System and method for MEMS sensor system synchronization

• US 10,180,340 B2
• Filed: 10/09/2014
• Issued: 01/15/2019
• Est. Priority Date: 10/09/2014
• Status: Active Grant

• Current Assignee: Invensense Incorporated (TDK Corporation)
• Original Assignee: Invensense Incorporated (TDK Corporation)
• Inventors: Milota, Andy, Lim, James, Keal, William Kerry
• Primary Examiner(s): Barbee, Manuel L
• Assistant Examiner(s): NIMOX, RAYMOND LONDALE
• Application Number:
  US14/510,224
• Publication Number:
  US 20160103002A1
• Time in Patent Office: 1,559 Days
• Field of Search: 702 89, 368 10
• CPC Class Codes: B81B 2201/0235 Accelerometers
• CPC Class Codes: B81B 2201/0242 Gyroscopes
• CPC Class Codes: B81B 2201/0292 Sensors not provided for in B81B2201/0207 - B81B2201/0285
• CPC Class Codes: B81B 2207/09 Packages
• CPC Class Codes: B81B 7/02 containing distinct electrical or optical devices of particular relevance for their function, e.g. microelectro-mechanical systems [MEMS] B81B7/04 takes precedence
• CPC Class Codes: G01D 18/008 with calibration coefficients stored in memory
• CPC Class Codes: H03L 1/00 Stabilisation of generator output against variations of physical values, e.g. power supply
• CPC Class Codes: H03L 7/00 Automatic control of frequency or phase; Synchronisation

Abstract

Various aspects of this disclosure comprise systems and methods for synchronizing sensor data acquisition and/or output. For example, various aspects of this disclosure provide for achieving a desired level of timing accuracy in a MEMS sensor system, even in an implementation in which timer drift is substantial.

Claims

1. A system for modifying a sensor output data rate (ODR), the system comprising:

at least one module having a sensor outputting measurements and a processor operable to, at least;

during a first interval, acquire available sensor measurements and store the acquired sensor measurements at a regular target ODR with a target period T;

during a second interval, acquire and store a first sensor measurement at a first time;

receive an ODR sync signal;

in response to the received ODR sync signal, modify operation of the sensor in order to acquire and store a second sensor measurement at a second time that is different than the first time plus the target period T, wherein the second sensor measurement is acquired directly following the first sensor measurement.

2. The system of claim 1, wherein the at least one module is operable to generate an internal clock signal, and a delay between reception of the ODR sync signal and the acquisition and storage of the second sensor value is at least one cycle of the internal clock signal.

3. The system of claim 1, wherein the at least one module is operable to generate the ODR sync signal when an application is initiated.

4. The system of claim 3, wherein the application comprises a camera application.

5. The system of claim 1, wherein the at least one module is operable to:

determine when enhanced sensor synchronization is desired; and

in response to a determination that enhanced synchronization is desired, generate the ODR sync signal.

6. The system of claim 5, wherein the at least one module is operable to determine when enhanced sensor synchronization is desired in response to a user input that corresponds to an activity that is associated with enhanced sensor synchronization.

7. The system of claim 6, wherein the activity comprises taking a photograph.

8. The system of claim 7, wherein the at least one module is operable to generate the ODR sync signal for image stabilization.

9. A system for modifying a sensor output data rate (ODR), the system comprising:

at least one module having a sensor outputting measurements and an internal sensor sync clock, wherein the module further comprises a processor operable to, at least;

receive a first sync signal from an external source;

receive a second sync signal from the external source;

determine, based at least in part on the internal sensor sync clock, a time differential between the received first sync signal and the received second sync signal;

determine an adjustment to the internal sensor sync clock based, at least in part, on the determined time differential and an expected time differential, wherein the output measurements are acquired and stored at an ODR established by the internal sensor sync clock; and

modify operation of the sensor by applying the determined adjustment to the ODR, so that subsequent sensor measurements are acquired at the adjusted ODR.

10. The system of claim 9, wherein the at least one module is operable to adjust a frequency of the internal sync clock and/or a divide-by value based, at least in part, on the determined adjustment.

11. The system of claim 9, wherein the at least one module is operable to perform the receive a first sync signal, the receive a second sync signal, the determine a time differential, and the determine an adjustment independently for a plurality of sensor circuits.

12. The system of claim 9, wherein the at least one module is operable to:

upon reception of the first sync signal, store a first counter value;

upon reception of the second sync signal, store a second counter value; and

determine the time differential between the first sync signal and the received second sync signal based, at least in part, on a difference between the first and second stored counter values.

13. The system of claim 9, wherein the at least one module is operable to receive information about the expected time differential from an external source.

14. The system of claim 9, wherein the at least one module is operable to generate the first and second sync signals when an application is initiated.

15. The system of claim 9, wherein the at least one module is operable to:

determine when enhanced sensor synchronization is desired; and

in response to a determination that enhanced synchronization is desired, generate the first and second sync signals.

16. The system of claim 9, wherein the at least one module operates to generate the first and second sync signals for image stabilization.

17. A system for modifying a sensor output data rate (ODR), the system comprising:

at least one module having a sensor circuit outputting measurements and a clock circuit, wherein the module further comprises a processor operable to, at least;

first communicate a first sync signal to the sensor circuit;

after said first communicate, receive a first counter value from the sensor circuit;

second communicate a second sync signal to the sensor circuit;

after said second communicate, receive a second counter value from the sensor circuit;

determine, based at least in part on the first and second counter values from the sensor circuit, an adjustment to the clock circuit of the sensor circuit;

communicate information of the determined adjustment of the clock circuit to the sensor circuit, wherein the sensor measurements are acquired and stored at an ODR established by the clock circuit; and

modify operation of the sensor by applying the determined adjustment to the ODR, so that subsequent sensor measurements are acquired at the adjusted ODR.

18. The system of claim 17, wherein the at least one module is operable to:

determine a difference between the received first and second counter values;

compare the determined difference to an expected difference; and

determine the adjustment to the clock circuit of the sensor circuit based at least in part on the comparison.

19. The system of claim 17, wherein the determined adjustment to the clock circuit comprises an adjustment to clock frequency and/or a clock divide-by value.

20. The system of claim 17, wherein the at least one module is operable to perform the first communicate, the receive a first counter value, the second communicate, the receive a second counter value, the determine an adjustment, and the communicate information independently for a plurality of sensor circuits.

21. The system of claim 17, wherein the at least one module is operable to generate the first and second sync signals when an application is initiated.

22. The system of claim 17, wherein the at least one module is operable to:

determine when enhanced sensor synchronization is desired; and

in response to a determination that enhanced synchronization is desired, generate the first and second sync signals.

23. The system of claim 17, wherein the at least one module operates to generate the first and second sync signals for image stabilization.