CN216053015U - Communication circuit of self-adaptation TTL or RS232 - Google Patents

Abstract

The utility model provides a self-adaptive TTL or RS232 communication circuit, and relates to the field of computer communication; the method comprises the following steps: the first communication terminal is used for inputting TTL signals or RS232 signals; the second communication end is used for outputting TTL signals; a first signal conversion module; a first path selection module; the collector of the NPN type triode is connected with one end of a first resistor and the anode of a diode, the other end of the first resistor is connected with a power supply end and one end of a second resistor, the base of the NPN type triode is connected with the other end of the second resistor and one end of a third resistor, the cathode of the diode is connected with one end of a capacitor, one end of a fourth resistor and the control end of the first path selection module, and the other end of the third resistor is connected with the first communication end. The utility model has the advantages that: the discrete element is adopted to build the signal detection module, so that the cost is low and the debugging is easy; when RS232 signal input is detected, the conversion is automatically carried out to TTL signal output, and when TTL signal input is detected, TTL signal output is kept, and self-adaptive communication is carried out.

Description

Communication circuit of self-adaptation TTL or RS232

Technical Field

The utility model relates to a computer communication technology, in particular to a communication circuit of self-adaptive TTL or RS 232.

Background

In some peripheral products in the market at present, interface communication is TTL signals or RS232 signals, and at the moment, a host and the peripheral can be selected and matched only by disassembling the machine, and adaptation can be carried out through selective welding of a 0 omega resistor or gating of a dial switch or by using some complex self-adaptive circuits.

The existing adaptive circuit has the following defects:

the technical scheme of the patent document has the defects that a master control MCU is required to judge a serial port communication mode, and the MCU is required to gate a serial port TTL or RS232, so that the workload of software is increased, and the compatibility of the circuit is reduced.

The application number 201610822905.6 is named as a self-adaptive TTL and RS232 serial port communication method, and the technical scheme of the patent document has the defects that a TTL or RS232 judgment and gating self-locking circuit is complex, a series of ICs are used, the cost is high, and the logic is complex.

The application number 201510361884.8 is named as a serial TTL/RS232 level self-adaptive device, and the technical scheme of the patent document has the defect that the external equipment is not required to be inserted again for self-adaptive communication again under the condition that the host is not powered off; that is, if the peripheral is TTL or RS232 communication, the host cannot communicate with the RS232 or TTL peripheral without power failure.

SUMMERY OF THE UTILITY MODEL

The utility model aims to solve the technical problem of providing a self-adaptive TTL or RS232 communication circuit, wherein a discrete element is adopted to build a signal detection module, when RS232 signal input is detected, the signal detection module is automatically converted into TTL signal output, and when TTL signal input is detected, the TTL signal output is kept.

The utility model is realized by the following steps: an adaptive TTL or RS232 communication circuit, comprising:

the first communication terminal is used for inputting TTL signals or RS232 signals;

the second communication end is used for outputting TTL signals;

the first signal conversion module is used for converting the TTL signal and the RS232 signal;

the first path selection module comprises a first signal end, a second signal end, a third signal end and a control end, wherein when the control end is at a low level, the first signal end is conducted with the third signal end, and when the control end is at a high level, the second signal end is conducted with the third signal end;

the first communication end is connected with the input end of the first signal conversion module and the first signal end of the first channel selection module, the output end of the first signal conversion module is connected with the second signal end of the first channel selection module, and the third signal end of the first channel selection module is connected with the second communication end;

the signal detection module comprises an NPN type triode, wherein a collector electrode of the NPN type triode is connected with one end of a first resistor and an anode of a diode, the other end of the first resistor is connected with a power supply end and one end of a second resistor, a base electrode of the NPN type triode is connected with the other end of the second resistor and one end of a third resistor, a cathode of the diode is connected with one end of a capacitor, one end of a fourth resistor and a control end of the first path selection module, an emitting electrode of the NPN type triode, the other end of the capacitor and the other end of the fourth resistor are all grounded, and the other end of the third resistor is connected with the first communication end.

