Microampere current detection system

Abstract

A microampere current detection system includes a solar panel, a battery pack, a voltage stabilizing circuit, an instrumentation amplifier, a sampling resistor, a microcontroller unit (MCU), and an XBee ® communication module. Two ends of the sampling resistor are connected to a sensor and convert current to voltage. The instrumentation amplifier outputs an amplified voltage signal. The MCU continuously acquires the voltage signal by using a hardware direct memory access (DMA) function of the MCU and obtains an analogue to digital converter (ADC) sampling value through digital filtering. The MCU calculates a current parameter value based on the ADC sampling value, compresses and encrypts the ADC sampling value and current parameter data. The MCU also sends a generated package to the communication module, and send the package data wirelessly via the communication module. Protocols such as 802.15.4 may be used.

Description

Current loop Current output- FIG. 2 Upper computer XBee coordinator XBee 602.15.4 ^|w*M*WZZWWWWZZZZZZ^^ FIG. 3 2 / 6 Access into a to-be-detected sensor Obtaining of a current j signal Current and voltage | conversion Current parameter data J filter calculation | Power-on start of a | wireless server ______________________................................... | Power-on start of an XBee communication [ module _______________ | A terminal is accessed into the wireless server _ J Wireless transmission of | data i____________ Data is received by an | upper computer f................................................... ____________________________________ | Data is displayed by the upper computer 1 End FIG. 4 O Radio Modlues CI -0013A20041F1B88C Named Function :ZIGBEE TH Reg Port:COM5-9600 / 8 / N / l / N-AT MAC:0OBA2OO4IFIB88C • • o A.ZZl £._- J DTR RTS BRK Close Record Detach Console log ADC2.624853, Cwent:535.97070 ADC:2.624853, Cunwt:535J7070 41 44 43 3A 20 32 2E 36 32 34 38 35 33 20 20 43 75 72 72 65 6E 74 3A20 35 33 35 2E 39 37 30 37 38 33 0D 41 44 43 3A 20 32 2E 36 32 34 38 35 33 2C 20 43 75 72 72 65 6E 74 3A20 35 33 35 2E 39 37 30 37 38 33 0D Send packets Send a single packet Name Data O Q'Send selected packet 0 Send sequence 0 Transmit interval: 500 Repeat times j Loop infinitely ...... FIG. 5 6 / 6 — General analysis ........... J Cl:4.00mA / div C l-Maxi 8.6680mA Cl-Awg 6.0140mA Cl-Min 4.2300mA 3.800V ow 3.0 V 0.004A] 0A OVP OCP o.ooov. ?v 0.000A0.3A OVP OCP 0.000V. „ T 4.5 V 0.000AQ.1A OVP OCP FIG. 7 MICROAMPERE CURRENT DETECTION SYSTEM TECHNICAL FIELD

[0001] The present disclosure relates to the field of current detection technologies, and in particular, relates to a microampere current detection system. BACKGROUND

[0002] With gradual development of new energy, solar panels are used in more and more fields. In a power supply environment of the solar panel, currents on some high-end sensors will vary with illumination intensity, and therefore, it is crucial to detecting current changes of the sensors. In this case, a high-precision current detection system is needed, which can meet a power supply need under the power supply environment of the solar panel. However, the existing high-precision current detection system cannot meet requirements in terms of size and power consumption. SUMMARY

[0003] An objective of the present disclosure is to provide a microampere current detection system which is featured in high precision, ultralow power consumption and small size, and supports wireless communication.

[0004] To achieve the above objective, the present disclosure provides the following technical solutions.

[0005] The present disclosure provides a microampere current detection system, including: a solar panel, a battery pack, a voltage stabilizing circuit, an instrumentation amplifier, a sampling resistor, a microcontroller unit (MCU), and an XBee communication module, where the voltage stabilizing circuit is separately connected to the solar panel, the battery pack, the instrumentation amplifier, the MCU, and the XBee communication module; and a high voltage end and a low voltage end of the instrumentation amplifier are connected to two ends of the sampling resistor; and

[0006] the two ends of the sampling resistor are connected to a to-be-detected sensor, and are configured to convert a to-be-detected current on the to-be-detected sensor into a to-be-detected voltage; the instrumentation amplifier is configured to: amplify the to-be-detected voltage and output an amplified voltage signal; the MCU is configured to: continuously acquire the voltage signal by using a hardware data memory access (DMA) function of the MCU, and obtain an analog to digital converter (ADC) sampling value through digital filtering; the MCU is further configured to: calculate a corresponding current parameter value based on the ADC sampling value, compress and encrypt the ADC sampling value and corresponding current parameter data, send a generated package to the XBee communication module, and send package data in a wireless manner via the XBee communication module.

