Multi-channel fan rotating speed monitoring circuit and method

Abstract

The invention discloses a multi-channel fan rotating speed monitoring circuit and method, relates to the technical field of industrial control, and aims at solving the problems that in the prior art, a fan rotating speed monitoring circuit is complex, high in cost, large in resource occupancy rate and the like. The circuit comprises a pulse feedback circuit, a channel selection circuit and a monitoring control circuit. Wherein one end of the pulse feedback circuit is connected with an external multi-channel fan; the other end of the pulse feedback circuit is connected with one end of the channel selection circuit; and the other end of the channel selection circuit is connected with the monitoring control circuit. Therefore, compared with the prior art, the circuit has the advantages of being simple and flexible in overall design, low in cost, high in expandability and the like.

Description

Technical Field

[0001] The present application relates to the field of industrial control technology and provides a multi-channel fan speed monitoring circuit and method. Background Art

[0002] With the rise of artificial intelligence, especially the continuous updating and iteration of computing chips, the development trend of electronic devices is becoming more and more integrated, miniaturized and portable. At the same time, the power density of chips and devices has increased exponentially. Therefore, heat dissipation has gradually become a top priority in the design of electronic equipment.

[0003] In the prior art, air cooling is often used for heat dissipation. However, when the fan is continuously working at a high speed, its working performance will decline or even fail, which will lead to a decrease in the heat dissipation of the equipment, which directly threatens the performance and safety of the equipment. The performance of the fan is directly reflected in its speed, so real-time monitoring of the fan speed is very important for the health of the entire industrial equipment. However, fan heat dissipation is only an auxiliary function compared to the main function of the equipment, so in hardware design, it is not desirable for this part of the circuit to be too complicated and costly, and in software design, it is not desirable for this part of the function to occupy too much controller resources and time.

[0004] Therefore, how to design a simple and low-cost fan speed monitoring circuit has become a problem that needs to be solved urgently. Summary of the invention

[0005] The present application provides a multi-channel fan speed monitoring circuit and method, which are used to solve the problems of fan speed monitoring circuits being relatively complex, high cost, and high resource occupancy in the prior art.

[0006] On the one hand, a multi-channel fan speed monitoring circuit is provided, the circuit comprising a pulse feedback circuit, a channel selection circuit and a monitoring control circuit;

[0007] Among them, one end of the pulse feedback circuit is connected to the external multi-channel fan; the other end of the pulse feedback circuit is connected to one end of the channel selection circuit; and the other end of the channel selection circuit is connected to the monitoring control circuit.

[0008] Optionally, the circuit further includes a level conversion circuit;

[0009] Among them, one end of the level conversion circuit is connected to the monitoring control circuit; the other end of the level conversion circuit is connected to the pulse feedback circuit.

[0010] Optionally, the pulse feedback circuit includes four pulse feedback units, and each pulse feedback unit includes a field effect transistor MOS and a first resistor;

[0011] Among them, for any pulse feedback unit, the S pole of the field effect tube MOS of any pulse feedback unit is connected to the external fan; the S pole of the field effect tube MOS of any pulse feedback unit is connected to the working level of 5V through the first resistor of any pulse feedback unit; the D pole of the field effect tube MOS of any pulse feedback unit is connected to one end of the level conversion circuit; the G pole of the field effect tube MOS of any pulse feedback unit is connected to one end of the channel selection circuit.

[0012] Optionally, the D electrodes of the MOS field effect transistors of the four pulse feedback units are connected together to form a line-and-circuit.

[0013] Optionally, the channel selection circuit includes three channel selection units, and each channel selection unit includes a field effect transistor MOS and a second resistor;

[0014] Among them, for any channel selection unit, the S pole of the field effect tube MOS of any channel selection unit is grounded; the D pole of the field effect tube MOS of any channel selection unit is connected to one end of the pulse feedback circuit; the G pole of the field effect tube MOS of any channel selection unit is connected to the monitoring control circuit, and the G pole of the field effect tube MOS of any channel selection unit is connected to the working level of 3.3V through the second resistor of any channel selection unit.

