Function multiplexing circuit and electric appliance

Abstract

The utility model relates to the field of power electronics, disclose function multiplexing circuit and electrical equipment, this function multiplexing circuit, include: LED lamp control circuit and buzzer control circuit, wherein, LED lamp control circuit includes first LED lamp and second LED lamp, first LED lamp and second LED lamp reverse parallel connection after one end external first level signal, the other end external second level signal, buzzer control circuit includes: buzzer, first control circuit and second control circuit, wherein, the control end of first control circuit external second level signal, first end ground, second end with the first end connection of buzzer, the control end of second control circuit external first level signal, first end external power, second end with the second end connection of buzzer, the utility model realizes 2 LED lamps and 1 buzzer's function multiplexing, has improved user use experience, has saved an IO mouth resource, has reduced the chip selection cost.

Description

Technical Field

[0001] This utility model relates to the field of power electronics technology, specifically to functional multiplexing circuits and electrical equipment. Background Technology

[0002] In products that require both LED displays and buzzers, such as household appliances like fans, electric heaters, and humidifiers, driving two LEDs and one buzzer typically requires three chip I / O ports. Each chip I / O port controls one LED and one buzzer independently. However, sometimes the chip's I / O port resources are insufficient, necessitating replacement with a chip that has more I / O port resources, thus increasing costs. Utility Model Content

[0003] In view of this, the present invention provides a functional multiplexing circuit and electrical equipment to solve the problem in the related technology that driving two LED lights and one buzzer requires three chip I / O ports, which increases the cost of chip selection.

[0004] In a first aspect, this utility model provides a functional multiplexing circuit, including: an LED lamp control circuit and a buzzer control circuit, wherein the LED lamp control circuit includes a first LED lamp and a second LED lamp, and the first LED lamp and the second LED lamp are connected in reverse parallel connection, with one end externally connected to a first level signal and the other end externally connected to a second level signal;

[0005] The buzzer control circuit includes: a buzzer, a first control circuit, and a second control circuit. The control terminal of the first control circuit is externally connected to the second level signal, the first terminal is grounded, and the second terminal is connected to the first terminal of the buzzer. The control terminal of the second control circuit is externally connected to the first level signal, the first terminal is externally connected to a power supply, and the second terminal is connected to the second terminal of the buzzer.

[0006] This invention utilizes two level signals to control both the LED light control circuit and the buzzer control circuit. Each level signal can independently control one LED light to turn on or off. The two level signals alternately output high and low level signals, which generates an alternating voltage across the buzzer. Due to its piezoelectric effect, the buzzer produces a buzzing sound. Thus, by using two level signals, the functions of two LED lights and one buzzer are multiplexed, improving the user experience. Furthermore, since the two level signals only require two I / O resources, one I / O port resource can be saved, reducing the requirements for selecting I / O port resources for the external control chip and lowering the chip selection cost.

[0007] In one optional embodiment, the function multiplexing circuit further includes: a controller, wherein a first output port of the controller is connected to one end of the first LED and the control terminal of the second control circuit respectively, for outputting the first level signal; and a second output port of the controller is connected to the other end of the first LED and the control terminal of the first control circuit respectively, for outputting the second level signal.

[0008] This invention drives the LED light control circuit and the buzzer control circuit by outputting two level signals from the controller. It only requires two I / O ports of the controller, reducing the cost of controller selection and thus reducing the cost of the entire function multiplexing circuit.

[0009] In one optional implementation, the first control circuit includes: a first controlled switch, wherein the control terminal of the first controlled switch is externally connected to the second level signal, the first terminal is grounded, and the second terminal is connected to the first terminal of the buzzer;

[0010] The first controlled switch is turned on when the second level signal is high.

[0011] The first controlled switch is turned off when the second level signal is low.

[0012] This invention controls the voltage connected to the first terminal of the buzzer by using a level signal to drive a controlled switch, thereby achieving automatic control of the voltage connected to the second terminal of the buzzer and improving control efficiency and stability.

[0013] In one optional embodiment, the first control circuit further includes: a first resistor and a second resistor, wherein one end of the first resistor is externally connected to the second level signal, and the other end is connected to one end of the second resistor and the control terminal of the first controlled switch, respectively.

[0014] The other end of the second resistor is connected to the first end of the first controlled switch.

[0015] This invention uses a first resistor and a second resistor to form the peripheral circuit of the first controlled switch, which can ensure the reliable and stable operation of the first controlled switch.

