A multi-channel analog input detection circuit with trigger wake-up

Abstract

The present invention discloses a multi-channel analog input detection circuit with trigger wake-up, which includes: at least one external signal input channel module, the external signal input channel modules are all electrically connected to the detection wake-up module, the detection wake-up module includes: MCU, the MCU is also electrically connected to the wake-up chip U1, the wake-up chip U1 is connected to the external power supply through the switch circuit module, the switch circuit module is electrically connected to the external signal input channel module; when the external signal input channel module has a signal input, the switch circuit module is turned on and triggers the wake-up chip U1, the wake-up chip U1 wakes up the MCU, and the MCU reads the external signal input channel module signal. The circuit solves the problem of waking up the MCU when one or more AD signal inputs are detected, entering a normal standby state, and the MCU detects input signals; when there is no input, the system is in a deep sleep state, thereby ensuring the lowest sleep power consumption of the entire system; and the I / O resources used are minimal, the circuit is simple, and the system strategy is simple.

Description

Technical Field

[0001] The present invention relates to the technical field of detection circuits, and in particular to a multi-channel analog input detection circuit with trigger wake-up. Background Art

[0002] There are two general triggering methods for microcontroller (MCU) interrupt wakeup: edge triggering and level triggering. However, this triggering can only detect the switch state, that is, the transition from one state to another, which belongs to the digital method. When a single port input is an analog quantity, it cannot be ensured that each analog quantity can trigger the wakeup of the microcontroller. If there are multiple analog input signals, it is even more impossible to trigger the wakeup of the microcontroller. At present, the mainstream circuit uses the microcontroller to periodically scan the signal input to detect whether there is input on the I / O port. This method has high sleep power consumption and is prone to losing analog input signals due to the scanning cycle problem. Summary of the invention

[0003] An embodiment of the present invention provides a multi-channel analog input detection circuit with trigger wake-up, aiming to provide a multi-channel analog input detection circuit to reduce power consumption and prevent data loss.

[0004] In order to achieve the above object, the technical solution proposed by the present invention is:

[0005] A multi-channel analog input detection circuit with trigger wake-up, comprising: at least one external signal input channel module, the external signal input channel modules are electrically connected to the detection wake-up module, the detection wake-up module comprises: an MCU, the MCU is used to detect and read the detection signal of the external signal input channel module, the MCU is also electrically connected to a wake-up chip U1, the wake-up chip U1 is controlled to be on and off with an external power supply through a switch circuit module, the switch circuit module is electrically connected to the external signal input channel module; when the external signal input channel module has a signal input, the switch circuit module is turned on and triggers the wake-up chip U1, the wake-up chip U1 wakes up the MCU, and the MCU reads the detection signal of the external signal input channel module.

[0006] Wherein, the external signal input channel module includes: a first switch, a sampling resistor electrically connected to the first switch, the other end of the sampling resistor is electrically connected to the cathode end of the first diode, the anode end of the first diode is electrically connected to a second resistor, and the other end of the second resistor is electrically connected to a power supply, wherein the node between the cathode end of the first diode and the sampling resistor is also electrically connected to the cathode of the second diode, the anode of the second diode is electrically connected to the wake-up chip U1, the node between the anode end of the first diode and the second resistor is also electrically connected to a third resistor, the other end of the third resistor is electrically connected to the cathode of the voltage limiting diode, the anode of the voltage limiting diode is grounded, and a voltage dividing resistor is also connected in parallel at both ends of the voltage limiting diode, and the node between the voltage dividing resistor and the third resistor is electrically connected to the I / O port of the MCU.

[0007] Wherein, at least one second switch is connected in series to the cathode end of the first diode, and a sampling resistor is connected in series between the second switch and the cathode end of the first diode.

[0008] The model of the wake-up chip U1 is: UJA1078ATW / 5V or UJA1075ATW / 5V.

