Method of operating hard disk drives, corresponding hard disk drive and processing device
AssigneeSTMicroelectronics S.r.l.
InventorsMarco Ferrari, Davide Betta, Diego Tognoli, Roberto Trabattoni
Life of this patent
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Abstract
In accordance with an embodiment, a hard disk drive includes voice coil motors (VCMs) coupled to respective control units configured to drive retract an operation of the VCMs in the hard disk drive. The retract operation of the VCMs includes a sequence of retract steps. The control units are allotted respective time slots for communication over a communication line with the respective time slots synchronized via the common clock line, and are configured to drive sequences of retract steps of the VCMs in the hard disk drive in a timed relationship.
Claims20
A control circuit for a hard disk drive system, comprising:
- a register map configured to store a slave enable signal and a clock buffer enable signal;
- a clock interface circuit comprising a first buffer stage and a second buffer stage, the clock interface circuit configured to selectively apply a clock signal to a common clock line or receive the clock signal from the common clock line based on a master-slave configuration enable signal, the master-slave configuration enable signal being a function of the slave enable signal and the clock buffer enable signal stored in the register map;
- and
- a finite state machine configured to manage communication control and monitoring functions over a communication line based on the master-slave configuration enable signal, wherein the master-slave configuration enable signal determines whether the control circuit operates in a master status or a slave status.
A method of controlling retract operations in a hard disk drive system having a master voice coil motor control circuit and a slave voice coil motor control circuit coupled via a communication line, the method comprising:
- generating a retract start pulse on the communication line to communicate that a retract phase has started;
- executing, by each of the master voice coil motor control circuit and the slave voice coil motor control circuit, a sequence of retract stages comprising a brake stage, a first park stage, and a second park stage;
- generating, by each of the master voice coil motor control circuit and the slave voice coil motor control circuit, a respective pulse on the communication line after completing each retract stage;
- and
- controlling timing of the retract stages based on timer values associated with each of the master voice coil motor control circuit and the slave voice coil motor control circuit, wherein the timer values determine whether retract stages are executed immediately or after waiting for a specific time determined by counting pulses on the communication line.
A method of operating a hard disk drive system during startup, the method comprising:
- identifying, by a system on chip, slave voice coil motor control circuits in the hard disk drive system;
- setting the identified slave voice coil motor control circuits to a waiting state in response to addressing the slave voice coil motor control circuits;
- identifying a master voice coil motor control circuit after setting the slave voice coil motor control circuits to the waiting state;
- generating, by the master voice coil motor control circuit, a clock signal on a common clock line in response to being identified;
- generating, by the master voice coil motor control circuit, a pattern on a communication line that marks a zero time slot for all slave voice coil motor control circuits;
- and
- capturing and recording, by each of the slave voice coil motor control circuits, the zero time slot from the communication line while in the waiting state.
Dependencies are inferred from the claim text.