[0016] In one optional embodiment, the second control circuit includes: a second controlled switch and a third controlled switch, wherein the control terminal of the second controlled switch is externally connected to the first level signal, the first terminal is grounded, the second terminal is connected to the control terminal of the third controlled switch, the first terminal of the third controlled switch is connected to the second terminal of the buzzer, and the second terminal is externally connected to the power supply;

[0017] When the first level signal is high, the second controlled switch is turned on, and the third controlled switch is turned on;

[0018] When the first level signal is low, the second controlled switch is turned off, and the third controlled switch is also turned off.

[0019] This invention uses two controlled switches to control the voltage connected to the first terminal of the buzzer, thereby achieving automatic control of the voltage connected to the second terminal of the buzzer and improving control efficiency and stability.

[0020] In one optional embodiment, the second control circuit further includes: a third resistor, a fourth resistor, a fifth resistor, and a sixth resistor, wherein one end of the third resistor is externally connected to the first level signal, and the other end is respectively connected to one end of the fourth resistor and the control terminal of the second controlled switch;

[0021] The other end of the fourth resistor is connected to the first end of the second controlled switch;

[0022] One end of the fifth resistor is connected to the second end of the second controlled switch, and the other end is connected to the control end of the third controlled switch and one end of the sixth resistor, respectively.

[0023] The other end of the sixth resistor is connected to the power supply.

[0024] This invention uses a third resistor, a fourth resistor, a fifth resistor, and a sixth resistor to form the peripheral circuit of the second and third controlled switches, which can ensure the reliable and stable operation of the second and third controlled switches.

[0025] In one optional embodiment, the LED control circuit further includes a seventh resistor, one end of which is externally connected to the first level signal, and the other end is connected to the positive terminal of the first LED.

[0026] This invention uses a seventh resistor to limit current, preventing damage to the LED light and improving the stability of the LED light's operation.

[0027] In one alternative implementation, the first controlled switch is an NPN transistor.

[0028] This invention utilizes an NPN transistor to amplify the current, ensuring that the voltage connected to the second terminal of the buzzer meets the buzzer's operating requirements, thereby further ensuring the buzzer's reliable operation.

[0029] In one optional implementation, the second controlled switch is an NPN transistor, and the third controlled switch is a PNP transistor.

[0030] This invention utilizes both NPN and PNP transistors to amplify the current, ensuring that the voltage connected to the first terminal of the buzzer meets the buzzer's operating requirements, thereby further ensuring the buzzer's reliable operation.

[0031] Secondly, the present invention provides an electrical device, the electrical device comprising: a function multiplexing circuit as provided in the first aspect above or any corresponding embodiment thereof.

[0032] The electrical device provided by this utility model uses a function multiplexing circuit to control the LED light control circuit and the buzzer control circuit using two level signals. Each level signal can independently control one LED light to turn on or off. The two level signals alternately output high and low level signals, at which time an alternating voltage is generated at the two ends of the buzzer. The buzzer produces a buzzing sound due to its own piezoelectric effect. Thus, by using two level signals, the functions of two LED lights and one buzzer are multiplexed, which improves the user experience. Furthermore, since the two level signals only require two IO resources, one IO port resource can be saved, reducing the requirements for the selection of IO port resources of the external control chip, reducing the chip selection cost, and thus reducing the hardware cost of the entire electrical device product. Attached Figure Description

[0033] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0034] Figure 1 This is a schematic diagram of the driving circuit for dual LED lights and buzzers in related technologies;

[0035] Figure 2 This is a schematic diagram of the structure of a functional multiplexing circuit according to an embodiment of the present utility model;

[0036] Figure 3 This is a structural schematic diagram of an electrical device according to an embodiment of the present utility model. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0038] In related technologies, driving two LEDs and one buzzer typically requires three chip I / O ports, with each chip I / O port controlling one LED and one buzzer independently. However, sometimes the chip's I / O port resources are insufficient, necessitating replacement with a chip that has more resources, thus increasing costs. For example, a schematic diagram of the driving circuit for a dual-LED light and buzzer in related technologies is shown below. Figure 1 As shown, IO11 and IO12 of the chip each control one LED. When IO11 or IO12 outputs a high level, the corresponding LED D11 or D12 lights up; when IO11 or IO12 outputs a low level, the corresponding LED D11 or D12 turns off. IO13 controls buzzer BUZ1. When IO13 outputs a PWM waveform of a certain frequency, buzzer BUZ1 sounds; when IO13 outputs a low level, buzzer BUZ1 does not sound. It is evident that each LED requires one IO port to output high / low level signals to control its on / off state. Additionally, the buzzer also requires a separate IO port to output high / low level signals to drive the transistor to turn on and off, generating alternating voltages across the buzzer. The buzzer produces its sound due to its piezoelectric effect. This necessitates that the driver chip used to output the drive signals must have at least three IO ports, thus increasing the cost of selecting the driver chip.

