WO2022040997A1

WO2022040997A1 - Intra-board communication circuit and intra-board communication device

Info

Publication number: WO2022040997A1
Application number: PCT/CN2020/111503
Authority: WO
Inventors: 刘鹏飞; 唐弘扬; 刘晓红; 邓家勇; 吴壬华
Original assignee: 深圳欣锐科技股份有限公司
Priority date: 2020-08-26
Filing date: 2020-08-26
Publication date: 2022-03-03
Also published as: CN113168145B; CN113168145A

Abstract

Disclosed in embodiments of the present application are an intra-board communication circuit and an intra-board communication device. The intra-board communication circuit comprises a first diode, a second diode, a first resistor, a second resistor, and an isolation chip. The intra-board communication device comprises a first communication node, a second communication node, and the intra-board communication circuit. By implementing the embodiments of the present application, CAN communication between communication nodes can be achieved in a board, without using a CAN transceiver, thereby reducing the hardware cost.

Description

In-board communication circuit and in-board communication device

technical field

The present application relates to the technical field of electronic circuits, and in particular, to an intra-board communication circuit and an intra-board communication device.

Background technique

The controller area network (CAN) bus is a multi-master bus, that is, each node machine can become the master, and the node machines can also communicate. CAN communication is widely used in automotive, medical, marine, aviation and other fields due to its excellent performance, unique design and high reliability.

In-board communication generally adopts serial communication interface (SCI), serial peripheral interface (SPI), I2C (inter-integrated circuit, built-in integrated circuit) and other buses, but CAN bus has its own There are some advantages, the use of CAN bus for intra-board communication can make full use of its advantages to realize the communication process in different scenarios. In CAN communication, each communication node sends and receives signals from other communication nodes on the bus through a CAN transceiver. However, when CAN communication is performed on the board or on-chip, adding a CAN transceiver to each communication node on the board or on-chip will increase the hardware cost.

SUMMARY OF THE INVENTION

Embodiments of the present application provide an intra-board communication circuit and an intra-board communication device, which implement CAN communication in the board without using a CAN transceiver, thereby reducing hardware costs.

In a first aspect of the embodiments of the present application, an intra-board communication circuit is provided. The intra-board communication circuit is used to implement intra-board communication between a first communication node and a second communication node, and the intra-board communication circuit includes a first communication node. a diode, a second diode, a first resistor, a second resistor and an isolation chip, wherein:

The transmitting end of the first communication node is connected to the cathode of the first diode, and the anode of the first diode is connected to the receiving end of the first communication node and the first end of the first resistor, The second end of the first resistor is connected to the first power supply end; the transmitting end of the second communication node is connected to the cathode of the second diode, and the anode of the second diode is connected to the second communication node the receiving end of the node and the first end of the second resistor, the second end of the second resistor is connected to the second power supply end;

The transmitting end of the first communication node is connected to the second input end of the isolation chip, the receiving end of the first communication node is connected to the first output end of the isolation chip, and the transmitting end of the second communication node When the first input end of the isolation chip is connected, and the receiving end of the second communication node is connected to the second output end of the isolation chip, if the transmitting end of the first communication node and/or the second The sending end of the communication node is at low level, and the on-board communication circuit realizes that the receiving end of the first communication node and the receiving end of the second communication node are at low level.

Optionally, the in-board communication circuit further includes a third diode and a fourth diode, the anode of the third diode is connected to the receiving end of the first communication node, and the fourth diode is connected to the receiving end of the first communication node. The positive pole of the tube is connected to the receiving end of the second communication node;

The cathode of the third diode is connected to the first output terminal of the isolation chip, the receiving terminal of the first communication node is connected to the second input terminal of the isolation chip, and the cathode of the fourth diode is connected to the first output terminal of the isolation chip. When the second output end of the isolation chip is connected, and the receiving end of the second communication node is connected to the first input end of the isolation chip, if the transmitting end of the first communication node and/or the second communication node The sending end of the communication node is at low level, and the on-board communication circuit realizes that the receiving end of the first communication node and the receiving end of the second communication node are at low level; if the sending end of the first communication node Both the terminal and the transmitting terminal of the second communication node are at a high level, and the on-board communication circuit realizes that the receiving terminal of the first communication node and the receiving terminal of the second communication node are at a high level.

Optionally, the on-board communication circuit further includes a first filter circuit; the first end of the first resistor is connected to the receiving end of the first communication node through the first filter circuit.

Optionally, the first filter circuit includes a third resistor and a first capacitor; the first end of the first capacitor is connected to the first end of the third resistor and the receiving end of the first communication node, so The second end of the first capacitor is connected to the first ground end, and the second end of the third resistor is connected to the first end of the first resistor.

Optionally, the on-board communication circuit further includes a second filter circuit; the first end of the second resistor is connected to the receiving end of the second communication node through the second filter circuit.

