HD64F2145 datasheet(135/829 Pages) RENESAS

135 / 829 page

Rev. 2.0, 08/02, page 95 of 788

NMI Interrupt: NMI is the highest-priority interrupt, and is always accepted by the CPU

regardless of the interrupt control mode or the status of the CPU interrupt mask bits. The NMIEG

bit in SYSCR can be used to select whether an interrupt is requested at a rising edge or a falling

edge on the NMI pin.

IRQ7 to IRQ0 Interrupts: Interrupts IRQ7 to IRQ0 are requested by an input signal at pins

,54:

,543. Interrupts IRQ7 to IRQ0 have the following features:

• The interrupt exception handling for interrupt requests IRQ7 to IRQ0 can be started at an

independent vector address.

• Using ISCR, it is possible to select whether an interrupt is generated by a low level, falling

edge, rising edge, or both edges, at pins

,54: to ,543.

• Enabling or disabling of interrupt requests IRQ7 to IRQ0 can be selected with IER.

• Interrupt control levels can be specified by the ICR settings.

• The status of interrupt requests IRQ7 to IRQ0 is indicated in ISR. ISR flags can be cleared to 0

by software.

The detection of IRQ7 to IRQ0 interrupts does not depend on whether the relevant pin has been

set for input or output. However, when a pin is used as an external interrupt input pin, do not clear

the corresponding DDR to 0 to use the pin as an I/O pin for another function.

A block diagram of interrupts IRQ7 to IRQ0 is shown in figure 5.3.

IRQn interrupt

request

IRQnE

IRQnF

Clear signal

Edge/level

detection circuit

IRQnSCA, IRQnSCB

input

n = 7 to 0

Figure 5.3 Block Diagram of Interrupts IRQ7 to IRQ0

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