[0009] Among them, the switching circuit module includes: a fourth resistor electrically connected to the external signal input channel module, the other end of the fourth resistor is electrically connected to the collector of the transistor, the emitter of the transistor is electrically connected to the positive electrode of the external power supply, and a fifth resistor is also connected in series between the base of the transistor and the positive electrode of the external power supply, and a sixth resistor is also electrically connected to the node between the fifth resistor and the base of the transistor, and the other end of the sixth resistor is electrically connected to the WBIAS pin of the wake-up chip U1.

[0010] The positive terminal of the second diode is further connected in series with a seventh resistor, and the other end of the seventh resistor is electrically connected to the wake-up chip U1.

[0011] A multi-channel analog input detection circuit with trigger wake-up comprises: at least one external signal input channel module, each of which is electrically connected to a detection wake-up module, and the detection wake-up module comprises: an MCU, the MCU is used to detect and read a detection signal of the external signal input channel module, the MCU is also electrically connected to an LDO module, the LDO module is electrically connected to a level holding module, the LDO module supplies power to the MCU, and the level holding module keeps the wake-up port level of the MCU high when the MCU is in a deep sleep state; when a signal is input to the external signal input channel module, the MCU wake-up port level is pulled down to wake up the MCU, and the detection signal of the external signal input channel module is read by the MCU.

[0012] Wherein, the external signal input channel module includes: a first switch, a sampling resistor electrically connected to the first switch, the other end of the sampling resistor is electrically connected to the cathode end of the first diode, the anode end of the first diode is electrically connected to a second resistor, and the other end of the second resistor is electrically connected to a power supply, wherein the node between the cathode end of the first diode and the sampling resistor is also electrically connected to the cathode of the second diode, the anode of the second diode is electrically connected to the wake-up chip U1, the node between the anode end of the first diode and the second resistor is also electrically connected to a third resistor, the other end of the third resistor is electrically connected to the cathode of the voltage limiting diode, the anode of the voltage limiting diode is grounded, and a voltage dividing resistor is also connected in parallel at both ends of the voltage limiting diode, and the node between the voltage dividing resistor and the third resistor is electrically connected to the I / O port of the MCU.

[0013] Wherein, at least one second switch is connected in series to the cathode end of the first diode, and a sampling resistor is connected in series between the second switch and the cathode end of the first diode.

[0014] Compared with the prior art, the embodiment of the present invention provides a multi-channel analog input detection circuit with trigger wake-up, which solves the problem that when there are one or more AD (analog) signal input detections, when the single-chip microcomputer enters the sleep state, this analog (or switch) input signal can wake up the single-chip microcomputer through the interrupt wake-up port of the single-chip microcomputer, enter the normal standby state, and then the single-chip microcomputer detects this analog input signal again; when there is no input, the system is in a deep sleep state, thereby ensuring the lowest sleep power consumption of the entire system (below 80uA); and the single-chip microcomputer I / O resources used are minimal, the circuit is simple, and the system strategy is simple. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying any creative work.

[0016] Figure 1 A circuit diagram of a first embodiment of a multi-channel analog input detection circuit with trigger wake-up provided in an embodiment of the present invention;

[0017] Figure 2 A circuit diagram of a second embodiment of a multi-channel analog input detection circuit with trigger wake-up provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0018] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] It should be understood that when used in this specification and the appended claims, the terms "include" and "comprises" indicate the presence of described features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0020] It should also be understood that the terms used in this specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the specification of the present invention and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0021] It should be further understood that the term "and / or" used in the present description and the appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0022] Please refer to the attached Figure 1 , Figure 1 FIG. 1 is a circuit diagram of a first embodiment of a multi-channel analog input detection circuit with trigger wake-up of the present invention. In this embodiment, the multi-channel analog input detection circuit with trigger wake-up includes: at least one external signal input channel module, such as Figure 1 The input channel 1 and input channel 2 described in the above, the external signal input channel module are both electrically connected to the detection wake-up module, and the detection wake-up module includes: MCU, the MCU is used to detect and read the detection signal of the external signal input channel module, and specifically read the detection signal through the I / O port of the MCU. The MCU is also electrically connected to the wake-up chip U1, and the wake-up chip U1 is powered by an external power supply BAT+ (or system power supply) controlled by a switch circuit module, and the switch circuit module is electrically connected to the external signal input channel module; when the external signal input channel module has a signal input, the switch circuit module is turned on and triggers the wake-up chip U1, and the wake-up chip U1 wakes up the MCU, and the MCU reads the detection signal of the external signal input channel module. When the MCU reads the external detection data, the wake-up chip U1 immediately disconnects the switch circuit module to read the external detection data.

