upd78f0124hgba1-8et-a Renesas Electronics Corporation., upd78f0124hgba1-8et-a Datasheet - Page 221

• Manufacturer Part Number: upd78f0124hgba1-8et-a
• Description: 8-bit Single-chip Microcontrollers
• Manufacturer: Renesas Electronics Corporation.

(4) When CPU clock and watchdog timer operation clock are the internal oscillation clocks (f
10.4.4 Watchdog timer operation in HALT mode (when “internal oscillator can be stopped by software” is
high-speed system clock (f
the watchdog timer is the high-speed system clock (f
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.
The watchdog timer stops counting during HALT instruction execution regardless of whether the CPU clock is the
Figure 10-7. Operation in STOP Mode (CPU Clock and WDT Operation Clock: Internal Oscillator Clock)
CPU operation
STOP instruction is executed
When the STOP instruction is executed, operation of the watchdog timer is stopped. After STOP mode is
released, 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.
CPU operation
Watchdog timer
Watchdog timer
selected by option byte)
f
f
f
XP
XP
XT
f
f
R
R
Normal operation
Normal operation
(internal
oscillation clock)
Operating
Operating Operation stopped
XP
), internal oscillation clock (f
Operation stopped
Oscillation
stopped
Figure 10-8. Operation in HALT Mode
STOP
HALT
CHAPTER 10 WATCHDOG TIMER
User’s Manual U16962EJ3V0UD
Clock supply stopped
XP
Oscillation stabilization time
) or internal oscillation clock (f
(set by OSTS register)
17 clocks
R
), or subsystem clock (f
Operating
Normal operation (internal oscillation clock)
Normal operation
Operating
XT
), or whether the operation clock of
R
). After HALT mode is released,
R
) when the
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