Scsi control zero (scntl0), Register: 0x00 – Avago Technologies LSI53C1010R User Manual
Page 142
4-24
Registers
Version 2.2
Copyright © 2000–2003 by LSI Logic Corporation. All rights reserved.
Register: 0x00
SCSI Control Zero (SCNTL0)
Read/Write
ARB[1:0]
Arbitration Mode Bits 1 and 0
[7:6]
A combination of the ARB bits selects either Simple or
Full arbitration.
Simple Arbitration
1.
The LSI53C1010R SCSI function waits for a bus free
condition to occur.
2.
It asserts SBSY/ and its SCSI ID, contained in the
register, onto the SCSI bus. If
the SSEL/ signal is asserted by another SCSI
device, the LSI53C1010R SCSI function deasserts
SBSY/, deasserts its ID, and sets the Lost Arbitration
bit (bit 3) in the
register.
3.
After an arbitration delay, the CPU should read the
register to check if
a higher priority SCSI ID is present. If no higher
priority ID bit is set, and the Lost Arbitration bit is not
set, the LSI53C1010R SCSI function wins arbitration.
4.
When the LSI53C1010R SCSI function wins
arbitration, SSEL/ must be asserted using the
SCSI Output Control Latch (SOCL)
for a bus clear
and a bus settle delay (1.2
µ
s). Then, a low level
selection is performed.
7
6
5
4
3
2
1
0
ARB[1:0]
START
WATN
EPC
CRCOK
AAP
TRG
1
1
0
0
0
x
0
0
ARB1
ARB0
Arbitration Mode
0
0
Simple arbitration
0
1
Reserved
1
0
Reserved
1
1
Full arbitration, selection/reselection