CHAPTER 10 INTERRUPT FUNCTIONS
User's Manual U11919EJ3V0UM00
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10.4 Interrupt Processing Operation
10.4.1 Non-maskable interrupt request acceptance operation
The non-maskable interrupt request is unconditionally accepted even when interrupts are disabled. It is not
subject to interrupt priority control and takes precedence over all other interrupts.
When the non-maskable interrupt request is acknowledged, PSW and PC are saved to the stack in that order,
the IE flag is reset to 0, the contents of the vector table are loaded to the PC, and then program execution branches.
Figure 10-8 shows the flowchart from non-maskable interrupt request generation to acceptance. Figure 10-9
shows the timing of non-maskable interrupt request acceptance. Figure 10-10 shows the acceptance operation if
multiple non-maskable interrupts are generated.
Caution
During a non-maskable interrupt service program execution, do not input another non-
maskable interrupt request; if it is input, the service program will be interrupted and the new
interrupt request will be acknowledged.
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