s908qc16g0cdte Freescale Semiconductor, Inc, s908qc16g0cdte Datasheet - Page 79

• Manufacturer Part Number: s908qc16g0cdte
• Description: M68hc08 Family Of 8-bit Microcontroller Units Mcus
• Manufacturer: Freescale Semiconductor, Inc

The KBI vector fetch or software clear and the return of all enabled keyboard interrupt pins to a deasserted
level may occur in any order.
Reset clears the keyboard interrupt request and the MODEK bit, clearing the interrupt request even if a
keyboard interrupt input stays asserted.
9.3.1.2 MODEK = 0
If the MODEK bit is clear, the keyboard interrupt inputs are edge sensitive. The KBIPx bit will determine
whether an edge sensitive pin detects rising or falling edges. A KBI vector fetch or software clear
immediately clears the KBI latch.
The keyboard flag bit (KEYF) in KBSCR can be read to check for pending interrupts. The KEYF bit is not
affected by IMASKK, which makes it useful in applications where polling is preferred.
Freescale Semiconductor
KBI0
KBIx
KBIP0
KBIPx
(SEE
AWUIREQ
Figure
4-1)
1
0
1
0
VECTOR FETCH
S
S
INTERNAL BUS
Setting a keyboard interrupt enable bit (KBIEx) forces the corresponding
keyboard interrupt pin to be an input, overriding the data direction register.
However, the data direction register bit must be a 0 for software to read the
pin.
DECODER
TO PULLUP/
PULLDOWN ENABLE
TO PULLUP/
PULLDOWN ENABLE
KBIE0
KBIEx
Figure 9-2. Keyboard Interrupt Block Diagram
RESET
ACKK
MC68HC08QY/QT Family Data Sheet, Rev. 2
MODEK
NOTE
V
DD
D
KBI LATCH
CK
CLR
Q
IMASKK
SYNCHRONIZER
Functional Description
KEYF
KEYBOARD
INTERRUPT
REQUEST
79