CHAPTER 11 WATCHDOG TIMER FUNCTIONS
User’s Manual U16896EJ2V0UD
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11.2.4 Operation
Watchdog timer 2 automatically starts in the reset mode following reset release.
The WDTM2 register can be written to only once following reset through byte access. To use watchdog timer 2,
write the operation mode and the interval time to the WDTM2 register using 8-bit memory manipulation instructions.
After this is done, the operation of watchdog timer 2 cannot be stopped.
The watchdog timer 2 program loop detection time interval can be selected by the WDTM2.WDCS24 to
WDTM2.WDCS20 bits. Writing ACH to the WDTE register clears the counter of watchdog timer 2 and starts the count
operation again. After the count operation starts, write ACH to the WDTE register within the set program loop
detection time interval.
If the program loop detection time is exceeded without ACH being written to the WDTE register, a reset signal
(WDTRES2) or non-maskable interrupt request signal (INTWDT2) is generated depending on the set value of the
WDTM2.WDM21 and WDTM2.WDM20 bits.
To not use watchdog timer 2, write 1FH to the WDTM2 register.
For non-maskable interrupt servicing when the non-maskable interrupt request mode is set, refer to
17.10
Cautions
.
Because watchdog timer 2 operates in the HALT/IDLE/STOP mode, exercise care that the timer does not overflow
in the HALT/IDLE/STOP mode.
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