CN217741715U - Single-wire half-duplex UART circuit - Google Patents
Single-wire half-duplex UART circuit Download PDFInfo
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- CN217741715U CN217741715U CN202221043521.1U CN202221043521U CN217741715U CN 217741715 U CN217741715 U CN 217741715U CN 202221043521 U CN202221043521 U CN 202221043521U CN 217741715 U CN217741715 U CN 217741715U
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Abstract
The utility model relates to a single-wire half-duplex UART circuit, which comprises at least two connected communication nodes, wherein each communication node comprises a signal sending end and a signal receiving end; the method is characterized in that: each communication node is internally provided with an isolation circuit, two optocouplers respectively connected with a signal sending end and a signal receiving end of the corresponding communication node are arranged in each isolation circuit, and all optocouplers between any two communication nodes are connected in series, so that the electrical isolation between any two communication nodes is realized. The utility model has the advantages that: two optocouplers respectively connected with the signal sending end and the signal receiving end are arranged in each communication node, so that the optocouplers are used as signal isolation devices, and electrical isolation between the communication nodes is realized. Therefore, the two communication nodes have simple structures, and can meet the requirement of electrical isolation while realizing the single-wire half-duplex UART communication circuit.
Description
Technical Field
The utility model relates to a UART communication technology field, in particular to single line half-duplex UART circuit.
Background
UART (universal asynchronous receiver transmitter) communication is one of the most common forms of hardware communication. Most MCUs have 1 or more UART communication interfaces. The UART communication interface comprises 2 signal interfaces of TX (transmission) and RX (reception), is a full-duplex interface, can simultaneously realize data transmission and data reception, and the processes of the TX and the RX are independent from each other and do not interfere with each other. However, in some special cases, in order to save the number of signal lines, a single-wire half-duplex UART communication is used, and TX and RX operations need to be time-division multiplexed on 1 signal line.
An existing single-wire half-duplex circuit is shown in fig. 1, and the circuit includes a first node 1 and a second node 2 connected to each other, and if there is a potential difference between reference grounds of the first node 1 and the second node 2, a terminal 2 of each node that receives and transmits signals needs to be electrically isolated, but because the single-wire half-duplex circuit in fig. 1 cannot achieve electrical isolation, an isolation process needs to be performed on the interface circuit. Further improvements are needed for this purpose.
SUMMERY OF THE UTILITY MODEL
The utility model aims to solve the technical problem that a single line half-duplex UART circuit that can realize electrical isolation is provided to above-mentioned prior art.
The utility model provides a technical scheme that above-mentioned technical problem adopted does: a single-wire half-duplex UART circuit comprises at least two connected communication nodes, wherein each communication node comprises a signal sending end and a signal receiving end; the method is characterized in that: each communication node is internally provided with an isolation circuit, two optocouplers respectively connected with a signal sending end and a signal receiving end of the corresponding communication node are arranged in each isolation circuit, and all optocouplers between any two communication nodes are connected in series, so that the electrical isolation between any two communication nodes is realized.
In order to realize the conversion of high and low levels, the collector of the triode in each optocoupler is also connected with a pull-up resistor in series.
The anode of the light emitting diode in each optocoupler is also connected with a current limiting resistor in series.
In this scheme, the number of the communication nodes is two, and the two communication nodes are respectively a first communication node and a second communication node, the first communication node includes a first signal sending end and a first signal receiving end, and the second communication node includes a second signal sending end and a second signal receiving end.
Furthermore, the number of the isolation circuits is two, and the two isolation circuits are respectively a first isolation circuit arranged in the first communication node and a second isolation circuit arranged in the second communication node;
the first isolation circuit comprises a first optocoupler and a third optocoupler, wherein the cathode of a light emitting diode in the first optocoupler is connected with a first signal sending end, the collector electrode of a triode in the first optocoupler is connected with the cathode of the light emitting diode in the third optocoupler, and the collector electrode of the triode in the third optocoupler is connected with a first signal receiving end;
the second isolation circuit comprises a second optocoupler and a fourth optocoupler, wherein the cathode of a light emitting diode in the second optocoupler is connected with a second signal sending end, the collector electrode of a triode in the second optocoupler is connected with the cathode of the light emitting diode in the fourth optocoupler, and the fourth optocoupler (the collector electrode of the triode in the fourth optocoupler is connected with a second signal receiving end;
a triode collector in the first optocoupler, a light-emitting diode cathode in the third optocoupler, a triode collector in the second optocoupler and a light-emitting diode cathode in the fourth optocoupler are connected in series; and the emitting electrode of the triode in the first optocoupler, the emitting electrode of the triode in the third optocoupler, the emitting electrode of the triode in the second optocoupler and the emitting electrode of the triode in the fourth optocoupler are connected with respective grounding ends.
