CAN communication circuit and CAN communication equipment

Abstract

The utility model provides a CAN communication circuit and CAN communication equipment, the circuit comprises a switch control circuit, a communication switch circuit and a multiplexing control circuit, the communication switch circuit comprises a first field effect transistor, a second field effect transistor and a voltage stabilizing resistor, and the multiplexing control circuit comprises a ninth resistor, a tenth resistor, a first triode and a universal diode. When the CAN communication circuit carries out communication, the control unit enables a communication signal, the first field effect transistor and the second field effect transistor are conducted through the switch control circuit, meanwhile, the control unit enables a detection signal high level and turns off the first triode, and interference of a multiplexing circuit under communication is avoided; when other functions are multiplexed, the control unit pulls the communication signal and the detection signal to a low level, so that the first field effect transistor and the second field effect transistor are switched off and the first triode is switched on, and multiplexing operation is carried out. According to the circuit, additional physical interfaces are not needed, and the structural design difficulty is reduced.

Description

Technical Field

[0001] The present disclosure relates to the technical field of CAN communication and multiplexing, and in particular to a CAN communication circuit and a CAN communication device. Background Art

[0002] With the development of communication technology, CAN (Controller Area Network) communication, as a stable, fast and efficient communication protocol, can support high-speed data transmission between multiple nodes and is suitable for systems with high real-time performance and high reliability. This communication has been widely used in various fields, especially in the communication between various components in automobiles and in industrial system control.

[0003] At present, the CAN bus consists of two lines, high-speed CAN_H and low-speed CAN_L, which are generally only used to transmit data. If multiplexing functions are required, especially for the signal insertion and recognition function outside the system, it is often necessary to add an additional physical interface structure as signal access, which greatly increases the difficulty and time cost of structural design when the structural space is limited. Therefore, it is very necessary to design a communication circuit that is compatible with multiplexing other functions. Utility Model Content

[0004] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a CAN communication circuit and a CAN communication device that can multiplex other functions without adding an additional physical interface.

[0005] The purpose of this disclosure is achieved through the following technical solutions:

[0006] A CAN communication circuit, comprising:

[0007] A switch control circuit, wherein the power connection terminal of the switch control circuit is used to connect to a DC power supply, and the controlled terminal of the switch control circuit is used to connect to a communication enable terminal of a control unit;

[0008] A communication switch circuit, comprising a first field effect transistor, a second field effect transistor and a voltage-stabilizing resistor, wherein a first end of the voltage-stabilizing resistor is connected to an output end of the switch control circuit, a second end of the voltage-stabilizing resistor is respectively connected to a control end of the first field effect transistor and a control end of the second field effect transistor, a first end of the first field effect transistor is used to connect to a high-speed communication end, a second end of the first field effect transistor is connected to a first end of the second field effect transistor, and a second end of the second field effect transistor is used to connect to two high-speed communication ends;

[0009] A multiplexing control circuit includes a ninth resistor, a tenth resistor, a first transistor and a universal diode, wherein a first end of the first transistor is connected to a reference power supply, a control end of the first transistor is connected to an output control end of a control unit through the ninth resistor, a second end of the first transistor is connected to a first end of the tenth resistor, a second end of the tenth resistor is connected to an anode of the universal diode and is also used to connect to an input end of the control unit, and a cathode of the universal diode is connected to a second end of the second field effect transistor.

[0010] In one embodiment, the voltage-stabilizing resistor includes a fifth resistor and a seventh resistor, the output end of the switch control circuit is respectively connected to the first end of the fifth resistor and the first end of the seventh resistor, the second end of the fifth resistor is connected to the control end of the first field effect transistor, and the second end of the seventh resistor is connected to the control end of the second field effect transistor.

[0011] In one embodiment, the voltage-stabilizing resistor also includes a sixth resistor, a first end of the sixth resistor is respectively connected to the first end of the fifth resistor and the first end of the seventh resistor, and a second end of the sixth resistor is respectively connected to the second end of the first field effect transistor and the first end of the second field effect transistor.

