CN109990895B - Infrared receiving system for inhibiting ambient light interference and SOC chip - Google Patents
Infrared receiving system for inhibiting ambient light interference and SOC chip Download PDFInfo
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Abstract
The invention discloses an infrared receiving system and an SOC chip for inhibiting ambient light interference, wherein the infrared receiving system comprises an infrared receiver, an ADC converter, a digital filter and a resistance switching module; the signal input end of the ADC converter is connected with the signal output end of the infrared receiver; the sampling input end of the digital filter is connected with the signal output end of the ADC converter, the signal output end of the resistance switching module is connected with the signal output end of the infrared receiver, and the control input end of the resistance switching module is connected with the signal output end of the digital filter. The SOC chip is connected with an external infrared receiver, integrates a burr filtering module, an ADC (analog-to-digital converter), a digital filter and a resistance switching module, and the selectable resistance value inside the resistance switching module is matched with different light intensities. The invention automatically gates the pull-up resistor with the matching resistance value by means of the same circuit system so as to adapt to executing normal infrared detection function in ambient light with various intensities.
Description
Technical Field
The invention belongs to the technical field of photoelectric detection, and particularly relates to an infrared receiving system for inhibiting ambient light interference and an SOC (system on chip).
Background
At present, an infrared transmitting tube and an infrared receiving tube are often used for distance detection or obstacle avoidance, the infrared transmitting tube and the infrared receiving tube can process effective optical signals of working wave bands near 940nm, and because the ambient light generally comprises sunlight which also comprises optical signals of the working wave bands, the detection of the infrared receiving tube is greatly influenced by the interference of the ambient light.
The prior infrared detection circuit generally comprises an infrared transmitting tube, an infrared receiving tube and an MCU with an internal ADC module, wherein the MCU controls the infrared transmitting tube to modulate and transmit an infrared modulation signal with a preset duty ratio, receives a reflection signal of the infrared modulation signal through the infrared receiving tube, and samples the signal received by the infrared receiving tube through the ADC module in the MCU. Because the resistance parameter of the infrared detection circuit is fixed, the infrared receiving tube easily enters a saturated state in the strong light reflecting surface, and the sensitivity of the infrared receiving tube is weakened in the weak light reflecting surface. Therefore, the resistor with the same resistance value is difficult to support the same infrared detection circuit to complete a normal infrared detection mechanism under the two scenes of strong light and weak light.
If an infrared detection circuit is designed for each ambient light scene, the accuracy of infrared detection under each ambient light scene can be ensured, however, the design is complicated and complicated by adopting the mode, software intervention is needed, the hardware area of the circuit is increased, circuit components are increased, and the infrared detection efficiency is reduced.
Disclosure of Invention
In order to overcome the technical defects, the invention provides the following technical scheme:
the infrared receiving system for inhibiting the interference of ambient light comprises an infrared receiver, an ADC (analog-to-digital converter), a digital filter and a resistance switching module, wherein the infrared receiver is used for receiving infrared light signals of the external environment; the signal input end of the ADC converter is connected with the signal output end of the infrared receiver and is used for receiving the output signal of the infrared receiver and converting the output signal into a digital signal, and meanwhile, the signal output end of the ADC converter is used for outputting an infrared detection signal of the infrared receiving system; the sampling input end of the digital filter is connected with the signal output end of the ADC converter and is used for filtering the signal converted and output by the ADC converter; the control input end of the resistance switching module is connected with the signal output end of the digital filter and is used for gating a corresponding pull-up resistor to be connected between the signal output end of the infrared receiver and a power supply according to the amplitude value of the filtered signal output by the digital filter so as to realize the self-adaptive adjustment of the output signal of the infrared receiver; the signal output end of the resistance switching module is also connected with the signal output end of the infrared receiver, so that the ADC, the digital filter and the resistance switching module are connected to form a closed loop, and the sensitivity of the infrared receiver is adjusted by automatically switching resistors matched with the resistance value in the same infrared receiving system, so that the infrared receiving system is suitable for ground detection, wall detection or distance measurement under various intensity ambient light scenes, and the ambient light anti-interference capability of the infrared receiving system is improved.
Further, a burr filtering module is further arranged between the ADC converter and the infrared receiver, and the signal input end of the burr filtering module is connected with the signal output end of the infrared receiver and is used for filtering burr signals output by the infrared receiver; the burr filtering module is a first-order resistance-capacitance filter comprising a resistor and a capacitor. The technical scheme adopts a simple first-order resistance-capacitance filter to filter the interference of high-frequency noise.
Further, the ADC converter employs a Successive Approximation Register (SAR) analog-to-digital converter. The ADC converter provides an infrared detection digital signal which is easy to identify and process for the outside, and the technical scheme has the advantages of small occupied chip area and low cost under the condition of equal detection precision.
Further, the digital filter is a low pass filter. Thereby improving the reliability of the filtering.
