CHAPTER 14 INTERRUPT FUNCTIONS
Figure 14-9. Flow from Generation of Non-Maskable Interrupt Request to Acknowledgment
Start
WDTM4 = 1
No
(watchdog timer mode
is selected)
Interval timer
Yes
No
No
WDT
overflows
Yes
WDTM3 = 0
(non-maskable interrupt
is selected)
Reset processing
Yes
Interrupt request is generated
Interrupt servicing starts
WDTM: Watchdog timer mode register
WDT: Watchdog timer
Figure 14-10. Timing of Non-Maskable Interrupt Request Acknowledgment
Saving PSW and PC, and
jump to interrupt servicing
CPU processing
WDTIF
Instruction
Instruction
Interrupt servicing program
Figure 14-11. Non-Maskable Interrupt Request Acknowledgment
Main routine
First interrupt servicing
NMI request
(second)
NMI request
(first)
Second interrupt servicing
User’s Manual U15075EJ1V0UM00
273
NEC [ NEC ]
