CN113169920B

CN113169920B - On-board communication circuit and device based on CAN communication

Info

Publication number: CN113169920B
Application number: CN202080006650.0A
Authority: CN
Inventors: 刘鹏飞; 苏碧锋; 胡定高; 吴壬华
Original assignee: Shenzhen Shinry Technologies Co Ltd
Current assignee: Shenzhen Shinry Technologies Co Ltd
Priority date: 2020-08-26
Filing date: 2020-08-26
Publication date: 2022-07-19
Anticipated expiration: 2040-08-26
Also published as: CN113169920A; WO2022041000A1

Abstract

The embodiment of the application discloses an on-board communication circuit and a device based on CAN communication, wherein the on-board communication circuit is used for realizing the on-board CAN communication among a first communication node, a second communication node and a third communication node; the receiving end of the first communication node is connected with the receiving end of the second communication node; a first input end of the on-board communication circuit is connected with a sending end of the first communication node, a second input end of the on-board communication circuit is connected with a sending end of the second communication node, and a third input end of the on-board communication circuit is connected with a sending end of the third communication node; a first output end of the on-board communication circuit is connected with a receiving end of the first communication node, and a second output end of the on-board communication circuit is connected with a receiving end of the third communication node; by implementing the embodiment of the application, CAN signals between the communication nodes CAN be isolated, CAN signal interference between the communication nodes is eliminated, and the cost is saved.

Description

On-board communication circuit and device based on CAN communication

Technical Field

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

Background

At present, buses such as a Serial Communication Interface (SCI), a Serial Peripheral Interface (SPI), and an I2C (inter-integrated circuit) are generally used for communication between communication nodes.

A Controller Area Network (CAN) bus is a multi-master bus, i.e., each node CAN be a master and CAN communicate with each other. The CAN communication is widely applied to the fields of automobiles, medical treatment, ships, aviation and the like due to the advantages of excellent performance, unique design, high reliability and the like. The CAN bus has its unique advantages over SCI, SPI, I2C, etc. buses. In CAN communication, each communication node may include a Micro Controller Unit (MCU), a CAN controller, and a CAN transceiver, that is, each communication node may be a host, and the communication nodes may also transmit and receive signals of other communication nodes through a bus for free communication.

Because CAN has the advantages of strong real-time performance, long transmission distance, strong anti-electromagnetic interference capability, low cost and the like, more and more products for realizing multi-node information interaction by using CAN communication are used, and in order to avoid mutual interference in the multi-channel signal interaction process, an isolation chip is required to be added between each node to isolate CAN signals.

Disclosure of Invention

The embodiment of the application provides an on-board communication circuit and device based on CAN communication, CAN realize that three communication nodes in the board or in the piece under no transceiver adopt the CAN communication of different levels, and with the CAN signal isolation between the communication node, eliminate the CAN signal interference between the communication node, reduced hardware cost.

In a first aspect of the embodiments of the present application, an on-board communication circuit based on Controller Area Network (CAN) communication is provided, where the on-board communication circuit is used to implement on-board CAN communication among a first communication node, a second communication node, and a third communication node;

a ground terminal of the first communication node and a ground terminal of the second communication node are connected to the same ground line, the ground terminal of the first communication node and the ground terminal of the third communication node are at different levels, and the ground terminal of the second communication node and the ground terminal of the third communication node are at different levels; the receiving end of the first communication node is connected with the receiving end of the second communication node;

a first input end of the on-board communication circuit is connected with a sending end of the first communication node, a second input end of the on-board communication circuit is connected with a sending end of the second communication node, and a third input end of the on-board communication circuit is connected with a sending end of the third communication node; a first output end of the on-board communication circuit is connected with a receiving end of the first communication node, and a second output end of the on-board communication circuit is connected with a receiving end of the third communication node;

the on-board communication circuit is configured to implement that a receiving end of the first communication node, a receiving end of the second communication node, and a receiving end of the third communication node are at a low level when a transmitting end of the first communication node, a transmitting end of the second communication node, or a transmitting end of the third communication node is at a low level;

the on-board communication circuit is further configured to implement that a receiving end of the first communication node, a receiving end of the second communication node, and a receiving end of the third communication node are at a high level when the transmitting end of the first communication node, the transmitting end of the second communication node, and the transmitting end of the third communication node are at a high level;

the on-board communication circuit is further used for isolating the CAN signal sent by the first communication node from the CAN signal sent by the third communication node, and the on-board communication circuit is further used for isolating the CAN signal sent by the second communication node from the CAN signal sent by the third communication node.

