Matching control circuit and matching control method for signal transceiver

Abstract

The embodiment of the present specification provides a matching control circuit and a matching control method of a signal transceiver device, and relates to the technical field of communication circuit. The matching control circuit comprises an MCU master control unit, a signal transceiver device and a matching circuit. The MCU master control unit is connected with the signal transceiver device, and the signal transceiver device can perform signal transceiving based on an RS485 chip unit. The end of a differential signal transmission line of the RS485 chip unit is connected with the matching circuit and a terminal device. The matching circuit is used for adjusting the terminal impedance to be matched with the output impedance of the differential signal transmission line. The RS485 chip unit is connected with a current acquisition circuit used for acquiring the communication current between the RS485 chip unit and the terminal device. The MCU master control unit can output a target voltage signal to the matching circuit based on the communication current and the communication success rate information between the MCU master control unit and the terminal device, so that the matching circuit adjusts the terminal impedance based on the target voltage signal. In this way, the impedance change can be automatically adapted, and the reliability of RS485 communication is improved.

Description

Technical Field

[0001] The embodiments described in this specification relate to the field of communication circuit technology, specifically to a matching control circuit and matching control method for a signal transceiver device. Background Technology

[0002] The RS-485 bus is widely used in industrial automation, smart heating, building control and other fields due to its advantages such as supporting long-distance transmission, multi-point communication and strong anti-interference ability. Especially in heating systems, the 485 communication technology undertakes the key tasks of data acquisition and control command transmission due to its stability and wide device compatibility.

[0003] However, in actual engineering applications and long-term operation, the terminal matching method of 485 communication is relatively simple and it is difficult to adapt to the characteristic impedance changes caused by line aging, temperature changes, and the addition or removal of nodes. This can easily lead to a decrease in signal quality, an increase in bit error rate, or even communication interruption.

[0004] Therefore, there is an urgent need to provide a matching control circuit and matching control method for a signal transceiver device that can automatically adapt to impedance changes, achieve intelligent matching, and improve the reliability of RS485 communication. Summary of the Invention

[0005] In view of this, this specification provides a matching control circuit and matching control method for a signal transceiver device to automatically adapt to impedance changes, achieve intelligent matching, and improve the reliability of RS485 communication.

[0006] This specification provides a matching control circuit for a signal transceiver device, including an MCU main control unit, a signal transceiver device, and a matching circuit. The MCU main control unit is connected to the signal transceiver device, which is capable of signal transmission and reception based on an RS485 chip unit. The end of the differential signal transmission line of the RS485 chip unit in the signal transceiver device is connected to the matching circuit and a terminal device. The matching circuit is used to adjust the terminal impedance to match the output impedance of the differential signal transmission line. The RS485 chip unit is connected to a current acquisition circuit, which is used to acquire the communication current between the RS485 chip unit and the terminal device. Based on the communication current and the communication success rate information between the MCU main control unit and the terminal device, the MCU main control unit can output a target voltage signal to the matching circuit, so that the matching circuit adjusts the terminal impedance based on the target voltage signal.

[0007] In some embodiments, the differential signal transmission line includes an A-end differential signal transmission line and a B-end differential signal transmission line. The matching circuit is connected in parallel with the terminal device between the ends of the A-end differential signal transmission line and the B-end differential signal transmission line. The matching circuit includes a first PMOS transistor, a second PMOS transistor, a first resistor, a second resistor, and a third resistor. The drain of the first PMOS transistor is connected to the end of the B-end differential signal transmission line through the first resistor. The source of the first PMOS transistor is connected to the source of the second PMOS transistor. The drain of the second PMOS transistor is connected to the end of the A-end differential signal transmission line through the second resistor. The first designated P1 interface of the MCU main control unit is simultaneously connected to the gate of the first PMOS transistor, the gate of the second PMOS transistor, and one end of the third resistor through the first transmission line. The other end of the third resistor is connected between the source of the first PMOS transistor and the source of the second PMOS transistor. The MCU main control unit can transmit the target voltage signal based on the first transmission line to adjust the on-resistance of the first PMOS transistor and the second PMOS transistor.

