Navigation sensor circuit and method

Abstract

A navigation sensor circuit and method includes monitoring a polling request signal transmitted from a microcontroller during a variable time interval, wherein the microcontroller is externally coupled to the navigation sensor circuit, calculating a polling return rate of the microcontroller based on the polling request signal, and dynamically adjusting a sensor frame rate of the navigation sensor circuit based on the polling return rate, wherein an image sensor of the navigation sensor circuit is operated to capture images to generate and output displacement data based on the sensor frame rate. The displacement data signal generated and returned by the image sensor is a valid signal to the microcontroller even when there are significant changes in the polling return rate of the microcontroller.

Description

Technical Field

[0001] This invention relates to a navigation sensor mechanism, and more particularly to a navigation sensor circuit and a corresponding method. Background Technology

[0002] Generally, a conventional optical mouse device may have a microcontroller (MCU) and an image sensor. The microcontroller periodically polls the image sensor, causing the image sensor to periodically report a displacement data signal. However, the polling rate of the microcontroller may actually be biased, so the image sensor may report more displacement signals in the time interval between two consecutive polling request events. In other words, some of the reported displacement signals are invalid. Summary of the Invention

[0003] Therefore, one of the objectives of this invention is to disclose a navigation sensor circuit and a corresponding method to solve the above-mentioned problems.

[0004] According to an embodiment of the present invention, a method for a navigation sensor circuit is disclosed. The method includes: monitoring a polling request signal sent from a microcontroller during a variable time interval, wherein the microcontroller is externally coupled to the navigation sensor circuit; calculating a polling return rate of the microcontroller based on the polling request signal; and dynamically adjusting a sensor frame rate of the navigation sensor circuit based on the polling return rate, wherein an image sensor of the navigation sensor circuit is operated to capture images to generate and output displacement data based on the sensor frame rate.

[0005] According to an embodiment of the present invention, a navigation sensor circuit externally coupled to a microcontroller is disclosed. The circuit includes an image sensor and a control circuit. The image sensor is used to operate and capture images to generate and output displacement data based on a sensor frame rate. The control circuit, coupled to the image sensor, is used to: monitor polling request signals sent from the microcontroller during variable time intervals; calculate the polling return rate of the microcontroller based on the polling request signals; and dynamically adjust the sensor frame rate based on the polling return rate.

[0006] According to an embodiment of the present invention, even when the polling rate of the microcontroller changes significantly, the displacement data signals generated and reported by the image sensor are valid signals for the microcontroller. Attached Figure Description

[0007] Figure 1 This is a block diagram of a navigation sensor circuit according to an embodiment of the present invention.

[0008] Figure 2 This is an embodiment of the present invention. Figure 1 The flowchart shown is an operation flowchart of the navigation sensor circuit (or control circuit).

[0009] Figure 3 This is a schematic diagram illustrating a first scenario example of the operation of a microcontroller and navigation sensor circuit according to an embodiment of the present invention.

[0010] Figure 4 This is a schematic diagram illustrating a second scenario example of the operation of a microcontroller and navigation sensor circuit according to an embodiment of the present invention.

[0011] Figure 5 This is a schematic diagram illustrating a third scenario example of the operation of a microcontroller and navigation sensor circuit according to an embodiment of the present invention.

[0012] The reference numerals in the attached figures are explained as follows:

[0013] Optical mouse device 100

[0014] Microcontroller 101

[0015] Navigation sensor circuit 102

[0016] Image sensor 103

[0017] Control circuit 104

[0018] Specific counter 105 Detailed Implementation

[0019] This invention discloses a technical solution for tracking the polling rate of a microcontroller, adjusting the sensor frame rate of an image sensor in real time or dynamically, so that the displacement data signals generated and reported by the image sensor are valid signals for the microcontroller. The disclosed technical solution aims to ensure that, even when the polling rate of the microcontroller changes significantly, the image sensor generates and reports only one displacement data signal within a time interval between two consecutive polling request events. In a preferred embodiment, all displacement data signals reported by the image sensor are valid signals for the microcontroller.

[0020] Figure 1 This is a block diagram of a navigation sensor circuit 102 according to an embodiment of the present invention. The navigation sensor circuit 102 is, for example, a mouse sensor, externally connected to the microcontroller 101, and includes an image sensor 103, a control circuit 104, and a specific counter 105. For example, the navigation sensor circuit 102 can be used in conjunction with the microcontroller 101 to form an optical mouse device 100 (but is not limited thereto).