The on-board communication circuit comprises a first logic AND gate, a second logic AND gate, a third logic AND gate and an isolation circuit;

the transmitting end of the first communication node is connected with the first input end of the second logic AND gate, the receiving end of the first communication node is connected with the output end of the first logic AND gate, the transmitting end of the second communication node is connected with the second input end of the second logic AND gate, the first input end of the first logic AND gate is connected with the second input end of the isolation circuit and the output end of the second logic AND gate, the second input end of the first logic AND gate is connected with the first output end of the isolation circuit, the first input end of the isolation circuit is connected with the first input end of the third logic AND gate and the transmitting end of the third communication node, and the second output end of the isolation circuit is connected with the second input end of the third logic AND gate.

Under the condition that the transmitting end of the first communication node or the transmitting end of the second communication node is at a low level, the output end of the second logic and gate is at the low level, and the output end of the first logic and gate is at the low level, so that the receiving end of the first communication node and the receiving end of the second communication node are at the low level; the isolation circuit transmits the low level of the second input end of the isolation circuit to the second output end of the isolation circuit, and the output end of the third logic and gate is at the low level, so that the receiving end of the third communication node is at the low level;

under the condition that the sending end of the third communication node is at a low level, the output end of the third logical AND gate is at a low level, so that the receiving end of the third communication node is at a low level; the isolation circuit transmits the low level of the first input end of the isolation circuit to the first output end of the isolation circuit, and the output end of the first logic AND gate is at the low level, so that the receiving end of the first communication node and the receiving end of the second communication node are at the low level.

Under the condition that the transmitting end of the first communication node, the transmitting end of the second communication node and the transmitting end of the third communication node are at high levels, the output end of the second logic and gate is at high levels, the isolation circuit transmits the high level of the first input end of the isolation circuit to the first output end of the isolation circuit, the isolation circuit transmits the high level of the second input end of the isolation circuit to the second output end of the isolation circuit, the output end of the first logic and gate is at high levels, and the output end of the third logic and gate is at high levels, so that the receiving end of the first communication node, the receiving end of the second communication node and the receiving end of the third communication node are at high levels.

Wherein the on-board communication circuit further comprises a first filter circuit, a second filter circuit and a third filter circuit; the first filter circuit is arranged between the receiving end of the first communication node and the output end of the first logic AND gate, the second filter circuit is arranged between the receiving end of the second communication node and the output end of the first logic AND gate, and the third filter circuit is arranged between the receiving end of the third communication node and the output end of the third logic AND gate.

The first filter circuit comprises a first resistor and a first capacitor, the second filter circuit comprises a second resistor and a second capacitor, and the third filter circuit comprises a third resistor and a third capacitor;

a first end of the first resistor is connected with a first end of the first capacitor and a receiving end of the first communication node, a second end of the first capacitor is grounded, and a second end of the first resistor is connected with an output end of the first logic and gate;

a first end of the second resistor is connected with a first end of the second capacitor and a receiving end of the second communication node, a second end of the second capacitor is grounded, and a second end of the second resistor is connected with an output end of the first logic and gate;

the first end of the third resistor is connected with the first end of the third capacitor and the receiving end of the third communication node, the second end of the third capacitor is grounded, and the second end of the third resistor is connected with the output end of the third logic and gate.

Wherein the isolation circuit includes an optically coupled isolation chip.

In a second aspect of the embodiments of the present application, an on-board communication device is provided, where the on-board communication device includes a first communication node, a second communication node, a third communication node, and any one of the on-board communication circuits based on controller area network CAN communication in the first aspect of the embodiments of the present application.

The first communication node, the second communication node and the third communication node all comprise a Micro Control Unit (MCU) and a Controller Area Network (CAN) controller.

The first communication node, the second communication node and the third communication node all comprise MCUs, and CAN controllers are integrated in the MCUs.

By implementing the embodiment of the application, aiming at the in-board communication of three communication nodes with different low levels, the in-board communication circuit is arranged among the three communication nodes, the CAN communication of the three communication nodes CAN be realized under the condition that the three communication nodes are not provided with transceivers, the CAN signals among the communication nodes are isolated, the CAN signal interference among the communication nodes is eliminated, and the hardware cost is reduced.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

FIG. 1a is a diagram of a prior art communication node using a CAN transceiver for CAN communication;

FIG. 1b is a schematic diagram of a CAN signal of an on-board communication circuit for CAN communication based on a controller area network CAN communication disclosed in an embodiment of the present application;

FIG. 1c is a schematic level diagram of a CAN signal of a CAN communication implemented by an onboard communication circuit based on CAN communication of a controller area network disclosed in an embodiment of the present application;

FIG. 2 is a schematic structural diagram of an on-board communication circuit based on CAN communication in a controller area network according to an embodiment of the present application;

FIG. 3 is a schematic diagram of an on-board communication circuit based on CAN communication in a controller area network according to an embodiment of the present disclosure;

FIG. 4 is a schematic diagram of an on-board communication circuit based on CAN communication in controller area network according to an embodiment of the present disclosure;

fig. 5 is a schematic structural diagram of an on-board communication device according to an embodiment of the present application;

fig. 6 is a schematic structural diagram of another on-board communication device disclosed in the 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 drawings in the embodiments of the present application. It should be apparent that the described embodiments are some, but not all embodiments of the present application. All other embodiments obtained by a person of ordinary skill in the art without any inventive step based on the embodiments in the present application shall fall within the protection scope of the present application.

