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CHAPTER 21 INTERRUPT AND TEST FUNCTIONS
WDTM4=1
(with watchdog timer
mode selected)?
Overflow in WDT?
WDTM3=0
(with non-maskable
interrupt selected)?
Interrupt request generation
WDT interrupt servicing?
Interrupt control
register unaccessed?
Interrupt
service start
Interrupt request
held pending
Reset processing
Interval timer
Start
No
Yes
Yes
No
Yes
No
Yes
No
Yes
No
Figure 21-10. Flowchart from the Time a Non-maskable Interrupt Request Is Generated UntilIt Is ReceivedWDTM : Watchdog timer mode registerWDT : Watchdog timerFigure 21-11. Non-Maskable Interrupt Request Acknowledge TimingTMIF4: Watchdog Timer Interrupt Request Flag
Instruction Instruction CPU Processing
TMIF4
PSW and PC Save, Jump
to Interrupt Servicing
Interrupt Servicing
Program
Interrupt requests generated during this time are received
at the timing indicated by ↑.