[0007] Optionally, the voltage stabilizing circuit includes a TLV70233 linear voltage stabilizing chip and two filtering and voltage-stabilizing chip capacitors, and a positive voltage output by the voltage stabilizing chip is configured to supply power to the instrumentation amplifier, the MCU, and the XBee communication module.

[0008] Optionally, the positive voltage output by the voltage stabilizing chip is converted into a negative voltage via an MAXI697 charge pump chip to supply power to the instrumentation amplifier.

[0009] Optionally, the instrumentation amplifier adopts an INA126UA chip, and is configured to set a gain factor Av via one precision resistor.

[0010] Optionally, a maximum voltage value capable of being output by the instrumentation amplifier is Vfmax=RfxIxAv, where Rf is a resistance value of the sampling resistor, and I is a value of the to-be-detected current.

[0011] Optionally, the two ends of the sampling resistor are connected to a current output end and a current input end of the to-be-detected sensor via two wiring terminals respectively.

[0012] Optionally, a digital filtering method adopted by the MCU is a mean filtering method.

[0013] Optionally, voltage precision capable of being identified by the MCU is Res=( Vin ax■ Vmin) / (2AN), where N is a bit number of an ADC reference voltage in the MCU, Vmax is a maximum value of the ADC reference voltage, and Vmin is a minimum value of the ADC reference voltage.

[0014] Optionally, the MCU is configured to calculate a current parameter value I corresponding to an ADC sampling value Vf by using a formula I=Vf / (Rfx Av), where Rf is a resistance value of the sampling resistor, and Av is a gain factor of the instrumentation amplifier.

[0015] Optionally, the XBee communication module is in communication connection to an upper computer via an XBee coordinator; the XBee coordinator is configured to: receive the package data sent by the microampere current detection system and forward the package data to the upper computer; and the upper computer is configured to decode and decompress the package data to obtain the ADC sampling value and corresponding current parameter data for displaying.

[0016] According to specific embodiments provided in the present disclosure, the present disclosure has the following technical effects:

[0017] The microampere current detection system provided in the present disclosure includes the solar panel, the battery pack, the voltage stabilizing circuit, the instrumentation amplifier, the sampling resistor, the MCU, and the XBee communication module. The system in the present disclosure adopts the MCU with ultralow power consumption, the high-gain instrumentation amplifier and the high-precision sampling resistor, has resolution precision of 1 uA, and is featured in high precision and high stability. According to the present disclosure, a wireless communication function is achieved via the XBee communication module. In addition, through multi-module cellular network connection, a plurality of systems may further simultaneously acquire current data and gather the current data into the corresponding upper computer. The system in the present disclosure has an extra small size of 2*2 cm, and ultralow power consumption with average power consumption of 22 mW. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] To describe the technical solutions in embodiments of the present disclosure or in the prior art more clearly, the accompanying drawings required for the embodiments are briefly described below. Apparently, the accompanying drawings in the following description show merely some embodiments of the present disclosure, and those of ordinary skill in the art may still derive other accompanying drawings from these accompanying drawings without creative efforts.

[0019] FIG. 1 is a schematic diagram of a structure and a principle of a microampere current detection system according to the present disclosure;

[0020] FIG. 2 is a schematic diagram of connection between a microampere current detection system and a to-be-detected sensor according to the present disclosure;

[0021] FIG. 3 is a schematic diagram of communication connection between a microampere current detection system and an upper computer according to the present disclosure;

[0022] FIG. 4 is a schematic diagram of overall workflow of a software part of a microampere current detection system according to the present disclosure;

[0023] FIG. 5 is a schematic diagram of an interface of an upper computer;

[0024] FIG. 6 is a schematic diagram of size of a hardware part of a microampere current detection system according to the present disclosure; and

[0025] FIG. 7 is a schematic diagram of overall power consumption monitoring of a microampere current detection system according to the present disclosure. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0026] The technical solutions of the embodiments of the present disclosure are clearly and completely described below with reference to the drawings in the embodiments of the present disclosure. Apparently, the described embodiments are merely a part rather than all of the embodiments of the present disclosure. All other examples obtained by a person of ordinary skill in the art based on the examples of the present disclosure without creative efforts shall fall within the protection scope of the present disclosure.

