CHAPTER 9 WATCHDOG TIMER
Preliminary User’s Manual U16898EJ1V0UD
150
(2) When the watchdog timer operation clock is the low-speed Ring-OSC clock (f
RL
) when the STOP
instruction is executed
When the STOP instruction is executed, operation of the watchdog timer is stopped. After STOP mode is
released, operation stops for 8 clocks of the low-speed Ring-OSC clock and then counting is started again using
the operation clock before the operation was stopped. At this time, the counter is not cleared to 0 but holds its
value.
Figure 9-7. Operation in STOP Mode (WDT Operation Clock: Low-Speed Ring-OSC Clock)
<1> CPU clock: Crystal/ceramic oscillation clock
Operating
Oscillation stabilization time
Normal operation
Oscillation stabilization time
(set by OSTS register)
Watchdog timer
Operation stopped
Operating
f
RL
f
CPU
CPU operation
Normal
operation
STOP
Oscillation stopped
Operation
stopped
(8/f
RL
)
<2> CPU clock: High-speed Ring-OSC clock or external clock input
Operating
Normal operation
Watchdog timer
Operation stopped
Operating
f
RL
f
CPU
CPU operation
Normal
operation
STOP
Oscillation stopped
Operation
stopped
(8/f
RL
)
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