[0015] Optionally, the level conversion circuit includes a field effect transistor MOS, a third resistor and a fourth resistor;

[0016] Among them, the S pole of the MOS field effect tube is grounded; the D pole of the MOS field effect tube is connected to the working level of 3.3V through the third resistor; the D pole of the MOS field effect tube is connected to the monitoring control circuit; the G pole of the MOS field effect tube is connected to the working level of 5V through the fourth resistor; the G pole of the MOS field effect tube is connected to one end of the pulse feedback circuit.

[0017] Optionally, the monitoring control circuit is an STM32F103RCT6 ARM single-chip microcomputer, and the field effect tube MOS model is 2N7002.

[0018] On the one hand, a method for monitoring the speed of multiple fans is provided, the method comprising:

[0019] The pulse feedback circuit is used to obtain the pulses generated by the external multi-channel fans;

[0020] The channel selection circuit is used to select a channel, determine a target fan for feedback pulses, and feed back the pulses of the target fan to the monitoring control circuit through the selected channel; wherein one channel corresponds to one fan;

[0021] The monitoring control circuit is used to perform pulse calculation on the received pulses to determine the rotation speed of the target fan.

[0022] In one aspect, a storage medium is provided, on which computer program instructions are stored, and when the computer program instructions are executed by a processor, any of the above methods is implemented.

[0023] Compared with the prior art, the beneficial effects of this application are:

[0024] The present application proposes a multi-channel fan speed monitoring circuit. Specifically, the circuit includes a pulse feedback circuit, a channel selection circuit and a monitoring control circuit; wherein one end of the pulse feedback circuit is connected to an external multi-channel fan; the other end of the pulse feedback circuit is connected to one end of the channel selection circuit; the other end of the channel selection circuit is connected to the monitoring control circuit. It can be seen that the multi-channel fan speed monitoring circuit of the present application has the advantages of simple design, small layout area and strong scalability. Therefore, it can be widely used in high-power industrial control industry, high-energy consumption automotive electronics industry, and high-power density artificial intelligence industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the related technologies, the drawings required for use in the embodiments or the related technical descriptions are briefly introduced below. Obviously, the drawings described below are only the embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0026] Figure 1 A schematic diagram of a structure of a multi-channel fan speed monitoring circuit provided in an embodiment of the present application;

[0027] Figure 2 Another structural schematic diagram of a multi-channel fan speed monitoring circuit provided in an embodiment of the present application;

[0028] Figure 3 A schematic diagram of the specific principle of a multi-channel fan speed monitoring circuit provided in an embodiment of the present application;

[0029] Figure 4 A schematic diagram of a flow chart of a method for monitoring the speed of multiple fans provided in an embodiment of the present application. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical scheme and advantages of the present application clearer, the technical scheme in the embodiment of the present application will be clearly and completely described below in conjunction with the drawings in the embodiment of the present application. Obviously, the described embodiment is only a part of the embodiment of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present application. In the absence of conflict, the embodiments in the present application and the features in the embodiments can be combined with each other arbitrarily. In addition, although the logical order is shown in the flow chart, in some cases, the steps shown or described can be performed in an order different from that here.

[0031] With the rise of artificial intelligence, especially the continuous updating and iteration of computing chips, the development trend of electronic devices is becoming more and more integrated, miniaturized and portable. At the same time, the power density of chips and devices has increased exponentially. Therefore, heat dissipation has gradually become a top priority in the design of electronic equipment.

[0032] In the prior art, air cooling is often used for heat dissipation. However, when the fan is continuously working at a high speed, its working performance will decline or even fail, which will lead to a decrease in the heat dissipation of the equipment, which directly threatens the performance and safety of the equipment. The performance of the fan is directly reflected in its speed, so real-time monitoring of the fan speed is very important for the health of the entire industrial equipment. However, fan heat dissipation is only an auxiliary function compared to the main function of the equipment, so in hardware design, it is not desirable for this part of the circuit to be too complicated and costly, and in software design, it is not desirable for this part of the function to occupy too much controller resources and time.

