Programmable microcontroller architecture for disk drive system

Details Programmable microcontroller architecture for disk drive system Programmable microcontroller architecture for disk drive system

1993-05-14

2001-08-21

Pan, Daniel H. (Department: 2183)

Electrical computers and digital processing systems: processing

Processing control

Branching

C712S227000, C711S219000, C711S171000, C369S032010, C710S266000

Reexamination Certificate

active

06279108

ABSTRACT:

FIELD OF THE INVENTION
The present invention is generally related to rotating media type data storage devices and, in particular, to a software system for controlling secondary mass data storage devices typically employing rotating magnetic media for the storage and retrieval of data in support of high-performance data processing systems.
BACKGROUND OF THE INVENTION
There has been and continues to be an ever-creasing demand for secondary mass storage peripherals capable of storing ever greater amounts of data in machine-readable form. This desire is coupled to a need to concurrently decrease the average time required to access any particular stored data. In addition, there is the commercial necessity to also reduce the costs associated with such secondary mass data storage devices.
Advances in the development of conventional hard-disk drive type data storage peripherals have been made to generally satisfy, albeit temporarily, the aforementioned desires. The principal gains in total data storage capability come from improvements in the achievement of linear recording bit densities in excess of 14,000 flux changes per inch and track densities of greater than 1,000 per inch. Some gains in the reduction of average access times have come from mechanical improvements in the actuator arm design and construction. Some measurable gains have also been achieved through the utilization of dedicated electronic controllers to manage actuator seek operation and thereby yield a net reduction in the average access time. This use of dedicated hardware is often extended to provide dedicated control of the spin motor rate of rotation and the closed loop actuator control needed to precisely follow a single track. This extended use of dedicated electronic control hardware is generally encouraged since it broadly reduces the cost of manufacture and assembly of disk drives.
Unfortunately, the use of dedicated electronic hardware architecturally reduces the design, initial setup and long term operative flexibility of the disk drive. Unique trimming or tailoring of the electronic and mechanical components of a disk drive, particularly with respect to one another, is sacrificed for the low cost mass producibility of the dedicated electronic control hardware.
The use of non-dedicated electronic hardware in place of dedicated hardware also raises problems. The coordination of multiple active processors in real-time is difficult and the multiplicity of hardware, both of the processors and the coordinating control logic, increases complexity and cost. Alternately, the utilization of a single active processor in place of the dedicated hardware is conventionally avoided due the apparently necessary intricacy of the diverse control functions that must be performed each in real time. Further, each function must be performed in the very limited real-time available every time the function is required to avoid corrupting the subsequent operation of the system.
SUMMARY OF THE INVENTION
A purpose of the present invention is therefore to realize a highly flexible disk drive control system utilizing a single active processor that, by the architectural design of its embedded software, operated reliably in real time and retains a high degree of flexibility while remaining imminently mass producible at low cost.
This is achieved in the present invention by the provision of a control architecture for supporting a rotating media in the storage and retrieval of data, where the rotating media stores data in tracks of multiple sectors. The control architecture is implemented utilizing a microcontroller capable of executing control tasks and a control program that schedules plural control tasks temporally distributed for respective execution during the rotational period of a predetermined sector. The scheduling of the plural control tasks is synchronized with respect to data retrieved from the predetermined sector.
The plural control tasks include a rotation control task for determining an adjustment to the spin speed of the rotating media, a track following task for determining an adjustment to the alignment of the a read/write head with respect to the predetermined track and a sector timing task for determining the position of a read/write head with respect to the predetermined track. The sector timing task also provides for scheduling the rotation control and track following tasks for execution during discrete intervals during the rotational period of the predetermined sector as well as scheduling the re-execution of the sector timing task with respect to the rotational period of another predetermined sector.
Thus, an advantage of the present invention is that all of the required support process can be realized in real time while utilizing only a single microcontroller.
Another advantage of the present invention is that maximum usage of the microcontroller's execution capability is obtained through the temporally based scheduling of the control tasks. Very little execution time is devoted to determine the next task for performance and whether any required information or data is not yet available, as is typical of conventional real time process control.
A further advantage of the present invention is that the temporally based scheduling of tasks is synchronized to the occurrence of data on the rotating media under normal operating conditions, thereby allowing the task scheduling vary with each sector period to preserve, under a wide range of environmental change, the operating margins needed to complete each task and realize a successful operation with respect to the processing of each data sector.
Still another advantage of the present invention is that it allows for an optimal portion of the rotating media control processed to be implemented in the software control program of the microcontroller to minimize the complexity and extent of the microcontroller's complement of support hardware.


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