Fujitsu MHW2040AC User Manual Page 69
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4.7 Servo Control
(1) Microprocessor unit (MPU)
The MPU executes startup of the spindle motor, movement to the reference
cylinder, seek to the specified cylinder, and calibration operations.
The main internal operations of the MPU are shown below.
a. Spindle motor start
Starts the spindle motor and accelerates it to normal speed when power is
applied.
b. Move head to reference cylinder
Drives the VCM to position the head at the any cylinder in the data area. The
logical initial cylinder is at the outermost circumference (cylinder 0).
c. Seek to specified cylinder
Drives the VCM to position the head to the specified cylinder.
d. Calibration
Senses and stores the thermal offset between heads and the mechanical forces
on the actuator, and stores the calibration value.
(2) Servo burst capture circuit
The servo burst capture circuit reproduces signals (position signals) that indicate
the head position from the servo data on the data surface. From the servo area on
the data area surface, via the data head, the burst signals of EVEN1, ODD, EVEN2
are output as shown in Figure 4.8 in subsequent to the servo mark, gray code that
indicates the cylinder position, and index information. The servo signals do A/D-
convert by Fourier-demodulator in the servo burst capture circuit. At that time the
AGC circuit is in hold mode. The A/D converted data is recognized by the MPU as
position information.
(3) D/A converter (DAC)
The control program calculates the specified data value (digital value) of the VCM
drive current, and the value is converted from digital-to-analog so that an analog
output voltage is sent to the power amplifier.
(4) Power amplifier
The power amplifier feeds currents, corresponding to the DAC output signal
voltage to the VCM.
(5) Spindle motor control circuit
The spindle motor control circuit controls the sensor-less spindle motor. A spindle
driver IC with a built-in PLL circuit that is on a hardware unit controls the sensor-
less spindle motor.
C141-E258 4-13
- MHW2060AC, MHW2040AC 1
- DISK DRIVES 1
- PRODUCT MANUAL 1
- FOR SAFE OPERATION 2
- Revision History 3
- Preface 5
- Operating Environment 6
- Conventions 6
- Attention 7
- Liability Exception 7
- Important Alert Items 9
- Manual Organization 11
- Contents 13
- Illustrations 19
- CHAPTER 1 Device Overview 23
- 1.1 Features 24
- 1.1.3 Interface 25
- 1.2 Device Specifications 26
- 1.3 Power Requirements 29
- 1.5 Acoustic Noise 33
- 1.6 Shock and Vibration 33
- 1.7 Reliability 34
- 1.8 Error Rate 35
- 1.9 Media Defects 35
- 1.10 Load/Unload Function 35
- 2.1 Device Configuration 40
- 2.2 System Configuration 41
- 2.2.3 2 drives connection 42
- 3.1 Dimensions 44
- 3.2 Mounting 45
- Connector 50
- 3.3.3 Device connection 51
- 3.4 Jumper Settings 52
- 3.4.4 CSEL setting 54
- 4.1 Outline 58
- 4.2 Subassemblies 58
- 4.3 Circuit Configuration 59
- C141-E258 4-5 61
- 4.4 Power-on Sequence 62
- 4.5 Self-calibration 63
- 4.6 Read/write Circuit 65
- 4.6.3 Read circuit 66
- 4.6.4 Digital PLL circuit 67
- 4.7 Servo Control 68
- Theory of Device Operation 72
- 4-16 C141-E258 72
- 4.7.3 Servo frame format 73
- 4.7.5 Spindle motor control 75
- CHAPTER 5 Interface 77
- 5.1 Physical Interface 78
- 5.2 Logical Interface 82
- 5.2.1 I/O registers 83
- 5.3 Host Commands 90
- 5.3.2 Command descriptions 94
- • Default function 110
- • Unload Feature: 110
- • Attribute ID 123
- • Raw attribute value 124
- • Status Flag 124
- • Current attribute value 124
- • Error logging capability 127
- • Check sum 127
- • SMART error logging 128
- • Command data structure 130
- • Error data structure 130
- • Status 130
- • SMART self-test 131
- • Self-test number 131
- • Self-test index 131
- • Test span 132
- • Current LBA under test 132
- • Current span under test 132
- • Feature Flags 133
- (CM) 1 1 1 0 0 1 0 0 149
- • SET MAX ADDRESS 180
- Password information 182
- • SET MAX SET PASSWORD 184
- • SET MAX LOCK 184
- • SET MAX UNLOCK 184
- • Description 186
- 5.3.3 Error posting 203
- Interface 204
- 5-128 C141-E258 204
- 5.4 Command Protocol 205
- (*) Transfers dummy data 207
- 5.4.4 Other commands 211
- 5.5 Ultra DMA Feature Set 213
- 5.5.2 Phases of operation 214
- 5.5.5 Ultra DMA CRC rules 223
- 5.6 Timing 225
- 5.6.4 Power-on and reset 240
- CHAPTER 6 Operations 241
- 6.1.1 Response to power-on 242
- 6.2 Power Save 247
- 6.3 Defect Processing 249
- Sector (physical) 250
- Cylinder 0 250
- (Not used) 250
- 779 780 251
- 6.4 Read-ahead Cache 252
- For MPU work For R/W command 252
- 8,388,608 bytes 252
- 6.4.2 Caching operation 253
- 256
- 6.5 Write Cache 258
- Glossary 261
- Acronyms and Abbreviations 265
- Comment Form 273
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