
399
Bit 7—Overflow Flag (OVF):
Indicates that TCNT has overflowed from H'FF to H'00, when in
interval timer mode. This flag cannot be set during watchdog timer operation.
Bit 7
OVF
Description
0
[Clearing condition]
Cleared by reading TCSR when OVF = 1, then writing 0 to OVF
(Initial value)
1
[Setting condition]
Set when TCNT overflows (changes from H'FF to H'00) in interval timer mode
Bit 6—Timer Mode Select (WT/
IT
):
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 the
WDTOVF
signal* when TCNT overflows.
Note: * The
WDTOVF
pin function is not supported by the F-ZTAT version.
Bit 6
WT/
IT
Description
0
Interval timer: Sends the CPU an interval timer interrupt request (WOVI)
when TCNT overflows
Watchdog timer: Generates the
WDTOVF
signal
*
1
when TCNT overflows
*
2
Notes: 1. The
WDTOVF
pin function is not supported by the F-ZTAT version.
2. For details of the case where TCNT overflows in watchdog timer mode, see section
11.2.3, Reset Control/Status Register (RSTCSR).
(Initial value)
1
Bit 5—Timer Enable (TME):
Selects whether TCNT runs or is halted.
Bit 5
TME
Description
0
TCNT is initialized to H'00 and halted
(Initial value)
1
TCNT counts
Bits 4 and 3—Reserved:
Read-only bits, always read as 1.