A CAN-serial communication conversion device

Abstract

The application provides a CAN-serial port communication conversion device, which mainly comprises six parts of a DSP control circuit, a CAN interface driving circuit, a serial port interface driving circuit, an external storage circuit, a crystal oscillator circuit and a power supply circuit. The local CAN bus network using the CAN-serial port communication conversion device and the interrupt equipment with the 422 serial port can realize data transmission of the CAN-422 protocol. There are two working data frames and two interface parameter configuration frames. The working data frame is divided into a serial port data frame and a CAN data frame (standard frame or extended frame according to interface configuration), and the interface parameter configuration frame is divided into a general parameter configuration frame and an emergency parameter configuration frame. The operation process of the CAN-serial port communication conversion device mainly comprises a BOOT program segment, an application program segment and the jump from the BOOT program segment to the application program segment at a fixed time, and the CAN-serial port communication conversion device finally runs in the application program segment.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of fieldbus technology, and particularly relates to a CAN-serial port communication conversion device. BACKGROUND

[0002] The controller area network (CAN) is widely applied in radar systems at present due to its advantages of reliable communication, network broadcast, simple cable layout and wiring, and is particularly suitable for distributed network of various terminal sensors in the system. However, various terminal sensors in the system have the characteristics of multiple types and multiple interfaces, some terminal sensors cannot be directly connected to the CAN bus network, and do not have a separate uplink and downlink data communication link, so the problem of connecting the terminal sensors to the CAN bus network and realizing the last mile of data uplink and downlink needs to be solved. SUMMARY

[0003] Therefore, the application provides a CAN-serial port communication conversion device, which realizes CAN-422 serial port communication protocol transmission, solves the problem of connecting serial port equipment to the CAN bus network and networking the last mile.

[0004] The CAN-serial port communication conversion device comprises a DSP control circuit, a CAN interface driving circuit, a serial port interface driving circuit, an external storage circuit, a crystal oscillator circuit and a power supply circuit. The DSP control circuit is the central part of data processing and control of the device, relies on the CAN interface driving circuit and the serial port interface driving circuit, realizes receiving, interrupting and data analyzing of the CAN interface and the serial port interface, and sends data after CAN-serial port protocol conversion according to the specified protocol. Interface configuration parameters are stored in the external storage circuit, and are read and configured after the device is powered on. The DSP chip internally provides a cache area for receiving data.

[0005] The technical principle mainly comprises four parts. The first part is the basic working principle of the CAN-serial port communication conversion device. The second part is the application topology of the CAN-serial port communication conversion device. The third part is the basic protocol framework of the CAN-serial port communication conversion device. The fourth part is the parameter configuration interface and storage of the CAN-serial port communication conversion device.

[0006] The basic working principle of the CAN-serial communication conversion device is that the CAN-serial communication conversion device has one CAN bus interface and one 422 serial port, the serial port transmits and receives data according to a predetermined communication protocol format, the data area data contained in the serial port data are consistent with the CAN interface data transmission and reception. The CAN communication parameters and the serial communication parameters of the CAN-serial communication conversion device can be configured through a parameter configuration interface, and the configuration parameters can be stored. The CAN-serial communication conversion device adopts a transparent transmission mode and does not process and change the CAN communication data area information, so as to ensure the completeness and originality of the data. At the same time, the CAN interface and the serial port of the CAN-serial communication conversion device have data buffering, which can ensure the real-time response of the interface and the integrity of the data frame.

[0007] The application topology of the CAN-serial communication conversion device is that as a bridging device between a terminal serial port device and a CAN bus network, the CAN-serial communication conversion device realizes data interaction with the terminal serial port device through the serial port and realizes network connection with the CAN bus network through the CAN interface. The CAN interface side of the CAN-serial communication conversion device is connected to the CAN bus network and meets the bus topology requirements, and no matching impedance is provided in the device.