In order to realize independent power supply of the isolation side of each communication node, the current-limiting resistor connected in series with the anode of the light-emitting diode of the first optocoupler and the pull-up resistor connected in series with the collector of the triode in the third optocoupler are both connected with the first power supply.
Furthermore, a current-limiting resistor connected in series with the anode of the light-emitting diode in the second optocoupler and a pull-up resistor connected in series with the collector of the triode in the fourth optocoupler are both connected with a second power supply.
In order to realize the independent power supply at the single-wire connection part of the communication node, a pull-up resistor connected in series with a triode collector in the first optocoupler, a current-limiting resistor connected in series with the anode of a light-emitting diode in the third optocoupler and a current-limiting resistor connected in series with the anode of a light-emitting diode in the fourth optocoupler are all connected with a third power supply.
Preferably, the collector of the triode in the first optocoupler and the collector of the triode in the second optocoupler share the same pull-up resistor. Therefore, the situation that the signal lines are short-circuited can be avoided even if a plurality of sending ports send data at the same time.
Preferably, the emitter of the triode in the first optocoupler and the emitter of the triode in the second optocoupler are connected with the same ground terminal.
Compared with the prior art, the utility model has the advantages of: two optocouplers respectively connected with the signal sending end and the signal receiving end are arranged in each communication node, so that the optocouplers are used as signal isolation devices, and electrical isolation between the communication nodes is realized. Therefore, the two communication nodes have simple structures, and can meet the requirement of electrical isolation while realizing the single-wire half-duplex UART communication circuit.
Drawings
FIG. 1 is a circuit diagram of a single line half duplex UART circuit of the prior art;
fig. 2 is a circuit diagram of a single-wire half-duplex UART circuit (2 communication nodes communicating) according to an embodiment of the present invention;
fig. 3 is a circuit diagram of a single-wire half-duplex UART circuit according to an embodiment of the present invention (4 communication nodes communicating).
Detailed Description
The present invention will be described in further detail with reference to the following embodiments.
The single-wire half-duplex UART circuit in the embodiment comprises at least two communication nodes which are connected, each communication node comprises a signal sending end and a signal receiving end, an isolation circuit is further arranged in each communication node, two optical couplers which are respectively connected with the signal sending end and the signal receiving end of the corresponding communication node are arranged in each isolation circuit, and all the optical couplers between any two communication nodes are connected in series, so that the electrical isolation between any two communication nodes is realized.
In order to ensure that each optocoupler works normally, the anode of the light-emitting diode in each optocoupler is also connected with a current limiting resistor in series. In addition, a triode collector in each optocoupler is also connected with a pull-up resistor in series.
For facilitating understanding of the single-wire half-duplex UART circuit, in this embodiment, two communication nodes are provided, namely, a first communication node 3 and a second communication node 4, and the communication between the two connected communication nodes is taken as an example for description, where the first communication node 3 includes a first signal transmitting terminal TX1 and a first signal receiving terminal RX1, and the second communication node 4 includes a second signal transmitting terminal TX2 and a second signal receiving terminal RX2; correspondingly, the number of the isolation circuits is two, namely a first isolation circuit 5 arranged in the first communication node 3 and a second isolation circuit 6 arranged in the second communication node 4;
as shown in fig. 2, the first isolation circuit 5 includes a first optocoupler E1 and a third optocoupler E3, a cathode of a light emitting diode in the first optocoupler E1 is connected with a first signal sending terminal TX1, a collector of a triode in the first optocoupler E1 is connected with a cathode of a light emitting diode in the third optocoupler E3, and a collector of a triode in the third optocoupler E3 is connected with a first signal receiving terminal RX1; the second isolation circuit 6 comprises a second optocoupler E2 and a fourth optocoupler E4, the cathode of a light emitting diode in the second optocoupler E2 is connected with a second signal sending end TX2, the collector of a triode in the second optocoupler E2 is connected with the cathode of a light emitting diode in the fourth optocoupler E4, and the collector of a triode in the fourth optocoupler E4 is connected with a second signal receiving end RX2; a triode collector in the first optocoupler E1, a light emitting diode cathode in the third optocoupler E3, a triode collector in the second optocoupler E2 and a light emitting diode cathode in the fourth optocoupler E4 are connected in series; and the emitting electrode of the triode in the first optocoupler E1, the emitting electrode of the triode in the third optocoupler E3, the emitting electrode of the triode in the second optocoupler E2 and the emitting electrode of the triode in the fourth optocoupler E4 are connected with respective grounding ends.