[0039] To address the aforementioned issues, this embodiment provides a function multiplexing circuit. Figure 2 This is a schematic diagram of the functional multiplexing circuit according to an embodiment of the present utility model, as shown below. Figure 2 As shown, the function multiplexing circuit includes:

[0040] LED light control circuit 201 and buzzer control circuit 202, wherein the LED light control circuit 201 includes a first LED light D1 and a second LED light D2. The first LED light D1 and the second LED light D2 are connected in reverse parallel and one end is connected to a first level signal, and the other end is connected to a second level signal.

[0041] The buzzer control circuit 202 includes a buzzer BUZ1, a first control circuit 2021, and a second control circuit 2022. The control terminal of the first control circuit 2021 is connected to a second level signal, the first terminal is grounded, and the second terminal is connected to the first terminal of the buzzer BUZ1. The control terminal of the second control circuit 2022 is connected to a first level signal, the first terminal is connected to an external power supply VCC, and the second terminal is connected to the second terminal of the buzzer BUZ1.

[0042] This embodiment of the invention utilizes two level signals to control the LED light control circuit and the buzzer control circuit. Each level signal can independently control one LED light to turn on or off. The two level signals alternately output high and low level signals, at which time an alternating voltage is generated at the two ends of the buzzer. The buzzer produces a buzzing sound due to its own piezoelectric effect. Thus, by using two level signals, the functions of two LED lights and one buzzer are multiplexed, improving the user experience. Furthermore, since the two level signals only require two IO resources, one IO port resource can be saved, reducing the requirements for the selection of IO port resources of the external control chip and reducing the chip selection cost.

[0043] In some optional implementations, the function multiplexing circuit provided in this embodiment of the present invention further includes: a controller ( Figure 2 (not shown in the image), such as Figure 2 As shown, the first output port IO1 of the controller is connected to one end of the first LED D1 and the control terminal of the second control circuit 2022, respectively, and is used to output a first level signal; the second output port IO2 of the controller is connected to the other end of the first LED D1 and the control terminal of the first control circuit 2021, respectively, and is used to output a second level signal.

[0044] For example, the controller described above can be a driver chip such as an MCU or microcontroller, hereinafter referred to as a chip. This is only an example and is not intended to limit the invention. The power supply described above is for ensuring the normal operation of the second control circuit. The specific power supply voltage can be set according to the specific design requirements of the second control circuit, and will not be elaborated here.

[0045] This utility model embodiment drives the LED light control circuit and the buzzer control circuit by outputting two level signals from the controller. It only requires two I / O port resources of the controller, which reduces the selection cost of the controller and thus reduces the cost of the entire function multiplexing circuit.

[0046] In some alternative implementations, such as Figure 2 As shown, the first control circuit 2021 includes: a first controlled switch Q2, the control terminal of the first controlled switch Q2 is externally connected to a second level signal, the first terminal is grounded, and the second terminal is connected to the first terminal of the buzzer BUZ1;

[0047] When the second level signal is high, the first controlled switch Q2 is turned on;

[0048] When the second level signal is low, the first controlled switch Q2 is turned off.

[0049] This invention controls the voltage connected to the first terminal of the buzzer by using a level signal to drive a controlled switch, thereby achieving automatic control of the voltage connected to the second terminal of the buzzer and improving control efficiency and stability.

[0050] For example, such as Figure 2 As shown, the first controlled switch Q2 is an NPN transistor. In practical applications, the first controlled switch Q2 can also be a PMOS transistor or other switching devices, and this invention is not limited thereto.

[0051] This embodiment of the invention utilizes an NPN transistor to amplify the current, ensuring that the voltage connected to the second terminal of the buzzer meets the buzzer's operating requirements, thereby further ensuring the reliable operation of the buzzer.

[0052] Furthermore, such as Figure 2 As shown, the first control circuit 2021 further includes: a first resistor R3 and a second resistor R4, wherein one end of the first resistor R3 is externally connected to a second level signal, and the other end is connected to one end of the second resistor R4 and the control terminal of the first controlled switch Q2 respectively.

[0053] The other end of the second resistor R4 is connected to the first end of the first controlled switch Q2.