[0008] In some embodiments, the matching control circuit further includes a two-stage RC low-pass filter circuit, which includes a fourth resistor, a fifth resistor, a first capacitor, and a second capacitor. The fourth resistor and the fifth resistor are connected in series on the first transmission line between the first designated P1 interface of the MCU main control unit and the matching circuit. One end of the first capacitor is connected between the fourth resistor and the fifth resistor, and the other end of the first capacitor is grounded. One end of the second capacitor is connected to the end of the fifth resistor closest to the matching circuit, and the other end of the second capacitor is grounded. The two-stage RC low-pass filter circuit is used to perform low-pass filtering on the 16-bit pulse broadband modulated voltage signal output from the first designated P1 interface of the MCU main control unit to obtain a 16-bit pulse broadband modulated DAC voltage signal as the target voltage signal. The target voltage signal is any value in [0, VCC], and VCC is the power supply voltage of the main control unit power input terminal of the MCU main control unit.

[0009] In some embodiments, the matching control circuit further includes an RS485 power control circuit; the RS485 power control circuit includes a third PMOS transistor, the second designated P3 interface of the MCU main control unit is connected to the gate of the third PMOS transistor through a second transmission line, the source of the third PMOS transistor is connected to the power input terminal of the main control unit, and the drain of the third PMOS transistor serves as the RS485 power supply terminal of the RS485 chip unit, which is used to supply power to the RS485 chip unit; the MCU main control unit can determine a power control signal based on the communication current collected from the RS485 chip unit, and control the RS485 power control circuit to supply power to the RS485 chip unit based on the power control signal.

[0010] In some embodiments, the signal transceiver further includes a self-transceiver circuit. The RS485 chip unit is connected to the MCU main control unit through the self-transceiver circuit. The self-transceiver circuit includes a sixth resistor, a seventh resistor, and an NMOS transistor. The RS485 chip unit includes an RO interface, an RE interface, a DE interface, and a DI interface. The RXD interface of the MCU main control unit is connected to the RO interface through a Schottky diode D48. The first end of the sixth resistor is connected to the RS485 power supply terminal, and the second end of the sixth resistor is connected to both the RE interface and the DE interface.

[0011] The TXD interface of the MCU main control unit is connected to the DI interface. The TXD terminal of the MCU main control unit is also connected to the RE interface and the DE interface in sequence through the seventh resistor and the NMOS transistor. The gate of the NMOS transistor is connected to the seventh resistor, the source of the NMOS transistor is connected to the ground terminal, and the drain of the NMOS transistor is connected to both the RE interface and the DE interface.

[0012] In some embodiments, a first bidirectional diode for reducing surge phenomena is connected in parallel with the matching circuit between the end of the differential signal transmission line at end A and the end of the differential signal transmission line at end B; wherein the first bidirectional diode is a bidirectional transient suppression diode or a bidirectional Zener diode.

[0013] In some embodiments, the terminal device includes a terminal device input terminal and a terminal device output terminal; the end of the differential signal transmission line at end A is connected to either the terminal device input terminal or the terminal device output terminal via a first fuse, and / or, the end of the differential signal transmission line at end B is connected to the other end of either the terminal device input terminal or the terminal device output terminal via a second fuse; wherein, the first fuse is used to provide overload protection, and the second fuse is used to provide overload protection.

[0014] In some embodiments, the end of the first resistor furthest from the first PMOS transistor is grounded through a second bidirectional diode; the end of the second resistor furthest from the second PMOS transistor is grounded through a third bidirectional diode; wherein the second bidirectional diode and the third bidirectional diode are bidirectional Zener diodes.

[0015] This specification provides a matching control method applied to an MCU main control unit in the matching control circuit described in any of the above embodiments. The method includes: acquiring the communication current between an RS485 chip unit and a terminal device; and acquiring communication success rate information between the MCU main control unit and the terminal device; wherein the communication success rate information can describe the packet loss situation in the communication between the MCU main control unit and the terminal device; determining matching information of a matching circuit based on the communication current and the communication success rate information; wherein the matching information can describe whether the terminal impedance matches the output impedance of the differential signal transmission line of the RS485 chip unit; and, if it is determined based on the matching information that impedance adjustment is required, outputting a target voltage signal to the matching circuit based on the matching information, so that the matching circuit adjusts the terminal impedance based on the target voltage signal.

