NEC 78K0 User Manual page 263

Table 11-2. Mask Option Setting and Watchdog Timer Operation Mode
Watchdog timer clock Fixed to f
source
Operation after reset Operation starts with the maximum interval
(f
R
Operation mode selection The interval can be changed only once.
Features The watchdog timer cannot be stopped.
Notes 1. As long as power is being supplied, Ring-OSC oscillation cannot be stopped (except in the reset
period).
2. The conditions under which clock supply to the watchdog timer is stopped differ depending on
the clock source of the watchdog timer.
<1> If the clock source is f
conditions.
• When f
• In HALT/STOP mode
• During oscillation stabilization time
<2> If the clock source is f
conditions.
• If the CPU clock is f
instruction
• In HALT/STOP mode
Remarks 1. f : Ring-OSC clock oscillation frequency
R
2. f : X1 input clock oscillation frequency
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CHAPTER 11 WATCHDOG TIMER
Ring-OSC Cannot Be Stopped
Note 1
.
R
18
/2 ).
, clock supply to the watchdog timer is stopped under the following
XP
is stopped
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, clock supply to the watchdog timer is stopped under the following
R
and if f
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*
User's Manual U15947EJ2V0UD
Mask Option
Ring-OSC Can Be Stopped by Software
• Selectable by software (f
• When reset is released: f
Operation starts with maximum interval
18
(f /2 ).
R
The clock selection/interval can be changed
only once.
The watchdog timer can be stopped in
Note 2
standby mode
is stopped by software before execution of the STOP
R
, f or stopped)
XP R
R
.
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