CAN bus communication circuit and communication system

Abstract

The utility model provides a CAN bus communication circuit and a communication system, the communication circuit comprises a twisted-pair bus, a transceiver and a CAN controller, the transceiver is connected with two branches of the twisted-pair bus through two groups of communication wires, a resistor is arranged between the two groups of communication wires, the transceiver comprises a transmitter and a receiver, the transmitter and the receiver are both connected with the CAN controller, and the CAN controller is connected with the transceiver. The transmitter comprises a transmitting element and a suppression element, the transmitting element and the suppression element are both connected with the output end of the CAN controller, the output end of the transmitting element and the output end of the suppression element are connected to the two sets of communication wires respectively, the input end of the receiver is connected to the two sets of communication wires, and the output end of the receiver is connected to the CAN controller. According to the CAN bus communication circuit and the CAN bus communication system provided by the invention, the problem that the whole bus communication is interfered by a bus fault due to the fact that the set terminal resistor is out of action when a far-end bus line breaks down or fractures and the bus impedance is changed can be effectively solved.

Description

Technical Field

[0001] This application relates to the field of communication technology, specifically to CAN bus communication circuits and communication systems. Background Technology

[0002] CAN (Controller Area Network) falls under the category of industrial fieldbuses. Compared to general communication buses, CAN bus data communication offers outstanding reliability, real-time performance, and flexibility. Due to its excellent performance and unique design, it is most widely used in the automotive industry. Some of the world's leading automakers employ CAN bus to achieve data communication between the vehicle's internal control system and various detection and actuator mechanisms. However, CAN networks are constrained by the terminating resistors. If a CAN network loop fails or breaks, the terminating resistors lose their function of ensuring signal integrity, causing the CAN network to malfunction.

[0003] Specifically, the CAN high-speed standard ISO11898 uses a bus structure as its network topology, with a terminating resistor connected at each end of the bus, such as... Figure 1 As shown, the terminating resistors on the CAN bus are connected in parallel on the bus. Placing the terminating resistor at a distant node or placing it alone can effectively absorb reflected waves. However, if there is a fault or break in the bus line at a distant end, the terminating resistor will lose its function, thereby changing the bus impedance. This will cause the entire bus communication to be interfered with by the bus fault, affecting the stable transmission of data. In the matching of terminating resistors, the terminating resistor must be placed at the two farthest ends. If one of them is placed in the middle, the CAN transceiver outside the terminating resistor will be on the branch, which will greatly increase the signal reflection of that node, thus affecting the bus communication. Utility Model Content

[0004] To at least partially solve the above problems, according to a first aspect of this application, an embodiment of this application provides a CAN bus communication circuit, including: a twisted-pair bus, a transceiver, and a CAN controller. The transceiver is connected to two branches of the twisted-pair bus via two sets of communication wires. A resistor is provided between the two sets of communication wires. The transceiver includes a transmitter and a receiver, both of which are connected to the CAN controller. The transmitter includes a transmitting element and a suppressing element, both of which are connected to the output terminal of the CAN controller. The output terminals of the transmitting element and the suppressing element are respectively connected to the two sets of communication wires. The input terminal of the receiver is connected to the two sets of communication wires, and the output terminal of the receiver is connected to the CAN controller.

[0005] In some embodiments, a time-controlled switch chip is provided on the branch line of the suppression element, and the time-controlled switch chip is used to activate or disable the suppression element.

[0006] In some embodiments, the resistor is an adjustable resistor.

[0007] In some embodiments, the resistors are integrated within the transceiver's integrated motherboard.

[0008] According to a second aspect of this application, an embodiment of this application provides a communication system, which includes a CAN bus communication circuit. The CAN bus communication circuit includes a twisted-pair bus, a transceiver, and a CAN controller. The transceiver is connected to two branches of the twisted-pair bus via two sets of communication wires. A resistor is provided between the two sets of communication wires. The transceiver includes a transmitter and a receiver, both of which are connected to the CAN controller. The transmitter includes a transmitting element and a suppressing element, both of which are connected to the output terminal of the CAN controller. The output terminals of the transmitting element and the suppressing element are respectively connected to the two sets of communication wires. The input terminal of the receiver is connected to the two sets of communication wires, and the output terminal of the receiver is connected to the CAN controller.

[0009] In some embodiments, a time-controlled switch chip is provided on the branch line of the suppression element, and the time-controlled switch chip is used to activate or disable the suppression element.

[0010] In some embodiments, the resistor is an adjustable resistor.

[0011] In some embodiments, the resistors are integrated within the transceiver's integrated motherboard.