Further, the resistance switching module comprises a configurable selector and a preset number of pull-up resistors; the configurable selector is provided with a preset number of signal input ends which are respectively connected with one end of the pull-up resistor with matched resistance values, the other end of the pull-up resistor is connected with the power supply, the selection output end of the configurable selector is connected with the signal output end of the infrared receiver, the selection end of the configurable selector is used as the control input end of the resistance switching module and is used for automatically switching the matched pull-up resistor to adjust the output signal of the infrared receiver according to the light intensity threshold value reached by the signal amplitude value output by the digital filter; wherein the light intensity threshold is a signal amplitude value preconfigured according to the light intensity received by the infrared receiver. Therefore, the sensitivity of the infrared receiver for receiving infrared modulation signals in various environmental light scenes is adjusted, environmental light interference with different intensities is restrained, and the efficiency and the accuracy of infrared detection are improved.
An SOC chip, one port of which is connected with a signal output end of an external infrared receiver, wherein the SOC chip integrates an ADC (analog-to-digital converter), a digital filter and a resistance switching module; the signal input end of the ADC converter is connected with the signal output end of the infrared receiver and is used for receiving the output signal of the infrared receiver and converting the output signal into a digital signal, and meanwhile, the signal output end of the ADC converter is used for outputting an infrared detection signal of the infrared receiving system; the sampling input end of the digital filter is connected with the signal output end of the ADC converter and is used for filtering the signal converted and output by the ADC converter; the control input end of the resistance switching module is connected with the signal output end of the digital filter and is used for gating a corresponding pull-up resistor to be connected between the signal output end of the infrared receiver and a power supply according to the amplitude value of the filtered signal output by the digital filter so as to realize the self-adaptive regulation of the output signal of the infrared receiver, wherein the power supply is a power supply configured in the SOC chip or a power supply connected with the power supply end of the SOC chip; the signal output end of the resistance switching module is also connected with the signal output end of the infrared receiver, so that the ADC converter, the digital filter and the resistance switching module are connected to form a closed loop. Compared with the prior art, the SOC chip improves the integration level of the circuits of the same type, integrates capacitance and resistance in the chip, and saves hardware cost.
Further, the SOC chip further comprises a burr filtering module, wherein a signal output end of the burr filtering module is connected with a signal input end of the ADC, and a signal input end of the burr filtering module is connected with a signal output end of the infrared receiver and is used for filtering burr signals output by the infrared receiver; the burr filtering module is a first-order resistance-capacitance filter comprising a resistor and a capacitor. The technical scheme adopts a simple first-order resistance-capacitance filter to filter the interference of high-frequency noise.
Further, the ADC converter employs a Successive Approximation Register (SAR) analog-to-digital converter. According to the technical scheme, under the condition of equal detection precision, the occupied chip area is small, and the cost is low.
Further, the digital filter is an IIR low-pass filter. Thereby improving the reliability of the filtering.
Further, the resistance switching module comprises a configurable selector and a preset number of pull-up resistors; the configurable selector is provided with a preset number of signal input ends which are respectively connected with one end of the pull-up resistor with matched resistance values, the other end of the pull-up resistor is connected with the power supply, the selection output end of the configurable selector is connected with the signal output end of the infrared receiver, the selection end of the configurable selector is used as the control input end of the resistance switching module and is used for automatically switching the matched pull-up resistor to adjust the output signal of the infrared receiver according to the light intensity threshold value reached by the signal amplitude value output by the digital filter; wherein the light intensity threshold is a signal amplitude value preconfigured according to the light intensity received by the infrared receiver. Therefore, the sensitivity of the infrared receiver for receiving infrared modulation signals in various environmental light scenes is adjusted, the environmental light interference of different intensities is restrained, the anti-interference capability of infrared detection environmental light is improved, and further the efficiency and the accuracy of infrared detection are improved.
Drawings
Fig. 1 is a schematic diagram of an infrared receiving system (excluding a spur filtering module) that suppresses ambient light interference.
Fig. 2 is a schematic diagram of an infrared receiving system (including a spur filtering module) that suppresses ambient light interference.
Fig. 3 is a schematic diagram of the internal structure of the SOC chip and its connection to the infrared receiver (excluding the spur filtering module).
Fig. 4 is a schematic diagram of the internal structure of the SOC chip and its connection to the infrared receiver (including the spur filtering module).
Detailed Description
The following describes the technical solution in the embodiment of the present invention in detail with reference to the drawings in the embodiment of the present invention.
Referring to fig. 1, an embodiment of the present invention provides an infrared receiving system for suppressing interference of ambient light, which is used for ground detection, wall detection or distance measurement in various types of ambient light scenes. The infrared receiving system comprises an infrared receiver and is used for receiving infrared light signals and infrared pulse signals of the external environment, and meanwhile, the infrared receiver also receives high-frequency noise containing interference frequency from the external environment. In this embodiment, the ambient light includes various types of ambient light signals such as sunlight with a large infrared light signal component, sunlight tube light, and bathroom warmer light; the infrared transmitting tube in the external environment modulates and transmits infrared pulse signals to the ground, the wall surface or the obstacle, and then the infrared pulse signals are received by the infrared receiver after being reflected by the ground, the wall surface or the obstacle, wherein the infrared pulse signals are modulated signals with preset frequency, and the infrared pulse signals are signals of an infrared transmission medium with the wavelength of 940 nm. Therefore, the infrared receiver outputs the infrared pulse signal with the preset frequency, high-frequency noise containing the interference frequency and the ambient light signal.
