Serial port multiplexing circuit

Abstract

The utility model discloses a serial port multiplexing circuit, which relates to the technical field of electronic circuits, and comprises a plurality of communication modules connected with a battery microcontroller, and any communication module comprises a power supply enabling circuit, a communication conversion circuit and a communication identification circuit which are adaptively connected, the communication conversion circuit is connected with a serial port of the battery microcontroller; for any communication module, the communication identification circuit is used for generating a communication identification signal when the communication conversion circuit is connected with external equipment, the battery microcontroller is used for generating a communication enable signal according to the communication identification signal, and the communication enable signal is used for controlling the power supply enable circuit to supply power to the communication conversion circuit. And the battery is communicated with external equipment through the communication conversion circuit. According to the serial port multiplexing circuit, serial ports of the microcontroller can be saved, and occupation of serial port resources of the microcontroller is reduced.

Description

Technical Field

[0001] This utility model relates to the field of electronic circuit technology, and in particular to a serial port multiplexing circuit. Background Technology

[0002] Shared batteries typically use RS-485 communication in battery swapping cabinets, but when used on electric two-wheelers, they may use serial communication methods such as single-wire communication. To accommodate multiple communication methods, the BMS MCU in a shared battery usually uses multiple UART function ports. However, this method occupies multiple UART function ports, resulting in wasted MCU resources. Utility Model Content

[0003] In response to the aforementioned problems and technical requirements, the applicant has proposed a serial port multiplexing circuit.

[0004] The technical solution of this utility model is as follows:

[0005] A serial port multiplexing circuit includes multiple communication modules connected to a battery microcontroller. Each of the communication modules includes a power enable circuit, a communication conversion circuit, and a communication identification circuit. The communication conversion circuit is connected to the serial port of the power enable circuit, the communication identification circuit, and the battery microcontroller. The power enable circuit and the communication identification circuit are both connected to the battery microcontroller.

[0006] For any communication module, the communication identification circuit is used to generate a communication identification signal when the communication conversion circuit is connected to an external device, and the battery microcontroller is used to generate a communication enable signal based on the communication identification signal. The communication enable signal is used to control the power enable circuit to supply power to the communication conversion circuit so that the battery can communicate with the external device through the communication conversion circuit.

[0007] A further technical solution is that only one communication conversion circuit within the communication module is connected to the external device at any given time.

[0008] The further technical solution is that the power enable circuit includes a switching transistor Q1, a switching transistor Q2, and a resistor R1, and the serial port of the battery microcontroller includes a UART function port.

[0009] The third electrode of the switching transistor Q1 is connected to the power supply VCC. The second electrode of the switching transistor Q1 is connected to the third electrode of the switching transistor Q2 through a resistor R1. The second electrode of the switching transistor Q2 is connected to the battery microcontroller to receive the communication enable signal. The first electrode of the switching transistor Q2 is grounded.

[0010] A further technical solution is that the communication identification circuit includes an optocoupler U3 and a resistor R3;

[0011] The primary-side light-emitting diode of the optocoupler U3 is connected to the communication conversion circuit, the collector of the phototransistor of the optocoupler U3 is connected to the battery microcontroller, and the emitter of the phototransistor of the optocoupler U3 is grounded.

[0012] A further technical solution is that the communication conversion circuit includes a single-wire communication conversion circuit; the power enable circuit also includes diode D2a, diode D2b, and resistor R2a.

[0013] The single-wire communication conversion circuit includes resistors R7, R8, R9, R10, R11, R12, R14, R15, and R16, switching transistors T1, T2, T3, and T4, and diodes D1, D2, and D3.

[0014] The positive terminal of diode D2 is connected to the positive terminal of the light-emitting diode of optocoupler U3 through resistor R3. The positive terminal of diode D2 is also connected to the third electrode of switch T3. The first electrode of switch T3 is connected to the negative terminal of the light-emitting diode of optocoupler U3.

[0015] The second electrode of the switching transistor T3 is connected to one end of resistor R14 and resistor R16, and the other end of resistor R16 is connected to the first electrode of the switching transistor T3.

[0016] The negative terminal of diode D2 is connected to the second electrode of switch transistor T4 through resistor R11. The second electrode of switch transistor T4 is connected to the first electrode of switch transistor T4 through resistor R12. The first electrode of switch transistor T4 is connected to the negative terminal of the light-emitting diode of optocoupler U3. The third electrode of switch transistor T4 is connected to the negative terminal of diode D1.