[0023] Since input channel 1 and input channel 2 are exactly the same, taking input channel 1 as an example, the external signal input channel module includes: a first switch SW1, electrically connected to a sampling resistor R11 of the first switch SW1, the other end of the sampling resistor R11 is electrically connected to the cathode end of the first diode D11, the anode end of the first diode D11 is electrically connected to a second resistor R15, the other end of the second resistor R15 is electrically connected to the power supply 12V-SW, and the system power supply network of the power supply 12V-SW can also be electrically connected to the vehicle power supply BAT+ end, or connected to BAT+ through a switch circuit. Among them, the node between the cathode end of the first diode D11 and the sampling resistor is also electrically connected to the cathode of the second diode D1, the anode of the second diode D1 is electrically connected to the wake-up chip U1, the node between the anode end of the first diode D11 and the second resistor R15 is also electrically connected to the third resistor R14, the other end of the third resistor R14 is electrically connected to the cathode of the voltage limiting diode VD1, the anode of the voltage limiting diode VD1 is grounded, and a voltage dividing resistor R13 is also connected in parallel at both ends of the voltage limiting diode VD1, and the node between the voltage dividing resistor R13 and the third resistor R14 is electrically connected to the I / O port of the MCU.

[0024] The cathode end of the first diode D11 is further connected in series with at least one second switch, and a sampling resistor is further connected in series between the second switch and the cathode end of the first diode D11. The first switch and the second switch may be two switches connected in parallel, or may be connected in series. Figure 1 The SPDT switch shown has a sampling resistor R12 connected in series between the other switch loop and the negative terminal of the first diode D11. In other embodiments, the first switch and the second switch are both inputs of external analog switch signals, so the number of switches can be increased according to actual needs.

[0025] In this embodiment, the model of the wake-up chip U1 is: UJA1078ATW / 5V or UJA1075ATW / 5V of NXP. The wake-up chip U1 is generally called SBC (system basic chip), that is, a small single-chip microcomputer with low power consumption.

[0026] The switch circuit module includes: a fourth resistor R3 electrically connected to the external signal input channel module, the other end of the fourth resistor R3 is electrically connected to the collector of the transistor Tr2, the emitter of the transistor Tr2 is electrically connected to the positive electrode of the external power supply, and a fifth resistor R1 is also connected in series between the base of the transistor Tr2 and the positive electrode of the external power supply, and a sixth resistor R2 is also electrically connected to the node between the fifth resistor R1 and the base of the transistor Tr1, and the other end of the sixth resistor R2 is electrically connected to the WBIAS pin of the wake-up chip U1. Tr1 is a bias tube inside U1, Tr2 and R1 form a switch circuit, R2 is connected to the WBIAS (pin 28) of U1, and R2 protects Tr1 as a current limiting resistor; R1 provides bias for the base of Tr2. The fourth resistor R3 and the seventh resistor R4 cooperate to adjust the voltage of WAKE1, so that when the input analog signal is valid (for example, when SW1 is connected to R12), it is ensured that the voltage of WAKE1 can wake up the chip U1 (other circuits except LDO), and the chip U1 then wakes up the single-chip microcomputer MCU through the IO port with hardware interrupt wake-up connected to the single-chip microcomputer; after the MCU wakes up (within 1 millisecond), it starts to detect the MCU-AD1 and MCU-AD2 input analog detection ports (both connected to the AD port of the single-chip microcomputer) to collect analog voltages; and then realize the multi-channel analog detection function. Among them, the BAT pin of U1 (that is, the power supply pin of this chip) is connected to the external power supply BAT+, and the internal LDO of U1 converts this external BAT+ voltage into 5V output (as long as the BAT+ network is normal, the V1 pin of U1 outputs 5V normally), and its V1 pin output is connected to the 5V power supply pin of the MCU, thereby ensuring that the MCU can always have 5V power. When the MCU is asleep, the power consumption of its internal LDO of U1 is very small, less than 10uA. This puts the entire system in a low-power sleep state.