[0021] The image sensor 103 operates and captures images based on a variable or adjustable sensor frame rate (or sensor operating rate) to generate / output multiple displacement data (or frame data) signals. This variable or adjustable sensor frame rate can be dynamically controlled or adjusted by the control circuitry 104. For example, when at least one polling return rate becomes high, the length of the variable time interval can be shortened, allowing the control circuitry 104 to adjust the sensor frame rate at an earlier point in time when the polling return rate becomes higher or faster. In other embodiments, the length of the variable time interval is proportional to a programmable threshold, and a specific counter 105 is activated by the control circuitry 104 to count the number of times at least one polling request signal is received, and the control circuitry 104 resets the specific counter 105 when a count value of the specific counter 105 exceeds the programmable threshold.

[0022] The microcontroller 101 is used to periodically send multiple polling request signals to the navigation sensor circuit 102, and each polling request signal is used to instruct the navigation sensor circuit 102 to report a displacement / frame data signal to the microcontroller 101. For example, ideally, the microcontroller 101 will poll the navigation sensor circuit 102 at a specified or negotiated polling rate of, for example, 1 kHz, that is, ideally poll the navigation sensor circuit 102 every 1000 microseconds; however, this is not a limitation of the invention.

[0023] In practice, the polling return rate may have signal deviations, so the microcontroller 101 may poll the navigation sensor circuit 102 at different time periods / intervals under different conditions. For example, if the polling return rate has a deviation of one percent, the microcontroller 101 may poll the navigation sensor circuit 102 at a longer time period (e.g., 1010 microseconds) or a shorter time period (e.g., 990 microseconds) under different conditions. The time errors of different lengths of time periods will accumulate, causing two or more displacement data signals to be returned between two consecutive polling request signals from the microcontroller 101, resulting in a portion of the returned displacement data signals being invalid.

[0024] To address this issue, the navigation sensor circuit 102 can be used to track the polling rate of the microcontroller 101 and dynamically adjust its sensor frame rate based on changes in the polling rate. This ensures that even when there may be signal deviations in the actual polling rate, the navigation sensor circuit 102 can generate and report only one displacement / frame data signal (i.e., report / return valid displacement data) to the microcontroller 101, making all returned displacement / frame data signals valid.

[0025] In practical applications, the control circuit 104 is used to monitor at least one polling request signal issued by the microcontroller 101 within a variable time interval, calculate at least one polling return rate of the microcontroller 101 based on the at least one polling request signal, and dynamically adjust the sensor frame rate based on the at least one polling return rate. For example, the control circuit 104 can adjust the sensor frame rate in real time or dynamically according to multiple different operating conditions, which are related to the minimum requirements of one or more polling request signals sent from the microcontroller 101 and multiple polling events of the microcontroller 101. For example, when at least one polling return rate is higher than a currently used frame rate, the control circuit 104 can adjust the sensor frame rate from the currently used frame rate to a higher frame rate in real time, so that the sensor frame rate is higher than the at least one polling return rate. Furthermore, in other embodiments, when the count value of a particular counter 105 exceeds the programmable threshold, the control circuit 104 may adjust the sensor frame rate from a currently used frame rate to a lower frame rate, which is lower than the currently used frame rate but higher than at least one polling return rate. In this case, when the count value is not higher than the programmable threshold, the control circuit 104 will not adjust the sensor frame rate.

[0026] In other embodiments, the control circuit 104 maintains the sensor frame rate when the sensor frame rate is higher than the at least one polling return rate and the difference between the sensor frame rate and the at least one polling return rate is less than a specific threshold. In other embodiments, when the count value of the specific counter 105 becomes higher than the programmable threshold, the control circuit 104 can adjust the sensor frame rate by setting it to the largest (fastest) of at least one polling return rate; however, this is not a limitation of the invention. The sensor frame rate can also be set to the last calculated polling return rate or the second fastest polling return rate (but is not limited to this). In other embodiments, the control circuit 104 may determine whether to decrease or maintain the sensor frame rate only at the end of the variable time interval.