[0008] The basic protocol framework of the CAN-serial communication conversion device is that the CAN-serial communication conversion device defines a serial communication frame, a CAN interface communication frame and a parameter configuration frame. The serial communication frame includes a frame header area, a frame length area, a frame data area (containing 4-byte ID information and 8-byte data information), a frame check area and a frame tail area. The CAN interface communication frame meets the CAN bus technical specification (Version 2.0). The parameter configuration frame is divided into two types, one is a normal configuration frame configured through serial communication in a normal working state, and the other is an emergency configuration frame configured through a CAN interface in a BOOT state, which is used when the serial port parameters and the CAN interface parameters are unknown.

[0009] The parameter configuration interface and storage of the CAN-serial communication conversion device can be realized through serial communication or CAN interface communication according to the specified protocol. The configuration parameters are stored in the EEPROM to realize power failure storage, and the CAN-serial communication conversion device reads the EEPROM configuration parameters after the BOOT state ends in 10 seconds to complete the parameter configuration operation of the CAN interface and the serial port. The configuration parameters include the CAN communication frame type, the baud rate, the serial communication baud rate, the data bit, the stop bit and the check bit.

[0010] The beneficial effects of the present application are

[0011] This solves the "last mile" problem of connecting serial devices to the CAN bus network and forming a network, avoiding the need to build separate data uplink and downlink links for individual devices, and reducing the complexity and cost of the system data network. Attached Figure Description

[0012] Figure 1 This is a block diagram of the CAN-serial communication conversion device.

[0013] Figure 2 This is a schematic diagram of the application topology of a CAN-serial communication conversion device.

[0014] Figure 3 This is a schematic diagram of the protocol frame of a CAN-serial communication conversion device.

[0015] Figure 4 This is a flowchart of the operation of the CAN-serial communication conversion device. Detailed Implementation

[0016] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] like Figure 1 As shown, the hardware of this invention mainly consists of six parts: a DSP control circuit, a CAN interface driver circuit, a serial port interface driver circuit, an external storage circuit, a crystal oscillator circuit, and a power supply circuit. The DSP control circuit is the central part for data processing and control of the device. Relying on the CAN interface driver circuit and the serial port interface driver circuit, it parses the received interrupt data from the CAN interface and the serial port interface, and transmits the data after CAN-serial protocol conversion according to the specified protocol. The device's interface configuration parameters are stored in an external storage chip, which is read and configured after the device is powered on. The DSP chip internally provides a buffer area for received data.

[0018] like Figure 2 As shown, in a distributed CAN local area network topology, some terminal devices, lacking a CAN interface and only having a serial port, cannot access the CAN local area network and therefore cannot achieve normal data uplink and downlink transmission. Furthermore, creating separate data uplink and downlink channels for these terminal devices is not feasible from both a rationale and economic perspective. Interrupt devices with serial ports are interconnected with the CAN-serial communication conversion device via the serial port. The CAN-serial communication conversion device then accesses the CAN local area network through its own CAN interface, enabling transparent CAN-serial data transmission.

[0019] like Figure 3As shown, the CAN-serial communication conversion device mainly contains 4 types of frame protocols, 2 types of working data frames, and 2 types of interface parameter configuration frames. Among them, the working data frame is divided into a serial port data frame and a CAN data frame (according to the interface configuration, it is a standard frame or an extended frame), and the interface parameter configuration frame is divided into a general parameter configuration frame and an emergency parameter configuration frame. The general parameter configuration frame is realized through the serial port of the CAN-serial communication conversion device, and the emergency parameter configuration frame is realized through the CAN interface of the CAN-serial communication conversion device. The emergency parameter configuration frame is mainly used in the case that the current serial port parameters of the CAN-serial communication conversion device cannot be confirmed and the serial port communication cannot be established, and the CAN interface is communicated by default through the BOOT program to realize the modification of the interface parameters of the CAN-serial communication conversion device.

