Comparator-based RS-485 bus automatic transmit-receive control low power consumption circuit

Abstract

The utility model discloses an RS-485 bus automatic transmit-receive control low power consumption circuit based on a comparator. The RS-485 bus automatic transmit-receive control low power consumption circuit comprises an RS-485 transceiver U1, a comparator U2, a phase inverter U3 and an MOS tube Q1. The A port of the RS-485 transceiver U1 is connected with the IN + port of the comparator U2, and the B port of the RS-485 transceiver U1 is connected with the IN-port of the comparator U2; the VCC end of the RS-485 is connected with the source electrode of the MOS tube Q1, the drain electrode of the MOS tube Q1 is connected with the power supply, and the grid electrode of the MOS tube Q1 is connected with the OUT port of the comparator U2; an OUT port of the comparator U2 is respectively connected with an A end of the phase inverter U3 and a DE port of the RS-485 transceiver U1, a VDD end of the comparator U2 is connected with a power supply, and a VSS port of the comparator U2 is grounded; the Y end of the phase inverter U3 is connected with the RE port of the RS-485 transceiver U1, and the VCC end of the comparator U3 is connected with a power supply. Through the mutual cooperation of the RS-485 transceiver U1, the comparator U2, the phase inverter U3 and the MOS tube Q1, the automatic switching of the receiving and transmitting modes of the RS-485 transceiver U1 is realized, the MCU resource is not occupied, the response speed is effectively improved, and the power consumption is reduced.

Description

Technical Field

[0001] This utility model relates to the field of RS-485 bus technology, specifically to a comparator-based RS-485 bus automatic transmit / receive control low-power circuit. Background Technology

[0002] RS-485 communication is a commonly used communication protocol in industrial control environments. Its main function is to allow data communication between different devices. Because RS-485 communication has strong anti-interference capabilities and can stably transmit data over long distances, the RS-485 communication protocol is widely used in industrial automation systems.

[0003] The existing method of connecting the device to the RS-485 bus is to directly control the DE (transmit enable) and RE (receive enable) pins of the RS-485 transceiver through the GPIO pins of the microcontroller (MCU), and switch the transmit and receive modes according to software logic. However, this switching method consumes MCU resources, has high software complexity, limited response speed, and high power consumption. Utility Model Content

[0004] To address the shortcomings of existing technologies, a low-power circuit based on a comparator for automatic transmit and receive control of RS-485 bus is provided.

[0005] To achieve the above objectives, this utility model provides a low-power RS-485 bus automatic transmit / receive control circuit based on a comparator, including an RS-485 transceiver U1, a comparator U2, an inverter U3, and a MOSFET Q1. The RS-485 transceiver U1 has DI, DE, RE, RO, A, B, GND, and VCC ports; the comparator U2 has IN+, IN-, VSS, OUT, and VDD ports; and the inverter U3 has VCC, A, Y, and GND terminals. The A port of the RS-485 transceiver U1 and the IN port of the comparator U2... The + port is connected, the B port of RS-485 transceiver U1 is connected to the IN- port of comparator U2; the VCC terminal of RS-485 is connected to the source of MOSFET Q1, the drain of MOSFET Q1 is connected to the power supply, and the gate of MOSFET Q1 is connected to the OUT port of comparator U2; the OUT port of comparator U2 is connected to the A terminal of inverter U3 and the DE port of RS-485 transceiver U1 respectively, the VDD terminal of comparator U2 is connected to the power supply, and the VSS port of comparator U2 is grounded; the Y terminal of inverter U3 is connected to the RE port of RS-485 transceiver U1, and the VCC terminal of comparator U3 is connected to the power supply.

[0006] According to one embodiment of the present invention, a voltage regulator module is also included, which is connected in parallel between port A and port B of the RS-485 transceiver U1.

