Datasheet
91
32059L–AVR32–01/2012
AT32UC3B
SR.CPCS bit, reconfigure the RA and RC registers for the lower channel with the real
values.
- OCD
1. The auxiliary trace does not work for CPU/HSB speed higher than 50MHz
The auxiliary trace does not work for CPU/HSB speed higher than 50MHz.
Fix/Workaround
Do not use the auxiliary trace for CPU/HSB speed higher than 50MHz.
- Processor and Architecture
1. LDM instruction with PC in the register list and without ++ increments Rp
For LDM with PC in the register list:
the instruction behaves as if the ++ field is always set, ie
the pointer is always updated. This happens even if the ++ field is cleared. Specifically, the
increment of the pointer is done in parallel with the testing of R12.
Fix/Workaround
None.
2. RETE instruction does not clear SREG[L] from interrupts
The RETE instruction clears SREG[L] as expected from exceptions.
Fix/Workaround
When using the STCOND instruction, clear SREG[L] in the stacked value of SR before
returning from interrupts with RETE.
3. RETS behaves incorrectly when MPU is enabled
RETS behaves incorrectly when MPU is enabled and MPU is configured so that system
stack is not readable in unprivileged mode.
Fix/Workaround
Make system stack readable in unprivileged mode, or return from supervisor mode using
rete instead of rets. This requires:
1. Changing the mode bits from 001 to 110 before issuing the instruction. Updating the
mode bits to the desired value must be done using a single mtsr instruction so it is done
atomically. Even if this step is generally described as not safe in the UC technical reference
manual, it is safe in this very specific case.
2. Execute the RETE instruction.
4. Privilege violation when using interrupts in application mode with protected system
stack
If the system stack is protected by the MPU and an interrupt occurs in application mode, an
MPU DTLB exception will occur.
Fix/Workaround
Make a DTLB Protection (Write) exception handler which permits the interrupt request to be
handled in privileged mode.
5. USART
6. ISO7816 info register US_NER cannot be read
The NER register always returns zero.
Fix/Workaround
None.