Spread spectrum sensor scanning using resistive-inductive-capacitive sensors
A system may include at least one resistive-inductive-capacitive sensor and a control circuit configured to maintain timing parameters for operation of the at least one resistive-inductive-capacitive sensor and vary at least one of the timing parameters to control a spectrum associated with the at least one resistive-inductive-capacitive sensor, wherein the spectrum comprises one of a sensor activity spectrum of the at least one resistive-inductive-capacitive sensor and a current usage spectrum associated with electrical current delivered to the at least one resistive-inductive-capacitive sensor from a source of electrical energy.
1. A system comprising:
at least one resistive-inductive-capacitive sensor in electrical communication with a human-machine interface such that human interaction with the human-machine interface causes a displacement in a mechanical member of the human-machine interface which in turn causes variance in an impedance of the at least one resistive-inductive-capacitive sensor; and
a control circuit configured to:
maintain timing parameters for operation of the at least one resistive-inductive-capacitive sensor; and
vary at least one of the timing parameters to control a spectrum associated with the at least one resistive-inductive-capacitive sensor, wherein the spectrum comprises one of a sensor activity spectrum of the at least one resistive-inductive-capacitive sensor and a current usage spectrum associated with electrical current delivered to the at least one resistive-inductive-capacitive sensor from a source of electrical energy.
2. The system of claim 1 , wherein the timing parameters comprise at least one of:
an order in which the at least one resistive-inductive-capacitive sensor is scanned during a scan period;
a time between successive observations of two resistive-inductive-capacitive sensors of the at least one resistive-inductive-capacitive sensor;
a time between successive observations of particular resistive-inductive-capacitive sensors; and
a duration within the scan period for observing a particular resistive-inductive-capacitive sensor of the at least one resistive-inductive-capacitive sensor.
3. The system of claim 1 , wherein within the duration within the scan period for observing a particular resistive-inductive-capacitive sensor of the at least one resistive-inductive-capacitive sensor, a driving signal for driving the at least one resistive-inductive-capacitive sensor is increased from a beginning of the duration to a maximum drive strength and decreased from the maximum drive strength until an end of the duration.
4. The system of claim 1 , wherein the control circuit is configured to randomly vary at least one of the timing parameters.
5. The system of claim 1 , wherein the control circuit is configured to pseudo-randomly vary at least one of the timing parameters.
6. The system of claim 1 , wherein the control circuit is configured to pseudo-randomly vary at least one of the timing parameters using a linear-feedback shift register.
7. The system of claim 1 , wherein the control circuit is configured to vary at least one of the timing parameters in accordance with a fixed repeating pattern.
8. The system of claim 1 , wherein the timing parameters comprise at least one of a presence, duration, and position of an unused slot in which none of the at least one resistive-inductive-capacitive sensors is active.
9. The system of claim 1 , further comprising:
a driver configured to drive the at least one resistive-inductive-capacitive sensor at a driving frequency;
a measurement circuit communicatively coupled to the at least one resistive-inductive-capacitive sensor and configured to:
measure phase information associated with the at least one resistive-inductive-capacitive sensor; and
based on the phase information, determine a displacement of a mechanical member relative to the at least one resistive-inductive-capacitive sensor, wherein the displacement of the mechanical member causes a change in an impedance of the at least one resistive-inductive-capacitive sensor.
10. The system of claim 9 , wherein the at least one resistive-inductive-capacitive sensor comprises a plurality of resistive-inductive-capacitive sensors, and the control circuit is configured to maintain the timing parameters in order to:
time-division multiplex drive the plurality of resistive-inductive-capacitive sensors; and
time-division multiplex measure by the measurement circuit the phase information associated with each of the plurality of resistive-inductive-capacitive sensors.
11. A method comprising:
maintaining timing parameters for operation of at least one resistive-inductive-capacitive sensor in electrical communication with a human-machine interface such that human interaction with the human-machine interface causes a displacement in a mechanical member of the human-machine interface which in turn causes variance in an impedance of the at least one resistive-inductive-capacitive sensor; and
varying at least one of the timing parameters to control a spectrum associated with the at least one resistive-inductive-capacitive sensor, wherein the spectrum comprises one of a sensor activity spectrum of the at least one resistive-inductive-capacitive sensor and a current usage spectrum associated with electrical current delivered to the at least one resistive-inductive-capacitive sensor from a source of electrical energy.
12. The method of claim 11 , wherein the timing parameters comprise at least one of:
an order in which the at least one resistive-inductive-capacitive sensor is scanned during a scan period;
a time between successive observations of two resistive-inductive-capacitive sensors of the at least one resistive-inductive-capacitive sensor;
a time between successive observations of particular resistive-inductive-capacitive sensors; and
a duration within the scan period for observing a particular resistive-inductive-capacitive sensor of the at least one resistive-inductive-capacitive sensor.
13. The method of claim 11 , wherein within the duration within the scan period for observing a particular resistive-inductive-capacitive sensor of the at least one resistive-inductive-capacitive sensor, a driving signal for driving the at least one resistive-inductive-capacitive sensor is increased from a beginning of the duration to a maximum drive strength and decreased from the maximum drive strength until an end of the duration.
14. The method of claim 11 , further comprising randomly varying at least one of the timing parameters.
15. The method of claim 11 , further comprising pseudo-randomly varying at least one of the timing parameters.
16. The method of claim 11 , further comprising pseudo-randomly varying at least one of the timing parameters using a linear-feedback shift register.
17. The method of claim 11 , further comprising varying at least one of the timing parameters in accordance with a fixed repeating pattern.
18. The method of claim 11 , wherein the timing parameters comprise at least one of a presence, duration, and position of an unused slot in which none of the at least one resistive-inductive-capacitive sensors is active.
19. The method of claim 11 , further comprising:
driving the at least one resistive-inductive-capacitive sensor at a driving frequency;
measuring phase information associated with the at least one resistive-inductive-capacitive sensor; and
based on the phase information, determining a displacement of a mechanical member relative to the at least one resistive-inductive-capacitive sensor, wherein the displacement of the mechanical member causes a change in an impedance of the at least one resistive-inductive-capacitive sensor.
20. The method of claim 19 , wherein the at least one resistive-inductive-capacitive sensor comprises a plurality of resistive-inductive-capacitive sensors, and the method further comprises maintaining the timing parameters in order to:
time-division multiplex drive the plurality of resistive-inductive-capacitive sensors; and
time-division multiplex measure by the measurement circuit the phase information associated with each of the plurality of resistive-inductive-capacitive sensors.
21. A host device comprising:
an enclosure;
a human-machine interface;
a resonant phase sensing system integral to the enclosure and comprising:
at least one resistive-inductive-capacitive sensor in electrical communication with the human-machine interface such that human interaction with the human-machine interface causes a displacement in a mechanical member of the human-machine interface which in turn causes variance in an impedance of the at least one resistive-inductive-capacitive sensor; and
a driver configured to drive the at least one resistive-inductive-capacitive sensor with a driving signal at a driving frequency; and
a control circuit configured to:
maintain timing parameters for operation of the at least one resistive-inductive-capacitive sensor; and
vary at least one of the timing parameters to control a spectrum associated with the at least one resistive-inductive-capacitive sensor, wherein the spectrum comprises one of a sensor activity spectrum of the at least one resistive-inductive-capacitive sensor and a current usage spectrum associated with electrical current delivered to the at least one resistive-inductive-capacitive sensor from a source of electrical energy.