MC68HC908QY4CDW Datasheet, PDF (83/184 Pages) Freescale Semiconductor, Inc – Microcontrollers

Input/Output Registers
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
Address: $001A
Bit 7
6
5
4
3
2
1
Bit 0
Read: 0
0
0
0
KEYF
0
IMASKK MODEK
Write:
ACKK
Reset: 0
0
0
0
0
0
0
0
= Unimplemented
Figure 9-3. Keyboard Status and Control Register (KBSCR)
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
MC68HC908QY/QT Family Data Sheet, Rev. 6
Freescale Semiconductor
83