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11.2 Watchdog Timer 2
11.2.1 Functions
Watchdog timer 2 has the following functions.
• Default start watchdog timer
→ Reset mode: Reset operation upon overflow of watchdog timer 2 (generation of WDTRES2 signal)
→ Non-maskable interrupt request mode: NMI operation upon overflow of watchdog timer 2 (generation of
Note 2
INTWDT2 signal)
• Input selectable from internal oscillation clock and subclock as the source clock
Notes 1. Watchdog timer 2 automatically starts in the reset mode following reset release.
When watchdog timer 2 is not used, either stop its operation before reset is executed through this
function, or clear once watchdog timer 2 and stop it within the next interval time.
Also, write to the WDTM2 register for verification purposes only once, even if the default settings
(reset mode, interval time: f
2. For non-maskable interrupt servicing due to a non-maskable interrupt request signal (INTWDT2),
refer to 17.10 Cautions.
Clock
f
/8
R
input
f
controller
XT
2
Watchdog timer enable
register (WDTE)
Remark f
:
Internal oscillation clock frequency
R
f
:
Subclock frequency
XT
INTWDT2:
Non-maskable interrupt request signal through watchdog timer 2
WDTRES2: Watchdog timer 2 reset signal
CHAPTER 11 WATCHDOG TIMER FUNCTIONS
Note 1
25
/2
) need not be changed.
XX
Figure 11-2. Block Diagram of Watchdog Timer 2
12
19
f
/2
to f
/2
R
R
16-bit
Selector
counter
or
9
16
f
/2
to f
/2
XT
XT
Clear
0
WDM21 WDM20
WDCS24
Watchdog timer mode
register 2 (WDTM2)
Internal bus
User's Manual U16896EJ2V0UD
Output
controller
3
3
WDCS23
WDCS22
WDCS21 WDCS20
INTWDT2
WDTRES2
(internal reset signal)
353
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