Serial port communication conversion circuit based on USB interface

Abstract

The utility model discloses a serial port communication conversion circuit based on a USB (Universal Serial Bus) interface, which comprises a USB-to-8 serial port chip, two serial port-to-CAN (Controller Area Network) chips, a serial port-to-RS232 (Recommended Standard 232) chip, four serial port-to-RS485 (Recommended Standard 485) chips and a level control chip, downlink ports of the USB-to-8 serial port chip are connected with the serial port conversion chips and the level control chip and used for expanding USB ports into two CAN communication interfaces, one 232 communication interface, four 485 communication interfaces and one level control circuit, and the level control chip outputs four level control interfaces and is connected with four relays respectively. The control circuit is used for controlling on-off of the four relays. According to the utility model, under the design of a single-stage conversion circuit, the communication requirement of converting a single USB interface into multiple serial ports is met, the compatibility and expansibility are strong, the conversion of various different communication protocol interfaces is met, and the communication efficiency is high.

Description

TECHNICAL FIELD

[0001] The utility model belongs to the technical field of electronic communication, specifically relates to a serial communication conversion circuit based on USB interface. BACKGROUND

[0002] When microprocessor reads part terminal equipment data, need to connect more serial equipment and real-time requirement is higher, because microprocessor self -contained serial port quantity is less, often need to expand and convert to serial port.

[0003] There are two methods to realize the interface between the serial port expansion chip and the microprocessor in the prior art, one is to connect the MCU as the control signal between the expansion chip and the microprocessor, which limits the number of expanded serial ports and increases the complexity of the system, and cannot meet the demand.The other is to expand the serial port through the USB interface of the microprocessor, because the number of USB interfaces of general microprocessors is less, the number of expandable serial ports is less, and the microprocessor resources are occupied or multiple USBs are converted by a single USB expansion chip, then the converted USB interfaces are connected with the USB-to-serial chip to expand more serial ports. The number of expanded serial ports is large, but the multi-stage circuit design is complex and occupies a large space.

[0004] In summary, the more serial ports expanded by the current implementation mode, the more microprocessor resources and peripheral circuit components needed, which occupies a large space, and is too high for small volume products, cannot adapt to more customer groups, and affects the widespread use of products. If a multi-stage expansion scheme is used, because the software complexity of the existing MCU is getting higher and higher, the real-time performance of the program is decreasing, which cannot meet the requirement of communication mode switching speed, and cannot meet the demand for some high-speed switching conditions. Utility model content

[0005] The utility model aims at providing a serial communication conversion circuit based on USB interface, realizing multi-channel serial port expansion, expanding one USB interface to at most 8 general serial ports, and converting the serial ports to other types of communication interfaces.

[0006] In order to achieve the above object, the utility model adopts the technical scheme: a serial port communication conversion circuit based on USB interface, the circuit includes 1 USB to 8 serial port chip, 2 serial port to CAN chip, 1 serial port to RS232 chip, 4 serial port to RS485 chip, 1 level control chip, the uplink port of USB to 8 serial port chip is connected with the USB interface of microprocessor, the downlink port of USB to 8 serial port chip is connected with each serial port conversion chip and level control chip, is used to expand USB port into 2 CAN communication interfaces, 1 232 communication interface, 4 485 communication interfaces and 1 level control circuit, the level control chip outputs 4 level control interfaces and is connected four-way relay respectively, is used for the control four-way relay's opening and breaking.

[0007] As a further preferred embodiment of the present application, the USB to 8 serial port chip uses a CH348 chip.

[0008] As a further preferred embodiment of the present application, the microprocessor uses an STM32X processing chip.

[0009] As a further preferred embodiment of the present application, the 42nd pin and the 43rd pin of the CH348 chip are connected to the USB interface of the microprocessor.

[0010] As a further preferred embodiment of the present application, the serial port to CAN chip uses a MCP2542FD-H / SN chip.

[0011] As a further preferred embodiment of the present application, the serial port to RS232 chip uses a MAX3232ID chip.

[0012] As a further preferred embodiment of the present application, the serial port to RS485 chip uses a MAX345ESA chip.

[0013] As a further preferred embodiment of the present application, the level control chip uses a STC8G1K17 chip.

[0014] Compared with the prior art, the utility model has the following advantages and beneficial effects:

[0015] (1) the circuit can realize the expansion of 8 serial ports through a USB interface (the expansion of a maximum of 32 serial ports through two-stage expansion), and is suitable for application environments that need to expand more serial ports.

[0016] (2) the circuit avoids expanding serial ports through a bus mode, reduces the occupation of microprocessor resources as much as possible, and saves the interface resources of the microprocessor.

[0017] (3) the circuit is simple to realize, low in hardware cost, and stable and efficient in serial port communication.

[0018] (4) This circuit has a rich set of expansion circuits to meet the needs of various control systems for connecting external devices.

[0019] In summary, this utility model avoids the problem of excessively large product designs that cannot meet the needs of space-constrained applications such as cabinets and control boxes by using a relatively simple peripheral circuit scheme. With a single-stage conversion circuit design, it meets the requirements of converting a single USB interface to multiple serial port communication, exhibiting strong compatibility and expandability, satisfying the conversion of various communication protocol interfaces, and achieving high communication efficiency. Attached Figure Description

[0020] Figure 1 The overall architecture diagram of the serial port expansion circuit based on the USB interface provided by this utility model.

[0021] Figure 2 Schematic diagram of a single USB to 8 serial port chip circuit

[0022] Figure 3 This is a schematic diagram of a serial-to-two-channel CAN communication chip circuit.