[0054] This embodiment of the invention uses a first resistor and a second resistor to form the peripheral circuit of the first controlled switch, which can ensure the reliable and stable operation of the first controlled switch.

[0055] In some alternative implementations, such as Figure 2 As shown, the second control circuit 2022 includes: a second controlled switch Q3 and a third controlled switch Q1. The control terminal of the second controlled switch Q3 is connected to a first level signal, the first terminal is grounded, and the second terminal is connected to the control terminal of the third controlled switch Q1. The first terminal of the third controlled switch Q1 is connected to the second terminal of the buzzer BUZ1, and the second terminal is connected to the external power supply VCC.

[0056] When the first level signal is high, the second controlled switch Q3 is turned on, and the third controlled switch Q1 is turned on;

[0057] When the first level signal is low, the second controlled switch Q3 is turned off, and the third controlled switch Q1 is also turned off.

[0058] This embodiment of the invention uses two controlled switches to control the voltage connected to the first terminal of the buzzer, thereby achieving automatic control of the voltage connected to the second terminal of the buzzer, improving control efficiency and stability.

[0059] For example, such as Figure 2 As shown, the second controlled switch Q3 is an NPN transistor, and the third controlled switch Q3 is a PNP transistor. In practical applications, the second controlled switch Q3 can also be a PMOS transistor or other switching device, and the third controlled switch Q1 can also be an NMOS transistor or other switching device; this invention is not limited to these.

[0060] This embodiment of the invention utilizes both NPN and PNP transistors to amplify the current, ensuring that the voltage connected to the first terminal of the buzzer meets the buzzer's operating requirements, thereby further ensuring the reliable operation of the buzzer.

[0061] Furthermore, the second control circuit 2022 mentioned above also includes: a third resistor R7, a fourth resistor R8, a fifth resistor R6 and a sixth resistor R5, wherein one end of the third resistor R7 is externally connected to a first level signal, and the other end is connected to one end of the fourth resistor R8 and the control terminal of the second controlled switch Q3 respectively.

[0062] The other end of the fourth resistor R8 is connected to the first end of the second controlled switch Q3;

[0063] One end of the fifth resistor R6 is connected to the second end of the second controlled switch Q3, and the other end is connected to the control end of the third controlled switch Q1 and one end of the sixth resistor R5.

[0064] The other end of the sixth resistor R5 is connected to the external power supply VCC.

[0065] This embodiment of the invention uses a third resistor, a fourth resistor, a fifth resistor, and a sixth resistor to form the peripheral circuit of the second and third controlled switches, which can ensure the reliable and stable operation of the second and third controlled switches.

[0066] In some alternative implementations, such as Figure 2 As shown, the LED lamp control circuit 201 also includes a seventh resistor R1, one end of which is connected to a first level signal, and the other end is connected to the positive terminal of the first LED lamp D1.

[0067] This embodiment of the invention uses a seventh resistor to limit current, preventing damage to the LED light and improving the stability of the LED light's operation.

[0068] For example, such as Figure 2 As shown, the above-mentioned function multiplexing circuit also includes an eighth resistor R2, which is connected in parallel across the buzzer BUZ1.

[0069] In this embodiment of the invention, the eighth resistor serves to limit the current and absorb voltage spikes when the buzzer BUZ1 is turned off.

[0070] The working principle and process of the functional multiplexing circuit provided in this embodiment of the present invention will be described in detail below with reference to specific application examples.

[0071] For example, such as Figure 2 As shown, the chip's IO2 is connected to the cathode of D1 and the anode of D2. The chip's IO1 is connected to R1 and then to the anode of D1 and the cathode of D2. When the anode of the LED is at a high level and the cathode is at a low level, the LED lights up. When both the anode and cathode of the LED are at a high level or a low level, the LED does not light up.

[0072] Q1 is a PNP or PMOS transistor. It conducts when the base of the PNP transistor or the gate of the PMOS transistor (i.e., the pin connected to the common terminal of R5 and R6) is low, and is cut off when it is high. Q2 and Q3 are NPN or NMOS transistors. They conduct when the base of the PNP transistor or the gate of the PMOS transistor (i.e., the pin connected to the common terminal of R7 and R8, R3 and R4) is high, and are cut off when they are low. R3, R6, and R7 act as current-limiting resistors, and R4 and R8 act as pull-down resistors, providing a stable low level to Q2 and Q3 when there is no input to IO1 and IO2. R5 acts as a pull-up resistor, providing a stable high level to Q1 when there is no input to IO1. The buzzer BUZ1 sounds when there is an alternating voltage across it, and does not sound when the voltage across it is simultaneously high or simultaneously low. R2 serves to limit the current and absorb voltage spikes when the buzzer BUZ1 is turned off.