Further, still include:

the third communication end is used for outputting TTL signals or RS232 signals;

the fourth communication end is used for inputting TTL signals;

the second signal conversion module has the same function as the first signal conversion module;

a second path selection module having the same function as the first path selection module;

the fourth communication end is connected with the input end of the second signal conversion module and the first signal end of the second channel selection module, the output end of the second signal conversion module is connected with the second signal end of the second channel selection module, the third signal end of the second channel selection module is connected with the third communication end, and the control end of the second channel selection module is connected with the control end of the first channel selection module.

Further, still include: and the TX end of the peripheral interface is connected with the first communication end, and the RX end of the peripheral interface is connected with the third communication end.

Further, the peripheral interface is connected with a fingerprint instrument module or a camera module or a sensor module.

Further, still include: and the RX end of the host interface is connected with the second communication end, and the TX end of the host interface is connected with the fourth communication end.

Furthermore, the host interface is connected with the MCU, the RX end of the host interface is connected with the cathode of the first voltage-regulator tube and one end of a fifth resistor, the other end of the fifth resistor is connected with the second communication end, the TX end of the host interface is connected with the cathode of the second voltage-regulator tube and one end of a sixth resistor, the other end of the sixth resistor is connected with the fourth communication end, and the anode of the first voltage-regulator tube and the anode of the second voltage-regulator tube are both grounded.

Further, the first signal conversion module and the second signal conversion module are combined into an integrated signal conversion module.

Further, the resistance value of the fourth resistor is far larger than that of the first resistor.

Further, the diode is a light emitting diode.

Further, the first communication terminal is used for outputting a TTL signal;

the second communication terminal is used for inputting TTL signals or RS232 signals;

the other end of the third resistor is connected with the second communication end.

The utility model has the advantages that: 1. the discrete element is adopted to build the signal detection module, so that the cost is low and the debugging is easy; when RS232 signal input is detected, the conversion is automatically carried out to TTL signal output, and when TTL signal input is detected, TTL signal output is kept, and self-adaptive communication is carried out. 2. And an MCU is not needed to intervene to detect TTL or RS232 signals, so that the workload of software is reduced, and the compatibility of the circuit is improved. 3. And the self-adaptive communication with the peripheral is carried out again under the condition that the host is not powered off. 4. When detecting that the peripheral interface is an RS232 signal, the TTL signal of the host interface can be converted into the RS232 signal to be sent to the peripheral interface. 5. Voltage-stabilizing tubes are arranged at the RX end and the TX end of the host interface, amplitude limiting is carried out on signal levels which may occur, and the MCU is protected.

Drawings

The utility model will be further described with reference to the following examples with reference to the accompanying drawings.

FIG. 1 is a schematic diagram of an adaptive TTL or RS232 communication circuit according to the present invention.

Fig. 2 is a schematic diagram of a signal detection module according to the present invention.

FIG. 3 is a first schematic diagram of the connection of the signal conversion module, the path selection module, the peripheral interface and the MCU in the present invention.

FIG. 4 is a second schematic diagram of the connection between the signal conversion module, the path selection module, the peripheral interface and the MCU.

Detailed Description

The embodiment of the utility model provides a self-adaptive TTL or RS232 communication circuit, overcomes the defects of three patent documents in the background technology, and achieves the technical effects of low cost, easy debugging, circuit compatibility improvement and support of communication with the peripheral equipment again when a host is not powered off.

In order to solve the above disadvantages, the technical solution in the embodiment of the present invention has the following general idea:

according to the communication mode of the RS232 signal: -3 to-15V are logic '1', and 3 to 15V are logic '0'; the communication mode of the TTL signals is as follows: 2-5V is logic '1', 0-0.8V is logic '0'; the initial states of the RS232 signal external equipment and the TTL signal external equipment are all '1' when being powered on, a discrete element is adopted to build a signal detection module, when the RS232 signal external equipment is detected, the signal detection module outputs a high level to a control end of a channel selection module, the RS232 signal is automatically converted into the TTL signal and transmitted to a host, when the TTL signal external equipment is detected, the signal detection module outputs a low level to the control end of the channel selection module, the TTL signal is kept and transmitted to the host, and self-adaptive communication is achieved.

For better understanding of the above technical solutions, the following detailed descriptions will be provided in conjunction with the drawings and the detailed description of the embodiments.

Referring to fig. 1 to 3, a first embodiment of the present invention is shown.