The embodiment of the application discloses an on-board communication circuit and an on-board communication device based on CAN communication, and the detailed description is given below.

Reference in the embodiments of the present application to the terms "first", "second", and the like, are used for distinguishing between different objects and not for describing a particular order, and furthermore, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusions.

In the existing CAN communication, each communication node transmits and receives signals of other communication nodes on a bus through a CAN transceiver, so that each communication node must be additionally provided with a CAN transceiver.

Fig. 1a is a schematic diagram of a prior art communication node using a CAN transceiver for CAN communication. As shown in fig. 1a, the first communication node, the second communication node, and the nth communication node may be connected through a CAN bus. The first communication node comprises a first MCU, a first CAN controller and a first CAN transceiver, the second communication node comprises a second MCU, a second CAN controller and a second CAN transceiver, and the like, and the Nth communication node comprises an Nth MCU, an Nth CAN controller and an Nth CAN transceiver. When each communication node transmits a signal, the transmitted signal needs to be converted into a common-mode signal (the common-mode signal includes a common-mode high level CAN _ H and a common-mode low level CAN _ L) by the CAN transceiver for transmission on the CAN bus. The CAN controller CAN be integrated in the MCU or exist independently. Fig. 1a illustrates an example in which a CAN controller is integrated inside a MCU.

Referring to fig. 1b, fig. 1b is a schematic diagram of a CAN signal for implementing CAN communication by using a CAN transceiver disclosed in the embodiment of the present application. Fig. 1b is a CAN signal diagram in CAN communication based on fig. 1a using a CAN transceiver. The CAN signal is a bit stream signal that appears alternately at a dominant level and a recessive level, and may include transmission control commands or may include data segments or blocks. In the CAN signal, "0" represents dominant, dominant corresponds to low level, and "1" represents recessive, recessive corresponds to high level. As shown in fig. 1b, the CAN signal takes a control command as an example, the CAN signal is a dominant level "0" in a first time period, is a recessive level "1" in a second time period, is a dominant level "0" in a third time period, is a dominant level "0" in a fourth time period, and is a recessive level "1" in a fifth time period, a sum of time lengths of the five time periods may be regarded as a period, and levels corresponding to the five time periods may repeatedly appear in a next period, which may be used for periodically transmitting the same control command.

Referring to fig. 1c, fig. 1c is a schematic level diagram of a CAN signal for implementing CAN communication by using a CAN transceiver according to an embodiment of the present disclosure. Fig. 1c is a schematic level diagram of a CAN signal in CAN communication based on fig. 1a using a CAN transceiver. As shown in fig. 1c, the dominant level and the recessive level in the CAN signal correspond to two voltage ranges, instead of two specific values, for example, when the dominant level in the CAN signal is "0V to 1.5V", the corresponding recessive level is "1.5V to 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.

However, when the existing CAN communication method is adopted to realize CAN communication in a board, adding a CAN transceiver to each communication node increases the cost of the in-board communication.

Referring to fig. 2, fig. 2 is a schematic structural diagram of an on-board communication circuit based on CAN communication according to an embodiment of the present disclosure. As shown in fig. 2, the on-board communication circuit 40 described in the present embodiment is used to implement on-board CAN communication between the first communication node 10, the second communication node 20, and the third communication node 30;

the ground terminal VSS1 of the first communication node 10 and the ground terminal VSS2 of the second communication node 20 are connected to the same ground line, the ground terminal VSS1 of the first communication node 10 and the ground terminal VSS3 of the third communication node 30 are different in level, and the ground terminal VSS2 of the second communication node 20 and the ground terminal VSS3 of the third communication node 30 are different in level; the receiving terminal RX1 of the first communication node 10 is connected with the receiving terminal RX2 of the second communication node 20;

a first input 401 of the on-board communication circuit 40 is connected to the transmitting terminal TX1 of the first communication node 10, a second input 402 of the on-board communication circuit 40 is connected to the transmitting terminal TX2 of the second communication node 20, and a third input 403 of the on-board communication circuit 40 is connected to the transmitting terminal TX3 of the third communication node 30; the first output 404 of the on-board communication circuit 40 is connected to the receiving terminal RX1 of the first communication node 10, and the second output 405 of the on-board communication circuit 40 is connected to the receiving terminal RX3 of the third communication node 30;

