Multi-CAN interface expansion circuit

Abstract

The utility model discloses a multi-CAN interface expansion circuit. The circuit comprises a picocontroller, a CAN transmit-receive controller circuit and N groups of CAN controller circuits. One end of the microcontroller is connected with one end of each group of CAN controller circuit through an IO pin, so that the CAN controller can be read and written by using the microcontroller; the other end of the CAN controller circuit is connected with one end of the CAN transceiving controller circuit; the other end of the CAN transceiving controller circuit is connected to a CAN bus of external equipment, so that data communication on the CAN bus can be processed; and the other end of the microcontroller is in circuit connection with the CAN transceiving controller. According to the invention, the number of the CAN interfaces can be increased, so that the problem that the number of the CAN interfaces of the microcontroller is insufficient can be effectively solved.

Description

Technical Field

[0001] This application relates to the field of electronic control, and particularly to a multi-CAN interface expansion circuit. Background Art

[0002] In the current design of embedded systems, although the CAN modules built into microcontrollers can provide basic data sending and receiving functions, the number of built-in CAN modules is limited, usually one or two interfaces; however, sometimes according to the development of project functions, it is required to expand multiple CAN interfaces for sending and receiving different data, so it is difficult to meet the requirements only with microcontrollers. Utility Model Content

[0003] Based on this, in view of the above technical problems, a multi-CAN interface expansion circuit is provided to solve the problem of insufficient CAN interface numbers when using a microcontroller with a built-in CAN module to implement data sending and receiving in the prior art.

[0004] A multi-CAN interface expansion circuit, the circuit includes: a microcontroller,

[0005] N + 1 groups of CAN transceiver controller circuits, N groups of CAN controller circuits;

[0006] The first output end of the microcontroller is respectively connected to one end of each group of CAN controller circuits through IO pins to realize reading and writing of the CAN controller by using the microcontroller; the N groups of CAN controller circuits are respectively connected to the N groups of CAN transceiver controller circuits one by one, and the output end of the controller circuit is connected to the input end of the transceiver controller circuit; the output end of the CAN transceiver controller circuit is connected to the CAN bus of an external device to realize processing of data communication on the CAN bus;

[0007] The second output end of the microcontroller is connected to the input end of the (N + 1)th transceiver controller circuit, and the output end of the (N + 1)th transceiver controller circuit is connected to the CAN bus of an external device.

[0008] In the above solution, optionally, N≥1.

[0009] In the above solution, optionally, the circuit further includes: N + 1 groups of isolation circuits;

[0010] The N groups of CAN controller circuits are respectively connected to the CAN transceiver controller circuits one by one through N groups of isolation circuits.

[0011] In the above solution, further optionally, the second output end of the microcontroller is connected to the input end of the (N + 1)th transceiver controller circuit through the (N + 1)th group of isolation circuits.

[0012] In the above solution, optionally, the circuit further includes a protection circuit, and the protection circuit is connected to the CAN bus of the external device.

[0013] In the above solution, further optionally, the protection circuit includes: resistor R4, resistor R5, resistor R10, capacitor C52, varistor T10, diodes T5 and T6;

[0014] The resistor R10, capacitor C52 and varistor T10 are connected in parallel in sequence. One end of resistor R4 is connected to one end of resistor R10, and one end of resistor R5 is connected to the other end of resistor R10; the other ends of resistor R4 and resistor R10 are connected to the CAN transceiver controller circuit; a node is set on the connection line of capacitor C52 and varistor T10, and a second branch is led out from the node to be connected to one end of diode T5; one end of diode T6 is connected to varistor T10, and the other end is connected to the other end of diode T5;

[0015] Both ends of the varistor T10 are connected to the CAN bus of the external device.

[0016] In the above solution, further optionally, the resistance values of resistor R4 and resistor R5 are 10 ohms, and the resistance value of resistor R10 is 120 ohms.

[0017] In the above solution, optionally, the chip model adopted in the CAN controller circuit is SJA1000.

[0018] In the above solution, optionally, the chip model adopted in the CAN transceiver controller circuit is PCA82C251.

[0019] In the above solution, further optionally, the chip model adopted in the isolation circuit is ADUM1201 dual-channel memory digital display isolator.

