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4501_M Datasheet, PDF (133/212 Pages) Renesas Technology Corp – 4-BIT CISC SINGLE-CHIP MICROCOMPUTER 4500 SERIES | |||
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4501 Group
APPLICATION
2.2 Interrupts
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 (âHâââLâ or âLâââHâ).
Outline: An external 0 interrupt can be used by dealing with the change of edge (âHâââLâ or
âLâââHâ) in both directions as a trigger.
Specifications: An interrupt occurs by the change of an external signals edge (âHâââLâ or âLâââHâ).
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.
âHâ
P13/INT
âLâ
âHâ
P13/INT
âLâ
An interrupt occurs after the valid waveform âfallingâ is detected.
An interrupt occurs after the valid waveform ârisingâ is detected.
Fig. 2.2.1 INT interrupt operation example
Rev.2.01 Feb 07, 2005
REJ09B0192-0201
2-16
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