the onboard communication circuit 40 is configured to, when at least one of the transmitting end TX1 of the first communication node 10, the transmitting end TX2 of the second communication node 20, and the transmitting end TX3 of the third communication node 30 is at a low level, enable the receiving end RX1 of the first communication node 10, the receiving end RX2 of the second communication node 20, and the receiving end RX3 of the third communication node 30 to be at a low level;

the onboard communication circuit 40 is further configured to, when the transmitting end TX1 of the first communication node 10, the transmitting end TX2 of the second communication node 20, and the transmitting end TX3 of the third communication node 30 are all at high level, enable the receiving end RX1 of the first communication node 10, the receiving end RX2 of the second communication node 20, and the receiving end RX3 of the third communication node 30 to be at high level;

the on-board communication circuit 40 is further configured to isolate the CAN signal sent by the first communication node 10 from the CAN signal sent by the third communication node 30, and the on-board communication circuit 40 is further configured to isolate the CAN signal sent by the second communication node 20 from the CAN signal sent by the third communication node 30.

In the embodiment of the present application, the on-board communication circuit 40, which may also be referred to as an on-chip communication circuit, is a communication circuit in the same circuit board or a communication circuit in an integrated circuit of the same chip. The on-board communication circuit 40 may be used in a circuit board that does not require large cables to carry large currents, such as a Printed Circuit Board (PCB) or the like. The communication node may be a Micro Control Unit (MCU), a unit in which the MCU is interconnected with other electronic components, or an integrated electronic device including the MCU. The first communication node 10, the second communication node 20, and the third communication node 30 are all communication nodes that do not include CAN transceivers.

The first communication node 10, the second communication node 20, and the third communication node 30 may implement controller area network CAN bus communication through the on-board communication circuit 40. The first communication node 10, the second communication node 20, and the third communication node 30 may perform data transmission and control command transmission through the on-board communication circuit 40.

The CAN bus CAN be used for transmitting data and CAN also be used for transmitting control commands. When data is transmitted, a data block may be encoded in units of data blocks to obtain a data block having a minimum unit of bits (1 bit of information included in one bit of a binary number).

The CAN bus is one of the most widely used field buses internationally. In the beginning of the 20 th century, in order to solve the problem of data exchange between the numerous control and test instruments in modern cars, the company Bosch, germany, developed a CAN bus. The CAN bus CAN effectively support a serial communication network of distributed control or real-time control, has the advantages of strong anti-interference performance, reliable use and the like, is mainly applied to the automobile industry at first, and is widely applied to the automation fields of the automobile industry, the aviation industry, industrial control and the like, such as a distributed environment monitoring system, a greenhouse environment monitoring system, a transformer substation monitoring system and the like.

The CAN bus is a serial data communication protocol, and the communication interfaces (e.g., the first communication node 10, the second communication node 20, and the third communication node 30) of the CAN bus integrate the functions of the physical layer and the data link layer of the CAN protocol, and CAN complete the framing processing of data, including bit stuffing, data block encoding, cyclic redundancy check, priority discrimination, and the like. On the basis of which the user can develop an application layer communication protocol adapted to the actual needs of the system. The CAN protocol has the main characteristic that the traditional station address coding is abandoned, and the communication data block is coded instead, so that the number of nodes in the network is not limited theoretically by adopting the method, and different nodes CAN receive the same data at the same time.

The CAN bus has the following advantages:

(1) the CAN bus is a multi-master bus, namely each node machine CAN be a host, and the node machines CAN also communicate with each other;

(2) the communication medium of the CAN bus CAN be a twisted pair, a coaxial cable or an optical fiber, and the communication speed CAN reach 1 Mbps;

(3) the length of the data segment transmitted in the CAN bus is at most 8 bytes, and the general requirements of control commands, working states and test data in the common industrial field CAN be met. Meanwhile, 8 bytes can not occupy the bus for too long time, so that the real-time performance of communication is ensured;

(4) the CAN protocol adopts Cyclic Redundancy Check (CRC) check and CAN provide a corresponding error processing function, so that the reliability of data communication is ensured;

(5) the 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, so that data CAN be sent and received in a point-to-point mode, a point-to-multipoint mode and a global broadcasting mode;

(6) the CAN adopts a 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 sending, and the node with high priority CAN continue to transmit data without being influenced, thereby saving the bus conflict arbitration time.

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

The on-board communication circuit 40 of the embodiment of the present application is used for CAN communication between three communication nodes, the first communication node 10 and the second communication node 20 are connected to the same ground, and the third communication node 30 is connected to a different ground from the first communication node 10 and the second communication node 20. If the first communication node 10 and the third communication node 30 are not isolated from each other, the first communication node 10 and the third communication node 30 interfere with each other when performing CAN communication; if the second communication node 20 and the third communication node 30 are not isolated from each other, the second communication node 20 and the third communication node 30 interfere with each other when performing CAN communication. The on-board communication circuit 40 according to the embodiment of the present application CAN isolate the CAN signal sent by the first communication node 10 from the CAN signal sent by the third communication node 30, and CAN also isolate the CAN signal sent by the second communication node 20 from the CAN signal sent by the third communication node 30, thereby avoiding interference when CAN communication is performed between the first communication node 10 and the third communication node 30, and avoiding interference when CAN communication is performed between the second communication node 20 and the third communication node 30.

