Bus communication circuit and electronic product

Abstract

The utility model discloses a bus communication circuit and electronic product, the input end connection power supply of first opto -coupler light emitting end, the output end connection bus port, the input end connection first direct current power of light receiving end, the output end connection first switch tube control end of light receiving end, first switch tube switch path connects the cathode of first diode, the anode connection first control unit receiving end, and through first pull -up resistance connection first direct current power, first switch tube switch path connects second control unit receiving end, and through second pull -up resistance connection second direct current power, first direct current power voltage is less than second direct current power, the input end of second opto -coupler light emitting end through second switch tube connection first direct current power, second switch tube control end connection two control units'sending end, the input end connection power supply of light receiving end, the output end connection third switch tube control end, third switch tube switch path connection bus port. The utility model has solved the technical problem of high cost.

Description

Technical Field

[0001] This utility model belongs to the field of circuit technology, specifically, it relates to a bus communication circuit and electronic product. Background Technology

[0002] As energy efficiency requirements for home appliances continue to rise, traditional AC motors are being gradually upgraded to brushless DC motors to reduce energy consumption. This necessitates the addition of a frequency converter for the DC motor. Communication between multiple controllers utilizes bus communication circuits. Traditional bus communication circuits can only support one MCU communication unit. However, the high integration of current controllers means that a single controller may contain multiple MCUs, which may be powered by different power supplies such as 5V or 3.3V, and therefore have different requirements for the high and low levels of communication signals.

[0003] In a home appliance control system, there are typically multiple controllers that need to communicate with each other. However, due to increasing integration, some controllers now operate with two separate MCUs. The traditional solution is to use two separate communication circuits to communicate with each of the two MCUs.

[0004] The disadvantages of this approach are that having two sets of communication circuits increases costs, increases controller size, and wastes resources. Summary of the Invention

[0005] This invention provides a bus communication circuit that solves the technical problem of high cost in the prior art.

[0006] To achieve the above-mentioned technical objectives, the present invention adopts the following technical solution:

[0007] Bus communication circuit, including:

[0008] A first optocoupler has its input terminal at the light-emitting end connected to a power supply, its output terminal at the light-emitting end connected to a bus port, its input terminal at the light-receiving end connected to a first DC power supply, and its output terminal at the light-receiving end connected to the control terminal of a first switching transistor. One end of the switching path of the first switching transistor is connected to the cathode of a first diode. The anode of the first diode is connected to the receiving terminal of a first control unit and is connected to the first DC power supply through a first pull-up resistor. One end of the switching path of the first switching transistor is connected to the receiving terminal of a second control unit and is connected to a second DC power supply through a second pull-up resistor. The other end of the switching path of the first switching transistor is grounded. The voltage of the first DC power supply is less than the voltage of the second DC power supply.

[0009] The second optocoupler has its light-emitting input terminal connected to a first DC power supply via the switching path of a second switching transistor. The control terminal of the second switching transistor is connected to the anode of a second diode, and the cathode of the second diode is connected to the transmitting terminal of a first control unit. The control terminal of the second switching transistor is connected to the anode of a third diode, and the cathode of the third diode is connected to the transmitting terminal of the second control unit. The output terminal of the light-emitting end of the second optocoupler is grounded. The input terminal of the light-receiving end of the second optocoupler is connected to the power supply. The output terminal of the light-receiving end of the second optocoupler is connected to the control terminal of a third switching transistor. One end of the switching path of the third switching transistor is connected to the bus port and connected to the power supply via a third pull-up resistor. The other end of the switching path of the third switching transistor is grounded.

[0010] In some embodiments of this application, the control terminal of the second switch is connected to the first DC power supply via a fourth pull-up resistor.

[0011] In some embodiments of this application, the receiving end of the first control unit is grounded through a first filter capacitor;

[0012] The receiving end of the second control unit is grounded through the second filter capacitor.

[0013] In some embodiments of this application, a third filter capacitor is connected in parallel between the input and output terminals of the first optocoupler's light-emitting end.

[0014] In some embodiments of this application, the bus port is connected to the cathode of the TVS diode, and the anode of the TVS diode is grounded.

[0015] In some embodiments of this application, the bus port is connected to the anode of the fourth diode, and the cathode of the fourth diode is connected to the power supply.

[0016] In some embodiments of this application, the bus port is connected to the cathode of a fifth diode, and the anode of the fifth diode is grounded.

[0017] In some embodiments of this application, the first and third switching transistors are high on-state voltage drop transistors; the second switching transistor is a low on-state voltage drop transistor.