[0033] Based on this, the embodiment of the present application provides a multi-channel fan speed monitoring circuit, specifically, the circuit includes a pulse feedback circuit, a channel selection circuit and a monitoring control circuit; wherein one end of the pulse feedback circuit is connected to an external multi-channel fan; the other end of the pulse feedback circuit is connected to one end of the channel selection circuit; the other end of the channel selection circuit is connected to the monitoring control circuit. It can be seen that the multi-channel fan speed monitoring circuit of the present application has the advantages of simple design, small layout area and strong scalability. Therefore, it can be widely used in high-power industrial control industry, high-energy consumption automotive electronics industry, and high-power density artificial intelligence industry.

[0034] After introducing the design ideas of the embodiments of the present application, the following briefly introduces the application scenarios to which the technical solutions of the embodiments of the present application can be applied. It should be noted that the application scenarios introduced below are only used to illustrate the embodiments of the present application and are not limited. In the specific implementation process, the technical solutions provided by the embodiments of the present application can be flexibly applied according to actual needs.

[0035] like Figure 1 As shown, it is a structural schematic diagram of a multi-channel fan speed monitoring circuit provided in an embodiment of the present application, and the multi-channel fan speed monitoring circuit includes a pulse feedback circuit, a channel selection circuit and a monitoring control circuit; wherein, one end of the pulse feedback circuit is connected to an external multi-channel fan; the other end of the pulse feedback circuit is connected to one end of the channel selection circuit; the other end of the channel selection circuit is connected to the monitoring control circuit.

[0036] In a possible implementation, since the level of the fan output and the operating voltage of the monitoring control circuit may be inconsistent, for example, the level of the fan output is 5V, and the operating voltage of the monitoring control circuit MCU GPIO is 3.3V, therefore, in the embodiment of the present application, a level conversion circuit is also designed in the multi-channel fan speed monitoring circuit, such as Figure 2 As shown, another structural schematic diagram of the multi-channel fan speed monitoring circuit provided in the embodiment of the present application is shown, that is, the multi-channel fan speed monitoring circuit can also include a level conversion circuit; wherein one end of the level conversion circuit can be connected to the monitoring control circuit; and the other end of the level conversion circuit can be connected to the pulse feedback circuit. Furthermore, based on this level conversion circuit, 5V can be converted into 3.3V.

[0037] In a possible implementation, the rotation speeds of the four fans are monitored. In the embodiment of the present application, Figure 3 As shown, it is a schematic diagram of the specific principle of the multi-channel fan speed monitoring circuit provided in the embodiment of the present application. The pulse feedback circuit may include four pulse feedback units, and each pulse feedback unit includes a field effect transistor MOS and a first resistor;

[0038] Among them, for any pulse feedback unit, the S pole of the field effect tube MOS of any pulse feedback unit can be connected to an external fan; the S pole of the field effect tube MOS of any pulse feedback unit can be connected to a 5V working level through the first resistor of any pulse feedback unit; the D pole of the field effect tube MOS of any pulse feedback unit can be connected to one end of the level conversion circuit; the G pole of the field effect tube MOS of any pulse feedback unit can be connected to one end of the channel selection circuit.

[0039] Specifically, Figure 3As shown, the pulse feedback circuit includes four pulse feedback units, namely, pulse feedback unit 1, pulse feedback unit 2, pulse feedback unit 3 and pulse feedback unit 4, and these four pulse feedback units correspond to fans 1 to 4 one by one. Among them, pulse feedback unit 1 has a field effect tube MOS Q2 and a resistor, pulse feedback unit 2 has a field effect tube MOS Q3 and a resistor, pulse feedback unit 3 has a field effect tube MOS Q4 and a resistor, and pulse feedback unit 4 has a field effect tube MOS Q5 and a resistor.

[0040] Here we take the pulse feedback unit 4 as an example. Figure 3 As shown, the S pole of the MOS Q5 is not only connected to the external fan, but also connected to the 5V working level through the first resistor; the D pole of the MOS is connected to one end of the level conversion circuit; and the G pole of the MOS is connected to one end of the channel selection circuit.

[0041] In one possible implementation, in order to reduce the number of logic gates used, simplify circuit design, reduce costs, and improve the circuit's collaborative working ability, reliability, and stability, in an embodiment of the present application, the D poles of the MOS field effect transistors of the four pulse feedback units of the pulse feedback circuit can be connected together to form a line-and circuit.

