Datasheet
104
[Not recommended for new designs - Use XMEGA A1U series] XMEGA A1 [DATASHEET]
8067O–AVR–06/2013
32. Accessing EBI address space with PREBI set will lock Bus Master
If EBI Power Reduction Bit is set while EBI is enabled, accessing external memory could result in bus hang-up,
blocking all further access to all data memory.
Problem fix/Workaround
Ensure that EBI is disabled before setting EBI Power Reduction bit.
33. RTC Counter value not correctly read after sleep
If the RTC is set to wake up the device on RTC Overflow and bit 0 of RTC CNT is identical to bit 0 of RTC PER as
the device is entering sleep, the value in the RTC count register can not be read correctly within the first prescaled
RTC clock cycle after wakeup. The value read will be the same as the value in the register when entering sleep.
The same applies if RTC Compare Match is used as wake-up source.
Problem fix/Workaround
Wait at least one prescaled RTC clock cycle before reading the RTC CNT value.
34. Pending asynchronous RTC-interrupts will not wake up device
Asynchronous Interrupts from the Real-Time-Counter that is pending when the sleep instruction is executed, will
be ignored until the device is woken from another source or the source triggers again.
Problem fix/Workaround
None.
35. TWI, the minimum I
2
C SCL low time could be violated in Master Read mode
If the TWI is in Master Read mode and issues a Repeated Start on the bus, this will immediately release the SCL
line even if one complete SCL low period has not passed. This means that the minimum SCL low time in the I2C
specification could be violated.
Problem fix/Workaround
If this is a problem in the application, ensure in software that the Repeated Start is never issued before one SCL
low time has passed.
36. TWI address-mask feature is non-functional
The address-mask feature is non-functional, so the TWI can not perform hardware address match on more than
one address.
Problem fix/Workaround
If the TWI must respond to multiple addresses, enable Promiscuous Mode for the TWI to respond to all address
and implement the address-mask function in software.