CAN-serial port communication conversion device

Abstract

The invention provides a CAN-serial port communication conversion device which is mainly composed 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. Data transparent transmission of a CAN (Controller Area Network)-422 protocol can be realized by using a local CAN bus network of the CAN-serial port communication conversion device and interruption equipment with a 422 serial port. There are two working data frames and two interface parameter configuration frames. Wherein the working data frame is divided into a serial port data frame and a CAN (Controller Area Network) data frame (configured as a standard frame or an extended frame according to an interface), and the interface parameter configuration frame is divided into a general parameter configuration frame and an emergency parameter configuration frame. The running process of the CAN-serial communication conversion device is mainly formed by the BOOT program segment, the application program segment and the jump from the BOOT program segment to the application program segment in a timing mode, and the CAN-serial communication conversion device finally runs in the application program segment.

Description

Technical Field

[0001] The invention belongs to the technical field of field bus, and in particular relates to a CAN-serial communication conversion device. Background Art

[0002] Controller Area Network (CAN) is currently widely used in radar systems due to its advantages of reliable communication, network broadcasting, and simple cable layout and wiring. It is especially suitable for distributed networking of various terminal sensors in the system. However, various terminal sensors in the system are characterized by many types and interfaces. Some terminal sensors cannot be directly connected to the CAN bus network, and do not have a separate communication link for uplink and downlink data. Therefore, it is necessary to solve the "last mile" problem of connecting such terminal sensors to the CAN bus network and realizing data uplink and downlink. Summary of the invention

[0003] To this end, the present invention proposes a CAN-serial communication conversion device to achieve transparent transmission of the CAN-422 serial communication protocol and solve the "last meter" problem of serial port devices accessing the CAN bus network and networking.

[0004] A CAN-serial communication conversion device of the present invention comprises a DSP control circuit, a CAN interface drive circuit, a serial interface drive circuit, an external storage circuit, a crystal oscillator circuit and a power supply circuit; the DSP control circuit is the central part of the device data processing and control, relying on the CAN interface drive circuit and the serial interface drive circuit to realize the reception, interruption and data analysis of the CAN interface and the serial interface, and send data after CAN-serial protocol conversion according to the prescribed protocol; the interface configuration parameters are stored in the external storage circuit, and are read and configured after the device is powered on; a cache area for receiving data is provided inside the DSP chip.

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

[0006] The basic working principle of the CAN-serial communication conversion device: The external interface of the CAN-serial communication conversion device has a CAN bus interface and a 422 serial port. The serial port sends and receives data in accordance with the established communication protocol format. The data area data contained in the serial port data is consistent with the data sent and received by the CAN interface. The CAN communication parameters and serial communication parameters of the CAN-serial communication conversion device can be configured through the parameter configuration interface, and the configuration parameters can be stored. The CAN-serial communication conversion device adopts a transparent transmission method and does not process or change the CAN communication data area information to ensure the completeness and originality of the data. At the same time, the CAN interface receiving data and the serial port receiving data 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] Application topology of CAN-serial communication conversion device: As a bridge device between terminal serial port equipment and CAN bus network, CAN-serial communication conversion device realizes data interaction with terminal serial port equipment through serial port, and realizes network connection with CAN bus network through CAN interface. The CAN interface side of CAN-serial communication conversion device is connected to CAN bus network, which meets the bus topology requirements and does not need matching impedance in the device.

[0008] CAN-serial communication conversion device basic protocol framework: CAN-serial communication conversion device customizes serial communication frame, CAN interface communication frame and parameter configuration frame. The serial communication frame contains frame header area, frame length area, frame data area (including 4 bytes of ID information and 8 bytes of data information), frame check area and frame tail area. The CAN interface communication frame complies with the CAN bus technical specification (Version 2.0). There are two types of parameter configuration frames, one is a normal configuration frame configured through serial communication under normal working conditions, the second is an emergency configuration frame configured through the CAN interface in the BOOT state, and the second is used when the serial port parameters and CAN interface parameters are unknown.

