Atmel Xplained Evaluation Board AT32UC3A3-XPLD AT32UC3A3-XPLD Data Sheet

Product codes
AT32UC3A3-XPLD
Page of 1021
1008
32072H–AVR32–10/2012
AT32UC3A3
Fix/Workaround
Disable and then enable the peripheral after the transfer error. 
AES
URAD (Unspecified Register Access Detection Status) does not detect read accesses
to the write-only KEYW[5..8]R registers
Fix/Workaround
None. 
39.3.5
HMATRIX
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. 
39.3.6
TWIM
TWIM SR.IDLE goes high immediately when NAK is received
When a NAK is received and there is a non-zero number of bytes to be transmitted,
SR.IDLE goes high immediately and does not wait for the STOP condition to be sent. This
does not cause any problem just by itself, but can cause a problem if software waits for
SR.IDLE to go high and then immediately disables the TWIM by writing a one to CR.MDIS.
Disabling the TWIM causes the TWCK and TWD pins to go high immediately, so the STOP
condition will not be transmitted correctly.
Fix/Workaround
If possible, do not disable the TWIM. If it is absolutely necessary to disable the TWIM, there
must be a software delay of at least two TWCK periods between the detection of
SR.IDLE==1 and the disabling of the TWIM. 
TWIM TWALM polarity is wrong
The TWALM signal in the TWIM is active high instead of active low.
Fix/Workaround
Use an external inverter to invert the signal going into the TWIM. When using both TWIM
and TWIS on the same pins, the TWALM cannot be used. 
TWIS
TWIS Version Register reads zero
TWIS Version Register (VR) reads zero instead of 0x112.
Fix/Workaround
None. 
39.3.7
MCI
The busy signal of the responses R1b is not taken in account for CMD12
STOP_TRANSFER
It is not possible to know the busy status of the card during the response (R1b) for the com-
mands CMD12.
Fix/Workaround
The card busy line should be polled through the GPIO Input Value register (IVR) for com-
mands CMD12.