CN214474985U - Single-wire serial port communication circuit - Google Patents
Single-wire serial port communication circuit Download PDFInfo
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- CN214474985U CN214474985U CN202120716663.9U CN202120716663U CN214474985U CN 214474985 U CN214474985 U CN 214474985U CN 202120716663 U CN202120716663 U CN 202120716663U CN 214474985 U CN214474985 U CN 214474985U
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Abstract
The utility model discloses a single-wire serial port communication circuit, which comprises a first communication circuit and a second communication circuit; the signal end of the first communication circuit is connected with the first signal receiving end, and the first signal receiving end is connected with the signal end of the second communication circuit through a single wire; the input end of the first communication circuit is connected with the first signal sending end; the second communication circuit comprises a receiving circuit and a transmitting circuit, the receiving circuit is used for carrying out level conversion on signals from the first communication circuit, the transmitting circuit is used for carrying out level conversion on the signals transmitted to the first communication circuit, the signal end of the second communication circuit is respectively connected with the input end of the receiving circuit and the output end of the transmitting circuit, the output end of the receiving circuit is connected with the second signal receiving end, the input end of the transmitting circuit is connected with the second signal transmitting end, and single-wire serial port communication can be normally carried out on the two devices under different power supply voltages.
Description
Technical Field
The utility model relates to the field of communication technology, especially, relate to a single line serial ports communication circuit.
Background
A common UART serial port is generally a two-wire type, and includes a TX transmitting signal line and an RX receiving signal line, where a TX pin of the UART serial port is connected to the TX transmitting signal line, and an RX pin is connected to the RX receiving signal line. In the existing scheme, a method for performing single-wire communication between two devices is to convert a TX signal transmission line and an RX signal reception line of a UART into a single wire for communication. However, communication needs to be supported only when the two devices use the same power supply voltage value, for example, if the power supply voltage of the device 1 is 3.0V, the power supply voltage of the device 2 is required to be 3.0V, normal communication can be performed, and if the power supply voltage of the device 2 is 1.8V, communication abnormality is caused due to different level determination thresholds. Therefore, the two devices cannot normally communicate at different supply voltages.
Disclosure of Invention
The utility model provides a purpose provides a single line serial ports communication circuit realizes that two equipment can normally carry out single line serial ports communication under different supply voltage.
In order to achieve the above object, an embodiment of the present invention provides a single-wire serial port communication circuit, which includes a first communication circuit and a second communication circuit, wherein the single-wire serial port communication circuit has a first signal transmitting terminal, a second signal transmitting terminal, a first signal receiving terminal and a second signal receiving terminal;
the signal end of the first communication circuit is connected with the first signal receiving end, and the first signal receiving end is connected with the signal end of the second communication circuit through a single wire; the input end of the first communication circuit is connected with the first signal sending end;
the second communication circuit comprises a receiving circuit used for carrying out level conversion on signals from the first communication circuit and a sending circuit used for carrying out level conversion on signals sent to the first communication circuit, the signal end of the second communication circuit is respectively connected with the input end of the receiving circuit and the output end of the sending circuit, the output end of the receiving circuit is connected with the second signal receiving end, and the input end of the sending circuit is connected with the second signal sending end.
In some embodiments, the first communication circuit comprises a first transistor, a first resistor, a second resistor, and a third resistor;
the emitting electrode of the first triode is connected with the first signal sending end; the base electrode of the first triode is connected between the first resistor and the third resistor, the first resistor is connected with a first power supply, and the third resistor is grounded; and the collector of the first triode is respectively connected with one end of the second resistor and the first signal receiving end, and the other end of the second resistor is connected with the first power supply.
In some embodiments, the transmit circuit includes a second transistor, a fourth resistor, and a fifth resistor;
the emitting electrode of the second triode is connected with the second signal sending end, the base electrode of the second triode is connected with the second power supply through the fifth resistor, the collecting electrode of the second triode is connected with the second power supply through the fourth resistor, and the collecting electrode of the second triode is connected with the output end of the sending circuit.
In some embodiments, the receiving circuit comprises a third transistor, a sixth resistor and a seventh resistor;
an emitting electrode of the third triode is connected with an input end of the receiving circuit, a collector electrode of the third triode is connected with the second signal receiving end, a base electrode of the third triode is connected between the sixth resistor and the seventh resistor, the sixth resistor is grounded, and the seventh resistor is connected with a third power supply.