[0017] A further technical solution is as follows: the positive terminal of diode D1 is connected to the second electrode of switching transistor T1 through resistor R10; the second electrode of switching transistor T1 is connected to the first electrode of switching transistor T1 through resistor R8; the first electrode of switching transistor T1 is connected to the first electrode of switching transistor Q1; the third electrode of switching transistor T1 is grounded through resistor R9; and the third electrode of switching transistor T1 is connected to the positive terminal of diode D2a through resistor R7; the negative terminal of diode D2a is connected to the UART function port.

[0018] The other end of resistor R14 is connected to the negative terminal of diode D3. The positive terminal of diode D3 is connected to the third electrode of switch transistor T2. The first electrode of switch transistor T2 is connected to the first electrode of switch transistor Q1. The first electrode of switch transistor T2 is connected to the second electrode of switch transistor T2 through resistor R2a. The second electrode of switch transistor T2 is connected to the positive terminal of diode D2a through resistor R15. The negative terminal of diode D2b is connected to the UART function port.

[0019] The further technical solution is that the switching transistors T1 and T2 are PNP transistors, and the switching transistors T3 and T4 are NPN transistors.

[0020] A further technical solution is that the switching transistor Q1 is a PMOS transistor and the switching transistor Q2 is an NMOS transistor.

[0021] A further technical solution is that the communication conversion circuit includes a 485 communication conversion circuit; the power enable circuit also includes diode D1a, diode D1b and resistor R1a; the 485 communication conversion circuit includes a communication isolation chip U1, the communication isolation chip U1 model includes CA-IS3721HS, and the communication isolation chip U1 includes VDD1 pin, VIA pin, VOA pin, GND1 pin, VDD2 pin, VOB pin, VIB pin, and GND2 pin;

[0022] The negative terminals of diodes D1a and D1b are connected to the UART function port of the battery microcontroller, and the positive terminal of diode D1b is connected to the first electrode of switch Q1 through resistor R1a.

[0023] The first electrode of the switching transistor Q1 is connected to the VDD1 pin, the anode of the diode D1a is connected to the VOA pin, the anode of the diode D1b is connected to the VIA pin, the VDD2 pin is connected to the power supply ISO_VCC, and the GND2 pin is grounded to the ISO_GND potential.

[0024] The further technical solution is that the 485 communication conversion circuit includes a 485 communication conversion chip U2, resistors R4, R5 and R6, the model of the 485 communication conversion chip U2 includes TP8485E, and the 485 communication conversion chip U3 includes VCC pin, A pin, B pin, GND pin, RO pin and DI pin.

[0025] Pin A is connected to the positive terminal of the LED of optocoupler U3 via resistor R3, and pin B is connected to the negative terminal of the LED of optocoupler U3.

[0026] The resistor R5 is connected between pin A and pin B, the resistor R4 is connected between pin VCC and pin A, the resistor R6 is connected between pin B and pin GND, the pin VCC is connected to the power supply ISO_VCC, and the pin GND is grounded to the potential ISO_GND.

[0027] The RO pin is connected to the VIB pin of the communication isolation chip U1, and the DI pin is connected to the VOB pin of the communication isolation chip U1. The beneficial technical effects of this invention are:

[0028] This invention provides a serial port multiplexing circuit that can achieve multi-channel and multi-mode communication with external devices using only one serial port, namely the UART function port, thereby realizing serial port multiplexing, saving the special function port of the MCU, reducing the occupation of MCU serial port resources, thereby reducing the performance requirements of the MCU and reducing costs. Attached Figure Description

[0029] Figure 1 This is a structural block diagram of one embodiment of the serial port multiplexing circuit provided by this utility model.

[0030] Figure 2 This is a circuit schematic diagram of one embodiment of the enable section of the enable power supply circuit.

[0031] Figure 3 This is a circuit diagram of one embodiment of the communication identification circuit provided by this utility model.

[0032] Figure 4 This is a circuit diagram of one embodiment of the 485 communication conversion circuit provided by this utility model.

[0033] Figure 5 This is a circuit diagram of one embodiment of the single-wire communication conversion circuit provided by this utility model. Detailed Implementation

[0034] The specific embodiments of this utility model will be further described below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of this disclosure.

