Section 15 Watchdog Timer (WDT)
Rev. 3.00 Jan 25, 2006 page 380 of 872
REJ09B0286-0300
If the RST/
NMI
bit of TCSR is set to 1, when the TCNT overflows, an internal reset signal for this
LSI is issued for 518 system clocks, and the low level signal is simultaneously output from the
RESO
pin for 132 states, as shown in figure 15.2. If the RST/
NMI
bit is cleared to 0, when the
TCNT overflows, an NMI interrupt request is generated. Here, the output from the
RESO
pin
remains high.
An internal reset request from the watchdog timer and a reset input from the
RES
pin are
processed in the same vector. Reset source can be identified by the XRST bit status in SYSCR.
If a reset caused by a signal input to the
RES
pin occurs at the same time as a reset caused by a
WDT overflow, the
RES
pin reset has priority and the XRST bit in SYSCR is set to 1.
An NMI interrupt request from the watchdog timer and an interrupt request from the NMI pin are
processed in the same vector. Do not handle an NMI interrupt request from the watchdog timer
and an interrupt request from the NMI pin at the same time.
TCNT value
H'00
Time
H'FF
WT/
IT
= 1
TME = 1
Write H'00 to
TCNT
WT/
IT
= 1
TME = 1
Write H'00 to
TCNT
518 System clocks
Internal reset signal
Legend:
WT/
IT
:
TME:
OVF:
Overflow
OVF = 1
*
Timer mode select bit
Timer enable bit
Overflow flag
Note:
*
After the OVF bit becomes 1, it is cleared to 0 by an internal reset.
The XRST bit is also cleared to 0.
Figure 15.2 Watchdog Timer Mode (RST/
NMI
NMI
NMI
NMI
= 1) Operation
Содержание H8S/2158
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Страница 126: ...Section 4 Exception Handling Rev 3 00 Jan 25 2006 page 72 of 872 REJ09B0286 0300...
Страница 198: ...Section 6 Bus Controller Rev 3 00 Jan 25 2006 page 144 of 872 REJ09B0286 0300...
Страница 326: ...Section 10 8 Bit PWM Timer PWM Rev 3 00 Jan 25 2006 page 272 of 872 REJ09B0286 0300...
Страница 440: ...Section 15 Watchdog Timer WDT Rev 3 00 Jan 25 2006 page 386 of 872 REJ09B0286 0300...
Страница 606: ...Section 17 I 2 C Bus Interface IIC Rev 3 00 Jan 25 2006 page 552 of 872 REJ09B0286 0300...
Страница 742: ...Section 19 Multimedia Card Interface MCIF Rev 3 00 Jan 25 2006 page 688 of 872 REJ09B0286 0300...
Страница 744: ...Section 20 Encryption Operation Circuit DES and GF Rev 3 00 Jan 25 2006 page 690 of 872 REJ09B0286 0300...
Страница 750: ...Section 21 D A Converter Rev 3 00 Jan 25 2006 page 696 of 872 REJ09B0286 0300...
Страница 768: ...Section 22 A D Converter Rev 3 00 Jan 25 2006 page 714 of 872 REJ09B0286 0300...
Страница 770: ...Section 23 RAM Rev 3 00 Jan 25 2006 page 716 of 872 REJ09B0286 0300...
Страница 824: ...Section 26 Clock Pulse Generator Rev 3 00 Jan 25 2006 page 770 of 872 REJ09B0286 0300...
Страница 844: ...Section 27 Power Down Modes Rev 3 00 Jan 25 2006 page 790 of 872 REJ09B0286 0300...
Страница 878: ...Section 28 List of Registers Rev 3 00 Jan 25 2006 page 824 of 872 REJ09B0286 0300...
Страница 926: ...Index Rev 3 00 Jan 25 2006 page 872 of 872 REJ09B0286 0300...