HD6473887 Datasheet, PDF (96/523 Pages) Renesas Technology Corp – Hitachi Single-Chip Microcomputer

3.3.5 Interrupt Operations
Interrupts are controlled by an interrupt controller. Figure 3-2 shows a block diagram of the
interrupt controller. Figure 3-3 shows the flow up to interrupt acceptance.
Interrupt controller
External or
internal
interrupts
Interrupt
request
External
interrupts or
internal
interrupt
enable
signals
I CCR (CPU)
Figure 3-2 Block Diagram of Interrupt Controller
Interrupt operation is described as follows.
• When an interrupt condition is met while the interrupt enable register bit is set to 1, an
interrupt request signal is sent to the interrupt controller.
• When the interrupt controller receives an interrupt request, it sets the interrupt request flag.
• From among the interrupts with interrupt request flags set to 1, the interrupt controller selects
the interrupt request with the highest priority and holds the others pending. (Refer to table 3-2
for a list of interrupt priorities.)
• The interrupt controller checks the I bit of CCR. If the I bit is 0, the selected interrupt request
is accepted; if the I bit is 1, the interrupt request is held pending.
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