uPD789871 Subseries 8-Bit Single-Chip Microcontrollers PUM
uPD789871 Subseries 8-Bit Single-Chip Microcontrollers PUM
uPD789871 Subseries 8-Bit Single-Chip Microcontrollers PUM
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CHAPTER 12 INTERRUPT FUNCTIONS<br />
Figure 12-6. Flowchart from Non-Maskable Interrupt Request Generation to Acknowledgement<br />
CPU processing<br />
WDTIF<br />
NMI request<br />
(first)<br />
Start<br />
WDTM4 = 1<br />
(watchdog timer mode<br />
is selected)<br />
Yes<br />
WDT<br />
overflows<br />
Yes<br />
WDTM3 = 0<br />
(non-maskable interrupt<br />
is selected)<br />
Yes<br />
Interrupt request is generated<br />
Interrupt processing is started<br />
WDTM: Watchdog timer mode register<br />
WDT: Watchdog timer<br />
Interval timer<br />
Figure 12-7. Timing of Non-Maskable Interrupt Request Acknowledgement<br />
Figure 12-8. Acknowledging Non-Maskable Interrupt Request<br />
No<br />
No<br />
No<br />
Instruction Instruction<br />
Main routine<br />
NMI request<br />
(second)<br />
Reset processing<br />
First interrupt processing<br />
Save PSW and PC, and<br />
jump to interrupt processing<br />
Interrupt processing<br />
program<br />
Second interrupt processing<br />
Preliminary User’s Manual U14938EJ1V0UM 129
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