Optionally, the second filter circuit includes a fourth resistor and a second capacitor; the first end of the second capacitor is connected to the second end of the fourth resistor and the receiving end of the second communication node, so The second end of the second capacitor is connected to the second ground end, and the first end of the fourth resistor is connected to the first end of the second resistor.

In a second aspect of the embodiments of the present application, an intra-board communication device is provided, and the intra-board communication device includes a first communication node, a second communication node, and any one of the intra-board communication circuits in the first aspect of the embodiments of the present application .

The ground terminal of the first communication node is connected to a third ground terminal, and the ground terminal of the second communication node is connected to a fourth ground terminal, and the third ground terminal is different from the fourth ground terminal.

Wherein, both the first communication node and the second communication node include a microcontroller unit and a CAN controller.

Wherein, optionally, both the first communication node and the second communication node include a micro-control unit, and a CAN controller is integrated in the micro-control unit.

The power supply terminal of the first communication node is connected to the first auxiliary power supply, and the power supply terminal of the second communication node is connected to the second auxiliary power supply.

An embodiment of the present application provides an in-board communication circuit, including a first diode, a second diode, a first resistor, a second resistor and an isolation chip. The in-board communication circuit has a simple structure and adopts electronic components. few. By implementing the embodiments of the present application, the on-board communication circuit can implement the receiving end of the first communication node and the second communication node when the transmitting end of the first communication node or the transmitting end of the second communication node is at a low level. The receiving ends of the communication nodes are all low-level, so that the CAN communication on the board is realized without the CAN transceiver, which not only makes full use of the advantages of CAN communication in the board, but also reduces the hardware cost.

Description of drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the accompanying drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only These are some embodiments of the present application. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings without any creative effort.

1a is a schematic diagram of CAN communication using a CAN transceiver in a traditional method;

Fig. 1b is a kind of CAN signal schematic diagram that adopts CAN transceiver to realize CAN communication disclosed in the embodiment of the present application;

Fig. 1c is a kind of level schematic diagram of the CAN signal that adopts CAN transceiver to realize CAN communication disclosed in the embodiment of the present application;

2a is a schematic structural diagram of an in-board communication circuit disclosed in an embodiment of the present application;

2b is a schematic structural diagram of another on-board communication circuit disclosed in an embodiment of the present application;

3 is a schematic structural diagram of another on-board communication circuit disclosed in an embodiment of the present application;

FIG. 4 is a schematic structural diagram of an in-board communication device disclosed in an embodiment of the present application;

FIG. 5 is a schematic structural diagram of another in-board communication device disclosed in an embodiment of the present application.

detailed description

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are some, but not all, embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the scope of the protection of the present application.

In CAN communication, each communication node sends and receives signals from other communication nodes on the bus through a CAN transceiver. Therefore, each communication node must add a CAN transceiver. In addition, a CAN controller is required to implement CAN communication.

FIG. 1a is a schematic diagram of CAN communication using a CAN transceiver in the conventional method. As shown in Figure 1a, taking the communication node as a microcontroller unit (MCU) as an example, the CAN controller is integrated inside the microcontroller unit MCU. The CAN controller can receive the data sent by the microprocessor in the microcontroller unit MCU, and transmit the data to the CAN transceiver; the CAN transceiver is used to transmit data to the bus or receive data from the bus and transmit it to the CAN controller. However, when CAN communication is implemented on the board, adding a CAN transceiver to each communication node will increase the cost of the on-board communication.

Please refer to FIG. 1 b , FIG. 1 b is a schematic diagram of a CAN signal using a CAN transceiver to realize CAN communication disclosed in an embodiment of the present application. Fig. 1b is a schematic diagram of CAN signals in CAN communication using a CAN transceiver based on Fig. 1a. The CAN signal is a bit stream signal that alternates with dominant level and recessive level. The CAN signal can include transmission control commands, and can also include data segments or data blocks. In the CAN signal, "0" represents dominant, dominant corresponds to low level, "1" represents recessive, and recessive corresponds to high level. As shown in Figure 1b, the CAN signal takes the control command as an example. The CAN signal is the dominant level "0" in the first time period, the recessive level "1" in the second time period, and the third time period. The dominant level is "0" in the time period, the dominant level is "0" in the fourth time period, and the recessive level "1" is in the fifth time period. The sum of the durations is used as a cycle, and the levels corresponding to the five time periods will appear repeatedly in the next cycle, which can be used to periodically transmit the same control command.

Please refer to FIG. 1c. FIG. 1c is a schematic level diagram of a CAN signal that uses a CAN transceiver to implement CAN communication disclosed in an embodiment of the present application. FIG. 1c is a schematic diagram of the level of CAN signals in CAN communication using a CAN transceiver based on FIG. 1a. As shown in Figure 1c, the dominant level and the recessive level in the CAN signal are not voltages corresponding to two specific values, but correspond to two voltage ranges. For example, the dominant level in the CAN signal is "0V~ 1.5V", the corresponding recessive level is "1.5V~5V"; when the dominant level in the CAN signal is "0V~2.5V", the corresponding recessive level is "2.5V~5V"; When the dominant level in the CAN signal is "0V~3.5V", the corresponding recessive level is "3.5V~5V".