[0018] In some embodiments of this application, the first diode, the second diode, and the third diode are independent diodes, or are body diodes inside a MOSFET.

[0019] Based on the design of the bus communication circuit described above, this utility model proposes an electronic product, including the aforementioned bus communication circuit.

[0020] Compared with the prior art, the advantages and positive effects of this utility model are as follows: The bus communication circuit and electronic product of this utility model are designed such that the input terminal of the light-emitting end of the first optocoupler is connected to the power supply, the output terminal of the light-emitting end is connected to the bus port, the input terminal of the light-receiving end is connected to the first DC power supply, and the output terminal of the light-receiving end is connected to the control terminal of the first switching transistor; one end of the switching path of the first switching transistor is connected to the cathode of the first diode, the anode of the first diode is connected to the receiving terminal of the first control unit, and the anode of the first diode is connected to the first DC power supply through a first pull-up resistor; one end of the switching path of the first switching transistor is connected to the receiving terminal of the second control unit and is connected to the second DC power supply through a second pull-up resistor; the other end of the switching path of the first switching transistor is grounded; the voltage of the first DC power supply is less than the voltage of the second DC power supply. The input terminal of the light-emitting end of the second optocoupler is connected to the first DC power supply through the switching path of the second switching transistor, the control terminal of the second switching transistor is connected to the anode of the second diode, and the cathode of the second diode is connected to the transmitting terminal of the first control unit; the control terminal of the second switching transistor is connected to the anode of the third diode, and the cathode of the third diode is connected to the transmitting terminal of the second control unit; the output terminal of the light-emitting end of the second optocoupler is grounded. The input terminal of the light-receiving end of the second optocoupler is connected to the power supply; the output terminal of the light-receiving end of the second optocoupler is connected to the control terminal of the third switching transistor. One end of the switching path of the third switching transistor is connected to the bus port, and the other end of the switching path of the third switching transistor is grounded. One end of the switching path of the third switching transistor is connected to the power supply through a third pull-up resistor. This utility model's bus communication circuit and electronic product enables communication between control units powered by two different voltages, reducing costs and solving the problem of high cost in existing technologies.

[0021] Other features and advantages of this utility model will become clearer after reading the detailed description of the embodiments of this utility model in conjunction with the accompanying drawings. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of this utility model 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 some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a circuit schematic diagram of one embodiment of the bus communication circuit proposed in this utility model;

[0024] Figure 2 This is a circuit diagram of another embodiment of the bus communication circuit proposed in this utility model. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments.

[0026] It should be noted that in the description of this utility model, the terms "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," which indicate directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. These are used merely for ease of description and do not indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0027] Furthermore, it should be noted that, in the description of this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0028] Example 1

[0029] The bus communication circuit in this embodiment includes a first optocoupler U7, a second optocoupler U8, a first switch Q3, a second switch P3, a third switch Q4, etc., see [link to documentation]. Figure 1 As shown.

[0030] The first optocoupler U7 has its light-emitting end input terminal connected to a power supply (such as a 12V power supply), its light-emitting end output terminal connected to a bus port BUS, its light-receiving end input terminal connected to a first DC power supply (such as a 3.3V DC power supply), and its light-receiving end output terminal connected to the control terminal of the first switching transistor Q3.

[0031] One end of the switching path of the first switching transistor Q3 is connected to the cathode of the first diode D8; the anode of the first diode D8 is connected to the receiving terminal RXD1 of the first control unit (MCU1), and the anode of the first diode D8 is connected to the first DC power supply through the first pull-up resistor R87.

[0032] One end of the switching path of the first switching transistor Q3 is connected to the receiving terminal RXD2 of the second control unit (MCU2), and is connected to the second DC power supply (such as a 5V DC power supply) through the second pull-up resistor R92; the other end of the switching path of the first switching transistor Q3 is grounded. The voltage of the first DC power supply is less than the voltage of the second DC power supply.

[0033] The second optocoupler U8 has its light-emitting input terminal connected to the first DC power supply through the switching path of the second switch P3. The control terminal of the second switch P3 is connected to the anode of the second diode D20, and the cathode of the second diode D20 is connected to the transmitting terminal TXD1 of the first control unit (MCU1). The control terminal of the second switch P3 is connected to the anode of the third diode D22, and the cathode of the third diode D22 is connected to the transmitting terminal TXD2 of the second control unit (MCU2). The output terminal of the light-emitting end of the second optocoupler U8 is grounded.

