A single double line conversion half duplex serial communication circuit

Abstract

This utility model relates to a half-duplex serial communication circuit with single-to-double-wire conversion, including an interface module, a first operational amplifier module, a second operational amplifier module, a power supply filter module connected to the power supply pins of the first and second operational amplifier modules; a resistor network module connected to the input and output pins of the first and second operational amplifier modules; and a power supply control module connected to the interface module, the first operational amplifier module, and the second operational amplifier module. The first and second operational amplifier modules have clearly defined functions, respectively amplifying the signals on the transmitting and receiving paths to ensure that the signal strength meets the transmission requirements. This enables flexible switching between transmitting and receiving in half-duplex communication. The coordinated operation of each module significantly improves the circuit's signal processing capability and anti-interference performance, ensuring the stability and reliability of serial communication in single-to-double-wire conversion scenarios.

Description

Technical Field

[0001] This utility model relates to the field of communication circuits, and in particular to a half-duplex serial communication circuit that converts between single and double wires. Background Technology

[0002] In scenarios such as industrial control, intelligent sensing, and device-level data interaction, half-duplex serial communication plays an important role in applications with limited wiring space and strict cost control because it can achieve bidirectional data interaction with only one or two transmission lines. Its core requirement is to achieve reliable single-to-double-line transmission mode switching and stable signal interaction.

[0003] Existing half-duplex serial communication circuits suffer from a critical problem of insufficient module coordination in implementing the core functions of single-to-double-line conversion and half-duplex transmission and reception. This not only increases the switching response delay but also easily causes crosstalk between transmitted and received signals due to parameter residue. In particular, crosstalk can directly lead to an increase in the data error rate when transmitting high-frequency serial signals. Utility Model Content

[0004] The purpose of this invention is to provide a half-duplex serial communication circuit that converts between single and double wires, in order to solve the problems existing in the prior art.

[0005] The above-mentioned technical objective of this utility model is achieved through the following technical solution:

[0006] A half-duplex serial communication circuit with single-to-double-wire conversion, comprising:

[0007] The interface module is used to receive external serial port signals and output reverse processing signals;

[0008] The first operational amplifier module is used to amplify and impedance match the serial port signal in the transmission path;

[0009] The second operational amplifier module is used to amplify and impedance match the serial port signal of the receiving path. The interface module is electrically connected to the first operational amplifier module and the second operational amplifier module respectively.

[0010] A power supply filtering module is used to filter the operating power supply of the first operational amplifier module and the second operational amplifier module. The power supply filtering module is connected to the power supply pins of the first operational amplifier module and the second operational amplifier module.

[0011] A resistor network module is provided, which is connected to the input and output pins of the first operational amplifier module and the second operational amplifier module. The resistor network module is used to realize signal feedback and input and output impedance matching.

[0012] The power supply control module is used to provide DC operating power and enable control signals for half-duplex transmit / receive switching. The power supply control module is connected to the interface module, the first operational amplifier module, and the second operational amplifier module.

[0013] By adopting the above technical solution, the first and second operational amplifier modules have clear division of labor, accurately amplifying the signals in the transmission and reception paths respectively to ensure that the signal strength meets the transmission requirements; the power supply filtering module adopts a combination design of electrolytic capacitors and ceramic capacitors to effectively filter out high and low frequency noise in the power supply and provide a clean operating voltage for the amplifier module; the power supply control module not only provides stable positive and negative DC power, but also realizes flexible switching between half-duplex communication transmission and reception through enable control. The cooperation of each module significantly improves the signal processing capability and anti-interference performance of the circuit, ensuring the stability and reliability of serial communication in single-line / double-line conversion scenarios.

[0014] In a further embodiment, the interface module includes a connector with pins 1 to 10; the other end of pin 2 of the connector is connected to an external serial port input signal, the other end of pin 5 of the connector leads out an inverted processing signal, the other end of pin 1 of the connector is connected to the enable control terminal of the power supply control module, the other ends of pins 4, 8, and 10 of the connector are connected to digital ground, the other end of pin 3 of the connector is connected to the positive power output terminal of the power supply control module, and the other ends of pins 6, 7, and 9 of the connector are connected to digital ground.