The embodiments of the present application provide an intra-board communication circuit and an intra-board communication device, which can implement CAN communication in the board without using a CAN transceiver. A detailed description will be given below.

Please refer to FIG. 2a. FIG. 2a is a schematic structural diagram of an on-board communication circuit disclosed in an embodiment of the present application. As shown in FIG. 2a, the intra-board communication circuit 30 described in this embodiment is used to realize intra-board communication between the first communication node 10 and the second communication node 20, and the intra-board communication circuit includes a first diode D1 , the second diode D2, the first resistor R1, the second resistor R2 and the isolation chip 301, wherein:

The transmitting end TX1 of the first communication node 10 is connected to the cathode of the first diode D1, and the anode of the first diode D1 is connected to the receiving end RX1 of the first communication node 10 and the first diode D1. The first end 11 of the resistor R1 and the second end 12 of the first resistor R1 are connected to the first power supply end; the transmitting end TX2 of the second communication node 20 is connected to the negative electrode of the second diode D2, the The anode of the second diode D2 is connected to the receiving terminal RX2 of the second communication node 20 and the first terminal 21 of the second resistor R2, and the second terminal 22 of the second resistor R2 is connected to the second power terminal;

The transmitting end TX1 of the first communication node 10 is connected to the second input end IN2 of the isolation chip 301 , and the receiving end RX1 of the first communication node 10 is connected to the first output end OUT1 of the isolation chip 301 . When the transmitting end TX2 of the second communication node 20 is connected to the first input end IN1 of the isolation chip 301, and the receiving end RX2 of the second communication node 20 is connected to the second output end OUT2 of the isolation chip 301, If the transmitting end TX1 of the first communication node 10 and/or the transmitting end TX2 of the second communication node 20 is at a low level, the on-board communication circuit 30 implements the receiving end RX1 of the first communication node 10 and the receiving end RX2 of the second communication node 20 is at a low level.

Wherein, the power supply level of the first power supply terminal and the second power supply terminal is the same.

The on-board communication circuit 30 in this embodiment of the present application is suitable for the case where the first communication node 10 , the second communication node 20 and the isolation chip 301 can only output a low level, for example, the first communication node 10 and the second communication node 20 Both the isolation chip 301 and the isolation chip 301 are open collector (Open Collector, OC) gates.

The on-board communication circuit 30 is used for realizing the receiving end RX1 of the first communication node 10 and the second communication node 20 when the transmitting end TX1 of the first communication node 10 and/or the transmitting end TX2 of the second communication node 20 are at low level. The receiving end RX2 of the communication node 20 is all low level;

When the transmitting terminal TX1 of the first communication node 10 is at a low level and the transmitting terminal TX2 of the second communication node 20 is at a low level, the first diode D1 and the second diode in the in-board communication circuit 30 Both the tubes D2 are turned on, and at this time, the receiving end RX1 of the first communication node 10 and the receiving end RX2 of the second communication node 20 are both at low level.

The first communication node 10 and the second communication node 20 can implement controller area network CAN bus communication through the on-board communication circuit 30 . The first communication node 10 and the second communication node 20 can perform data transmission and control command transmission through the on-board communication circuit 30 .

Wherein, the first diode D1 and the second diode D2 may be implemented by using alternative circuits having diode functions (ie, unidirectional conduction and reverse cut-off functions), which are not limited in the embodiments of the present application.

In this embodiment of the present application, when the transmitter of the first communication node or the transmitter of the second communication node is at a low level, the on-board communication circuit may implement the receiver of the first communication node and the receiver of the second communication node. The receiving ends of the communication nodes are all low-level, so that the CAN communication on the board is realized without the CAN transceiver, which not only makes full use of the advantages of CAN communication in the board, but also reduces the hardware cost.

Please refer to FIG. 2b. FIG. 2b is a schematic structural diagram of another on-board communication circuit disclosed in an embodiment of the present application. As shown in FIG. 2b, the intra-board communication circuit 30 described in this embodiment is used to realize intra-board communication between the first communication node 10 and the second communication node 20, and the intra-board communication circuit includes a first diode D1 , the second diode D2, the third diode D3, the fourth diode D4, the first resistor R1, the second resistor R2 and the isolation chip 301, wherein:

The anode of the third diode D3 is connected to the receiving end RX1 of the first communication node 10 , and the anode of the fourth diode D4 is connected to the receiving end RX2 of the second communication node 20 ;

The negative pole of the third diode D3 is connected to the first output terminal OUT1 of the isolation chip 301, the receiving terminal RX1 of the first communication node 10 is connected to the second input terminal IN2 of the isolation chip 301, and the The cathode of the fourth diode D4 is connected to the second output terminal OUT2 of the isolation chip 301 , and the receiving terminal RX2 of the second communication node 20 is connected to the first input terminal IN1 of the isolation chip 301 . The transmitting end TX1 of the first communication node 10 and/or the transmitting end TX2 of the second communication node 20 are at low level, and the on-board communication circuit 30 realizes the receiving end RX1 of the first communication node 10 and all The receiving end RX2 of the second communication node 20 is low level; if the transmitting end TX1 of the first communication node 10 and the transmitting end TX2 of the second communication node 20 are both high level, the intra-board communication The circuit 30 realizes that the receiving end RX1 of the first communication node 10 and the receiving end RX2 of the second communication node 20 are at a high level.