[0035] This utility model provides a serial port multiplexing circuit, such as Figure 1 As shown, the device includes multiple communication modules connected to a battery microcontroller. Each of the communication modules includes a power enable circuit, a communication conversion circuit, and a communication identification circuit that are adapted and connected. The communication conversion circuit is connected to the serial port of the power enable circuit, the communication identification circuit, and the battery microcontroller. The power enable circuit and the communication identification circuit are both connected to the battery microcontroller.

[0036] For any communication module, the communication identification circuit is used to generate a communication identification signal when the communication conversion circuit is connected to an external device, and the battery microcontroller is used to generate a communication enable signal based on the communication identification signal. The communication enable signal is used to control the power enable circuit to supply power to the communication conversion circuit so that the battery can communicate with the external device through the communication conversion circuit.

[0037] Specifically, in any communication module, the power enable circuit is connected to the communication conversion circuit, the communication conversion circuit is connected to the communication identification circuit, and the power enable circuit, communication conversion circuit, and communication identification circuit are all connected to the battery microcontroller (MCU). In this embodiment of the invention, the serial port specifically refers to the UART function port, and the communication conversion circuit is connected to the UART function port of the battery microcontroller. The battery microcontroller specifically refers to the microcontroller in the battery management system (BMS).

[0038] The battery microcontroller connects to multiple communication modules. When the communication conversion circuit in one of these modules connects to an external device, the communication identification circuit in that module generates a communication identification signal. The battery microcontroller then outputs a communication enable signal to the power enable circuit in that module based on the identification signal. This power enable circuit enables the communication conversion circuit, allowing the battery to communicate with the external device through the communication conversion circuit in that module. It's important to note that only one communication conversion circuit within a single communication module can communicate with the external device at any given time. In other words, the battery microcontroller uses one UART port to communicate with the external device through the communication conversion circuit in one of the communication modules simultaneously. By utilizing the serial port multiplexing circuit provided by this invention, when multiple serial communication methods are not simultaneously accessed by the MCU, only one UART port of the MCU is needed to achieve the communication function, effectively saving the MCU's serial port resources.

[0039] The number of communication modules can be set according to the actual needs of serial port multiplexing. The communication conversion circuits in multiple communication modules can use the same or different communication methods. The communication method used by the communication conversion circuit can be determined according to the communication method of the external device, which may include serial communication methods such as RS-485 communication, single-wire communication, and CAN communication. The external devices include, but are not limited to, charging cabinets and electric two-wheeled vehicles. The specific forms of the power enable circuit, communication conversion circuit, and communication identification circuit can be referred to the following description.

[0040] In one embodiment of this utility model, the power enable circuit includes a switching transistor Q1, a switching transistor Q2, a diode D1a, a diode D1b, a resistor R1, and a resistor R1a.

[0041] The switching transistors Q1 and Q2, along with resistor R1, form the enable section of the power enable circuit. In this embodiment, switching transistor Q1 is a PMOS transistor, and switching transistor Q2 is an NMOS transistor. For both NMOS and PMOS transistors, the first electrode is the source, the second electrode is the gate, and the third electrode is the drain. The third electrode of switching transistor Q1 is connected to the power supply VCC. The second electrode of switching transistor Q1 is connected to the third electrode of switching transistor Q2 through resistor R1. The second electrode of switching transistor Q2 is connected to the battery microcontroller to receive the communication enable signal. The first electrode of switching transistor Q2 is grounded. The cathodes of diodes D1a and D1b are connected to the UART port of the battery microcontroller, and the anode of diode D1b is connected to the first electrode of switching transistor Q1 through resistor R1a.

[0042] Specifically, the UART function port of the battery microcontroller includes an MCU_RXD pin for receiving data and an MCU_TXD pin for transmitting data. The cathode of diode D1a is connected to the MCU_RXD pin, and the cathode of diode D1b is connected to the MCU_TXD pin. The anode of diode D1a is connected to the data transmitting end of the communication conversion circuit, and the anode of diode D1b is connected to the data receiving end of the communication conversion circuit.

[0043] When an external device connects to a communication conversion module, causing the battery-powered MCU to generate a communication enable signal (EN), this signal is applied to the gate of switch Q2, turning on Q2 and consequently turning on switch Q1. Power supply VCC, after passing through switch Q1, generates power supply VCC1. VCC1 is applied to one end of resistor R1a, which acts as a pull-up resistor, pulling the data receiving end of the communication conversion circuit to a high level. Simultaneously, VCC1 provides power to the corresponding communication conversion circuit, enabling the power-powered MCU to communicate with the external device. At this time, since the power supply to other communication modules is not enabled, both the data receiving and transmitting ends of their communication conversion circuits are at a low level. Utilizing the unidirectional conduction of diodes, other unenabled communication modules will not affect the MCU's UART function port.

