ST6208C/ST6209C/ST6210C/ST6220C
WATCHDOG TIMER (Cont’d)
These instructions test the C bit and reset the
MCU (i.e. disable the Watchdog) if the bit is set
(i.e. if the Watchdog is active), thus disabling the
Watchdog.
Note: This note applies only when the watchdog is
used as a standard timer. It is recommended to
read the counter twice, as it may sometimes return
an invalid value if the read is performed while the
counter is decremented (counter bits in transient
state). To validate the return value, both values
read must be equal. The counter decrements eve-
For more information on the use of the watchdog,
please read application note AN1015.
ry 384 µs at 8 MHz fOSC
.
8.1.5 Low Power Modes
Mode Description
WAIT No effect on Watchdog.
Behaviour depends on the EXTCNTL option in the Option bytes:
1. Watchdog disabled:
STOP
The MCU will enter Stop mode if a STOP instruction is executed.
2. Watchdog enabled and EXTCNTL option disabled:
If a STOP instruction is encountered, it is interpreted as a WAIT.
3. Watchdog and EXTCNTL option enabled:
If a STOP instruction is encountered when the NMI pin is low, it is interpreted as a WAIT. If, however, the
STOP instruction is encountered when the NMI pin is high, the Watchdog counter is frozen and the CPU en-
ters STOP mode.
When the MCU exits STOP mode (i.e. when an interrupt is generated), the Watchdog resumes its activity.
8.1.6 Interrupts
None.
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