
Keyboard Interrupt Module (KBI)
Data Sheet
MC68HC908QL Family
96
Keyboard Interrupt Module (KBI)
MOTOROLA
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
Address: $001A
Bit 7
654321
Bit 0
Read:
0000
KEYF
0
IMASKK
MODEK
Write:
ACKK
Reset:
00000000
= Unimplemented
Figure 9-4. Keyboard Status and Control Register (KBSCR)