A current limiting resistor (corresponding to a twelfth resistor R12) serially connected with the anode of the light emitting diode of the first optocoupler E1 and a pull-up resistor (corresponding to a fifteenth resistor R15) serially connected with the collector of a triode in the third optocoupler E3 are both connected with a first power supply VCC1; a current limiting resistor (corresponding to a fourteenth resistor R14) serially connected with the anode of the light emitting diode in the second optocoupler E2 and a pull-up resistor (corresponding to an eighteenth resistor R18) serially connected with the collector of the triode in the fourth optocoupler E4 are both connected with a second power supply VCC2; a pull-up resistor (corresponding to a thirteenth resistor R13) connected in series with a collector of a triode in the first optocoupler E1, a current-limiting resistor (corresponding to a sixteenth resistor R16) connected in series with an anode of a light-emitting diode in the third optocoupler E3, and a current-limiting resistor (corresponding to a seventeenth resistor R17) connected in series with an anode of a light-emitting diode in the fourth optocoupler E4 are connected with a third power supply VISO. In addition, a grounding end GND1 connected with an emitter of a triode in the third optocoupler E3 is a grounding wire of the first power supply VCC1, a grounding end GISO connected with an emitter of a triode in the first optocoupler E1 and an emitter of a triode in the second optocoupler E2 is a grounding wire of the third power supply VISO, and a grounding end GND2 connected with an emitter of a triode in the fourth optocoupler E4 is a grounding wire of the second power supply VCC2; the ground terminals GND1, GND2 and GISO have a potential difference.
The first power supply VCC1, the second power supply VCC2 and the third power supply VISO are all different power supplies, so that the isolated side of each communication node can be ensured to be independently powered; meanwhile, the connection of the communication nodes needs to be separately powered.
In addition, the collector of the triode in the first optocoupler E1 and the collector of the triode in the second optocoupler E2 share the same pull-up resistor, which corresponds to a thirteenth resistor R13 in FIG. 2, so that high-level output is realized through the pull-up resistor.
The working principle of a signal sending end in the single-wire half-duplex UART circuit in the embodiment is as follows:
when the TX1 sends 1, the first optocoupler E1 is cut off, and the output 1 is pulled up through a thirteenth resistor R13;
when the TX1 sends 0, the first optocoupler E1 is conducted to output a low level;
when the TX2 sends 1, the second optocoupler E2 is cut off, and the output 1 is pulled up through a thirteenth resistor R13;
when the TX2 sends 0, the second optocoupler E2 is conducted, and a low level is output;
the working principle of a signal receiving end in the single-wire half-duplex UART circuit is as follows:
when an external input 1 is input, the third optical coupler E3/the fourth optical coupler E4 are cut off, and the fifteenth resistor R15 pulls up to enable the RX1 to output 1/the eighteenth resistor R18 pulls up to enable the RX2 to output 1;
when 0 is input externally, the third optical coupler E3/the fourth optical coupler E4 are conducted, and RX1/RX2 outputs 0.
The above 1 and 0 correspond to high level and low level, respectively. Since the high level is pulled up by the thirteenth resistor R13, even if a plurality of transmission ports are transmitting data at the same time, the signal line is not short-circuited.
To illustrate that the single-wire half-duplex UART circuit can also realize the isolation of a plurality of communication nodes, as shown in fig. 3, the single-wire half-duplex UART circuit is a single-wire half-duplex UART circuit with 4 communication nodes, and is used for realizing the communication among the first communication node 3, the second communication node 4, the third communication node 5, and the fourth communication node 6, and the principle thereof can refer to the single-wire half-duplex UART circuit with 2 communication nodes shown in fig. 2. Of course, the number of the communication nodes in the single-wire half-duplex UART circuit is not limited to that shown in fig. 2 and 3 in this embodiment, and may be other numbers.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, a plurality of improvements and decorations can be made without departing from the technical principle of the present invention, and these improvements and decorations should also be regarded as the protection scope of the present invention.
