Atmel Xplained Evaluation Board AT32UC3A3-XPLD AT32UC3A3-XPLD Data Sheet
Product codes
AT32UC3A3-XPLD
1005
32072H–AVR32–10/2012
AT32UC3A3
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.
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.
In the PRAS and PRBS registers, the MxPR fields are only two bits
In the PRAS and PRBS registers, the MxPR fields are only two bits wide, instead of four bits.
The unused bits are undefined when reading the registers.
Fix/Workaround
Mask undefined bits when reading PRAS and PRBS.
In the PRAS and PRBS registers, the MxPR fields are only two bits wide, instead of four bits.
The unused bits are undefined when reading the registers.
Fix/Workaround
Mask undefined bits when reading PRAS and PRBS.
Multiply instructions do not work on RevD
All the multiply instructions do not work.
Fix/Workaround
Do not use the multiply instructions.
All the multiply instructions do not work.
Fix/Workaround
Do not use the multiply instructions.
MPU
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.
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.
39.3.2
USB
UPCFGn.INTFRQ is irrelevant for isochronous pipe
As a consequence, isochronous IN and OUT tokens are sent every 1 ms (Full Speed), or
every 125uS (High Speed).
Fix/Workaround
For higher polling time, the software must freeze the pipe for the desired period in order to
prevent any "extra" token.
As a consequence, isochronous IN and OUT tokens are sent every 1 ms (Full Speed), or
every 125uS (High Speed).
Fix/Workaround
For higher polling time, the software must freeze the pipe for the desired period in order to
prevent any "extra" token.
39.3.3
ADC
Sleep Mode activation needs additional A to D conversion
If the ADC sleep mode is activated when the ADC is idle the ADC will not enter sleep mode
before after the next AD conversion.
Fix/Workaround
Activate the sleep mode in the mode register and then perform an AD conversion.
If the ADC sleep mode is activated when the ADC is idle the ADC will not enter sleep mode
before after the next AD conversion.
Fix/Workaround
Activate the sleep mode in the mode register and then perform an AD conversion.
39.3.4
USART
ISO7816 info register US_NER cannot be read
The NER register always returns zero.
The NER register always returns zero.