CN203933666U

CN203933666U - A kind of CAN bus repeater

Info

Publication number: CN203933666U
Application number: CN201420225762.7U
Authority: CN
Inventors: 胡啸鹰
Original assignee: SHANGHAI ZESSEN INDUSTRIAL Co Ltd
Current assignee: SHANGHAI ZESSEN INDUSTRIAL Co Ltd
Priority date: 2014-05-05
Filing date: 2014-05-05
Publication date: 2014-11-05
Anticipated expiration: 2024-05-05

Abstract

A kind of CAN bus repeater of the present utility model, comprise single-chip microcomputer, power module and two groups of CAN bus communication circuits, single-chip microcomputer is connected with CAN controller, in order to two groups of CAN bus communication circuits are managed and to be monitored, realize the forwarding of two-way CAN channel data, by independent current source, power and photoisolator, two groups of each parts of CAN bus communication circuit and chip microcontroller be electrical isolation completely, can suppress electromagnetic interference, protection system circuit is not subject to web influence, protection system circuit is not subject to web influence, greatly improved the possibility that system is used in adverse circumstances, single-chip microcomputer is connected with exented memory, as hardware buffer, when data traffic is large, do not lose frame, do not stop up, meet the needs of long distance transmit.

Description

A kind of CAN bus repeater

Technical field

The utility model relates to technique of computer measurement and control field, particularly a kind of CAN bus repeater.

Background technology

CAN (controller local area network) is one of most widely used fieldbus in the world, CAN is a kind of serial communication bus of how self-service mode, and Basic Design code requirement has very high bit rate, high resistance electromagnetic interference and can detect any mistake.CAN bus can increase arbitrarily dielectric, need not change hardware setting.CAN bus the maximum data transmission rate can reach 1Mbit/s (communication distance 40m).This makes to control and become very easy in real time.When reaching 10km, signal transmission distance still can provide the message transmission rate up to 5Kbit/s.It has can articulate that many, the total line use ratios of node are high, mistake is processed and error-detection mechanism is reliable, information that send can be retransmitted after being destroyed automatically, node automatically exits the outstanding advantages such as bus in the situation that mistake is serious.Because CAN bus has very high real-time performance, it is used widely in the fields such as auto industry, aircraft industry, Industry Control and security protection.CAN bus is microprocessor localized network ripe, the most rising in field bus technique.

Advantage based on above-mentioned CAN bus, in the middle of environmental ecology supervisory control system, utilizes CAN bus hub can realize the transmission of Real-time Monitoring Data.In the middle of practical application, the project demand of environmental ecology supervisory control system height very, comprise automatic monitoring and control appliance that 4 covers are different, each equipment has CAN bus interface, between equipment, need mutual communication, also need Monitoring Data to be real-time transmitted to system control end server by CAN bus, communications distance has reached 1100 meters simultaneously.In the middle of research, long cable cannot be communicated by letter with control end server Venus with the traffic rate of 50kbit/s in the early stage of the project.And because communication data flow is larger, should not reduce again baud rate transmission, in order to strengthen the reliability of CAN bus communication distance and raising transfer of data, need to existing CAN bus repeater further be designed and be improved.

Utility model content

In order to solve the problems of the technologies described above, the purpose of this utility model is to provide CAN bus repeater, can access multichannel data input source, meets the needs of long distance C AN bus communication.

For achieving the above object, the technical solution of the utility model is as follows:

A kind of CAN bus repeater, comprise single-chip microcomputer, power module and two groups of CAN bus communication circuits, every group of CAN bus communication circuit comprises CAN transceiver, photoisolator and CAN controller, the data input pin of described CAN transceiver is connected with data output end with the data input pin of CAN controller after photoisolator with output, single-chip microcomputer is connected with CAN controller, in order to two groups of CAN bus communication circuits are managed and to be monitored, described power module is respectively to the CAN transceiver in single-chip microcomputer and two groups of CAN bus communication circuits, photoisolator and CAN controller carry out independently-powered.

Further, described single-chip microcomputer comprises several I/O interfaces, and single-chip microcomputer is connected with CAN controller by I/O interface, and each I/O mouth is all connected with current-limiting resistance, and current-limiting resistance connects LED light.

Further, described single-chip microcomputer is also connected with exented memory, and extended memory address and I/O interface shine upon one by one, and single-chip microcomputer is accessed I/O interface by exented memory.

Further, described single-chip microcomputer is also connected with baud rate toggle switch, and baud rate toggle switch is connected with resistance, and resistance is connected with CAN controller.

Further, described CAN controller stores several baud rate preset values, and the dial-up value of described baud rate toggle switch is in several baud rate preset values.

Further, described single-chip microcomputer is also connected with RS232 module, and RS232 module provides interface for computer monitoring repeater operation state.

Beneficial effect

1. a kind of CAN bus repeater of the present utility model has two groups of CAN bus communication circuits, realizes the forwarding of two-way CAN channel data.

