# US 9,437,237 B1 · Method to detect power loss through data storage device spindle speed > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,437,237 B1 - Document ID: US9437237B1 - Status: Granted - Kind: B1 - Application number: 14/627,590 - Filed: 2015-02-20 - Granted: 2016-09-06 - Earliest claimed: 2015-02-20 - Assignees: Western Digital Technologies, Inc. - Applicants: Western Digital Technologies, Inc. - Inventors: Cheng Fatt Yee; Wei San Pang - Web page: https://patentgrep.com/patent/US9437237B1 ## CPC - G11B 19/28: Speed controlling, regulating, or indicating (G11B19/24 takes precedence) - G11B 19/048: {Testing of disk drives, e.g. to detect defects or prevent sudden failure} - G11B 19/20: Driving; Starting; Stopping; Control thereof - G11B 19/2054: {Spindle motor power-up sequences} - G11B 19/26: Speed-changing arrangements; Reversing arrangements; Drive-transfer means therefor - G11B 2220/90: Tape-like record carriers - G11B: INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER (recording measured values in a way that does not require playback through a transducer G01D9/00; recording or playback apparatus using mechanically marked tape, e.g. punched paper tape, or using unit records, e.g. punched or magnetically marked cards G06K; transferring data from one type of record carrier to another G06K1/18; circuits for coupling output of reproducer to radio receiver H04B1/20; gramophone pick-ups or like acoustic electromechanical transducers or circuits therefor H04R) ## Abstract A method for detecting power loss on a data storage device (DSD) includes: as part of a device initialization of the DSD, measuring a rotational speed of a spindle of a rotating media; comparing the measured spindle rotational speed to a threshold rotational speed value; and based on the comparison, determining whether the device initialization has been triggered due to a power-on reset of the DSD. ## Claims ### Claim 1 A method for detecting power loss on a data storage device (DSD), the method comprising: as part of a device initialization of the DSD, measuring a rotational speed of a spindle of a rotating media; comparing the measured spindle rotational speed to a threshold rotational speed value; and based on the comparison, determining whether the device initialization has been triggered due to a power-on reset of the DSD, wherein the method is performed under the control of a processor. ### Claim 2 (depends on 1) The method of claim 1, further comprising: in response to a determination that the measured spindle rotational speed is equal to or greater than the threshold rotational speed value, incrementing a count of a power-loss counter. ### Claim 3 (depends on 2) The method of claim 2, wherein the count of the power-loss counter is stored in nonvolatile storage. ### Claim 4 (depends on 2) The method of claim 2, wherein the count of the power-loss counter is stored on the rotating media. ### Claim 5 (depends on 1) The method of claim 1, further comprising: in response to a determination that the measured spindle rotational speed is less than the threshold rotational speed value, incrementing a count of a power-on reset counter. ### Claim 6 (depends on 1) The method of claim 1, wherein the threshold rotational speed value is based on a rotational speed difference from an operational rotational speed of the spindle. ### Claim 7 (depends on 1) The method of claim 1, wherein the threshold rotational speed value is adjustable. ### Claim 8 A data storage device (DSD), comprising: rotating media; a spindle configured to cause the rotating media to rotate; a rotational speed sensor configured to sense a rotational speed of the spindle as part of a device initialization of the DSD; a power-loss counter configured to count power-loss events; and a control unit configured to: determine the rotational speed of the spindle based on a signal from the rotational speed sensor; compare the determined rotational speed of the spindle to a threshold rotational speed value; and based on the comparison, determine whether the device initialization has been triggered due to a power-on reset of the DSD. ### Claim 9 (depends on 8) The DSD of claim 8, wherein in response to a determination that the spindle rotational speed is equal to or greater than the threshold rotational speed value, the control unit is further configured to increment a count of the power-loss counter. ### Claim 10 (depends on 9) The DSD of claim 9, further comprising: nonvolatile storage, wherein the control unit is further configured to store the count of the power-loss counter in the nonvolatile storage. ### Claim 11 (depends on 9) The DSD of claim 9, wherein the control unit is further configured to store the count of the power-loss counter on the rotating media. ### Claim 12 (depends on 8) The DSD of claim 8, further comprising: a power-on reset counter, wherein in response to a determination that the spindle rotational speed is less than the threshold rotational speed value, the control unit is further configured to increment a count of the power-on reset counter. ### Claim 13 A non-transitory computer readable medium having stored therein a program for making a processor execute a method for detecting power loss on a data storage device (DSD), said program including executable instructions for performing operations comprising: as part of a device initialization of the DSD, measuring by the processor a rotational speed of a spindle of a rotating media; comparing by the processor the measured spindle rotational speed to a threshold rotational speed value; and based on the comparison, determining by the processor whether the device initialization has been triggered due to a power-on reset of the DSD. ### Claim 14 (depends on 13) The non-transitory computer readable medium having stored therein a program as defined in claim 13, the program further comprising executable instructions for performing operations including: in response to a determination that the spindle rotational speed is equal to or greater than the threshold rotational speed value, incrementing a count of a power-loss counter. ### Claim 15 (depends on 14) The non-transitory computer readable medium having stored therein a program as defined in claim 14, the program further comprising executable instructions for performing operations including: storing the count of the power-loss counter in nonvolatile storage. ### Claim 16 (depends on 14) The non-transitory computer readable medium having stored therein a program as defined in claim 14, the program further comprising executable instructions for performing operations including: storing the count of the power-loss counter on the rotating media. ### Claim 17 (depends on 13) The non-transitory computer readable medium having stored therein a program as defined in claim 13, the program further comprising executable instructions for performing operations including: in response to a determination that the spindle rotational speed is less than the threshold rotational speed value, incrementing a count of a power-on reset counter. ### Claim 18 (depends on 13) The non-transitory computer readable medium having stored therein a program as defined in claim 13, the program further comprising executable instructions for performing operations including: determining the threshold rotational speed value based on a rotational speed difference from an operational rotational speed of the spindle. ### Claim 19 An apparatus for detecting power loss duration on a data storage device (DSD), the apparatus comprising: a control unit configured to, as part of a device initialization of the DSD: measure a rotational speed of a spindle of a rotating media; compare the measured spindle rotational speed to a plurality of successively lower threshold rotational speed values corresponding to successively longer time durations; and determine a power loss duration based on comparisons of the measured spindle rotational speed with the plurality of successively lower threshold rotational speed values. ### Claim 20 (depends on 19) The apparatus of claim 19, wherein the control unit is further configured to: in response to a determination that the measured spindle rotational speed is greater than one of the successively lower threshold rotational speed values: store a time duration corresponding to an immediately preceding threshold rotational speed value as a power loss duration, and increment a count of a power-loss counter. ### Claim 21 (depends on 20) The apparatus of claim 20, wherein the control unit is further configured to store the count of the power-loss counter in nonvolatile storage. ### Claim 22 (depends on 20) The apparatus of claim 20, wherein the control unit is further configured to store the count of the power-loss counter on the rotating media. ### Claim 23 (depends on 19) The apparatus of claim 19, wherein the control unit is further configured to: in response to a determination that the measured spindle rotational speed is less than a minimum threshold rotational speed value, incrementing a count of a power-on reset counter. ### Claim 24 (depends on 19) The apparatus of claim 19, wherein the successively lower threshold rotational speed values are based on rotational speed differences from an operational rotational speed of the spindle.