[0012] In one embodiment, at least one of the fifth resistor, the sixth resistor and the seventh resistor is a variable resistor.

[0013] In one embodiment, the multiplexing control circuit further includes an eighth resistor, a first end of the eighth resistor is connected to the first end of the first transistor, and a second end of the eighth resistor is connected to the control end of the first transistor.

[0014] In one embodiment, at least one of the eighth resistor and the ninth resistor is a variable resistor.

[0015] In one embodiment, the switch control circuit includes a second transistor, a third transistor, a second resistor and a third resistor, the first end of the third transistor is used to connect to a DC power supply, the second end of the third transistor is connected to the first end of the voltage-stabilizing resistor, the control end of the third transistor is connected to the first end of the second transistor through the second resistor, the second end of the second transistor is grounded, and the control end of the second transistor is connected to the communication enable end of the control unit through the third resistor.

[0016] In one embodiment, the switch control circuit further includes a first resistor, a first end of the first resistor is connected to the first end of the third transistor, and a second end of the first resistor is connected to the control end of the third transistor.

[0017] In one embodiment, the switch control circuit further includes a fourth resistor, a first end of the fourth resistor is connected to the control end of the second transistor, and a second end of the fourth resistor is connected to the second end of the second transistor.

[0018] A CAN communication device comprises the CAN communication circuit described in any one of the above embodiments.

[0019] Compared with the prior art, the present invention has at least the following advantages:

[0020] When the CAN communication circuit is communicating, the control unit enables the communication signal, turns on the first field effect tube and the second field effect tube through the switch control circuit, and at the same time enables the detection signal to be high level, turns off the first transistor, and avoids interference from the multiplexing control circuit during communication; when the CAN communication circuit multiplexes other functions, the control unit pulls the communication signal and the detection signal to a low level, turns off the first field effect tube and the second field effect tube, and turns on the first transistor for multiplexing operation. This circuit can realize multiplexing of other functions without adding additional physical interfaces, reducing the difficulty of structural design. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present disclosure and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 4 is a circuit diagram of a CAN communication circuit in one embodiment.

[0023] Description of the drawings: 10, CAN communication circuit; 100, switch control circuit; 200, communication switch circuit; 300, multiplexing control circuit; R1, voltage-stabilizing resistor; RF1, first resistor; RF2, second resistor; RF3, third resistor; RF4, fourth resistor; RF5, fifth resistor; RF6, sixth resistor; RF7, seventh resistor; RK1, eighth resistor; RK2, ninth resistor; RK3, tenth resistor; QK1, first transistor; QF2, second transistor; QF1, third transistor; MF1, first field-effect transistor; MF2, second field-effect transistor; DK1, general diode. DETAILED DESCRIPTION

[0024] In order to facilitate the understanding of the present disclosure, the present disclosure will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present disclosure are given in the drawings. However, the present disclosure can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present disclosure more thoroughly and comprehensively understood.

[0025] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only and do not represent the only implementation method.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present disclosure. The terms used herein in the specification of the present disclosure are only for the purpose of describing specific embodiments and are not intended to limit the present disclosure. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0027] In order to better understand the technical solutions and beneficial effects of the present invention, the present invention is further described in detail below in conjunction with specific embodiments:

[0028] See also Figure 1 , which is a CAN communication circuit 10 according to an embodiment of the present invention, includes a switch control circuit 100 , a communication switch circuit 200 and a multiplexing control circuit 300 .

[0029] The power connection terminal of the switch control circuit 100 is used to connect to the DC power supply VDD, and the controlled terminal of the switch control circuit 100 is used to connect to the communication enable terminal of the control unit.

