Interval Timer Mode - Renesas H8S Family Hardware Manual

Section 12 Watchdog Timer (WDT)
12.4.2

Interval Timer Mode

When the WDT is used as an interval timer, an interval timer interrupt (WOVI) is generated each
time the TCNT overflows, as shown in figure 12.3. Therefore, an interrupt can be generated at
intervals. When the TCNT overflows in interval timer mode, an interval timer interrupt (WOVI) is
requested at the same time the OVF bit of TCSR is set to 1. The timing is shown in figure 12.4.
TCNT value
H'FF
H'00
WT/IT = 0
TME = 1
WOVI : Interval timer interrupt request occurrence
φ
TCNT
Overflow signal
(internal signal)
OVF
Rev. 1.00 Mar. 12, 2008 Page 422 of 1178
REJ09B0403-0100
Overflow Overflow
WOVI WOVI
Figure 12.3 Interval Timer Mode Operation
H'FF
Figure 12.4 OVF Flag Set Timing
Overflow Overflow
WOVI WOVI
H'00
Time