[0027] The positive terminal of the second diode D1 is also connected in series with a seventh resistor R4, the other end of the seventh resistor R4 is electrically connected to the wake-up chip U1, and the seventh resistor R4 is the input current resistor of U1.

[0028] In the first embodiment, the control strategy of the multi-channel analog input detection circuit with triggered wake-up is: first, all external switches SW1 and SW2 are in open circuit (high impedance state), which is the default state; the whole system is powered normally, and both MCU and U1 are in normal power supply state (default state, MCU is in sleep state, and U1 is in low power sleep state as a whole); secondly, U1 sets WBIAS to a low level, so that Tr2 is in a conducting state, and WAKE1 is in a high level at this time; at the same time, U1 outputs a low level to the MCU interrupt wake-up port; the MCU enters a deep sleep state; at this time, the system power consumption is the lowest, which can reach less than 80uA; when the external switch SW1 or SW2 (or other multi-channel When the switch of any channel in the channel is turned to any gear (for example, it is connected to R12), WAKE1 is pulled to a low level, thereby waking up the microcontroller part inside U1, and U1 then sends it to the interrupt wake-up port of the microcontroller MCU through the output IO port, thereby waking up the MCU; after the MCU wakes up (generally within 2 milliseconds), it immediately pulls up WBIAS to cut off Tr2 (this can eliminate the influence of BAT+ on input channels 1, 2, etc. through Tr2, R3, R4); then all input analog detection ports (MCU-AD1, MCU-AD2 and all other detection ports) are accurately sampled at the same time, and event tasks are processed after sampling. After the processing is completed, it enters the deep sleep state again.

[0029] Please refer again Figure 2, which is the second embodiment of the multi-channel analog input detection circuit with trigger wake-up, comprising: at least one external signal input channel module, the external signal input channel modules are electrically connected to the detection wake-up module, the detection wake-up module comprises: MCU, the MCU is used to detect and read the detection signal of the external signal input channel module, the MCU is also electrically connected to the LDO module, the LDO module is electrically connected to a level holding module, the level holding module keeps the power supply voltage in a high level state, so that the WAKE1 port is in an invalid state (the port is set to a low level and is valid), when the MCU is in deep sleep, the level holding module keeps the WAKE1 port at a high level; when the MCU is awakened and starts to read external AD data, the WAKE1 port level is pulled low to wake up the MCU to read the external data, and the LDO module is used to power the MCU; when the external signal input channel module has a signal input, the WAKE1 port level is pulled low to directly wake up the MCU, and the MCU reads the detection signal of the external signal input channel module. In order to completely eliminate the influence of transistor Tr2 and resistor R3 on the input channel, the voltage of each BAT+ can be calibrated to completely eliminate the influence of this path. A power detection module can also be added between the MCU module and the BAT+ network. The functions are as follows: the voltage detection module performs voltage detection on the system power supply BAT+. After the microcontroller is awakened, voltage detection is performed, and then AD detection is performed on the external input channel. Finally, the influence of Tr2 and R3 on the input channel is completely eliminated through the internal data of the MCU (preliminary calibrated data, that is, the influence of BAT+ voltage changes on the input channel through the Tr2 and R3 paths) and the algorithm.