[0034] The input terminal of the light-receiving end of the second optocoupler U8 is connected to the power supply; the output terminal of the light-receiving end of the second optocoupler U8 is connected to the control terminal of the third switch Q4; one end of the switching path of the third switch Q4 is connected to the bus port BUS; one end of the switching path of the third switch Q4 is connected to the power supply through the third pull-up resistor R104; and the other end of the switching path of the third switch Q4 is grounded.

[0035] The bus port (BUS) is used to connect to the communication bus to receive and send communication data, enabling communication with other devices. The bus port (BUS) receives signals transmitted on the bus and sends signals from the first control unit and the second control unit back to the bus.

[0036] When receiving a signal, the bus port BUS is at a low level, pulling the output of the first optocoupler U7 low. The current supplied by the power supply flows through the light-emitting end of the first optocoupler U7, turning on the light-emitting end of the first optocoupler U7 and turning on the light-receiving end of the first optocoupler U7. The current supplied by the first DC power supply flows through the light-receiving end of the first optocoupler U7, and the first DC power supply pulls the control end of the first switch Q3 high. The first switch Q3 turns on, pulling the receiving end RXD1 of the first control unit (MCU1) and the receiving end RXD2 of the second control unit (MCU2) low. The first control unit (MCU1) and the second control unit (MCU2) receive the signal.

[0037] When sending a signal, the transmitting terminals TXD1 of the first control unit (MCU1) and TXD2 of the second control unit (MCU2) are at low level, the control terminal of the second switch P3 is pulled low, the second switch P3 is turned on, the current provided by the first DC power supply flows through the second switch P3 and through the light-emitting terminal of the second optocoupler U8, the light-emitting terminal of the second optocoupler U8 is turned on, the current provided by the power supply flows through the light-receiving terminal of the second optocoupler U8, the power supply pulls the control terminal of the third switch Q4 to high level, the third switch Q4 is turned on, and the bus port BUS is pulled low to send the signal.

[0038] By designing the first optocoupler U7 and the second optocoupler U8, the bus port BUS is isolated from the first control unit and the second control unit. By designing the first diode D8, reverse current from the second DC power supply to the first DC power supply is prevented. By designing the second diode D20 and the third diode D22, signal interference is prevented when the transmitting terminals TXD1 of the first control unit and TXD2 of the second control unit are pulled low.

[0039] In this embodiment of the bus communication circuit, the input terminal of the light-emitting end of the first optocoupler U7 is connected to the power supply, the output terminal of the light-emitting end is connected to the bus port BUS, the input terminal of the light-receiving end is connected to the first DC power supply, and the output terminal of the light-receiving end is connected to the control terminal of the first switching transistor Q3. One end of the switching path of the first switching transistor Q3 is connected to the cathode of the first diode D8, the anode of the first diode D8 is connected to the receiving terminal RXD1 of the first control unit, and the anode of the first diode D8 is connected to the first DC power supply through the first pull-up resistor R87. One end of the switching path of the first switching transistor Q3 is connected to the receiving terminal RXD2 of the second control unit and is connected to the second DC power supply through the second pull-up resistor R92. The other end of the switching path of the first switching transistor Q3 is grounded. The voltage of the first DC power supply is less than the voltage of the second DC power supply. The input terminal of the light-emitting end of the second optocoupler U8 is connected to the first DC power supply through the switching path of the second switch P3. The control terminal of the second switch P3 is connected to the anode of the second diode D20, and the cathode of the second diode D20 is connected to the transmitting terminal TXD1 of the first control unit. The control terminal of the second switch P3 is connected to the anode of the third diode D22, and the cathode of the third diode D22 is connected to the transmitting terminal TXD2 of the second control unit. The output terminal of the light-emitting end of the second optocoupler U8 is grounded. The input terminal of the light-receiving end of the second optocoupler U8 is connected to the power supply. The output terminal of the light-receiving end of the second optocoupler U8 is connected to the control terminal of the third switch Q4. One end of the switching path of the third switch Q4 is connected to the bus port, and the other end of the switching path of the third switch Q4 is grounded. One end of the switching path of the third switch Q4 is connected to the power supply through the third pull-up resistor R104. The bus communication circuit of this embodiment enables communication between two control units powered by different voltages, reduces costs, and solves the problem of high cost in the prior art.

[0040] The bus communication circuit in this embodiment can be compatible with communication between two MCUs with different power supply voltages, saving costs, improving integration, and avoiding resource waste.

