Datasheet

Section 14 Watchdog Timer (WDT)
Page 854 of 1408 R01UH0309EJ0500 Rev. 5.00
Sep 24, 2012
H8S/2456, H8S/2456R, H8S/2454 Group
14.4.2 Interval Timer Mode
To use the WDT as an interval timer, set the WT/IT bit to 0 and TME bit in TCSR to 1.
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.
When the TCNT overflows in interval timer mode, an interval timer interrupt (WOVI) is requested
at the same time the OVF bit in the TCSR is set to 1.
TCNT count
H'00
Time
H'FF
WT/IT=0
TME=1
WOVI
Overflow Overflow Overflow Overflow
Legend:
WOVI: Interval timer interrupt request generation
WOVI WOVI
WOVI
Figure 14.3 Operation in Interval Timer Mode
14.5 Interrupt Source
During interval timer mode operation, an overflow generates an interval timer interrupt (WOVI).
The interval timer interrupt is requested whenever the OVF flag is set to 1 in TCSR. OVF must be
cleared to 0 in the interrupt handling routine.
Table 14.2 WDT Interrupt Source
Name Interrupt Source Interrupt Flag DTC Activation
WOVI TCNT overflow OVF Impossible