[0012] The CAN bus communication circuit and system provided in the embodiments of this application, through the above architecture, eliminate the need for dedicated node pairs containing terminating resistor lines that couple at least two buses together in the differential bus network. Furthermore, compared to traditional CAN circuit frameworks, signal transmission is more stable and efficient. The CAN bus communication circuit and system provided in the embodiments of this application effectively solve the problem that when a remote bus line fails or breaks, the terminating resistor becomes ineffective, thereby changing the bus impedance and causing interference to the entire bus communication due to a bus fault. Attached Figure Description

[0013] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 This is a schematic diagram of the CAN bus communication circuit in related technologies;

[0015] Figure 2 This is a schematic diagram of a CAN bus communication circuit provided in an embodiment of this application;

[0016] Figure 3 This is a schematic diagram of the transceiver provided in an embodiment of this application;

[0017] Figure 4 This is a comparison diagram of the differential signal of a conventional circuit and the differential signal of the CAN bus communication circuit provided in the embodiments of this application. Detailed Implementation

[0018] The preferred embodiments of this application will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are merely some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection claimed in this application.

[0019] The terms "first," "second," and similar words used in this application do not indicate any order, quantity, or importance, but are merely used to distinguish different parts. Words such as "including" or "contains" mean that the element preceding the word encompasses the element listed after it, and do not exclude the possibility of encompassing other elements as well. Terms such as "above," "below," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, this relative positional relationship may also change accordingly.

[0020] like Figures 1-4 As shown, according to the first aspect of this application, an embodiment of this application provides a CAN bus communication circuit, including: a twisted pair bus, a transceiver, and a CAN controller. The transceiver is connected to two branches of the twisted pair bus through two sets of communication wires. A resistor is provided between the two sets of communication wires. The transceiver includes a transmitter and a receiver, both of which are connected to the CAN controller. The transmitter includes a transmitting element and a suppressing element, both of which are connected to the output terminal of the CAN controller. The output terminals of the transmitting element and the suppressing element are respectively connected to the two sets of communication wires. The input terminal of the receiver is connected to the two sets of communication wires, and the output terminal of the receiver is connected to the CAN controller.

[0021] In a CAN bus communication system, the transceiver includes a transmitter 101 and a receiver 102. The transmitter 101 converts the digital data stream into a differential analog signal that can be transmitted via the bus; the receiver 102 is configured to convert the differential analog signal back into a digital data stream. The digital data is received by a CAN controller 103 based on the CAN communication protocol, which implements the protocol rules for sending and receiving data between nodes.

[0022] In the CAN bus communication circuit of this embodiment, the transmitter 101 includes a transmitting element 1011, which increases the potential difference between the twisted-pair buses to the first differential voltage stage (e.g., Figure 4 The differential high level of the B curve) and maintain the first differential stage, the suppression element 1012 is provided, and the potential difference between the twisted pair buses is reduced to the second differential voltage stage (such as the differential high level of the B curve) and maintained. Figure 4 (Differential low level of the B curve). The suppression element 1012 can selectively activate the resistor 104 to reduce the potential difference between the twisted-pair buses. Resistors 104 are provided at the output of the transmitter 101 on both sets of communication lines to maintain the second differential voltage phase. Actively driving the bus potential difference towards the second differential voltage phase using the suppression element 1012 provides a sharper transition between the first and second differential voltage phases. The suppression element 1012 has a controllable switching function so that it can be switched on and activated when the signal needs to transition from the first differential voltage phase to the second differential voltage phase. Resistors 104 can release residual energy or other voltage interference from the bus to maintain the second differential voltage phase.

[0023] Figure 4 A timing diagram showing the voltage variation of the transmitted signal over time at curve A is shown. The bus differential voltages on the two buses are shown on curve B. The digital received signal, which can be obtained from the differential signal at curve B, is shown on curve C. Dashed lines represent conventional circuit signals without the use of suppression element 1012, and solid lines represent signals with the use of suppression element 1012. Figure 4 It can be seen that after using the suppression element 1012, since the suppression element 1012 can actively drive the bus to obtain a lower potential difference, the change from the first differential state to the second differential state is relatively fast, while it is slower when not used. As can be seen from the C curve, it takes longer to receive the digital signal from the differential signal of the B curve. Therefore, the signal processing and transmission of this structure are more stable and efficient.

[0024] The suppression element 1012 includes a switch controller coupled to the suppression element 1012. The switch controller can be configured to activate the suppression element 1012 (from a disabled or low-power state) when a differential signal needs to transition from a first differential state to a second differential state. The switch controller is configured to receive digital transmission signals via an output branch line and is configured to activate the suppression element 1012 when a transition between a first logic level and a second logic level in the digital transmission signal is detected, such as a transition from logic low to logic high. This requires a transition from a first differential state to a second differential state. The activation of the suppression element 1012 can be performed for a predetermined time. Activation within the predetermined time allows the differential signal to be applied to the bus. At the end of the predetermined time, the switch controller is configured to deactivate the suppression element 1012 until the next transition between logic states in the digital transmission signal that requires a transition from the first differential state to the second differential state. The predetermined time should be less than the bit time of the logic level and less than the time required for the resistor 104 to dissipate energy from the bus. In some embodiments, a time-controlled switch chip 1113 can be configured on the branch line of the suppression element 1012 to activate or deactivate the suppression element 1012. In practice, the above functions are achieved by configuring the time-controlled switch chip 1113.