[0016] In some embodiments, the method further includes: when the communication current is greater than or equal to a specified current threshold, outputting a high level through the second specified P3 interface of the MCU main control unit to disconnect the RS485 power supply terminal in the RS485 power control circuit.

[0017] In several embodiments provided in this specification, the matching control circuit of the signal transceiver includes an MCU main control unit, a signal transceiver, and a matching circuit. The MCU main control unit is connected to the signal transceiver, which is capable of signal transmission and reception based on an RS485 chip unit. The end of the differential signal transmission line of the RS485 chip unit in the signal transceiver is connected to the matching circuit and the terminal device. The matching circuit is used to adjust the terminal impedance to match the output impedance of the differential signal transmission line. The RS485 chip unit is connected to a current acquisition circuit, which is used to acquire the communication current between the RS485 chip unit and the terminal device. Based on the communication current and the communication success rate information between the MCU main control unit and the terminal device, the MCU main control unit can output a target voltage signal to the matching circuit, so that the matching circuit adjusts the terminal impedance based on the target voltage signal. In this way, it can automatically adapt to impedance changes, achieve intelligent matching, and improve the reliability of RS485 communication. Attached Figure Description

[0018] Figure 1a This is a schematic diagram of the matching control circuit provided in the embodiments of this specification;

[0019] Figure 1b This is another schematic diagram of the matching control circuit provided in the embodiments of this specification;

[0020] Figure 1c This is yet another schematic diagram of the matching control circuit provided in the embodiments of this specification;

[0021] Figure 2 This is a flowchart illustrating the matching control method provided in the embodiments of this specification.

[0022] In the attached figures, the following labels are used:

[0023] Q33: First PMOS transistor; Q32: Second PMOS transistor; Q30: Third PMOS transistor;

[0024] R207: First resistor; R208: Second resistor; R205: Third resistor; R199: Fourth resistor; R209: Fifth resistor; R201: Sixth resistor; R200: Seventh resistor; R202: Eighth resistor; R203: Ninth resistor; R206: Tenth resistor; R204: Eleventh resistor; R213: Twelfth resistor; R198: Thirteenth resistor; R197: Fourteenth resistor;

[0025] C107: First capacitor; C108: Second capacitor; Q31: NMOS transistor; C106: Filter capacitor; C105: Third capacitor;

[0026] D48: Schottky diode; U32: First bidirectional diode; U34: Second bidirectional diode; U35: Third bidirectional diode; F18: First fuse; F17: Second fuse;

[0027] R_EN: First transmission line. Detailed Implementation

[0028] To enable those skilled in the art to better understand the solutions described in this specification, the technical solutions in the embodiments of this specification will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this specification, and not all of them. Based on the embodiments in this specification, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this specification.

[0029] This specification provides a matching control circuit for a signal transceiver device, which may include an MCU main control unit, a signal transceiver device, and a matching circuit.

[0030] Specifically, please refer to Figure 1a and 1b The MCU main control unit is connected to the signal transceiver device, which can transmit and receive signals based on the self-transceiver circuit and RS485 chip unit.

[0031] In the signal transceiver device, the end of the differential signal transmission line of the RS485 chip unit is connected to the matching circuit and the terminal equipment. The matching circuit is used to adjust the terminal impedance to match the output impedance of the differential signal transmission line.

[0032] The RS485 chip unit is connected to a current acquisition circuit, which is used to acquire the communication current between the RS485 chip unit and the terminal device.

[0033] The MCU main control unit can output a target voltage signal to the matching circuit based on the communication current and the communication success rate information between the MCU main control unit and the terminal device, so that the matching circuit can adjust the terminal impedance based on the target voltage signal.

[0034] For example, the matching control circuit of the signal transceiver can be applied to a heating system.