In some embodiments, the second communication circuit further comprises a clamping circuit;
the clamping circuit is connected to the base electrode of the second triode.
In some embodiments, the clamping circuit comprises a clamping diode;
the positive electrode of the clamping diode is connected with the base electrode of the second triode, and the negative electrode of the clamping diode is connected with a fourth power supply.
In some embodiments, the clamping circuit comprises a voltage regulator tube and a current limiting resistor;
the anode of the voltage regulator tube is grounded, the base electrode of the second triode is connected between the cathode of the voltage regulator tube and the first end of the current-limiting resistor, and the second end of the current-limiting resistor is connected with the second power supply.
In some embodiments, the first transistor, the second transistor, and the third transistor are all NPN transistors.
Compared with the prior art, the utility model discloses a single-wire serial port communication circuit, single-wire serial port communication circuit includes first communication circuit and second communication circuit, single-wire serial port communication circuit has first signal transmitting terminal, second signal transmitting terminal, first signal receiving terminal and second signal receiving terminal, the signal end of first communication circuit with first signal receiving terminal is connected, first signal receiving terminal through single-wire with the signal end of second communication circuit is connected; the input end of the first communication circuit is connected with the first signal sending end, the second communication circuit comprises a receiving circuit used for carrying out level conversion on signals from the first communication circuit and a sending circuit used for carrying out level conversion on signals sent to the first communication circuit, the signal end of the second communication circuit is respectively connected with the input end of the receiving circuit and the output end of the sending circuit, the output end of the receiving circuit is connected with the second signal receiving end, and the input end of the sending circuit is connected with the second signal sending end. By arranging the transmitting circuit and the receiving circuit with the level conversion function, the first communication circuit is controlled to transmit signals to the second communication circuit under the condition that the power supply voltages of the two communication circuits are different, the second communication circuit is controlled to transmit signals to the first communication circuit, the transmission and the reception are realized, and the single-wire serial communication can be normally carried out. And simultaneously, the utility model discloses a circuit structure is simplified to the structure, has reduced the hardware cost to be applicable to multiple different supply voltage's the condition, have the wide characteristics of application scope.
Drawings
Fig. 1 is the embodiment of the present invention, which is a schematic structural diagram of a single-wire serial communication circuit.
Detailed Description
The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative efforts belong to the protection scope of the present invention.
Referring to fig. 1, which is a schematic structural diagram of a single-wire serial communication circuit in an embodiment of the present invention, the single-wire serial communication circuit includes a first communication circuit 1 and a second communication circuit 2, and the single-wire serial communication circuit has a first signal transmitting terminal UART _ TXD1, a second signal transmitting terminal UART _ TXD2, a first signal receiving terminal UART _ RXD1, and a second signal receiving terminal UART _ RXD 2;
the signal end of the first communication circuit 1 is connected to the first signal receiving end UART _ RXD1, and the first signal receiving end UART _ RXD1 is connected to the signal end of the second communication circuit 2 through a single line LINK; the input end of the first communication circuit 1 is connected to the first signal transmitting end UART _ TXD 1;
the second communication circuit 2 includes a receiving circuit 21 for level-converting a signal from the first communication circuit 1 and a transmitting circuit 22 for level-converting a signal to be transmitted to the first communication circuit 1, wherein signal terminals of the second communication circuit 2 are respectively connected to an input terminal of the receiving circuit 21 and an output terminal of the transmitting circuit 22, an output terminal of the receiving circuit 21 is connected to the second signal receiving terminal UART _ RXD2, and an input terminal of the transmitting circuit 22 is connected to the second signal transmitting terminal UART _ TXD 2.
In some embodiments, referring to fig. 1, the first communication circuit 1 includes a first transistor Q1, a first resistor R1, a second resistor R2, and a third resistor R3;
an emitter of the first transistor Q1 is connected to the first signal transmitting terminal UART _ TXD 1; the base of the first triode Q1 is connected between the first resistor R1 and the third resistor R3, the first resistor R1 is connected with a first power supply, and the third resistor R3 is grounded; a collector of the first transistor Q1 is respectively connected to one end of the second resistor R2 and the first signal receiving terminal UART _ RXD1, and the other end of the second resistor R2 is connected to the first power supply.