[0027] An objective of the present disclosure is to provide a microampere current detection system which is featured in high precision, ultralow power consumption and small size, and supports wireless communication.

[0028] In order to make the above objective, features and advantages of the present disclosure clearer and more comprehensible, the present disclosure will be further described in detail below in combination with accompanying drawings and particular implementation modes.

[0029] Refer to FIG. 1. The present disclosure provides a microampere current detection system, including a solar panel, a battery pack, a voltage stabilizing circuit, an instrumentation amplifier, a sampling resistor, a microcontroller unit (MCU), and an XBee communication module. The voltage stabilizing circuit is separately connected to the solar panel, the battery pack, the instrumentation amplifier, the MCU, and the XBee communication module. A high voltage end and a low voltage end of the instrumentation amplifier are connected to two ends of the sampling resistor. The two ends of the sampling resistor are connected to a to-be-detected sensor, and are configured to convert a to-be-detected current on the to-be-detected sensor into a to-be-detected voltage. The instrumentation amplifier is configured to: amplify the to-be-detected voltage and output an amplified voltage signal. The MCU is configured to: continuously acquire the voltage signal by using a hardware data memory access (DMA) function of the MCU, and obtain an analog to digital converter (ADC) sampling value through digital filtering. The MCU is further configured to: calculate a corresponding current parameter value based on the ADC sampling value, compress and encrypt the ADC sampling value and corresponding current parameter data, send a generated package to the XBee communication module, and send package data in a wireless manner via the XBee communication module.

[0030] Refer to FIG. 1. A solar power supply part of the system in the present disclosure is implemented by a small solar panel that is configured to output a 3.7V voltage in a normal sunshine environment.

[0031] The power supply part of the system in the present disclosure adopts a small polymer pouch battery, which is referred to as a battery pack for short, and has a 3.7V nominal voltage value. In the daytime, the solar panel is configured to: receive solar energy and convert the solar energy into electric energy to supply power to the system, and charge the battery pack with the remaining power. At night, the battery pack is configured to supply power to the system.

[0032] The battery pack is configured to provide a direct-current power supply for a voltage stabilizing part of the system, and the voltage stabilizing circuit is configured to stabilize a voltage output by the power supply part at 3.3 V Specifically, the voltage stabilizing circuit includes a TLV70233 linear voltage stabilizing chip, and further includes two filtering and voltage-stabilizing chip capacitors. A maximum output current of the voltage stabilizing chip may reach 300 mA, which is enough for the use of the whole system. A positive voltage output by the voltage stabilizing chip is configured to supply power to the subsequent instrumentation amplifier, MCU, and XBee communication module. Further, the voltage stabilizing part of the system is further configured to provide a negative voltage. The positive voltage output by the voltage stabilizing chip passes through an MAXI697 charge pump chip, so that a 3.3V positive voltage is converted into a 3.3 V negative voltage. A drive capability of the chip is 20 mA, which is enough to meet a power demand of the subsequent instrumentation amplifier.

[0033] The instrumentation amplifier adopts an INA126UA chip. The chip has a very high gain, which can reach a 10000-time differential-mode amplification gain. The chip is configured to set a gain factor by one precision resistor.

[0034] A high voltage end and a low voltage end of the instrumentation amplifier are connected to two ends of the sampling resistor, where a resistance value of the sampling resistor is 5 ohms, and has precision of 0.1%. The two ends of the sampling resistor are respectively connected to an input end and an output end for sampling. The input end and the output end are linked with two wiring terminals for facilitate connection of the to-be-detected sensor.