In this embodiment, when all of the CAN signals transmitted by the transmitting end TX1 of the first communication node 10, the transmitting end TX2 of the second communication node 20, and the transmitting end TX3 of the third communication node 30 are at a high level, the on-board communication circuit 40 may implement that the receiving end RX1 of the first communication node 10, the receiving end RX2 of the second communication node 20, and the receiving end RX3 of the third communication node 30 are at a high level, and implement the original communication function when none of the communication nodes has a CAN transceiver (that is, when the transmitting end of any one of the communication nodes is at a low level, the receiving ends of all the communication nodes are at a low level, and when the transmitting ends of all the communication nodes are at a high level, the receiving ends of all the communication nodes are at a high level).

Referring to table 1, table 1 is a level variation between communication nodes of the on-board communication circuit of fig. 2. As shown in table 1, the high level is "1" and the low level is "0". As can be seen from table 1, as long as any one of the transmitting terminals (TX1 or TX2 or TX3) of the first communication node, the second communication node, and the third communication node is at a low level, the receiving terminals (RX1, RX2, and RX3) of the first communication node, the second communication node, and the third communication node are all at a low level, and when the transmitting terminals (TX1, TX2, and TX3) of the receiving terminals of the first communication node, the second communication node, and the third communication node are all at a high level, the receiving terminals (RX1, RX2, and RX3) of the first communication node, the second communication node, and the third communication node are all at a high level. The on-board communication circuit of fig. 2 CAN also implement the CAN communication function without the CAN transceiver of fig. 1a and without the CAN signal.

The high level and the low level correspond to "1" and "0" of the digital signal, respectively. 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 do not intersect. 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

Wherein TX1 is the sender of the first communication node 10, TX2 is the sender of the second communication node 20, TX3 is the sender of the third communication node 30, RX1 is the receiver of the first communication node 10, RX2 is the receiver of the second communication node 20, and RX3 is the receiver of the third communication node 30.

In the embodiment of the application, the in-board communication of the three communication nodes with different low levels is realized by arranging the in-board communication circuit between the three communication nodes, the CAN communication of the three communication nodes CAN be realized under the condition that the three communication nodes do not have transceivers, CAN signals between the communication nodes are isolated, and the CAN signal interference between the communication nodes is eliminated.

Referring to fig. 3, fig. 3 is a schematic structural diagram of another on-board communication circuit based on CAN communication in a controller area network according to an embodiment of the present disclosure. The on-board communication circuit 40 includes a first logic and gate 41, a second logic and gate 42, a third logic and gate 43, and an isolation circuit 44.

To facilitate understanding by those skilled in the art, the first logical AND gate in fig. 3 is replaced with the symbol "AND 1", the second logical AND gate is replaced with the symbol "AND 2", AND the third logical AND gate is replaced with the symbol "AND 3".

The transmitting terminal TX1 of the first communication node 10 is connected to the first input terminal 421 of the second logical and gate 42, the receiving terminal RX1 of the first communication node 10 is connected to the output terminal 413 of the first logical and gate 41 and the receiving terminal RX2 of the second communication node 20, the transmitting terminal TX2 of the second communication node 20 is connected to the second input terminal 422 of the second logical and gate 42, the first input terminal 411 of the first logical and gate 41 is connected to the second input terminal 443 of the isolation circuit 44 and the output terminal 423 of the second logical and gate 42, the second input terminal 412 of the first logical and gate 41 is connected to the first output terminal 442 of the isolation circuit 44, the first input terminal 441 of the isolation circuit 44 is connected to the first input terminal 431 of the third logical and gate 43 and the transmitting terminal TX3 of the third communication node 30, the second output terminal 444 of the isolation circuit 44 is connected to the second input terminal 432 of the third logical and gate 43, and the output terminal 433 of the third logical and gate 43 is connected to the receiving terminal RX3 of the third communication node 30.

A first input 421 of the second logic and gate 42 may correspond to the first input 401 of the midplane communication circuit 40 in fig. 2, a second input 422 of the second logic and gate 42 may correspond to the second input 402 of the midplane communication circuit 40 in fig. 2, an output 413 of the first logic and gate 41 may correspond to the first output 404 of the midplane communication circuit 40 in fig. 2, an output 433 of the third logic and gate 43 may correspond to the second output 405 of the midplane communication circuit 40 in fig. 2, and a first input 441 of the isolation circuit 44 may correspond to the third input 403 of the midplane communication circuit 40 in fig. 2.