An adaptive TTL or RS232 communication circuit, comprising: the first communication terminal a1 is used for inputting TTL signals or RS232 signals; the second communication terminal a2 is used for outputting TTL signals; the first signal conversion module is used for converting the TTL signal and the RS232 signal; a first path selection module U1, including a first signal terminal S1, a second signal terminal S2, a third signal terminal S3 and a control terminal Det, wherein when the control terminal Det is at a low level, the first signal terminal S1 and the third signal terminal S3 are turned on, and when the control terminal Det is at a high level, the second signal terminal S2 and the third signal terminal S3 are turned on; the first communication terminal a1 is connected to the input terminal of the first signal conversion module and the first signal terminal S1 of the first path selection module U1, the output terminal of the first signal conversion module is connected to the second signal terminal S2 of the first path selection module U1, and the third signal terminal S3 of the first path selection module U1 is connected to the second communication terminal a 2; that is, when the control terminal Det of the first path selecting module U1 is at a low level, the signal of the first communication terminal a1 is directly transmitted to the second communication terminal a2, and when the control terminal Det of the first path selecting module U1 is at a high level, the signal of the first communication terminal a1 is converted by the first signal converting module and then transmitted to the second communication terminal a 2. The signal of the first communication terminal A1 comes from the peripheral, and the signal of the second communication terminal A2 is transmitted to the host.

The signal detection module U4 includes an NPN transistor Q1 having a collector connected to one end of a first resistor R1 and an anode of a diode D1, the other end of the first resistor R1 being connected to a power supply terminal and one end of a second resistor R2, a base of the NPN transistor Q1 being connected to the other end of the second resistor R2 and one end of a third resistor R3, a cathode of the diode D1 being connected to one end of a capacitor C1, one end of a fourth resistor R4 and a control terminal Det of the first path selection module U1, an emitter of the NPN transistor Q1, the other end of the capacitor C1 and the other end of the fourth resistor R4 being grounded, and the other end of the third resistor R3 being connected to the first communication terminal a 1. The power supply terminal is 5.0V and the capacitor C1 is not yet charged. According to the communication mode of the RS232 signal: -3 to-15V are logic '1', and 3 to 15V are logic '0'; the communication mode of the TTL signals is as follows: 2-5V is logic '1', 0-0.8V is logic '0'; the initial states of the RS232 signal external device and the TTL signal external device at power-on are both "1". If the peripheral equipment is used for TTL signal communication, the external equipment firstly sends logic '1', namely 2-5V, of the TTL signal to a first communication end A1, and loads the logic '1' to the base electrode of an NPN type triode Q1 through a third resistor R3, at the moment, the base electrode level of the NPN type triode Q1 is larger than the threshold value of the conduction of the NPN type triode Q1, so that an NPN type triode Q1 is conducted, the collector electrode of an NPN type triode Q1 is changed into low level, a diode D1 is cut off, a control end Det of a first channel selection module U1 is in low level, the signal of a first communication end A1 is directly transmitted to a second communication end A2, and the peripheral equipment and a host machine are in TTL signal communication; in the communication process, the TTL signal is a square wave, the peripheral sends logic "0", that is, 0-0.8V, of the TTL signal to the first communication terminal a1, because the power supply terminal 5.0V acts on the base of the NPN transistor Q1 through the second resistor R2, the base of the NPN transistor Q1 is still at a high level at this time, which is greater than the threshold value of the NPN transistor Q1, the NPN transistor Q1 remains on, the collector of the NPN transistor Q1 remains at a low level, the diode D1 remains off, the control terminal Det of the first path selection module U1 remains at a low level, and the peripheral and the host keep TTL signal communication. If the peripheral equipment is used for RS232 signal communication, the external equipment firstly sends logic '1', namely-3 to-15V, of an RS232 signal to a first communication end A1, at the moment, the base electrode level of an NPN type triode Q1 is lower than the conduction threshold value of an NPN type triode Q1, the NPN type triode Q1 is in a cut-off state, the collector electrode of the NPN type triode Q1 is at a high level, a diode D1 is conducted, a capacitor C1 is rapidly charged, the charging time of the capacitor C1 is 0.1 second, and therefore the high level is output to a control end Det of a first channel selection module U1, the RS232 signal of the first communication end A1 is converted into a TTL signal through a first signal conversion module and then transmitted to a second communication end A2, and the peripheral equipment and a host machine carry out RS232 signal to TTL signal communication; in the communication process, the RS232 signal is a square wave, the peripheral sends logic '0' of the RS232 signal, that is, 3-15V, to the first communication terminal a1, at this time, the base level of the NPN transistor Q1 becomes higher than the threshold value of the NPN transistor Q1, the NPN transistor Q1 becomes a conducting state, the collector of the NPN transistor Q1 becomes a low level, the diode D1 becomes a cut-off state, at this time, the capacitor C1 can only discharge through the fourth resistor R4, so that the high level is continuously output to the control terminal Det of the first path selection module U1; the resistance value of the fourth resistor R4 is much greater than that of the first resistor R1, so that the discharging time of the capacitor C1 is much greater than the charging time, and thus before the capacitor C1 discharges to change the control terminal Det of the first channel selection module U1 to a low level, the peripheral device further sends logic "1" of the RS232 signal, i.e., -3 to-15V, to the first communication terminal a1, at this time, the NPN type triode Q1 becomes an off state, the diode D1 becomes an on state, the power terminal 5.0V charges the capacitor C1 through the first resistor R1 and the diode D1, so that the control terminal Det of the first channel selection module U1 is maintained at a high level, and the peripheral device maintains the RS232 signal to the TTL signal communication with the host.

