HD6432351 datasheet(569/1025 Pages) RENESAS

569 / 1025 page

Section 12 Watchdog Timer (WDT)

Rev. 3.00 Sep 15, 2006 page 535 of 988

REJ09B0330-0300

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

[Clearing condition]

Cleared by reading TCSR when OVF = 1, then writing 0 to OVF

(Initial value)

[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.

Bit 6

WT/

Description

Interval timer: Sends the CPU an interval timer interrupt request (WOVI)

when TCNT overflows

(Initial value)

Watchdog timer: Generates the

WDTOVF signal when TCNT overflows

Note:

* For details of the case where TCNT overflows in watchdog timer mode, see section

12.2.3, Reset Control/Status Register (RSTCSR).

Bit 5—Timer Enable (TME): Selects whether TCNT runs or is halted.

Bit 5

TME

Description

TCNT is initialized to H'00 and halted

(Initial value)

TCNT counts

Bits 4 and 3—Reserved: Read-only bits, always read as 1.

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