MC908QT1 FREESCALE [Freescale Semiconductor, Inc], MC908QT1 Datasheet - Page 83

• Manufacturer Part Number: MC908QT1
• Description: Microcontrollers
• Manufacturer: FREESCALE [Freescale Semiconductor, Inc]

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:
9.7.1 Keyboard Status and Control Register
The keyboard status and control register (KBSCR):
Bits 7–4 — Not used
KEYF — Keyboard Flag Bit
ACKK — Keyboard Acknowledge Bit
IMASKK— Keyboard Interrupt Mask Bit
MODEK — Keyboard Triggering Sensitivity Bit
Freescale Semiconductor
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These read-only bits always read as 0s.
This read-only bit is set when a keyboard interrupt is pending on port A or auto wakeup. Reset clears
the KEYF 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.
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.
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 pending
0 = No keyboard interrupt pending
1 = Keyboard interrupt requests masked
0 = Keyboard interrupt requests not masked
1 = Keyboard interrupt requests on falling edges and low levels
0 = Keyboard interrupt requests on falling edges only
Keyboard interrupt status and control register (KBSCR)
Keyboard interrupt enable register (KBIER)
Flags keyboard interrupt requests
Acknowledges keyboard interrupt requests
Masks keyboard interrupt requests
Controls keyboard interrupt triggering sensitivity
Address: $001A
Reset:
Read:
Write:
Figure 9-3. Keyboard Status and Control Register (KBSCR)
Bit 7
0
0
= Unimplemented
MC68HC908QY/QT Family Data Sheet, Rev. 5
6
0
0
5
0
0
4
0
0
KEYF
3
0
ACKK
2
0
0
IMASKK
1
0
Input/Output Registers
MODEK
Bit 0
0
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