NEC NEC PD78081(A), User Manual

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CHAPTER 12 INTERRUPT FUNCTION
CHAPTER 12 INTERRUPT FUNCTION
12.1 Interrupt Function Types
The following three types of interrupt functions are used.
(1) Non-maskable interrupt
This interrupt is acknowledged unconditionally even in the interrupt disabled status. It does not undergo
interrupt priority control and is given top priority over all other interrupt requests.
It generates a standby release signal.
One of the non-maskable interrupts is the interrupt request from the Watchdog Timer.
(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 specify flag register (PR0L, PR0H, PR1L).
Multiple high priority interrupts can be applied to low priority interrupts. If two or more interrupts with the same
priority are simultaneously generated, each interrupts has a predetermined priority (see Table 12-1).
A standby release signal is generated.
Maskable interrupts include three external interrupt requests and eight internal interrupt requests.
(3) Software interrupt
This is a vectored interrupt that occurs when the BRK instruction is executed. It is acknowledged even in a
disabled state. The software interrupt does not undergo interrupt priority control.