Datasheet

Section 18 Keyboard Buffer Control Unit (PS2)

Rev. 3.00 Sep. 28, 2009 Page 582 of 910

REJ09B0350-0300

18.4.9 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 18.14 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

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 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 18.14 Example of KCLK Input Fall Interrupt Operation