System and Method for Capturing an Event in MEMS Inertial Sensors

• US 20090240462A1
• Filed: 03/20/2009
• Published: 09/24/2009
• Est. Priority Date: 03/21/2008
• Status: Abandoned Application

• Current Assignee: Analog Devices, Inc.
• Original Assignee: Analog Devices, Inc.
• Inventors: Lee, James M.
• Application Number:
  US12/408,532
• Publication Number:
  US 20090240462A1
• Time in Patent Office: Days
• US Class Current: 702/141
• CPC Class Codes: G01P 1/127 for acceleration values
• CPC Class Codes: G01P 15/0891 with indication of predetermined acceleration values G01P15/135 takes precedence
• CPC Class Codes: G01P 15/18 in two or more dimensions
• CPC Class Codes: G11B 19/043 by detecting a free-fall condition

Abstract

A method of capturing an event in a MEMS accelerometer stores acceleration data in memory, detects a trigger event based on the acceleration data, and modifies a configuration of the memory so that a specified amount of the acceleration data is saved. A MEMS event capturing system includes an inertial sensor having sensor circuitry and event capturing circuitry implemented with the sensor circuitry. The event capturing circuitry includes memory capable of storing acceleration data received from the inertial sensor and a detection module operatively coupled with the memory that detects a trigger event. The event capturing circuitry also includes a management module operatively coupled with the memory and the detection module that modifies the memory'"'"'s storage configuration when the trigger event is detected.

Claims

1. A method of capturing an event in a MEMS accelerometer, the method comprising:

storing acceleration data in memory;

detecting a trigger event based on the acceleration data; and

modifying a configuration of the memory so that a specified amount of the acceleration data is saved.

2. The method of claim 1, wherein the specified amount of the acceleration data includes acceleration data stored before the detected trigger event.

3. The method of claim 1, further comprising:

processing the specified amount of the acceleration data in order to recognize the event.

4. The method of claim 3, wherein the event is a gesture.

5. The method of claim 1, wherein modifying a configuration of the memory includes varying an amount of the acceleration data stored.

6. The method of claim 1, wherein modifying a configuration of the memory includes modifying the configuration from a stream buffer to a first-in-first-out buffer.

7. The method of claim 1, wherein detecting a trigger event further comprises:

capturing an acceleration bias;

measuring acceleration at a predetermined period of time;

calculating a change in acceleration using the measured acceleration and the acceleration bias; and

comparing the change in acceleration to a threshold to detect the trigger event.

8. A MEMS event capturing system comprising:

an inertial sensor having sensor circuitry; and

event capturing circuitry implemented with the sensor circuitry, the event capturing circuitry including;

memory capable of storing acceleration data received from the inertial sensor;

a detection module operatively coupled with the memory that detects a trigger event; and

a management module operatively coupled with the memory and the detection module that modifies the memory'"'"'s storage configuration when the trigger event is detected.

9. The MEMS system of claim 8, wherein the memory'"'"'s storage configuration is modified from a stream buffer to a first-in-first-out buffer.

10. The MEMS system of claim 8, further comprising a microprocessor operatively coupled with the event capturing circuitry, the microprocessor capable of processing the acceleration data in order to recognize an event.

11. The MEMS system of claim 10, wherein the event is a gesture.

12. The MEMS system of claim 8, wherein the inertial sensor is formed on a die, and the sensor circuitry and event capturing circuitry are formed on or in the die.

13. The MEMS system of claim 8, wherein the sensor circuitry and event capturing circuitry are formed on or in a first die, and the inertial sensor is formed on or in a second die that is in communication with the first die.

14. The MEMS system of claim 8, wherein the inertial sensor includes an accelerometer or a gyroscope.

15. The MEMS system of claim 8, wherein the memory is capable of storing a fixed or a variable amount of acceleration data received from the inertial sensor.

16. A computer program product for capturing an event in a MEMS accelerometer, the computer program product comprising a computer usable medium having computer readable program code thereon, the computer readable program code comprising:

program code for storing acceleration data in memory;

program code for detecting a trigger event based on the acceleration data; and

program code for modifying a configuration of the memory so that a specified amount of the acceleration data is saved.

17. The computer program product of claim 16, wherein the specified amount of the acceleration data includes acceleration data stored before the detected trigger event.

18. The computer program product of claim 16, wherein the computer readable program code further comprises:

program code for processing the specified amount of the acceleration data in order to recognize the event.

19. The computer program product of claim 16, wherein the computer readable program code for modifying a configuration of the memory includes program code for varying an amount of the acceleration data stored.

20. The computer program product of claim 16, wherein the computer readable program code for modifying a configuration of the memory includes program code for modifying the configuration from a stream buffer to a first-in-first-out buffer.