Serial Attached SCSI (SAS) Interface
Table 1.5 OOB signal transmitter requirements
Signal
COMINIT/RESET
COMSAS
To transmit an OOB signal, a transmitter shall repeat these steps six times:
1) transmit D.C. idle for an idle time; and
2) transmit an ALIGN burst for a burst time.
It shall then transmit D.C. idle for an OOB signal negation time.
The ALIGNs used in OOB signals should be at generation 1 (G1) physical link rates
(i.e., 1,5 Gbps). The ALIGNs are only required to generate an envelope for the
detection circuitry, as required for any signaling that may be A.C. coupled. If G2
ALIGNs are used, the number of ALIGNs doubles compared with G1 ALIGNs.
A SAS transmitter should transmit ALIGNs at the G1 physical link rate to create
the burst portion of the OOB signal, but may transmit ALIGNs at its lowest
supported physical link rate if it is not able to transmit at the G1 physical link rate
and shall not transmit them at a physical link rate faster than its lowest supported
physical link rate.
Figure 1.8 describes OOB signal transmission by the SP transmitter.
ALIGN burst
1
COMINIT
idle
ALIGN burst
1
1
COMSAS idle
1-14
Burst time
160 OOBI
160 OOBI
COMRESET/COMINIT
1
2
3
4
2
3
4
5
COMSAS
2
3
4
2
3
4
Figure 1.8 OOB signal transmission
Idle time
Negation time
480 OOBI
1440 OOBI
COMINIT
Transmitt
5
6
6
COMINIT
negation
COMSAS
5
6
Transmitted
5
6
COMSAS
negation
800 OOBI
2400 OOBI
C141-C009