $001A

Bit 7

654321

Bit 0

Read:

0000

KEYF

IMASKK

MODEK

Write:

ACKK

Reset:

00000000

= Unimplemented

Figure 9-3. Keyboard Status and Control Register (KBSCR)

MC908QT4MPE Datasheet(PDF) 83 Page - Freescale Semiconductor, Inc

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