Single-Chip Microcontrollers User's Manual

514

CHAPTER 22 INTERRUPT FUNCTIONS

Figure 22-10. Flowchart from Non-Maskable Interrupt Generation to Acknowledge

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

Interrupt

service start

Interrupt request

held pending

Reset processing

Interval timer

Start

Yes

WDTM : Watchdog timer mode register

WDT : Watchdog timer

Figure 22-11. Non-Maskable Interrupt Request Acknowledge Timing

TMIF4 : Watchdog timer interrupt request flag

Instruction

The interrupt request generated in this period is acknowledged at timing.

Instruction CPU Instruction

TMIF4

PSW and PC Save, Jump

to Interrupt Servicing

Interrupt Sevicing

Program