[0041] The bus communication circuit in this embodiment can support communication between two MCUs powered by different voltage levels on a single controller. A single communication circuit enables communication compatibility between two MCUs with different voltages, saving costs, improving controller integration, and avoiding wasted bus resources.

[0042] In some embodiments of this application, in order to ensure the stability of the state of the second switch P3, the control terminal of the second switch P3 is connected to the first DC power supply through the fourth pull-up resistor R113.

[0043] When no signal is needed, the first DC power supply makes the control terminal of the second switch P3 high, which turns off the second switch P3 and in turn turns off the second optocoupler U8.

[0044] When a signal needs to be sent, the transmitting end TXD1 of the first control unit and the transmitting end TXD2 of the second control unit send a low level, which pulls the control end of the second switch P3 to a low level, so that the second switch P3 is turned on, and thus the second optocoupler U8 is turned on.

[0045] In some embodiments of this application, the receiver RXD1 of the first control unit (MCU1) is grounded through the first filter capacitor C56 to filter out noise and prevent the receiver RXD1 from being interfered with by noise.

[0046] In some embodiments of this application, the receiver RXD2 of the second control unit (MCU2) is grounded through the second filter capacitor C81 to filter out noise and prevent the receiver RXD2 from being interfered with by noise.

[0047] In some embodiments of this application, a third filter capacitor C83 is connected in parallel between the input and output terminals of the light-emitting end of the first optocoupler U7 to filter out noise and prevent the light-emitting end of the first optocoupler U7 from being interfered with by noise.

[0048] In some embodiments of this application, to ensure circuit safety, the bus port BUS is connected to the cathode of the TVS diode, and the anode of the TVS diode is grounded.

[0049] TVS diodes provide rapid overvoltage protection for the circuit, protecting the bus port (BUS) from surge pulse damage and improving the overall circuit safety.

[0050] In some embodiments of this application, the bus port BUS is connected to the anode of the fourth diode, and the cathode of the fourth diode is connected to the power supply to prevent the current from the power supply from flowing to the bus port BUS.

[0051] In some embodiments of this application, the bus port BUS is connected to the cathode of a fifth diode, and the anode of the fifth diode is grounded to prevent the current of the bus port BUS from flowing to ground.

[0052] In some embodiments of this application, in order to facilitate the control of the switching transistors, the first switching transistor Q3 and the third switching transistor Q4 are high on-state voltage drop transistors; the second switching transistor P3 is a low on-state voltage drop transistor.

[0053] For example, the first switch Q3 and the third switch Q4 are NPN transistors, and the second switch P3 is a PNP transistor.

[0054] In some embodiments of this application, the first diode D8, the second diode D20, and the third diode D22 are independent diodes, which is simple, convenient, and low-cost. See [link / reference needed] Figure 1 As shown.

[0055] In some embodiments of this application, the first diode D8, the second diode D20, and the third diode D22 are body diodes inside the MOSFET, which is flexible and convenient to use. See [link to relevant documentation]. Figure 2 As shown.

[0056] The integrated diode within a MOSFET can provide the same isolation as a separate diode. Therefore, a separate diode can be replaced with a MOSFET, and the internal body diode of the MOSFET can also be used to isolate the communication between the two control units.

[0057] The bus communication circuit in this embodiment may include an isolated bus communication section, a non-isolated serial port communication section, and a two-MCU receiving and transmitting compatible section.

[0058] The first optocoupler U7, the second optocoupler U8, and the third switch Q4 form the isolated bus communication section;

[0059] The first switch Q3 and the second switch P3 together form the non-isolated serial communication section.

[0060] The first diode D8, the second diode D20, and the third diode D22 form the receiving and transmitting compatible parts of the two control units (MCUs).

[0061] Terminal block CN6 includes a bus port (port 3), a power port (port 2), and a ground port (port 1). The bus port (BUS) is used to connect to the BUS bus, the power port is used to provide power (12V ISO), and the ground port is used to connect to the ground wire.

[0062] The control logic is as follows:

[0063] (1) Isolation bus communication section: The two sides of the communication are isolated by two optocouplers. The bus section receives and sends communication data from the BUS port. The 12V power supply and GND provide power for communication.

[0064] When receiving a signal, the bus goes low, the bus port BUS is pulled low, and the current provided by the 12V power supply flows through the first optocoupler U7, turning on the first optocoupler U7, and the signal is transmitted from the isolated optocoupler to the non-isolated side.

[0065] When a signal is sent, the second optocoupler U8 is turned on, and the 12V power supply turns on the third switch Q4 through the second optocoupler U8, pulling the bus port BUS low and sending the signal.