[0035] Connection between the system and the to-be-detected sensor according to the present disclosure is as shown in FIG. 2. A to-be-detected device in FIG. 2 is a sensor device which needs to be detected, and includes a temperature-sensitive resistance sensor (a resistance value is changed according to a temperature change for making a value of a flow-through current change), a light-sensitive resistance temperature (a resistance value is changed according to a light intensity change for making a value of a flow-through current change), a pressure-sensitive resistance sensor (a resistance value is changed according to a pressure change for making a value of a flow-through current change), and the like. The to-be-detected device needs to output a to-be-detected current. A current output end is connected to a current input end + of the system in the present disclosure, and the current output end - needs to be accessed into a current loop, to form a complete loop with GND. A hardware part in the present disclosure needs to connect to a small solar panel with an output voltage of 3.7 V, and is connected into a corresponding battery pack. The battery pack is configured to perform power charging management on the hardware part. The solar panel and the battery pack are configured to supply power to the system in the present disclosure.

[0036] The MCU part adopts an STM32L011F4 master control chip. The chip is featured in ultralow power consumption and small size, and plays a very important role in a low-power-consumption design. The MCU is configured to: acquire an analogue voltage signal output by the instrumentation amplifier, perform digital optimization (including algorithm optimization and data optimization) on the signal, and send a processed digital signal to the subsequent XBee communication module for remote communication.

[0037] The XBee communication module is an XBee chip. The chip is an updated version of a ZigBee chip, and has advantages of low power consumption, stable transmission, data encryption, an adjustable transmission distance, a small size, and the like in addition to all features (a capability of implementing a cellular network) of the ZigBee.

[0038] FIG. 3 is a schematic diagram of communication connection between a hardware part of a system and an upper computer according to the present disclosure. The right half part in FIG. 3 indicates an overall hardware part of the present disclosure, and each hardware part includes a sampling resistor, an instrumentation amplifier, an MCU (integrated with high-precision ADC), and an XBee communication module. In addition, each hardware part needs to carry a corresponding solar panel and small battery pack. In the present disclosure, there may be a plurality of systems to separately acquire a corresponding to-be-detected current, where each hardware part is configured to correspondingly detect a current of a sensor.

[0039] Specifically, the XBee communication module is in communication connection to the upper computer via an XBee coordinator. The XBee coordinator is configured to: receive the package data sent by the microampere current detection system and forward the package data to the upper computer. The upper computer is configured to: decode and decompress the package data to obtain an ADC sampling value and corresponding current parameter data for displaying.

[0040] The XBee communication module in the present disclosure is an updated version of the ZigBee module, and can establish a same cellular network function with lower power consumption. The system in the present disclosure is used as a terminal for forming a cellular network with one XBee coordinator and a plurality of wireless servers, to implement simultaneous access of a plurality of terminals. An adopted network communication protocol is XBee 802.15.4. The network communication protocol supports channel encryption. After a port number is set, a non-relevant device cannot be accessed into the network, so that data security can be improved. It can be seen that the present disclosure further can implement simultaneous detection of a plurality of to-be-detected sensors by a plurality of terminals in a case that a hardware device has an extra small size and extra small power consumption.

[0041] Corresponding to FIG. 3, a software part of the system in the present disclosure is divided into embedded software and upper computer software. FIG. 4 is a schematic diagram of overall workflow of a software part.

[0042] (1) Embedded software part

[0043] The hardware part of the system is accessed into the to-be-detected sensor, so that the hardware part starts to work. A current signal of the to-be-detected sensor is acquired by the sampling resistor at a front end of the instrumentation amplifier, and an amplified voltage signal is output by the instrumentation amplifier. The MCU is configured to: enable an ADC (analogue-to-digital conversion) function, and continuously acquire a voltage signal by using a hardware DMA function of the MCU. Inference caused by hardware noises and other noises can be effectively eliminated through digital filtering (mean filtering). Specifically, a filter method of sampling for a plurality of times to obtain a mean value is adopted. Data of 20 voltage signals are averaged to obtain an accurate ADC sampling value, so that inference caused by data fluctuation can eliminated.

