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3. shall delay at least one transmit setup time;
4. shall transition the ACK signal;
5. shall hold the DB(15-0) signals valid for at least one transmit hold time;
6. shall not change the ACK signal for a minimum of one transmit assertion period; and
7. may then change or release the DB(15-0) signals.
If the I/O signal is false (i.e., transfer to the target), to receive SPI information units, the target:
1. shall read the value of the DB(15-0) signals within one receive hold time of the transition of the ACK;
2. shall not transition the REQ signal for the current SPI information unit until the initiator has responded
with all ACK transitions for the previous SPI information unit.
As a result of a SPI information unit always being an even number of transfers, the REQ and ACK signals are
negated both before and after the transmission of the SPI information unit.
3.5.2.2.1.1
DT DATA IN phase information unit transfer exception condition handling
The initiator shall not negate the ACK for the last byte of the last iuCRC in an information unit until the entire
information unit has been verified and any required attention condition has been established.
If the nexus has been fully identified (i.e., an I_T_L_Q nexus has been established) and the initiator detects an
iuCRC error in any information unit (other than a SPI status information unit) it receives while in the DT DATA
IN phase, the initiator shall create an attention condition on or before the last iuCRC within the failed informa-
tion unit is acknowledged. When the target switches to a MESSAGE OUT phase, the initiator should send a
SCSI initiator port Detected Error message (see Section 4.3.5) to the target. This message notifies the target
that data in the information unit was invalid.
If a SCSI initiator port detects an iuCRC error in a SPI status information unit, the initiator shall create an atten-
tion condition on or before the last iuCRC of the information unit is acknowledged. If the target detects an
attention condition, it shall switch to a MESSAGE OUT phase and the initiator shall send a SCSI initiator port
Detected Error message (see Section 4.3.5) or an ABORT TASK message to the target. These messages
notify the target that the SPI status information unit was invalid and the message received from the initiator was
a SCSI initiator port Detected Error message.
If the information unit that failed was not a SPI status information unit, then the target shall send a SPI L_Q/SPI
status information unit pair to the initiator with a CHECK CONDITION status and a sense key set to Aborted
Command and an additional sense code set to Initiator Detected Error Message Received for the task associ-
ated with the received INITIATOR DETECTED ERROR message.
If the information unit that failed was a SPI status information unit and the message received was a SCSI initi-
ator port Detected Error message, then the target shall retry transferring the SPI L_Q/SPI status information
unit pair to the initiator with the original status information.
If the information unit that failed was a SPI status information unit and the message received was an ABORT
TASK message, then the target shall cause a bus free by generating a BUS FREE phase.
If the initiator is receiving a SPI L_Q information unit and the initiator detects an iuCRC error (i.e., the nexus
identification fails) while in the DT DATA IN phase, the initiator shall create an attention condition on or before
the iuCRC is acknowledged. When the target switches to a MESSAGE OUT phase, the initiator should send a
SCSI initiator port Detected Error message (see Section 4.3.5) to the target. This message notifies the target
that the nexus identification failed. The target shall then cause a bus free by generating a BUS FREE phase,
however, the target shall retry the task associated with the failed SPI L_Q information unit.
If the initiator receives a SPI L_Q information unit with a type code that is not defined in Table 50, that initiator
shall create an attention condition after negating the ACK for the last byte of the iuCRC in the SPI L_Q informa-
tion unit and before negating the ACK for the last byte of the last iuCRC in the information unit that follows the
SPI L_Q information unit. When the target switches to a MESSAGE OUT phase, the initiator shall send an
Parallel SCSI Interface Product Manual, Rev. A
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