Differential MEMS device and methods
A MEMS device includes a first MEMS sensor associated with a first spatial plane and a second MEMS sensor is associated with a spatial second plane not co-planar with the first spatial plane, wherein the first MEMS sensor is configured to provide a first interrupt and a first data in response to a physical perturbation, wherein the second MEMS sensor is configured to provide a second interrupt and second data in response to the physical perturbation, and a controller configured to receive the first interrupt at a first time and the second interrupt at a second time different from the first time, wherein the controller is configured to determine a latency between the first time and the second time, and wherein the controller is configured to determine motion data in response to the first data, to the second data, and to the latency.
1. A sensor device comprising:
an initialization unit configured to output a first initialization signal and a second initialization signal, in response to a master initialization signal;
a plurality of tri-axis MEMS sensors coupled to the initialization unit, wherein the plurality of tri-axis MEMS sensors comprises a first tri-axis MEMS sensor and a second tri-axis MEMS sensor, wherein the first tri-axis MEMS sensor is associated with a first spatial plane, wherein the second tri-axis MEMS sensor is associated with a spatial second plane, wherein the first spatial plane and the second spatial plane are not co-planar, wherein the first tri-axis MEMS sensor is configured to provide a first set of data in response to a physical perturbation, wherein the second tri-axis MEMS sensor is configured to provide a second set of data in response to the physical perturbation, wherein the first tri-axis MEMS sensor is configured to provide a first reply in response to the first initialization signal, wherein the second tri-axis MEMS sensor is configured to provide a second reply in response to the second initialization signal; and
a controller coupled to the initialization unit and to the plurality of tri-axis MEMS sensors, wherein the controller is configured to provide the master initiation signal to the initialization unit, wherein the controller is configured to receive the first reply at a first time period, wherein the controller is configured to receive the second reply at a second time period, wherein the first time period and the second time period need not be identical, wherein the controller is configured to determine a latency between the first time period and the second time period, wherein the controller is configured to receive the first set of data and the second set of data, and wherein the controller is configured to synchronize the first set of data and the second set of data to form motion data in response to the latency.
2. The sensor device of claim 1 wherein the plurality of tri-axis MEMS sensors each comprise a single type of MEMS sensor, wherein the single type of MEMS sensor is selected from a group consisting of: an accelerometer, a gyroscope, a magnetometer.
3. The sensor device of claim 1
wherein the first spatial plane and the second spatial plane are parallel;
wherein the first set of data and the second set of data form differential data; and
wherein the controller is configured to determine motion data in response to the differential data and to the latency.
4. The sensor device of claim 1 wherein the first spatial plane and the second spatial plane are orthogonal.
5. The sensor device of claim 1 wherein the first tri-axis MEMS sensor comprises a self-test circuit configured to perform a self-test in response to the first initialization signal.
6. The sensor device of claim 5
wherein the self-test circuit is configured to provide a self-test physical perturbation to the first tri-axis MEMS sensor in response to the first initialization signal; and
wherein the first tri-axis MEMS sensor is configured to provide the first reply in response to the self-test physical perturbation.
7. The sensor device of claim 1
wherein the motion data is characterized by a first noise factor;
wherein the first set of data is characterized by a second noise factor; and
wherein the first noise factor is smaller than the second noise factor.
8. A sensor device comprising:
a plurality of tri-axis MEMS sensors comprising a first tri-axis MEMS sensor and a second tri-axis MEMS sensor, wherein the first tri-axis MEMS sensor is associated with a first spatial plane, wherein the second tri-axis MEMS sensor is associated with a spatial second plane, wherein the first spatial plane and the second spatial plane are not co-planar, wherein the first tri-axis MEMS sensor is configured to provide a first interrupt in response to a physical perturbation, wherein the first tri-axis MEMS sensor is also configured to provide a first set of data in response to the physical perturbation, wherein the second tri-axis MEMS sensor is configured to provide a second interrupt in response to the physical perturbation, wherein the second tri-axis MEMS sensor is also configured to provide a second set of data in response to the physical perturbation; and
a controller coupled to the plurality of tri-axis MEMS sensors, wherein the controller is configured to receive the first interrupt at a first time period, wherein the controller is configured to receive the second interrupt at a second time period, wherein the first time period and the second time period need not be identical, wherein the controller is configured to determine a latency between the first time period and the second time period, wherein the controller is configured to receive the first set of data and the second set of data, wherein the controller is configured to synchronize the first set of data to the second set of data to form motion data in response to the latency.
9. The sensor device of claim 8 wherein the plurality of tri-axis MEMS sensors comprises a single type of MEMS sensor, wherein the single type of MEMS sensor is selected from a group consisting of: an accelerometer, a gyroscope, a magnetometer.
10. The sensor device of claim 8
wherein the first spatial plane and the second spatial plane are parallel;
wherein the first set of data and the second set of data form differential data; and
wherein the controller is configured to determine motion data in response to the differential data and to the latency.
11. The sensor device of claim 8 wherein the first spatial plane and the second spatial plane are orthogonal.
12. The sensor device of claim 8 wherein the plurality of tri-axis MEMS devices are coupled to the controller via a serial bus.
13. The sensor device of claim 8
wherein the first tri-axis MEMS device is operated at a first frequency;
wherein the second tri-axis MEMS device is operated at a second frequency; and
wherein the first frequency and the second frequency are different.
14. The sensor device of claim 8
wherein the controller is configured to receive the first set of data at a third time period and the second set of data at a fourth time period; and
wherein the controller is configured to synchronize the first set of data to the second set of data to form the motion data in response to the third time period, to the fourth time period and to the latency.
15. A method for a sensor device comprising:
simultaneously receiving in a first tri-axis MEMS sensor and a second tri-axis MEMS sensor an initialization signal, wherein the first tri-axis MEMS sensor is associated with a first spatial plane, wherein the second tri-axis MEMS sensor is associated with a spatial second plane, wherein the first spatial plane and the second spatial plane are not co-planar;
outputting from the first tri-axis MEMS sensor a first reply in response to the initialization signal;
outputting from the second tri-axis MEMS sensor a second reply in response to the initialization signal;
receiving in a controller the first reply at a first time period;
receiving in the controller the second reply at a second time period, wherein the first time period and the second time period need not be identical;
determining in the controller, a latency between the first time period and the second time period;
outputting from the first tri-axis MEMS sensor a first set of data in response to a physical perturbation;
outputting from the second tri-axis MEMS sensor a second set of data in response to the physical perturbation;
receiving in the controller the first set of data at a third time period;
receiving in the controller the second set of data at a fourth time period; and
synchronizing in the controller the first set of data to the second set of data to form motion data in response to the third time period, to the fourth time period and to the latency.
16. The method of claim 15 wherein the first reply and the second reply are selected from a group consisting of: accelerometer data, gyroscope rotational data, and magnetic data.
17. The method of claim 15 wherein the first spatial plane and the second spatial plane are orthogonal.
18. The method of claim 15
wherein the first spatial plane and the second spatial plane are parallel; and
wherein the method further comprises:
determining in the controller differential data in response to the first set of data and the second set of data; and
wherein the determining in the controller motion data comprises determining in the controller motion data in response to the differential data.
19. The method of claim 15
wherein the initialization signal comprises a self-test command; and
wherein the outputting from the first tri-axis MEMS sensor the first reply comprises outputting from the first tri-axis MEMS sensor a self-test response in response to the self-test command.
20. The method of claim 19 wherein the outputting from the first tri-axis MEMS sensor the self-test response comprises:
providing in the first tri-axis MEMS sensor a self-test physical perturbation; and
determining the self-test response in response to the self-test perturbation.