USB (Universal Serial Bus)-to-multipath RS485 circuit

Abstract

The utility model discloses a USB (Universal Serial Bus) to multipath RS485 (Recommended Standard 485) circuit. The circuit comprises a USB interface circuit, a level conversion circuit and a power supply circuit, the input end of the USB interface circuit is connected with a USB port, the output end of the USB interface circuit is connected with the input end of the level conversion circuit, and the output end of the level conversion circuit outputs multiple paths of RS485 level signals. According to the serial port controller, USB signals output by the USB port are converted into TTL level signals through the USB interface circuit, the TTL level signals output by the USB interface circuit are converted into multiple RS485 level signals through the level conversion circuit, one USB interface is converted into multiple RS485 interfaces, and the problem that a traditional serial port controller cannot generate a large number of RS485 interfaces is solved. The installation and debugging process is simpler and more convenient, and tedious steps of manual configuration and connection are reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of circuits, and particularly relates to a USB-to-multiple-RS485 circuit. Background Art

[0002] In the field of industrial control, serial communication is a commonly used technology in the product development process. Usually, one USB port can meet the communication requirements of a single serial port. However, when multiple serial ports need to use the USB port simultaneously, multiple connecting lines are required between the computer and the controller. Traditional serial controllers cannot directly generate a large number of RS485 control interfaces, resulting in a cumbersome installation and debugging process. Content of the Utility Model

[0003] Therefore, an embodiment of the utility model provides a USB-to-multiple-RS485 circuit to solve the problem in the prior art that traditional serial controllers cannot directly generate a large number of RS485 control interfaces, resulting in a cumbersome installation and debugging process.

[0004] To achieve the above object, the embodiment of the utility model provides the following technical solutions:

[0005] A USB-to-multiple-RS485 circuit includes a USB interface circuit, a level conversion circuit, and a power supply circuit;

[0006] The input end of the USB interface circuit is connected to the USB port, the output end of the USB interface circuit is connected to the input end of the level conversion circuit, and the output end of the level conversion circuit outputs multiple RS485 level signals;

[0007] The input end of the power supply circuit is connected to the USB port, and the output end of the power supply circuit is respectively connected to the power supply end of the USB interface circuit and the power supply end of the level conversion circuit;

[0008] Wherein, the power supply circuit is used to provide a power supply voltage to the USB interface circuit and the level conversion circuit, the USB interface circuit is used to convert the USB signal output by the USB port into a TTL level signal, and the level conversion circuit is used to convert the TTL level signal output by the USB interface circuit into multiple RS485 level signals.

[0009] Optionally, the level conversion circuit includes a first chip U1, and the first chip U1 includes an AMS1117 chip; the input end of the first chip U1 is connected to the USB port, and the output end of the first chip U1 is a +3.3V voltage output end.

[0010] Optionally, the first pin of the USB port P1 is connected to the input end of the first chip U1 through a first fuse F1. The input end of the first chip U1 is also divided into three paths. One path is connected to the +5V voltage output end, another path is grounded through a first capacitor C1, and the third path is grounded through a second capacitor C2. The grounding end of the first chip U1 is grounded. The output end of the first chip U1 is divided into three paths. One path is grounded through a third capacitor C3, another path is grounded through a fourth capacitor C4, and the third path is the +3.3V voltage output end.

[0011] Optionally, the USB interface circuit includes a second chip U2, and the second chip U2 includes a CH348Q chip.

[0012] Optionally, the second pin of the USB port P1 is connected to the 42nd pin of the second chip U2, the third pin of the USB port P1 is connected to the 43rd pin of the second chip U2, and the fourth pin of the USB port P1 is grounded.

[0013] Optionally, the VCC pin of the second chip U2 is divided into two paths. One path is connected to the +3.3V voltage output end, and the other path is grounded through a power decoupling capacitor.

[0014] Optionally, the level conversion circuit includes multiple MAX485ESA chips;

[0015] The input end of each MAX485ESA chip among the multiple MAX485ESA chips is respectively connected to the output end of the second chip U2, and the output end of each MAX485ESA chip outputs an RS485 level signal.