The infrared receiving system also comprises an ADC (analog-to-digital converter), a digital filter and a resistance switching module, wherein the signal input end of the ADC is connected with the signal output end of the infrared receiver and used for receiving and converting the electric signal output by the infrared receiver into a digital signal, and meanwhile, the signal output end of the ADC is used for outputting an infrared detection signal of the infrared receiving system, and the infrared detection signal can be a digital signal which is processed by the resistance switching module and the digital filter and is output or a digital signal which is output by the infrared receiver currently and obtained after analog-to-digital conversion. The sampling input end of the digital filter is connected to the signal output end of the ADC converter, and is used for filtering the signal converted and output by the ADC converter by setting the cut-off frequency. The control input end of the resistance switching module is connected with the signal output end of the digital filter, and the amplitude value of the filtered signal output by the digital filter is used for being transmitted to the resistance switching module to be used as the basis for switching the resistance parameters. The digital filter can screen out an ambient light signal as a basis for resistance switching, where the ambient light signal can be equivalent to ambient light, mainly an infrared light signal, that interferes with an infrared detection circuit in the prior art. The amplitude of the infrared light signal output by the digital filter changes along with the change of the ambient light intensity, so that the amplitude value of the signal transmitted to the resistance switching module changes in real time, and in order to avoid misjudgment, the resistance switching module needs to perform pull-up resistance switching of different resistance parameters so as to adapt to the current light intensity of the ambient light. Meanwhile, as the signal output end of the resistance switching module is connected with the signal output end of the infrared receiver, the arrangement of the digital filter can prevent the electric signal obtained by converting the high-frequency noise containing the interference frequency from being applied to the infrared receiver to generate additional current and fed back to the pull-up resistor in the resistance switching module so as to influence the sensitivity of the infrared receiver to infrared light, and finally, the detection signal output by the infrared receiving system is easy to cause erroneous judgment. The resistance switching module is internally provided with a plurality of pull-up resistors with different resistance values, and the pull-up resistors correspond to a plurality of preset light intensity thresholds and are respectively matched with signal amplitude values output by the digital filter under corresponding light intensity scenes, and the amplitude values corresponding to the light energy transmitted to the resistance switching module are changed based on the difference of the light signal intensities received by the infrared receiver, so that the pull-up resistors inside the resistance switching module are controlled to be changed.
When the signal amplitude value output by the digital filter reaches a light intensity threshold value, a pull-up resistor matched with the resistance value is selected to be conducted with an access circuit, so that the resistance switching module selects the pull-up resistor matched with the corresponding light intensity threshold value to be connected between the infrared receiver and a power supply according to the matching condition of the signal amplitude value output by the digital filter and the built-in light intensity threshold value, and accordingly the sensitivity of the infrared receiver for receiving infrared light is changed according to the resistance value of the connected pull-up resistor, and the sensitivity of the infrared receiver is adjusted by the resistance switching module through automatically switching the pull-up resistor matched with the resistance value, so that the output signal of the infrared receiver is adaptively adjusted; the signal output end of the resistance switching module is also connected with the signal output end of the infrared receiver, so that the ADC converter, the digital filter and the resistance switching module are connected to form a closed loop. The resistance value of the selectable pull-up resistor in the resistance switching module is matched with different light intensities, and when the ambient light intensity received by the infrared receiver is larger, the pull-up resistor gated in the resistance switching module is smaller; when the intensity of the ambient light received by the infrared receiver is smaller, the pull-up resistance gated by the resistance switching module is larger, so that the interference of the ambient light can be restrained.
Preferably, the ADC converter employs a Successive Approximation Register (SAR) analog-to-digital converter, which can also provide an infrared detection digital signal that is easy to identify and process for the outside, and compared with other ADC converters, the Successive Approximation Register (SAR) analog-to-digital converter occupies less chip area, has a high conversion rate, and has low hardware cost under the same detection precision.
Preferably, the digital filter may be implemented with a first-order IIR, a second-order IIR, an FIR or other type of digital low-pass filter, which is designed as an IIR low-pass filter or an FIR low-pass filter based on the frequency characteristics of the ambient light. The Infinite Impulse Response (IIR) filter is simple in structure, high in selectivity can be obtained by using a lower order number, used memory cells are few, calculated amount is small, and efficiency is high. Thereby improving the reliability of the filtering. The digital filter is disposed between the resistance switching module and the ADC converter, and is configured to filter the infrared pulse signal with the preset frequency and the high-frequency noise with the interference frequency, so as to output an ambient light signal, where it should be noted that the ambient light signal in this embodiment is a low-frequency infrared light signal. The signal output end of the digital filter is connected with the control input end of the resistance switching module, and the amplitude value of the filtered signal output by the digital filter is used as the basis for the resistance switching module to execute the switching resistance parameter. The digital filter can screen out the ambient light signal as the basis of resistance switching, and simultaneously based on the closed loop, the electric signal converted by the noise signal with higher frequency can be prevented from being applied to the infrared receiver to generate additional current, so that the voltage at two ends of the pull-up resistor in the resistance switching module is not in a normal state, and the sensitivity of the infrared receiver is influenced.
