360050398

 

 

 

 

10.8.27 Power Control

 

(Exh)

 

 

 

 

 

 

 

 

COMMAND CODE

 

1 1 1 0 X X X X

REGISTER

 

 

REGISTER SETTING

NORMAL COMPLETION

 

DR

 

drive no.

no change

 

CY

 

 

 

no change

 

HD

 

 

 

no change

 

SN

 

 

 

no change

 

SC

shown below

00/FFH (for E5/98 command)

 

 

 

 

 

no change (for other command)

 

FT

 

 

 

no change

Power Control is a group of commands which controls low power mode in the drive. The drive has three types of power mode:

Idle, Stand-by and Sleep mode

At the completion of disk access, the drive automatically enters the idle mode.

There are two ways to shift to the stand-by mode ( to stop rotation of spindle motor ).

By a command from the host

By internal timer

The internal timer is set by Stand-by or Idle command. If the drive receives disk access command from the host when it is in stand-by mode , the spindle starts rotating and the drive executes read/write operation.

After power on, the spindle starts rotating and enters the idle mode. During idle or stand-by, READY bit is set and the drive is ready to receive a command.

To be specific , there are four different sub-commands defined by lower 4 bits of command as follows. The drive is in the idle mode when it is in default condition after power- on.

10.8.27.1 Stand-by Immediate (E0/94)

SC=X (Don't care)

The drive enters the stand-by mode immediately by this command. If the drive is already in the stand-by mode, it does no-operation and the stand-by timer doesn’t start .The drive issues an interrupt and reports the host that the command has been completed before it virtually enters the stand-by mode .

10.8.27.2 Idle Immediate (E1/95)

SC=X

The drive enters the idle mode immediately by this command. If the drive is already in the idle mode, it does no-operation. If stand-by timer is enabled, timer will start. After the drive enters the idle mode, the drive issues interrupt to report the host that the command has been completed.

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