KR100449445B1 - Method for stabilizing calibration of initialization routine for hdd through estimation error limit - Google Patents

Abstract

PURPOSE: A method for stabilizing calibration of an initialization routine for an HDD(Hard Disk Drive) by estimating error limit is provided to stabilize a calibration process by extending the estimation error limit when the HDD is initialized. CONSTITUTION: For power-on ready, a flag for notifying a register of the power-on ready is set(50). In case that the flag is set, the estimation error limit is extended to a value larger that the estimation error limit for a general track search mode. Track search is performed by loading the estimation error limit corresponding to a search section(52). When the track search is completed for all sections, the flag is reset(54).

Description

Calibration stabilization method by estimating error limits

The present invention relates to a calibration method performed in an initialization routine of a hard disk drive, and more particularly, to a method for stabilizing a calibration by estimating error limits.

In the conventional hard disk drive, the search performed by the initialization program at power on uses the value of the estimation error limit used in the general search after the drive ready, so the drive is in ready mode. The case often occurs and does not switch to. The reason for this is that the various power-on-ready scans have not yet stabilized because they have not yet undergone a calibration step. The calibration process performed at drive initialization is a process that automatically optimizes several servo gains for changes in the environment and the drive itself. Uncalibrated probes have several default calibration tables provided by default. However, the servo side has a weak characteristic. In particular, several searches from unlatch to outermost cylinders are more fragile due to a variety of causes.

In general, two criteria are used to determine a search error on the servo side. The first case is the case of continuously missing the detection of the servo address mark, which is the basis of the input signal. If this phenomenon continues, the host cannot be smoothly controlled. The computer will report a search error. That is, in the conventional hard disk drive, if the FSAM (Fail Servo Address Mark) occurs three or more times in succession, it is recognized that no further servo control is possible and shuts off the VCM and repeats the retry process.

In the second search error determination method, the difference between the control output value estimated in the servo controller itself and the actual drive output value (which is called an estimation error) increases due to various environmental changes and characteristics of various components in the drive itself. It is the case that control cannot be performed. The estimation error used as a reference is managed as a minimum value (defined as an estimation error limit) that can perform some control in the design. If the estimated error value continues to exceed the threshold, the servo controller shuts off the VCM as in the first case described above. In the conventional power-on-ready of a hard disk drive, the estimation error limit has been used with a normal estimation error limit at the time of searching performed after the power-on-ready. As a result, the estimation error increases due to the instability of the pre-calibration probes, which often causes the drive not to enter ready mode due to the overflow of the estimation error threshold.

Accordingly, an object of the present invention is to provide a method for stabilizing a calibration process by extending an estimation error limit upon initializing a hard disk drive.

In the present invention for achieving the above object, in the calibration stabilization method of a hard disk drive,

Setting a flag for notifying power on ready in a power on ready predetermined register;

If the flag is set, expanding the estimated error threshold to a value larger than the estimated error threshold in the normal track search mode;

Performing track search by loading estimated error thresholds corresponding to the search section;

And resetting the flag when the entire track search is completed.

1 is a block diagram of a typical hard disk drive.

2 is a control flow diagram of a microcontroller 22 of power " on " redish in accordance with one embodiment of the present invention.

3 is a flow chart of the discovery initialization subroutine in FIG.

Hereinafter, an operation according to an exemplary embodiment of the present invention will be described in detail with reference to the accompanying drawings. In the following description and drawings, numerous specific details are set forth in order to provide a more thorough understanding of the present invention, such as the extent of estimation error limits and the specific processing flow. It will be apparent to those skilled in the art that the present invention may be practiced without these specific details. And detailed descriptions of well-known functions and configurations that may unnecessarily obscure the subject matter of the present invention will be omitted.

1 shows a block diagram of a general hard disk drive, and shows an example of a hard disk drive having two disks 10 and four heads 12 corresponding thereto. Referring to FIG. 1, the disks 10 are typically stacked and mounted on the drive shaft of the spindle motor 34 and each disk surface corresponds to one head 12. The disk 10 typically consists of a plurality of tracks arranged concentrically and includes a parking zone in which the head 12 can be located when the drive is not in use (powered 'off' state). The head 12 is located on the surface of the disk 10 and is mounted to a vertically extending arm 14 of an annular voice coil motor (VCM) 28 arm assembly. The preamplifier 16 preamplifies and applies the read signal picked up by one of the heads 12 to the read / write channel circuit 18 when data is read. Encoded write data applied from the read / write channel circuit 18 is driven to drive the corresponding one of the heads 12 to be recorded on the disc 10. At this time, the preamplifier 16 selects one of the heads 12 under the control of a disk data controller (DDC) 36. The read / write channel circuit 18 decodes the read signal applied from the preamplifier 16 to generate read data RDATA. The read / write channel circuit 18 encodes the write data WDATA applied from the DDC 36 and applies it to the preamplifier 16. The read / write channel circuit 18 also demodulates the head position information which is a part of the servo information recorded on the disk 10 to generate a position error signal (PES). The PES generated from the read / write channel circuit 18 is applied to the A / D converter 20, and the A / D converter 20 converts the applied PES into a digital step value corresponding to its level so as to provide a microcontroller ( 22). The DDC 36 records data received from the host computer on the disk 10 through the read / write channel circuit 18 and the preamplifier 16 or transfers data reproduced from the disk 10 to the host computer. . The DDC 36 also interfaces the communication between the host computer and the microcontroller 22.

