Oscillator calibration for motor controller

• US 8,046,185 B1
• Filed: 08/11/2010
• Issued: 10/25/2011
• Est. Priority Date: 05/30/2007
• Status: Active Grant

• Current Assignee: Marvell Asia Pte Limited (Marvell Technology Group Limited)
• Original Assignee: Marvell International Limited (Marvell Technology Group Limited)
• Inventors: Chui, Siew Yong
• Primary Examiner(s): Nghiem; Michael
• Assistant Examiner(s): Le; Toan M
• Application Number:
  US12/854,737
• Time in Patent Office: 440 Days
• Field of Search: 702/89, 702/57, 702 79- 81, 702 84- 85, 702/90, 702106-107, 702/127, 702/176, 702/178, 702182-183, 369/8, 369/19, 369/47.36, 369/60.01, 369128-129, 360/51, 360/73.03, 360/77.08, 331/2, 331/13, 331/18, 331/23, 331/25, 331/34, 331/44, 331 46- 48, 331/55, 331/158, 327141-144, 700108-109, 73/10.1, 73/14.2
• US Class Current: 702/89
• CPC Class Codes: G11B 5/54 with provision for moving the head into or out of its operative position or across tracks
• CPC Class Codes: G11B 5/59616 Synchronisation; Clocking G11B5/59622 takes precedence

Abstract

Systems, methods, and apparatuses including computer program products for oscillator calibration include, in at least one implementation, a storage device including: a system including a first clock source, a second clock source, and a motor controller, the motor controller including calibration circuitry configured to calibrate the second clock source according to the first clock source in response to the first clock source operating as expected, and configured to provide to the system the calibrated second clock source as a timing reference instead of the first clock source as the timing reference in response to the first clock source not operating as expected, a head actuator configured to communicate with the motor controller, and a spindle disposed within the system.

Claims

1. A storage device comprising:

a system that includes;

a first clock source;

a second clock source; and

a motor controller, the motor controller including calibration circuitry configured to calibrate the second clock source according to the first clock source in response to the first clock source operating as expected, and configured to provide to the system the calibrated second clock source as a timing reference instead of the first clock source as the timing reference in response to the first clock source not operating as expected;

a head actuator configured to communicate with the motor controller; and

a spindle disposed within the system.

2. The storage device of claim 1, wherein the first clock source is a system clock.

3. The storage device of claim 2, wherein the second clock source is an internal oscillator.

4. The storage device of claim 3, wherein the calibration circuitry includes monitor circuitry configured to evaluate operation of the system to determine if the system clock is operating as expected.

5. The storage device of claim 1, wherein the calibration circuitry includes monitor circuitry configured to evaluate states of a state machine of the storage device.

6. The storage device of claim 5, wherein one state of the state machine is a stop state, wherein emergency parking is performed in the stop state and the calibration circuitry is configured to use the second clock source for a timing reference instead of the first clock source in the stop state.

7. The storage device of claim 1, wherein the motor controller is configured to use the second clock source as the timing reference to determine a sequence to perform emergency parking.

8. The storage device of claim 1, wherein the calibration circuitry is configured to determine a calibration value using the first clock source and the second clock source when the system is operating in accordance to an operating condition.

9. The storage device of claim 8, wherein the operating condition includes the system being powered and the first clock source being operational.

10. The storage device of claim 8, further including a register that stores the calibration value.

11. The storage device of claim 1, wherein the calibration circuitry is configured to couple to an emergency power supply that is configured to supply power to the second clock source and the calibration circuitry.

12. The storage device of claim 11, wherein the emergency power supply is an electromagnetic force created by the spindle.

13. The storage device of claim 1, wherein the system is a system on a chip (SOC).

14. A hard disk drive comprising:

an internal oscillator;

a system clock;

a motor controller coupled with the system clock, the motor controller including calibration circuitry configured to use the internal oscillator for a timing reference instead of the system clock when the system clock is not operating in accordance with an operating condition;

a head actuator configured to communicate with the motor controller; and

a spindle supply configured to provide emergency power to the calibration circuitry and the internal oscillator.

15. The hard disk drive of claim 14, wherein the calibration circuitry includes a register, and wherein the calibration circuitry is further configured to determine a calibration value using the internal oscillator and the system clock when the system clock is operating in accordance with the operating condition and store the calibration value in the register.

16. The hard disk drive of claim 14, wherein the motor controller is configured to use the internal oscillator as the timing reference to perform emergency parking.

17. The hard disk drive of claim 16, further comprising:

one or more platters;

wherein the motor controller is further configured to control the head actuator to prevent one or more heads coupled to the head actuator from landing on the one or more platters during emergency parking.

18. The hard disk drive of claim 14, wherein the motor controller includes the system clock.