[0035] In the above embodiments, based on the MCU main control unit, signal transceiver device and matching circuit in the matching control circuit, the target voltage signal can be output to the matching circuit through the communication current between the RS485 chip unit and the terminal device, and the communication success rate information between the MCU main control unit and the terminal device. This allows the matching circuit to adjust the terminal impedance based on the target voltage signal, satisfying the changes in terminal impedance caused by the device itself and the ambient temperature. Especially at higher communication baud rates and longer communication distances, it can achieve fine adjustment of terminal impedance. In this way, it can automatically adapt to impedance changes, achieve intelligent matching, and improve the reliability of RS485 communication.

[0036] In some implementations, please refer to [the relevant documentation]. Figure 1a and 1b The differential signal transmission line includes an A-end differential signal transmission line and a B-end differential signal transmission line. The matching circuit and the terminal equipment are connected in parallel between the ends of the A-end differential signal transmission line and the B-end differential signal transmission line.

[0037] The matching circuit includes a first PMOS transistor Q33, a second PMOS transistor Q32, a first resistor R207, a second resistor R208, and a third resistor R205.

[0038] The drain of the first PMOS transistor Q33 is connected to the end of the differential signal transmission line at terminal B through the first resistor R207. The source of the first PMOS transistor Q33 is connected to the source of the second PMOS transistor Q32. The drain of the second PMOS transistor Q32 is connected to the end of the differential signal transmission line at terminal A through the second resistor R208.

[0039] The first designated P1 interface of the MCU main control unit is simultaneously connected to the gate of the first PMOS transistor Q33, the gate of the second PMOS transistor Q32, and one end of the third resistor R205 via the first transmission line R_EN. The other end of the third resistor R205 is connected between the source of the first PMOS transistor Q33 and the source of the second PMOS transistor Q32. The MCU main control unit can transmit a target voltage signal based on the first transmission line R_EN to adjust the on-resistance of the first PMOS transistor Q33 and the second PMOS transistor Q32.

[0040] Here, P interface refers to parallel input / output interface, which can include P0, P1, P2, P3, etc. The first designated P1 interface of the MCU main control unit can be one of a series of P1 interfaces, such as P1.6.

[0041] In some implementations, please refer to [the relevant documentation]. Figure 1a and 1bThe matching control circuit may also include a two-stage RC low-pass filter circuit, which includes a fourth resistor R199, a fifth resistor R209, a first capacitor C107, and a second capacitor C108.

[0042] The fourth resistor R199 and the fifth resistor R209 are connected in series on the first transmission line R_EN between the first designated P1 interface of the MCU main control unit and the matching circuit.

[0043] One end of the first capacitor C107 is connected between the fourth resistor R199 and the fifth resistor R209, and the other end of the first capacitor C107 is grounded. One end of the second capacitor C108 is connected to the end of the fifth resistor R209 closest to the matching circuit, and the other end of the second capacitor C108 is grounded.

[0044] The two-stage RC low-pass filter circuit is used to perform low-pass filtering on the 16-bit pulse broadband modulated voltage signal output from the first designated P1 interface of the MCU main control unit to obtain the 16-bit pulse broadband modulated DAC voltage signal as the target voltage signal.

[0045] The magnitude of the target voltage signal can be any value in [0, VCC]. VCC is the power supply voltage at the main control unit power input terminal of the MCU main control unit.

[0046] The back-to-back connection of the first PMOS transistor Q33 and the second PMOS transistor Q32 gives the matching network bidirectional conduction characteristics. When the target voltage signal transmitted through the first transmission line R_EN is VCC, both PMOS transistors Q33 and Q32 are not conducting, resulting in bidirectional cutoff. When the target voltage signal transmitted through the first transmission line R_EN is 0, both PMOS transistors Q33 and Q32 conduct bidirectionally. As the target voltage signal transmitted through the first transmission line R_EN adjusts from 0 to VCC, the on-resistance of the first PMOS transistors Q33 and Q32 gradually increases, achieving dynamic adjustment of the on-resistance. In other words, based on the target voltage signal, the on-resistance of the first PMOS transistors Q33 and Q32 can be adjusted within an ohmic range, thereby dynamically adjusting the termination impedance and improving the stability of RS485 communication.

