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

32072H–AVR32–10/2012

Data is to be received in 
slave receiver mode, 
SR.STREN is cleared, and 
RHR is full

TWCK is not stretched, read data is discarded.

SR.ORUN is set.

Data is to be transmitted in 
slave receiver mode, 
SR.STREN is cleared, and 
THR is empty

TWCK is not stretched, previous contents of THR is written to bus.

SR.URUN is set.

SMBus timeout received

SR.SMBTOUT is set.

TWCK and TWD are immediately released.

Slave transmitter in SMBus 
PEC mode has transmitted 
a PEC byte, that was not 
identical to the PEC 
calculated by the master 
receiver.

Master receiver will transmit a NAK as usual after the last byte of a 
master receiver transfer.

Master receiver will retry the transfer at a later time.

Slave receiver discovers 
SMBus PEC Error

SR.SMBPECERR is set.

NAK returned after the data byte.

Bus Events