[0030] In this embodiment, the switch control circuit 100 includes a second transistor QF2, a third transistor QF1, a second resistor RF2 and a third resistor RF3. The first end of the third transistor QF1 is used to connect to a DC power supply, the control end of the third transistor QF1 is connected to the first end of the second transistor QF2 through the second resistor RF2, the second end of the second transistor QF2 is grounded, and the control end of the second transistor QF2 is connected to the communication enable end of the control unit through the third resistor RF3.

[0031] The communication switch circuit 200 includes a first field effect transistor MF1, a second field effect transistor MF2 and a voltage-stabilizing resistor R1. The first end of the voltage-stabilizing resistor R1 is connected to the output end of the switch control circuit 100, that is, the second end of the third transistor QF1. The second end of the voltage-stabilizing resistor R1 is respectively connected to the control end of the first field effect transistor MF1 and the control end of the second field effect transistor MF2. The first end of the first field effect transistor MF1 is used to connect to the high-speed communication terminal CAN_H1, the second end of the first field effect transistor MF1 is connected to the first end of the second field effect transistor MF2, and the second end of the second field effect transistor MF2 is used to connect to the high-speed communication terminal CAN_H2.

[0032] The multiplexing control circuit 300 includes a ninth resistor RK2, a tenth resistor RK3, a first transistor QK1 and a universal diode DK1. The first end of the first transistor QK1 is connected to a reference power supply VCC, the control end of the first transistor QK1 is connected to the output control end of the control unit through the ninth resistor RK2, the second end of the first transistor QK1 is connected to the first end of the tenth resistor RK3, the second end of the tenth resistor RK3 is connected to the anode of the universal diode DK1, and is also used to connect to the input end of the control unit, and the cathode of the universal diode DK1 is connected to the second end of the second field effect transistor MF2.

[0033] In this embodiment, when the CAN communication circuit 10 is communicating, the control unit enables the communication signal, turns on the first field effect transistor MF1 and the second field effect transistor MF2 through the switch control circuit 100, and at the same time enables the detection signal to be high level, turns off the first transistor QK1, and avoids interference from the multiplexing control circuit 300 during communication; when the CAN communication circuit 10 multiplexes other functions, the control unit pulls the communication signal and the detection signal to a low level, turns off the first field effect transistor MF1 and the second field effect transistor MF2, and turns on the first transistor QK1 to perform multiplexing operations. This circuit can realize multiplexing of other functions without adding additional physical interfaces, reducing the difficulty of structural design.

[0034] It can be understood that when CANs need to communicate with each other, it is necessary to ensure that the low-speed CAN_L and high-speed CAN_H of each node are in the on state, and the control unit needs to enable the communication signal ON_CANH and the control signal ON_Charger_Check. At this time, the communication signal ON_CANH pulls the control end of the second transistor QF2 to a high level, thereby turning it on. Subsequently, the control end of the third transistor QF1 is pulled to a low level and turned on. The first end and the second end of the third transistor QF1 are at a high level to turn on the first field effect transistor MF1 and the second field effect transistor MF2. At the same time, the control signal ON_Charger_Check pulls the control end of the first transistor QK1 to a high level to turn it off. At this time, the multiplexing control circuit 300 is in a disconnected state. As long as the communication signal ON_CANH and the control signal ON_Charger_Check are both high levels, the CAN communication can be guaranteed to proceed normally. It should be noted that when CAN is communicating with each other, if the control signal ON_Charger_Check is in a low level state, the first transistor QK1 will be turned on. At this time, the current of the reference power supply is connected to the communication terminal CAN_H2 through the first transistor QK1, the tenth resistor RK3 and the universal diode DK1 in sequence. The above situation will cause the CAN communication to be interfered by the reference power supply signal. Therefore, in order to ensure normal CAN communication, the control signal ON_Charger_Check needs to be pulled to a high level. At the same time, in the state of the universal diode DK1, the current output from the second field effect transistor MF2 will not pass through the input end of the control unit, avoiding signal interference at the input end of the control unit.

