NEC PD78F9488 - Manual (Page 302)

CHAPTER 16 INTERRUPT FUNCTIONS
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User’s Manual U15331EJ4V1UD
Figure 16-10. Flow from Generation of Non-Maskable Interrupt Request to Acknowledgment
Start
WDTM4 = 1
(watchdog timer mode
is selected)
Interval timer
No
WDT
overflows
No
Yes
Reset processing
No
Yes
Yes
Interrupt request is generated
Interrupt servicing starts
WDTM3 = 0
(non-maskable interrupt
is selected)
WDTM: Watchdog timer mode register
WDT: Watchdog timer
Figure 16-11. Timing of Non-Maskable Interrupt Request Acknowledgment
Instruction Instruction
Saving PSW and PC, and
jump to interrupt servicing
Interrupt servicing program CPU processing
WDTIF
Figure 16-12. Non-Maskable Interrupt Request Acknowledgment
Second interrupt servicing
First interrupt servicing
NMI request
(second)
NMI request
(first)
Main routine