[0015] In a further embodiment, the first operational amplifier module includes a first amplifier. The other ends of pins 21 and 28 of the first amplifier are left floating. The other end of pin 22 of the first amplifier is connected to one end of feedback resistor R791 and one end of feedback resistor R792 in the resistor network module, respectively. The other end of pin 23 of the first amplifier is connected to the other end of input matching resistor R793 in the resistor network module. The other end of pin 24 of the first amplifier is connected to the negative power supply output terminal of the power supply control module. The other end of pin 25 of the first amplifier is left floating. The other end of pin 26 of the first amplifier is connected to the other ends of feedback resistor R791, feedback resistor R792, and one end of output matching resistor R794 in the resistor network module, respectively. The other end of pin 27 of the first amplifier is connected to the positive power supply output terminal of the power supply control module.

[0016] In a further embodiment, the second operational amplifier module includes a second amplifier. The other ends of pins 11 and 18 of the second amplifier are left floating. The other end of pin 12 of the second amplifier is connected to one end of feedback resistor R805 and one end of feedback resistor R808 in the resistor network module, respectively. The other end of pin 13 of the second amplifier is connected to the other end of input matching resistor R809 in the resistor network module. The other end of pin 14 of the second amplifier is connected to the negative power supply output terminal of the power supply control module. The other end of pin 15 of the second amplifier is left floating. The other end of pin 16 of the second amplifier is connected to the other ends of feedback resistor R805, feedback resistor R808, and one end of output matching resistor R810 in the resistor network module, respectively. The other end of pin 17 of the second amplifier is connected to the positive power supply output terminal of the power supply control module.

[0017] In a further embodiment, the power supply filtering module includes a first positive power supply filter group, a first negative power supply filter group, a second positive power supply filter group, and a second negative power supply filter group; the first positive power supply filter group includes an electrolytic capacitor C123, a ceramic capacitor C126, and a ceramic capacitor C127. One end of the electrolytic capacitor C123 is connected to pin 27 of the first amplifier, and the other end of the electrolytic capacitor C123 is connected to digital ground. One end of the ceramic capacitor C126 is connected to pin 27 of the first amplifier, and the other end of the ceramic capacitor C126 is connected to digital ground. One end of the ceramic capacitor C127 is connected to the first amplifier. Pin 27 of the first amplifier is connected to the digital ground at one end of the ceramic capacitor C127. The first negative power supply filter group includes an electrolytic capacitor C128, a ceramic capacitor C124, and a ceramic capacitor C125. One end of the electrolytic capacitor C128 is connected to pin 24 of the first amplifier, and the other end of the ceramic capacitor C124 is connected to the digital ground at one end of the first amplifier. The other end of the ceramic capacitor C125 is connected to pin 24 of the first amplifier, and the other end of the ceramic capacitor C125 is connected to the digital ground at one end of the first amplifier.

[0018] In a further embodiment, the second positive power supply filter group includes an electrolytic capacitor C136, a ceramic capacitor C137, and a ceramic capacitor C138. One end of the electrolytic capacitor C136 is connected to pin 17 of the second amplifier, and the other end of the electrolytic capacitor C136 is connected to digital ground. One end of the ceramic capacitor C137 is connected to pin 17 of the second amplifier, and the other end of the ceramic capacitor C137 is connected to digital ground. One end of the ceramic capacitor C138 is connected to pin 17 of the second amplifier, and the other end of the ceramic capacitor C138 is connected to... The second negative power supply filter group includes an electrolytic capacitor C139, a ceramic capacitor C140, and a ceramic capacitor C141. One end of the electrolytic capacitor C139 is connected to pin 14 of the second amplifier, and the other end of the electrolytic capacitor C139 is connected to digital ground. One end of the ceramic capacitor C140 is connected to pin 14 of the second amplifier, and the other end of the ceramic capacitor C141 is connected to digital ground.

