UPD78F9234MC-5A4-A Datasheet, PDF (164/419 Pages) Renesas Technology Corp – Old Company Name in Catalogs and Other Documents

CHAPTER 9 WATCHDOG TIMER
9.4.4 Watchdog timer operation in HALT mode (when “low-speed internal oscillator can be stopped by
software” is selected by option byte)
The watchdog timer stops counting during HALT instruction execution regardless of whether the operation clock of
the watchdog timer is the system clock (fX) or low-speed internal oscillation clock (fRL). After HALT 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 Normal operation
fCPU
Figure 9-8. Operation in HALT Mode
HALT
Normal operation
fX or fRL
Watchdog timer
Operating Operation stopped
Operating
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User’s Manual U17446EJ5V0UD