NEC Figure 21-10. Flowchart of Generation from Non-Maskable Interrupt Request to Acknowledgment, TMIF4 : Watchdog timer interrupt request flag

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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 request
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 of Generation from Non-Maskable Interrupt Request to Acknowledgment
WDTM : Watchdog timer mode register
WDT : Watchdog timer
Figure 21-11. Non-Maskable Interrupt Request Acknowledge Timing
TMIF4 : Watchdog timer interrupt request flag
Instruction Instruction CPU Instruction
TMIF4
PSW and PC Save, Jump
to Interrupt Servicing
Interrupt Sevicing
Program
The interrupt request generated during this period is acknowledged at the timing of ↑.