The logical and gate in the embodiments of the present application may be a basic logical gate circuit that performs an and operation. The logic and gates in the embodiment of the present application may be 2-input and gates, and each logic and gate may include two input terminals and one output terminal.

The isolation circuit 44 may be an isolation chip. The isolated two communication nodes are not electrically connected directly, and interference caused by the electrical connection is mainly prevented. For example, the operating voltages of the first communication node 10 and the second communication node 20 are dc high voltage, the operating voltage of the third communication node 30 is dc low voltage, and the ground levels of the first communication node 10 and the third communication node 30 are different. For another example, the operating voltages of the first communication node 10 and the second communication node 20 are dc high voltages, the third communication node 30 operates in an ac mode, and the ground levels of the first communication node 10 and the third communication node 30 are different. If the isolation circuit 44 is not employed between the first communication node 10 and the third communication node 30, the first communication node 10 and the third communication node 30 may interfere with each other. If the isolation circuit 44 is not used between the second communication node 20 and the third communication node 30, the second communication node 20 and the third communication node 30 may interfere with each other. After this scheme of adoption, then can avoid appearing such problem.

Optionally, the isolation circuit 44 may include an optical coupling isolation chip. The case where the operating voltage of the first communication node 10 and the second communication node 20 is a dc high voltage (for example, the operating voltage of the nodes is above 50V), and the operating voltage of the third communication node 30 is a dc low voltage (for example, the operating voltage of the nodes is below 10V) may be applied, and the case where the first communication node 10 and the second communication node 20 are low voltage operating nodes and the third communication node 30 is a high voltage operating node may also be applied.

The first logic and gate 41, the second logic and gate 42, the third logic and gate 43, and the isolation circuit 44 realize a function of "when the transmitting end of any one communication node is at a low level, the receiving ends of all communication nodes are at a low level, and when the transmitting ends of all communication nodes are at a high level, the receiving ends of all communication nodes are at a high level".

Specifically, when the transmitting end TX1 of the first communication node 10 or the transmitting end TX2 of the second communication node 20 is at a low level, the output end 423 of the second logical and gate 42 is at a low level, and since the output end 423 of the second logical and gate 42 is connected to the first input end 411 of the first logical and gate 41, the output end 413 of the first logical and gate 41 is at a low level, so that the receiving ends RX1 of the first communication node 10 and RX2 of the second communication node 20 are at a low level; the isolation circuit 44 transmits the low level at the second input terminal 443 of the isolation circuit 44 to the second output terminal 444 of the isolation circuit 44, and since the second output terminal 444 of the isolation circuit 44 is connected to the second input terminal 431 of the third and logic gate 43, the output terminal 433 of the third and logic gate 43 is at a low level, so that the receiving terminal RX3 of the third communication node 30 is at a low level;

in a case that the transmitting terminal TX3 of the third communication node 30 is at a low level, since the transmitting terminal TX3 of the third communication node 30 is connected to the first input terminal 431 of the third logical and gate 43, the output terminal 433 of the third logical and gate 43 is at a low level, so that the receiving terminal RX3 of the third communication node 30 is at a low level; the isolation circuit 44 transmits the low level at the first input 441 of the isolation circuit 44 to the first output 442 of the isolation circuit 44, and since the first output 442 of the isolation circuit 44 is connected to the second input 412 of the first logic and gate 41, the output 413 of the first logic and gate 41 is at a low level, so 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 low level.

Specifically, in case that the transmitting terminal TX1 of the first communication node 10, the transmitting terminal TX2 of the second communication node 20 and the transmitting terminal TX3 of the third communication node 30 are high, since the transmitting terminal TX1 of the first communication node 10 is connected to the first input 421 of the second logical and gate 42, the output 423 of the second logic and gate 42 is high, the isolation circuit 44 transmits the high level of the first input 441 of the isolation circuit 44 to the first output 442 of the isolation circuit 44, the isolation circuit 44 transmits the high level of the second input 443 of the isolation circuit 44 to the second output 444 of the isolation circuit 44, since the first output 441 of the isolation circuit 44 is connected to the second input 412 of the first logical and gate 41, the output 413 of the first logical and gate 41 is high, so that the receiving terminals RX1 and RX2 of the first and

second communication nodes

10 and 20 are both high; since the second output 444 of the isolation circuit 44 is connected to the second input 432 of the third logical and gate 43, the output 433 of the third logical and gate 43 is high, so that the receiving terminal RX3 of the third communication node 30 is high.