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

[0010] The beneficial effects of the present invention are

[0011] Solve the "last mile" problem of serial port devices accessing the CAN bus network and networking, avoid building data uplink and downlink links separately for individual devices, and reduce the complexity and cost of the system data network. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

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

[0015] Figure 4 This is the operation flow chart of the CAN-serial communication conversion device. DETAILED DESCRIPTION

[0016] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0017] like Figure 1 As shown, the hardware of the present invention is mainly composed of six parts: DSP control circuit, CAN interface drive circuit, serial port interface drive circuit, external storage circuit, crystal oscillator circuit and power supply circuit. The DSP control circuit is the central part of the device data processing and control. Relying on the CAN interface drive circuit and the serial port interface drive circuit, it realizes the analysis of the received interrupt data of the CAN interface and the serial port interface, and sends the data after the CAN-serial port protocol conversion according to the prescribed protocol. The interface configuration parameters of the device are stored in the external storage chip, which are read and configured after the device is powered on. The DSP chip provides a cache area for received data.

[0018] like Figure 2 As shown in the figure, in the distributed CAN local area network topology, some terminal devices cannot access the CAN local area network because they only have serial ports but no CAN interfaces, and cannot realize data uplink and downlink normally. In addition, it is not advisable to create separate data uplink and downlink channels for these terminal devices from the perspective of solution rationality and economy. The interrupt device with a serial port is interconnected with the CAN-serial communication conversion device through the serial port, and the CAN-serial communication conversion device is connected to the CAN local area network through its own CAN interface to realize CAN-serial data transparent transmission.

[0019] like Figure 3As shown, the CAN-serial communication conversion device mainly includes 4 types of frame protocols, 2 working data frames, and 2 interface parameter configuration frames. Among them, the working data frame is divided into a serial data frame and a CAN data frame (based on the interface configuration as 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 implemented through the serial port of the CAN-serial communication conversion device, and the emergency parameter configuration frame is implemented through the CAN interface of the CAN-serial communication conversion device. The emergency parameter configuration frame is mainly used when the serial port parameters of the current CAN-serial communication conversion device cannot be confirmed and serial communication cannot be established. It communicates through the CAN interface configured by the default of the BOOT program to realize the modification of the interface parameters of the CAN-serial communication conversion device.

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

[0021] The present invention is not limited to the above specific implementations, and the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made to the above implementations based on the technical essence of the present invention shall be included in the protection scope of the present invention.

Claims

1. A CAN-serial communication conversion device, characterized in that: It includes DSP control circuit, CAN interface drive circuit, serial port interface drive circuit, external storage circuit, crystal oscillator circuit and power supply circuit; DSP control circuit is the central part of device data processing and control, relying on CAN interface drive circuit and serial port interface drive circuit to realize CAN interface and serial port interface reception, interruption and data analysis, and send data after CAN-serial port protocol conversion according to the prescribed protocol; The interface configuration parameters are stored in an external storage circuit and are read and configured after the device is powered on; The DSP chip provides a buffer area for receiving data.

2. A CAN-serial communication conversion device according to claim 1, characterized in that: The external interface of the CAN-serial communication conversion device has one CAN bus interface and one 422 serial port. The serial port sends and receives data in accordance with the established communication protocol format. The data area data contained in the serial port data is consistent with the data sent and received by the CAN interface. The CAN-serial communication conversion device adopts a transparent transmission method and does not process or change the CAN communication data area information to ensure the completeness and originality of the data. At the same time, the CAN interface receiving data and the serial port receiving data 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.

3. A 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 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, which meets the bus topology requirements and does not require matching impedance in the device.

4. A CAN-serial communication conversion device according to claim 3, characterized in that: The CAN-serial communication conversion device customizes the serial communication frame, CAN interface communication frame and parameter configuration frame; the serial communication frame includes 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 complies with the CAN bus communication specification; the parameter configuration frame is divided into two types, one is a normal configuration frame configured through serial communication under normal working conditions, and the second is an emergency configuration frame configured through the CAN interface in the BOOT state.

5. A CAN-serial communication conversion device according to claim 4, characterized in that: The configuration parameters of the CAN-serial communication conversion device are stored in the external storage circuit to realize power-off 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, baud rate, serial communication baud rate, data bit, stop bit and check bit.

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