Interrupt Sources; Nmi Interrupts; User Break Interrupt; Irq Interrupts - Hitachi SH7032 Hardware Manual

5.2

Interrupt Sources

There are four types of interrupt sources: NMI, user break, IRQ, and on-chip supporting module
interrupts.
Interrupt rankings are expressed as priority levels (0–16), with 0 the lowest and 16 the highest. An
interrupt set to level 0 is masked.
5.2.1

NMI Interrupts

NMI is the highest-priority interrupt (level 16) and is always accepted. Input at the NMI pin is
edge-sensed. Either the rising or falling edge can be selected by setting the NMI edge select bit
(NMIE) in the interrupt control register (ICR). NMI interrupt exception handling sets the interrupt
mask level bits (I3–I0) in the status register (SR) to level 15.
5.2.2

User Break Interrupt

A user break interrupt occurs when a break condition is satisfied in the user break controller
(UBC). A user break interrupt has priority level 15. User break interrupt exception handling sets
the interrupt mask level bits (I3–I0) in the status register (SR) to level 15. For further details on the
user break interrupt, see section 6, User Break Controller (UBC).
5.2.3

IRQ Interrupts

IRQ interrupts are requested by input from pins IRQ0–IRQ7. IRQ sense select bits 0–7 (IRQ0S–
IRQ7S) in the interrupt control register (ICR) can select low-level sensing or falling-edge sensing
for each pin independently. Interrupt priority registers A and B (IPRA and IPRB) can select
priority levels from 0–15 for each pin. IRQ interrupt exception handling sets the interrupt mask
level bits (I3–I0) in the status register (SR) to the priority level value of the IRQ interrupt that was
accepted.
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