[0020] This application has at least the following beneficial effects:

[0021] In this application, the microcontroller is connected to the CAN controller circuit, and thus is connected to the CAN transceiver controller circuit through the CAN controller circuit, increasing the number of CAN interfaces. Therefore, it can effectively overcome the limitation of the insufficient number of CAN interfaces of the microcontroller. By flexibly expanding multiple CAN interfaces, the communication ability and adaptability of the system are enhanced, meeting the requirements for multiple CAN interfaces in complex application scenarios. At the same time, the reliability of the system and the convenience of maintenance are improved. Description of the Drawings

[0022] Figure 1 It is a connection schematic diagram of a multi-CAN interface expansion circuit provided by an embodiment of this application;

[0023] Figure 2 Schematic diagram of the CAN controller circuit provided by an embodiment of the present application;

[0024] Figure 3 Schematic diagram of the controller circuit provided by an embodiment of the present application;

[0025] Figure 4 Schematic diagram of the isolation circuit provided by an embodiment of the present application;

[0026] Figure 5 Schematic diagram of the CAN transceiver controller circuit provided by an embodiment of the present application;

[0027] Figure 6 Schematic diagram of the protection circuit provided by an embodiment of the present application. Detailed implementation manners

[0028] In order to make the objectives, technical solutions and advantages of the present application clearer and more understandable, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0029] In one embodiment, as Figure 1 shown, a multi-CAN interface expansion circuit, the circuit includes: a microcontroller,

[0030] N + 1 groups of CAN transceiver controller circuits, and N groups of CAN controller circuits;

[0031] The first output terminal of the microcontroller is respectively connected to one end of each group of CAN controller circuits through IO pins to realize reading and writing of the CAN controller by using the microcontroller; the N groups of CAN controller circuits are respectively connected to the N groups of CAN transceiver controller circuits one by one, and the output terminal of the controller circuit is connected to the input terminal of the transceiver controller circuit; the output terminal of the CAN transceiver controller circuit is connected to the CAN bus of the external device to realize processing of data communication on the CAN bus;

[0032] The second output terminal of the microcontroller is connected to the input terminal of the (N + 1)th transceiver controller circuit, and the output terminal of the (N + 1)th transceiver controller circuit is connected to the CAN bus of the external device.

[0033] Specifically, as Figure 2 shown is the schematic diagram of the microcontroller circuit, Figure 3It is a schematic diagram of the CAN controller circuit. A part of the IO of the microcontroller is used to control the CAN controller control interface. The microcontroller pins PC4, PD7, PD4, PD5, PC5, and PA7 are connected to the ALE / AS pin, CS pin, RD / E pin, WR pin, MODE pin, and RST pin of the CAN controller chip, respectively, to realize the reading and writing of the registers of the CAN controller by using the microcontroller.

[0034] In the above multi-CAN interface expansion circuit, the microcontroller is connected to the CAN controller circuit, and thus the CAN controller circuit is connected to the CAN transceiver controller circuit, increasing the number of CAN interfaces. Therefore, it can effectively overcome the limitation of the insufficient number of CAN interfaces of the microcontroller. By flexibly expanding multiple CAN interfaces, the communication ability and adaptability of the system are enhanced, meeting the requirements for multiple CAN interfaces in complex application scenarios. At the same time, the reliability of the system and the convenience of maintenance are improved.

[0035] In one embodiment, N≥1. Generally, the number of CAN transceiver controller circuits and CAN controller circuits is designed according to actual requirements.

[0036] In one embodiment, the circuit further includes: N + 1 groups of isolation circuits;

[0037] The N groups of CAN controller circuits are respectively connected to the CAN transceiver controller circuit one by one through N groups of isolation circuits.

[0038] Specifically, as Figure 4 shown is the schematic diagram of the isolation circuit. The chip used for the module U10 in the isolation circuit is the ADUM1201 dual-channel memory digital display isolator, which is used for electrical isolation between the CAN controller circuit and the CAN transceiver controller to achieve signal isolation and insulation. Pins 6 and 7 in U10 are the input CAN_RX and CAN_TX, respectively, and are connected to the RX and TX pins of the chip in the CAN controller circuit. Pins 2 and 3 in U10 are the output CAN_TX and CAN_RX, respectively, and are connected to the TXD and RXD pins of the CAN transceiver controller circuit chip.

[0039] The chip of the module U14 in the CAN transceiver controller circuit is the PCA82C251, a CAN controller chip, which is responsible for processing data communication on the CAN bus and receiving and sending messages. Pin 1 in U14 is the data output line TXD, pin 4 is the data input line RXD, and is connected to the bus line through the bus terminals CANH pin 7 and CANL pin 6 with differential receiving and sending capabilities. Pin 8 is for mode control, and the reference output voltage VREF pin 5 provides a rated output voltage of VCC / 2, which is the reference level for analog RXD input of the CAN controller.

[0040] In one embodiment, the second output terminal of the microcontroller is connected to the input terminal of the (N + 1)-th transceiver controller circuit through the (N + 1)-th group of isolation circuits.

[0041] In one embodiment, as Figure 5 shown, the circuit further includes a protection circuit, and the protection circuit is connected to the CAN bus of the external device.