2. by independent current source, power and photoisolator; two groups of each parts of CAN bus communication circuit and chip microcontroller be electrical isolation completely; can suppress electromagnetic interference, protection system circuit is not subject to web influence, has greatly improved the possibility that system is used in adverse circumstances.

3. single-chip microcomputer is connected with exented memory, as hardware buffer, guarantees when data traffic is large, does not lose frame, does not stop up.

4. the traffic rate of liang group CAN bus communication circuit is adjustable separately, the CAN network of two different communication speeds can be connected.

5.LED indicator light has system operation, bus transmitting-receiving and dislocation state-indicating function.

Accompanying drawing explanation

Fig. 1 is the system architecture diagram of a kind of CAN bus repeater of the utility model;

Fig. 2 is the schematic diagram that this practical CAN controller access exented memory carries out exchanges data.

Embodiment

Below in conjunction with the accompanying drawing in the utility model embodiment, the technical scheme in the utility model embodiment is clearly and completely described, obviously, described embodiment is only the utility model part embodiment, rather than whole embodiment.Embodiment based in the utility model, those of ordinary skills are not making the every other embodiment obtaining under creative work prerequisite, all belong to the scope of the utility model protection.

As shown in Figure 1, the schematic diagram of Fig. 1 a kind of CAN bus repeater of the present utility model.

A CAN bus repeater, comprises single-chip microcomputer 11, power module 40 and two groups of CAN bus communication circuits 20,30.The operation of two groups of CAN bus communication circuits 20,30 is controlled and monitored to single-chip microcomputer 11, and single-chip microcomputer 11 is connected with the read-write internal memory 11 of external high speed, first group of CAN bus communication circuit 20 comprises CAN controller 21, optical coupling isolator 22 and CAN transceiver 23, second group of CAN bus communication circuit 30 comprises CAN controller 31, optical coupling isolator 32 and CAN transceiver 33, power supply mould, 40 carry out independently-powered to single-chip microcomputer 11, CAN controller 21, CAN controller 31, optical coupling isolator 22, optical coupling isolator 32, CAN transceiver 23 and CAN transceiver 33 respectively.

As a preferred embodiment, a kind of CAN bus repeater of the present utility model adopts the high-performance microcontroller C8051F021 of Laboratories company as the main control unit of single-chip microcomputer 11.C8051F021 has the CIP-51 microcontroller kernel completely compatible with 8051 cores of Intel, is complete mixed signal SoC chip.It adopts high-speed flow line structure, and be 1～2 clock cycle time for each instruction, has the SRAM of 64KB flash memory able to programme and 4KB.C8051F021 has the I/O interface on maximum 22 tunnels, adopts interrupt mode to be connected with CAN controller 21,31.

For meeting large, the explosive strong feature of communication data total amount of two groups of CAN bus communication circuits 20,30, the concussion frequency of C8051F021 adopts 22.1184MHZ to improve the speed of service.Simultaneously in order to relax the frame information of two CAN bus communication circuit 20,30 sending and receivings, C8051F021 has expanded the read-write exented memory 12 of a slice 32KB/12ns, the input/output space address realm that it takies is 0x0000～0x7FFF, the data that transmit for reading CAN controller 21,31.

C8051F021 has 5 I/O ports as the state indication of two CAN transceiver 23,33 ports, each I/O port meets a LED by current-limiting resistance, be used to refer to the operating state of two CAN controllers 23,33, when sending, receiving in data or occurring mistake, the glittering warning of LED meeting, is convenient to user and understands the operating state of CAN controller 21,31 and carry out failure diagnosis.C8051F021 also has 8 10 ADC analog input channel AIN0～AIN7 and is used as Configuration of baud rate switch 13.The reference voltage source of A/D adopts internal reference voltage 2.43V, and when the input voltage <0.5V of passage, the input of program judgement switching value is 0; Otherwise when input voltage is between 0.5V and 2.43V, program judgement is 1.The magnitude of voltage of each input channel is determined jointly by dividing potential drop, pull-up resistor and toggle switch 13.One of 16 preset values in the corresponding CAN transceiver of 4 binary values 23, the 33 port communication speed (5K～1Mbps) of toggle switch 13.The communication speed of two CAN transceiver 23,33 ports can be arranged to different values, but consistent with external CAN communication equipment.

CAN controller 21,31 adopts the CAN SJA1000Controler of Philips company.It can work under BasocCAN pattern or PeliCAN pattern, is directly connected with the single-chip microcomputer 11 of 8051 cores of Intel.SJA1000 has the reception buffer of 64 bytes, supports 11 and 29 ID, hot-swappable, supports CAN2.0B agreement, only relies on CAN controller 21,31 hardware circuits own just can realize tissue and the transmission of communication frames.

