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2.2 Interrupts

2-16

Rev.2.01

Feb 07, 2005

4501 Group

APPLICATION

REJ09B0192-0201

2.2.3 Interrupt application examples

(1)

INT interrupt

The INT pin is used for external 0 interrupt, of which valid waveforms can be chosen, which can

recognize the change of both edges (“H”

→“L” or “L”→“H”).

Outline: An external 0 interrupt can be used by dealing with the change of edge (“H”

→“L” or

“L”

→“H”) in both directions as a trigger.

Specifications: An interrupt occurs by the change of an external signals edge (“H”

→“L” or “L”→“H”).

Figure 2.2.1 shows an operation example of an external 0 interrupt, and Figure 2.2.2 shows a setting

example of an external 0 interrupt.

(2)

Timer 1 interrupt

Constant period interrupts by a setting value to timer 1 can be used.

Outline: The constant period interrupts by the timer 1 underflow signal can be used.

Specifications: Prescaler and timer 1 divide the system clock frequency f(XIN) = 4.0 MHz, and the

timer 1 interrupt occurs every 1 ms.

Figure 2.2.3 shows a setting example of the timer 1 constant period interrupt.

(3)

Timer 2 interrupt

Constant period interrupts by a setting value to timer 2 can be used.

Outline: The constant period interrupts by the timer 2 underflow signal can be used.

Specifications: Timer 2 and prescaler divide the system clock frequency (= 4.0 MHz), and the timer

2 interrupt occurs every about 1 ms.

Figure 2.2.4 shows a setting example of the timer 2 constant period interrupt.

Fig. 2.2.1 INT interrupt operation example

P13/INT

“H”

“L”

An interrupt occurs after the valid waveform “falling” is detected.

An interrupt occurs after the valid waveform “rising” is detected.

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