[0007] According to one embodiment of the present invention, the voltage regulator module includes a Zener diode ZD1, a Zener diode ZD2, and a Zener diode ZD3. The cathode of Zener diode ZD1 is connected to port B of RS-485 transceiver U1, and its anode is connected to port A of RS-485 transceiver U1. The cathode of Zener diode ZD2 is connected in series with the anode of Zener diode ZD1, and its other end is grounded. The anode of Zener diode ZD3 is connected to the anode of Zener diode ZD2 and ground, and its other end is connected to the cathode of Zener diode ZD1 and port B of RS-485 transceiver U1.

[0008] According to one embodiment of the present invention, a splitter unit is also included, one end of which is connected to port A of RS-485 transceiver U1, and the other end of which is connected to port B of RS-485 transceiver U1.

[0009] According to one embodiment of the present invention, it further includes a first anti-interference unit and a second anti-interference unit. One end of the first anti-interference unit is connected to port A of the RS-485 transceiver U1, and the other end is grounded. One end of the second anti-interference unit is connected to port B of the RS-485 transceiver U1, and the other end is grounded.

[0010] According to one embodiment of the present invention, it further includes an interface module, which includes a connector CON1, a resistor R4 and a resistor R5. The connector CON1 has a first pin and a second pin. One end of the resistor R4 is connected to port A of the RS-485 transceiver U1, and the other end is connected to the first pin of the connector CON1. ​​One end of the resistor R5 is connected to port B of the RS-485 transceiver U1, and the other end is connected to the second pin of the connector CON1.

[0011] According to one embodiment of the present invention, it further includes a discharge unit, one end of which is connected to the source of MOS transistor Q1, and the other end of which is connected to the drain of MOS transistor Q1.

[0012] The beneficial effect of this invention is that when the MCU sends data to the RS-485 transceiver U1, the A and B ports of the RS-485 transceiver U1 output differential data, creating a voltage difference between the two ports. Comparator U2 outputs a high level, turning on the MOSFET Q1. Simultaneously, inverter U3 inverts the high level, making the RE port of the RS-485 transceiver U1 high. At this time, the DE port of the RE-485 transceiver is low, and the RE port is high, causing the RS-485 transceiver U1 to switch to transmit mode. When the MCU does not send data to the RS-485 transceiver U1, there is no data output from ports A and B, resulting in no voltage difference between the two ports. Comparator U2 outputs a low level, turning off the MOSFET Q1. Furthermore, with the DE port of RS-485 transceiver U1 at a low level and the RE port at a high level, RS-485 transceiver U1 switches to receive mode. Through the cooperation of RS-485 transceiver U1, comparator U2, inverter U3, and MOSFET Q1, automatic switching of RS-485 transceiver U1's transmit and receive modes is achieved without occupying MCU resources, effectively improving response speed and reducing power consumption. Attached Figure Description

[0013] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments of this application and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0014] Figure 1 This is a circuit diagram of a comparator-based RS-485 bus automatic transmit / receive control low-power circuit in the embodiment.

[0015] Explanation of reference numerals in the attached figures

[0016] 1. Voltage regulator module; 2. Current shunt unit; 3. First anti-interference unit; 4. Second anti-interference unit; 5. Interface module; 6. Discharge unit. Detailed Implementation

[0017] The following drawings will disclose several embodiments of this utility model. For clarity, many practical details will be described in the following description. However, it should be understood that these practical details should not be used to limit this utility model. That is, in some embodiments of this utility model, these practical details are not essential. In addition, for the sake of simplicity, some conventional structures and components will be shown in the drawings in a simple schematic manner.

[0018] Furthermore, in this utility model, the use of terms such as "first" and "second" is for descriptive purposes only and does not specifically refer to any order or sequence, nor is it intended to limit the utility model. They are merely used to distinguish components or operations described with the same technical terms and should not be construed as indicating or implying their relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of various embodiments can be combined with each other, but only if they are feasible for those skilled in the art. If a combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this utility model.

[0019] Please refer to Figure 1 , Figure 1 This is a low-power circuit diagram for automatic transmit / receive control of an RS-485 bus based on a comparator. This embodiment provides a low-power circuit for automatic transmit / receive control of an RS-485 bus based on a comparator, which includes an RS-485 transceiver U1, a comparator U2, an inverter U3, and a MOSFET Q1. The RS-485 transceiver U1 has ports DI, DE, RE, RO, A, B, GND, and VCC. The comparator U2 has ports IN+, IN-, VSS, OUT, and VDD. The inverter U3 has terminals VCC, A, Y, and GND.