[0044] An MCU state machine is configured to perform data processing on the voltage signal acquired by the ADC, and voltage precision Res capable of being identified by the MCU according to formula (1) is:

[0045] Res=(Vmax-Vmin) / (2AN)......(1), where

[0046] Res indicates a smallest voltage variation capable of being identified by the ADC, and is also referred to as a resolution or sampling precision. Vmax indicates a maximum value of the ADC reference voltage. Vmin indicates a minimum value of the ADC reference voltage. N is a bit number of ADC. The ADC in the MCU selected in the present disclosure has 12-Bit precision, that is, N is equal to 12. The resolution Res is equal to dividing a difference between the maximum value of the ADC reference voltage and the minimum value of the ADC reference voltage by Nth power of 2. The obtained Res value is voltage precision capable of being identified by the system in the present disclosure. A smaller number indicates higher precision. In some embodiments, Vmax is 3.3 V, Vmin is 0, and N is 12, so that the precision Res can be calculated as 0.000806 V, that is, the precision capable of being identified by the ADC is a voltage value of Res=0.000806 V.

[0047] A maximum voltage value capable of being output by the instrumentation amplifier can be calculated according to the formula (2):

[0048] Vfmax=Rf I Av......(2), where

[0049] Vfmax indicates the maximum voltage value capable of being output by the instrumentation amplifier. Rf is a resistance value of the sampling resistor. I is a value of the to-be-detected current. Av is a gain factor of the instrumentation amplifier. In the formula (2), the maximum voltage value Vfmax capable of being output by the instrumentation amplifier is equal to multiplying the resistance value of the sampling resistor with the value of the to-be-detected current, and the gain factor of the instrumentation amplifier in the system. Current parameter measuring precision of the system in the present disclosure can be obtained according to formula (2). For example, in terms of parameter setting in the present disclosure, Rf is 5 Q, Vfmax is 3.3 V, and Av is 1000. An expected current resolution measured in the present disclosure is 1 uA. According to the calculation in the formula (2), when the output to-be-detected current is 1 uA, Vfmax is 0.005>Res(0.000806). It can be concluded that the current measuring precision in the present disclosure meets a design requirement. It can be obtained, through further calculation, that a current measurement range in the present disclosure is from 0 uAto 660 uA.

[0050] Algorithms corresponding to the formula (1) and the formula (2) are written into the MCU state machine for corresponding calculation, so that a current value obtained after data filtering and calculation can be obtained. The current value is sent to the XBee wireless communication module via an UART serial communication interface for wireless sending of data. In the hardware embedded algorithm in the present disclosure, DMA is adopted for ADC data acquisition, data calibration is performed through digital filtering, and low-power-consumption application is implemented by using a method of periodically waking up a communication module.

[0051] A calculation formula for the existing current parameter value I is:

[0052] I=Vf(RfxAv)......(3), where

[0053] Vf is an existing ADC sampling value acquired by the MCU, and a corresponding current parameter value is I; Rf is a resistance value of the sampling resistor, and Av is a gain factor of the instrumentation amplifier. According to the formula (3), for example, when the output voltage of the instrumentation amplifier is 2 V, the existing current size 1=2 / (5* 1000)=400 uA can be calculated corresponding to Vf=2V in formula (3), where Rf and Av are known as fixed values.

[0054] A difference between the formula (2) and the formula (3) lies in that the formula (2) is used for detection precision demonstration, and the formula (3) is used for real-time current calculation. Vf is not a fixed integer, but is at a plurality of decimals after a decimal point of a floating-point number. It can be learned that, according to the formula (1) and the formula (2), a voltage value which is at four decimals after a decimal point can be detected, and a voltage value lower than 0.000806 V cannot be detected.

[0055] (2) Upper computer software part

[0056] Firstly, a wireless server is manufactured for an XBee communication module, and a wireless network is enabled after the wireless server is powered on. The XBee communication module on the hardware part is started after being powered on, a network parameter, including a port number and a password, is configured for the XBee communication module by the MCU, and a hardware terminal is accessed into a wireless server network. The XBee wireless communication module is configured to: after receiving the ADC sampling value and the corresponding current parameter data that are sent by the MCU via a UART serial port, send corresponding data through a wireless communication network which adopts a protocol XBee 802.15.4 on a 2.4G frequency band. The upper computer is configured to receive the corresponding ADC sampling value and the current parameter data via a wireless network server. Character string conversion is directly performed on the received transmission data, and the received ADC sampling value and the corresponding current parameter data size are displayed in real time on a screen of the upper computer directly in a form of each piece of data.