As shown in Figure 2, the access of 11 pairs of CAN controllers of single-chip microcomputer 21,31 realizes by exented memory, the I/O address of two CAN controllers 21,31 is mapped with corresponding address realm at exented memory 12 respectively, is respectively the data buffer zone 121,122 that 0x8000～0xBFFF communicates by letter as two CAN bus datas with 0xC000～0xFFFF.CAN controller 21 sends and CAN controller 31 territories, reception buffer zone, physically should belong to an address realm, shares a data buffer zone 121.In like manner, CAN controller 31 sends and CAN controller 21 territories, reception buffer zone, physically should belong to an address realm, shares a data buffer zone 122.Its data retransmission mechanism is as follows: if the CAN bus of A side to single-chip microcomputer 11 transmission data, after the CAN controller 21 of A side is received Frame, single-chip microcomputer 11 deposits Frame in the data buffer zone of exented memory 121; When program detects buffering area 121 not for sky, the CAN controller 31 to B side sends the Frame that A side joints are received, send finger adds 1, and now, the port of CAN transceiver 33 just should receive auspicious that CAN transceiver port 23 forwards.

In order to improve data processing real-time, single-chip microcomputer 11 is taked interrupt mode communication with CAN controller 21,31, and the interrupt output of two CAN controllers 21,31 connects respectively INT0 and the INT1 interface of single-chip microcomputer 11.CAN controller 21,31 has baud rate register, and in order to store the different communication speeds that arrange of CAN transceiver 23,33, baud rate register adopts the crystal oscillator of 16MHz.The hardware reset pin of CAN controller 21,31 is controlled by an I/O mouth of single-chip microcomputer 11, and CAN controller 21,31 resets during for low level.For assurance system can reliably working, and improve interference performance, CAN controller 21,31 by after the isolation of high speed photo coupling isolator 22,32 with 23,33 communications of CAN transceiver.It should be noted that the 5V power supply 40 that the optical coupling isolator 22,32 of two groups of CAN bus communication circuits adopts must isolate completely with the 5V power supply 40 of CAN controller 21,31 and single-chip microcomputer 11, two CAN transceivers 23,33 are also used different insulating power supply 40, otherwise adopt optical coupling isolator 22,32 also just to lose meaning.

CAN transceiver 23,3 adopts the TJA1040 of PHILIPS company.TJA1040 is the interface chip between CAN controller 21,31 and physical bus, and speed can reach 1Mbps.TJA1040 provides two groups of differential sending and receiving functions for CAN bus communication circuit.Between the pin CANL of TJA1040 and CANH, increased a single order RC low pass filter, to suppress high-frequency interferencing signal, also the connected recovery certainly insurance of a 50mA of RC low pass filter, the spike on can valid bus.CAN transceiver 23,33 is also connected with the terminal resistance of 120 Ω, and terminal resistance is provided with a wire jumper, and user can utilize wire jumper to determine whether to enable terminal resistance according to actual needs.

In order to debug conveniently, 11 UART0 interface of single-chip microcomputer is also connected with MAX3232 chip 14, is connected with the PC RS232 port of control end, monitors the operating state of CAN bus repeater, if any abnormality generation, will send relevant information to computer.

The foregoing is only preferred embodiment of the present utility model; not in order to limit the utility model; all within spirit of the present utility model and principle, any modification of doing, be equal to replacement, improvement etc., within all should being included in protection range of the present utility model.

Claims

1. a CAN bus repeater, it is characterized in that, comprise single-chip microcomputer, power module and two groups of CAN bus communication circuits, every group of CAN bus communication circuit comprises CAN transceiver, photoisolator and CAN controller, the data input pin of described CAN transceiver is connected with data output end with the data input pin of CAN controller after photoisolator with output, single-chip microcomputer is connected with CAN controller, in order to two groups of CAN bus communication circuits are managed and to be monitored, described power module is respectively to the CAN transceiver in single-chip microcomputer and two groups of CAN bus communication circuits, photoisolator and CAN controller carry out independently-powered.

2. a kind of CAN bus repeater according to claim 1, is characterized in that, described single-chip microcomputer comprises several I/O interfaces, and single-chip microcomputer is connected with CAN controller by I/O interface, and each I/O mouth is all connected with current-limiting resistance, and current-limiting resistance connects LED light.

3. a kind of CAN bus repeater according to claim 2, is characterized in that, described single-chip microcomputer is also connected with exented memory, and extended memory address and I/O interface shine upon one by one, and single-chip microcomputer is accessed I/O interface by exented memory.

4. a kind of CAN bus repeater according to claim 1, is characterized in that, described single-chip microcomputer is also connected with baud rate toggle switch, and baud rate toggle switch is connected with resistance, and resistance is connected with CAN controller.

5. a kind of CAN bus repeater according to claim 4, is characterized in that, described CAN controller stores several baud rate preset values, and the dial-up value of described baud rate toggle switch is in several baud rate preset values.

6. a kind of CAN bus repeater according to claim 1, is characterized in that, described single-chip microcomputer is also connected with RS232 module, and RS232 module provides interface for computer monitoring repeater operation state.