[0020] During connection, the DI and RO ports of RS-485 transceiver U1 are connected to the external MCU to receive data sent by the MCU. The A port of RS-485 transceiver U1 is connected to the IN+ port of comparator U2, and the B port of RS-485 transceiver U1 is connected to the IN- port of comparator U2. The VCC terminal of RS-485 is connected to the source of MOSFET Q1, the drain of MOSFET Q1 is connected to the power supply, and the gate of MOSFET Q1 is connected to the OUT port of comparator U2. The OUT port of comparator U2 is also connected to the A terminal of inverter U3 and the DE port of RS-485 transceiver U1. The VDD terminal of comparator U2 is connected to the power supply, and the VSS port of comparator U2 is grounded. The Y terminal of inverter U3 is connected to the RE port of RS-485 transceiver U1, and the VCC terminal of comparator U3 is connected to the power supply.

[0021] In practical applications, when an external MCU sends data to RS-485 transceiver U1, RS-485 transceiver U1 receives the data and converts it into a differential signal, outputting the differential signal from ports A and B. The IN+ port of comparator U2 is connected to port A of RS-485 transceiver U1, and the IN- port of comparator U2 is connected to port B of RS-485 transceiver U1. Comparator U2 is used to detect whether there is a voltage difference between the differential signals output from ports A and B of RS-485 transceiver U1.

[0022] If comparator U2 detects a voltage difference between port A and port B, its OUT port outputs a high level. At this time, the gate of MOSFET Q1 receives a high-level signal, and MOSFET Q1 conducts. The power supply then powers RS-485 transceiver U1 through MOSFET Q1, enabling RS-485 transceiver U1 to operate normally. Simultaneously, because comparator U2's OUT terminal outputs a high level, both RS-485 transceiver U1's DE port and inverter U3's A port are high. After inverter U3's A port goes high, it inverts the high-level signal output by comparator U2, causing inverter U3's Y terminal to output a low-level signal. RS-485 transceiver U1's RE port receives the low-level signal output from inverter U3's Y terminal. At this time, RS-485 transceiver U1's RE port is low, its DE port is high, and RS-485 transceiver U1 switches to transmit mode. In transmit mode, RS-485 transceiver U1 will output the received data from ports A and B of RS-485 transceiver U1.

[0023] When the external MCU stops sending data to RS-485 transceiver U1, comparator U2 detects that there is no voltage difference between ports A and B of RS-485 transceiver U1, and its OUT port outputs a low level. The gate of MOSFET Q1 receives a low-level signal, turning off Q1. The power supply cannot power RS-485 transceiver U1, and RS-485 transceiver U1 enters standby mode, thus avoiding power consumption and significantly reducing power consumption. At this time, ports DE of RS-485 transceiver U1 and port A of inverter U3 are both low. Inverter U3 inverts the received low-level signal, causing its Y terminal to output a high-level signal. At this time, port RE of RS-485 transceiver U1 is high, and port DE of RS-485 transceiver U1 is low, switching RS-485 transceiver U1 to receive mode.

[0024] Thus, comparator U2 determines whether there is a voltage difference between ports A and B of RS-485 transceiver U1, thereby determining whether the external MCU is sending data to RS-485 transceiver U1. When the MCU sends data to RS-485 transceiver U1, ports A and B of RS-485 transceiver U1 output differential data, creating a voltage difference between them. Comparator U2 outputs a high level, turning on MOSFET Q1. Simultaneously, inverter U3 inverts the high level, making port RE of RS-485 transceiver U1 high. At this time, ports DE of the RE-485 transceiver are low, and port RE is high, causing RS-485 transceiver U1 to switch to transmit mode. When the MCU does not send data to the RS-485 transceiver U1, there is no data output on ports A and B of the RS-485 transceiver U1, resulting in no voltage difference between ports A and B. Comparator U2 outputs a low level, turning off MOSFET Q1. Furthermore, ports DE of the RS-485 transceiver U1 are low, and port RE is high, switching the RS-485 transceiver U1 to receive mode. Through the cooperation of RS-485 transceiver U1, comparator U2, inverter U3, and MOSFET Q1, automatic switching between transmit and receive modes of the RS-485 transceiver U1 is achieved without consuming MCU resources, effectively improving response speed and reducing power consumption.

