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Bit 7 Overflow Flag (OVF): A status flag that indicates that WTCNT has overflowed from
H'FF to H'00.
Bit 7
OVF
Description
0
[Clearing conditions]
1. Write 0 in the TME bit
2. Read WTCSR when OVF = 1, then write 0 in OVF
1
[Setting condition]
When WTCNT overflows (changes from H'FF to H'00)
When internal reset request generation is selected in watchdog timer mode, OVF is
cleared automatically by the internal reset
Bit 6 Timer Mode Select (WT/,7 ,7 ,7 ,7): Selects whether the WDT is used as a watchdog timer or
interval timer. If used as an interval timer, the WDT generates an interval timer interrupt request
(WOVI) when TCNT overflows. If used as a watchdog timer, the WDT generates a reset or NMI
interrupt when TCNT overflows.
Bit 6
WT/,7 ,7 ,7 ,7
Description
0
Interval timer mode: Sends the CPU an interval timer interrupt request (WOVI) when
WTCNT overflows
1
Watchdog timer mode: Sends the CPU a reset or NMI interrupt request when
WTCNT overflows
Bit 5 Timer Enable (TME): Selects whether WTCNT runs or is halted.
Bit 5
TME
Description
0
WTCNT is initialized to H'00 and halted
1
WTCNT counts
Bit 4 Reserved: This bit should not be set to 1.
Rev. 1.0, 02/00, page 351 of 1141
(Initial value)
(Initial value)
(Initial value)
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