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Execution timing of self-calibration, By this compensation, loop gain becomes constant

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4.5 Self-calibration The forces are compensated by adding the measured value to the specified current value to the power amplifier. This makes the stable servo control. To compensate torque varying by the cylinder, the disk is divided into 23 areas from the innermost to the outermost circumference and the compensating value is measured at the measuring cylinder on each area at factory calibration. The measured values are stored in the SA cylinder. In the self-calibration, the compensating value is updated using the value in the SA cylinder. (2) Compensating open loop gain Torque constant value of the VCM has a dispersion for each drive, and varies depending on the cylinder that the head is positioned. To realize the high speed seek operation, the value that compensates torque constant value change and loop gain change of the whole servo system due to temperature change is measured and stored. For sensing, the firmware mixes the disturbance signal to the position signal at the state that the head is positioned to any cylinder. The firmware calculates the loop gain from the position signal and stores the compensation value against to the target gain as ratio. For compensating, the direction current value to the power amplifier is multiplied by the compensation value. By this compensation, loop gain becomes constant value and the stable servo control is realized. To compensate torque constant value change depending on cylinder, whole cylinders from most inner to most outer cylinder are divided into 16 partitions at calibration in the factory, and the compensation data is measured for representative cylinder of each partition. This measured value is stored in the SA area. The compensation value at self-calibration is calculated using the value in the SA area. 4.5.2 Execution timing of self-calibration Self-calibration is executed when: • The power is turned on. • The disk drive receives the RECALIBRATE command from the host. • The disk drive temperature changes by more than 10 degrees. C141-E120-02EN 4-9

Section	Page
Front Cover	1
FOR SAFE OPERATION	2
Revision History	3
Preface	5
Important Alert Items	9
Manual Organization	11
Contents	13
Figures	18
Tables	19
CHAPTER 1 Device Overview	21
1.1 Features	22
1.1.1 Functions and performance	22
1.1.2 Adaptability	22
1.1.3 Interface	23
1.2 Device Specifications	24
1.2.1 Specifications summary	24
1.2.2 Model and product number	25
1.3 Power Requirements	25
1.4 Environmental Specifications	27
1.5 Acoustic Noise	28
1.6 Shock and Vibration	28
1.7 Reliability	29
1.8 Error Rate	30
1.9 Media Defects	30
1.10Load/Unload Function	30
CHAPTER 2 Device Configuration	33
2.1 Device Configuration	34
2.2 System Configuration	36
2.2.1 ATA interface	36
2.2.2 1 drive connection	36
2.2.3 2 drives connection	36
CHAPTER 3 Installation Conditions	39
3.1 Dimensions	40
3.2 Mounting	41
3.3 Cable Connections	47
3.3.1 Device connector	47
3.3.2 Cable connector specifications	48
3.3.3 Device connection	48
3.3.4 Power supply connector (CN1)	49
3.4 Jumper Settings	49
3.4.1 Location of setting jumpers	49
3.4.2 Factory default setting	50
3.4.3 Master drive-slave drive setting	50
3.4.4 CSEL setting	51
CHAPTER 4 Theory of Device Operation	53
4.1 Outline	54
4.2 Subassemblies	54
4.2.1 Disk	54
4.2.2 Head	54
4.2.3 Spindle	55
4.2.4 Actuator	55
4.2.5 Air filter	55
4.3 Circuit Configuration	56
4.4 Power-on Sequence	59
4.5 Self-calibration	60
4.5.1 Self-calibration contents	60
4.5.2 Execution timing of self-calibration	61
4.5.3 Command processing during self-calibration	62
4.6 Read/write Circuit	62
4.6.1 Read/write preamplifier (HDIC)	62
4.6.2 Write circuit	62
4.6.3 Read circuit	65
4.6.4 Digital PLL circuit	66
4.7 Servo Control	67
4.7.1 Servo control circuit	67
4.7.2 Data-surface servo format	70
4.7.3 Servo frame format	72
4.7.4 Actuator motor control	73
4.7.5 Spindle motor control	74
CHAPTER 5 Interface	77
5.1 Physical Interface	78
5.1.1 Interface signals	78
5.1.2 Signal assignment on the connector	79
5.2 Logical Interface	82
5.2.1 I/O registers	83
5.2.2 Command block registers	84
5.2.3 Control block registers	89
5.3 Host Commands	89
5.3.1 Command code and parameters	90
5.3.2 Command descriptions	92
5.3.3 Error posting	164
5.4 Command Protocol	166
5.4.1 PIO Data transferring commands from device to host	166
5.4.2 PIO Data transferring commands from host to device	168
5.4.3 Commands without data transfer	170
5.4.4 Other commands	172
5.4.5 DMA data transfer commands	172
5.5 Ultra DMA Feature Set	175
5.5.1 Overview	175
5.5.2 Phases of operation	176
5.5.3 Ultra DMA data in commands	176
5.5.4 Ultra DMA data out commands	181
5.5.5 Ultra DMA CRC rules	185
5.5.6 Series termination required for Ultra DMA	186
5.6 Timing	187
5.6.1 PIO data transfer	187
5.6.2 Multiword data transfer	188
5.6.3 Ultra DMA data transfer	189
5.6.4 Power-on and reset	202
CHAPTER 6 Operations	203
6.1 Device Response to the Reset	204
6.1.1 Response to power-on	204
6.1.2 Response to hardware reset	205
6.1.3 Response to software reset	207
6.1.4 Response to diagnostic command	208
6.2 Power Save	209
6.2.1 Power save mode	209
6.2.2 Power commands	210
6.3 Defect Management	211
6.3.1 Spare area	211
6.3.2 Alternating defective sectors	211
6.4 Read-Ahead Cache	213
6.4.1 Data buffer configuration	214
6.4.2 Caching operation	214
6.4.3 Usage of read segment	216
6.5 Write Cache	222
Glossary	225
Acronyms and Abbreviations	229
Comment Form	231
Spine	233

Match case Limit results 1 per page

4.5

Self-calibration

C141-E120-02EN

4-9

The forces are compensated by adding the measured value to the specified current

value to the power amplifier.

This makes the stable servo control.

To compensate torque varying by the cylinder, the disk is divided into 23 areas

from the innermost to the outermost circumference and the compensating value is

measured at the measuring cylinder on each area at factory calibration.

The

measured values are stored in the SA cylinder.

In the self-calibration, the

compensating value is updated using the value in the SA cylinder.

(2)

Compensating open loop gain

Torque constant value of the VCM has a dispersion for each drive, and varies

depending on the cylinder that the head is positioned.

To realize the high speed

seek operation, the value that compensates torque constant value change and loop

gain change of the whole servo system due to temperature change is measured

and stored.

For sensing, the firmware mixes the disturbance signal to the position signal at the

state that the head is positioned to any cylinder.

The firmware calculates the loop

gain from the position signal and stores the compensation value against to the

target gain as ratio.

For compensating, the direction current value to the power amplifier is multiplied

by the compensation value.

By this compensation, loop gain becomes constant

value and the stable servo control is realized.

To compensate torque constant value change depending on cylinder, whole

cylinders from most inner to most outer cylinder are divided into 16 partitions at

calibration in the factory, and the compensation data is measured for

representative cylinder of each partition.

This measured value is stored in the SA

area.

The compensation value at self-calibration is calculated using the value in

the SA area.

4.5.2

Execution timing of self-calibration

Self-calibration is executed when:

•

The power is turned on.

•

The disk drive receives the RECALIBRATE command from the host.

•

The disk drive temperature changes by more than 10 degrees.