[0042] In one embodiment, the protection circuit includes: resistor R4, resistor R5, resistor R10, capacitor C52, varistor T10, diodes T5 and T6;

[0043] The resistor R10, capacitor C52 and varistor T10 are connected in parallel in sequence. One end of the resistor R4 is connected to one end of the resistor R10, and one end of the resistor R5 is connected to the other end of the resistor R10; the other ends of the resistor R4 and the resistor R10 are connected to the CAN transceiver controller circuit; a node is set on the connection line of the capacitor C52 and the varistor T10, and a second branch is led out from the node and connected to one end of the diode T5; one end of the diode T6 is connected to the varistor T10, and the other end is connected to the other end of the diode T5;

[0044] Both ends of the varistor T10 are connected to the CAN bus of the external device.

[0045] In this embodiment, the protection circuit improves the reliability and stability of system communication. The resistor R10 is a terminal matching resistor, which is used to match the bus characteristic impedance and improve the signal quality. The resistors R4 and R5 can prevent the current caused by short circuit or overload from damaging the interface circuit. The functions of the TVS diodes T5 and T6 are to absorb and suppress the overvoltage caused by electrostatic discharge and protect the CAN bus driver and receiver.

[0046] In one embodiment, the resistance values of the resistor R4 and the resistor R5 are 10 ohms, and the resistance value of the resistor R10 is 120 ohms.

[0047] In one embodiment, the chip model adopted in the CAN controller circuit is SJA1000.

[0048] In one embodiment, the chip model adopted in the CAN transceiver controller circuit is PCA82C251.

[0049] In one embodiment, the chip model adopted in the isolation circuit is ADUM1201 dual-channel memory digital isolator.

[0050] The utility model solves the problem of insufficient number of CANs provided by the microcontroller, has simple and reliable hardware connection, reduced system cost, and is easy to transplant; improves system stability and reliability, and reduces system energy consumption.

[0051] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0052] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the utility model patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.

Claims

1. A multi-CAN interface expansion circuit, characterized in that: The circuit comprises: a microcontroller, N+1 groups of CAN transceiver controller circuits, and N groups of CAN controller circuits; The first output end of the microcontroller is connected to one end of each group of CAN controller circuits through IO pins, so as to realize reading and writing the CAN controller by using the microcontroller; the N groups of CAN controller circuits are connected to the N groups of CAN transceiver controller circuits one by one, and the output end of the controller circuit is connected to the input end of the transceiver controller circuit; the output end of the CAN transceiver controller circuit is connected to the CAN bus of the external device, so as to realize processing of data communication on the CAN bus; The second output end of the microcontroller is connected to the input end of the N+1th transceiver controller circuit, and the output end of the N+1th transceiver controller circuit is connected to the CAN bus of the external device.

2. The multi-CAN interface expansion circuit according to claim 1, characterized in that: N≥1。 3. The multi-CAN interface expansion circuit according to claim 1, characterized in that: The circuit further comprises: N+1 groups of isolation circuits; The N groups of CAN controller circuits are connected one by one to the CAN transceiver controller circuits through N groups of isolation circuits respectively.

4. The multi-CAN interface expansion circuit according to claim 3, characterized in that: The second output end of the microcontroller is connected to the input end of the N+1th transceiver controller circuit through the N+1th isolation circuit.

5. The multi-CAN interface expansion circuit according to claim 1, characterized in that: The circuit further comprises a protection circuit, and the protection circuit is connected to the CAN bus of the external device.

6. The multi-CAN interface expansion circuit according to claim 5, characterized in that: The protection circuit includes: a resistor R4, a resistor R5, a resistor R10, a capacitor C52, a varistor T10, and diodes T5 and T6; The resistor R10, the capacitor C52 and the variable resistor T10 are connected in parallel in sequence, one end of the resistor R4 is connected to one end of the resistor R10, and one end of the resistor R5 is connected to the other end of the resistor R10; the other ends of the resistor R4 and the resistor R10 are connected to the CAN transceiver controller circuit; a node is set on the connection line between the capacitor C52 and the variable resistor T10, and a second branch is drawn from the node and connected to one end of the diode T5; one end of the diode T6 is connected to the variable resistor T10, and the other end is connected to the other end of the diode T5; Both ends of the variable resistor T10 are connected to the CAN bus of the external device.

7. The multi-CAN interface expansion circuit according to claim 6, characterized in that: The resistance values ​​of the resistor R4 and the resistor R5 are 10 ohms, and the resistance value of the resistor R10 is 120 ohms.

8. The multi-CAN interface expansion circuit according to claim 1, characterized in that: The chip model used in the CAN controller circuit is SJA1000.

9. The multi-CAN interface expansion circuit according to claim 1, characterized in that: The chip model used in the CAN transceiver controller circuit is PCA82C251.

10. The multi-CAN interface expansion circuit according to claim 3, characterized in that: The chip model used in the isolation circuit is ADUM1201 dual-channel memory digital display isolator.

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