[0073] The buzzer mentioned in this embodiment of the invention refers to a passive buzzer. The frequency of the buzzer's drive signal is generally fixed at 2000Hz or 4000Hz, serving as a "beep-beep" alert tone without pitch variation. However, adjusting the drive frequency can adjust the pitch. Drive frequencies higher than the persistence of vision in the human eye are also typically 2000Hz or 4000Hz, which meets the pitch requirements of the buzzer.

[0074] When IO1 outputs a high level, Q3 is turned on, which in turn turns Q1 on; when IO1 outputs a low level, Q3 is turned off, which in turn turns Q1 off. When IO2 outputs a high level, Q2 is turned on; when IO2 outputs a low level, Q1 is turned off.

[0075] When both Q1 and Q2 are on, buzzer BUZ1 is on. When only one of Q1 and Q2 is on or both are off, buzzer BUZ1 is off. When buzzer BUZ1 is on and off at a certain frequency, it will produce a buzzing sound.

[0076] The circuit described above can drive two LEDs and a buzzer using only two I / O ports, IO1 and IO2. IO1 and IO2 can generate four different signal combinations as shown in Table 1.

[0077] Table 1

[0078]

[0079]

[0080] When the first LED D1 needs to be lit, the chip outputs combination 1 (IO1 outputs a high level, IO2 outputs a low level).

[0081] When the second LED D2 needs to be lit, the chip outputs combination 2 (IO1 outputs low level, IO2 outputs high level).

[0082] When it is necessary for the first LED D1 and the second LED D2 to light up simultaneously, the chip alternately outputs combination 1 and combination 2 at a certain frequency. This frequency is higher than the frequency at which the human eye can perceive light signals. Due to the persistence of vision, the human eye perceives D1 and D2 as constantly lit. It should be noted that the persistence of vision is around 10Hz. To achieve the effect of the human eye seeing D1 and D2 lit up simultaneously, the chip typically alternates between outputting combination 1 and combination 2 at a frequency of around 2000Hz to achieve a better visual effect (avoiding the perception of LED flicker).

[0083] When the LED light is not needed, the chip can output combination 3 or combination 4.

[0084] When buzzer BUZ1 is needed to sound, the chip alternately outputs combination 3 and combination 4 at a certain frequency. At this time, an alternating voltage is generated across buzzer BUZ1, and buzzer BUZ1 produces a sound due to its own piezoelectric effect. It should be noted that the alternating frequency of output combination 3 and combination 4 is the operating frequency of buzzer BUZ1, which is generally 2000Hz or 4000Hz.

[0085] When the first LED D1 or the second LED D2 needs to be lit and a buzzer is sounded, the chip alternately outputs combination 1 and combination 3 or combination 2 and combination 3 at a certain frequency. Due to the persistence of vision, the human eye perceives D1 or D2 as constantly lit. Simultaneously, an alternating voltage is generated across buzzer BUZ1, causing it to sound due to its piezoelectric effect. It should be noted that the alternating frequency of outputting combination 1 and combination 3 or combination 2 and combination 3 needs to be higher than the persistence of vision frequency (around 10Hz) to achieve the effect of D1 or D2 being lit. Additionally, it must meet the operating frequency of buzzer BUZ1, typically set to 2000Hz or 4000Hz.

[0086] When it is necessary for the first LED D1 and the second LED D2 to light up simultaneously and for a buzzer to sound, the chip alternately outputs combination 1, combination 2, and combination 3 at a certain frequency. Due to the persistence of vision, the human eye perceives D1 and D2 as constantly lit, while an alternating voltage is generated across buzzer BUZ1, causing it to sound due to its piezoelectric effect. It should be noted that the alternating frequency of output combinations 1, 2, and 3 needs to be higher than the persistence of vision (around 10Hz) to achieve the effect of D1 and D2 lighting up simultaneously. Additionally, it must meet the operating frequency of buzzer BUZ1, typically set to 2000Hz or 4000Hz.

[0087] The functional multiplexing circuit provided in this embodiment solves the problem of existing technologies requiring three chip I / O ports to drive two LEDs and one buzzer, which consumes a lot of resources. This embodiment uses only two chip I / O ports to drive two LEDs and one buzzer, saving one chip I / O port and reducing costs.