When the transmitting terminal TX1 of the first communication node 10 is at a low level and the transmitting terminal TX2 of the second communication node 20 is at a low level, the first diode D1 and the second diode in the in-board communication circuit 30 Both the tubes D2 are turned on, at this time, the receiving end RX1 of the first communication node 10 and the receiving end RX2 of the second communication node 20 are both low level;

When the transmitting terminal TX1 of the first communication node 10 is at a low level and the transmitting terminal TX2 of the second communication node 20 is at a high level, the first diode D1 in the on-board communication circuit 30 is turned on, and the second The diode D2 is non-conducting, the third diode D3 is non-conducting, and the fourth diode D4 is conducting. At this time, the receiving end RX1 of the first communication node 10 and the receiving end RX2 of the second communication node 20 are both low level;

When the transmitting terminal TX1 of the first communication node 10 is at a high level and the transmitting terminal TX2 of the second communication node 20 is at a low level, the first diode D1 in the on-board communication circuit 30 is not conducting, and the first diode D1 in the on-board communication circuit 30 is not conducting. The second diode D2 is turned on, the third diode D3 is turned on, and the fourth diode D4 is turned off. At this time, the receiving end RX1 of the first communication node 10 and the receiving end RX2 of the second communication node 20 are both low level;

In the case that the transmitting end TX1 of the first communication node 10 and the transmitting end TX2 of the second communication node 20 are both at a high level, the first diode D1 and the second diode D2 in the intra-board communication circuit 30 are both Not conducting, at this time, the receiving end RX1 of the first communication node 10 and the receiving end RX2 of the second communication node 20 are at a high level.

In this embodiment of the present application, when the transmitter of the first communication node or the transmitter of the second communication node is at a low level, the on-board communication circuit may implement the receiver of the first communication node and the receiver of the second communication node. The receiving end of the communication node is all low level, and in the case that the transmitting end of the first communication node and the transmitting end of the second communication node are both high level, the on-board communication circuit can realize the first communication node. The receiving end of the second communication node and the receiving end of the second communication node are both high level, so that the CAN communication in the board is realized without the CAN transceiver, which not only makes full use of the advantages of CAN communication in the board, but also reduces the hardware cost.

Among them, the CAN bus can be used to transmit data, and can also be used to transmit control commands. When transmitting data, the data block may be encoded in a data block unit to obtain a data block with a minimum unit of bits (information contained in one bit of a binary number=1 bit).

CAN is one of the most widely used fieldbuses in the world. In the early 1980s, the German Bosch company developed the CAN bus in order to solve the problem of data exchange between numerous control and test instruments in modern automobiles. CAN bus can effectively support serial communication network of distributed control or real-time control, and has the advantages of strong anti-interference and reliable use. Such as distributed environmental monitoring system, greenhouse environmental monitoring system, substation monitoring system, etc.

CAN bus is a serial data communication protocol, and its communication interface (for example, the first communication node 10 and the second communication node 20) integrates the physical layer and data link layer functions of the CAN protocol, which can complete the conversion of data. Frame processing, including bit stuffing, data block coding, cyclic redundancy check, priority determination, etc. Users can develop application layer communication protocols that meet the actual needs of the system on its basis. One of the biggest features of the CAN protocol is that the traditional station address coding is abolished, and the communication data block coding is replaced. This method can make the number of nodes in the network theoretically unlimited, and also allow different nodes to simultaneously received the same data.

CAN bus has the following advantages:

(1) The CAN bus is a multi-master bus, that is, each node machine can become the master, and the node machines can also communicate;

(2) The communication medium of CAN bus can be twisted pair, coaxial cable or optical fiber, and the communication rate can reach 1Mbps;

(3) The length of the data segment transmitted in the CAN bus is up to 8 bytes, which can meet the general requirements of control commands, working states and test data in the usual industrial fields. At the same time, 8 bytes will not occupy the bus for too long, thus ensuring the real-time communication;

(4) The CAN protocol adopts cyclic redundancy check (CRC) check and can provide corresponding error handling functions to ensure the reliability of data communication;

(5) CAN can work in a multi-master mode, and any node on the network can actively send information to other nodes on the bus at any time, realizing point-to-point, point-to-multipoint and global broadcasting. Send and receive data in several ways;

(6) CAN adopts non-destructive bus arbitration technology. When two nodes send information to the bus at the same time, the node with low priority actively stops data transmission, while the node with high priority can continue to transmit data without being affected, saving Bus collision arbitration time.