[0047] In some implementations, please refer to Figure 1c The matching control circuit may also include an RS485 power control circuit.

[0048] Specifically, the RS485 power control circuit includes a third PMOS transistor Q30 and an eighth resistor R202. The second designated P3 interface of the MCU main control unit is connected to the gate of the third PMOS transistor Q30 through the second transmission line. The source of the third PMOS transistor Q30 is connected to the power input terminal VCC of the main control unit, or in other words, to the supply voltage VCC. The drain of the third PMOS transistor Q30 serves as the RS485 power supply terminal for the RS485 chip unit, namely 485_VCC_A. The RS485 power supply terminal is used to supply power to the RS485 chip unit.

[0049] The first designated P3 interface of the MCU main control unit can be one of a series of P3 interfaces, such as P3.2.

[0050] One end of the eighth resistor R202 is connected to the second transmission line, and the other end is connected between the source of the third PMOS transistor Q30 and the power input terminal VCC of the main control unit.

[0051] The MCU main control unit can determine the power control signal based on the communication current collected from the RS485 chip unit, and control the RS485 power control circuit to supply power to the RS485 chip unit based on the power control signal.

[0052] In some implementations, please refer to [the relevant documentation]. Figure 1a and 1b In the signal transceiver device, the RS485 chip unit is connected to the MCU main control unit through a self-transceiver circuit, which includes a sixth resistor R201, a seventh resistor R200, and an NMOS transistor Q31. The RS485 chip unit includes RO interface, RE interface, DE interface, and DI interface.

[0053] The RXD interface of the MCU main control unit is connected to the RO interface through a Schottky diode D48.

[0054] The first end of the sixth resistor R201 is connected to the RS485 power supply terminal, namely 485_VCC_A, and the second end of the sixth resistor R201 is connected to both the RE interface and the DE interface.

[0055] The TXD interface of the MCU main control unit is connected to the DI interface. The TXD terminal of the MCU main control unit is also connected to both the RE and DE interfaces sequentially via the seventh resistor R200 and the NMOS transistor Q31. The gate of the NMOS transistor Q31 is connected to the seventh resistor R200. The source of the NMOS transistor Q31 is connected to ground (GND), and the drain of the NMOS transistor Q31 is connected to both the RE and DE interfaces. For example, the drain of the NMOS transistor Q31 can be connected between the second terminal of the sixth resistor R201 and the RE / DE interface.

[0056] For example, when the TXD interface is high, NMOS transistor Q31 is turned on, and the RS485 chip unit is in receive mode. When the TXD interface is low, NMOS transistor Q31 is not turned on, and the RS485 is in transmit mode. In this way, the signal transceiver can perform self-transmission and reception without the need for a separate I / O interface to control transmission and reception. Based on the transmit control of the TXD interface and the fast switching speed of NMOS transistor Q31, it can meet the switching needs of different baud rates, eliminating the need for high-cost dedicated chips.

[0057] The RS485 chip unit also includes an RS485 power interface, an RS485 ground interface, an A-line interface, and a B-line interface.

[0058] The A-line interface connects to the differential signal transmission line at end A, and the B-line interface connects to the differential signal transmission line at end B. The RS485 power interface connects to the RS485 power supply terminal, i.e., 485_VCC_A. The RS485 power interface is also grounded through the third capacitor C105, i.e., it is connected to the ground terminal GND through the third capacitor C105.

[0059] The current acquisition circuit includes a ninth resistor R203. The RS485 grounding interface of the RS485 chip unit is grounded through the ninth resistor R203. The third designated P1 interface of the MCU main control unit is connected between the RS485 grounding interface and the ninth resistor R203 through a tenth resistor R206.

[0060] The third designated P1 interface of the MCU main control unit can be one of a series of P1 interfaces, such as P1.0. The third designated P1 interface can be used as a communication port (COM).

[0061] For example, the communication current when the RS485 chip unit is in communication mode is different from the current when it is not in communication mode. Therefore, the MCU main control unit can perform real-time analysis on the communication current collected by the current acquisition circuit based on the third designated P1 interface, thereby determining the communication status.