[0019] In a further embodiment, the resistor network module includes a feedback resistor, an input matching resistor, and an output matching resistor; the feedback resistor includes R791, R792, R805, and R808. One end of feedback resistor R791 is connected to pin 22 of the first amplifier, and the other end of feedback resistor R791 is connected to pin 26 of the first amplifier. One end of feedback resistor R792 is connected to pin 22 of the first amplifier, and the other end of feedback resistor R792 is connected to pin 26 of the first amplifier. One end of feedback resistor R805 is connected to pin 12 of the second amplifier. One end of the first amplifier is connected to pin 16 of the second amplifier. The other end of the feedback resistor R808 is connected to pin 12 of the second amplifier. The other end of the feedback resistor R808 is connected to pin 16 of the second amplifier. The input matching resistors include R793 and R809. One end of the input matching resistor R793 is connected to pin 2 of the connector in the interface module. The other end of the input matching resistor R793 is connected to pin 23 of the first amplifier. One end of the input matching resistor R809 is connected to pin 2 of the connector in the interface module. The other end of the input matching resistor R809 is connected to pin 13 of the second amplifier.

[0020] In a further embodiment, the output matching resistors include R794, R795, R810, and R811. One end of the output matching resistor R794 is connected to pin 26 of the first amplifier, the other end of the output matching resistor R794 is connected to one end of the output matching resistor R795, the other end of the output matching resistor R795 is connected to the transmitting node, one end of the output matching resistor R810 is connected to pin 16 of the second amplifier, the other end of the output matching resistor R810 is connected to one end of the output matching resistor R811, and the other end of the output matching resistor R811 is connected to the receiving node. The other end of the positive power output terminal of the power supply control module is connected to pin 27 of the first amplifier and pin 17 of the second amplifier, the other end of the negative power output terminal of the power supply control module is connected to pin 24 of the first amplifier and pin 14 of the second amplifier, and the other end of the enable control terminal of the power supply control module is connected to pin 1 of the connector in the interface module.

[0021] In summary, this utility model has the following beneficial effects:

[0022] 1. The power supply control module not only provides a stable positive and negative DC power supply, but also enables flexible switching between half-duplex communication transmission and reception through enable control. The coordinated operation of each module significantly improves the circuit's signal processing capability and anti-interference performance, ensuring the stability and reliability of serial communication in single-to-double-wire switching scenarios. Attached Figure Description

[0023] Figure 1 This is the overall circuit diagram of this utility model;

[0024] Figure 2 This is the circuit diagram of the first operational amplifier module of this utility model;

[0025] Figure 3 This is the circuit diagram of the second operational amplifier module of this utility model. Detailed Implementation

[0026] The present invention will be further described in detail below with reference to the accompanying drawings.

[0027] Identical parts are indicated by the same reference numerals. It should be noted that the terms "front," "rear," "left," "right," "upper," and "lower" used in the following description refer to the attached figures. Figure 1In this specification, the terms "bottom surface" and "top surface," "inner" and "outer" refer to the direction toward or away from the geometry of a specific component. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this specification, "a plurality of" means two or more, unless otherwise explicitly and specifically defined by the direction of the center.

[0028] Example 1:

[0029] like Figures 1-3 As shown, a half-duplex serial communication circuit with single-to-double-wire conversion includes an interface module for receiving external serial port signals and outputting inverted processing signals; a first operational amplifier module for amplifying and impedance matching the serial port signals in the transmitting path; a second operational amplifier module for amplifying and impedance matching the serial port signals in the receiving path, with the interface module electrically connected to both the first and second operational amplifier modules; a power supply filter module for filtering the operating power of both modules, with the filter module connected to the power supply pins of both modules; a resistor network module connected to the input and output pins of both modules, used for signal feedback and input / output impedance matching; and a power supply control module for providing DC operating power and enabling control signals for half-duplex transmit / receive switching, with the control module connected to the interface module, the first operational amplifier module, and the second operational amplifier module.