Typical application scenarios of CAN bus: The master node receives field data sent by other nodes, such as field temperature, current, pressure and other parameters, the master node generates various control commands after processing, and sends the control commands to various other nodes through the CAN bus. node.

In the embodiment of the present application, the first resistor R1 and the second resistor R2 are pull-up resistors, and the resistance values of the first resistor R1 and the second resistor R2 may be the same or different. The first resistor R1 and the second resistor R2 can improve the noise tolerance of the signal at the receiving end of the communication node and enhance the anti-interference ability. The first diode D1 and the second diode D2 may be common switching diodes, low power consumption switching diodes, etc. The parameters of the first diode D1 and the second diode D2 may be the same or different.

The isolation chip 301 may be an optocoupler isolation chip, so that there is no direct electrical connection between the two isolated communication nodes, mainly to prevent interference caused by the electrical connection. For example, the first communication node 10 is a high-voltage node, and the second communication node 20 is a low-voltage node, and the ground levels of the two are different. For another example, the first communication node 10 works in the DC mode, and the second communication node 20 works in the AC mode, and the ground levels of the two are also different. If the isolation chip 301 is not used between the two communication nodes, the two communication nodes will interfere with each other. After adopting this scheme, such problems will be avoided.

In the embodiment of the present application, the on-board communication circuit can be used in a board that does not need a large cable to carry a large current, such as a printed circuit board (PCB), etc. The communication node can be a micro-control unit MCU, or It is a unit that interconnects the micro-control unit MCU and other electronic components, and can also be an integrated electronic device including the micro-control unit MCU.

Please refer to Table 1, which is the level change between the communication nodes of the on-board communication circuit of Figures 2a and 2b. In Table 1, the high level is "1" and the low level is "0". It can be seen from Table 1 that as long as either the transmitting end (TX1 or TX2) of the first communication node and the second communication node is at a low level, the receiving end (both RX1 and RX2) of the first communication node and the second communication node is at a low level. It is low level, when the transmitting end (TX1 and TX2) of the first communication node and the second communication node are both high level, the receiving end (RX1 and RX2) of the first communication node and the second communication node are both high level The on-board communication circuit of Fig. 2a and Fig. 2b does not use the CAN transceiver of Fig. 1a and does not use the CAN signal, and can also realize the function of CAN communication.

The high level and the low level correspond to the "1" and "0" of the digital signal, respectively. There is no intersection between the voltage range of the analog signal corresponding to the high level and the voltage range of the analog signal corresponding to the low level. For example, the voltage range of the analog signal corresponding to the high level is greater than 2.5V, and the voltage range of the analog signal corresponding to the low level is 0-1.2V.

Table 1

When the transmitting terminal TX1 of the first communication node 10 is at a low level and the transmitting terminal TX2 of the second communication node 20 is at a low level, the first diode D1 and the second diode in the in-board communication circuit 30 Both the tubes D2 are turned on, so that the receiving end RX1 of the first communication node 10 and the receiving end RX2 of the second communication node 20 are both at low level. As shown in Fig. 2b, it is assumed that the level of the first power supply terminal and the second power supply terminal is preset to 3.3V, the voltage range of the analog signal corresponding to the high level is 2.5-10V, and the voltage range of the analog signal corresponding to the low level is 0～1.2V. The transmission terminal TX1 of the first communication node 10 is at a low level (eg, 0V), and the transmission terminal TX2 of the second communication node 20 is at a low level (eg, 0V). Since the negative electrode of the first diode D1 is at 0V, The anode of the first diode D1 is connected to the voltage 3.3V of the first power supply terminal through the first resistor R1, and the first diode D1 is turned on. Similarly, since the cathode of the second diode D2 is 0V, and the anode of the second diode D2 is connected to the voltage of 3.3V at the second power supply terminal through the second resistor R2, the second diode D1 is turned on. After the first diode D1 and the second diode D2 are both turned on, the level of the receiving terminal of the communication node is the same as the level of the transmitting terminal, and the isolation chip 301 is turned on (ie, the first input terminal IN1 of the isolation chip 301 is turned on). connected with the first output terminal OUT1, and the second input terminal IN2 is connected with the second output terminal OUT2), so that the receiving terminal RX1 of the first communication node 10 and the receiving terminal RX2 of the second communication node 20 are both low power flat.

