Avago Technologies LSI53C1010R User Manual
Page 143
SCSI Registers
4-25
Version 2.2
Copyright © 2000–2003 by LSI Logic Corporation. All rights reserved.
Full Arbitration, Selection/Reselection
1.
The LSI53C1010R SCSI function waits for a bus free
condition.
2.
It asserts SBSY/ and its SCSI ID onto the SCSI bus.
The SCSI ID asserted is the highest priority ID
stored in the
register.
3.
If the SSEL/ signal is asserted by another SCSI
device or if the LSI53C1010R SCSI function detects
a higher priority ID, the LSI53C1010R SCSI function
deasserts SBSY/, deasserts its ID, sets the Lost
Arbitration bit, bit 3 in the
register, and waits until the next bus free state to try
arbitration again.
4.
The LSI53C1010R SCSI function repeats arbitration
until it wins control of the SCSI bus. When it wins,
the Won Arbitration bit is set in the
register, bit 2.
5.
The LSI53C1010R SCSI function performs selection
by asserting SSEL/, the target’s ID (stored in the
register), and the
LSI53C1010R ID (stored in the
register) onto the SCSI bus.
6.
After a selection is complete, the Function Complete
bit is set in the
SCSI Interrupt Status Zero (SIST0)
register, bit 6.
7.
If a selection time-out occurs, the Selection Time-out
bit is set in the
SCSI Interrupt Status One (SIST1)
register, bit 2.
START
Start Sequence
5
When this bit is set, the LSI53C1010R starts the
arbitration sequence indicated by the Arbitration Mode
bits. The Start Sequence bit is accessed directly in low
level mode; during SCSI SCRIPTS operations, this bit is
controlled by the SCRIPTS processor. Do not start an
arbitration sequence if the connected (CON) bit in the
register, bit 4, is set. This
bit indicates that the LSI53C1010R is already connected
to the SCSI bus. This bit is automatically cleared when