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User’s Manual U15798EJ2V0UD
CHAPTER 19 INTERRUPT FUNCTIONS
19.1 Interrupt Function Types
The following three types of interrupt functions are used.
(1) Non-maskable interrupt
This interrupt is acknowledged even in an interrupt disabled state. It does not undergo priority control and is
given top priority over all other interrupt requests. However, a non-maskable interrupt is held pending during
servicing of another non-maskable interrupt.
A standby release signal is generated and HALT mode is released.
Only the interrupt request 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 registers (PR0L, PR0H, PR1L).
High priority interrupt nesting can be applied to low priority interrupts. If two or more interrupts with the same
priority are simultaneously generated, each interrupt has a predetermined priority (see
Table 19-1
).
A standby release signal is generated and the STOP and HALT modes are released.
Eight external interrupt requests and 16 internal interrupt requests are incorporated as maskable interrupts.
(3) Software interrupt
This is a vectored interrupt to be generated by executing the BRK instruction. It is acknowledged even in an
interrupt disabled state. The software interrupt does not undergo interrupt priority control.
19.2 Interrupt Sources and Configuration
A total of 26 interrupt sources exist among non-maskable, maskable, and software interrupts (see
Table 19-1
).
Remark
A non-maskable interrupt or maskable interrupt (internal) can be selected as the watchdog timer interrupt
(INTWDT).
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