123
CHAPTER 8 WATCHDOG TIMER
User’s Manual U15104EJ2V0UD
(2) Watchdog timer mode register (WDTM)
This register sets the watchdog timer operating mode and enables/disables counting.
WDTM is set with a 1-bit or 8-bit memory manipulation instruction.
Reset input clears WDTM to 00H.
Figure 8-3. Format of Watchdog Timer Mode Register (WDTM)
Notes 1. Once set to 1, RUN cannot be cleared to 0 by software. Therefore, use RESET input to clear RUN
to 0.
2. Once set to 1, WDTM3 and WDTM4 cannot be cleared to 0 by software.
3. WDTM starts interval timer operation at a time RUN is set to 1.
Caution
When RUN is set to 1 so that the watchdog timer is cleared, the actual overflow time is up
to 0.5% shorter than the time set by the timer clock select register (WDCS).
Remark
×
: Don’t care
RUN
<7>
0
6
0
WDTM4
4
WDTM3
3
2
1
0
FFF9H
Address
WDTM
Symbol
0
0
0
5
00H
After reset
R/W
R/W
RUN
0
1
Watchdog timer operating mode selection
Note 1
WDTM3
Watchdog timer operating mode selection
Note 2
WDTM4
Interval timer mode
Note 3
(Maskable interrupt occurs upon generation of an overflow.)
Watchdog timer mode 1
(Non-maskable interrupt occurs upon generation of an overflow.)
Watchdog timer mode 2
(Reset operation is activated upon generation of an overflow.)
×
0
1
0
1
1
Count stop
Counter is cleared and counting starts.
Содержание mPD178053
Страница 2: ...2 User s Manual U15104EJ2V0UD MEMO ...