[0030] The interface module includes a connector with pins 1 to 10. The other end of pin 2 of the connector is connected to an external serial port input signal, the other end of pin 5 of the connector leads out an inverted processing signal, the other end of pin 1 of the connector is connected to the enable control terminal of the power supply control module, the other ends of pins 4, 8, and 10 of the connector are connected to digital ground, the other end of pin 3 of the connector is connected to the positive power output terminal of the power supply control module, and the other ends of pins 6, 7, and 9 of the connector are connected to digital ground.

[0031] The first operational amplifier module includes a first amplifier. The other ends of pins 21 and 28 of the first amplifier are left floating. The other end of pin 22 of the first amplifier is connected to one end of feedback resistor R791 and one end of feedback resistor R792 in the resistor network module, respectively. The other end of pin 23 of the first amplifier is connected to the other end of input matching resistor R793 in the resistor network module. The other end of pin 24 of the first amplifier is connected to the negative power supply output terminal of the power supply control module. The other end of pin 25 of the first amplifier is left floating. The other end of pin 26 of the first amplifier is connected to the other ends of feedback resistor R791, feedback resistor R792 and one end of output matching resistor R794 in the resistor network module, respectively. The other end of pin 27 of the first amplifier is connected to the positive power supply output terminal of the power supply control module.

[0032] The second operational amplifier module includes a second amplifier. The other ends of pins 11 and 18 of the second amplifier are left floating. The other end of pin 12 of the second amplifier is connected to one end of feedback resistor R805 and one end of feedback resistor R808 in the resistor network module, respectively. The other end of pin 13 of the second amplifier is connected to the other end of input matching resistor R809 in the resistor network module. The other end of pin 14 of the second amplifier is connected to the negative power supply output terminal of the power supply control module. The other end of pin 15 of the second amplifier is left floating. The other end of pin 16 of the second amplifier is connected to the other ends of feedback resistor R805, feedback resistor R808, and one end of output matching resistor R810 in the resistor network module, respectively. The other end of pin 17 of the second amplifier is connected to the positive power supply output terminal of the power supply control module.

[0033] The power supply filtering module includes a first positive power supply filter group, a first negative power supply filter group, a second positive power supply filter group, and a second negative power supply filter group. The first positive power supply filter group includes an electrolytic capacitor C123, a ceramic capacitor C126, and a ceramic capacitor C127. One end of the electrolytic capacitor C123 is connected to pin 27 of the first amplifier, and the other end of the electrolytic capacitor C123 is connected to digital ground. One end of the ceramic capacitor C126 is connected to pin 27 of the first amplifier, and the other end of the ceramic capacitor C126 is connected to digital ground. The other end of the ceramic capacitor C127 is also connected to pin 27 of the first amplifier. The other end of ceramic capacitor C127 is connected to digital ground; the first negative power supply filter group includes electrolytic capacitor C128, ceramic capacitor C124 and ceramic capacitor C125. The other end of one end of electrolytic capacitor C128 is connected to pin 24 of the first amplifier and is connected to digital ground. The other end of one end of ceramic capacitor C124 is connected to pin 24 of the first amplifier and is connected to digital ground. The other end of one end of ceramic capacitor C125 is connected to pin 24 of the first amplifier and is connected to digital ground.

[0034] The second positive power supply filter group includes an electrolytic capacitor C136, a ceramic capacitor C137, and a ceramic capacitor C138. One end of the electrolytic capacitor C136 is connected to pin 17 of the second amplifier, and the other end of the electrolytic capacitor C136 is connected to digital ground. One end of the ceramic capacitor C137 is connected to pin 17 of the second amplifier, and the other end of the ceramic capacitor C137 is connected to digital ground. One end of the ceramic capacitor C138 is connected to pin 17 of the second amplifier, and the other end of the ceramic capacitor C138 is connected to digital ground. The second negative power supply filter group includes electrolytic capacitor C139, ceramic capacitor C140, and ceramic capacitor C141. One end of electrolytic capacitor C139 is connected to pin 14 of the second amplifier, and the other end of the other end of electrolytic capacitor C139 is connected to digital ground. One end of ceramic capacitor C140 is connected to pin 14 of the second amplifier, and the other end of the other end of ceramic capacitor C140 is connected to digital ground. One end of ceramic capacitor C141 is connected to pin 14 of the second amplifier, and the other end of the other end of ceramic capacitor C141 is connected to digital ground.