[0027] Figure 2 This is an embodiment of the present invention. Figure 1 The flowchart of the operation of the control circuit 104 is shown. If the same result can be achieved in general, it is not necessary to follow the flowchart exactly. Figure 2 The steps in the process shown are performed sequentially, and Figure 2 The steps shown do not necessarily have to be performed consecutively; other steps can be inserted into them. The detailed process steps are explained below:

[0028] Step S200: Begin;

[0029] Step S201: Monitor one or more polling request signals sent by the external microcontroller 101;

[0030] Step S202: Determine whether a request from the external microcontroller 101 has been triggered; if so, proceed to step S203; otherwise, return to step S201.

[0031] Step S203: When a polling request signal is received from the microcontroller, calculate the polling rate of the microcontroller 101 and simultaneously increment the count value of the specific counter 105 by 1;

[0032] Step S204: Determine whether the calculated polling return rate is higher than the sensor frame rate; if the calculated polling return rate is higher than the sensor frame rate, the process proceeds to step S205; otherwise, the process proceeds to step S206.

[0033] Step S205: Store the calculated polling return rate and reset the count value of the specific counter 105 to zero;

[0034] Step S206: Determine whether the count value of the specific counter 105 is greater than a programmable threshold; if it is greater than the programmable threshold, proceed to step S205; otherwise, proceed to step S201.

[0035] Step S207: Determine whether the polling return rate is higher than the sensor frame rate; if the calculated polling return rate is higher than the sensor frame rate, the process proceeds to step S208; otherwise, the process proceeds to step S209.

[0036] Step S208: Increase the frame rate of the sensor;

[0037] Step S209: Determine whether the calculated polling return rate is lower than the sensor frame rate; if the polling return rate is lower than the sensor frame rate, the process proceeds to step S210; otherwise, the process proceeds to step S211.

[0038] Step S210: Determine whether the calculated polling return rate is lower than the slower sensor frame rate used in the next round (i.e., the slower next-level frame rate); if the polling return rate is lower than the slower sensor frame rate, the process proceeds to step S212; otherwise, the process proceeds to step S211.

[0039] Step S211: Maintain the currently used sensor frame rate / operation rate; and

[0040] Step S212: Reduce the sensor frame rate / operation rate.

[0041] In step S201, the control circuit 104 (or the navigation sensor circuit 102) monitors or detects the reception of one or more polling request signals sent from the external microcontroller 101. In step S202, the control circuit 104 determines whether an event of receiving a polling request signal from the external microcontroller 101 has been triggered. If the event is not triggered, the control circuit 104 is arranged to continue monitoring the event in step S201. If the event is triggered, the control circuit 104 is arranged in step S203 to calculate a polling rate of the microcontroller 101 each time an event is triggered and to increment the count value of a specific counter 105 by 1. The count value of the specific counter 105 is initially set to zero.

[0042] In step S204, the control circuit 104 compares the calculated polling report rate with the currently used sensor frame rate. If the polling report rate is higher than the currently used sensor frame rate, the control circuit 104 stores or records the calculated polling report rate and resets the count value of the specific counter 105 to zero in step S205. If the polling report rate is not higher than the currently used sensor frame rate, the control circuit 104 compares the count value of the specific counter 105 with the programmable threshold in step S206. If the count value of the specific counter 105 is not higher than the programmable threshold, the process returns to step S201, and the control circuit 104 continues to monitor the signal reception event of the polling request signal. If the count value of the specific counter 105 is higher than the programmable threshold, the process proceeds to step S205, and the control circuit 104 stores or records the calculated polling report rate and resets the count value of the specific counter 105 to zero.

[0043] In steps S201-S205, the control circuit 104 monitors or detects whether a polling request signal is received. When the polling request signal is received, the control circuit 104 calculates the polling rate of the microcontroller 101 based on a time interval between the received polling request signal and a previously received polling request signal (e.g., two consecutive polling request signals). Furthermore, in this case, the control circuit 104 increments the count value of the specific counter 105 by 1. Then, in response to an event where the calculated polling rate becomes higher than the currently used sensor frame rate and / or an event where the count value of the specific counter 105 becomes higher than the programmable threshold, the control circuit 104 is configured to store the calculated polling rate and reset the count value of the specific counter 105 to zero. That is, when the calculated polling rate becomes higher than the currently used sensor frame rate, the control circuit 104 can immediately store the calculated polling rate and determine whether to adjust or maintain the sensor frame rate. Furthermore, whenever a time interval relating to (or proportional to) a certain value, the programmable threshold, or the polling return rate of the microcontroller 101 ends, the control circuit 104 can store the calculated polling return rate and then determine whether to adjust or maintain the sensor frame rate. Therefore, the control circuit 104 is capable of adjusting the sensor frame rate in real time and / or periodically adjusting the sensor frame rate based on a variable time interval that varies with a certain value, the programmable threshold, and / or the calculated polling return rate of the microcontroller 101.

