Datasheet
109
[Not recommended for new designs - Use XMEGA A1U series] XMEGA A1 [DATASHEET]
8067O–AVR–06/2013
7. TWI, the minimum I
2
C SCL low time could be violated in Master Read mode
When the TWI is in Master Read mode and issuing 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
I
2
C specification could be violated.
Problem fix/Workaround
If this causes a potential problem in the application, software must ensure that the Repeated Start is never issued
before one SCL low time has passed.
8. Setting HIRES PR bit makes PWM output unavailable
Setting the HIRES Power Reduction (PR) bit for PORTx will make any Frequency or PWM output for the corre-
sponding Timer/Counters (TCx0 and TCx1) unavailable on the pin.
Problem fix/Workaround
Do not write the HIRES PR bit on PORTx when frequency or PWM output from TCx0/1 is used.
9. EEPROM erase and write does not work with all System Clock sources
When doing EEPROM erase or Write operations with other clock sources than the 2 MHz RCOSC, Flash will be
read wrongly for one or two clock cycles at the end of the EEPROM operation.
Problem fix/Workaround
Alt 1: Use the internal 2 MHz RCOSC when doing erase or write operations on EEPROM.
Alt 2: Ensure to be in sleep mode while completing erase or write on EEPROM. After starting erase or write opera-
tions on EEPROM, other interrupts should be disabled and the device put to sleep.
10. BOD will be enabled after any reset
If any reset source goes active, the BOD will be enabled and keep the device in reset if the VCC voltage is below
the programmed BOD level. During Power-On Reset, reset will not be released until VCC is above the pro-
grammed BOD level even if the BOD is disabled.
Problem fix/Workaround
Do not set the BOD level higher than VCC even if the BOD is not used.
11. Propagation delay analog Comparator increasing to 2 ms at -40 °C
When the analog comparator is used at temperatures reaching down to -40 °C, the propagation delay will increase
to ~2 ms.
Problem fix/Workaround
None