[0044] Furthermore, all communication identification circuits in the serial port multiplexing circuit have the same structure. Taking a certain communication identification circuit as an example, the communication identification circuit includes an optocoupler U3 and a resistor R3; the primary side light-emitting diode of the optocoupler U3 is connected to the communication conversion circuit, the collector of the phototransistor of the optocoupler U3 is connected to the battery microcontroller, and the emitter of the phototransistor of the optocoupler U3 is grounded.

[0045] Specifically, resistor R3 is a current-limiting resistor. The value of resistor R3 can be selected according to actual needs, ensuring that the communication identification circuit works normally without affecting the operation of the connected communication conversion circuit. When the communication identification circuit is connected to an external device, the primary-side LED of optocoupler U3 is lit, and the secondary-side phototransistor of optocoupler U3 is turned on, generating a low-level communication identification signal and outputting it to the battery MCU.

[0046] In another embodiment of this utility model, the communication conversion circuit is a 485 communication conversion circuit, such as... Figure 5 As shown, the 485 communication conversion circuit includes a communication isolation chip U1, a 485 communication conversion chip U2, resistors R4, R5, and R6. The communication isolation chip U1 is model CA-IS 3721HS and includes pins VDD1, VIA, VOA, GND1, VDD2, VOB, VIB, and GND2.

[0047] The first electrode of the switching transistor Q1 is connected to the VDD1 pin, the VOA pin is connected to the positive terminal of the diode D1a as a data transmitting terminal, the VIA pin is connected to the positive terminal of the diode D1b as a data receiving terminal, the VDD2 pin is connected to the isolated power supply ISO_VCC, and the GND2 pin is connected to the isolated ground potential ISO_GND.

[0048] The 485 communication conversion chip U2 includes the model TP8485E. The 485 communication conversion chip U3 includes a VCC pin, an A pin, a B pin, a GND pin, an RO pin, and a DI pin. The A pin is connected to the positive terminal of the LED of the optocoupler U3 through a resistor R3, and the B pin is connected to the negative terminal of the LED of the optocoupler U3. A resistor R5 is connected between the A pin and the B pin, a resistor R4 is connected between the VCC pin and the A pin, and a resistor R6 is connected between the B pin and the GND pin. The VCC pin is connected to the power supply ISO_VCC, and the GND pin is grounded to ISO_GND. The RO pin is connected to the VIB pin of the communication isolation chip U1, and the DI pin is connected to the VOB pin of the communication isolation chip U1. Pins A and B are also connected to external devices. When an external device using 485 communication is connected to pins A and B, the external device sends a message, generating a differential signal between pins A and B. This causes the LED of optocoupler U3 to light up, and the phototransistor on the secondary side of optocoupler U3 to conduct, generating a low-level communication identification signal and outputting it to the battery MCU. The battery MCU outputs a communication enable signal, and the power supply VCC is converted into power supply VCC1 after passing through the switching transistor Q1. Power supply VCC1 is applied to one end of resistor R1a, enabling the battery MCU to communicate with the external device via the communication conversion circuit using 485.

[0049] In another embodiment of this utility model, the communication conversion circuit can be a single-wire communication conversion circuit. The structure and working principle of the power enable circuit are the same as those in the above embodiment. However, for ease of distinction, diodes D1a, D1b, and resistor R1a in the power enable circuit of the previous embodiment are referred to as diodes D2a, D2b, and R2a, and the power generated by power supply VCC after passing through switch Q1 is referred to as power supply VCC2. The single-wire communication conversion circuit includes resistors R7, R8, R9, R10, R11, R12, R13, R14, R15, and R16, switch T1, switch T2, switch T3, switch T4, diodes D1, D2, and D3.

[0050] The positive terminal of diode D2 is connected to the positive terminal of the light-emitting diode of optocoupler U3 through resistor R3. The positive terminal of diode D2 is also connected to the third electrode of switch T3. The first electrode of switch T3 is connected to the negative terminal of the light-emitting diode of optocoupler U3.

[0051] The second electrode of the switching transistor T3 is connected to one end of resistor R14 and resistor R16, and the other end of resistor R16 is connected to the first electrode of the switching transistor T3.

