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User’s Manual U15104EJ2V0UD
CHAPTER 12 INTERRUPT FUNCTIONS
12.1 Interrupt Function Types
The following three types of interrupt functions are used.
(1) Non-maskable interrupts
This type of interrupt is acknowledged unconditionally even if interrupts are disabled. It does not undergo
interrupt priority control and is given top priority over all other interrupt requests.
It generates a standby release signal.
One interrupt source from the watchdog timer is incorporated as a non-maskable interrupt.
(2) Maskable interrupts
These interrupts undergo mask control. Maskable interrupts can be divided into a high interrupt priority group
and a low interrupt priority group by setting the priority specification flag register (PR).
Multiple interrupt servicing is possible if a high-priority interrupt is generated while a low-priority interrupt is
being serviced. If two or more interrupts with the same priority are simultaneously generated, each interrupt
has a predetermined priority (refer to Table 12-1).
A standby release signal is generated.
Maskable interrupts are provided for each product as follows.
•
µ
PD178053, 178054, 178F054 Internal: 11, external: 5
(3) Software interrupt
This is a vectored interrupt generated by executing the BRK instruction. It is acknowledged even in an interrupt-
disabled state. The software interrupt does not undergo interrupt priority control.
12.2 Interrupt Sources and Configuration
The
µ
PD178053, 178054, and 178F054 have a total of 17 sources (non-maskable interrupt, maskable interrupt,
software interrupt) (refer to Table 12-1).
Remark
Either a non-maskable interrupt or a maskable interrupt (internal) can be selected for the watchdog timer
interrupt source (INTWDT).