[0030] The external signal input channel module is exactly the same as the first embodiment, and also includes: a first switch, electrically connected to a sampling resistor R11 of the first switch, the other end of the sampling resistor R11 is electrically connected to the cathode end of the first diode D11, the anode end of the first diode D11 is electrically connected to a second resistor R15, the other end of the second resistor R15 is electrically connected to a power supply, wherein the node between the cathode end of the first diode D11 and the sampling resistor is also electrically connected to the cathode of the second diode D1, the anode of the second diode D1 is electrically connected to the wake-up chip U1, the node between the anode end of the first diode D11 and the second resistor R15 is also electrically connected to a third resistor R14, the other end of the third resistor R14 is electrically connected to the cathode of the voltage limiting diode VD1, the anode of the voltage limiting diode VD1 is grounded, and a voltage dividing resistor R13 is also connected in parallel to both ends of the voltage limiting diode VD1, and the node between the voltage dividing resistor R13 and the third resistor R14 is electrically connected to the I / O port of the MCU. LDO (low-dropout linear regulator) is connected to BAT+ and supplies power to the MCU. The MCU can be controlled within 20uA when in sleep mode, and the leakage current of LDO can reach within 10uA. Compared with the embodiment, the sixth resistor R2, which was originally connected to WBIAS, is changed to ground. In order to reduce the impact of BAT+ on analog detection of input channels 1 and 2 through Tr2, R3, and R4, R3 is required to be as large as possible (the purpose is to minimize the impact of R3 and Tr2 on the detection accuracy of the input channel), and it is half an order of magnitude larger than the 12V-SW to ground resistance in each input channel, so that the impact of BAT+ can be minimized.

[0031] The cathode terminal of the first diode D11 is further connected in series with at least one second switch, and a sampling resistor is further connected in series between the second switch and the cathode terminal of the first diode D11.

[0032] In the second embodiment, the control strategy of the multi-channel analog input detection circuit with trigger wake-up is:

[0033] First, all external switches SW1 and SW2 are in open circuit (high impedance state), which is the default state; the WAKE1 port of the MCU defaults to the input interrupt wake-up port state, and the low level is valid. The default state of the MCU is the sleep state, that is, WAKE1 is high level; when the external switch SW1 or SW2 (or any other channel in the multi-channel) is switched to any gear (for example, it is linked to R12), WAKE1 is pulled to a low level to wake up the MCU; after the MCU wakes up (generally within 2 milliseconds), all input analog detection ports (MCU-AD1, MCU-AD2 and all other detection ports) are accurately sampled at the same time, and event tasks are processed after sampling. After the processing is completed, it enters the deep sleep state again. The LDO module itself has the characteristics of extremely low power consumption. When the MCU is in deep sleep, the LDO module is in a low-power standby state.

[0034] Compared with the prior art, the embodiment of the present invention provides a multi-channel analog input detection circuit with trigger wake-up, which solves the problem that when there are one or more AD (analog) signal input detections, when the single-chip microcomputer enters the sleep state, this analog (or switch) input signal can wake up the single-chip microcomputer through the interrupt wake-up port of the single-chip microcomputer, enter the normal standby state, and then the single-chip microcomputer detects this analog input signal again; when there is no input, the system is in a deep sleep state, thereby ensuring the lowest sleep power consumption of the entire system (below 80uA); and the single-chip microcomputer I / O resources used are minimal, the circuit is simple, and the system strategy is simple.

[0035] Those of ordinary skill in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in terms of function in the above description. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0036] In the several embodiments provided by the present invention, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of each unit is only a logical function division, and there may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed.

[0037] The steps in the method of the embodiment of the present invention can be adjusted in order, combined and deleted according to actual needs. The units in the device of the embodiment of the present invention can be combined, divided and deleted according to actual needs. In addition, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0038] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a storage medium. Based on this understanding, the technical solution of the present invention is essentially or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions for a computer device (which can be a personal computer, terminal, or network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention.

[0039] The above contents are only preferred embodiments of the present invention and are not intended to limit the implementation scheme of the present invention. A person skilled in the art can easily make corresponding changes or modifications based on the main concept and spirit of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope required by the claims.