[0052] The negative terminal of diode D2 is connected to the second electrode of switch transistor T4 through resistor R11. The second electrode of switch transistor T4 is connected to the first electrode of switch transistor T4 through resistor R12. The first electrode of switch transistor T4 is connected to the negative terminal of the LED of optocoupler U3. The third electrode of switch transistor T4 is connected to the negative terminal of diode D1. The negative terminals of diode D2 and the first electrode of switch transistor T3 are also connected to external devices. When an external device using single-wire communication is connected to the negative terminal of diode D2 and the first electrode of switch transistor T3, a high-level signal is applied to one end of resistor R3, thereby lighting up the LED of optocoupler U3. The phototransistor on the secondary side of optocoupler U3 conducts, generating a low-level communication identification signal and outputting it to the battery MCU. The battery MCU outputs a communication enable signal. Power supply VCC is converted to power supply VCC2 through switch transistor Q1. Power supply VCC2 is applied to one end of resistor R2a, enabling single-wire communication with external devices through the communication conversion circuit.

[0053] The positive terminal of diode D1 is connected to the second electrode of switch transistor T1 through resistor R10. The second electrode of switch transistor T1 is connected to the first electrode of switch transistor T1 through resistor R8. The first electrode of switch transistor T1 is connected to the first electrode of switch transistor Q1. The third electrode of switch transistor T1 is grounded through resistor R9. The third electrode of switch transistor T1 is connected to the positive terminal of diode D2a through resistor R7. The negative terminal of diode D2a is connected to the UART function port.

[0054] The other end of resistor R14 is connected to the negative terminal of diode D3. The positive terminal of diode D3 is connected to the third electrode of switch transistor T2. The first electrode of switch transistor T2 is connected to the first electrode of switch transistor Q1. The first electrode of switch transistor T2 is connected to the second electrode of switch transistor T2 through resistor R2a. The second electrode of switch transistor T2 is connected to the positive terminal of diode D2a through resistor R15. The negative terminal of diode D2b is connected to the UART function port.

[0055] In this embodiment, the switching transistors T1 and T2 are PNP transistors, and the switching transistors T3 and T4 are NPN transistors. For both PNP and NPN transistors, the first electrode is the emitter, the second electrode is the base, and the third electrode is the collector.

[0056] In the description of this specification, references to terms such as "an embodiment," "example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. The illustrative expressions of the above terms in this specification do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In the description of this application, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0057] Those skilled in the art should understand that the above descriptions are merely preferred embodiments of the present invention, and the present invention is not limited to the above embodiments. Any other improvements and variations directly derived or conceived by those skilled in the art without departing from the spirit and concept of the present invention should be considered to be included within the protection scope of the present invention.

Claims

1. A serial port multiplexing circuit, characterized in that, The device includes multiple communication modules connected to a battery microcontroller. Each of the communication modules includes a power enable circuit, a communication conversion circuit, and a communication identification circuit. The communication conversion circuit is connected to the serial port of the power enable circuit, the communication identification circuit, and the battery microcontroller. The power enable circuit and the communication identification circuit are both connected to the battery microcontroller. For any communication module, the communication identification circuit is used to generate a communication identification signal when the communication conversion circuit is connected to an external device, and the battery microcontroller is used to generate a communication enable signal based on the communication identification signal. The communication enable signal is used to control the power enable circuit to supply power to the communication conversion circuit so that the battery can communicate with the external device through the communication conversion circuit.

2. The serial port multiplexing circuit according to claim 1, characterized in that, Only one communication conversion circuit within a communication module can be connected to an external device at any given time.

3. The serial port multiplexing circuit according to claim 1, characterized in that, The power enable circuit includes switching transistors Q1 and Q2, and resistor R1. The serial port of the battery microcontroller includes a UART function port. The third electrode of the switching transistor Q1 is connected to the power supply VCC. The second electrode of the switching transistor Q1 is connected to the third electrode of the switching transistor Q2 through a resistor R1. The second electrode of the switching transistor Q2 is connected to the battery microcontroller to receive the communication enable signal. The first electrode of the switching transistor Q2 is grounded.

4. The serial port multiplexing circuit according to claim 3, characterized in that, The communication identification circuit includes an optocoupler U3 and a resistor R3; The primary-side light-emitting diode of the optocoupler U3 is connected to the communication conversion circuit, the collector of the phototransistor of the optocoupler U3 is connected to the battery microcontroller, and the emitter of the phototransistor of the optocoupler U3 is grounded.

