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32142DS–06/2013
ATUC64/128/256L3/4U
Under certain circumstances, the lock signal from the Phase Locked Loop (PLL) oscillator
may not go back to zero after the PLL oscillator has been disabled. This can cause the prop-
agation of clock signals with the wrong frequency to parts of the system that use the PLL
clock.
Fix/Workaround
PLL must be turned off before entering STOP, DEEPSTOP or STATIC sleep modes. If PLL
has been turned off, a delay of 30us must be observed after the PLL has been enabled
again before the SCIF.PLL0LOCK bit can be used as a valid indication that the PLL is
locked.
3. PLLCOUNT value larger than zero can cause PLLEN glitch
Initializing the PLLCOUNT with a value greater than zero creates a glitch on the PLLEN sig-
nal during asynchronous wake up.
Fix/Workaround
The lock-masking mechanism for the PLL should not be used.
The PLLCOUNT field of the PLL Control Register should always be written to zero.
4. RCSYS is not calibrated
The RCSYS is not calibrated and will run faster than 115.2kHz. Frequencies around 150kHz
can be expected.
Fix/Workaround
If a known clock source is available the RCSYS can be runtime calibrated by using the fre-
quency meter (FREQM) and tuning the RCSYS by writing to the RCCR register in SCIF.
5. Writing 0x5A5A5A5A to the SCIF memory range will enable the SCIF UNLOCK feature
The SCIF UNLOCK feature will be enabled if the value 0x5A5A5A5A is written to any loca-
tion in the SCIF memory range.
Fix/Workaround
None.
6.3.4 WDT
1. Clearing the Watchdog Timer (WDT) counter in second half of timeout period will
issue a Watchdog reset
If the WDT counter is cleared in the second half of the timeout period, the WDT will immedi-
ately issue a Watchdog reset.
Fix/Workaround
Use twice as long timeout period as needed and clear the WDT counter within the first half
of the timeout period. If the WDT counter is cleared after the first half of the timeout period,
you will get a Watchdog reset immediately. If the WDT counter is not cleared at all, the time
before the reset will be twice as long as needed.
2. WDT Control Register does not have synchronization feedback
When writing to the Timeout Prescale Select (PSEL), Time Ban Prescale Select (TBAN),
Enable (EN), or WDT Mode (MODE) fieldss of the WDT Control Register (CTRL), a synchro-
nizer is started to propagate the values to the WDT clcok domain. This synchronization
takes a finite amount of time, but only the status of the synchronization of the EN bit is
reflected back to the user. Writing to the synchronized fields during synchronization can lead
to undefined behavior.
Fix/Workaround
-When writing to the affected fields, the user must ensure a wait corresponding to 2 clock
cycles of both the WDT peripheral bus clock and the selected WDT clock source.
-When doing writes that changes the EN bit, the EN bit can be read back until it reflects the
written value.