[0057] A data receiving end of the upper computer in the present disclosure is designed and manufactured by an XBee communication module with a model of XBee S2C of the Digi company, and includes a CH340 chip and a corresponding peripheral circuit. Received data is sent to the upper computer via USB. All hardware systems of a plurality of terminals form a wireless network 802.15.4 for communication through XBee; the XBee coordinator is configured to: receive relevant data sent by the receiving end, convert the relevant data via the CH340 chip, and send the corresponding received ADC sampling value and current parameter data to the upper computer via the USB. As shown in FIG. 5, an interface of the upper computer includes three parts, where an ID of the connected terminal device is displayed on the left part. The ADC sampling value (indicated by ADC) and the corresponding current parameter data (indicated by Current) that are received and that are acquired by the terminal are displayed on the upper half part on the right side. Specific data obtained after decoding is displayed on the left side, and original data is displayed on the right side. A data record state table is on the lower half part on the right side, and a threshold can be set. When a setting condition is met, corresponding data is recorded and saved into a local folder. A current threshold may be set according to an application scenario of the sensor. For example, a temperature-sensitive resistor / sensor is configured to change a resistance value according to a temperature change. When a temperature is too high, a smaller resistance value leads to an excessively large current. The abnormal state is recorded by setting the current threshold, so that a working condition of the sensor can be analyzed.

[0058] The design for the hardware and software parts of the system in the present disclosure involves technologies such as current signal acquiring, filtering, processing, low power consumption and wireless technology. A complete microampere current detection system can be formed for current detection in a direct-current voltage environment at a safe voltage less than 24 V, has the advantages of high precision, ultralow power consumption, and a small size, belongs to a non-shunt contact type measurement solution, and has a wireless communication function.

[0059] Compared with an existing current detection system, the system in the present disclosure has a plurality of obvious advantages.

[0060] (1) In the present disclosure, an ultralow-power consumption design is adopted, an MCU with ultralow-power consumption is adopted, and UFQFPN20 encapsulation with a size of only 3*3 mm is selected; and an excessive peripheral circuit design is not needed, and therefore, the system plays a key role in a PCB design and a low-power consumption design.

[0061] (2) In the present disclosure, the XBee communication module is adopted, and the module has advantages of a small size, low power consumption and a low-quiescent current. The wireless communication module has a quiescent working current of only 1 mA, has a size of only 13*19 mm, and has a current peak of 18 mA under a communication state; and an ultra-low power consumption design of the overall hardware system can be implemented by intermittent communication through software settings.

[0062] (3) As shown in FIG. 3, the XBee communication module adopted in the present disclosure is an updated version of the ZigBee module, and can form a same cellular network function under lower power consumption. The cellular network may include one network coordinator and a plurality of network servers, and can be configured to: implement simultaneous access of a plurality of terminals, and implement multi-device interconnection through the network protocol XBee 802.15.4. After a corresponding network port number is set, the network is linked. In the present disclosure further, simultaneous detection of a plurality of to-be-detected sensors by a plurality of terminals can be implemented in a case that the hardware device has an extra small size and extra small power consumption.

[0063] (4) As shown in FIG. 3, the network communication protocol adopted in the present disclosure is XBee 802.15.4. The network communication protocol supports channel encryption. After a port number is set, a non-relevant device cannot be accessed into the network, so that data security can be improved.

[0064] (5) As shown in FIG. 6, the hardware part in the present disclosure has a size of only 20*20 mm, and achieves an objective of a small size.

[0065] (6) As shown in FIG. 7, the overall hardware part is supplied with power at a 3.8V voltage in a normal working state, and has average power consumption of only 6.01 mA. Overall power consumption can be calculated as follows: P=UI=3.8*6.01=22.838, that is, the overall power consumption of the system is only 22.838 mW. Through a plurality of detections and calculations, the hardware device in the present disclosure has average power consumption of only 22.8532 mW, and can continuously work for more than 30 hours under a power supply condition of a small 200-mAh battery.

[0066] (7) In the present disclosure, solar energy is used for supplying power; in the daytime, the battery pack is configured to store excessive power, and at night, the battery pack is configured to supply power to the hardware device for working; and according to the conclusion in (6), a normal need of alternately working day and night can be met.