[0035] When the communication terminal CAN_H2 is multiplexed with other functions such as signal insertion identification function detection, the control unit pulls the communication signal ON_CANH and the control signal ON_Charger_Check to a low level. The communication signal ON_CANH in the low level state disconnects the entire switch control circuit 100, and then the control terminals of the first field effect transistor MF1 and the second field effect transistor MF2 are both low level, thereby shutting down and stopping the CAN communication operation. The control signal ON_Charger_Check in the low level state pulls the control terminal of the first transistor QK1 to a low level to turn on, and then the input end of the control unit receives the high level signal CHARGE_ON. When the communication terminal CAN_H2 is connected to the common terminal GND, the control signal ON_Charger_Check level is pulled down to achieve level conversion for the control unit to identify, and finally the control unit receives this signal and determines that the signal insertion is successful. Of course, the multiplexing control circuit 300 is not limited to the application of the signal insertion identification function, but can also be applied to other aspects, and only functional adjustments are required, without the need to add other physical interfaces. During this period, the design of the universal diode DK1 can prevent the control unit and the first transistor QK1 from being damaged due to the high-speed communication terminal CAN_H2 being mistakenly connected to high voltage, thereby ensuring the normal operation of the multiplexing control circuit 300.

[0036] In this embodiment, the first transistor QK1 and the third transistor QF1 are both PNP transistors, the first end of the first transistor QK1 is an emitter, the second end is a collector, and the control end is a base; the first end of the third transistor QF1 is an emitter, the second end is a collector, and the control end is a base; the second transistor QF2 is an NPN transistor, the first end is a collector, the second end is an emitter, and the control end is a base; the first field effect transistor MF1 and the second field effect transistor MF2 are both N-type MOS transistors, the first end of the first field effect transistor MF1 is a drain, the second end is a source, and the control end is a gate; the first end of the second field effect transistor MF2 is a source, the second end is a drain, and the control end is a gate. The first field effect transistor MF1 and the second field effect transistor MF2 are arranged back to back, so that when the communication end CAN_H1 and the communication end CAN_H2 are disconnected, they do not interfere with each other and affect the multiplexing function.

[0037] In one embodiment, the voltage-stabilizing resistor R1 includes a fifth resistor RF5 and a seventh resistor RF7, the output end of the switch control circuit 100 is connected to the first end of the fifth resistor RF5 and the first end of the seventh resistor RF7 respectively, the second end of the fifth resistor RF5 is connected to the control end of the first field effect transistor MF1, and the second end of the seventh resistor RF7 is connected to the control end of the second field effect transistor MF2. In this embodiment, the first end of the fifth resistor RF5 and the first end of the seventh resistor RF7 are both connected to the second end of the third triode QF1, so that the fifth resistor RF5 and the seventh resistor RF7 are connected in parallel. The fifth resistor RF5 is connected in series to the control end of the first field effect transistor MF1 to protect the first field effect transistor MF1; the seventh resistor RF7 is connected in series to the control end of the second field effect transistor MF2 to protect the second field effect transistor MF2.

[0038] In one embodiment, the voltage-stabilizing resistor R1 further includes a sixth resistor RF6, a first end of the sixth resistor RF6 is respectively connected to a first end of the fifth resistor RF5 and a first end of the seventh resistor RF7, and a second end of the sixth resistor RF6 is respectively connected to a second end of the first field effect transistor MF1 and a first end of the second field effect transistor MF2. It can be understood that the sixth resistor RF6 is connected in parallel with the fifth resistor RF5 and the seventh resistor RF7 to further protect the first field effect transistor MF1 and the second field effect transistor MF2 to avoid the situation where the current is too large to break down the first field effect transistor MF1 and the second field effect transistor MF2.