[0062] As an example, when the RS485 chip unit is in normal communication mode, its communication current should be in the first current range. When the RS485 chip unit is static or not in communication mode, its current should be in the second current range. Therefore, after obtaining the communication current based on the third designated P1 interface, analysis is required. If the RS485 chip unit is in communication mode and the acquired communication current is not in the first current range, a line fault can be determined. If the RS485 chip unit is static and the acquired current is not in the second current range, a line fault can also be determined. If the RS485 chip unit is in communication mode and the acquired communication current is in the first current range, and the RS485 chip unit is static and the acquired current is in the second current range, but communication failure is determined based on communication success rate information, a target voltage signal can be generated to adjust the terminal impedance.

[0063] On the differential signal transmission line at end B, an eleventh resistor R204 is installed between the B-line interface and the matching circuit. On the differential signal transmission line at end A, a twelfth resistor R213 is installed between the A-line interface and the matching circuit.

[0064] The third designated P1 interface P1.0 of the MCU main control unit is connected to the B-end differential signal transmission line between the B-line interface and the matching circuit through the tenth resistor R206 and the thirteenth resistor R198 in sequence.

[0065] The RS485 power supply terminal is also connected to the differential signal transmission line at the A-end between the A-line interface and the matching circuit via the fourteenth resistor R197.

[0066] In some implementations, a first bidirectional diode U32 for reducing surge phenomena is connected in parallel with a matching circuit between the ends of the differential signal transmission lines at terminals A and B. This first bidirectional diode U32 is either a bidirectional transient voltage suppressor diode or a bidirectional Zener diode. A bidirectional transient voltage suppressor diode is also known as a TVS diode.

[0067] In some embodiments, the terminal device includes a terminal device input and a terminal device output. The end of the B-end differential signal transmission line is connected to either the terminal device input or the terminal device output via a first fuse F18, and / or, the end of the A-end differential signal transmission line is connected to the other end of the terminal device input or the terminal device output via a second fuse F17.

[0068] The first fuse is used to provide overload protection, and the second fuse is used to provide overload protection.

[0069] In some implementations, the end of the first resistor R207 away from the first PMOS transistor Q33 is grounded through the second bidirectional diode U34; the end of the second resistor R208 away from the second PMOS transistor Q32 is grounded through the third bidirectional diode U35; wherein the second bidirectional diode U34 and the third bidirectional diode U35 are bidirectional Zener diodes.

[0070] The MCU main control unit has a UCAP pin, and an external filter capacitor C106 is soldered on it to stabilize the working state of internal components such as the RC oscillator.

[0071] The MCU main control unit has a VCC / AVCC pin, which is connected to the supply voltage VCC. The MCU main control unit is an ADC-equipped main control unit with a reference voltage pin ADC_VRef+, which is connected to the supply voltage VCC. The MCU main control unit has ground pins Gnd / AGnd for grounding.

[0072] The MCU main control unit also has an EP pin, which acts as a heat dissipation pad. By grounding, it ensures good heat dissipation and helps with thermal management.

[0073] This specification provides a matching control method. Please refer to [link / reference]. Figure 2 , Figure 2 This is a flowchart illustrating a matching control method provided in this specification. This embodiment provides the method operation steps as shown in the flowchart, but based on conventional or non-inventive methods, more or fewer operation steps may be included. The order of steps listed in the embodiment is merely one possible execution order among many, and does not represent the only possible execution order. In actual system or server product execution, the method can be executed sequentially or in parallel (e.g., in a parallel processor or multi-threaded processing environment). This matching control method can be applied to the MCU main control unit in a matching control circuit, specifically as follows... Figure 2 As shown, the matching control method may include the following steps.

[0074] Step S210: Obtain the communication current between the RS485 chip unit and the terminal device, and obtain the communication success rate information between the MCU main control unit and the terminal device.

[0075] Among them, the communication success rate information can describe the packet loss situation in the communication between the MCU main control unit and the terminal device.

[0076] Step S220: Based on the communication current and communication success rate information, determine the matching information of the matching circuit; wherein, the matching information can describe whether the terminal impedance matches the output impedance of the differential signal transmission line of the RS485 chip unit.