[0044] In steps S207-S212, after determining that there might be a need to adjust the currently used sensor frame rate, the control circuit 104 further determines whether to adjust or maintain the sensor frame rate. In step S207, the control circuit 104 compares the calculated polling return rate with the sensor frame rate. If the calculated polling return rate is higher than the sensor frame rate, then in step S208, the control circuit 104 is configured to increase the sensor frame rate from the currently used frame rate to a higher frame rate, which could be a slightly higher frame rate. Once the sensor frame rate is adjusted, the process returns to step S201, and the control circuit 104 monitors the reception of the next polling request signal from the external microcontroller 101. Additionally, if the calculated polling return rate is not higher than the sensor frame rate, the control circuit 104 will determine in step S209 whether the calculated polling return rate is lower than the sensor frame rate. If the calculated polling return rate is neither higher nor lower than the sensor frame rate, it means that the calculated polling return rate is equal to the sensor frame rate. In this case, the control circuit 104 will maintain the currently used sensor frame rate in step S211 and will not adjust the frame rate. It should be noted that once the sensor frame rate is adjusted, the process returns to step S201 and the control circuit 104 monitors the reception of the next polling request signal from the external microcontroller 101. If the calculated polling report rate is lower than the sensor frame rate, in step S210, the control circuit 104 compares the calculated polling report rate with an adjusted lower frame rate (or a slightly lower frame rate). If the calculated polling report rate is lower than the adjusted lower frame rate, it indicates that the polling report rate of the microcontroller 101 has significantly decreased. In step S212, the control circuit 104 reduces the sensor frame rate from the currently used sensor frame rate to an adjusted lower frame rate that is still higher than the polling report rate of the microcontroller 101. If the calculated polling report rate is not lower than the adjusted lower frame rate, in step S211, the control circuit 104 maintains the sensor frame rate, ensuring that the currently used frame rate is higher than the polling report rate of the microcontroller 101.

[0045] In this way, even if the polling rate of the microcontroller 101 may be inaccurate, the control circuit 104 can still control the sensor frame rate to a value slightly higher than the polling rate of the microcontroller 101. This allows the navigation sensor circuit 102 to conserve power if the polling rate slows down and avoids reporting two or more displacement data to the microcontroller 101 between two adjacent / consecutive polling request events. Additionally, this also achieves the minimum polling rate requirement of the microcontroller 101. Once the polling rate becomes higher than the currently used frame rate, the navigation sensor circuit 102 can immediately increase the sensor frame rate and only slowly decrease it when a significant drop in the polling rate is ensured. Therefore, the minimum frame rate used by the image sensor 103 can be maintained at a value slightly higher than the polling rate of the microcontroller 101.

[0046] Figure 3 This is a schematic diagram illustrating a first scenario example of the operation of the microcontroller 101 and the navigation sensor circuit 102 according to an embodiment of the present invention. Figure 3 As shown, the microcontroller 101 is ideally configured to periodically send polling request events / signals at a period of 1000 microseconds. That is, the ideal polling rate of the microcontroller 101 is 1 kHz (but not limited to this), however, in practice the polling rate of the microcontroller 101 may have a deviation range of one percent (i.e., + / - 1%); this is not a limitation of the invention. In other words, in this example, the time interval between two consecutive polling request events can vary between 990 microseconds and 1010 microseconds. For example, due to such deviation, the microcontroller 101 may send multiple polling request events / signals at different periods such as 990 microseconds, 1000 microseconds, 1010 microseconds, and 990 microseconds under different conditions, such as... Figure 3As shown. The navigation sensor circuit 102 can control its sensor frame rate to be slightly higher than the polling rate currently used by the microcontroller 101 to track changes in the currently used polling rate. Therefore, equivalently, the navigation sensor circuit 102 can control the corresponding period of the sensor frame rate to be slightly shorter than the period of the currently used polling rate. For example, if the polling rate slows down at time t1, for example, the period of the polling rate changes from 990 microseconds to 1000 microseconds, then when the count value of the specific counter 105 becomes higher than the programmable threshold, the control circuit 104 can control the sensor frame rate to drop to a slower frame rate. And when the polling rate slows down further at time t2, for example, the period of the polling rate changes from 1000 microseconds to 1010 microseconds, then when the count value of the specific counter 105 again becomes higher than the programmable threshold, the control circuit 104 can control the sensor frame rate to drop to an even slower frame rate. When the polling rate becomes faster at time t3, for example, when the polling rate period changes from 1010 microseconds to 990 microseconds, the control circuit 104 can control the sensor frame rate to be shifted to a higher frame rate when the faster polling rate is detected.