[0039] Further, at least one of the fifth resistor RF5, the sixth resistor RF6 and the seventh resistor RF7 is a variable resistor. In the present embodiment, when one, two or three of the fifth resistor RF5, the sixth resistor RF6 and the seventh resistor RF7 are variable resistors, the resistance ratio of the fifth resistor RF5, the sixth resistor RF6 and the seventh resistor RF7 can be adjusted by adjusting the resistance value of one, two or three of the fifth resistor RF5, the sixth resistor RF6 and the seventh resistor RF7, thereby adjusting the conduction condition of one or two of the first field effect transistor MF1 and the second field effect transistor MF2, so as to adapt to more models of the first field effect transistor MF1 or the second field effect transistor MF2, that is, N-type MOS tubes.

[0040] In one embodiment, the multiplexing control circuit 300 further includes an eighth resistor RK1, a first end of the eighth resistor RK1 is connected to the first end of the first triode QK1, and a second end of the eighth resistor RK1 is connected to the control end of the first triode QK1. It can be understood that the eighth resistor RK1 is connected between the first end and the control end of the first triode QK1 to further protect the first triode QK1 and avoid the first triode QK1 from being broken down. At the same time, the eighth resistor RK1 can ensure that the first triode QK1 is not disturbed and is in a cut-off state when the control end of the first triode QK1 is suspended.

[0041] In one embodiment, at least one of the eighth resistor RK1 and the ninth resistor RK2 is a variable resistor. In this embodiment, when one or both of the eighth resistor RK1 and the ninth resistor RK2 are variable resistors, the resistance ratio of the eighth resistor RK1 and the ninth resistor RK2 can be adjusted by adjusting the resistance value of one or both of the eighth resistor RK1 and the ninth resistor RK2, thereby adjusting the conduction condition of the first transistor QK1 to adapt to more models of the first transistor QK1.

[0042] In one embodiment, the switch control circuit 100 further includes a first resistor RF1, a first end of the first resistor RF1 is connected to a first end of the third transistor QF1, and a second end of the first resistor RF1 is connected to a control end of the third transistor QF1. It can be understood that the first resistor RF1 is connected between the first end and the control end of the third transistor QF1 to further protect the third transistor QF1 and avoid the third transistor QF1 from being broken down. At the same time, when the second transistor QF2 is turned on, the current of the DC power supply is grounded through the first resistor RF1, the second resistor RF2 and the second transistor QF2, which can ensure that the control end of the third transistor QF1 is at a low level, thereby normally turning on the third transistor QF1.

[0043] In one embodiment, the switch control circuit 100 further includes a fourth resistor RF4, a first end of the fourth resistor RF4 is connected to the control end of the second transistor QF2, and a second end of the fourth resistor RF4 is connected to the second end of the second transistor QF2. It can be understood that when the control unit enables the communication signal ON_CANH, the current is grounded through the third resistor RF3 and the fourth resistor RF4 in sequence, the third resistor RF3 and the fourth resistor RF4 are divided and a voltage drop is generated in the fourth resistor RF4, and the voltage drop can turn on the second transistor QF2. Further, at least one of the third resistor RF3 and the fourth resistor RF4 is a variable resistor. In this embodiment, when one or both of the third resistor RF3 and the fourth resistor RF4 are variable resistors, the resistance value of one or both of the third resistor RF3 and the fourth resistor RF4 can be adjusted to adjust the resistance ratio of the third resistor RF3 to the fourth resistor RF4, thereby adjusting the conduction condition of the second transistor QF2 to adapt to more models of the second transistor QF2.

[0044] The present disclosure further provides a CAN communication device, comprising the CAN communication circuit 10 of any one of the above embodiments.

[0045] Compared with the prior art, the present invention has at least the following advantages:

[0046] When the CAN communication circuit 10 is communicating, the control unit enables the communication signal, turns on the first field effect transistor MF1 and the second field effect transistor MF2 through the switch control circuit 100, and at the same time enables the detection signal to be high level, turns off the first transistor QK1, and avoids interference from the multiplexing control circuit 300 during communication; when the CAN communication circuit 10 multiplexes other functions, the control unit pulls the communication signal and the detection signal to a low level, turns off the first field effect transistor MF1 and the second field effect transistor MF2, and turns on the first transistor QK1 to perform multiplexing operations. The circuit can realize multiplexing of other functions without adding additional physical interfaces, reducing the difficulty of structural design.