[0077] Step S230: If impedance adjustment is required based on the matching information, a target voltage signal is output to the matching circuit based on the matching information, so that the matching circuit adjusts the terminal impedance based on the target voltage signal.

[0078] In some implementations, the matching control method may further include: when the communication current is greater than or equal to a specified current threshold, outputting a high level through the second specified P3 interface of the MCU main control unit to disconnect the RS485 power supply terminal in the RS485 power control circuit, thereby stopping the power supply to the RS485 chip unit.

[0079] For example, the high level output of the MCU main control unit means that the power control signal RS485_A-ON is output to a high level through the second designated P3 interface to control the third PMOS transistor Q30 to be turned off.

[0080] It is understood that the specific examples in this document are only intended to help those skilled in the art better understand the embodiments described herein, and are not intended to limit the scope of the invention.

[0081] It is understood that in the various embodiments described in this specification, the sequence number of each process does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments described in this specification.

[0082] It is understood that the various implementation methods described in this specification can be implemented individually or in combination, and the implementation methods in this specification are not limited in this respect.

[0083] Unless otherwise stated, all technical and scientific terms used in the embodiments of this specification have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the scope of this specification. The term "and / or" as used in this specification includes any and all combinations of one or more of the associated listed items. The singular forms "a," "the," and "the" as used in the embodiments of this specification and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0084] The above description is merely a specific embodiment of this specification, but the scope of protection of this invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this specification should be included within the scope of protection of this specification. Therefore, the scope of protection of this invention should be determined by the scope of the claims.

Claims

1. A matching control circuit for a signal transceiver, characterized in that, Includes MCU main control unit, signal transceiver device and matching circuit; The MCU main control unit is connected to the signal transceiver device, and the signal transceiver device can perform signal transmission and reception based on the RS485 chip unit. The end of the differential signal transmission line of the RS485 chip unit in the signal transceiver is connected to the matching circuit and the terminal device. The matching circuit is used to adjust the terminal impedance to match the output impedance of the differential signal transmission line. The RS485 chip unit is connected to a current acquisition circuit, which is used to acquire the communication current between the RS485 chip unit and the terminal device. The MCU main control unit can output a target voltage signal to the matching circuit based on the communication current and the communication success rate information between the MCU main control unit and the terminal device, so that the matching circuit can adjust the terminal impedance based on the target voltage signal. The differential signal transmission line includes an A-end differential signal transmission line and a B-end differential signal transmission line. The matching circuit is connected in parallel with the terminal device between the end of the A-end differential signal transmission line and the end of the B-end differential signal transmission line. The matching circuit includes a first PMOS transistor, a second PMOS transistor, a first resistor, a second resistor, and a third resistor; The drain of the first PMOS transistor is connected to the end of the differential signal transmission line at terminal B through the first resistor, the source of the first PMOS transistor is connected to the source of the second PMOS transistor, and the drain of the second PMOS transistor is connected to the end of the differential signal transmission line at terminal A through the second resistor. The first designated P1 interface of the MCU main control unit is simultaneously connected to the gate of the first PMOS transistor, the gate of the second PMOS transistor, and one end of the third resistor through the first transmission line. The other end of the third resistor is connected between the source of the first PMOS transistor and the source of the second PMOS transistor. The MCU main control unit can transmit the target voltage signal based on the first transmission line to adjust the on-resistance of the first PMOS transistor and the second PMOS transistor.

2. The matching control circuit according to claim 1, characterized in that, The matching control circuit also includes a two-stage RC low-pass filter circuit, which includes a fourth resistor, a fifth resistor, a first capacitor, and a second capacitor. The fourth resistor and the fifth resistor are connected in series on the first transmission line between the first designated P1 interface of the MCU main control unit and the matching circuit; One end of the first capacitor is connected between the fourth resistor and the fifth resistor, and the other end of the first capacitor is grounded; one end of the second capacitor is connected to the end of the fifth resistor closest to the matching circuit, and the other end of the second capacitor is grounded. The secondary RC low-pass filter circuit is used to perform low-pass filtering on the 16-bit pulse broadband modulated voltage signal output from the first designated P1 interface of the MCU main control unit to obtain a 16-bit pulse broadband modulated DAC voltage signal as the target voltage signal; wherein, the target voltage signal is any value in [0, VCC], and VCC is the power supply voltage of the main control unit power input terminal of the MCU main control unit.