Preferably, as shown in fig. 1, the resistance switching module includes a configurable selector, and a preset number of pull-up resistors, such as R1, R2 … Rn; the configurable selector is provided with a preset number of signal input ends which are respectively connected with one ends of pull-up resistors with matched resistance values, the other ends of the pull-up resistors are connected with a power supply VCC, the function of adjusting the output voltage of the infrared receiver by pulling up is achieved, and the voltage can be pulled up to 3.3V in the embodiment; the selection output end of the configurable selector is connected with the signal output end of the infrared receiver, and the configurable selector controls the infrared receiver to adapt to light intensity change by switching and selecting proper pull-up resistors, namely, the sensitivity of the infrared receiver for receiving infrared light signals is adjusted under the action of the pull-up resistors in the resistance switching module, so that interference caused by ambient light is inhibited. The selection end of the configurable selector is used as the control input end of the resistance switching module, the control input end of the resistance switching module is connected with the signal output end of the digital filter, so that the configurable selector is controlled by the signal amplitude value of the signal output end of the digital filter, is configured to automatically switch the matched pull-up resistor into a closed loop formed by the ADC converter, the digital filter and the resistance switching module according to the light intensity threshold value reached by the signal amplitude value output by the digital filter, and the infrared detection result output by the ADC converter is identifiable by automatically configuring the pull-up resistor, and can exert a normal infrared detection mechanism under the current environment light intensity condition, including ground detection, wall detection, infrared ranging, obstacle avoidance and the like.
In this embodiment, the configurable selector is further configured with a light intensity threshold that matches the resistance of the pull-up resistor. The pull-up resistor R1 corresponds to the light intensity threshold E1, the pull-up resistor R2 corresponds to the light intensity threshold E2, the pull-up resistor Rn corresponds to the light intensity threshold En, if R1 is larger than R2 and R2 is larger than Rn, E1 is smaller than E2 and E2 is smaller than En, for example, when the light intensity of an infrared light signal is changed from E1 to E2, the resistance switching module controls the original pull-up resistor R1 to be selectively switched to the pull-up resistor R2 according to the signal amplitude value input by the selection end of the configurable selector, so that the pull-up effect of the output end of the infrared receiver is changed, and the infrared receiver can be changed from a saturated state to an unsaturated state so as to adapt to the interference brought by the current strong light environment. Therefore, the electric signal converted by the infrared receiver is effectively regulated, and the sensitivity of the infrared receiver to infrared signals is regulated so as to realize the adaptation of the infrared receiver to the light intensity variation; the light intensity threshold is a signal amplitude value which is preconfigured according to the light intensity received by the infrared receiver, so that the sensitivity of the infrared receiver for receiving infrared modulation signals in various types of ambient light scenes is adjusted, the ambient light interference of different intensities is restrained, and the ambient light anti-interference capability of the infrared receiving system is improved.
In the foregoing embodiment, after detecting the last output signal of the infrared receiver, the infrared receiving system obtains the current infrared detection signal through adaptive adjustment of the resistor, and outputs the current infrared detection signal through the signal output end of the ADC converter. Meanwhile, after receiving the current output signal of the infrared receiver, the ADC converter converts the current output signal into an infrared digital signal, the digital filter filters the infrared pulse signal with the preset frequency and the high-frequency noise with the interference frequency to output an infrared light signal contained in ambient light, the infrared light signal is transmitted to the resistance switching module to select a pull-up resistor, and meanwhile, the signal output end of the resistance switching module is connected with the signal output end of the infrared receiver, so that the electric signal obtained by converting the high-frequency signal is prevented from being applied to the infrared receiver to generate additional current; when the resistance switching module detects that the signal amplitude value output by the digital filter meets a built-in light intensity threshold value, the resistance switching module automatically switches a resistor matched with the light intensity threshold value to be connected between the infrared receiver and the digital filter, and the automatic switching process is completed by self-adaptive adjustment according to the light intensity threshold value provided in the configurable reference power supply; under the action of a pull-up resistor newly gated by the resistance switching module, the sensitivity of the infrared receiver to receiving infrared signals is adjusted, and the ADC updates the infrared detection signals at the signal output end of the ADC according to the demodulation signals currently output by the infrared receiver. Compared with the prior art, the infrared receiving system adopts a pure hardware means to automatically switch the resistance of the matching resistance in real time, so that the sensitivity of the infrared receiver is adjusted to adapt to ground detection, wall detection or distance measurement under various environmental light intensity scenes and inhibit the interference of environmental light with different intensities. The method is a process of adaptively adjusting internal parameters of the system, reduces participation control of software, improves the ambient light anti-interference capability and infrared detection efficiency of the infrared receiving system, improves reusability of an infrared receiving circuit, and saves hardware cost.
