
59
4.4
Interrupts
4.4.1
Interrupt Sources
Table 4.6 lists the types of interrupt exception handling sources (NMI, user break, IRQ, on-chip
supporting module).
Table 4.6
Interrupt Sources
Interrupt
Requesting Pin or Module
Number of Sources
NMINMI
pin (external input)
1
User break
User break controller
1
IRQ
IRQ0
–
IRQ7
pin (external input)
8
On-chip supporting
Direct Memory Access Controller
4
module
16-bit integrated timer pulse unit
15
Serial communication interface
8
A/D converter
1
Watchdog timer
1
Bus state controller
2
Each interrupt source has a different vector number and vector address offset value. See table 5.3,
Interrupt Exception Vectors and Rankings, in section 5, Interrupt Controller (INTC), for details on
vector numbers and vector table address offsets.
4.4.2
Interrupt Priority Rankings
Interrupt sources are assigned priorities. When multiple interrupts occur at the same time, the
interrupt controller (INTC) ascertains their priorities and starts exception handling based on its
findings. Priorities from 16–0 can be assigned, with 0 the lowest level and 16 the highest. NMI has
priority level 16 and cannot be masked. NMI is always accepted. The user break priority level is
15. The IRQ and on-chip supporting module interrupt priority levels can be set in interrupt priority
level registers A–E (IPRA–IPRE) as shown in table 4.7. Priority levels 0–15 can be set. See
section 5.3.1, Interrupt Priority Registers A-E (IPRA–IPRE), for details.
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