[0067] (8) The XBee communication module in the present disclosure adopts an intermittent communication mode, so that the wireless communication module is in an intermittent working state, and therefore, overall power consumption of the system can be effectively reduced. Specifically, in the intermittent communication mode, the MCU is configured to control wakeup and sleep of the XBee communication module via an enabling pin for waking up at a high level and sleeping at a low level, and therefore, an objective of intermittent communication wakeup is achieved.

[0068] Particular examples are used herein for illustration of principles and implementation modes of the present disclosure. The descriptions of the above embodiments are merely used for assisting in understanding the method of the present disclosure and its core ideas. In addition, those of ordinary skill in the art can make various modifications in terms of particular implementation modes and the scope of application in accordance with the ideas of the present disclosure. In conclusion, the content of the description shall not be construed as limitations to the present disclosure.

Claims

1. A microampere current detection system, comprising a solar panel, a battery pack, a voltage stabilizing circuit, an instrumentation amplifier, a sampling resistor, an microcontroller unit (MCU), and an XBee communication module, wherein the voltage stabilizing circuit is separately connected to the solar panel, the battery pack, the instrumentation amplifier, the MCU, and the XBee communication module; and a high voltage end and a low voltage end of the instrumentation amplifier are connected to two ends of the sampling resistor; andthe two ends of the sampling resistor are connected to a to-be-detected sensor, and are configured to convert a to-be-detected current on the to-be-detected sensor into a to-be-detected voltage; the instrumentation amplifier is configured to: amplify the to-be-detected voltage and output an amplified voltage signal; the MCU is configured to: continuously acquire the amplified voltage signal by using a hardware data memory access (DMA) function of the MCU, and obtain an analog to digital converter (ADC) sampling value through digital filtering; the MCU is further configured to: calculate a corresponding current parameter value based on the ADC sampling value, compress and encrypt the ADC sampling value and corresponding current parameter data, send a generated package to the XBee communication module, and send package data in a wireless manner via the XBee communication module.

2. The microampere current detection system according to claim 1, wherein the voltage stabilizing circuit comprises a TLV70233 linear voltage stabilizing chip and two filtering and voltage-stabilizing chip capacitors, and a positive voltage output by the voltage stabilizing chip is configured to supply power to the instrumentation amplifier, the MCU, and the XBee communication module.

3. The microampere current detection system according to claim 2, wherein the positive voltage output by the voltage stabilizing chip is converted into a negative voltage via an MAXI 697 charge pump chip to supply power to the instrumentation amplifier.

4. The microampere current detection system according to claim 1, wherein the instrumentation amplifier adopts an INA126UA chip, and is configured to set a gain factor Av via one precision resistor.

5. The microampere current detection system according to claim 4, wherein a maximum voltage value capable of being output by the instrumentation amplifier is Vfmax=RfxIxAv,wherein Rf is a resistance value of the sampling resistor, and I is a value of the to-be-detected current.

6. The microampere current detection system according to claim 1, wherein the two ends of the sampling resistor are connected to a current output end and a current input end of the to-be-detected sensor via two wiring terminals respectively.

7. The microampere current detection system according to claim 1, wherein a digital filtering method adopted by the MCU is a mean filtering method.

8. The microampere current detection system according to claim 1, wherein voltage precision capable of being identified by the MCU is Res=(Vmax^Vmin) / (2AN), N is a bit number of an ADC reference voltage in the MCU, Vmax is a maximum value of the ADC reference voltage, and Vmin is a minimum value of the ADC reference voltage.

9. The microampere current detection system according to claim 1, wherein the MCU is configured to calculate a current parameter value I corresponding to an ADC sampling value Vf by using a formula I=Vf / (Rfx Av), Rf is a resistance value of the sampling resistor, and Av is a gain factor of the instrumentation amplifier.

10. The microampere current detection system according to claim 1, wherein the XBee communication module is in communication connection to an upper computer via an XBee coordinator; the XBee coordinator is configured to: receive the package data sent by the microampere current detection system and forward the package data to the upper computer; and the upper computer is configured to decode and decompress the package data to obtain the ADC sampling value and the corresponding current parameter data for displaying.

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