Datasheet

253
XMEGA B [DATASHEET]
8291B–AVR–01/2013
Table 19-7. TWI slave acknowledge actions.
 Bit 1:0 – CMD[1:0]: Command
Writing these bits trigger the slave operation as defined by Table 19-8. The CMD bits are strobe bits and always read as
zero. The operation is dependent on the slave interrupt flags, DIF and APIF. The acknowledge action is only executed
when the slave receives data bytes or address byte from the master.
Table 19-8. TWI slave command.
Writing the CMD bits will automatically clear the slave interrupt flags and CLKHOLD, and release the SCL line. The
ACKACT bit and CMD bits can be written at the same time, and then the acknowledge action will be updated before the
command is triggered.
ACKACT Action
0 Send ACK
1 Send NACK
CMD[1:0] Group Configuration DIR Operation
00 NOACT X No action
01 X Reserved
10 COMPLETE
Used to complete transaction
0
Execute acknowledge action succeeded by waiting for
any START (S/Sr) condition
1 Wait for any START (S/Sr) condition
11 RESPONSE
Used in response to an address byte (APIF is set)
0
Execute acknowledge action succeeded by reception
of next byte
1
Execute acknowledge action succeeded by DIF being
set
Used in response to a data byte (DIF is set)
0
Execute acknowledge action succeeded by waiting for
the next byte
1 No operation