When the transmitting terminal TX1 of the first communication node 10 is at a low level and the transmitting terminal TX2 of the second communication node 20 is at a high level, the first diode D1 in the on-board communication circuit 30 is turned on, and the second The diode D2 is non-conducting, the third diode D3 is non-conducting, and the fourth diode D4 is conducting, so that the receiving end RX1 of the first communication node 10 and the receiving end RX2 of the second communication node 20 are both low level. As shown in Fig. 2b, it is assumed that the level of the first power supply terminal and the second power supply terminal is preset to 3.3V, the voltage range of the analog signal corresponding to the high level is 2.5-10V, and the voltage range of the analog signal corresponding to the low level is 0～1.2V. The transmission terminal TX1 of the first communication node 10 is at a low level (for example, 0V), that is, the voltage of the negative electrode 32 of the first diode D1 is “0”, and the transmission terminal TX2 of the second communication node 20 is at a high level ( For example, 5V), that is, the voltage of the cathode 42 of the second diode D2 is "5V". Since the cathode of the first diode D1 is 0V, and the anode of the first diode D1 is connected to the voltage of 3.3V at the first power supply terminal through the first resistor R1, the first diode D1 is turned on. The voltage drop is generally 0.2-0.7V, and the anode voltage of the first diode D1 is 0.2-0.7V. Since the cathode of the second diode D2 is 5V, and the anode of the second diode D2 is connected to the voltage of 3.3V at the second power supply terminal through the second resistor R2, the second diode D2 is not conducting, and the second diode D2 is not conducting. The positive voltage of D2 is 3.3V. Since the positive electrode of the third diode D3 and the positive electrode of the first diode D1 have the same voltage of 0.2-0.7V, the negative electrode of the third diode D3 passes through the isolation chip 301 and the positive electrode of the second diode D2 ( 3.3V) connection, then the third diode D3 is not conducting. The positive electrode of the fourth diode D4 and the positive electrode of the second diode D2 have the same voltage as 3.3V, and the negative electrode of the fourth diode D4 passes through the isolation chip 301 and the positive electrode of the first diode D1 (0.2～ 0.7V) connection, then the fourth diode D4 is turned on. When the first diode D1 is turned on, the level of the receiving end RX1 of the first communication node 10 is the same as the level of the sending end TX1, which is a low level; when the second diode D2 is not turned on, due to the fourth diode The tube D4 is turned on, the first diode D1 is turned on, the receiving end RX1 of the first communication node 10 will pass the low level through the second input end IN2 of the isolation chip 301, the second output end OUT2 of the isolation chip 301, the fourth The diode D4 is transmitted to the receiving end RX2 of the second communication node 20, and the receiving end RX2 of the second communication node 20 is also low level.

When the transmitting terminal TX1 of the first communication node 10 is at a high level and the transmitting terminal TX2 of the second communication node 20 is at a low level, the first diode D1 in the on-board communication circuit 30 is not conducting, and the first diode D1 in the on-board communication circuit 30 is not conducting. The second diode D2 is turned on, the third diode D3 is turned on, and the fourth diode D4 is turned off, so that the receiving end RX1 of the first communication node 10 and the receiving end RX2 of the second communication node 20 are both low level. As shown in Fig. 2b, it is assumed that the level of the first power supply terminal and the second power supply terminal is preset to 3.3V, the voltage range of the analog signal corresponding to the high level is 2.5-10V, and the voltage range of the analog signal corresponding to the low level is 0～1.2V. The transmission terminal TX1 of the first communication node 10 is at a high level (for example, 5V), that is, the voltage of the negative electrode 32 of the first diode D1 is “5V”, and the transmission terminal TX2 of the second communication node 20 is at a low level ( For example, 0V), that is, the voltage of the cathode 42 of the second diode D2 is "0V". Since the cathode of the first diode D1 is 5V, and the anode of the first diode D1 is connected to the voltage of 3.3V at the first power supply terminal through the first resistor R1, the first diode D1 is not conducting, and the first diode D1 is not conductive. The positive voltage of D1 is 3.3V. Since the cathode of the second diode D2 is 0V, and the anode of the second diode D2 is connected to the voltage of the second power supply terminal 3.3V through the second resistor R2, the second diode D2 is turned on. The voltage drop is generally 0.2-0.7V, and the anode voltage of the second diode D2 is 0.2-0.7V. Since the positive electrode of the third diode D3 and the positive electrode of the first diode D1 have the same voltage as 3.3V, the negative electrode of the third diode D3 is separated from the positive electrode of the second diode D2 through the isolation chip 301 (0.2~ 0.7V) connection, then the third diode D3 is turned on. The anode voltage of the fourth diode D4 is the same as the anode voltage of the second diode D2, and both are 0.2-0.7V, and the cathode of the fourth diode D4 passes through the isolation chip 301 and the anode of the first diode D1 ( 3.3V) connection, the fourth diode D4 is not conducting. When the second diode D2 is turned on, the transmitting end TX2 and the receiving end RX2 of the second communication node 20 are both at low level. Since the third diode D3 is turned on, the receiving terminal RX2 of the second communication node 20 will pass the low level through the first input terminal IN1 of the isolation chip 301 , the first output terminal OUT1 of the isolation chip 301 , and the third diode D3 It is transmitted to the receiving end RX1 of the first communication node 10, and the receiving end RX1 of the first communication node 10 is also low level.

