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Bit 6—Timer Mode Select (WT/IT): Selects whether to use the WDT as a watchdog timer or
interval timer. If used as an interval timer, the WDT generates an interval timer interrupt request
when TCNT overflows. If used as a watchdog timer, the WDT generates a reset signal when
TCNT overflows.
Bit 6
WT/IT
Description
0
Interval timer: requests interval timer interrupts
1
Watchdog timer: generates a reset signal
Bit 5—Timer Enable (TME): Selects whether TCNT runs or is halted. When WT/IT = 1, clear
the software standby bit (SSBY) to 0 in SYSCR before setting TME. When setting SSBY to 1,
TME should be cleared to 0.
Bit 5
TME
Description
0
TCNT is initialized to H'00 and halted
1
TCNT is counting
Bits 4 and 3—Reserved: These bits cannot be modified and are always read as 1.
Bits 2 to 0—Clock Select 2 to 0 (CKS2 to CKS0): These bits select one of eight internal clock
sources, obtained by prescaling the system clock (φ), for input to TCNT.
Bit 2
Bit 1
Bit 0
CKS2
CKS1
CKS0
0
0
0
1
1
0
1
1
0
0
1
1
0
1
Description
φ/2
φ /32
φ /64
φ /128
φ /256
φ /512
φ /2048
φ /4096
(Initial value)
(Initial value)
(Initial value)
353
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