[0035] The resistor network module includes a feedback resistor, an input matching resistor, and an output matching resistor. The feedback resistors include R791, R792, R805, and R808. One end of feedback resistor R791 is connected to pin 22 of the first amplifier, and the other end of feedback resistor R791 is connected to pin 26 of the first amplifier. One end of feedback resistor R792 is connected to pin 22 of the first amplifier, and the other end of feedback resistor R805 is connected to pin 12 of the second amplifier. The second amplifier is connected to pin 16. One end of the feedback resistor R808 is connected to pin 12 of the second amplifier, and the other end of the feedback resistor R808 is connected to pin 16 of the second amplifier. The input matching resistors include R793 and R809. One end of the input matching resistor R793 is connected to pin 2 of the connector in the interface module, and the other end of the input matching resistor R793 is connected to pin 23 of the first amplifier. One end of the input matching resistor R809 is connected to pin 2 of the connector in the interface module, and the other end of the input matching resistor R809 is connected to pin 13 of the second amplifier.

[0036] The output matching resistors include R794, R795, R810, and R811. One end of the output matching resistor R794 is connected to pin 26 of the first amplifier. The other end of the output matching resistor R794 is connected to one end of the output matching resistor R795. The other end of the output matching resistor R795 is connected to the transmitting node. One end of the output matching resistor R810 is connected to pin 16 of the second amplifier. The other end of the output matching resistor R810 is connected to one end of the output matching resistor R811. The other end of the output matching resistor R811 is connected to the receiving node. The other end of the positive power output terminal of the power supply control module is connected to pin 27 of the first amplifier and pin 17 of the second amplifier, respectively. The other end of the negative power output terminal of the power supply control module is connected to pin 24 of the first amplifier and pin 14 of the second amplifier, respectively. The other end of the enable control terminal of the power supply control module is connected to pin 1 of the connector in the interface module.

[0037] Specific implementation process: When the circuit is in transmit mode, the power supply control module outputs a control signal through enable control terminal connector pin 1 to activate the first operational amplifier module and shut down the second operational amplifier module. External serial port signals are input through connector pin 2 of the interface module and transmitted to the non-inverting input pin 23 of the first amplifier via the input matching resistor R793 of the resistor network module. Powered by positive and negative power supply pins 24 and 27, the first amplifier stably amplifies the signal through a negative feedback loop formed by feedback resistors R791 and R792. The amplified signal is then transmitted to the transmitting node after impedance matching via output matching resistors R794 and R795 to complete signal transmission. When the circuit switches to receive mode, the power supply control module switches the control logic through the enable control terminal, activating the second operational amplifier module and shutting down the first operational amplifier module. The external serial port signal is still input from connector pin 2 and transmitted to the non-inverting input pin 13 of the second amplifier via input matching resistor R809. The second amplifier, powered by positive and negative power supply pins 14 and 17, amplifies the signal through a negative feedback loop formed by feedback resistors R805 and R808. The amplified signal is then transmitted to the receiving node after impedance matching via output matching resistors R810 and R811 to complete signal reception. The power supply filtering module always uses a combination of electrolytic capacitors and ceramic capacitors to filter out high and low frequency noise in the power supplies of the first and second amplifiers, providing a stable power supply for signal processing. The multi-pin grounding design of the interface module continuously reduces interference, ensures the integrity of signal transmission, and realizes reliable communication switching in half-duplex mode.

[0038] In the embodiments disclosed in this utility model, the terms "installation," "connection," "linking," and "fixing" should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; "linking" can be a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments disclosed in this utility model according to the specific circumstances.