[0042] In a possible implementation, in order to simplify circuit design and reduce costs, in the embodiment of the present application, the channel selection circuit may include three channel selection units, and each channel selection unit includes a field effect transistor MOS and a second resistor;

[0043] Among them, for any channel selection unit, the S pole of the field effect tube MOS of any channel selection unit can be grounded; the D pole of the field effect tube MOS of any channel selection unit can be connected to one end of the pulse feedback circuit; the G pole of the field effect tube MOS of any channel selection unit can be connected to the monitoring control circuit, and the G pole of the field effect tube MOS of any channel selection unit can be connected to the working level of 3.3V through the second resistor of any channel selection unit.

[0044] Specifically, Figure 3 As shown, the channel selection circuit includes three pulse feedback units, namely, channel selection unit 1, channel selection unit 2 and channel selection unit 3. Among them, channel selection unit 1 has a field effect transistor MOS Q6 and a resistor, channel selection unit 2 has a field effect transistor MOS Q7 and a resistor, and channel selection unit 3 has a field effect transistor MOS Q8 and a resistor.

[0045] In practical applications, such as Figure 3As shown, FETs Q3, Q4 and Q5 can be directly controlled by the monitoring control circuit MCU GPIO, while the on and off of FET Q2 is determined by the result of the AND operation of FETs Q6, Q7 and Q8. That is, when one of FETs Q6, Q7 and Q8 is turned on, FET Q2 is not turned on; when all of FETs Q6, Q7 and Q8 are not turned on, FET Q2 is turned on. Based on this, the monitoring control circuit MCU can select the pulses of the fan feedback to be read in a time-sharing manner.

[0046] In a possible implementation manner, in order to simplify circuit design and reduce costs, in the embodiment of the present application, the level conversion circuit may include a field effect transistor MOS, a third resistor and a fourth resistor;

[0047] Among them, Figure 3 As shown, the S pole of the MOS field effect tube can be grounded; the D pole of the MOS field effect tube can be connected to the working level of 3.3V through the third resistor; the D pole of the MOS field effect tube can be connected to the monitoring control circuit; the G pole of the MOS field effect tube can be connected to the working level of 5V through the fourth resistor; the G pole of the MOS field effect tube can be connected to one end of the pulse feedback circuit.

[0048] In a possible implementation, in order to simplify the circuit design and reduce costs, in the embodiment of the present application, the monitoring control circuit can use ST's STM32F103RCT6 ARM single-chip microcomputer. The STM32F103 single-chip microcomputer specifically adopts the Cortex-M3 core, and the CPU has a maximum speed of 72MHz. And this type of MCU not only has 16KB~1MB Flash, a variety of control peripherals, USB full-speed interface and CAN. In addition, this type of MCU is also widely used in the control field, with abundant development resources and low price cost.

[0049] In the embodiment of the present application, in order to reduce costs, the MOS model of the pulse feedback circuit, the channel selection circuit and the level conversion circuit can all be 2N7002, wherein the specific parameters of the 2N7002 field effect tube are: MAX VDS=60V, MAX ID=300mA RDSon=2.8Ω.

[0050] In addition, in order to reduce costs, each first resistor in the pulse feedback circuit, each second resistor in the channel selection circuit, and the third resistor and the fourth resistor in the level conversion circuit can be selected as resistors of the same model and the same resistance value.

[0051] Based on the same inventive concept, the present application embodiment provides a method for monitoring the speed of multiple fans. Figure 4FIG. 1 is a flow chart of a method for monitoring the speed of multiple fans provided in an embodiment of the present application. The method can be performed by Figure 1-Figure 3 The method can be executed by any of the multi-channel fan speed monitoring circuits. Specifically, the process of the method is described as follows.

[0052] Step 401: using a pulse feedback circuit to obtain pulses generated by an external multi-channel fan.

[0053] like Figure 3 As shown, after the fan rotates, each pulse feedback unit in the pulse feedback circuit can be used to respectively obtain the pulses generated by the external multi-channel fans.

[0054] Step 402: Use a channel selection circuit to perform channel selection, determine a target fan for feedback pulses, and feed back the pulses of the target fan to the monitoring control circuit through the selected channel.

[0055] In the embodiment of the present application, one channel corresponds to one fan.