[0020] As shown in the figure, Figure 4 After the CAN-serial communication conversion device is powered on, it starts first, enters the BOOT program, and the program runs for about 10s. During this period, the CAN-serial communication conversion device can receive the emergency parameter configuration frame, and the emergency parameter configuration frame is an extended frame with a frame ID of 0x00000010. If the emergency parameter configuration frame is received during the BOOT program running period, the CAN-serial communication conversion device stores the device interface configuration parameters into the EEPROM after analyzing the frame, and if the emergency parameter configuration frame is not received, the CAN-serial communication conversion device waits for the end of the BOOT program (about 10s) running. After the BOOT program running is finished, the CAN-serial communication conversion device will automatically jump to the application program entrance of the CAN-serial communication conversion device, and thereafter the CAN-serial communication conversion device will always run in the application program until the device is powered off. The CAN-serial communication conversion device in the application program running state monitors the received interrupt in real time, analyzes the data frames received by the CAN interrupt or the serial port interrupt, and converts and sends the data to the outside through the serial port or the CAN interface according to the CAN-serial communication protocol. During this process, if the device serial port receives the general parameter configuration frame during this process, the configuration parameters are analyzed and stored in the external storage chip according to the protocol. The configuration parameters will be called when the device is powered on next time, and the initialization work of the device interface will be completed.

[0021] The present application is not limited to the above specific embodiments, and various modifications and changes can be made to the present application. Any modification, equivalent replacement, improvement, etc. made to the above embodiments according to the technical essence of the present application should be included in the protection scope of the present application.

Claims

1. A CAN-serial communication conversion device, characterized in that: It comprises a DSP control circuit, a CAN interface driving circuit, a serial interface driving circuit, an external storage circuit, a crystal oscillator circuit and a power supply circuit; the DSP control circuit is the central part of device data processing and control, relying on the CAN interface driving circuit and the serial interface driving circuit, to realize the reception, interruption and data analysis of the CAN interface and the serial interface, and to send data after CAN-serial protocol conversion according to the specified protocol; The interface configuration parameters are stored in the external storage circuit and read and configured after the device is powered on; the DSP chip internally provides a cache area for receiving data; The CAN-serial communication conversion device defines serial communication frames, CAN interface communication frames and parameter configuration frames; The serial communication frame comprises a frame header area, a frame length area, a frame data area, a frame check area and a frame tail area; the CAN interface communication frame conforms to the CAN bus communication specification; the parameter configuration frame is divided into two types, one is a general configuration frame configured through serial communication in the normal working state, and the second is an emergency configuration frame configured through the CAN interface in the BOOT state; The working data frame is divided into a serial data frame and a CAN data frame, and the interface parameter configuration frame is divided into a general parameter configuration frame and an emergency parameter configuration frame; the general parameter configuration frame is realized through the serial port of the CAN-serial communication conversion device, and the emergency parameter configuration frame is realized through the CAN interface of the CAN-serial communication conversion device; the emergency parameter configuration frame is mainly used in the case that the current serial port parameters of the CAN-serial communication conversion device cannot be confirmed and serial communication cannot be established, and is communicated through the default CAN interface of the BOOT program to realize the modification of the interface parameters of the CAN-serial communication conversion device.

2. The CAN-serial communication conversion device according to claim 1, characterized in that: The CAN-serial communication conversion device has one CAN bus interface and one 422 serial port, and transmits and receives data in accordance with the established communication protocol format; the data area data contained in the serial data is consistent with the CAN interface data; the CAN-serial communication conversion device adopts a transparent transmission mode and does not process or change the CAN communication data area information, so as to ensure the completeness and originality of the data; meanwhile, the CAN interface and the serial port of the CAN-serial communication conversion device both have data buffering, which can ensure the real-time response of the interface and the integrity of the data frame.

3. The CAN-serial communication conversion device according to claim 2, characterized in that: The CAN-serial communication conversion device realizes data interaction with the terminal serial port equipment through the serial port and realizes network connection with the CAN bus network through the CAN interface; the CAN interface side of the CAN-serial communication conversion device is connected to the CAN bus network and meets the bus topology requirements without matching impedance in the device.

4. The CAN-serial communication conversion device according to claim 1, characterized in that: The configuration parameters of the CAN-serial communication conversion device are stored in the external storage circuit to realize power failure storage; after the BOOT state ends in 10 seconds, the CAN-serial communication conversion device reads the configuration parameters of the external storage circuit to complete the parameter configuration operation of the CAN interface and the serial port; the configuration parameters include the CAN communication frame type, the baud rate, the serial communication baud rate, the data bit, the stop bit and the check bit.

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