5. The serial port multiplexing circuit according to claim 4, characterized in that, The communication conversion circuit includes a single-wire communication conversion circuit; the power enable circuit also includes diode D2a, diode D2b and resistor R2a. The single-wire communication conversion circuit includes resistors R7, R8, R9, R10, R11, R12, R14, R15, and R16, switching transistors T1, T2, T3, and T4, and diodes D1, D2, and D3. The positive terminal of diode D2 is connected to the positive terminal of the light-emitting diode of optocoupler U3 through resistor R3. The positive terminal of diode D2 is also connected to the third electrode of switch T3. The first electrode of switch T3 is connected to the negative terminal of the light-emitting diode of optocoupler U3. The second electrode of the switching transistor T3 is connected to one end of resistor R14 and resistor R16, and the other end of resistor R16 is connected to the first electrode of the switching transistor T3. The negative terminal of diode D2 is connected to the second electrode of switch transistor T4 through resistor R11. The second electrode of switch transistor T4 is connected to the first electrode of switch transistor T4 through resistor R12. The first electrode of switch transistor T4 is connected to the negative terminal of the light-emitting diode of optocoupler U3. The third electrode of switch transistor T4 is connected to the negative terminal of diode D1.

6. The serial port multiplexing circuit according to claim 5, characterized in that, The positive terminal of diode D1 is connected to the second electrode of switch transistor T1 through resistor R10. The second electrode of switch transistor T1 is connected to the first electrode of switch transistor T1 through resistor R8. The first electrode of switch transistor T1 is connected to the first electrode of switch transistor Q1. The third electrode of switch transistor T1 is grounded through resistor R9. The third electrode of switch transistor T1 is connected to the positive terminal of diode D2a through resistor R7. The negative terminal of diode D2a is connected to the UART function port. The other end of resistor R14 is connected to the negative terminal of diode D3. The positive terminal of diode D3 is connected to the third electrode of switch transistor T2. The first electrode of switch transistor T2 is connected to the first electrode of switch transistor Q1. The first electrode of switch transistor T2 is connected to the second electrode of switch transistor T2 through resistor R2a. The second electrode of switch transistor T2 is connected to the positive terminal of diode D2a through resistor R15. The negative terminal of diode D2b is connected to the UART function port.

7. The serial port multiplexing circuit according to claim 5, characterized in that, The switching transistors T1 and T2 are PNP transistors, and the switching transistors T3 and T4 are NPN transistors.

8. The serial port multiplexing circuit according to claim 3, characterized in that, The switching transistor Q1 is a PMOS transistor, and the switching transistor Q2 is an NMOS transistor.

9. The serial port multiplexing circuit according to claim 4, characterized in that, The communication conversion circuit includes a 485 communication conversion circuit; the power enable circuit further includes diodes D1a and D1b and resistor R1a; the 485 communication conversion circuit includes a communication isolation chip U1, the communication isolation chip U1 model includes CA-IS3721HS, and the communication isolation chip U1 includes VDD1 pin, VIA pin, VOA pin, GND1 pin, VDD2 pin, VOB pin, VIB pin, and GND2 pin; The negative terminals of diodes D1a and D1b are connected to the UART function port of the battery microcontroller, and the positive terminal of diode D1b is connected to the first electrode of switch Q1 through resistor R1a. The first electrode of the switching transistor Q1 is connected to the VDD1 pin, the anode of the diode D1a is connected to the VOA pin, the anode of the diode D1b is connected to the VIA pin, the VDD2 pin is connected to the power supply ISO_VCC, and the GND2 pin is grounded to the ISO_GND potential.

10. The serial port multiplexing circuit according to claim 9, characterized in that, The 485 communication conversion circuit includes a 485 communication conversion chip U2, resistors R4, R5, and R6. The model of the 485 communication conversion chip U2 is TP8485E. The 485 communication conversion chip U3 includes VCC pin, A pin, B pin, GND pin, RO pin, and DI pin. Pin A is connected to the positive terminal of the LED of optocoupler U3 via resistor R3, and pin B is connected to the negative terminal of the LED of optocoupler U3. The resistor R5 is connected between pin A and pin B, the resistor R4 is connected between pin VCC and pin A, the resistor R6 is connected between pin B and pin GND, the pin VCC is connected to the power supply ISO_VCC, and the pin GND is grounded to the potential ISO_GND. The RO pin is connected to the VIB pin of the communication isolation chip U1, and the DI pin is connected to the VOB pin of the communication isolation chip U1.

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