Claims (10)
1. A single-wire half-duplex UART circuit comprises at least two connected communication nodes, wherein each communication node comprises a signal sending end and a signal receiving end; the method is characterized in that: each communication node is internally provided with an isolation circuit, two optocouplers respectively connected with a signal sending end and a signal receiving end of the corresponding communication node are arranged in each isolation circuit, and all optocouplers between any two communication nodes are connected in series, so that the electrical isolation between any two communication nodes is realized.
2. The single-wire half-duplex UART circuit of claim 1, wherein: and a triode collector in each optocoupler is also connected with a pull-up resistor in series.
3. The single-wire, half-duplex UART circuit of claim 2, wherein: the anode of the light emitting diode in each optocoupler is also connected with a current limiting resistor in series.
4. The single-wire half-duplex UART circuit according to any one of claims 1 to 3, characterized in that: the communication nodes are two and are respectively a first communication node (3) and a second communication node (4), the first communication node (3) comprises a first signal sending end (TX 1) and a first signal receiving end (RX 1), and the second communication node (4) comprises a second signal sending end (TX 2) and a second signal receiving end (RX 2).
5. The single-wire half-duplex UART circuit of claim 4, wherein: the number of the isolation circuits is two, and the two isolation circuits are respectively a first isolation circuit (5) arranged in the first communication node (3) and a second isolation circuit (6) arranged in the second communication node (4);
the first isolation circuit (5) comprises a first optocoupler (E1) and a third optocoupler (E3), the cathode of a light emitting diode in the first optocoupler (E1) is connected with a first signal sending end (TX 1), the collector of a triode in the first optocoupler (E1) is connected with the cathode of a light emitting diode in the third optocoupler (E3), and the collector of a triode in the third optocoupler (E3) is connected with a first signal receiving end (RX 1);
the second isolation circuit (6) comprises a second optocoupler (E2) and a fourth optocoupler (E4), the cathode of a light emitting diode in the second optocoupler (E2) is connected with a second signal sending end (TX 2), the collector of a triode in the second optocoupler (E2) is connected with the cathode of a light emitting diode in the fourth optocoupler (E4), and the collector of a triode in the fourth optocoupler (E4) is connected with a second signal receiving end (RX 2);
a triode collector electrode in the first optocoupler (E1), a light emitting diode cathode in the third optocoupler (E3), a triode collector electrode in the second optocoupler (E2) and a light emitting diode cathode in the fourth optocoupler (E4) are all connected in series; and the triode emitting electrode in the first optocoupler (E1), the triode emitting electrode in the third optocoupler (E3), the triode emitting electrode in the second optocoupler (E2) and the triode emitting electrode in the fourth optocoupler (E4) are connected with respective grounding ends.
6. The single-wire half-duplex UART circuit of claim 5, wherein: and the current-limiting resistor connected in series with the anode of the light-emitting diode of the first optocoupler (E1) and the pull-up resistor connected in series with the collector of the triode in the third optocoupler (E3) are both connected with a first power supply (VCC 1).
7. The single-wire half-duplex UART circuit of claim 6, wherein: and a current-limiting resistor connected with the anode of the light-emitting diode in the second optocoupler (E2) in series and a pull-up resistor connected with the collector of the triode in the fourth optocoupler (E4) in series are both connected with a second power supply (VCC 2).
8. The single-wire half-duplex UART circuit of claim 7, wherein: and a pull-up resistor connected in series with a triode collector in the first optocoupler (E1), a current-limiting resistor connected in series with a light-emitting diode anode in the third optocoupler (E3) and a current-limiting resistor connected in series with a light-emitting diode anode in the fourth optocoupler (E4) are connected with a third power supply (VISO).
9. The single-wire half-duplex UART circuit of claim 5, wherein: and the triode collector in the first optocoupler (E1) and the triode collector in the second optocoupler (E2) share the same pull-up resistor.
10. The single-wire half-duplex UART circuit of claim 9, wherein: and the emitting electrode of the triode in the first optocoupler (E1) and the emitting electrode of the triode in the second optocoupler (E2) are connected with the same grounding terminal (GISO).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202221043521.1U CN217741715U (en) | 2022-04-29 | 2022-04-29 | Single-wire half-duplex UART circuit |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202221043521.1U CN217741715U (en) | 2022-04-29 | 2022-04-29 | Single-wire half-duplex UART circuit |
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| Publication Number | Publication Date |
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| CN217741715U true CN217741715U (en) | 2022-11-04 |
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| CN202221043521.1U Active CN217741715U (en) | 2022-04-29 | 2022-04-29 | Single-wire half-duplex UART circuit |
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| CN (1) | CN217741715U (en) |
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