[0066] (2) Non-isolated serial communication section:

[0067] When receiving a signal, the first optocoupler U7 is turned on, which causes the first switch Q3 to turn on, and the receiving terminals RXD1 and RXD2 are pulled low, so MCU1 and MCU2 receive the signal.

[0068] When transmitting a signal, the transmitting terminals TXD1 and TXD2 are pulled low, which turns on the second switch P3. The current provided by the first DC power supply of 3.3V passes through the second optocoupler U8, and U8 turns on.

[0069] (3) Compatibility between the two chips:

[0070] The receiving port RXD2 is the receiving port of MCU2 (the second control unit) powered by 5V, and RXD1 is the receiving port of MCU1 (the first control unit) powered by 3.3V. To prevent the 5V communication signal from entering the 3.3V powered MCU1, diode D8 is used to isolate the communication. The 5V powered MCU2 is pulled low to ground through the first switch Q3, and the 3.3V powered MCU1 is pulled low to ground through diode D8 and the first switch Q3.

[0071] The transmitting ends TXD1 and TXD2 use two diodes, D20 and D22, to isolate the transmitted signals pulled low, so that they do not interfere with each other.

[0072] Example 2

[0073] Based on the bus communication circuit in Embodiment 1, Embodiment 2 proposes an electronic product including the aforementioned bus communication circuit.

[0074] The electronic product in this embodiment, through the design of a bus communication circuit, can be compatible with the communication of two control units powered by different levels, reducing costs, solving the technical problem of high cost in the prior art, and improving the competitiveness of electronic products.

[0075] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this utility model.

Claims

1. A bus communication circuit, characterized in that: include: A first optocoupler has its input terminal at the light-emitting end connected to a power supply, its output terminal at the light-emitting end connected to a bus port, its input terminal at the light-receiving end connected to a first DC power supply, and its output terminal at the light-receiving end connected to the control terminal of a first switching transistor. One end of the switching path of the first switching transistor is connected to the cathode of a first diode. The anode of the first diode is connected to the receiving terminal of a first control unit and is connected to the first DC power supply through a first pull-up resistor. One end of the switching path of the first switching transistor is connected to the receiving terminal of a second control unit and is connected to a second DC power supply through a second pull-up resistor. The other end of the switching path of the first switching transistor is grounded. The voltage of the first DC power supply is less than the voltage of the second DC power supply. The second optocoupler has its light-emitting input terminal connected to a first DC power supply via the switching path of a second switching transistor. The control terminal of the second switching transistor is connected to the anode of a second diode, and the cathode of the second diode is connected to the transmitting terminal of a first control unit. The control terminal of the second switching transistor is connected to the anode of a third diode, and the cathode of the third diode is connected to the transmitting terminal of the second control unit. The output terminal of the light-emitting end of the second optocoupler is grounded. The input terminal of the light-receiving end of the second optocoupler is connected to the power supply. The output terminal of the light-receiving end of the second optocoupler is connected to the control terminal of a third switching transistor. One end of the switching path of the third switching transistor is connected to the bus port and connected to the power supply via a third pull-up resistor. The other end of the switching path of the third switching transistor is grounded.

2. The bus communication circuit according to claim 1, characterized in that: The control terminal of the second switch is connected to the first DC power supply through the fourth pull-up resistor.

3. The bus communication circuit according to claim 1, characterized in that: The receiving end of the first control unit is grounded through the first filter capacitor; The receiving end of the second control unit is grounded through the second filter capacitor.

4. The bus communication circuit according to claim 1, characterized in that: A third filter capacitor is connected in parallel between the input and output terminals of the first optocoupler's light-emitting end.

5. The bus communication circuit according to claim 1, characterized in that: The bus port is connected to the cathode of the TVS diode, and the anode of the TVS diode is grounded.

6. The bus communication circuit according to claim 1, characterized in that: The bus port is connected to the anode of the fourth diode, and the cathode of the fourth diode is connected to the power supply.

7. The bus communication circuit according to claim 1, characterized in that: The bus port is connected to the cathode of the fifth diode, and the anode of the fifth diode is grounded.

8. The bus communication circuit according to claim 1, characterized in that: The first and third switching transistors are high on-state voltage drop transistors; the second switching transistor is a low on-state voltage drop transistor.

9. The bus communication circuit according to any one of claims 1 to 8, characterized in that: The first diode, the second diode, and the third diode are independent diodes, or they are body diodes inside a MOSFET.

10. An electronic product, characterized in that: Includes the bus communication circuit as described in any one of claims 1 to 9.

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