Claims

1. A multi-channel analog input detection circuit with trigger wake-up, characterized in that: include: At least one external signal input channel module, the external signal input channel modules are all electrically connected to the detection and awakening module, the detection and awakening module includes: MCU, the MCU is used to read the detection signal of the external signal input channel module, the MCU is also electrically connected to the awakening chip U1, the awakening chip U1 is controlled to be connected and disconnected with the external power supply through a switch circuit module, the switch circuit module is electrically connected to the external signal input channel module; when the external signal input channel module has a signal input, the switch circuit module is turned on and triggers the awakening chip U1, the awakening chip U1 wakes up the MCU, and the MCU reads the detection signal of the external signal input channel module, the external signal input channel module includes: a first switch, electrically connected to the sampling resistor of the first switch, the other end of the sampling resistor is electrically connected to the cathode end of the first diode, the anode end of the first diode is electrically connected to a second resistor, the other end of the second resistor is electrically connected to the power supply, wherein the node between the cathode end of the first diode and the sampling resistor is also electrically connected to the cathode of the second diode, the anode end of the second diode is electrically connected to the cathode of the second diode, and the cathode of the second diode is electrically connected to the cathode of the second diode. The positive electrode is electrically connected to the wake-up chip U1, the node between the positive end of the first diode and the second resistor is also electrically connected to the third resistor, the other end of the third resistor is electrically connected to the negative electrode of the voltage limiting diode, the positive electrode of the voltage limiting diode is grounded, the two electrodes of the voltage limiting diode are also connected in parallel with a voltage dividing resistor, the node between the voltage dividing resistor and the third resistor is electrically connected to the I / O port of the MCU, the negative end of the first diode is also connected in series with at least one second switch, and a sampling resistor is also connected in series between the second switch and the negative end of the first diode. The model of the wake-up chip U1 is: UJA1078ATW / 5V or UJA1075ATW / 5V, and the switch circuit module includes: a fourth resistor electrically connected to the external signal input channel module, the other end of the fourth resistor is electrically connected to the collector of the transistor, the emitter of the transistor is electrically connected to the positive electrode of the external power supply, and a fifth resistor is also connected in series between the base of the transistor and the positive electrode of the external power supply. The node between the fifth resistor and the base of the transistor is also electrically connected to a sixth resistor, and the other end of the sixth resistor is electrically connected to the WB of the wake-up chip U1. I AS pin, the positive terminal of the second diode is further connected in series with a seventh resistor, and the other end of the seventh resistor is electrically connected to the wake-up chip U1.

2. A multi-channel analog input detection circuit with trigger wake-up, characterized in that: include: At least one external signal input channel module, the external signal input channel modules are all electrically connected to the detection wake-up module, the detection wake-up module includes: an MCU, the MCU is used to read the detection signal of the external signal input channel module, the MCU is also electrically connected to the LDO module, the LDO module is electrically connected to the level holding module, the LDO module supplies power to the MCU, and the level holding module keeps the MCU wake-up port level high in the deep sleep state of the MCU; when the external signal input channel module has a signal input, the MCU wake-up port level is pulled down to wake up the MCU, and the MCU reads the detection signal of the external signal input channel module, the external signal input channel module includes: a first switch, a sampling resistor electrically connected to the first switch, and another sampling resistor The end is electrically connected to the cathode end of the first diode, the anode end of the first diode is electrically connected to a second resistor, and the other end of the second resistor is electrically connected to the power supply, wherein the node between the cathode end of the first diode and the sampling resistor is also electrically connected to the cathode of the second diode, the anode of the second diode is electrically connected to the wake-up chip U1, the node between the anode end of the first diode and the second resistor is also electrically connected to the third resistor, the other end of the third resistor is electrically connected to the cathode of the voltage limiting diode, the anode of the voltage limiting diode is grounded, a voltage dividing resistor is also connected in parallel at both ends of the voltage limiting diode, the node between the voltage dividing resistor and the third resistor is electrically connected to the I / O port of the MCU, the cathode end of the first diode is also connected in series with at least one second switch, and a sampling resistor is also connected in series between the second switch and the cathode end of the first diode.

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