When the signal detection module U4 detects the input of the RS232 signal of the peripheral equipment, the utility model automatically converts the signal into a TTL signal and outputs the TTL signal to the host, and when the input of the TTL signal of the peripheral equipment is detected, the utility model keeps the TTL signal output to the host and realizes the self-adaptive communication.

When the first communication terminal a1 is disconnected from the peripheral device, the first communication terminal a1 is suspended, the power supply terminal 5.0V acts on the base of the NPN-type triode Q1 through the second resistor R2, so that the NPN-type triode Q1 is turned on, the collector of the NPN-type triode Q1 is at a low level, the diode D1 is turned off, the capacitor C1 can only discharge through the fourth resistor R4, and when the capacitor C1 discharges to a low level, the initial state judgment is provided for the next peripheral device insertion. Therefore, the utility model supports that the peripheral equipment can be inserted again to carry out self-adaptive communication with the peripheral equipment again under the condition that the host machine does not need to be powered off.

The third communication terminal a3 is used for outputting a TTL signal or an RS232 signal; a fourth communication terminal a4 for inputting TTL signals; the second signal conversion module has the same function as the first signal conversion module; the first signal conversion module and the second signal conversion module are combined into a whole signal conversion module U3; the overall signal conversion module U3 is of type MAX 232. A second path selection module U2 having the same function as the first path selection module U1; the first path selection module U1 and the second path selection module U2 are both TMUX 7219.

The fourth communication terminal a4 is connected to the input terminal of the second signal conversion module and the first signal terminal S1 of the second channel selection module U2, the output terminal of the second signal conversion module is connected to the second signal terminal S2 of the second channel selection module U2, the third signal terminal S3 of the second channel selection module U2 is connected to the third communication terminal A3, and the control terminal Det of the second channel selection module U2 is connected to the control terminal Det of the first channel selection module U1. That is, when the control terminal Det of the second path selecting module U2 is at a low level, the signal of the fourth communication terminal a4 is directly transmitted to the third communication terminal A3, and when the control terminal Det of the second path selecting module U2 is at a high level, the signal of the fourth communication terminal a4 is converted by the second signal converting module and then transmitted to the third communication terminal A3. The signal of the fourth communication terminal a4 comes from the host, and the third communication terminal A3 transmits the signal to the peripheral.

When the signal detection module U4 detects that the peripheral device adopts RS232 signal communication, the utility model automatically converts TTL signals of the host into RS232 signals and outputs the RS232 signals to the peripheral device, and when the peripheral device detects that the peripheral device adopts TTL signal communication, the utility model keeps the host and the peripheral device to carry out TTL signal communication.

A TX end of the peripheral interface J1 is connected to the first communication end a1, and an RX end of the peripheral interface J1 is connected to the third communication end A3. The peripheral interface J1 is connected with a fingerprint instrument module or a camera module or a sensor module.