Optionally, please refer to fig. 4, where fig. 4 is a schematic structural diagram of another on-board communication circuit based on controller area network CAN communication disclosed in the embodiment of the present application. Fig. 4 is further optimized based on fig. 3. As shown in fig. 4, on the basis of fig. 3, the on-board communication circuit 40 described in the present embodiment further includes a first filter circuit 50, a second filter circuit 60, and a third filter circuit 70; the first filter circuit 50 is disposed between the receiving terminal RX1 of the first communication node 10 and the output terminal 413 of the first logical and gate 41, the second filter circuit 60 is disposed between the receiving terminal RX2 of the second communication node 20 and the output terminal 413 of the first logical and gate 41, and the third filter circuit 70 is disposed between the receiving terminal RX3 of the third communication node 30 and the output terminal 433 of the third logical and gate 43.

The first filter circuit 50 includes a first resistor R1 and a first capacitor C1, the second filter circuit 60 includes a second resistor R2 and a second capacitor C2, and the third filter circuit 70 includes a third resistor R3 and a third capacitor C3;

a first end of the first resistor R1 is connected to the first end of the first capacitor C1 and the receiving end RX1 of the first communication node 10, a second end of the first capacitor C1 is grounded, and a second end of the first resistor R1 is connected to the output end 413 of the first logic and gate 41;

a first end of the second resistor R2 is connected to the first end of the second capacitor C2 and the receiving end RX2 of the second communication node 20, a second end of the second capacitor C2 is grounded, and a second end of the second resistor R2 is connected to the output end 413 of the first logic and gate 41;

a first end of the third resistor R3 is connected to the first end of the third capacitor C3 and the receiving end RX3 of the third communication node 30, a second end of the third capacitor C3 is grounded, and a second end of the third resistor R3 is connected to the output end 433 of the third logic and gate 43.

When communication is carried out among the communication nodes, the receiving ends of the communication nodes are possibly interfered by various factors and are difficult to receive pure signals, and the first filter circuit, the second filter circuit and the third filter circuit are high in anti-interference performance, so that the on-board communication circuit not only CAN realize on-board CAN communication among the communication nodes, but also CAN reduce interference signals possibly received by the receiving ends of the communication nodes, and the reliability of the on-board CAN communication is improved.

Referring to fig. 5, fig. 5 is a schematic structural diagram of an on-board communication device according to an embodiment of the present application. As shown in fig. 5, the on-board communication apparatus 100 described in this embodiment includes a first communication node 10, a second communication node 20, a third communication node 30, and the on-board communication circuit 40 shown in fig. 2, 3, or 4.

The power supply terminal VDD1 of the first communication node 10 is connected to the first auxiliary power supply, the power supply terminal VDD2 of the second communication node 20 is connected to the second auxiliary power supply, and the power supply terminal VDD3 of the third communication node 30 is connected to the third auxiliary power supply. Optionally, the first auxiliary power supply and the second auxiliary power supply may be the same auxiliary voltage, and the third auxiliary voltage is different from the supply voltage of the first auxiliary power supply.

The first communication node 10, the second communication node 20, and the third communication node 30 may each include a micro control unit MCU and a CAN controller, which are separate elements. As shown in fig. 5, the first communication node 10 includes an MCU1 and a CAN controller 1, the second communication node 20 includes an MCU2 and a CAN controller 2, and the third communication node 30 includes an MCU3 and a CAN controller 3.

The CAN controller is used for controlling the corresponding communication nodes to transmit and receive data frames according to the CAN bus protocol control.

In the embodiment of the application, the MCU and the CAN controller are connected with each other and cooperatively work to form a communication node together. And three communication nodes in the board communication device realize the board CAN communication through the board communication circuit.

Referring to fig. 6, fig. 6 is a schematic structural diagram of another on-board communication device disclosed in the embodiment of the present application. As shown in fig. 6, the on-board communication apparatus described in the present embodiment includes a first communication node 10, a second communication node 20, a third communication node 30, and an on-board communication circuit 40 shown in fig. 2, 3, or 4. Wherein:

the first communication node 10, the second communication node 20 and the third communication node 30 each include a micro control unit MCU in which a CAN controller is integrated. As shown in fig. 6, the first communication node 10 includes an MCU1, a CAN controller 1 integrated within an MCU1, the second communication node 20 includes an MCU2, a CAN controller 2 integrated within an MCU2, the third communication node 30 includes an MCU3, and a CAN controller 3 integrated within an MCU 3.

In the embodiment of the application, the CAN controller is integrated in the MCU, and the MCU CAN directly form a communication node. And three communication nodes in the on-board communication device realize the on-board CAN communication through the on-board communication circuit.

The on-board communication circuit and the device based on CAN communication provided by the embodiment of the present application are introduced in detail above, and a specific example is applied in the present application to explain the principle and the implementation manner of the present application, and the description of the above embodiment is only used to help understanding the method and the core idea of the present application; meanwhile, for a person skilled in the art, according to the idea of the present application, the specific implementation manner and the application scope may be changed, and in summary, the content of the present specification should not be construed as a limitation to the present application.