Preferably, the infrared receiving system further includes a glitch filtering module, as shown in a dashed box of fig. 2, a signal output end of the glitch filtering module is connected to a signal input end of the ADC converter, and a signal input end of the glitch filtering module is connected to a signal output end of the infrared receiver, and is used for filtering a glitch signal output by the infrared receiver; the burr filtering module is a first-order resistance-capacitance filter comprising a resistor R and a capacitor C, the first-order resistance-capacitance filter is a simple first-order resistance-capacitance filtering network formed by a resistor R and a capacitor C, one end of the resistor R is connected to a connection point between the output end of the infrared receiver and the output end of the resistance switching module, the other end of the resistor R is connected with one end of the capacitor C, the other end of the capacitor C is grounded, the signal input end of the ADC is connected with the connection point of the resistor R and the capacitor C, and the connection point of the resistor R and the capacitor C is used as the signal output end of the burr filtering module. The first-order resistance-capacitance filter can filter interference of high-frequency noise by setting higher cut-off frequency, and provides low-noise signals to be converted for the ADC. As shown in fig. 2, in the infrared receiving system, the burr filtering module, the ADC converter, the digital filter and the resistance switching module are connected to form a closed feedback loop, so as to further improve the efficiency and precision of infrared detection under various light intensity environments. The connection relationship and the internal structure of the other modules except the burr filtering module are disclosed in the foregoing embodiments, and will not be described again.
Referring to fig. 3, another embodiment of the present invention provides an SOC chip, where a port of the SOC chip is connected to a signal output end of an external infrared receiver, the infrared receiver is configured to receive an infrared light signal and an infrared pulse signal of an external environment, and meanwhile, the infrared receiver further receives high-frequency noise containing interference frequencies from the external environment, and in this embodiment, the ambient light includes types of ambient light signals such as sunlight, solar light pipe light, and bathroom light, where the infrared light signal component is more; the infrared transmitting tube in the external environment modulates and transmits infrared pulse signals to the ground, the wall surface or the obstacle, and then the infrared pulse signals are received by the infrared receiver after being reflected by the ground, the wall surface or the obstacle, wherein the infrared pulse signals are modulated signals with preset frequency, and the infrared pulse signals are signals of an infrared transmission medium with the wavelength of 940 nm. Therefore, the SOC chip can be used for detecting and processing the infrared pulse signals with preset frequency, high-frequency noise with interference frequency and ambient light signals output by the infrared receiver. The SOC chip and its external infrared receiver may form part of the same type of infrared receiving system described above.
As shown in fig. 3, the SOC chip includes an ADC converter, a digital filter, and a resistance-switching module. The signal input end of the ADC converter is connected with the signal output end of the infrared receiver and is used for receiving the output signal of the infrared receiver and converting the output signal into a digital signal, and meanwhile, the signal output end of the ADC converter is used for outputting an infrared detection signal of the infrared receiving system, and the infrared detection signal can be a digital signal which is output after being processed by the resistance switching module and the digital filter or a digital signal which is output by the infrared receiver and is obtained after analog-digital conversion. The sampling input end of the digital filter is connected with the signal output end of the ADC converter, and is used for filtering the infrared pulse signal with the preset frequency and the high-frequency noise with the interference frequency so as to output an ambient light signal, and it should be noted that the ambient light signal mentioned in this embodiment is a low-frequency infrared light signal. The control input end of the resistance switching module is connected with the signal output end of the digital filter, and the amplitude value of the filtered signal output by the digital filter is used for being transmitted to the resistance switching module to serve as a basis for switching resistance parameters, so that a pull-up resistor is selected in a targeted mode according to the amplitude of an ambient light signal and fed back to the pull-up resistor in the resistance switching module to adjust the sensitivity of the infrared receiver to infrared light. The control input end of the resistance switching module is connected with the signal output end of the digital filter, and the amplitude value of the filtered signal output by the digital filter is used for being transmitted to the resistance switching module to be used as the basis for switching the resistance parameters. The amplitude of the infrared light signal output by the digital filter changes along with the change of the ambient light intensity, so that the amplitude value of the signal transmitted to the resistance switching module changes in real time, and in order to avoid misjudgment, the resistance switching module needs to perform pull-up resistance switching of different resistance parameters so as to adapt to the current light intensity of the ambient light. The signal output end of the resistance switching module is connected with the signal output end of the infrared receiver, the control input end of the resistance switching module is connected with the signal output end of the digital filter, and the electric signal obtained by converting the high-frequency noise containing the interference frequency can be prevented from being applied to the infrared receiver to generate additional current and fed back to a pull-up resistor in the resistance switching module so as to influence the sensitivity of the infrared receiver to infrared light. And the resistance switching module is internally provided with a plurality of pull-up resistors with different resistance values, and a plurality of light intensity thresholds are correspondingly arranged and are respectively matched with the signal amplitude values output by the digital filter under the corresponding light intensity scene. Compared with the embodiment in which the resistance switching module is not integrated in the SOC chip, the embodiment does not need to use multiple ports of the main control chip to control multiple external pull-up branches, so that the integration level of the infrared receiving system is improved, chip pin resources are saved, and the multiplexing degree of the chip system is further improved. The ambient light signal here may be equivalent to ambient light that can interfere with the infrared detection circuitry of the prior art, and is primarily an infrared light signal.