[0047] Figure 4 This is a schematic diagram illustrating a second scenario example of the operation of the microcontroller 101 and navigation sensor circuit 102 according to an embodiment of the present invention. The programmable threshold can be set to 4 (but is not limited to), so that when the count value of the specific counter 105 reaches 5, the specific counter 105 will be reset. Figure 4In the example, at time t4, the specific counter 105 counts to 3, and the polling rate of the microcontroller 101 becomes 1020Hz, which is higher than the currently used sensor frame rate, such as 1000Hz, where the currently used sensor frame rate refers to the current sensor frame rate, representing the frame rate at which the image sensor 103 is currently operating. In this case, the control circuit 104 can immediately increase the sensor frame rate from 1000Hz to 1050Hz (e.g., the next higher frame rate). From time t4 to time t5, the polling rate of the microcontroller 101, for example, does not change, while the count value of the specific counter 105 will be higher than the programmable threshold (i.e., 4) at time t5. The sensor frame rate will be maintained at 1050Hz, and the control circuit 104 will use this to determine whether to increase, decrease, or maintain the sensor frame rate. During the time interval from time t4 to time t5, the polling rate of the microcontroller 101 is 1020Hz. Since the next slower frame rate is 1000Hz, which is lower than 1020Hz and does not meet the requirement for downgrading, the sensor frame rate will not drop to a lower frame rate. It should be noted that a polling rate lower than the current sensor frame rate may be higher than, equal to, or lower than the next slower frame rate. Therefore, the control circuit 104 will increase, decrease, or maintain the sensor frame rate based on different conditions.

[0048] Figure 5 This is a schematic diagram illustrating a third scenario example of the operation of the microcontroller 101 and navigation sensor circuit 102 according to another embodiment of the present invention. Figure 5As shown, the current sensor frame rate was originally maintained at 1000Hz, while a slightly lower frame rate, i.e., the next slower frame rate, is, for example, 950Hz. The polling rate of the microcontroller 101 may change, for example, it may be 800Hz, 780Hz, 810Hz, 910Hz, and 900Hz sequentially before time t6. Since none of these rates are higher than the currently used sensor frame rate (i.e., 1000Hz), a specific counter 105 will continue to count, and its count value will be greater than the programmable threshold (i.e., 4) at time t6. In this case, if the next slower frame rate is still faster than a maximum polling rate, the control circuit 104 will be configured to allow the sensor frame rate to drop to a slightly lower frame rate (i.e., the next slower frame rate). In practice, the control circuit 104 can search for the maximum / fastest polling rate among multiple polling rates corresponding to a time interval specified by the start and stop (i.e., reset) of the specific counter 105. For example, the control circuit 104 can select 910Hz as the maximum / fastest polling rate. Since the sensor frame rate to be changed, 950Hz, is still higher than the maximum / fastest polling rate of 910Hz, it can change the sensor frame rate from 1000Hz to 950Hz. From time t6 to time t7, since the polling rate does not become higher than 950Hz and the next slower frame rate is set at 910Hz, the sensor frame rate will be maintained at 950Hz. Similarly, the polling rate of the microcontroller 101 may change, possibly from time t6 to time t7, to 880Hz, 850Hz, 890Hz, 870Hz, and 840Hz respectively. Since none of the aforementioned rates exceed the currently used sensor frame rate (i.e., 950Hz), the specific counter 105 will count continuously and stop (i.e., reset) at time t7. In this case, if another slower frame rate is still faster than the maximum polling rate (e.g., 890Hz), the control circuit 104 will be configured to allow the current sensor frame rate to be downgraded to another slightly lower frame rate (i.e., the other slower frame rate, e.g., 910Hz). In practice, the control circuit 104 can search for the maximum / fastest polling rate among multiple polling rates corresponding to a time interval specified by the start and stop (i.e., reset) of the specific counter 105. For example, the control circuit 104 can select 890Hz and change the sensor frame rate from 950Hz to 910Hz, and the image sensor 103 will operate at a frame rate of 910Hz after time t7.