An RX end of the host interface J2 is connected to the second communication end a2, and a TX end of the host interface J2 is connected to the fourth communication end a 4. The host interface J2 is connected with the MCU, the RX end of the host interface J2 is connected with the cathode of a first voltage-regulator tube D2 and one end of a fifth resistor R5, the other end of the fifth resistor R5 is connected with the second communication end A2, the TX end of the host interface J2 is connected with the cathode of a second voltage-regulator tube D3 and one end of a sixth resistor R6, the other end of the sixth resistor R6 is connected with the fourth communication end A4, and the anode of the first voltage-regulator tube D2 and the anode of the second voltage-regulator tube D3 are both grounded; and a voltage stabilizing tube is arranged to limit the amplitude of the signal level which may appear, and is limited to-0.6V-5.6V, so that the MCU is protected. Because the initial state of the capacitor C1 is low level, when the connected peripheral equipment adopts RS232 signal communication, the capacitor C1 can be charged for 0.1 second, the capacitor C1 is at the low level of 0.1 second, in the time, the logic '1' of the RS232 signal, namely-3 to-15V, can be directly transmitted to the second communication end A2 from the first communication end A1, and the voltage regulator tube carries out amplitude limiting on-3 to-15V, thereby protecting the MCU.

The diode D1 is a light emitting diode D1. When the RS232 signal is input to the first communication terminal a1, since the RS232 signal is a square wave, the led D1 periodically switches between the on state and the off state, and thus the led D1 flickers to indicate that the RS232 signal is used for communication.

The working mode of the self-adaptive TTL or RS232 communication circuit of the utility model is as follows: the external interface J1 is inserted into the external device, if the external device is detected to adopt TTL signal communication, the TTL signal of the external device is directly transmitted to the host, and the TTL signal of the host is directly transmitted to the external device; when detecting that the external equipment adopts RS232 signal communication, converting the RS232 signal of the external equipment into a TTL signal and transmitting the TTL signal to the host, and converting the TTL signal of the host into an RS232 signal and transmitting the RS232 signal to the external equipment; the external equipment can be plugged again or replaced without powering off the host; the signal detection module U4 adopts discrete components, has low cost and easy debugging, does not need an MCU to intervene to detect TTL signals or RS232 signals, reduces the software workload in the MCU, simultaneously, the MCU does not participate in the control of channel selection, and improves the compatibility and the adaptability of the circuit.

Referring to fig. 4, a second embodiment of the present invention is shown.

The first communication terminal a1 is used for outputting TTL signals; the second communication terminal a2 is used for inputting TTL signals or RS232 signals; the other end of the third resistor R3 is connected to the second communication terminal A2. The signal of the second communication terminal A2 comes from the peripheral, and the first communication terminal A1 transmits the signal to the host. In the second embodiment of the present invention, if the peripheral device uses RS232 signal communication, the RS232 signal enters the second communication terminal a2, and is converted into a TTL signal through the first path selection module U1 and the first signal conversion module, and then is transmitted to the first communication terminal a 1.

In the second embodiment of the present invention, the third communication terminal a3 is used for inputting TTL signals; the fourth communication terminal a4 is used for outputting TTL signals or RS232 signals; the signal of the third communication terminal A3 comes from the host, and the fourth communication terminal a4 transmits the signal to the peripheral. If the peripheral device adopts RS232 signal communication, the TTL signal of the host enters the third communication terminal A3, and is converted into an RS232 signal through the second channel selection module U2 and the second signal conversion module, and then the RS232 signal is transmitted to the fourth communication terminal A4.

In the first embodiment of the present invention, if the peripheral device uses RS232 signal communication, the RS232 signal enters the first communication terminal a1, and is converted into a TTL signal through the first signal conversion module and the first path selection module U1, and then the TTL signal is transmitted to the second communication terminal a 2; the TTL signal of the host enters the fourth communication terminal a4, is converted into an RS232 signal by the second signal conversion module and the second path selection module U2, and is transmitted to the third communication terminal A3.

A TX end of the peripheral interface J1 is connected to the second communication end a2, and an RX end of the peripheral interface J1 is connected to the fourth communication end a 4.