It should be noted that the first resistor R1 is connected between the first power control signal and the base of the first transistor Q1, so as to prevent the transistor from being burned out by too large base current, and to perform the function of limiting current, for example, 1k is selected. The second resistor R2 is connected to the collector of the first transistor Q1, so that the changed current is converted into a converted voltage, and a high-low level is output to amplify the voltage, for example, 2.2k is selected. The third resistor R3 is connected between the base of the first triode Q1 and the ground potential, and is a pull-down resistor, so that effective grounding is realized, and false operation is prevented, for example, 10k is selected.
In some embodiments, referring to fig. 1, the transmitting circuit 22 includes a second transistor Q2, a fourth resistor R4, and a fifth resistor R5;
an emitter of the second transistor Q2 is connected to the second signal transmitting terminal UART _ TXD2, a base of the second transistor Q2 is connected to a second power supply through the fifth resistor R5, a collector of the second transistor Q2 is connected to the second power supply through the fourth resistor R4, and a collector of the second transistor Q2 is connected to an output terminal of the transmitting circuit 22.
It should be noted that the fourth resistor R4 is connected to the collector of the second transistor Q2, so as to convert the changing current into a converted voltage, output a high level and a low level, and amplify the voltage, for example, 2.2k is selected. The fifth resistor R5 is connected between the second power control signal and the base of the second transistor Q2 to prevent the transistor from being burned out by too large base current, and the function of limiting current is achieved, for example, 1k is selected. The first power voltage may be the same as or different from the second power voltage.
Specifically, the power supply voltage of the first communication circuit 1 is 3V, the power supply voltage of the second communication circuit 2 is 1.8V, and the working principle of the second communication circuit 2 transmitting signals to the first communication circuit 1 is as follows:
if the second signal transmitting terminal UART _ TXD2 is a low level signal, the second transistor Q2 is turned on, the single line transmission signal LINK is a low level signal, and the first signal receiving terminal UART _ RXD1 outputs a low level signal. If the second signal transmitting terminal UART _ TXD2 is a high level signal, the second transistor Q2 is turned off at this time, the single line is pulled up to the high level signal by default, so that the transmission signal LINK is a high level signal, and the first signal receiving terminal UART _ RXD1 outputs a high level signal.
More specifically, if the second signal transmitting terminal UART _ TXD2 is 1.8V, and at this time, the second triode Vbe is equal to 0 approximately, and the conduction condition is not satisfied, then the Q2 is turned off, and since the single line is pulled up to 3V by default, the transmission signal LINK is 3V, and the output of the first signal receiving terminal UART _ RXD1 is 3V, so that the UART _ TXD2 is 1.8V, and the voltage on the LINK is 3V, thereby achieving level conversion.
In some embodiments, referring to fig. 1, the receiving circuit 21 includes a third transistor Q3, a sixth resistor R6, and a seventh resistor R7;
an emitter of the third transistor Q3 is connected to an input terminal of the receiving circuit 21, a collector of the third transistor Q3 is connected to the second signal receiving terminal UART _ RXD2, a base of the third transistor Q3 is connected between the sixth resistor R6 and the seventh resistor R7, the sixth resistor R6 is grounded, and the seventh resistor R7 is connected to a third power supply.
It should be noted that the seventh resistor R7 is connected between the third power control signal and the base of the third transistor Q3, and is a current-limiting resistor driven by the transistor to prevent the transistor from being burned out due to an excessive base current. Because the resistance value of the resistor is too small, the power consumption of a system can be increased, the driving capability of the triode is weak due to too large resistance value of the resistor, the triode is generally adjusted after being valued according to experience, and 2.2k is generally selected. The sixth resistor R6 is connected between the base of the third transistor Q3 and the ground potential, and is a pull-down resistor, which is beneficial to the turn-off of the accelerating transistor, and is usually 10 k. The third power supply voltage is greater than 0.7V and less than or equal to the first power supply voltage.
In a preferred embodiment, the first transistor Q1, the second transistor Q2, and the third transistor Q3 are NPN transistors. The first transistor Q1, the second transistor Q2 and the third transistor Q3 select, for example, a baud rate of 3Mbps according to the communication rate, and then the transistor bandwidth is selected to be 100 times (an empirical value) of the transmission frequency, so that the limitation of the communication rate due to too slow rate of the transistor is prevented.
For example, in this embodiment, when 3Mbps is converted into a square wave by using an OOK modulation method to be 1.5MHz, it is required that:
(1) the bandwidth BW is more than or equal to 1.5M 100-150M, namely Ts-666.6 ns
(2) Rise time Fall time requires less than 1/10Ts 66.6ns (empirical values, both generally require rising and falling edges to be less than 1/10 switching cycles)
Then LMBT3904 triode with bandwidth 300MHz and Rise time 35nS Fall time 50nS is selected.