[0016] Optionally, the level conversion circuit includes multiple MAX485ESA chips;

[0017] The input end of each MAX485ESA chip among the multiple MAX485ESA chips is respectively connected to the output end of the second chip U2, and the output end of each MAX485ESA chip outputs an RS485 level signal.

[0018] Optionally, the USB to multi-channel RS485 circuit further includes a reset circuit;

[0019] The reset circuit includes a second resistor R2 and a seventh capacitor C7;

[0020] One end of the second resistor R2 is connected to the +3.3V voltage output end. The other end of the second resistor R2 is divided into two paths. One path is connected to the 7th pin of the second chip U2, and the other path is grounded through the seventh capacitor C7.

[0021] The utility model has at least the following beneficial effects:

[0022] The utility model provides a USB to multi-channel RS485 circuit, which includes a USB interface circuit, a level conversion circuit and a power supply circuit; the input end of the USB interface circuit is connected to a USB port, the output end of the USB interface circuit is connected to the input end of the level conversion circuit, and the output end of the level conversion circuit outputs multi-channel RS485 level signals; the input end of the power supply circuit is connected to the USB port, and the output end of the power supply circuit is respectively connected to the power supply end of the USB interface circuit and the power supply end of the level conversion circuit. In the utility model, the USB signal output by the USB port is converted into a TTL level signal through the USB interface circuit, and the TTL level signal output by the USB interface circuit is converted into multi-channel RS485 level signals through the level conversion circuit, realizing the conversion of one USB interface into multi-channel RS485 interfaces, solving the problem that traditional serial port controllers cannot generate a large number of RS485 interfaces, making the installation and debugging process more convenient, and reducing the cumbersome steps of manual configuration and connection. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the prior art and the utility model, the following will briefly introduce the drawings required for describing the prior art and the embodiments of the utility model. Obviously, the drawings in the following description are only exemplary, and for those of ordinary skill in the art, without creative efforts, other drawings can be obtained by extending according to the provided drawings.

[0024] The structures, ratios, sizes, etc. shown in this specification are only used to cooperate with the content disclosed in the specification for those who are familiar with this technology to understand and read, and are not used to limit the limiting conditions under which the utility model can be implemented. Any modification of the structure, change of the proportional relationship or adjustment of the size, without affecting the effects that the utility model can produce and the purposes that can be achieved, should still fall within the scope covered by the technical content disclosed in the utility model.

[0025] Figure 1 It is a circuit principle block diagram of a USB to multi-channel RS485 circuit provided by an embodiment of the utility model;

[0026] Figure 2 It is a circuit schematic diagram of a power supply circuit and a USB port provided by an embodiment of the utility model;

[0027] Figure 3 It is a circuit schematic diagram of a USB interface circuit provided by an embodiment of the utility model;

[0028] Figure 4 It is a circuit schematic diagram of a level conversion circuit provided by an embodiment of the utility model. Detailed implementation manners

[0029] In order to make the objectives, technical solutions and advantages of the present application more clear and understandable, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0030] In the description of the present utility model, unless otherwise specified, the meaning of "a plurality of" is two or more. The terms "first", "second", "third", "fourth", etc. (if any) in the description and claims of the present utility model and the above-mentioned drawings are intended to distinguish the objects being referred to. For a solution with a time sequence process, such a term expression does not necessarily need to be understood as describing a specific order or sequence. For a solution of a device structure, such a term expression also does not distinguish the importance level and positional relationship, etc.

[0031] In addition, the terms "comprising", "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units does not necessarily need to be limited to those steps or units that are clearly listed, but may also include other steps or units that are inherent to these processes, methods, products or devices but are not clearly listed, or steps or units added by further optimized solutions based on the concept of the present utility model.

