Datasheet

Section 17 Keyboard Buffer Controller
Rev. 4.00 Sep 27, 2006 page 580 of 1130
REJ09B0327-0400
17.3.8 KCLK Fall Interrupt Operation
In this device, clearing the KBFSEL bit to 0 in KBCRH enables the KBF bit in KBCRL to be used
as a flag for the interrupt generated by the fall of KCLK input.
Figure 17.13 shows the setting method and an example of operation.
Start
Set KBIOE
KBF = 1
(interrupt generated)
KBE = 0
(KBBR reception
disabled)
Interrupt handling
Clear KBF
KCLK pin
fall detected?
KBFSEL = 0
KBIE = 1
(KCLK falling edge
interrupts enabled)
Ye s
No
KCLK
(pin state)
KBF bit
Interrupt
generated
Interrupt
generated
Cleared
by software
Note: The KBF setting timing is the same as the timing of KBF setting and KCLK automatic I/O inhibit bit
generation in figure 17.11. When the KBF bit is used as the KCLK input fall interrupt flag, the
automatic I/O inhibit function does not operate.
Figure 17.13 Example of KCLK Input Fall Interrupt Operation