CHAPTER 10 WATCHDOG TIMER FUNCTION
320
User’s Manual U15109EJ3V0UD
(3) Watchdog timer mode register (WDTM)
This register sets the operating mode of the watchdog timer, enables and disables counting, and generates
internal reset signals.
WDTM is set by an 8-bit or 1-bit memory manipulation instruction.
RESET input sets WDTM to 00H.
After reset: 00H
R/W
Address: FFFFF384H
<7>
6
5
4
3
2
1
0
WDTM
RUN
0
0
WDTM4
WDTM3
0
0
0
RUN
Operating mode selection for the watchdog timer
Note 1
0
Disable count
1
Clear count and start counting
WDTM4
Operating mode selection for the watchdog timer
Note 2
0
Interval timer mode
(If an overflow occurs, the maskable interrupt INTWDTM is generated.)
1
Watchdog timer mode 1
(If an overflow occurs, the non-maskable interrupt INTWDT is generated.)
WDTM3
Internal reset signal generation selection
Note 2
0
Internal reset signal not generated when overflow
1
Internal reset signal generated when overflow
Notes 1.
Once RUN is set (1), the register cannot be cleared (0) by software. Therefore, when the count
starts, the count cannot be stopped except by RESET input.
2.
Once WDTM3 and WDTM4 are set (1), the registers cannot be cleared (0) by software.
Caution
If RUN is set (1) and the watchdog timer is cleared, the actual overflow time may be up to 2
12
/f
XX
seconds shorter than the set time.