Datasheet
Rev.6.00 Oct.28.2004 page 461 of 1016
REJ09B0138-0600H
13.3.2 Interval Timer Operation
To use the WDT as an interval timer, clear the WT/IT bit in TCSR to 0 and set the TME bit to 1. An interval timer
interrupt (WOVI) is generated each time TCNT overflows, provided that the WDT is operating as an interval timer, as
shown in figure 13-5. This function can be used to generate interrupt requests at regular intervals.
TCNT count
H'00
Time
H'FF
WT/IT=0
TME=1
WOVI
Overflow Overflow Overflow Overflow
Legend:
WOVI: Interval timer interrupt re
q
uest
g
eneration
WOVI WOVI WOVI
Figure 13-5 Interval Timer Operation
13.3.3 Timing of Setting Overflow Flag (OVF)
The OVF flag is set to 1 if TCNT overflows during interval timer operation. At the same time, an interval timer interrupt
(WOVI) is requested. This timing is shown in figure 13-6.
ΓΈ
TCNT H'FF H'00
Overflow signal
(internal signal)
OVF
Figure 13-6 Timing of Setting of OVF