Specifically, the power supply voltage of the first communication circuit 1 is 3V, the power supply voltage of the second communication circuit 2 is 1.8V, and the working principle of the first communication circuit 1 transmitting signals to the second communication circuit 2 is as follows:
if the first signal transmitting terminal UART _ TXD1 is a low level signal, the first transistor Q1 is turned on, the first signal receiving terminal UART _ RXD1 is a low level signal, the single line transmission signal LINK is a low level signal, and the receiving circuit receives the signal, the third transistor Q3 is turned on, and the second signal receiving terminal UART _ RXD2 outputs a low level signal. If the first signal transmitting terminal UART _ TXD1 is a high level signal, the first triode Q1 is turned off at this time, the single line is pulled up to the high level signal by default, so that the transmission signal LINK is a high level signal, the receiving circuit receives the high level signal, the third triode Q3 is turned off, and at this time, the second signal receiving terminal UART _ RXD2 outputs a high level signal by default.
More specifically, if the first signal transmitting terminal UART _ TXD1 is 2.8V, the first triode Q1 is turned off, the single line is pulled up to 3V by default, so that the transmission signal LINK is 3V, the receiving circuit receives the signal, the third triode Q3 is turned off, the second signal receiving terminal UART _ RXD2 outputs 3V by default, the UART _ TXD1 is 2.8V, the UART _ RXD2 outputs 3V, and the single line normal communication from 3V to 1.8V is realized through level conversion.
The utility model discloses a single line serial port communication circuit, single line serial port communication circuit includes first communication circuit and second communication circuit, single line serial port communication circuit has first signal transmitting terminal, second signal transmitting terminal, first signal receiving terminal and second signal receiving terminal, the signal end of first communication circuit with first signal receiving terminal is connected, first signal receiving terminal through the single line with the signal end of second communication circuit is connected; the input end of the first communication circuit is connected with the first signal sending end, the second communication circuit comprises a receiving circuit used for carrying out level conversion on signals from the first communication circuit and a sending circuit used for carrying out level conversion on signals sent to the first communication circuit, the signal end of the second communication circuit is respectively connected with the input end of the receiving circuit and the output end of the sending circuit, the output end of the receiving circuit is connected with the second signal receiving end, and the input end of the sending circuit is connected with the second signal sending end. By arranging the transmitting circuit and the receiving circuit with the level conversion function, the first communication circuit is controlled to transmit signals to the second communication circuit under the condition that the power supply voltages of the two communication circuits are different, the second communication circuit is controlled to transmit signals to the first communication circuit, the transmission and the reception are realized, and the single-wire serial communication can be normally carried out. And simultaneously, the utility model discloses a circuit structure is simplified to the structure, has reduced the hardware cost to be applicable to multiple different supply voltage's the condition, have the wide characteristics of application scope.
In some embodiments, referring to fig. 1, the second communication circuit 2 further includes a clamping circuit 23;
the clamping circuit 23 is connected to the base of the second transistor Q2.
In this embodiment, when the rate is increased to a certain extent, due to the turn-off delay characteristic of the transistor, the voltage of the base of the second transistor Q2 will rise and exceed 1.8V, causing the transistor to operate in the variable resistance region, and causing the communication rate to be limited. Through setting up the clamp circuit, realize carrying out the chopper clamp to the base voltage of second triode Q2, can effectively promote communication rate.
In some embodiments, referring to fig. 1, the clamping circuit 23 includes a clamping diode D1;
the anode of the clamping diode D1 is connected with the base of the second triode Q2, and the cathode of the clamping diode D1 is connected with a fourth power supply.
In the embodiment, a clamping diode D1 is arranged for rapidly turning off the clamping of the second triode Q2, so that the communication baud rate is improved to 3 Mpbs. The utility model is suitable for an equipment of other different supply voltage, for example 5V changes 3.3V, 5V changes 1.8V etc, but circuit parameter needs adjust according to actual conditions, for example under 5V changes 3.3V circumstances, the clamp voltage VCC1V of clamp diode D1 need be changed into 2.5V, just can guarantee that clamp diode D1's anode voltage is close 3.3V, and wherein 0.8V is about the conduction-on voltage drop of diode.