[0049] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for a navigation sensor circuit, characterized in that, include: During a variable time interval, a polling request signal sent from a microcontroller is monitored, wherein the microcontroller is externally coupled to the navigation sensor circuitry; Calculate the polling return rate of the microcontroller based on the polling request signal; as well as The sensor frame rate of the navigation sensor circuit is dynamically adjusted according to the polling return rate, wherein the image sensor of the navigation sensor circuit is operated to capture images to generate and output displacement data based on the sensor frame rate; The step of dynamically adjusting the sensor frame rate of the navigation sensor circuit based on the polling return rate includes: The length of the variable time interval is proportional to a programmable threshold, and a specific counter is used to count the number of times the polling request signal is received. When the count value of the specific counter is higher than the programmable threshold, the specific counter is reset, and the sensor frame rate is adjusted from the currently used frame rate to a lower frame rate. The lower frame rate is lower than the currently used frame rate but higher than the polling return rate.

2. The method as described in claim 1, characterized in that, The method further includes: When the polling return rate is higher than the currently used frame rate, the sensor frame rate is immediately adjusted from the currently used frame rate to a higher frame rate so that the sensor frame rate is higher than the polling return rate.

3. The method as described in claim 1, characterized in that, As the polling return rate becomes higher, the length of the variable time interval becomes shorter.

4. The method as described in claim 1, characterized in that, The method further includes: The sensor frame rate is not adjusted when the count value is not higher than the programmable threshold.

5. The method as described in claim 1, characterized in that, The method further includes: The sensor frame rate is maintained when the sensor frame rate is higher than the polling return rate and the difference between the sensor frame rate and the polling return rate is less than a specific threshold.

6. The method as described in claim 1, characterized in that, The method further includes: The decision to reduce or maintain the sensor frame rate is made only at the end of the variable time interval.

7. A navigation sensor circuit externally coupled to a microcontroller, characterized in that, Including: An image sensor is used to manipulate and capture images to generate and output displacement data based on the sensor frame rate; and A control circuit, coupled to the image sensor, is used to: During the variable time interval, the polling request signals sent from the microcontroller are monitored; Calculate the polling return rate of the microcontroller based on the polling request signal; as well as The sensor frame rate is dynamically adjusted based on the polling return rate. The step of dynamically adjusting the sensor frame rate based on the polling return rate includes: The duration of the variable time interval is proportional to a programmable threshold, and the navigation sensor circuit further includes a specific counter activated by the control circuit. The specific counter is used to count the number of times the polling request signal is received. When the count value of the specific counter is higher than the programmable threshold, the control circuit resets the specific counter and adjusts the sensor frame rate from the currently used frame rate to a lower frame rate, which is lower than the currently used frame rate but higher than the polling return rate.

8. The navigation sensor circuit as described in claim 7, characterized in that, The control circuit is configured to: When the polling return rate is higher than the currently used frame rate, the sensor frame rate is immediately adjusted from the currently used frame rate to a higher frame rate so that the sensor frame rate is higher than the polling return rate.

9. The navigation sensor circuit as described in claim 7, characterized in that, As the polling return rate becomes higher, the length of the variable time interval becomes shorter.

10. The navigation sensor circuit as described in claim 7, characterized in that, The control circuit is configured to: The sensor frame rate is not adjusted when the count value is not higher than the programmable threshold.

11. The navigation sensor circuit as described in claim 7, characterized in that, The control circuit is configured to: The sensor frame rate is maintained when the sensor frame rate is higher than the polling return rate and the difference between the sensor frame rate and the polling return rate is less than a specific threshold.

12. The navigation sensor circuit as described in claim 7, characterized in that, The control circuit is configured to: The decision to reduce or maintain the sensor frame rate is made only at the end of the variable time interval.

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