[0025] Furthermore, the comparator-based RS-485 bus automatic transmit / receive control low-power circuit also includes a voltage regulator module 1. The voltage regulator module 1 is connected in parallel between port A and port B of the RS-485 transceiver U1. The voltage regulator module 1 is used to regulate the differential signals output from ports A and B of the RS-485 transceiver U1.

[0026] Specifically, the voltage regulator module 1 includes three Zener diodes: ZD1, ZD2, and ZD3. The cathode of Zener diode ZD1 is connected to port B of RS-485 transceiver U1, and its anode is connected to port A of RS-485 transceiver U1. The cathode of Zener diode ZD2 is connected to both the anode of Zener diode ZD1 and port A of RS-485 transceiver U1, with its other end grounded. The cathode of Zener diode ZD3 is connected to port B of RS-485 transceiver U1, and its other end is connected to both the anode of Zener diode ZD2 and ground. Zener diodes ZD1, ZD2, and ZD3 are used to stabilize the voltage. The differential signals output from ports A and B of RS-485 transceiver U1 are regulated by Zener diodes ZD1, ZD2, and ZD3 before being output, thus reducing noise in the differential signals.

[0027] Furthermore, the comparator-based RS-485 bus automatic transmit / receive control low-power circuit also includes a current shunt unit 2. One end of the current shunt unit 2 is connected to port A of the RS-485 transceiver U1, and the other end is connected to port B of the RS-485 transceiver U1. The current shunt unit 2 is used for current limiting protection. When the output signal current of the RS-485 transceiver U1 is too large, the current shunt unit 2 is used to limit the current magnitude to prevent excessive current from damaging the components in the circuit. In this example, the current shunt unit 2 includes a resistor R1. One end of the resistor R1 is connected to port A of the RS-485 transceiver U1, and the other end is connected to port B of the RS-485 transceiver U1.

[0028] Furthermore, the comparator-based RS-485 bus automatic transmit / receive control low-power circuit also includes a first anti-interference unit 3 and a second anti-interference unit 4. One end of the first anti-interference unit 3 is connected to port A of the RS-485 transceiver U1, and the other end is grounded. One end of the second anti-interference unit 4 is connected to port B of the RS-485 transceiver U1, and the other end is grounded. The first anti-interference unit 3 and the second anti-interference unit 4 are used to reduce signal reflection and interference to ensure circuit stability.

[0029] In this example, the first anti-interference unit 3 includes a resistor R8, and the second anti-interference unit 4 includes a resistor R7. One end of the resistor R8 is connected to port A of the RS-485 transceiver U1, and the other end is grounded. One end of the resistor R7 is connected to port B of the RS-485 transceiver U1, and the other end is grounded.

[0030] The comparator-based RS-485 bus automatic transmit / receive control low-power circuit also includes a bleeder unit 6. One end of the bleeder unit 6 is connected to the source of the MOSFET Q1, and the other end is connected to the drain of the MOSFET Q1. The bleeder unit 6 is used to bleed the charge on the gate of the MOSFET Q1, accelerate the switching speed of the MOSFET Q1, and protect the MOSFET Q1 from damage.

[0031] The comparator-based RS-485 bus automatic transmit / receive control low-power circuit also includes a bleeder unit 6 and an interface module 5. Interface module 5 is used to connect the RS-485 transceiver U1 to an external receiver. Interface module 5 includes connector CON1, resistor R4, and resistor R5. Connector CON1 has a first pin and a second pin. One end of resistor R4 is connected to port A of RS-485 transceiver U1, and the other end is connected to the first pin of CON1. ​​One end of resistor R4 is connected to port B of RS-485 transceiver U1, and the other end is connected to the second pin of CON1. ​​Resistors R4 and R5 are used for current limiting. Connector CON1 is used for connection to an external receiver.

