Synchronized Reference Signal Characteristics - Seagate Barracuda ST12550W Product Manual

18
Rotational position locking
Note. Mode Select page 4, byte 17, bits 1 and 0.
RPL Description
00b Spindle synchronization is disabled (default value)
01b The target operates as a synchronized-spindle slave
10b The target operates as a synchronized-spindle master
11b The target operates as a synchronized-spindle master control
(not supported by the disc drive)
The VIC 2 LSI on the master drive provides the reference signal (SSREF ).
The index signal generates a 120 Hz signal. The signal is normally
false/negated (nominal 0V) and makes a transition to the true/asserted
(nominal +5V) level to indicate the reference position during the revolution
period. Master and slave drives use the trailing (falling) edge of the
reference signal to phase-lock their spindles. A maximum of 10 seconds
is allowed for a slave to synchronize with the reference signal. Figure 5
shows the characteristics of the reference signal.
Spindle synchronization input requirements:
SSREF +:Period (T) 0.0083 seconds ( 1.0% max)
Cycle-to-cycle variance:
Phase error while synchronized:
1
SSREF +
0
Figure 5. Synchronized reference signal characteristics
SCSI interface factors
The Rotational Position Locking (RPL) field in byte 17 (bits 0 and 1) of the
Rigid Disc Drive Geometry mode parameters page (page 04h) is used for
enabling and disabling spindle synchronization mode (see the SCSI-2
Interface Product Manual ). If the target fails to synchronize, it creates a unit
attention condition to all initiators. The sense key is set to Unit Attention and
the additional sense code is set to Spindle Synchronized (5C01).
After reaching synchronization, if the target detects a change of synchroni-
zation and:
1. If the logical unit is not executing an I/O process for the initiator, then the
target creates a unit attention condition. The sense key is set to Unit
Attention and the additional sense code is set to Spindle Synchronized
(5C01) or Spindle Not Synchronized (5C02).
2. If the logical unit is executing an I/O process and no other error occurs,
then the target returns Check Condition status. The sense key is set to
Recovered Error if the target is able to complete the I/O process or to
Hardware Error if the target is unable to complete the I/O process. The
additional sense code is set to Spindle Synchronized (5C01) or Spindle
Not Synchronized (5C02).
Barracuda 1 and 2 Product Manual, Rev. C
10 microseconds
20 microseconds
T
1.0 sec min.
1.37 sec max.