Based on the difference of the light signal intensity received by the infrared receiver, the amplitude value of the signal transmitted to the resistance switching module also changes, so that the resistance switching module is controlled to change the internal pull-up resistor. And when the signal amplitude value output by the digital filter reaches a light intensity threshold value, the pull-up resistor matched with the resistance value is selected to be conducted into the circuit, so that the resistance switching module selects the pull-up resistor matched with the corresponding light intensity threshold value to be connected between the infrared receiver and the digital filter according to the matching condition of the signal amplitude value output by the digital filter and the built-in light intensity threshold value, the burr filtering module, the ADC converter, the digital filter and the resistance switching module are connected to form a closed loop structure, the sensitivity of the light intensity received by the infrared receiver is changed according to the resistance value of the connected pull-up resistor, the infrared detection signal output by the ADC converter is regulated to be free from the interference of ambient light of various light intensities, the occurrence of the infrared detection erroneous judgment condition is reduced, the infrared receiving system plays a normal infrared detection function, and the erroneous judgment is not easy to occur. And the ambient light anti-interference capability of the infrared receiving system is improved. Wherein, the resistance value of the selectable pull-up resistor in the resistance switching module is matched with different light intensities; the connection structure between the pull-up resistor inside the resistance switching module and the infrared receiver plays a role in pulling up the output signal of the infrared receiver.
When the resistance switching module detects that the signal amplitude value output by the digital filter meets a built-in light intensity threshold value, the resistance switching module automatically switches a pull-up resistor matched with the light intensity threshold value to be connected between the infrared receiver and the digital filter, and the automatic switching process is completed by self-adaptive adjustment according to the light intensity threshold value provided in the configurable reference power supply; specifically, as shown in fig. 3, the resistance switching module includes a configurable selector, and a preset number of pull-up resistors, such as R1, R2 … Rn; the configurable selector is provided with a preset number of signal input ends which are respectively connected with one ends of pull-up resistors with matched resistance values, the other ends of the pull-up resistors are connected with a power supply VCC, the function of adjusting the output voltage of the infrared receiver by pulling up is achieved, and the voltage can be pulled up to 3.3V in the embodiment; the selection output end of the configurable selector is connected with the signal output end of the infrared receiver, and the configurable selector controls the infrared receiver to adapt to light intensity change by switching and selecting proper pull-up resistors, namely, the receiving sensitivity of the infrared receiver is regulated under the action of the pull-up resistors in the resistance switching module, and interference caused by ambient light is restrained. The selection end of the configurable selector is used as the control input end of the resistance switching module, the control input end of the resistance switching module is connected with the signal output end of the digital filter, so that the configurable selector is controlled by the signal amplitude value of the signal output end of the digital filter, is configured to automatically switch the matched pull-up resistor into a closed loop formed by the ADC converter, the digital filter and the resistance switching module according to the light intensity threshold value reached by the signal amplitude value output by the digital filter, and the infrared detection result output by the ADC converter is identifiable by automatically configuring the pull-up resistor, and can exert a normal infrared detection mechanism under the current environment light intensity condition, including ground detection, wall detection, infrared ranging, obstacle avoidance and the like.
Under this embodiment, the configurable selector is also configured with a light intensity threshold. The pull-up resistor R1 corresponds to the light intensity threshold E1, the pull-up resistor R2 corresponds to the light intensity threshold E2, the pull-up resistor Rn corresponds to the light intensity threshold En, if R1 is larger than R2 and R2 is larger than Rn, E1 is smaller than E2 and E2 is smaller than En, for example, when the light intensity of an infrared signal is changed from E1 to E2, the resistance switching module controls the original pull-up resistor R1 to be selectively switched to the pull-up resistor R2 according to the signal amplitude value input by the selection end of the configurable selector, so that the pull-up effect of the output end of the infrared receiver is changed, and the infrared receiver can be changed from a saturated state to an unsaturated state so as to adapt to the interference brought by the current strong light environment. Therefore, the electric signal converted by the infrared receiver is effectively regulated, and the sensitivity of the infrared receiver to infrared light signals is regulated so as to realize the adaptation of the infrared receiver to light intensity changes; the light intensity threshold is a signal amplitude value which is preconfigured according to the light intensity received by the infrared receiver, so that the sensitivity of the infrared receiver for receiving infrared modulation signals in various types of ambient light scenes is adjusted, the ambient light interference of different intensities is restrained, and the ambient light anti-interference capability of the infrared receiver is improved.
