![](http://datasheet.mmic.net.cn/100000/IF180C52TXXX-20R_datasheet_3493957/IF180C52TXXX-20R_815.png)
815
32099I–01/2012
AT32UC3L016/32/64
- When entering Shutdown mode while debugging the chip using JTAG or aWire interface
In the listed cases, writing a one to the bit VREGCR.POR33MASK in the System Control
Interface (SCIF) to mask the POR33 reset will be ineffective
Fix/Workaround
- Do not disable POR33 using the user interface
- Do not use the SM33 supply monitor
- Do not enter Shutdown mode if a debugger is connected to the chip
4.
Instability when exiting sleep walking
If all the following operating conditions are true, exiting sleep walking might lead to
instability:
- The OSC0 is enabled in external clock mode (OSCCTRL0.OSCEN == 1 and
OSCCTRL0.MODE == 0)
- A sleep mode where the OSC0 is automatically disabled is entered
- The device enters sleep walking
Fix/Workaround
Do not run OSC0 in external clock mode if sleepwalking is expected to be used.
5.
Clock Failure Detector (CFD) can be issued while turning off the CFD
While turning off the CFD, the CFD bit in the Status Register (SR) can be set. This will
change the main clock source to RCSYS.
Fix/Workaround
Solution 1: Enable CFD interrupt. If CFD interrupt is issues after turning off the CFD, switch
back to original main clock source.
Solution 2: Only turn off the CFD while running the main clock on RCSYS.
6.
Sleepwalking in idle and frozen sleep mode will mask all other PB clocks
If the CPU is in idle or frozen sleep mode and a module is in a state that triggers sleep walk-
ing, all PB clocks will be masked except the PB clock to the sleepwalking module.
Fix/Workaround
Mask all clock requests in the PM.PPCR register before going into idle or frozen mode.
35.2.4
SCIF
1.
PCLKSR.OSC32RDY bit might not be cleared after disabling OSC32K
In some cases the OSC32RDY bit in the PCLKSR register will not be cleared when OSC32K
is disabled.
Fix/Workaround
When re-enabling the OSC32K, read the PCLKSR.OSC32RDY bit. If this bit is:
0: Follow normal procedures.
1: Ignore the PCLKSR.OSC32RDY and ISR.OSC32RDY bit. Use the Frequency Meter
(FREQM) to determine if the OSC32K clock is ready. The OSC32K clock is ready when the
FREQM measures a non-zero frequency.
2.
The RC32K output on PA20 is not always permanently disabled
The RC32K output on PA20 may sometimes re-appear.
Fix/Workaround
Before using RC32K for other purposes, the following procedure has to be followed in order
to properly disable it:
- Run the CPU on RCSYS
- Disable the output to PA20 by writing a zero to PM.PPCR.RC32OUT
- Enable RC32K by writing a one to SCIF.RC32KCR.EN, and wait for this bit to be read as
one