[0032] The above description is merely an embodiment of this utility model and is not intended to limit the scope of this utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of this utility model should be included within the scope of the claims of this utility model.

Claims

1. A comparator-based RS-485 bus automatic transmit / receive control low-power circuit, characterized in that, include: The system comprises an RS-485 transceiver U1, a comparator U2, an inverter U3, and a MOSFET Q1. The RS-485 transceiver U1 has ports DI, DE, RE, RO, A, B, GND, and VCC. The comparator U2 has ports IN+, IN-, VSS, OUT, and VDD. The inverter U3 has terminals VCC, A, Y, and GND. Port A of the RS-485 transceiver U1 is connected to the IN+ port of the comparator U2, and port B of the RS-485 transceiver U1 is connected to the comparator U3. The comparator U2 has an IN port; the VCC terminal of the RS-485 is connected to the source of MOSFET Q1, the drain of MOSFET Q1 is connected to the power supply, and the gate of MOSFET Q1 is connected to the OUT port of comparator U2; the OUT port of comparator U2 is connected to the A terminal of inverter U3 and the DE port of RS-485 transceiver U1, the VDD terminal of comparator U2 is connected to the power supply, and the VSS port of comparator U2 is grounded; the Y terminal of inverter U3 is connected to the RE port of RS-485 transceiver U1, and the VCC terminal of comparator U3 is connected to the power supply.

2. The comparator-based RS-485 bus automatic transmit / receive control low-power circuit according to claim 1, characterized in that, It also includes a voltage regulator module (1), which is connected in parallel between port A and port B of the RS-485 transceiver U1.

3. The comparator-based RS-485 bus automatic transmit / receive control low-power circuit according to claim 2, characterized in that, The voltage regulator module (1) includes a Zener diode ZD1, a Zener diode ZD2, and a Zener diode ZD3. The negative terminal of the Zener diode ZD1 is connected to port B of the RS-485 transceiver U1, and its positive terminal is connected to port A of the RS-485 transceiver U1. The negative terminal of the Zener diode ZD2 is connected in series with the positive terminal of the Zener diode ZD1, and its other end is grounded. The positive terminal of the Zener diode ZD3 is connected to the positive terminal of the Zener diode ZD2 and ground, and its other end is connected to the negative terminal of the Zener diode ZD1 and port B of the RS-485 transceiver U1.

4. The comparator-based RS-485 bus automatic transmit / receive control low-power circuit according to claim 1, characterized in that, It also includes a splitting unit (2), one end of which is connected to port A of the RS-485 transceiver U1, and the other end of which is connected to port B of the RS-485 transceiver U1.

5. The comparator-based RS-485 bus automatic transmit / receive control low-power circuit according to claim 1, characterized in that, It also includes a first anti-interference unit (3) and a second anti-interference unit (4). One end of the first anti-interference unit (3) is connected to port A of the RS-485 transceiver U1, and the other end is grounded. One end of the second anti-interference unit (4) is connected to port B of the RS-485 transceiver U1, and the other end is grounded.

6. The comparator-based RS-485 bus automatic transmit / receive control low-power circuit according to claim 1, characterized in that, It also includes an interface module (5), which includes a connector CON1, a resistor R4 and a resistor R5. The connector CON1 has a first pin and a second pin. One end of the resistor R4 is connected to the A port of the RS-485 transceiver U1, and the other end is connected to the first pin of the connector CON1. ​​One end of the resistor R5 is connected to the B port of the RS-485 transceiver U1, and the other end is connected to the second pin of the connector CON1.

7. The comparator-based RS-485 bus automatic transmit / receive control low-power circuit according to claim 1, characterized in that, It also includes a discharge unit (6), one end of which is connected to the source of the MOS transistor Q1, and the other end of which is connected to the drain of the MOS transistor Q1.

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