The embodiment of the invention uses the SOC chip to improve the integration level of the infrared receiving circuits of the same type, and reduces the pin resources of the chip and saves the hardware cost by integrating the capacitance resistor and the resistance switching module in the chip. The SOC chip automatically switches the resistance of the matching resistance value in real time on the premise of not needing software intervention, so that the sensitivity of the infrared receiver is adjusted to adapt to ground detection, wall detection or distance measurement under the scenes of various types of environment light reflecting surfaces, and environmental light interference with different intensities is restrained. The method is a process for adaptively adjusting the internal parameters of the chip, reduces the participation control of software, and improves the efficiency and the precision of infrared detection.
Preferably, as shown in fig. 4, the burr filtering module (as shown in a dotted line box part of fig. 4) is connected between the ADC converter and the infrared receiver, a signal input end of the burr filtering module is connected to a signal output end of the infrared receiver, and is used for receiving an output signal of the infrared receiver and filtering the burr signal contained in the output signal, where the burr filtering module is a first-order resistance-capacitance filter including a resistor R and a capacitor C, the first-order resistance-capacitance filter is a simple first-order resistance-capacitance filter network composed of a resistor R and a capacitor C, one end of the resistor R is connected to a connection point between the output end of the infrared receiver and the output end of the resistance switching module, the other end of the resistor R is connected to one end of the capacitor C, the other end of the capacitor C is grounded, and the signal input end of the ADC converter is connected to a connection point between the resistor R and the capacitor C, and the connection point between the resistor R and the capacitor C is used as the signal output end of the burr filtering module. The first-order resistance-capacitance filter can filter the interference of high-frequency noise by setting a higher cut-off frequency, and provides a low-noise signal to be converted for the ADC. The cut-off frequency of the burr filtering module can be set in a high frequency band, so that the ADC converter is allowed to convert more frequency signals, and further infrared detection accuracy of the SOC chip is improved.
Preferably, the ADC converter adopts a Successive Approximation Register (SAR) analog-to-digital converter, which occupies a smaller chip area, has a higher conversion rate, and has a lower hardware cost than other ADC converters of other types.
Preferably, the digital filter may be implemented with a first-order IIR, a second-order IIR, an FIR or other type of digital low-pass filter, which is designed as an IIR low-pass filter or an FIR low-pass filter based on the frequency characteristics of the ambient light. The Infinite Impulse Response (IIR) filter is simple in structure, high in selectivity can be obtained by using a lower order number, used memory cells are few, calculated amount is small, and efficiency is high. Thereby improving the reliability of the filtering. The digital filter is disposed between the resistance switching module and the ADC converter, and is configured to filter the infrared pulse signal with the preset frequency and the high-frequency noise with the interference frequency, so as to output an ambient light signal, where it should be noted that the ambient light signal in this embodiment is a low-frequency infrared light signal. The signal output end of the digital filter is connected with the control input end of the resistance switching module, and the amplitude value of the filtered signal output by the digital filter is used as the basis for the resistance switching module to execute the switching resistance parameter. The digital filter can screen out the ambient light signal as the basis of resistance switching, and simultaneously based on the closed loop, the electric signal converted by the noise signal with higher frequency can be prevented from being applied to the infrared receiver to generate additional current, so that the voltage at two ends of the pull-up resistor in the resistance switching module is not in a normal state, and the sensitivity of the infrared receiver is influenced.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention and not for limiting the same; while the invention has been described in detail with reference to the preferred embodiments, those skilled in the art will appreciate that: modifications may be made to the specific embodiments of the present invention or equivalents may be substituted for part of the technical features thereof; without departing from the spirit of the invention, it is intended to cover the scope of the invention as claimed.
Claims (8)
1. The infrared receiving system for inhibiting the interference of the ambient light comprises an infrared receiver and is used for receiving infrared light signals of the external environment, and is characterized by further comprising an ADC (analog-to-digital converter), a digital filter and a resistance switching module;
the signal input end of the ADC converter is connected with the signal output end of the infrared receiver and is used for receiving the output signal of the infrared receiver and converting the output signal into a digital signal, and meanwhile, the signal output end of the ADC converter is used for outputting an infrared detection signal of the infrared receiving system;
the sampling input end of the digital filter is connected with the signal output end of the ADC converter and is used for filtering the signal converted and output by the ADC converter;
the control input end of the resistance switching module is connected with the signal output end of the digital filter and is used for gating the corresponding pull-up resistor to be connected between the signal output end of the infrared receiver and the power supply according to the amplitude value of the filtered signal output by the digital filter;
the resistance switching module comprises a configurable selector and a preset number of pull-up resistors;
the configurable selector is provided with a preset number of signal input ends which are respectively connected with one end of the pull-up resistor with matched resistance values, the other end of the pull-up resistor is connected with the power supply, the selection output end of the configurable selector is connected with the signal output end of the infrared receiver, the selection end of the configurable selector is used as the control input end of the resistance switching module and is used for automatically switching the matched pull-up resistor to adjust the output signal of the infrared receiver according to the light intensity threshold value reached by the signal amplitude value output by the digital filter;
the light intensity threshold value is a signal amplitude value which is preconfigured according to the light intensity received by the infrared receiver;
the resistance switching module is internally provided with a plurality of pull-up resistors with different resistance values, and a plurality of preset light intensity thresholds are correspondingly matched with the signal amplitude values output by the digital filter under the corresponding light intensity scene respectively;
the resistance switching module selects a pull-up resistor matched with a corresponding light intensity threshold to be connected between the infrared receiver and a power supply according to the matching condition of the signal amplitude value output by the digital filter and the built-in light intensity threshold, so that the sensitivity of the infrared receiver for receiving infrared light is changed according to the resistance value of the connected pull-up resistor, and the sensitivity of the infrared receiver is adjusted by the resistance switching module through automatically switching the pull-up resistor matched with the resistance value, so that the output signal of the infrared receiver is adaptively adjusted;
the resistance value of the selectable pull-up resistor in the resistance switching module is matched with different light intensities, and when the ambient light intensity received by the infrared receiver is larger, the pull-up resistor gated in the resistance switching module is smaller; when the intensity of the ambient light received by the infrared receiver is smaller, the pull-up resistance of the internal gating of the resistance switching module is larger.