[0023] Figure 4 This is a schematic diagram of a serial-to-RS232 communication chip circuit.

[0024] Figure 5 This is a schematic diagram of a serial port to two-channel RS485 communication chip circuit.

[0025] Figure 6 This is a schematic diagram of a serial port to 1-channel relay switch circuit. Detailed Implementation

[0026] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present utility model. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments.

[0027] like Figure 1 As shown in the figure, this embodiment provides a serial port expansion circuit based on a USB interface. Its structure includes a microprocessor, a USB-to-8 serial port chip CH348, and peripheral circuits such as a crystal oscillator and reset circuit. The upstream port of the USB-to-8 serial port chip is connected to the microprocessor via a USB port, and its downstream port is connected to the serial port of the expansion chip via eight serial chips.

[0028] Specifically, the microprocessor uses an STM32X MCU, such as... Figure 2As shown, the USB-to-8 serial port chip adopts CH348Q chip, the 42th and 43th pins of which are connected to the USB interface of the microprocessor; in this example, each USB-to-8 serial port chip expands 8 serial ports, taking the first serial port as an example, the 30th and 31th pins of the single USB-to-8 serial port chip are connected to the 1st and 4th pins of the serial port-to-RS485 chip respectively, for converting the first serial port into RS485 interface.

[0029] As shown in Figure 2 , Figure 3 , Figure 4 , Figure 5 , in this example, the serial port expansion circuit, taking the serial port-to-CAN chip as an example, the 1st and 4th pins of the serial port-to-CAN chip MCP2542FD-H / SN are connected to the 40th and 41th pins of the single USB-to-8 serial port chip CH348Q interface respectively, and the serial ports 4 and 5 converted from the USB interface are further expanded into two-way CAN communication circuit. Similarly, the other serial port pins of the single USB-to-8 serial port chip are also connected to the serial port pins of the conversion chips, the serial port 6 is further expanded into one-way RS232 interface, and the serial ports 0, 1, 2 and 3 are further expanded into one-way RS485 interface. The expanded serial ports can also adopt other conventional forms.

[0030] As shown in Figure 6 , the level control chip adopts STC8G1K17 chip, which further expands the serial port 7 into one-way level control circuit, outputs four-way level control signals, and controls the opening and closing of four-way relays.

[0031] The principle of the circuit is: the MCU sends control signals to the USB-to-8 serial port chip CH348, the USB-to-8 serial port chip is used to expand one USB port into 8 USB ports, the USB-to-8 serial port chip realizes the conversion between USB signals and 8 serial port TTL level signals; the serial port-to-RS485 and RS232 chip realizes the conversion between serial port TTL level signals and RS485 and RS232 level signals, and the serial port-to-CAN chip realizes the conversion between serial port TTL level signals and CAN communication signals; the serial port level control chip is responsible for the conversion between serial port TTL level signals and four-way level control signals, and realizes the driving of external devices.

[0032] It should be noted that in the embodiments provided in the present application, it should be understood that the disclosed technical content can be implemented by other ways. Among them, the above described system embodiments are only schematic, for example, the division of the units can be a logical function division, and actual implementation can have another division mode, for example, a plurality of units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point, the coupling or direct coupling or communication connection between the units or modules shown or discussed can be indirect coupling or communication connection through some interfaces, and can be electrical or other forms.

[0033] The units described as separate components can or can not be physically separate, and the components shown as units can or can not be physical units, that is, they can be located in one place, or they can be distributed to multiple units. Part or all of the units can be selected to achieve the purpose of the embodiment scheme according to actual needs.

[0034] In addition, the function units in each embodiment of the present application can be integrated in one processing unit, or each unit can exist physically, or two or more units can be integrated in one unit. The integrated unit can be realized in the form of hardware.

[0035] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application and not to limit it. Although the present application has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solutions of the present application can be modified or replaced by equivalents without departing from the purpose and scope of the present application, and they should be covered in the scope of the claims of the present application.

Claims

1. A USB interface based serial communication conversion circuit, characterized in that, The circuit comprises one USB-to-8 serial port chip, two serial port-to-CAN chips, one serial port-to-RS232 chip, four serial port-to-RS485 chips and one level control chip; the uplink port of the USB-to-8 serial port chip is connected with the USB interface of the microprocessor; the downlink port of the USB-to-8 serial port chip is connected with each serial port conversion chip and the level control chip, for expanding the USB port into two CAN communication interfaces, one 232 communication interface, four 485 communication interfaces and one level control circuit; the level control chip outputs four level control interfaces and is connected with four relays respectively, for controlling the opening and closing of the four relays.

2. The USB interface-based serial communication conversion circuit according to claim 1, characterized in that, The USB-to-8 serial port chip adopts a CH348 chip.

3. The USB interface-based serial communication conversion circuit according to claim 2, characterized in that, The microprocessor adopts an STM32X processing chip.

4. The USB interface-based serial communication conversion circuit according to claim 3, characterized in that, The 42th pin and the 43th pin of the CH348 chip are connected with the USB interface of the microprocessor.

5. The USB interface based serial communication conversion circuit according to claim 1, wherein, The serial port-to-CAN chip adopts a MCP2542FD-H / SN chip.

6. The USB interface based serial communication conversion circuit according to claim 1, wherein, The serial port-to-RS232 chip adopts a MAX3232ID chip.

7. The USB interface based serial communication conversion circuit according to claim 1, wherein, The serial port-to-RS485 chip adopts a MAX345ESA chip.

8. The USB interface based serial communication conversion circuit according to claim 1, wherein, The level control chip adopts a STC8G1K17 chip.

Images