3. The matching control circuit according to claim 1, characterized in that, The matching control circuit also includes an RS485 power control circuit. The RS485 power control circuit includes a third PMOS transistor. The second designated P3 interface of the MCU main control unit is connected to the gate of the third PMOS transistor through a second transmission line. The source of the third PMOS transistor is connected to the power input terminal of the main control unit. The drain of the third PMOS transistor serves as the RS485 power supply terminal of the RS485 chip unit. The RS485 power supply terminal is used to supply power to the RS485 chip unit. The MCU main control unit can determine the power control signal based on the communication current collected from the RS485 chip unit, and control the RS485 power control circuit to supply power to the RS485 chip unit based on the power control signal.

4. The matching control circuit according to claim 3, characterized in that, The signal transceiver device further includes a self-transceiver circuit. The RS485 chip unit is connected to the MCU main control unit through the self-transceiver circuit. The self-transceiver circuit includes a sixth resistor, a seventh resistor, and an NMOS transistor. The RS485 chip unit includes an RO interface, an RE interface, a DE interface, and a DI interface. The RXD interface of the MCU main control unit is connected to the RO interface through a Schottky diode; The first end of the sixth resistor is connected to the RS485 power supply terminal, and the second end of the sixth resistor is connected to both the RE interface and the DE interface. The TXD interface of the MCU main control unit is connected to the DI interface. The TXD terminal of the MCU main control unit is also connected to the RE interface and the DE interface in sequence through the seventh resistor and the NMOS transistor. The gate of the NMOS transistor is connected to the seventh resistor, the source of the NMOS transistor is connected to the ground terminal, and the drain of the NMOS transistor is connected to both the RE interface and the DE interface.

5. The matching control circuit according to claim 1, characterized in that, Between the end of the differential signal transmission line at end A and the end of the differential signal transmission line at end B, a first bidirectional diode for reducing surge phenomena is connected in parallel with the matching circuit; wherein, the first bidirectional diode is a bidirectional transient suppression diode or a bidirectional Zener diode.

6. The matching control circuit according to claim 1, characterized in that, The terminal device includes a terminal device input terminal and a terminal device output terminal; The end of the differential signal transmission line at end A is connected to either the input end or the output end of the terminal device via a first fuse, and / or the end of the differential signal transmission line at end B is connected to the other end of either the input end or the output end of the terminal device via a second fuse; wherein, the first fuse is used to provide overload protection, and the second fuse is used to provide overload protection.

7. The matching control circuit according to claim 1, characterized in that, The end of the first resistor furthest from the first PMOS transistor is grounded through a second bidirectional diode; the end of the second resistor furthest from the second PMOS transistor is grounded through a third bidirectional diode; wherein the second bidirectional diode and the third bidirectional diode are bidirectional Zener diodes.

8. A matching control method, characterized in that, The method, applied to the MCU main control unit in any of the matching control circuits described in claims 1 to 7, comprises: The communication current between the RS485 chip unit and the terminal device is obtained, and the communication success rate information between the MCU main control unit and the terminal device is obtained; wherein, the communication success rate information can describe the packet loss situation in the communication between the MCU main control unit and the terminal device; Based on the communication current and the communication success rate information, the matching information of the matching circuit is determined; wherein, the matching information can describe whether the terminal impedance matches the output impedance of the differential signal transmission line of the RS485 chip unit. If impedance adjustment is required based on the matching information, a target voltage signal is output to the matching circuit based on the matching information, so that the matching circuit adjusts the terminal impedance based on the target voltage signal.

9. The matching control method according to claim 8, characterized in that, The method further includes: When the communication current is greater than or equal to the specified current threshold, a high level is output through the second specified P3 interface of the MCU main control unit to disconnect the RS485 power supply terminal in the RS485 power control circuit.

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