On the other hand, the microcontroller 22 controls the DDC 36 in response to a data read / write command received from the host computer and controls track search and track following. At this time, the micro controller 22 controls the track tracking by using the PES value input from the A / D converter 20 and responds to various servo control signals output from a gate array (not shown). Perform control. The D / A converter 24 converts a control value for position control of the heads 12 generated from the microcontroller 22 into an analog signal and outputs the analog signal. The VCM driver 26 generates a current I (t) for driving the actuator by a signal applied from the D / A converter 24 and applies it to the VCM 28. The VCM 28 located on the other side of the actuator having the heads 12 attached to one side moves the heads 12 horizontally on the disk 10 in response to the current direction and current level input from the VCM driver 26. Let's do it. The motor controller 30 controls the spindle motor driver 32 according to a control value for rotation control of the disks 10 generated from the microcontroller 22. The spindle motor driver 32 drives the spindle motor 34 to rotate the disks 10 under the control of the motor controller 30. The buffer memory 38 connected to the DDC 36 temporarily stores data transferred between the disk 10 and the host computer under the control of the DDC 36. The ROM 40 connected to the microcontroller 22 stores a control program and an estimated error threshold table according to a search section according to an embodiment of the present invention.

FIG. 2 shows a control flow diagram of the microcontroller 22 of power " on " redistribution according to one embodiment of the invention, and FIG. 3 shows a flow chart of the search initialization subroutine of FIG. Hereinafter, a calibration stabilization method through estimating an error limit according to an embodiment of the present invention will be described with reference to FIGS. 1 to 3.

In general, power on redundancy includes a mixture of sequences, which includes an unlatch of an initial actuator, an unlatch first search, a short distance search of a predetermined cylinder, and a calibration routine. In the following description, one embodiment of the present invention is described. It is assumed that the calibration stabilization routine according to is performed immediately before the power on ready.

First, the microcontroller 22 sets a flag for notifying a specific register that the power is on ready as part of an initialization process performed when the drive is powered on. Thereafter, when the microcontroller 22 issues a track search on the interface side of the DDC 36, the microcontroller 22 performs a search initialization subroutine as shown in FIG. 3 as an initialization process for starting the track search. When the search initialization subroutine is divided, the microcontroller 22 first checks in step 60 whether the flag for notifying that the power is ready to the specific register is set. If the specific flag is not set as a result of the test, the process proceeds to step 62. If the specific flag is set, the process proceeds to step 61. In step 61, the microcontroller 22 expands the estimation error threshold and proceeds to step 62, where the extended range is assumed to extend to twice the normal estimation error threshold used in the track search after the drive ready. On the other hand, in step 62, the microcontroller 22 sequentially loads the estimated error threshold for each search section and proceeds to step 64 to perform track search. In operation 66, the microcontroller 22 checks whether the full section search is completed. The search section means a long seek track, a medium seek track, a short seek track, and a short seek track, and the estimated error thresholds have different values according to the seek distance. Therefore, the microcontroller 22 sequentially performs steps 62 to 66 to perform track search by applying an estimated error limit determined for each search section. After the search is completed for the entire section, the microcontroller 22 returns to step 54 of FIG. 2 to reset the set specific flag and to switch to the ready mode. Therefore, during normal track search after the ready mode, the estimation error is searched by applying the normal estimation error threshold, and when the drive is initialized, the error of track search due to exceeding the estimation error threshold is checked by checking the estimation error by applying the extended estimation error threshold. The probability of occurrence can be lowered, and as a result, a stable calibration operation can be performed.

As described above, the present invention has an advantage that a stable calibration operation can be performed by performing track search by extending the estimation error limit during drive initialization.

Claims (2)

In the calibration stabilization method of a hard disk drive, The track search is performed by extending the estimated error limit for each power-on-red search section to a value larger than the estimated error limit in the normal track search mode. A calibration stabilization method comprising recovering tracks to estimated error limits. In the method of stabilizing the calibration of a hard disk drive, Setting a flag for notifying power on ready in a power on ready predetermined register; If the flag is set, expanding the estimated error threshold to a value larger than the estimated error threshold in the normal track search mode; Performing track search by loading estimated error thresholds corresponding to the search section; And resetting the flag when the entire track search is completed.