Interval Timer Mode; Timing Of Setting Of Overflow Flag (Ovf); Figure 12.4 Operation In Interval Timer Mode; Figure 12.5 Timing Of Ovf Setting - Hitachi H8S/2215 Series Hardware Manual

12.3.3

Interval Timer Mode

When the WDT is used as an interval timer, an interval timer interrupt (WOVI) is generated each
time the TCNT overflows. Therefore, an interrupt can be generated at intervals.
TCNT count
H'FF
H'00
WT/ = 0
TME = 1
WOVI: Interval interrupt request generation
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.
ø
TCNT
Overflow signal
(internal signal)
OVF
Overflow
WOVI

Figure 12.4 Operation in Interval Timer Mode

H'FF

Figure 12.5 Timing of OVF Setting

Overflow Overflow
WOVI WOVI
Rev. 3.0, 10/02, page 353 of 686
Overflow
Time
WOVI
H'00 ø1
ø1
ø1