Operation In Interval Timer Mode; Timing Of Overflow Flag (Ovf) Setting - Renesas H8S/2319 series Hardware Manual

11.3.2

Operation in Interval Timer Mode

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 11-5. This function can be used to
generate interrupt requests at regular intervals.
TCNT count
H'FF
H'00
WT/IT=0
TME=1
Legend
WOVI: Interval timer interrupt request generation
11.3.3

Timing of Overflow Flag (OVF) Setting

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 11-6.
φ
TCNT
Overflow signal
(internal signal)
OVF
Overflow Overflow
WOVI
Figure 11-5 Operation in Interval Timer Mode
H'FF
Figure 11-6 Timing of OVF Setting
Overflow
WOVI WOVI
Rev. 5.00, 12/03, page 417 of 1088
Overflow
Time
WOVI
H'00