HD64F2149 Datasheet, PDF (584/1035 Pages) Renesas Technology Corp – Hitachi 16-Bit Single-Chip Microcomputer

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
KBE = 0
(KBBR reception
disabled)
KBFSEL = 0
KBIE = 1
(KCLK falling edge
interrupts enabled)
KCLK pin
No
fall detected?
Yes
KBF = 1
(interrupt generated)
Interrupt handling
Clear KBF
KCLK
(pin state)
KBF bit
Interrupt
generated
Cleared
by software
Interrupt
generated
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
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