Claims

1. An on-board communication circuit based on CAN communication for implementing on-board CAN communication between a first communication node, a second communication node and a third communication node,

a ground terminal of the first communication node and a ground terminal of the second communication node are connected to the same ground wire, the ground terminals of the first communication node and the third communication node are at different levels, and the ground terminal of the second communication node and the ground terminal of the third communication node are at different levels; the receiving end of the first communication node is connected with the receiving end of the second communication node; the working voltage of the first communication node is different from the working voltage of the third communication node;

a first input end of the on-board communication circuit is connected with a sending end of the first communication node, a second input end of the on-board communication circuit is connected with a sending end of the second communication node, and a third input end of the on-board communication circuit is connected with a sending end of the third communication node; a first output end of the on-board communication circuit is connected with a receiving end of the first communication node and a receiving end of the second communication node, and a second output end of the on-board communication circuit is connected with a receiving end of the third communication node;

under the condition that the transmitting end of the first communication node and/or the transmitting end of the second communication node and/or the transmitting end of the third communication node is at a low level, the receiving end of the first communication node, the receiving end of the second communication node and the receiving end of the third communication node are at a low level;

under the condition that the transmitting end of the first communication node, the transmitting end of the second communication node and the transmitting end of the third communication node are all high level, the receiving end of the first communication node, the receiving end of the second communication node and the receiving end of the third communication node are high level;

the on-board communication circuit is further used for isolating a CAN signal sent by the first communication node from a CAN signal sent by the third communication node, and the on-board communication circuit is further used for isolating the CAN signal sent by the second communication node from the CAN signal sent by the third communication node;

the transmitting end of the first communication node is connected with the first input end of the second logic AND gate, the transmitting end of the second communication node is connected with the second input end of the second logic AND gate, the receiving end of the first communication node is connected with the output end of the first logic AND gate, the first input end of the first logic AND gate is connected with the second input end of the isolation circuit and the output end of the second logic AND gate, the second input end of the first logic AND gate is connected with the first output end of the isolation circuit, the first input end of the isolation circuit is connected with the first input end of the third logic AND gate and the transmitting end of the third communication node, the second output end of the isolation circuit is connected with the second input end of the third logic AND gate, and the output end of the third logic AND gate is connected with the receiving end of the third communication node.

2. The on-board communication circuit according to claim 1, wherein when the transmitting end of the first communication node and/or the transmitting end of the second communication node is at a low level, the output end of the second logical and gate is at a low level, and the output end of the first logical and gate is at a low level, so that the receiving end of the first communication node and the receiving end of the second communication node are at a low level; the isolation circuit transmits the low level of the second input end of the isolation circuit to the second output end of the isolation circuit, and the output end of the third logic and gate is at the low level, so that the receiving end of the third communication node is at the low level;

under the condition that the transmitting end of the third communication node is at a low level, the output end of the third logic and gate is at the low level, so that the receiving end of the third communication node is at the low level; the isolation circuit transmits the low level of the first input end of the isolation circuit to the first output end of the isolation circuit, and the output end of the first logic and gate is at the low level, so that the receiving end of the first communication node and the receiving end of the second communication node are at the low level.

3. The on-board communication circuit according to claim 1, wherein when a transmitting end of the first communication node, a transmitting end of the second communication node, and a transmitting end of the third communication node are at a high level, an output end of the second logic and gate is at a high level, the isolation circuit transmits the high level of the first input end of the isolation circuit to the first output end of the isolation circuit, the isolation circuit transmits the high level of the second input end of the isolation circuit to the second output end of the isolation circuit, an output end of the first logic and gate is at a high level, and an output end of the third logic and gate is at a high level, so that a receiving end of the first communication node, a receiving end of the second communication node, and a receiving end of the third communication node are at a high level.

4. The on-board communication circuit of claim 1, further comprising a first filter circuit, a second filter circuit, and a third filter circuit; the first filter circuit is arranged between the receiving end of the first communication node and the output end of the first logic AND gate, the second filter circuit is arranged between the receiving end of the second communication node and the output end of the first logic AND gate, and the third filter circuit is arranged between the receiving end of the third communication node and the output end of the third logic AND gate.

5. The on-board communication circuit of claim 4, wherein the first filtering circuit comprises a first resistor and a first capacitor, the second filtering circuit comprises a second resistor and a second capacitor, and the third filtering circuit comprises a third resistor and a third capacitor;

6. An on-board communication circuit according to any of claims 1 to 5, wherein the isolation circuit comprises an optically coupled isolation chip.

7. An on-board communication device, comprising a first communication node, a second communication node, a third communication node and an on-board communication circuit according to any of claims 1-6.

8. The on-board communication device of claim 7, wherein the first communication node, the second communication node, and the third communication node each comprise a micro control unit and a CAN controller.

9. The on-board communication device of claim 7, wherein the first communication node, the second communication node, and the third communication node each comprise a micro-control unit having a CAN controller integrated therein.