[0039] This specific embodiment is merely an explanation of the present utility model and is not intended to limit the present utility model. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but as long as they are within the scope of the claims of the present utility model, they are protected by patent law.

Claims

1. A half-duplex serial communication circuit for single-to-double-wire conversion, characterized in that, include: The interface module is used to receive external serial port signals and output reverse processing signals; The first operational amplifier module is used to amplify and impedance match the serial port signal in the transmission path; The second operational amplifier module is used to amplify and impedance match the serial port signal of the receiving path. The interface module is electrically connected to the first operational amplifier module and the second operational amplifier module respectively. A power supply filtering module is used to filter the operating power supply of the first operational amplifier module and the second operational amplifier module. The power supply filtering module is connected to the power supply pins of the first operational amplifier module and the second operational amplifier module. A resistor network module is provided, which is connected to the input and output pins of the first operational amplifier module and the second operational amplifier module. The resistor network module is used to realize signal feedback and input and output impedance matching. The power supply control module is used to provide DC operating power and enable control signals for half-duplex transmit / receive switching. The power supply control module is connected to the interface module, the first operational amplifier module, and the second operational amplifier module.

2. The half-duplex serial communication circuit with single-to-double-wire conversion according to claim 1, characterized in that: The interface module includes a connector with pins 1 to 10. The other end of pin 2 of the connector is connected to an external serial port input signal, the other end of pin 5 of the connector leads out an inverted processing signal, the other end of pin 1 of the connector is connected to the enable control terminal of the power supply control module, the other ends of pins 4, 8, and 10 of the connector are connected to digital ground, the other end of pin 3 of the connector is connected to the positive power output terminal of the power supply control module, and the other ends of pins 6, 7, and 9 of the connector are connected to digital ground.

3. The half-duplex serial communication circuit with single-to-double-wire conversion according to claim 2, characterized in that: The first operational amplifier module includes a first amplifier. The other ends of pins 21 and 28 of the first amplifier are left floating. The other end of pin 22 of the first amplifier is connected to one end of feedback resistor R791 and one end of feedback resistor R792 in the resistor network module, respectively. The other end of pin 23 of the first amplifier is connected to the other end of input matching resistor R793 in the resistor network module. The other end of pin 24 of the first amplifier is connected to the negative power supply output terminal of the power supply control module. The other end of pin 25 of the first amplifier is left floating. The other end of pin 26 of the first amplifier is connected to the other ends of feedback resistor R791, feedback resistor R792 and one end of output matching resistor R794 in the resistor network module, respectively. The other end of pin 27 of the first amplifier is connected to the positive power supply output terminal of the power supply control module.

4. A half-duplex serial communication circuit with single-to-double-wire conversion according to claim 2, characterized in that: The second operational amplifier module includes a second amplifier. The other ends of pins 11 and 18 of the second amplifier are left floating. The other end of pin 12 of the second amplifier is connected to one end of feedback resistor R805 and one end of feedback resistor R808 in the resistor network module, respectively. The other end of pin 13 of the second amplifier is connected to the other end of input matching resistor R809 in the resistor network module. The other end of pin 14 of the second amplifier is connected to the negative power supply output terminal of the power supply control module. The other end of pin 15 of the second amplifier is left floating. The other end of pin 16 of the second amplifier is connected to the other ends of feedback resistor R805, feedback resistor R808, and one end of output matching resistor R810 in the resistor network module, respectively. The other end of pin 17 of the second amplifier is connected to the positive power supply output terminal of the power supply control module.