[0032] As Figure 1 shown, a USB to multi-channel RS485 circuit includes a USB interface circuit, a level conversion circuit and a power supply circuit;

[0033] The input end of the USB interface circuit is connected to a USB port, the output end of the USB interface circuit is connected to the input end of the level conversion circuit, and the output end of the level conversion circuit outputs multi-channel RS485 level signals;

[0034] The input end of the power supply circuit is connected to the USB port, and the output end of the power supply circuit is respectively connected to the power supply end of the USB interface circuit and the power supply end of the level conversion circuit;

[0035] Among them, the power supply circuit is used to provide a power supply voltage for the USB interface circuit and the level conversion circuit, the USB interface circuit is used to convert the USB signal output by the USB port into a TTL level signal, and the level conversion circuit is used to convert the TTL level signal output by the USB interface circuit into multi-channel RS485 level signals.

[0036] It should be noted that the present utility model provides a solution for outputting multiple RS485 signals that can not only ensure communication speed but also reduce costs by expanding the serial port of the USB port, solving the problem that multiple USB ports are required when connecting multiple 485 serial ports simultaneously, making installation and debugging convenient and the serial port cable easy to plug and unplug.

[0037] It should be noted that the present utility model solves the problem of complex wiring for connecting multiple RS485 through the USB port, and avoids the corresponding serial port numbers from being reconfigured, improving work efficiency.

[0038] The present utility model provides a USB-to-multiple-RS485 circuit, including a USB interface circuit, a level conversion circuit, and a power supply circuit; the input end of the USB interface circuit is connected to the USB port, the output end of the USB interface circuit is connected to the input end of the level conversion circuit, and the output end of the level conversion circuit outputs multiple RS485 level signals; the input end of the power supply circuit is connected to the USB port, and the output end of the power supply circuit is respectively connected to the power supply end of the USB interface circuit and the power supply end of the level conversion circuit. In the present utility model, the USB signal output from the USB port is converted into a TTL level signal through the USB interface circuit, and the level conversion circuit is used to convert the TTL level signal output from the USB interface circuit into multiple RS485 level signals, realizing the conversion of one USB interface into multiple RS485 interfaces, solving the problem that traditional serial port controllers cannot generate a large number of RS485 interfaces, making the installation and debugging process more convenient and reducing the cumbersome steps of manual configuration and connection.

[0039] As Figure 2 shown, in an embodiment of the present application, the level conversion circuit includes a first chip U1, and the first chip U1 includes an AMS1117 chip; the input end of the first chip U1 is connected to the USB port, and the output end of the first chip U1 is a +3.3V voltage output end.

[0040] In this embodiment, the reason for selecting the AMS1117 chip is that the working voltage of the CH348Q chip is 3.3V, and it is necessary to stabilize the 5V power supply from the USB bus to 3.3V.

[0041] As Figure 2As shown, in an embodiment of the present application, the first pin of the USB port P1 is connected to the input end of the first chip U1 through the first fuse F1. The input end of the first chip U1 is also divided into three paths. One path is connected to the +5V voltage output end, another path is grounded through the first capacitor C1, and the third path is grounded through the second capacitor C2. The ground end of the first chip U1 is grounded. The output end of the first chip U1 is divided into three paths. One path is grounded through the third capacitor C3, another path is grounded through the fourth capacitor C4, and the third path is the +3.3V voltage output end.

[0042] In this embodiment, the USB bus includes a pair of 5V power lines and a pair of data signal lines. Usually, the +5V power line is red, the ground line is black, the D+ signal line is green, and the D- signal line is white. The power current provided by the USB bus can reach 500mA.

[0043] As Figure 3 shown, in an embodiment of the present application, the USB interface circuit includes a second chip U2, and the second chip U2 includes a CH348Q chip.

[0044] It should be noted that the CH348Q chip is a high-speed USB bus chip conversion chip. Through the CH348Q chip, the USB to eight asynchronous serial port functions can be realized, which is used to expand the asynchronous serial port for the computer. Figure 3 In the CH348Q chip, the signal lines can be only connected to RXDx, TXDx, and the common ground wire. Other signals CTSx, RTSx, TNOWx can be selected according to needs and can be left floating when not needed.