In the case that the transmitting end TX1 of the first communication node 10 and the transmitting end TX2 of the second communication node 20 are both at a high level, the first diode D1 and the second diode D2 in the intra-board communication circuit 30 are both It is not turned on, so that the receiving end RX1 of the first communication node 10 and the receiving end RX2 of the second communication node 20 are both at a high level. As shown in Fig. 2b, it is assumed that the level of the first power supply terminal and the second power supply terminal is preset to 3.3V, the voltage range of the analog signal corresponding to the high level is 2.5-10V, and the voltage range of the analog signal corresponding to the low level is 0～1.2V. The transmitting end TX1 of the first communication node 10 and the transmitting end TX2 of the second communication node 20 are both at a high level (for example, 5V), that is, the voltage of the negative electrode 32 of the first diode D1 is “5V”. Similarly, The voltage of the cathode 42 of the second diode D2 is also "V". The anode of the first diode D1 is connected to the voltage 3.3V of the first power supply terminal through the first resistor R1, then the first diode D1 is not conducting, and the anode voltage of the first diode D1 is 3.3V. Similarly, the anode of the second diode D2 is connected to the voltage of 3.3V at the second power supply terminal through the second resistor R2, the second diode D2 is non-conductive, and the anode voltage of the second diode D2 is 3.3V. At this time, the receiving end RX1 of the first communication node 10 and the receiving end RX2 of the second communication node 20 are both 3.3V, that is, a high level.

In the embodiments of the present application, the on-board communication circuit can be used to implement on-board CAN communication between two communication nodes without adding an external CAN transceiver to the in-board communication node, thereby reducing hardware costs. The embodiments of the present application mainly describe the structure and working principle of the in-board communication circuit, and then describe optional means for optimizing the in-board communication circuit.

Optionally, please refer to FIG. 3 , FIG. 3 is obtained by further optimization on the basis of FIG. 2 a , and FIG. 3 is a schematic structural diagram of another on-board communication circuit disclosed in an embodiment of the present application. As shown in FIG. 3 , the on-board communication circuit described in this embodiment further includes: a first filter circuit and a second filter circuit; the first end 11 of the first resistor R1 is connected to the first communication node through the first filter circuit The receiving end RX1 of 10; the first end 21 of the second resistor R2 is connected to the receiving end RX2 of the second communication node 20 through the second filter circuit. in:

The first filter circuit includes a third resistor R3 and a first capacitor C1, and the second filter circuit includes a fourth resistor R4 and a second capacitor C2; the first end 71 of the first capacitor C1 is connected to the first end 51 of the third resistor R3 and The receiving end RX1 of the first communication node 10, the second end 72 of the first capacitor C1 is connected to the first ground end, the second end 52 of the third resistor R3 is connected to the first end 11 of the first resistor R1; The first terminal 81 is connected to the second terminal 62 of the fourth resistor R4 and the receiving terminal RX2 of the second communication node 20 , the second terminal 82 of the second capacitor C2 is connected to the second ground terminal, and the first terminal 61 of the fourth resistor R4 is connected to The first end 21 of the second resistor R2.

When communicating between communication nodes, the receiving end of the communication node may be interfered by various factors and it is difficult to receive pure signals. The first filter circuit and the second filter circuit have strong anti-interference, so that the on-board communication circuit can not only Realizing intra-board CAN communication between communication nodes can also reduce interference signals that may be received by the receiving end of the communication nodes, and realize more accurate intra-board CAN communication.

Optionally, the above-mentioned first filter circuit and second filter circuit may also be added on the basis of FIG. 2 b , and the specific principle is similar to that of FIG. 3 , which will not be repeated here.

Please refer to FIG. 4 , which is a schematic structural diagram of an in-board communication device disclosed in an embodiment of the present application. As shown in FIG. 4 , the intra-board communication device described in this embodiment includes a first communication node 10 , a second communication node 20 , and the intra-board communication shown in any one of FIGS. 2 a , 2 b or 3 . circuit 30. in:

The ground terminal 103 of the first communication node 10 is connected to the third ground terminal, the ground terminal 203 of the second communication node 20 is connected to the fourth ground terminal, and the third ground terminal is different from the fourth ground terminal;

The power supply terminal 104 of the first communication node 10 is connected to the first auxiliary power supply, and the power supply terminal 204 of the second communication node 20 is connected to the second auxiliary power supply;

Both the first communication node 10 and the second communication node 20 include a microcontroller unit MCU and a CAN controller.

In this embodiment of the present application, the micro-control unit MCU in the first communication node 10 and the micro-control unit MCU in the second communication node 20 may be the same micro-control unit, or may be different micro-control units.

In the embodiment of the present application, the micro-control unit MCU and the CAN controller are connected to each other and work together to form a communication node. The two communication nodes in the on-board communication device realize intra-board CAN communication with no common ground (that is, the third ground terminal and the fourth ground terminal are not the same ground terminal) through the on-board communication circuit.