[0025] like Figure 2 As shown, in this communication circuit framework, resistors 104 are used between the bus terminals connected in each node to perform the function of a termination resistor at each end of the differential bus defined by the CAN protocol. Because resistors 104 drain energy from the bus, they work in conjunction with suppression element 1012 from the first differential phase to the second differential voltage phase. Therefore, when suppression element 1012 is activated, it effectively promotes the reduction of the voltage difference between the twisted-pair buses. Once suppression element 1012 is deactivated, resistors 104 on the two sets of communication lines on each transceiver will continue to act, consuming any energy from the bus to maintain the second differential phase. With this structure, the CAN communication circuit architecture does not involve dedicated node pairs containing termination resistor lines that couple at least two buses together.

[0026] In some embodiments, resistor 104 is an adjustable resistor, which allows its value to be changed to accommodate the number of nodes to be installed in the network, thereby ensuring normal communication between the various CAN nodes. In some embodiments, the resistor may be integrated into the transceiver's integrated motherboard to increase integration.

[0027] According to a second aspect of this application, an embodiment of this application provides a communication system, which includes a CAN bus communication circuit. The CAN bus communication circuit includes a twisted-pair bus, a transceiver, and a CAN controller. The transceiver is connected to two branches of the twisted-pair bus via two sets of communication wires. A resistor is provided between the two sets of communication wires. The transceiver includes a transmitter and a receiver, both of which are connected to the CAN controller. The transmitter includes a transmitting element and a suppressing element, both of which are connected to the output terminal of the CAN controller. The output terminals of the transmitting element and the suppressing element are respectively connected to the two sets of communication wires. The input terminal of the receiver is connected to the two sets of communication wires, and the output terminal of the receiver is connected to the CAN controller.

[0028] In some embodiments, a time-controlled switch chip is provided on the branch line of the suppression element, and the time-controlled switch chip is used to activate or disable the suppression element.

[0029] In some embodiments, the resistor is an adjustable resistor.

[0030] In some embodiments, the resistors are integrated within the transceiver's integrated motherboard.

[0031] This invention can effectively solve the problem that when a remote bus line is faulty or broken, the set terminating resistor becomes ineffective, thereby changing the bus impedance and causing the entire bus communication to be interfered with by a bus fault. When using this structure for the CAN communication circuit architecture, the differential bus network involved does not have dedicated node pairs containing terminating resistor lines that couple at least two buses together. At the same time, compared with the traditional CAN circuit framework, the signal transmission of this structure is more stable and efficient.

[0032] Based on the various embodiments of this application described above, in the absence of explicit denial or conflict, the technical features of one embodiment may be advantageously combined with one or more other embodiments.

[0033] While specific embodiments of this application have been described in detail by way of examples, those skilled in the art should understand that the above examples are for illustrative purposes only and are not intended to limit the scope of this application. Those skilled in the art should understand that modifications can be made to the above embodiments or equivalent substitutions can be made to some technical features without departing from the scope and spirit of this application. The scope of this application is defined by the appended claims.

Claims

1. A CAN bus communication circuit, characterized in that, include: The transceiver includes a twisted-pair bus, a transceiver, and a CAN controller. The transceiver is connected to two branches of the twisted-pair bus via two sets of communication wires. A resistor is installed between the two sets of communication wires. The transceiver includes a transmitter and a receiver, both of which are connected to the CAN controller. The transmitter includes a transmitting element and a suppressing element, both of which are connected to the output of the CAN controller. The outputs of the transmitting element and the suppressing element are respectively connected to the two sets of communication wires. The input of the receiver is connected to the two sets of communication wires, and the output of the receiver is connected to the CAN controller.

2. The CAN bus communication circuit according to claim 1, characterized in that, A time-controlled switch chip is provided on the branch line of the suppression element, and the time-controlled switch chip is used to activate or disable the suppression element.

3. The CAN bus communication circuit according to claim 1, characterized in that, The resistor is an adjustable resistor.

4. The CAN bus communication circuit according to claim 1, characterized in that, The resistor is integrated into the transceiver's integrated mainboard.

5. A communication system, characterized in that, The system includes a CAN bus communication circuit, comprising a twisted-pair bus, a transceiver, and a CAN controller. The transceiver is connected to two branches of the twisted-pair bus via two sets of communication wires, with a resistor between the two sets of communication wires. The transceiver includes a transmitter and a receiver, both of which are connected to the CAN controller. The transmitter includes a transmitting element and a suppressing element, both of which are connected to the output of the CAN controller. The outputs of the transmitting element and the suppressing element are respectively connected to the two sets of communication wires. The input of the receiver is connected to the two sets of communication wires, and the output of the receiver is connected to the CAN controller.

6. The communication system according to claim 5, characterized in that, A time-controlled switch chip is provided on the branch line of the suppression element, and the time-controlled switch chip is used to activate or disable the suppression element.

7. The communication system according to claim 5, characterized in that, The resistor is an adjustable resistor.

8. The communication system according to claim 5, characterized in that, The resistor is integrated into the transceiver's integrated mainboard.

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