Section 13 Watchdog Timer (WDT)
Rev. 2.00 Mar 09, 2006 page 546 of 906
REJ09B0292-0200
13.2.2
Watchdog Timer Control/Status Register (WTCSR)
Bit:
7
6
5
4
3
2
1
0
OVF
WT/
IT
TME
—
—
CKS2
CKS1
CKS0
Initial value:
0
0
0
1
1
0
0
0
R/W:
R/(W)
*
R/W
R/W
R
R
R/W
R/W
R/W
Note:
*
Only 0 can be written in bit 7, to clear the flag.
The watchdog timer control/status register (WTCSR) is an 8-bit read/write register. The method of
writing to WTCSR differs from that of most other registers to prevent inadvertent rewriting. See
section 13.2.4, Notes on Register Access, for details. Its functions include selecting the timer
mode and clock source. Bits 7 to 5 are initialized to 000 by a reset, in standby mode, when the
clock frequency is changed, and in clock pause mode. Bits 2 to 0 are initialized to 000 by a reset,
but are not initialized in standby mode, when the clock frequency is changed, or in clock pause
mode.
Bit 7—Overflow Flag (OVF): Indicates that WTCNT has overflowed from H'FF to H'00 in
interval timer mode. It is not set in watchdog timer mode.
Bit 7: OVF
Description
0
No overflow of WTCNT in interval timer mode
(Initial value)
Cleared by reading OVF, then writing 0 in OVF
1
WTCNT overflow in interval timer mode
Bit 6—Timer Mode Select (WT/
IT
): Selects whether to use the WDT as a watchdog timer or
interval timer. When WTCNT overflows, the WDT either generates an interval timer interrupt
(ITI) or generates a
WDTOVF
signal, depending on the mode selected.
Bit 6: WT/
IT
IT
IT
IT
Description
0
Interval timer mode: interval timer interrupt (ITI) request to the CPU
when WTCNT overflows
(Initial value)
1
Watchdog timer mode:
WDTOVF
signal output externally when WTCNT
overflows. Section 13.2.3, Reset Control/Status Register (RSTCSR),
describes in detail what happens when WTCNT overflows in watchdog
timer mode
Содержание SH7616
Страница 10: ...Rev 2 00 Mar 09 2006 page x of xxvi ...
Страница 132: ...Section 2 CPU Rev 2 00 Mar 09 2006 page 106 of 906 REJ09B0292 0200 ...
Страница 568: ...Section 12 16 Bit Free Running Timer FRT Rev 2 00 Mar 09 2006 page 542 of 906 REJ09B0292 0200 ...
Страница 582: ...Section 13 Watchdog Timer WDT Rev 2 00 Mar 09 2006 page 556 of 906 REJ09B0292 0200 ...
Страница 662: ...Section 14 Serial Communication Interface with FIFO SCIF Rev 2 00 Mar 09 2006 page 636 of 906 REJ09B0292 0200 ...
Страница 706: ...Section 16 Serial I O SIO Rev 2 00 Mar 09 2006 page 680 of 906 REJ09B0292 0200 ...
Страница 820: ...Section 19 Pin Function Controller PFC Rev 2 00 Mar 09 2006 page 794 of 906 REJ09B0292 0200 ...
Страница 932: ...Appendix D Package Dimensions Rev 2 00 Mar 09 2006 page 906 of 906 REJ09B0292 0200 ...
Страница 935: ...SH7616 Hardware Manual ...