[0045] P2, P3, P4, P5, P6, P7, P8, and P9 are the TTL connection pins of each serial port, including pins such as VCC, GND, RXDx, TXDx, RTSx, CTSx, and DTRx / TNOWx. P2, P3, P4, and P5 are used to implement the RS485 signal conversion. If you want to implement signal conversions such as TTL to RS232, you can select the connection pins P6, P7, P8, and P9.

[0046] As Figure 2 and Figure 3 shown, in an embodiment of the present application, the second pin of the USB port P1 is connected to the 42nd pin of the second chip U2, the third pin of the USB port P1 is connected to the 43rd pin of the second chip U2, and the fourth pin of the USB port P1 is grounded.

[0047] As Figure 3 shown, in an embodiment of the present application, the VCC pin of the second chip U2 is divided into two paths. One path is connected to the +3.3V voltage output end, and the other path is grounded through a power decoupling capacitor.

[0048] It should be noted that the VCC pin of the CH348Q chip inputs a power supply voltage of 3.3V, and a power supply decoupling capacitor with a capacitance of about 0.1uF should be externally connected to each power supply pin. For example, Figure 3 as shown, the eighth capacitor C8, the eleventh capacitor C11, the twelfth capacitor C12, and the thirteenth capacitor C13 are the power supply decoupling capacitors.

[0049] such as Figure 4 as shown, in an embodiment of the present application, the level conversion circuit includes multiple MAX485ESA chips;

[0050] The input end of each MAX485ESA chip among the multiple MAX485ESA chips is respectively connected to the output end of the second chip U2, and the output end of each MAX485ESA chip outputs an RS485 level signal.

[0051] It should be noted that the CH348Q chip realizes USB to TTL serial port and cannot directly output RS485 level signal. It is necessary to convert the TTL level signal into an RS485 level signal through a level conversion circuit.

[0052] The level conversion circuit includes multiple level conversion chips. The level conversion chips are selected as MAX485ESA chips, which convert the TTL level into a differential signal for transmission, and have advantages such as strong anti-interference ability and long transmission distance.

[0053] such as Figure 3 as shown, in an embodiment of the present application, the USB to multi-channel RS485 circuit further includes a clock oscillation circuit;

[0054] The clock oscillation circuit includes a first crystal X1, a fifth capacitor C5, and a sixth capacitor C6;

[0055] One end of the first crystal X1 is divided into two paths. One path is connected to the 6th pin of the second chip U2, and the other path is grounded through the sixth capacitor C6. The other end of the first crystal X1 is divided into two paths. One path is connected to the 5th pin of the second chip U2, and the other path is grounded through the fifth capacitor C5.

[0056] It should be noted that the first crystal X1, the fifth capacitor C5, and the sixth capacitor C6 constitute a clock oscillation circuit for CH348; the frequency of the first crystal X1 is 8MHz ± 0.4%, and the fifth capacitor C5 and the sixth capacitor C6 are monolithic or high-frequency ceramic capacitors with a capacitance of about 22pF.

[0057] such as Figure 3 as shown, in an embodiment of the present application, the USB to multi-channel RS485 circuit further includes a reset circuit;

[0058] The reset circuit includes a second resistor R2 and a seventh capacitor C7;

[0059] One end of the second resistor R2 is connected to the +3.3V voltage output terminal, and the other end of the second resistor R2 is divided into two paths. One path is connected to the 7th pin of the second chip U2, and the other path is grounded through the seventh capacitor C7.

[0060] It should be noted that the second resistor R2 and the seventh capacitor C7 included in the reset circuit are optional components.

[0061] For the USB-to-multiple-RS485 circuit provided by the present invention, during circuit manufacturing, first draw the schematic diagram and the PCB; secondly, have the PCB manufactured by an external PCB manufacturer and perform SMT soldering on the PCB; finally, test the PCB after soldering is completed, and finalize it after successful testing.

[0062] Components: According to the BOM list of the PCB, purchase a microprocessor, resistors, inductors, capacitors, relays, connectors, etc. from reliable component manufacturers.

