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7.7 Bus Conditions
C156-E228-02EN 7-41
(2) Response against ATTENTION condition (TARG)
The TARG must enter the MESSAGE OUT phase and respond to the
ATTENTION condition under the following situations. After terminating the
MESSAGE OUT phase and sending back a MESSAGE REJECT message, the
TARG must reenter the MESSAGE OUT phase if the ATN signal is true.
• When the ATN signal becomes true in the COMMAND phase, the TARG
must initiate the MESSAGE OUT phase immediately after the command
(command descriptor block [CDB]) has completed the transfer of all or some
bytes.
• When the ATN signal becomes true in the DATA phase, the TARG must
enter the MESSAGE OUT phase immediately after the DATA phase. The
TARG can enter the MESSAGE OUT phase at any time. (For example, the
data transfer need not be terminated at a logical data block boundary.) The
INIT must continue REQ/ACK handshaking (DATA phase) until the bus
phase changes.
• When the ATN signal becomes true in the STATUS phase, the TARG must
enter the MESSAGE OUT phase after the status byte transfer is completed.
• When the ATN signal becomes true in the MESSAGE IN phase, the TARG
must enter the MESSAGE OUT phase immediately after transferring the
current message.
• When the ATN signal becomes true in the SELECTION phase, the selected
TARG must enter the MESSAGE OUT phase immediately after the
SELECTION phase.
• When the ATN signal becomes true in the RESELECTION phase, the TARG
must enter the MESSAGE OUT phase after the IDENTIFY message
transmission is completed.