7477 datasheet(244/354 Pages) RENESAS

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2-9

7470/7471/7477/7478 GROUP USER’S MANUAL

APPLICATION

2.2 Interrupts

7470

7471

7477

7478

2.2.3 Application example

(1)External event detection by CNTR

To detect a rising edge or a falling edge of the level of an input pin by using a pin other than the

INT0 pin and the INT1 pin, it is possible to use the CNTR pin. Examples of use are shown below.

q When the CNTR0 pin is used

CNTR interrupt+1

1 Set the edge polarity selection register.

• Select a CNTR0 edge polarity.

• Select CNTR0 as an interrupt source.

2 Clear the CNTR interrupt request bit to “0.”

3 Execute the NOP instruction.

4 Set the CNTR interrupt enable bit to “1.”

q When the CNTR1 pin is used

Timer 3 interrupt+1,+2

1 Stop the count operation of timer 3.

2 Select CNTR1 as a count source of timer 3.

3 Select a CNTR1 edge polarity by the Edge polarity selection register.

4 Set timer 3 to “0.”

5 Clear the timer 3 interrupt request bit to “0.”

6 Set the timer 3 interrupt enable bit to “1.”

7 Start the count operation of timer 3.

+1: It is possible to use the CNTR0 pin for a timer interrupt and the CNTR1 pin for a CNTR interrupt.

+2: It is possible to use timer 4 as an interrupt source.

2.2.4 Notes on use

2 For notes on use, refer to “1.11 Interrupts.”

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7477 Datasheet(PDF) 244 Page - Renesas Technology Corp