[0056] Specifically, first, the on-off state of the four MOS field effect transistors in the pulse feedback circuit can be determined according to the control signal of the monitoring control circuit and the on-off state of the three MOS field effect transistors in the channel selection circuit, such as Figure 3 As shown, the field effect tubes Q3, Q4 and Q5 can be directly controlled by the monitoring control circuit MCU GPIO, and the on and off of the field effect tube Q2 is determined by the result of the AND of the field effect tubes Q6, Q7 and Q8. That is, when one of the field effect tubes Q6, Q7 and Q8 is turned on, the field effect tube Q2 is not turned on; when the field effect tubes Q6, Q7 and Q8 are all turned off, the field effect tube Q2 is turned on; then, the target fan of the feedback pulse can be determined according to the on and off states of the four field effect tubes MOS in the pulse feedback circuit. For example, when the field effect tube Q2 is turned on, the fan 1 corresponding to the field effect tube Q2 is the target fan; finally, the pulse of the target fan can be fed back to the monitoring control circuit through the corresponding channel.

[0057] Step 403: Using a monitoring control circuit to perform pulse calculation on the received pulses to determine the rotation speed of the target fan.

[0058] Specifically, when the channel selection circuit feeds back a pulse to the external interrupt pin of the monitoring control circuit, the monitoring control circuit can be used to receive the pulse fed back by the channel selection circuit; then, the received pulse is calculated based on the timer inside the monitoring control circuit, thereby determining the speed of the target fan.

[0059] In summary, in the embodiment of the present application, the external multi-channel fan speed feedback pulse can be passed through the interface MOS tube of the pulse feedback circuit, and the channel MOS tube of the channel selection circuit is turned on by the monitoring control circuit MCU, and then input to the external interrupt pin of the monitoring control circuit MCU, and the timer timer inside the monitoring control circuit MCU is used as the time reference, and then the pulse count of the external multi-channel fan in the unit time is counted. Therefore, compared with the prior art, the present application uses a monitoring control unit with a low-cost ARM single-chip microcomputer as the core control device, a level conversion circuit composed of a MOS tube, a channel selection circuit and a pulse feedback circuit. The application circuit is simple in design, the device type is single, the layout area is small, the MCU pins and resources are extremely small, the versatility and expansibility are strong, and the software is provided with a control pin for programmable selection of time-sharing and branching to read the fan speed, which can avoid occupying MCU resources. Therefore, it can be widely used in high-power industrial control industries, high-energy consumption automotive electronics industries, and high-power density artificial intelligence industries.

[0060] In some possible implementations, various aspects of the method provided in the present application may also be implemented in the form of a program part, which includes a program code. When the program part is run on a computer device, the program code is used to enable the computer device to execute the steps of the method according to various exemplary embodiments of the present application described above in this specification. For example, the computer device may execute the following steps: Figure 4 The method performed in the illustrated embodiment.

[0061] Those skilled in the art can understand that: all or part of the steps of the above method embodiment can be completed by hardware related to program instructions, the aforementioned program can be stored in a computer-readable storage medium, and when the program is executed, the steps of the above method embodiment are executed; and the aforementioned storage medium includes: various media that can store program codes, such as mobile storage devices, read-only memory (ROM), random access memory (RAM), magnetic disks or optical disks. Alternatively, if the above integrated unit of the present invention is implemented in the form of a software function module and sold or used as an independent part, it can also be stored in a computer-readable storage medium. Based on such an understanding, the technical solution of the embodiment of the present invention can be essentially or in other words, the part that contributes to the prior art can be embodied in the form of a software part, which is stored in a storage medium and includes several instructions for a computer device (which can be a personal computer, a server or a network device, etc.) to execute all or part of the methods described in various embodiments of the present invention. And the aforementioned storage medium includes: various media that can store program codes, such as mobile storage devices, ROM, RAM, magnetic disks or optical disks.

[0062] Although the preferred embodiments of the present application have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present application.

[0063] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. A multi-channel fan speed monitoring circuit, characterized in that: The circuit includes a pulse feedback circuit, a channel selection circuit and a monitoring control circuit; Among them, one end of the pulse feedback circuit is connected to the external multi-channel fan; the other end of the pulse feedback circuit is connected to one end of the channel selection circuit; and the other end of the channel selection circuit is connected to the monitoring control circuit.

