Datasheet

254
AT32UC3A
NACK used in Slave Read mode:
0 = Each data byte has been correctly received by the Master.
1 = In read mode, a data byte has not been acknowledged by the Master. When NACK is set the programmer must not fill
THR even if TXRDY is set, because it means that the Master will stop the data transfer or re initiate it.
Note that in Slave Write mode all data are acknowledged by the TWI.
• ARBLST: Arbitration Lost (clear on read)
This bit is only used in Master mode.
0 = Arbitration won.
1 = Arbitration lost. Another master of the TWI bus has won the multi-master arbitration. TXCOMP is set at the same time.
• SCLWS: Clock Wait State (automatically set / reset)
This bit is only used in Slave mode.
0 = The clock is not stretched.
1 = The clock is stretched. THR / RHR buffer is not filled / emptied before the emission / reception of a new character.
SCLWS behavior can be seen in Figure 24-26 on page 242 and Figure 24-27 on page 243.
• EOSACC: End Of Slave Access (clear on read)
This bit is only used in Slave mode.
0 = A slave access is being performing.
1 = The Slave Access is finished. End Of Slave Access is automatically set as soon as SVACC is reset.
EOSACC behavior can be seen in Figure 24-28 on page 244 and Figure 24-29 on page 244
• ENDRX: End of RX buffer
This bit is only used in Master mode.
0 = The Receive Counter Register has not reached 0 since the last write in RCR or RNCR.
1 = The Receive Counter Register has reached 0 since the last write in RCR or RNCR.
• ENDTX: End of TX buffer
This bit is only used in Master mode.
0 = The Transmit Counter Register has not reached 0 since the last write in TCR or TNCR.
1 = The Transmit Counter Register has reached 0 since the last write in TCR or TNCR.
• RXBUFF: RX Buffer Full
This bit is only used in Master mode.
0 = RCR or RNCR have a value other than 0.
1 = Both RCR and RNCR have a value of 0.
• TXBUFE: TX Buffer Empty
This bit is only used in Master mode.
0 = TCR or TNCR have a value other than 0.
32058K
AVR32-01/12