[0063] Circuit board: Manufactured by a professional circuit board manufacturer. Send the Gerber file to the PCBA manufacturer, and also give the purchased components to the manufacturer for SMT soldering.

[0064] The above-described embodiments only represent the specific implementation manners of the present invention, and their descriptions are relatively specific and detailed, but should not be construed as limiting the scope of the patent of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention.

Claims

1. A USB to multi-channel RS485 circuit, characterized in that: Including USB interface circuit, level conversion circuit and power supply circuit; The input end of the USB interface circuit is connected to the USB port, the output end of the USB interface circuit is connected to the input end of the level conversion circuit, and the output end of the level conversion circuit outputs multiple RS485 level signals; The input end of the power supply circuit is connected to the USB port, and the output end of the power supply circuit is respectively connected to the power supply end of the USB interface circuit and the power supply end of the level conversion circuit; Among them, the power supply circuit is used to provide power supply voltage to the USB interface circuit and the level conversion circuit, the USB interface circuit is used to convert the USB signal output by the USB port into a TTL level signal, and the level conversion circuit is used to convert the TTL level signal output by the USB interface circuit into multiple RS485 level signals.

2. A USB to multi-channel RS485 circuit according to claim 1, characterized in that: The level conversion circuit includes a first chip U1, and the first chip U1 includes an AMS1117 chip; the input end of the first chip U1 is connected to the USB port, and the output end of the first chip U1 is a +3.3V voltage output end.

3. A USB to multi-channel RS485 circuit according to claim 2, characterized in that: The first pin of the USB port P1 is connected to the input end of the first chip U1 via the first fuse F1. The input end of the first chip U1 is also divided into three paths, one path is connected to the +5V voltage output end, another path is grounded via the first capacitor C1, and the third path is grounded via the second capacitor C2; the ground end of the first chip U1 is grounded; the output end of the first chip U1 is divided into three paths, one path is grounded via the third capacitor C3, another path is grounded via the fourth capacitor C4, and the third path is the +3.3V voltage output end.

4. A USB to multi-channel RS485 circuit according to claim 3, characterized in that: The USB interface circuit includes a second chip U2, and the second chip U2 includes a CH348Q chip.

5. A USB to multi-channel RS485 circuit according to claim 4, characterized in that: The second pin of the USB port P1 is connected to the 42nd pin of the second chip U2 , the third pin of the USB port P1 is connected to the 43rd pin of the second chip U2 , and the fourth pin of the USB port P1 is grounded.

6. A USB to multi-channel RS485 circuit according to claim 4, characterized in that: The VCC pin of the second chip U2 is divided into two paths, one path is connected to the +3.3V voltage output terminal, and the other path is grounded through a power decoupling capacitor.

7. A USB to multi-channel RS485 circuit according to claim 4, characterized in that: The level conversion circuit includes a plurality of MAX485ESA chips; The input end of each of the multiple MAX485ESA chips is respectively connected to the output end of the second chip U2, and the output end of each of the MAX485ESA chips outputs an RS485 level signal.

8. A USB to multi-channel RS485 circuit according to claim 4, characterized in that: The USB to multi-channel RS485 circuit also includes a clock oscillation circuit; The clock oscillation circuit includes a first crystal X1, a fifth capacitor C5 and a sixth capacitor C6; One end of the first crystal X1 is divided into two paths, one path is connected to the 6th pin of the second chip U2, and the other path is grounded through the sixth capacitor C6; the other end of the first crystal X1 is divided into two paths, one path is connected to the 5th pin of the second chip U2, and the other path is grounded through the fifth capacitor C5.

9. A USB to multi-channel RS485 circuit according to claim 4, characterized in that: The USB to multi-channel RS485 circuit also includes a reset circuit; The reset circuit includes a second resistor R2 and a seventh capacitor C7; One end of the second resistor R2 is connected to the +3.3V voltage output terminal, and the other end of the second resistor R2 is divided into two paths, one path is connected to the seventh pin of the second chip U2, and the other path is grounded via the seventh capacitor C7.

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