2. The infrared receiving system according to claim 1, further comprising a glitch filtering module, wherein a signal output end of the glitch filtering module is connected to a signal input end of the ADC converter, and a signal input end of the glitch filtering module is connected to a signal output end of the infrared receiver, and is configured to filter a glitch signal output by the infrared receiver; the burr filtering module is a first-order resistance-capacitance filter comprising a resistor and a capacitor.
3. The infrared receiving system according to claim 1, wherein the ADC converter is a Successive Approximation Register (SAR) analog-to-digital converter.
4. The infrared receiving system according to claim 1, wherein the digital filter is a low pass filter.
5. An SOC chip, one port of which is connected with the signal output end of an external infrared receiver, is characterized in that the SOC chip integrates an ADC converter, a digital filter and a resistance switching module;
the signal input end of the ADC converter is connected with the signal output end of the infrared receiver and is used for receiving the output signal of the infrared receiver and converting the output signal into a digital signal, and meanwhile, the signal output end of the ADC converter is used for outputting an infrared detection signal of the infrared receiving system;
the sampling input end of the digital filter is connected with the signal output end of the ADC converter and is used for filtering the signal converted and output by the ADC converter;
the control input end of the resistance switching module is connected with the signal output end of the digital filter and is used for gating the corresponding pull-up resistor to be connected between the signal output end of the infrared receiver and the power supply according to the amplitude value of the filtered signal output by the digital filter;
the resistance switching module comprises a configurable selector and a preset number of pull-up resistors;
the configurable selector is provided with a preset number of signal input ends which are respectively connected with one end of the pull-up resistor with matched resistance values, the other end of the pull-up resistor is connected with a power supply, the selection output end of the configurable selector is connected with the signal output end of the infrared receiver, the selection end of the configurable selector is used as the control input end of the resistance switching module and is used for automatically switching the matched pull-up resistor to adjust the output signal of the infrared receiver according to the light intensity threshold value reached by the signal amplitude value output by the digital filter;
when the resistance switching module detects that the signal amplitude value output by the digital filter meets a built-in light intensity threshold value, the resistance switching module automatically switches a pull-up resistor matched with the light intensity threshold value to be connected between the infrared receiver and the digital filter;
the light intensity threshold value is a signal amplitude value which is preconfigured according to the light intensity received by the infrared receiver; the power supply is a power supply configured in the SOC chip or a power supply connected to a power supply end of the SOC chip;
the resistance switching module is internally provided with a plurality of pull-up resistors with different resistance values, and a plurality of preset light intensity thresholds are correspondingly matched with the signal amplitude values output by the digital filter under the corresponding light intensity scene respectively; wherein, the pull-up resistor R1 corresponds to the light intensity threshold E1, the pull-up resistor R2 corresponds to the light intensity threshold E2, the pull-up resistor Rn corresponds to the light intensity threshold En, if R1 is greater than R2 and R2 is greater than Rn, E1 is less than E2 and E2 is less than En.
6. The SOC chip of claim 5, further comprising a glitch filter module, wherein a signal output of the glitch filter module is connected to a signal input of the ADC converter, and a signal input of the glitch filter module is connected to a signal output of the infrared receiver, for filtering out glitch signals output by the infrared receiver; the burr filtering module is a first-order resistance-capacitance filter comprising a resistor and a capacitor.
7. The SOC chip of claim 5, wherein the ADC converter is a Successive Approximation Register (SAR) analog-to-digital converter.
8. The SOC chip of claim 5, wherein the digital filter is a low pass filter.
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| CN114577240A (en) * | 2021-12-20 | 2022-06-03 | 深圳市志奋领科技有限公司 | Method, system and sensor for dynamically adjusting photoelectric detection parameters |
| CN117249898B (en) * | 2023-08-31 | 2024-04-09 | 北京融合未来技术有限公司 | Pixel circuit of detector, detector and equipment |
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