Please refer to FIG. 5 , which is a schematic structural diagram of another in-board communication device disclosed in an embodiment of the present application. As shown in FIG. 5 , the intra-board communication device described in this embodiment includes a first communication node 10 , a second communication node 20 and the intra-board communication shown in any one of FIG. 2 a , FIG. 2 b or FIG. 3 . circuit 30. in:

Both the first communication node 10 and the second communication node 20 include a micro-control unit MCU, and a CAN controller is integrated in the micro-control unit MCU.

In the embodiment of the present application, a CAN controller is integrated in the micro-control unit MCU, and the micro-control unit MCU can directly constitute a communication node. The two communication nodes in the on-board communication device realize intra-board CAN communication with no common ground (that is, the third ground terminal and the fourth ground terminal are not the same ground terminal) through the on-board communication circuit.

The in-board communication circuit and the in-board communication device provided by the embodiments of the present application have been described in detail above. The principles and implementations of the present application are described with specific examples in this paper. The descriptions of the above embodiments are only used for Help to understand the method of the present application and its core idea; meanwhile, for those of ordinary skill in the art, according to the idea of the present application, there will be changes in the specific implementation and application scope. In summary, the content of this specification It should not be construed as a limitation of this application.

Claims

An intra-board communication circuit used for realizing intra-board communication between a first communication node and a second communication node, characterized in that the intra-board communication circuit comprises a first diode, a second Two diodes, a first resistor, a second resistor and an isolation chip;

The transmitting end of the first communication node is connected to the cathode of the first diode, and the anode of the first diode is connected to the receiving end of the first communication node and the first end of the first resistor, The second end of the first resistor is connected to the first power supply end; the transmitting end of the second communication node is connected to the cathode of the second diode, and the anode of the second diode is connected to the second communication node the receiving end of the node and the first end of the second resistor, the second end of the second resistor is connected to the second power supply end;

The transmitting end of the first communication node is connected to the second input end of the isolation chip, the receiving end of the first communication node is connected to the first output end of the isolation chip, and the transmitting end of the second communication node When the first input end of the isolation chip is connected, and the receiving end of the second communication node is connected to the second output end of the isolation chip, if the transmitting end of the first communication node and/or the second The sending end of the communication node is at low level, and the on-board communication circuit realizes that the receiving end of the first communication node and the receiving end of the second communication node are at low level.
The intra-board communication circuit according to claim 1, wherein the intra-board communication circuit further comprises a third diode and a fourth diode, and an anode of the third diode is connected to the first diode the receiving end of the communication node, the anode of the fourth diode is connected to the receiving end of the second communication node;

The cathode of the third diode is connected to the first output terminal of the isolation chip, the receiving terminal of the first communication node is connected to the second input terminal of the isolation chip, and the cathode of the fourth diode is connected to the first output terminal of the isolation chip. When the second output end of the isolation chip is connected, and the receiving end of the second communication node is connected to the first input end of the isolation chip, if the transmitting end of the first communication node and/or the second communication node The sending end of the communication node is at low level, and the on-board communication circuit realizes that the receiving end of the first communication node and the receiving end of the second communication node are at low level; if the sending end of the first communication node Both the terminal and the transmitting terminal of the second communication node are at a high level, and the on-board communication circuit realizes that the receiving terminal of the first communication node and the receiving terminal of the second communication node are at a high level.
The on-board communication circuit according to claim 1 or 2, wherein the on-board communication circuit further comprises a first filter circuit; the first end of the first resistor is connected to the The receiving end of the first communication node.
The on-board communication circuit according to claim 3, wherein the first filter circuit comprises a third resistor and a first capacitor; the first end of the first capacitor is connected to the first end of the third resistor . The receiving end of the first communication node, the second end of the first capacitor is connected to the first ground end, and the second end of the third resistor is connected to the first end of the first resistor.
The intra-board communication circuit according to claim 4, wherein the intra-board communication circuit further comprises a second filter circuit; the first end of the second resistor is connected to the second filter circuit through the second filter circuit The receiver of the communication node.
The intra-board communication circuit according to claim 5, wherein the second filter circuit comprises a fourth resistor and a second capacitor; the first end of the second capacitor is connected to the second end of the fourth resistor . The receiving end of the second communication node, the second end of the second capacitor is connected to the second ground end, and the first end of the fourth resistor is connected to the first end of the second resistor.
An intra-board communication device, characterized in that the intra-board communication device comprises a first communication node, a second communication node and the intra-board communication circuit according to any one of claims 1 to 6.
The on-board communication device according to claim 7, wherein the ground terminal of the first communication node is connected to a third ground terminal, the ground terminal of the second communication node is connected to a fourth ground terminal, and the third ground terminal is connected to the ground terminal. The ground end is different from the fourth ground end.
The on-board communication device according to claim 7, wherein the first communication node and the second communication node both comprise a microcontroller unit and a CAN controller.
The on-board communication device according to claim 7, wherein the first communication node and the second communication node both comprise a micro-control unit, and a CAN controller is integrated in the micro-control unit.