H8S2112R Datasheet, PDF (600/984 Pages) Renesas Technology Corp – 16-Bit Single-Chip Microcomputer H8S Family / H8S/2100 Series

Section 19 Keyboard Buffer Control Unit (PS2)
19.4.9 KCLK Fall Interrupt Operation
In this device, clearing the KBFSEL bit to 0 in KBCRH enables the KBF bit in KBCRH to be
used as a flag for the interrupt generated by the fall of KCLK input.
Figure 19.14 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 18.11. When the KBF bit is used as the KCLK input fall
interrupt flag, the automatic I/O inhibit function does not operate.
Figure 19.14 Example of KCLK Input Fall Interrupt Operation
Rev. 1.00 May 09, 2008 Page 574 of 954
REJ09B0462-0100