An RX end of the host interface J2 is connected to the first communication end a1, and a TX end of the host interface J2 is connected to the third communication end A3.

The second embodiment of the present invention provides another circuit connection method on the basis of unchanged technical concept, and other parts not described above refer to the first embodiment of the present invention.

Although specific embodiments of the utility model have been described above, it will be understood by those skilled in the art that the specific embodiments described are illustrative only and are not limiting upon the scope of the utility model, and that equivalent modifications and variations can be made by those skilled in the art without departing from the spirit of the utility model, which is to be limited only by the appended claims.

Claims (10)

1. An adaptive TTL or RS232 communication circuit, comprising:

the first communication terminal is used for inputting TTL signals or RS232 signals;

the second communication end is used for outputting TTL signals;

the first signal conversion module is used for converting the TTL signal and the RS232 signal;

the first path selection module comprises a first signal end, a second signal end, a third signal end and a control end, wherein when the control end is at a low level, the first signal end is conducted with the third signal end, and when the control end is at a high level, the second signal end is conducted with the third signal end;

the first communication end is connected with the input end of the first signal conversion module and the first signal end of the first channel selection module, the output end of the first signal conversion module is connected with the second signal end of the first channel selection module, and the third signal end of the first channel selection module is connected with the second communication end;

the signal detection module comprises an NPN type triode, wherein a collector electrode of the NPN type triode is connected with one end of a first resistor and an anode of a diode, the other end of the first resistor is connected with a power supply end and one end of a second resistor, a base electrode of the NPN type triode is connected with the other end of the second resistor and one end of a third resistor, a cathode of the diode is connected with one end of a capacitor, one end of a fourth resistor and a control end of the first path selection module, an emitting electrode of the NPN type triode, the other end of the capacitor and the other end of the fourth resistor are all grounded, and the other end of the third resistor is connected with the first communication end.

2. The adaptive TTL or RS232 communication circuit as recited in claim 1, further comprising:

the third communication end is used for outputting TTL signals or RS232 signals;

the fourth communication end is used for inputting TTL signals;

the second signal conversion module has the same function as the first signal conversion module;

a second path selection module having the same function as the first path selection module;

the fourth communication end is connected with the input end of the second signal conversion module and the first signal end of the second channel selection module, the output end of the second signal conversion module is connected with the second signal end of the second channel selection module, the third signal end of the second channel selection module is connected with the third communication end, and the control end of the second channel selection module is connected with the control end of the first channel selection module.

3. The adaptive TTL or RS232 communication circuit as recited in claim 2, further comprising: and the TX end of the peripheral interface is connected with the first communication end, and the RX end of the peripheral interface is connected with the third communication end.

4. The adaptive TTL or RS232 communication circuit of claim 3 wherein: the peripheral interface is connected with the fingerprint instrument module or the camera module or the sensor module.

5. The adaptive TTL or RS232 communication circuit as recited in claim 2, further comprising: and the RX end of the host interface is connected with the second communication end, and the TX end of the host interface is connected with the fourth communication end.

6. The adaptive TTL or RS232 communication circuit of claim 5 wherein: the host interface is connected with the MCU, the RX end of the host interface is connected with the cathode of the first voltage-stabilizing tube and one end of a fifth resistor, the other end of the fifth resistor is connected with the second communication end, the TX end of the host interface is connected with the cathode of the second voltage-stabilizing tube and one end of a sixth resistor, the other end of the sixth resistor is connected with the fourth communication end, and the anode of the first voltage-stabilizing tube and the anode of the second voltage-stabilizing tube are both grounded.

7. The adaptive TTL or RS232 communication circuit as recited in claim 2, wherein: the first signal conversion module and the second signal conversion module are combined into an integral signal conversion module.

8. The adaptive TTL or RS232 communication circuit of claim 1, wherein: the resistance value of the fourth resistor is far larger than that of the first resistor.

9. The adaptive TTL or RS232 communication circuit of claim 1, wherein: the diode is a light emitting diode.

10. The adaptive TTL or RS232 communication circuit of claim 1, wherein:

the first communication terminal is used for outputting TTL signals;

the second communication terminal is used for inputting TTL signals or RS232 signals;

the other end of the third resistor is connected with the second communication end.

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