UPD784938 Datasheet, PDF (548/733 Pages) NEC – 16-Bit Single-Chip Microcontrollers

CHAPTER 23 INTERRUPT FUNCTIONS
Figure 23-9. Non-Maskable Interrupt Request Acknowledgment Operations (2/2)
(c) When a watchdog timer interrupt request is generated during NMI service program execution (when the
NMI interrupt priority is higher (when PRC in the WDM = 0))
Main routine
NMI request
Watchdog
timer
interrupt
request
Watchdog timer interrupt held
pending since PRC = 0
Pending watchdog timer interrupt is processed
(d) When an NMI request is generated twice during NMI service program execution
Main routine
NMI request
NMI Held pending since NMI service
request program is being executed
NMI
Held pending since NMI service
request program is being executed
NMI request was generated more than
once, but is only acknowledged once
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Preliminary User’s Manual U13987EJ1V0UM00