2. The multi-channel fan speed monitoring circuit as claimed in claim 1, characterized in that: The circuit also includes a level conversion circuit; Among them, one end of the level conversion circuit is connected to the monitoring control circuit; the other end of the level conversion circuit is connected to the pulse feedback circuit.

3. The multi-channel fan speed monitoring circuit as claimed in claim 2, characterized in that: The pulse feedback circuit includes four pulse feedback units, and each pulse feedback unit includes a field effect transistor MOS and a first resistor; Among them, for any pulse feedback unit, the S pole of the field effect tube MOS of any pulse feedback unit is connected to the external fan; the S pole of the field effect tube MOS of any pulse feedback unit is connected to the working level of 5V through the first resistor of any pulse feedback unit; the D pole of the field effect tube MOS of any pulse feedback unit is connected to one end of the level conversion circuit; the G pole of the field effect tube MOS of any pulse feedback unit is connected to one end of the channel selection circuit.

4. The multi-channel fan speed monitoring circuit as claimed in claim 3, characterized in that: The D electrodes of the MOS field effect tubes of the four pulse feedback units are connected together to form a line-and-circuit.

5. The multi-channel fan speed monitoring circuit as claimed in claim 2, characterized in that: The channel selection circuit includes three channel selection units, and each channel selection unit includes a field effect transistor MOS and a second resistor; Among them, for any channel selection unit, the S pole of the field effect tube MOS of any channel selection unit is grounded; the D pole of the field effect tube MOS of any channel selection unit is connected to one end of the pulse feedback circuit; the G pole of the field effect tube MOS of any channel selection unit is connected to the monitoring control circuit, and the G pole of the field effect tube MOS of any channel selection unit is connected to the working level of 3.3V through the second resistor of any channel selection unit.

6. The multi-channel fan speed monitoring circuit as claimed in claim 2, characterized in that: The level conversion circuit includes a field effect transistor MOS, a third resistor and a fourth resistor; Among them, the S pole of the MOS field effect tube is grounded; the D pole of the MOS field effect tube is connected to the working level of 3.3V through the third resistor; the D pole of the MOS field effect tube is connected to the monitoring control circuit; the G pole of the MOS field effect tube is connected to the working level of 5V through the fourth resistor; the G pole of the MOS field effect tube is connected to one end of the pulse feedback circuit.

7. The multi-channel fan speed monitoring circuit according to any one of claims 3 to 6, characterized in that: The monitoring control circuit is an STM32F103RCT6 ARM single chip microcomputer, and the field effect tube MOS model is 2N7002.

8. A method for monitoring the speed of multiple fans, characterized in that: Applicable to a multi-channel fan speed monitoring circuit according to any one of claims 1 to 7; the method comprises: The pulse feedback circuit is used to obtain the pulses generated by the external multi-channel fans; The channel selection circuit is used to perform channel selection, determine the target fan of the feedback pulse, and feed back the pulse of the target fan to the monitoring control circuit through the selected channel; wherein one channel corresponds to one fan; The monitoring control circuit is used to perform pulse calculation on the received pulses to determine the rotation speed of the target fan.

9. The method according to claim 8, characterized in that The step of using the channel selection circuit to select a channel, determining a target fan of a feedback pulse, and feeding back the pulse of the target fan to the monitoring control circuit through the selected channel includes: Determine the on-off state of the four field effect transistors MOS in the pulse feedback circuit according to the control signal of the monitoring control circuit and the on-off state of the three field effect transistors MOS in the channel selection circuit; Determine the target fan of the feedback pulse according to the on / off status of four field effect transistors MOS in the pulse feedback circuit; The pulse of the target fan is fed back to the monitoring control circuit through the corresponding channel.

10. The method according to claim 8, characterized in that The step of using the monitoring control circuit to perform pulse calculation on the received pulses to determine the rotation speed of the target fan includes: Using the monitoring control circuit to receive the pulse fed back by the channel selection circuit; The timer inside the monitoring control circuit is used as a time reference to perform pulse calculation on the received pulses to determine the rotation speed of the target fan.

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