[0088] This utility model also provides an electrical device, such as Figure 3 As shown, the electrical device includes a function multiplexing circuit 301 provided in another embodiment of the present invention. For details regarding the function multiplexing circuit 301, please refer to the relevant description of another embodiment of the present invention, which will not be repeated here.

[0089] For example, the electrical device may be a product such as a fan, electric heater, or humidifier that requires both a dual LED display and a buzzer.

[0090] The electrical device provided in this embodiment of the utility model uses a function multiplexing circuit to control the LED light control circuit and the buzzer control circuit using two level signals. Each level signal can independently control one LED light to turn on or off. The two level signals alternately output high and low level signals, at which time an alternating voltage is generated at the two ends of the buzzer. The buzzer produces a buzzing sound due to its own piezoelectric effect. Thus, by using two level signals, the functions of two LED lights and one buzzer are multiplexed, which improves the user experience. Furthermore, since the two level signals only need to occupy two IO resources, one IO port resource can be saved, reducing the requirements for the selection of IO port resources of the external control chip, reducing the chip selection cost, and thus reducing the hardware cost of the entire electrical device product.

[0091] Although embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A function multiplexing circuit, characterized by comprising: include: LED light control circuit and buzzer control circuit, among which... The LED lamp control circuit includes a first LED lamp and a second LED lamp. The first LED lamp and the second LED lamp are connected in reverse parallel connection. One end of the first LED lamp is connected to a first level signal and the other end is connected to a second level signal. The buzzer control circuit includes: a buzzer, a first control circuit, and a second control circuit. The control terminal of the first control circuit is externally connected to the second level signal, the first terminal is grounded, and the second terminal is connected to the first terminal of the buzzer. The control terminal of the second control circuit is externally connected to the first level signal, the first terminal is externally connected to a power supply, and the second terminal is connected to the second terminal of the buzzer.

2. The functional multiplexing circuit of claim 1, wherein, Also includes: The controller has its first output port connected to one end of the first LED and the control terminal of the second control circuit, respectively, for outputting the first level signal. The second output port of the controller is connected to the other end of the first LED and the control terminal of the first control circuit, respectively, and is used to output the second level signal.

3. The functional multiplexing circuit of claim 1, wherein, The first control circuit includes: a first controlled switch, wherein the control terminal of the first controlled switch is externally connected to the second level signal, the first terminal is grounded, and the second terminal is connected to the first terminal of the buzzer; The first controlled switch is turned on when the second level signal is high. The first controlled switch is turned off when the second level signal is low.

4. The functional multiplexing circuit of claim 3, wherein, The first control circuit further includes: a first resistor and a second resistor, wherein, One end of the first resistor is externally connected to the second level signal, and the other end is connected to one end of the second resistor and the control terminal of the first controlled switch, respectively. The other end of the second resistor is connected to the first end of the first controlled switch.

5. The functional multiplexing circuit of claim 1, wherein, The second control circuit includes: a second controlled switch and a third controlled switch, wherein the control terminal of the second controlled switch is externally connected to the first level signal, the first terminal is grounded, the second terminal is connected to the control terminal of the third controlled switch, the first terminal of the third controlled switch is connected to the second terminal of the buzzer, and the second terminal is externally connected to the power supply; When the first level signal is high, the second controlled switch is turned on, and the third controlled switch is turned on; When the first level signal is low, the second controlled switch is turned off, and the third controlled switch is also turned off.

6. The functional multiplexing circuit of claim 5, wherein, The second control circuit further includes: a third resistor, a fourth resistor, a fifth resistor, and a sixth resistor, wherein, One end of the third resistor is connected to the first level signal, and the other end is connected to one end of the fourth resistor and the control terminal of the second controlled switch, respectively. The other end of the fourth resistor is connected to the first end of the second controlled switch; One end of the fifth resistor is connected to the second end of the second controlled switch, and the other end is connected to the control end of the third controlled switch and one end of the sixth resistor, respectively. The other end of the sixth resistor is connected to the power supply.

7. The functional multiplexing circuit of claim 1, wherein, The LED control circuit further includes a seventh resistor, one end of which is connected to the first level signal, and the other end is connected to the positive terminal of the first LED.

8. The functional multiplexing circuit of claim 3, wherein, The first controlled switch is an NPN transistor.

9. The functional multiplexing circuit of claim 5, wherein, The second controlled switch is an NPN transistor and the third controlled switch is a PNP transistor.

10. An electrical appliance characterized by The electrical appliance comprises a function multiplexing circuit as claimed in any of the claims 1-9.

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