5. A half-duplex serial communication circuit with single-to-double-wire conversion according to claim 3, characterized in that: The power supply filtering module includes a first positive power supply filter group, a first negative power supply filter group, a second positive power supply filter group, and a second negative power supply filter group. The first positive power supply filter group includes an electrolytic capacitor C123, a ceramic capacitor C126, and a ceramic capacitor C127. One end of the electrolytic capacitor C123 is connected to pin 27 of the first amplifier, and the other end of the electrolytic capacitor C123 is connected to digital ground. One end of the ceramic capacitor C126 is connected to pin 27 of the first amplifier, and the other end of the ceramic capacitor C126 is connected to digital ground. The other end of the ceramic capacitor C127 is connected to pin 27 of the first amplifier. The other end of the ceramic capacitor C127 is connected to digital ground; the first negative power supply filter group includes an electrolytic capacitor C128, a ceramic capacitor C124, and a ceramic capacitor C125. The other end of one end of the electrolytic capacitor C128 is connected to pin 24 of the first amplifier, and the other end of the ceramic capacitor C124 is connected to pin 24 of the first amplifier, and the other end of the ceramic capacitor C125 is connected to pin 24 of the first amplifier, and the other end of the ceramic capacitor C125 is connected to digital ground.

6. A half-duplex serial communication circuit with single-to-double-wire conversion according to claim 5, characterized in that: The second positive power supply filter group includes an electrolytic capacitor C136, a ceramic capacitor C137, and a ceramic capacitor C138. One end of the electrolytic capacitor C136 is connected to pin 17 of the second amplifier, and the other end of the electrolytic capacitor C136 is connected to digital ground. One end of the ceramic capacitor C137 is connected to pin 17 of the second amplifier, and the other end of the ceramic capacitor C137 is connected to digital ground. One end of the ceramic capacitor C138 is connected to pin 17 of the second amplifier, and the other end of the ceramic capacitor C138 is connected to digital ground. The second negative power supply filter group includes an electrolytic capacitor C139, a ceramic capacitor C140, and a ceramic capacitor C141. One end of the electrolytic capacitor C139 is connected to pin 14 of the second amplifier, and the other end of the electrolytic capacitor C139 is connected to digital ground. One end of the ceramic capacitor C140 is connected to pin 14 of the second amplifier, and the other end of the ceramic capacitor C140 is connected to digital ground. One end of the ceramic capacitor C141 is connected to pin 14 of the second amplifier, and the other end of the ceramic capacitor C141 is connected to digital ground.

7. A half-duplex serial communication circuit with single-to-double-wire conversion according to claim 3, characterized in that: The resistor network module includes a feedback resistor, an input matching resistor, and an output matching resistor. The feedback resistors include R791, R792, R805, and R808. One end of feedback resistor R791 is connected to pin 22 of the first amplifier, and the other end of feedback resistor R791 is connected to pin 26 of the first amplifier. One end of feedback resistor R792 is connected to pin 22 of the first amplifier, and the other end of feedback resistor R792 is connected to pin 26 of the first amplifier. One end of feedback resistor R805 is connected to pin 12 of the second amplifier. The second amplifier is connected to pin 16. One end of the feedback resistor R808 is connected to pin 12 of the second amplifier, and the other end of the feedback resistor R808 is connected to pin 16 of the second amplifier. The input matching resistors include R793 and R809. One end of the input matching resistor R793 is connected to pin 2 of the connector in the interface module, and the other end of the input matching resistor R793 is connected to pin 23 of the first amplifier. One end of the input matching resistor R809 is connected to pin 2 of the connector in the interface module, and the other end of the input matching resistor R809 is connected to pin 13 of the second amplifier.

8. A half-duplex serial communication circuit with single-to-double-wire conversion according to claim 3, characterized in that: The output matching resistors include R794, R795, R810, and R811. One end of output matching resistor R794 is connected to pin 26 of the first amplifier. The other end of output matching resistor R794 is connected to one end of output matching resistor R795. The other end of output matching resistor R795 is connected to the transmitting node. One end of output matching resistor R810 is connected to pin 16 of the second amplifier. The other end of output matching resistor R810 is connected to one end of output matching resistor R811. The other end of output matching resistor R811 is connected to the receiving node. The other end of the positive power output terminal of the power supply control module is connected to pin 27 of the first amplifier and pin 17 of the second amplifier. The other end of the negative power output terminal of the power supply control module is connected to pin 24 of the first amplifier and pin 14 of the second amplifier. The other end of the enable control terminal of the power supply control module is connected to pin 1 of the connector in the interface module.

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