[0047] The above-mentioned embodiments only express several implementation methods of the present disclosure, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the disclosed 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 disclosure, and these all belong to the protection scope of the present disclosure. Therefore, the protection scope of the disclosed patent shall be subject to the attached claims.

Claims

1. A CAN communication circuit, characterized in that: include: A switch control circuit, wherein the power connection terminal of the switch control circuit is used to connect to a DC power supply, and the controlled terminal of the switch control circuit is used to connect to a communication enable terminal of a control unit; A communication switch circuit, comprising a first field effect transistor, a second field effect transistor and a voltage-stabilizing resistor, wherein a first end of the voltage-stabilizing resistor is connected to an output end of the switch control circuit, a second end of the voltage-stabilizing resistor is respectively connected to a control end of the first field effect transistor and a control end of the second field effect transistor, a first end of the first field effect transistor is used to connect to a high-speed communication end, a second end of the first field effect transistor is connected to a first end of the second field effect transistor, and a second end of the second field effect transistor is used to connect to two high-speed communication ends; A multiplexing control circuit includes a ninth resistor, a tenth resistor, a first transistor and a universal diode, wherein a first end of the first transistor is connected to a reference power supply, a control end of the first transistor is connected to an output control end of a control unit through the ninth resistor, a second end of the first transistor is connected to a first end of the tenth resistor, a second end of the tenth resistor is connected to an anode of the universal diode and is also used to connect to an input end of the control unit, and a cathode of the universal diode is connected to a second end of the second field effect transistor.

2. The CAN communication circuit according to claim 1, characterized in that: The voltage-stabilizing resistor includes a fifth resistor and a seventh resistor. The output end of the switch control circuit is respectively connected to the first end of the fifth resistor and the first end of the seventh resistor. The second end of the fifth resistor is connected to the control end of the first field effect transistor. The second end of the seventh resistor is connected to the control end of the second field effect transistor.

3. The CAN communication circuit according to claim 2, characterized in that: The voltage-stabilizing resistor also includes a sixth resistor, a first end of the sixth resistor is respectively connected to the first end of the fifth resistor and the first end of the seventh resistor, and a second end of the sixth resistor is respectively connected to the second end of the first field effect transistor and the first end of the second field effect transistor.

4. The CAN communication circuit according to claim 3, characterized in that: At least one of the fifth resistor, the sixth resistor, and the seventh resistor is a variable resistor.

5. The CAN communication circuit according to claim 1, characterized in that: The multiplexing control circuit further includes an eighth resistor, a first end of the eighth resistor is connected to the first end of the first transistor, and a second end of the eighth resistor is connected to the control end of the first transistor.

6. The CAN communication circuit according to claim 5, characterized in that: At least one of the eighth resistor and the ninth resistor is a variable resistor.

7. The CAN communication circuit according to claim 1, characterized in that: The switch control circuit includes a second triode, a third triode, a second resistor and a third resistor, the first end of the third triode is used to connect to a DC power supply, the second end of the third triode is connected to the first end of the voltage-stabilizing resistor, the control end of the third triode is connected to the first end of the second triode through the second resistor, the second end of the second triode is grounded, and the control end of the second triode is connected to the communication enable end of the control unit through the third resistor.

8. The CAN communication circuit according to claim 7, characterized in that: The switch control circuit further includes a first resistor, a first end of the first resistor is connected to the first end of the third transistor, and a second end of the first resistor is connected to the control end of the third transistor.

9. The CAN communication circuit according to claim 7, characterized in that: The switch control circuit further includes a fourth resistor, a first end of the fourth resistor is connected to the control end of the second transistor, and a second end of the fourth resistor is connected to the second end of the second transistor.

10. A CAN communication device, characterized in that: The CAN communication circuit comprises the CAN communication circuit described in any one of claims 1 to 9.

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