In some embodiments, the clamp circuit 23 includes a voltage regulator tube and a current limiting resistor;
the positive electrode of the voltage regulator tube is grounded, the base electrode of the second triode Q2 is connected between the negative electrode of the voltage regulator tube and the first end of the current-limiting resistor, and the second end of the current-limiting resistor is connected with the second power supply.
In this embodiment, the clamp circuit 23 may be implemented by connecting a current-limiting resistor in series with a voltage regulator tube, the voltage of the voltage regulator tube needs to be close to the power supply voltage of the second triode Q2, and the current-limiting resistor is determined according to the voltage regulator tube option, so that the current flowing through the voltage regulator tube is 1-5 mA by generally selecting the current-limiting resistor.
The foregoing is 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 principle of the present invention, and these improvements and decorations are also considered as the protection scope of the present invention.
Claims (8)
1. A single-wire serial port communication circuit is characterized by comprising a first communication circuit and a second communication circuit, wherein the single-wire serial port communication circuit is provided with a first signal sending end, a second signal sending end, a first signal receiving end and a second signal receiving end;
the signal end of the first communication circuit is connected with the first signal receiving end, and the first signal receiving end is connected with the signal end of the second communication circuit through a single wire; the input end of the first communication circuit is connected with the first signal sending end;
the second communication circuit comprises a receiving circuit used for carrying out level conversion on signals from the first communication circuit and a sending circuit used for carrying out level conversion on signals sent to the first communication circuit, the signal end of the second communication circuit is respectively connected with the input end of the receiving circuit and the output end of the sending circuit, the output end of the receiving circuit is connected with the second signal receiving end, and the input end of the sending circuit is connected with the second signal sending end.
2. The single-wire serial port communication circuit according to claim 1, wherein the first communication circuit comprises a first triode, a first resistor, a second resistor and a third resistor;
the emitting electrode of the first triode is connected with the first signal sending end; the base electrode of the first triode is connected between the first resistor and the third resistor, the first resistor is connected with a first power supply, and the third resistor is grounded; and the collector of the first triode is respectively connected with one end of the second resistor and the first signal receiving end, and the other end of the second resistor is connected with the first power supply.
3. The single-wire serial port communication circuit according to claim 2, wherein the transmitting circuit comprises a second triode, a fourth resistor and a fifth resistor;
the emitting electrode of the second triode is connected with the second signal sending end, the base electrode of the second triode is connected with the second power supply through the fifth resistor, the collecting electrode of the second triode is connected with the second power supply through the fourth resistor, and the collecting electrode of the second triode is connected with the output end of the sending circuit.
4. The single-wire serial port communication circuit according to claim 3, wherein the receiving circuit comprises a third triode, a sixth resistor and a seventh resistor;
an emitting electrode of the third triode is connected with an input end of the receiving circuit, a collector electrode of the third triode is connected with the second signal receiving end, a base electrode of the third triode is connected between the sixth resistor and the seventh resistor, the sixth resistor is grounded, and the seventh resistor is connected with a third power supply.
5. The single-wire serial-port communication circuit of claim 4 wherein the second communication circuit further comprises a clamping circuit;
the clamping circuit is connected to the base electrode of the second triode.
6. The single-wire serial-port communication circuit according to claim 5, wherein the clamping circuit comprises a clamping diode;
the positive electrode of the clamping diode is connected with the base electrode of the second triode, and the negative electrode of the clamping diode is connected with a fourth power supply.
7. The single-wire serial port communication circuit according to claim 5, wherein the clamping circuit comprises a voltage regulator tube and a current limiting resistor;
the anode of the voltage regulator tube is grounded, the base electrode of the second triode is connected between the cathode of the voltage regulator tube and the first end of the current-limiting resistor, and the second end of the current-limiting resistor is connected with the second power supply.
8. The single-wire serial port communication circuit according to claim 4, wherein the first transistor, the second transistor and the third transistor are NPN transistors.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202120716663.9U CN214474985U (en) | 2021-04-08 | 2021-04-08 | Single-wire serial port communication circuit |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202120716663.9U CN214474985U (en) | 2021-04-08 | 2021-04-08 | Single-wire serial port communication circuit |
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| Publication Number | Publication Date |
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| CN214474985U true CN214474985U (en) | 2021-10-22 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN202120716663.9U Active CN214474985U (en) | 2021-04-08 | 2021-04-08 | Single-wire serial port communication circuit |
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