Datasheet

Table Of Contents
Section 12 Watchdog Timer (WDT)
REJ09B0140-0900 Rev. 9.00 Page 375 of 846
Sep 16, 2010
H8S/2215 Group
12.3.3 Interval Timer Mode
To use the WDT as an interval timer, clear bit WT/IT in TCSR to 0 and set bit TME to 1. When
the interval timer is operating, an interval timer interrupt (WOVI) is generated each time the
TCNT overflows. Therefore, an interrupt can be generated at intervals.
TCNT count
H'00
Time
H'FF
WT/IT = 0
TME = 1
WOVI
Overflow Overflow Overflow Overflow
Legend:
WOVI: Interval interrupt request generation
WOVI WOVI WOVI
Figure 12.4 Operation in Interval Timer Mode
12.3.4 Timing of Setting of 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 12.5.
φ
TCNT H'FF H'00
Overflow signal
(internal signal)
OVF
Figure 12.5 Timing of OVF Setting