Panasonic MN101C77C - Manual (Page 318)

Chapter 9 Watchdog Timer
IX - 6 Operation
„ Watchdog Timer and CPU Mode
The relation between this watchdog timer and CPU mode features are as follows ;
(1) In NORMAL, IDLE, SLOW mode, the system clock is counted.
(2) The counting is continued regardless of switching at NORMAL, IDLE, SLOW mode.
(3) In HALT mode, the watchdog timer is stopped.
(4) In STOP mode, the watchdog timer is cleared automatically by hardware.
(5) In STOP mode, the watchdog interrupt cannot be generated.
(6) After releasing reset or recovering from STOP, the counting is executed for the duration of the
oscillation stabilization wait time.
Generally, in the system used STOP mode, if the STOP mode is done or not is divided on the program
execution, but, in this case, the counting value of the watchdog timer differs. So, the watchdog interrupt
should be prevented by setting the lowest value for watchdog timer clear.